Spectral domain optical coherence tomography imaging of retinal diseases in Singapore.

PubMed

Singh, Mandeep; Chee, Caroline K L

2009-01-01

In this retrospective case series, the authors reviewed cases of patients with macular disorders whose eyes had been imaged using spectral domain optical coherence tomography (SD-OCT) (Cirrus HD-OCT; Carl Zeiss Meditec, Inc., Dublin, CA). SD-OCT images were obtained from patients with a variety of ocular conditions attending a tertiary retinal clinic in Singapore from August 2007 to December 2007, according to standardized protocols. Images of 428 eyes from 301 patients were reviewed. Ocular diagnoses included diabetic macular edema, exudative age-related macular degeneration, central serous chorioretinopathy, cystoid macular edema, retinal vein and artery occlusions, infective chorioretinitis, and others. The authors present four cases of particular interest to illustrate how SD-OCT was useful in complementing the clinician's assessment of macular disease.

Retinal vessel oxygen saturation in a healthy young Chinese population.

PubMed

Yang, Wei; Fu, Yue; Dong, Yanmin; Lin, Leilei; Huang, Xia; Li, Yujie; Lin, Xiaofeng; Gao, Qianying

2016-06-01

To measure retinal vessel oxygen saturation in a healthy young Chinese population and to determine the effects of multiple factors (gender, age, dioptre, vessel diameter and ocular perfusion pressure - OPP) on retinal oxygen saturation. A total of 126 healthy Chinese individuals aged from 19 to 30 were included in this study. A retinal oximeter (Oxymap T1) was used to measure retinal vessel oxygen saturation by retinal imaging at two different wavelengths. The mean retinal vessel oxygen saturation (Sat_O2 ) of arterioles, venules and arteriovenous (AV) difference overall and in four separate quadrants were measured. Intra-ocular pressure, blood pressure, finger pulse oximetry value, vessel diameter and dioptre were also measured. The correlations between OPP and dioptre, OPP and vessel diameter, and dioptre and vessel diameter were analysed. And the effects of multiple factors on the retinal oxygen saturation were analysed. The mean oxygen saturation was 93.2 ± 6.3% in the retinal arterioles, 60.4 ± 5.3% in venules and 32.9 ± 6.4% in AV difference. The temporal quadrants had lower measurements of arteriolar and venular oxygen saturation and AV difference compared with nasal quadrants (p < 0.001). The oxygen saturation of the arterioles, venules and AV difference were unaffected by any unique factor. Arteriolar and venular retinal oxygen saturation correlated negatively with the product of dioptre and OPP. Arteriolar retinal oxygen saturation correlated positively with the product of dioptre and vessel diameter. This study provided a normal reference of Sat_O2 in healthy young Chinese individuals. It was a reflection of the normal state of retinal oxygen metabolism affected by several factors. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Neonatal systemic inflammation in rats alters retinal vessel development and simulates pathologic features of retinopathy of prematurity.

PubMed

Hong, Hye Kyoung; Lee, Hyun Ju; Ko, Jung Hwa; Park, Ji Hyun; Park, Ji Yeon; Choi, Chang Won; Yoon, Chang-Hwan; Ahn, Seong Joon; Park, Kyu Hyung; Woo, Se Joon; Oh, Joo Youn

2014-05-15

Alteration of retinal angiogenesis during development leads to retinopathy of prematurity (ROP) in preterm infants, which is a leading cause of visual impairment in children. A number of clinical studies have reported higher rates of ROP in infants who had perinatal infections or inflammation, suggesting that exposure of the developing retina to inflammation may disturb retinal vessel development. Thus, we investigated the effects of systemic inflammation on retinal vessel development and retinal inflammation in neonatal rats. To induce systemic inflammation, we intraperitoneally injected 100 μl lipopolysaccharide (LPS, 0.25 mg/ml) or the same volume of normal saline in rat pups on postnatal days 1, 3, and 5. The retinas were extracted on postnatal days 7 and 14, and subjected to assays for retinal vessels, inflammatory cells and molecules, and apoptosis. We found that intraperitoneal injection of LPS impaired retinal vessel development by decreasing vessel extension, reducing capillary density, and inducing localized overgrowth of abnormal retinal vessels and dilated peripheral vascular ridge, all of which are characteristic findings of ROP. Also, a large number of CD11c+ inflammatory cells and astrocytes were localized in the lesion of abnormal vessels. Further analysis revealed that the number of major histocompatibility complex (MHC) class IIloCD68loCD11bloCD11chi cells in the retina was higher in LPS-treated rats compared to controls. Similarly, the levels of TNF-α, IL-1β, and IL-12a were increased in LPS-treated retina. Also, apoptosis was increased in the inner retinal layer where retinal vessels are located. Our data demonstrate that systemic LPS-induced inflammation elicits retinal inflammation and impairs retinal angiogenesis in neonatal rats, implicating perinatal inflammation in the pathogenesis of ROP.

Automated method for identification and artery-venous classification of vessel trees in retinal vessel networks.

PubMed

Joshi, Vinayak S; Reinhardt, Joseph M; Garvin, Mona K; Abramoff, Michael D

2014-01-01

The separation of the retinal vessel network into distinct arterial and venous vessel trees is of high interest. We propose an automated method for identification and separation of retinal vessel trees in a retinal color image by converting a vessel segmentation image into a vessel segment map and identifying the individual vessel trees by graph search. Orientation, width, and intensity of each vessel segment are utilized to find the optimal graph of vessel segments. The separated vessel trees are labeled as primary vessel or branches. We utilize the separated vessel trees for arterial-venous (AV) classification, based on the color properties of the vessels in each tree graph. We applied our approach to a dataset of 50 fundus images from 50 subjects. The proposed method resulted in an accuracy of 91.44% correctly classified vessel pixels as either artery or vein. The accuracy of correctly classified major vessel segments was 96.42%.

Validation of Smartphone Based Retinal Photography for Diabetic Retinopathy Screening

PubMed Central

Rajalakshmi, Ramachandran; Arulmalar, Subramanian; Usha, Manoharan; Prathiba, Vijayaraghavan; Kareemuddin, Khaji Syed; Anjana, Ranjit Mohan; Mohan, Viswanathan

2015-01-01

Aim To evaluate the sensitivity and specificity of “fundus on phone’ (FOP) camera, a smartphone based retinal imaging system, as a screening tool for diabetic retinopathy (DR) detection and DR severity in comparison with 7-standard field digital retinal photography. Design Single-site, prospective, comparative, instrument validation study. Methods 301 patients (602 eyes) with type 2 diabetes underwent standard seven-field digital fundus photography with both Carl Zeiss fundus camera and indigenous FOP at a tertiary care diabetes centre in South India. Grading of DR was performed by two independent retina specialists using modified Early Treatment of Diabetic Retinopathy Study grading system. Sight threatening DR (STDR) was defined by the presence of proliferative DR(PDR) or diabetic macular edema. The sensitivity, specificity and image quality were assessed. Results The mean age of the participants was 53.5 ±9.6 years and mean duration of diabetes 12.5±7.3 years. The Zeiss camera showed that 43.9% had non-proliferative DR(NPDR) and 15.3% had PDR while the FOP camera showed that 40.2% had NPDR and 15.3% had PDR. The sensitivity and specificity for detecting any DR by FOP was 92.7% (95%CI 87.8–96.1) and 98.4% (95%CI 94.3–99.8) respectively and the kappa (ĸ) agreement was 0.90 (95%CI-0.85–0.95 p<0.001) while for STDR, the sensitivity was 87.9% (95%CI 83.2–92.9), specificity 94.9% (95%CI 89.7–98.2) and ĸ agreement was 0.80 (95%CI 0.71–0.89 p<0.001), compared to conventional photography. Conclusion Retinal photography using FOP camera is effective for screening and diagnosis of DR and STDR with high sensitivity and specificity and has substantial agreement with conventional retinal photography. PMID:26401839

3-D segmentation of retinal blood vessels in spectral-domain OCT volumes of the optic nerve head

NASA Astrophysics Data System (ADS)

Lee, Kyungmoo; Abràmoff, Michael D.; Niemeijer, Meindert; Garvin, Mona K.; Sonka, Milan

2010-03-01

Segmentation of retinal blood vessels can provide important information for detecting and tracking retinal vascular diseases including diabetic retinopathy, arterial hypertension, arteriosclerosis and retinopathy of prematurity (ROP). Many studies on 2-D segmentation of retinal blood vessels from a variety of medical images have been performed. However, 3-D segmentation of retinal blood vessels from spectral-domain optical coherence tomography (OCT) volumes, which is capable of providing geometrically accurate vessel models, to the best of our knowledge, has not been previously studied. The purpose of this study is to develop and evaluate a method that can automatically detect 3-D retinal blood vessels from spectral-domain OCT scans centered on the optic nerve head (ONH). The proposed method utilized a fast multiscale 3-D graph search to segment retinal surfaces as well as a triangular mesh-based 3-D graph search to detect retinal blood vessels. An experiment on 30 ONH-centered OCT scans (15 right eye scans and 15 left eye scans) from 15 subjects was performed, and the mean unsigned error in 3-D of the computer segmentations compared with the independent standard obtained from a retinal specialist was 3.4 +/- 2.5 voxels (0.10 +/- 0.07 mm).

Vessel extraction in retinal images using automatic thresholding and Gabor Wavelet.

PubMed

Ali, Aziah; Hussain, Aini; Wan Zaki, Wan Mimi Diyana

2017-07-01

Retinal image analysis has been widely used for early detection and diagnosis of multiple systemic diseases. Accurate vessel extraction in retinal image is a crucial step towards a fully automated diagnosis system. This work affords an efficient unsupervised method for extracting blood vessels from retinal images by combining existing Gabor Wavelet (GW) method with automatic thresholding. Green channel image is extracted from color retinal image and used to produce Gabor feature image using GW. Both green channel image and Gabor feature image undergo vessel-enhancement step in order to highlight blood vessels. Next, the two vessel-enhanced images are transformed to binary images using automatic thresholding before combined to produce the final vessel output. Combining the images results in significant improvement of blood vessel extraction performance compared to using individual image. Effectiveness of the proposed method was proven via comparative analysis with existing methods validated using publicly available database, DRIVE.

Assessing oxygen saturation in retinal vessels in high myopia patients pre- and post-implantable collamer lens implantation surgery.

PubMed

Chen, Pei; Cai, Xiaoxiao; Xu, Lijun; Zhang, Jing; Yang, Ying; Gao, Qianying; Ge, Jian; Yu, Keming; Zhuang, Jing

2017-09-01

To determine whether posterior chamber phakic implantable collamer lens (ICL) surgery in high myopia patients impedes oxygen saturation of retinal vessels. Mean oxygen saturation and diameter in retinal blood vessels were measured before and after ICL implantation surgery to correct high myopia refractive errors (i.e. -6.00 to -20.25 dioptres [D]), using an Oxymap T1 retinal oximeter. In 17 eyes of 17 patients, the Oxymap T1 retinal oximeter detected a small but significant decrease in oxygen saturation of retinal venules, 1-week postoperatively (compared to preoperative measurements). Moreover, at 1 week after ICL implantation, the diameter of patient retinal vessels had consistently contracted, compared to preoperative measurements. By 1 month after ICL surgery, however, both the oxygen saturation and retinal vessel diameter had returned to preoperative levels. Otherwise, no statistically significant difference in oxygen saturation and diameter of retinal arterioles was found when comparing their measurements before and 1 week after implantation. Stable levels of oxygen saturation in retinal vessels, as detected by the Oxymap T1 oximeter, show ICL implantation would not leave lasting impact or adverse effects to retina oxygen saturation in high myopia patients. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Technique of retinal gene therapy: delivery of viral vector into the subretinal space

PubMed Central

Xue, K; Groppe, M; Salvetti, A P; MacLaren, R E

2017-01-01

Purpose Safe and reproducible delivery of gene therapy vector into the subretinal space is essential for successful targeting of the retinal pigment epithelium (RPE) and photoreceptors. The success of surgery is critical for the clinical efficacy of retinal gene therapy. Iatrogenic detachment of the degenerate (often adherent) retina in patients with hereditary retinal degenerations and small volume (eg, 0.1 ml) subretinal injections pose new surgical challenges. Methods Our subretinal gene therapy technique involved pre-operative planning with optical coherence tomography (OCT) and autofluorescence (AF) imaging, 23 G pars plana vitrectomy, internal limiting membrane staining with Membrane Blue Dual (DORC BV, Zuidland, Netherlands), a two-step subretinal injection using a 41 G Teflon tipped cannula (DORC) first with normal saline to create a parafoveal bleb followed by slow infusion of viral vector via the same self-sealing retinotomy. Surgical precision was further enhanced by intraoperative OCT (Zeiss Rescan 7000, Carl Zeiss Meditec AG, Jena, Germany). Foveal functional and structural recovery was evaluated using best-corrected Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity, microperimetry and OCT. Results Two patients with choroideremia aged 29 (P1) and 27 (P2) years, who had normal and symmetrical levels of best-corrected visual acuity (BCVA) in both eyes, underwent unilateral gene therapy with the fellow eye acting as internal control. The surgeries were uncomplicated in both cases with successful detachment of the macula by subretinal vector injection. Both treated eyes showed recovery of BCVA (P1: 76–77 letters; P2: 84–88 letters) and mean threshold sensitivity of the central macula (P1: 10.7–10.7 dB; P2: 14.2–14.1 dB) to baseline within a month. This was accompanied by normalisation of central retinal thickness on OCT. Conclusions Herein we describe a reliable technique for subretinal gene therapy, which is currently used in clinical trials to treat choroideremia using an adeno-associated viral (AAV) vector encoding the CHM gene. Strategies to minimise potential complications, such as avoidance of excessive retinal stretch, air bubbles within the injection system, reflux of viral vector and post-operative vitritis are discussed. PMID:28820183

Application of morphological bit planes in retinal blood vessel extraction.

PubMed

Fraz, M M; Basit, A; Barman, S A

2013-04-01

The appearance of the retinal blood vessels is an important diagnostic indicator of various clinical disorders of the eye and the body. Retinal blood vessels have been shown to provide evidence in terms of change in diameter, branching angles, or tortuosity, as a result of ophthalmic disease. This paper reports the development for an automated method for segmentation of blood vessels in retinal images. A unique combination of methods for retinal blood vessel skeleton detection and multidirectional morphological bit plane slicing is presented to extract the blood vessels from the color retinal images. The skeleton of main vessels is extracted by the application of directional differential operators and then evaluation of combination of derivative signs and average derivative values. Mathematical morphology has been materialized as a proficient technique for quantifying the retinal vasculature in ocular fundus images. A multidirectional top-hat operator with rotating structuring elements is used to emphasize the vessels in a particular direction, and information is extracted using bit plane slicing. An iterative region growing method is applied to integrate the main skeleton and the images resulting from bit plane slicing of vessel direction-dependent morphological filters. The approach is tested on two publicly available databases DRIVE and STARE. Average accuracy achieved by the proposed method is 0.9423 for both the databases with significant values of sensitivity and specificity also; the algorithm outperforms the second human observer in terms of precision of segmented vessel tree.

The effect of autoimmune retinopathy on retinal vessel oxygen saturation.

PubMed

Waizel, Maria; Türksever, Cengiz; Todorova, Margarita G

2018-05-22

To study the retinal vessel oxygen saturation alterations in patients with autoimmune retinopathy (AIR) and patients with autoimmune retinopathy associated with retinitis pigmentosa (AIR-RP) in comparison with healthy controls and patients with isolated retinitis pigmentosa (RP). Prospective, cross-sectional, and non-interventional study. Retinal vessel oximetry (RO) was performed on a total of 139 eyes: six eyes suffering from AIR and four eyes with AIR-RP were compared to 59 healthy control eyes and to 70 eyes with RP. A computer-based program of the retinal vessel analyser unit (IMEDOS Systems UG, Jena, Germany) was used to evaluate retinal vessel oxygen saturation. The mean oxygen saturation in the first and second branch retinal arterioles (A-SO 2 ) and venules (V-SO 2 ) were measured and their difference (A-V SO 2 ) was calculated. In addition, we measured the diameter of the retinal arterioles (D-A) and venules (D-V). Oxygen metabolism is altered in patients with isolated AIR and AIR-RP. Both, AIR and AIR-RP groups, differed from healthy controls showing significantly higher V-SO 2 values and significantly lower A-V SO 2 values (p < 0.025). In addition, the AIR-RP group could be differentiated from eyes suffering from isolated RP by means of significantly higher V-SO 2 values. Comparing retinal vessel diameters, both, the AIR and AIR-RP groups, presented with significant arterial (p = 0.05) and venular (p < 0.03) vessel attenuation than the healthy control group. Based on our results, in analogy to patients suffering from RP, oxygen metabolism seems to be altered in AIR patients.

Retinal biometrics based on Iterative Closest Point algorithm.

PubMed

Hatanaka, Yuji; Tajima, Mikiya; Kawasaki, Ryo; Saito, Koko; Ogohara, Kazunori; Muramatsu, Chisako; Sunayama, Wataru; Fujita, Hiroshi

2017-07-01

The pattern of blood vessels in the eye is unique to each person because it rarely changes over time. Therefore, it is well known that retinal blood vessels are useful for biometrics. This paper describes a biometrics method using the Jaccard similarity coefficient (JSC) based on blood vessel regions in retinal image pairs. The retinal image pairs were rough matched by the center of their optic discs. Moreover, the image pairs were aligned using the Iterative Closest Point algorithm based on detailed blood vessel skeletons. For registration, perspective transform was applied to the retinal images. Finally, the pairs were classified as either correct or incorrect using the JSC of the blood vessel region in the image pairs. The proposed method was applied to temporal retinal images, which were obtained in 2009 (695 images) and 2013 (87 images). The 87 images acquired in 2013 were all from persons already examined in 2009. The accuracy of the proposed method reached 100%.

Probabilistic retinal vessel segmentation

NASA Astrophysics Data System (ADS)

Wu, Chang-Hua; Agam, Gady

2007-03-01

Optic fundus assessment is widely used for diagnosing vascular and non-vascular pathology. Inspection of the retinal vasculature may reveal hypertension, diabetes, arteriosclerosis, cardiovascular disease and stroke. Due to various imaging conditions retinal images may be degraded. Consequently, the enhancement of such images and vessels in them is an important task with direct clinical applications. We propose a novel technique for vessel enhancement in retinal images that is capable of enhancing vessel junctions in addition to linear vessel segments. This is an extension of vessel filters we have previously developed for vessel enhancement in thoracic CT scans. The proposed approach is based on probabilistic models which can discern vessels and junctions. Evaluation shows the proposed filter is better than several known techniques and is comparable to the state of the art when evaluated on a standard dataset. A ridge-based vessel tracking process is applied on the enhanced image to demonstrate the effectiveness of the enhancement filter.

NOVEL PRERETINAL HAIR PIN-LIKE VESSEL IN RETINAL ASTROCYTIC HAMARTOMA WITH VITREOUS HEMORRHAGE.

PubMed

Soeta, Megumi; Arai, Yusuke; Takahashi, Hidenori; Fujino, Yujiro; Tanabe, Tatsuro; Inoue, Yuji; Kawashima, Hidetoshi

2018-01-01

To report a case of retinal astrocytic hamartoma with vitreous hemorrhage and a hair pin-like vessel adhering to a posterior vitreous membrane. A 33-year-old man with a retinal astrocytic hamartoma presented with vitreous hemorrhage 5 times. Multimodal imaging, including fundus photography, fluorescein angiography, optical coherence tomography, and B-mode ultrasonography. Multimodal imaging demonstrated a novel hair pin-like vessel that adhered to the posterior vitreous membrane. Some cases of retinal astrocytic hamartoma with vitreous hemorrhage may be related to structure abnormalities of tumor vessels.

Ridge-branch-based blood vessel detection algorithm for multimodal retinal images

NASA Astrophysics Data System (ADS)

Li, Y.; Hutchings, N.; Knighton, R. W.; Gregori, G.; Lujan, B. J.; Flanagan, J. G.

2009-02-01

Automatic detection of retinal blood vessels is important to medical diagnoses and imaging. With the development of imaging technologies, various modals of retinal images are available. Few of currently published algorithms are applied to multimodal retinal images. Besides, the performance of algorithms with pathologies is expected to be improved. The purpose of this paper is to propose an automatic Ridge-Branch-Based (RBB) detection algorithm of blood vessel centerlines and blood vessels for multimodal retinal images (color fundus photographs, fluorescein angiograms, fundus autofluorescence images, SLO fundus images and OCT fundus images, for example). Ridges, which can be considered as centerlines of vessel-like patterns, are first extracted. The method uses the connective branching information of image ridges: if ridge pixels are connected, they are more likely to be in the same class, vessel ridge pixels or non-vessel ridge pixels. Thanks to the good distinguishing ability of the designed "Segment-Based Ridge Features", the classifier and its parameters can be easily adapted to multimodal retinal images without ground truth training. We present thorough experimental results on SLO images, color fundus photograph database and other multimodal retinal images, as well as comparison between other published algorithms. Results showed that the RBB algorithm achieved a good performance.

C-reactive protein and chitinase 3-like protein 1 as biomarkers of spatial redistribution of retinal blood vessels on digital retinal photography in patients with diabetic retinopathy.

PubMed

Cekić, Sonja; Cvetković, Tatjana; Jovanović, Ivan; Jovanović, Predrag; Pesić, Milica; Stanković Babić, Gordana; Milenković, Svetislav; Risimić, Dijana

2014-08-20

The aim of the study was to investigate the correlation between the levels of C-reactive protein (CRP) and chitinase 3-like protein 1 (YKL-40) in blood samples with morpohometric parameters of retinal blood vessels in patients with diabetic retinopathy. Blood laboratory examination of 90 patients included the measurement of glycemia, HbA1C, total cholesterol, LDL-C, HDL-C, triglycerides and CRP. Levels of YKL-40 were detected and measured in serum by ELISA (Micro VueYKL-40 EIA Kit, Quidel Corporation, San Diego, USA). YKL-40 correlated positively with diameter and negatively with number of retinal blood vessels. The average number of the blood vessels per retinal zone was significantly higher in the group of patients with mild non-proliferative diabetic retinopathy than in the group with severe form in the optic disc and all five retinal zones. The average outer diameter of the evaluated retinal zones and optic disc vessels was significantly higher in the group with severe compared to the group with mild diabetic retinopathy. Morphological analysis of the retinal vessels on digital fundus photography and correlation with YKL-40 may be valuable for the follow-up of diabetic retinopathy.

Bim expression in endothelial cells and pericytes is essential for regression of the fetal ocular vasculature.

PubMed

Wang, Shoujian; Zaitoun, Ismail S; Johnson, Ryan P; Jamali, Nasim; Gurel, Zafer; Wintheiser, Catherine M; Strasser, Andreas; Lindner, Volkhard; Sheibani, Nader; Sorenson, Christine M

2017-01-01

Apoptosis plays a central role in developmental and pathological angiogenesis and vessel regression. Bim is a pro-apoptotic Bcl-2 family member that plays a prominent role in both developmental and pathological ocular vessel regression, and neovascularization. Endothelial cells (EC) and pericytes (PC) each play unique roles during vascular development, maintenance and regression. We recently showed that germline deletion of Bim results in persistent hyaloid vasculature, increased retinal vascular density and prevents retinal vessel regression in response to hyperoxia. To determine whether retinal vascular regression is attributable to Bim expression in EC or PC we generated mice carrying a conditional Bim allele (BimFlox/Flox) and VE-cadherin-cre (BimEC mice) or Pdgfrb-cre (BimPC mice). BimEC and BimPC mice demonstrated attenuated hyaloid vessel regression and postnatal retinal vascular remodeling. We also observed decreased retinal vascular apoptosis and proliferation. Unlike global Bim -/- mice, mice conditionally lacking Bim in EC or PC underwent hyperoxia-mediated vessel obliteration and subsequent retinal neovascularization during oxygen-induced ischemic retinopathy similar to control littermates. Thus, understanding the cell autonomous role Bim plays in the retinal vascular homeostasis will give us new insight into how to modulate pathological retinal neovascularization and vessel regression to preserve vision.

Robust Hidden Markov Model based intelligent blood vessel detection of fundus images.

PubMed

Hassan, Mehdi; Amin, Muhammad; Murtza, Iqbal; Khan, Asifullah; Chaudhry, Asmatullah

2017-11-01

In this paper, we consider the challenging problem of detecting retinal vessel networks. Precise detection of retinal vessel networks is vital for accurate eye disease diagnosis. Most of the blood vessel tracking techniques may not properly track vessels in presence of vessels' occlusion. Owing to problem in sensor resolution or acquisition of fundus images, it is possible that some part of vessel may occlude. In this scenario, it becomes a challenging task to accurately trace these vital vessels. For this purpose, we have proposed a new robust and intelligent retinal vessel detection technique on Hidden Markov Model. The proposed model is able to successfully track vessels in the presence of occlusion. The effectiveness of the proposed technique is evaluated on publically available standard DRIVE dataset of the fundus images. The experiments show that the proposed technique not only outperforms the other state of the art methodologies of retinal blood vessels segmentation, but it is also capable of accurate occlusion handling in retinal vessel networks. The proposed technique offers better average classification accuracy, sensitivity, specificity, and area under the curve (AUC) of 95.7%, 81.0%, 97.0%, and 90.0% respectively, which shows the usefulness of the proposed technique. Copyright © 2017 Elsevier B.V. All rights reserved.

An easy method to differentiate retinal arteries from veins by spectral domain optical coherence tomography: retrospective, observational case series

PubMed Central

2014-01-01

Background Recently it was shown that retinal vessel diameters could be measured using spectral domain optical coherence tomography (OCT). It has also been suggested that retinal vessels manifest different features on spectral domain OCT (SD-OCT) depending on whether they are arteries or veins. Our study was aimed to present a reliable SD-OCT assisted method of differentiating retinal arteries from veins. Methods Patients who underwent circular OCT scans centred at the optic disc using a Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany) were retrospectively reviewed. Individual retinal vessels were identified on infrared reflectance (IR) images and given unique labels for subsequent grading. Vessel types (artery, vein or uncertain) assessed by IR and/or fluorescein angiography (FA) were referenced as ground truth. From OCT, presence/absence of the hyperreflective lower border reflectivity feature was assessed. Presence of this feature was considered indicative for retinal arteries and compared with the ground truth. Results A total of 452 vessels from 26 eyes of 18 patients were labelled and 398 with documented vessel type (302 by IR and 96 by FA only) were included in the study. Using SD-OCT, 338 vessels were assigned a final grade, of which, 86.4% (292 vessels) were classified correctly. Forty three vessels (15 arteries and 28 veins) that IR failed to differentiate were correctly classified by SD-OCT. When using only IR based ground truth for vessel type the SD-OCT based classification approach reached a sensitivity of 0.8758/0.9297, and a specificity of 0.9297/0.8758 for arteries/veins, respectively. Conclusion Our method was able to classify retinal arteries and veins with a commercially available SD-OCT alone, and achieved high classification performance. Paired with OCT based vessel measurements, our study has expanded the potential clinical implication of SD-OCT in evaluation of a variety of retinal and systemic vascular diseases. PMID:24884611

Improvement of retinal blood vessel detection by spur removal and Gaussian matched filtering compensation

NASA Astrophysics Data System (ADS)

Xiao, Di; Vignarajan, Janardhan; An, Dong; Tay-Kearney, Mei-Ling; Kanagasingam, Yogi

2016-03-01

Retinal photography is a non-invasive and well-accepted clinical diagnosis of ocular diseases. Qualitative and quantitative assessment of retinal images is crucial in ocular diseases related clinical application. In this paper, we proposed approaches for improving the quality of blood vessel detection based on our initial blood vessel detection methods. A blood vessel spur pruning method has been developed for removing the blood vessel spurs both on vessel medial lines and binary vessel masks, which are caused by artifacts and side-effect of Gaussian matched vessel enhancement. A Gaussian matched filtering compensation method has been developed for removing incorrect vessel branches in the areas of low illumination. The proposed approaches were applied and tested on the color fundus images from one publicly available database and our diabetic retinopathy screening dataset. A preliminary result has demonstrated the robustness and good performance of the proposed approaches and their potential application for improving retinal blood vessel detection.

Obesity, Blood Pressure, and Retinal Vessels: A Meta-analysis.

PubMed

Köchli, Sabrina; Endes, Katharina; Infanger, Denis; Zahner, Lukas; Hanssen, Henner

2018-06-01

Retinal vessel imaging is a noninvasive diagnostic tool used to evaluate cardiovascular risk. Childhood obesity and elevated blood pressure (BP) are associated with retinal microvascular alterations. To systematically review and meta-analyze associations between obesity, BP, and physical activity with retinal vessel diameters in children. We conducted a literature search through the databases of PubMed, Embase, Ovid, Web of Science, and the Cochrane Register of Controlled Trials. School- and population-based cross-sectional data. General information, study design, participants, exposure, and outcomes. A total of 1751 studies were found, and 30 full-text articles were analyzed for eligibility. Twenty-two articles (18 865 children and adolescents) were used for further assessment and reflection. Eleven articles were finally included in the meta-analysis. We found that a higher BMI is associated with narrower retinal arteriolar (pooled estimate effect size -0.37 [95% confidence interval (CI): -0.50 to -0.24]) and wider venular diameters (0.35 [95% CI: 0.07 to 0.63]). Systolic and diastolic BP are associated with retinal arteriolar narrowing (systolic BP: -0.63 [95% CI: -0.92 to -0.34]; diastolic BP: -0.60 [95% CI -0.95 to -0.25]). Increased physical activity and fitness are associated with favorable retinal vessel diameters. Long-term studies are needed to substantiate the prognostic relevance of retinal vessel diameters for cardiovascular risk in children. Our results indicate that childhood obesity, BP, and physical inactivity are associated with retinal microvascular abnormalities. Retinal vessel diameters seem to be sensitive microvascular biomarkers for cardiovascular risk stratification in children. Copyright © 2018 by the American Academy of Pediatrics.

A tool for computer-aided diagnosis of retinopathy of prematurity

NASA Astrophysics Data System (ADS)

Zhao, Zheen; Wallace, David K.; Freedman, Sharon F.; Aylward, Stephen R.

2008-03-01

In this paper we present improvements to a software application, named ROPtool, that aids in the timely and accurate detection and diagnosis of retinopathy of prematurity (ROP). ROP occurs in 68% of infants less than 1251 grams at birth, and it is a leading cause of blindness for prematurely born infants. The standard of care for its diagnosis is the subjective assessment of retinal vessel dilation and tortuosity. There is significant inter-observer variation in those assessments. ROPtool analyzes retinal images, extracts user-selected blood vessels from those images, and quantifies the tortuosity of those vessels. The presence of ROP is then gauged by comparing the tortuosity of an infant's retinal vessels with measures made from a clinical-standard image of severely tortuous retinal vessels. The presence of such tortuous retinal vessels is referred to as 'plus disease'. In this paper, a novel metric of tortuosity is proposed. From the ophthalmologist's point of view, the new metric is an improvement from our previously published algorithm, since it uses smooth curves instead of straight lines to simulate 'normal vessels'. Another advantage of the new ROPtool is that minimal user interactions are required. ROPtool utilizes a ridge traversal algorithm to extract retinal vessels. The algorithm reconstructs connectivity along a vessel automatically. This paper supports its claims by reporting ROC curves from a pilot study involving 20 retinal images. The areas under two ROC curves, from two experts in ROP, using the new metric to diagnose 'tortuosity sufficient for plus disease', varied from 0.86 to 0.91.

Improvement of retinal blood vessel detection using morphological component analysis.

PubMed

Imani, Elaheh; Javidi, Malihe; Pourreza, Hamid-Reza

2015-03-01

Detection and quantitative measurement of variations in the retinal blood vessels can help diagnose several diseases including diabetic retinopathy. Intrinsic characteristics of abnormal retinal images make blood vessel detection difficult. The major problem with traditional vessel segmentation algorithms is producing false positive vessels in the presence of diabetic retinopathy lesions. To overcome this problem, a novel scheme for extracting retinal blood vessels based on morphological component analysis (MCA) algorithm is presented in this paper. MCA was developed based on sparse representation of signals. This algorithm assumes that each signal is a linear combination of several morphologically distinct components. In the proposed method, the MCA algorithm with appropriate transforms is adopted to separate vessels and lesions from each other. Afterwards, the Morlet Wavelet Transform is applied to enhance the retinal vessels. The final vessel map is obtained by adaptive thresholding. The performance of the proposed method is measured on the publicly available DRIVE and STARE datasets and compared with several state-of-the-art methods. An accuracy of 0.9523 and 0.9590 has been respectively achieved on the DRIVE and STARE datasets, which are not only greater than most methods, but are also superior to the second human observer's performance. The results show that the proposed method can achieve improved detection in abnormal retinal images and decrease false positive vessels in pathological regions compared to other methods. Also, the robustness of the method in the presence of noise is shown via experimental result. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Imaging polarimetry and retinal blood vessel quantification at the epiretinal membrane

PubMed Central

Miura, Masahiro; Elsner, Ann E.; Cheney, Michael C.; Usui, Masahiko; Iwasaki, Takuya

2007-01-01

We evaluated a polarimetry method to enhance retinal blood vessels masked by the epiretinal membrane. Depolarized light images were computed by removing the polarization retaining light reaching the instrument and were compared with parallel polarized light images, average reflectance images, and the corresponding images at 514 nm. Contrasts were computed for retinal vessel profiles for arteries and veins. Contrasts were higher in the 514 nm images in normal eyes but higher in the depolarized light image in the eyes with epiretinal membranes. Depolarized light images were useful for examining the retinal vasculature in the presence of retinal disease. PMID:17429490

Automatic Tortuosity-Based Retinopathy of Prematurity Screening System

NASA Astrophysics Data System (ADS)

Sukkaew, Lassada; Uyyanonvara, Bunyarit; Makhanov, Stanislav S.; Barman, Sarah; Pangputhipong, Pannet

Retinopathy of Prematurity (ROP) is an infant disease characterized by increased dilation and tortuosity of the retinal blood vessels. Automatic tortuosity evaluation from retinal digital images is very useful to facilitate an ophthalmologist in the ROP screening and to prevent childhood blindness. This paper proposes a method to automatically classify the image into tortuous and non-tortuous. The process imitates expert ophthalmologists' screening by searching for clearly tortuous vessel segments. First, a skeleton of the retinal blood vessels is extracted from the original infant retinal image using a series of morphological operators. Next, we propose to partition the blood vessels recursively using an adaptive linear interpolation scheme. Finally, the tortuosity is calculated based on the curvature of the resulting vessel segments. The retinal images are then classified into two classes using segments characterized by the highest tortuosity. For an optimal set of training parameters the prediction is as high as 100%.

Characterisation of Feature Points in Eye Fundus Images

NASA Astrophysics Data System (ADS)

Calvo, D.; Ortega, M.; Penedo, M. G.; Rouco, J.

The retinal vessel tree adds decisive knowledge in the diagnosis of numerous opthalmologic pathologies such as hypertension or diabetes. One of the problems in the analysis of the retinal vessel tree is the lack of information in terms of vessels depth as the image acquisition usually leads to a 2D image. This situation provokes a scenario where two different vessels coinciding in a point could be interpreted as a vessel forking into a bifurcation. That is why, for traking and labelling the retinal vascular tree, bifurcations and crossovers of vessels are considered feature points. In this work a novel method for these retinal vessel tree feature points detection and classification is introduced. The method applies image techniques such as filters or thinning to obtain the adequate structure to detect the points and sets a classification of these points studying its environment. The methodology is tested using a standard database and the results show high classification capabilities.

A Morphological Hessian Based Approach for Retinal Blood Vessels Segmentation and Denoising Using Region Based Otsu Thresholding

PubMed Central

BahadarKhan, Khan; A Khaliq, Amir; Shahid, Muhammad

2016-01-01

Diabetic Retinopathy (DR) harm retinal blood vessels in the eye causing visual deficiency. The appearance and structure of blood vessels in retinal images play an essential part in the diagnoses of an eye sicknesses. We proposed a less computational unsupervised automated technique with promising results for detection of retinal vasculature by using morphological hessian based approach and region based Otsu thresholding. Contrast Limited Adaptive Histogram Equalization (CLAHE) and morphological filters have been used for enhancement and to remove low frequency noise or geometrical objects, respectively. The hessian matrix and eigenvalues approach used has been in a modified form at two different scales to extract wide and thin vessel enhanced images separately. Otsu thresholding has been further applied in a novel way to classify vessel and non-vessel pixels from both enhanced images. Finally, postprocessing steps has been used to eliminate the unwanted region/segment, non-vessel pixels, disease abnormalities and noise, to obtain a final segmented image. The proposed technique has been analyzed on the openly accessible DRIVE (Digital Retinal Images for Vessel Extraction) and STARE (STructured Analysis of the REtina) databases along with the ground truth data that has been precisely marked by the experts. PMID:27441646

Reproducibility of Spectral Domain Optical Coherence Tomography Retinal Thickness Measurements and Conversion to Equivalent Time Domain Metrics in Diabetic Macular Edema

PubMed Central

Bressler, Susan B.; Edwards, Allison R.; Chalam, Kakarla V.; Bressler, Neil M.; Glassman, Adam R.; Jaffe, Glenn J.; Melia, Michele; Saggau, David D.; Plous, Oren Z.

2014-01-01

Importance Advances in retinal imaging have led to the development of optical coherence tomography (OCT) instruments that incorporate spectral domain (SD) technology. Understanding measurement variability and relationships between retinal thickness measurements obtained on different machines is critical for proper use in clinical trials and clinical settings. Objectives Evaluate reproducibility of retinal thickness measurements from OCT images obtained by time domain (TD) (Zeiss Stratus) and SD (Zeiss Cirrus and Heidelberg Spectralis) instruments and formulate equations to convert retinal thickness measurements from SD-OCT to equivalent values on TD-OCT. Design Cross-sectional observational study. Each study eye underwent two replicate Stratus scans followed by two replicate Cirrus or Spectralis (real time image registration utilized) scans centered on the fovea. Setting Private and institutional practices Participants Diabetic persons with at least one eye with central-involved diabetic macular edema (DME), defined as Stratus central subfield thickness (CST)≥250μm. An additional normative cohort, individuals with diabetes but without DME, was enrolled. Main Outcome Measure(s) OCT CST and macular volume Results The Bland-Altman coefficient of repeatability for relative change in CST (the degree of change that could be expected from measurement variability) was lower on Spectralis compared with Stratus and Cirrus scans (7%, 12–15%, and 14%, respectively). For each cohort, the initial Stratus CST was within 10% of the replicate Stratus measurement 92% of the time; the conversion equations predicted a Stratus CST within 10% of the observed thickness 86% and 89% of the time for Stratus/Cirrus and Stratus/Spectralis groups, respectively. The Bland-Altman limits of agreement for relative change in CST between machines (the degree of change that could be expected from measurement variability, combined within and between instrument variability) were 21% for Cirrus and 19% for Spectralis, comparing predicted versus actual Stratus measurement. Conclusions and Relevance Reproducibility appears better on Spectralis than Cirrus and Stratus. Conversion equations to transform Cirrus or Spectralis measurements to Stratus-equivalent values, within 10% of the observed Stratus thickness values, appear feasible. CST changes beyond 10% when using the same machine or 20% when switching machines, after conversion to Stratus equivalents, are likely due to a change in retinal thickness and not measurement error. PMID:25058482

Fast vessel segmentation in retinal images using multi-scale enhancement and second-order local entropy

NASA Astrophysics Data System (ADS)

Yu, H.; Barriga, S.; Agurto, C.; Zamora, G.; Bauman, W.; Soliz, P.

2012-03-01

Retinal vasculature is one of the most important anatomical structures in digital retinal photographs. Accurate segmentation of retinal blood vessels is an essential task in automated analysis of retinopathy. This paper presents a new and effective vessel segmentation algorithm that features computational simplicity and fast implementation. This method uses morphological pre-processing to decrease the disturbance of bright structures and lesions before vessel extraction. Next, a vessel probability map is generated by computing the eigenvalues of the second derivatives of Gaussian filtered image at multiple scales. Then, the second order local entropy thresholding is applied to segment the vessel map. Lastly, a rule-based decision step, which measures the geometric shape difference between vessels and lesions is applied to reduce false positives. The algorithm is evaluated on the low-resolution DRIVE and STARE databases and the publicly available high-resolution image database from Friedrich-Alexander University Erlangen-Nuremberg, Germany). The proposed method achieved comparable performance to state of the art unsupervised vessel segmentation methods with a competitive faster speed on the DRIVE and STARE databases. For the high resolution fundus image database, the proposed algorithm outperforms an existing approach both on performance and speed. The efficiency and robustness make the blood vessel segmentation method described here suitable for broad application in automated analysis of retinal images.

3D Reconstruction of the Retinal Arterial Tree Using Subject-Specific Fundus Images

NASA Astrophysics Data System (ADS)

Liu, D.; Wood, N. B.; Xu, X. Y.; Witt, N.; Hughes, A. D.; Samcg, Thom

Systemic diseases, such as hypertension and diabetes, are associated with changes in the retinal microvasculature. Although a number of studies have been performed on the quantitative assessment of the geometrical patterns of the retinal vasculature, previous work has been confined to 2 dimensional (2D) analyses. In this paper, we present an approach to obtain a 3D reconstruction of the retinal arteries from a pair of 2D retinal images acquired in vivo. A simple essential matrix based self-calibration approach was employed for the "fundus camera-eye" system. Vessel segmentation was performed using a semi-automatic approach and correspondence between points from different images was calculated. The results of 3D reconstruction show the centreline of retinal vessels and their 3D curvature clearly. Three-dimensional reconstruction of the retinal vessels is feasible and may be useful in future studies of the retinal vasculature in disease.

An Eye Oximeter for Combat Casualty Care

DTIC Science & Technology

1999-12-01

monitoring (e.g., retinitis pigmentosa , retinal detachment, macular degeneration, diabetic retinopathy, etc.). Recently, scanning laser microscopy...and UAH is generating instrumentation and scientific data suggesting that retinal vessel oxygen saturations (both arterial and venous) may be used...and developing the techniques required to accurately measure retinal large vessel oxygen saturations. As this work is being accomplished we have used

Retinal blood vessel segmentation using fully convolutional network with transfer learning.

PubMed

Jiang, Zhexin; Zhang, Hao; Wang, Yi; Ko, Seok-Bum

2018-04-26

Since the retinal blood vessel has been acknowledged as an indispensable element in both ophthalmological and cardiovascular disease diagnosis, the accurate segmentation of the retinal vessel tree has become the prerequisite step for automated or computer-aided diagnosis systems. In this paper, a supervised method is presented based on a pre-trained fully convolutional network through transfer learning. This proposed method has simplified the typical retinal vessel segmentation problem from full-size image segmentation to regional vessel element recognition and result merging. Meanwhile, additional unsupervised image post-processing techniques are applied to this proposed method so as to refine the final result. Extensive experiments have been conducted on DRIVE, STARE, CHASE_DB1 and HRF databases, and the accuracy of the cross-database test on these four databases is state-of-the-art, which also presents the high robustness of the proposed approach. This successful result has not only contributed to the area of automated retinal blood vessel segmentation but also supports the effectiveness of transfer learning when applying deep learning technique to medical imaging. Copyright © 2018 Elsevier Ltd. All rights reserved.

Ocular Fundus Photography as a Tool to Study Stroke and Dementia.

PubMed

Cheung, Carol Y; Chen, Christopher; Wong, Tien Y

2015-10-01

Although cerebral small vessel disease has been linked to stroke and dementia, due to limitations of current neuroimaging technology, direct in vivo visualization of changes in the cerebral small vessels (e.g., cerebral arteriolar narrowing, tortuous microvessels, blood-brain barrier damage, capillary microaneurysms) is difficult to achieve. As the retina and the brain share similar embryological origin, anatomical features, and physiologic properties with the cerebral small vessels, the retinal vessels offer a unique and easily accessible "window" to study the correlates and consequences of cerebral small vessel diseases in vivo. The retinal microvasculature can be visualized, quantified and monitored noninvasively using ocular fundus photography. Recent clinic- and population-based studies have demonstrated a close link between retinal vascular changes seen on fundus photography and stroke and dementia, suggesting that ocular fundus photography may provide insights to the contribution of microvascular disease to stroke and dementia. In this review, we summarize current knowledge on retinal vascular changes, such as retinopathy and changes in retinal vascular measures with stroke and dementia as well as subclinical makers of cerebral small vessel disease, and discuss the possible clinical implications of these findings in neurology. Studying pathologic changes of retinal blood vessels may be useful for understanding the etiology of various cerebrovascular conditions; hence, ocular fundus photography can be potentially translated into clinical practice. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Summarising the retinal vascular calibres in healthy, diabetic and diabetic retinopathy eyes.

PubMed

Leontidis, Georgios; Al-Diri, Bashir; Hunter, Andrew

2016-05-01

Retinal vessel calibre has been found to be an important biomarker of several retinal diseases, including diabetic retinopathy (DR). Quantifying the retinal vessel calibres is an important step for estimating the central retinal artery and vein equivalents. In this study, an alternative method to the already established branching coefficient (BC) is proposed for summarising the vessel calibres in retinal junctions. This new method combines the mean diameter ratio with an alternative to Murray׳s cube law exponent, derived by the fractal dimension,experimentally, and the branch exponent of cerebral vessels, as has been suggested in previous studies with blood flow modelling. For the above calculations, retinal images from healthy, diabetic and DR subjects were used. In addition, the above method was compared with the BC and was also applied to the evaluation of arteriovenous ratio as a biomarker of progression from diabetes to DR in four consecutive years, i.e. three/two/one years before the onset of DR and the first year of DR. Moreover, the retinal arteries and veins around the optic nerve head were also evaluated. The new approach quantifies the vessels more accurately. The decrease in terms of the mean absolute percentage error was between 0.24% and 0.49%, extending at the same time the quantification beyond healthy subjects. Copyright © 2016 Elsevier Ltd. All rights reserved.

Linking Retinal Microvasculature Features With Severity of Diabetic Retinopathy Using Optical Coherence Tomography Angiography.

PubMed

Bhanushali, Devanshi; Anegondi, Neha; Gadde, Santosh G K; Srinivasan, Priya; Chidambara, Lavanya; Yadav, Naresh Kumar; Sinha Roy, Abhijit

2016-07-01

To correlate retinal vascular features with severity and systemic indicators of diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA). A total of 209 eyes of 122 type 2 diabetes mellitus patients with DR and 60 eyes of 31 normal Indian subjects underwent OCTA imaging. The diabetic retinopathy patients were graded as having either nonproliferative diabetic retinopathy (NPDR: mild, moderate, and severe NPDR using Early Treatment Diabetic Retinopathy Study classification) or proliferative diabetic retinopathy (PDR). Local fractal analysis was applied to the superficial and deep retinal OCTA images. Foveal avascular zone area (FAZ in mm2); vessel density (%); spacing between large vessels (%); and spacing between small vessels (%) were analyzed. Sensitivity and specificity of vascular parameters were assessed with receiver operating characteristics (ROC) curve. Normal eyes had a significantly lower FAZ area, higher vessel density, and lower spacing between large and small vessels compared with DR grades (P < 0.001). In the superficial layer, PDR and severe NPDR had higher spacing between large vessels than mild and moderate NPDR (P = 0.04). However, mild NPDR had higher spacing between the small vessels (P < 0.001). Spacing between the large vessels in the superficial retinal layer correlated positively with HbA1c (r = 0.25, P = 0.03); fasting (r = 0.23, P = 0.02); and postprandial (r = 0.26, P = 0.03) blood sugar. The same spacing in the deep retinal vascular plexus had the highest area under the ROC curve (0.99 ± 0.01) and was uniformly elevated in all diabetic eyes (P > 0.05). Spacing between the large vessels in the superficial and deep retinal layers had superior diagnostic performance than overall vessel density.

Automated method for the identification and analysis of vascular tree structures in retinal vessel network

NASA Astrophysics Data System (ADS)

Joshi, Vinayak S.; Garvin, Mona K.; Reinhardt, Joseph M.; Abramoff, Michael D.

2011-03-01

Structural analysis of retinal vessel network has so far served in the diagnosis of retinopathies and systemic diseases. The retinopathies are known to affect the morphologic properties of retinal vessels such as course, shape, caliber, and tortuosity. Whether the arteries and the veins respond to these changes together or in tandem has always been a topic of discussion. However the diseases such as diabetic retinopathy and retinopathy of prematurity have been diagnosed with the morphologic changes specific either to arteries or to veins. Thus a method describing the separation of retinal vessel trees imaged in a two dimensional color fundus image may assist in artery-vein classification and quantitative assessment of morphologic changes particular to arteries or veins. We propose a method based on mathematical morphology and graph search to identify and label the retinal vessel trees, which provides a structural mapping of vessel network in terms of each individual primary vessel, its branches and spatial positions of branching and cross-over points. The method was evaluated on a dataset of 15 fundus images resulting into an accuracy of 92.87 % correctly assigned vessel pixels when compared with the manual labeling of separated vessel trees. Accordingly, the structural mapping method performs well and we are currently investigating its potential in evaluating the characteristic properties specific to arteries or veins.

Automated artery-venous classification of retinal blood vessels based on structural mapping method

NASA Astrophysics Data System (ADS)

Joshi, Vinayak S.; Garvin, Mona K.; Reinhardt, Joseph M.; Abramoff, Michael D.

2012-03-01

Retinal blood vessels show morphologic modifications in response to various retinopathies. However, the specific responses exhibited by arteries and veins may provide a precise diagnostic information, i.e., a diabetic retinopathy may be detected more accurately with the venous dilatation instead of average vessel dilatation. In order to analyze the vessel type specific morphologic modifications, the classification of a vessel network into arteries and veins is required. We previously described a method for identification and separation of retinal vessel trees; i.e. structural mapping. Therefore, we propose the artery-venous classification based on structural mapping and identification of color properties prominent to the vessel types. The mean and standard deviation of each of green channel intensity and hue channel intensity are analyzed in a region of interest around each centerline pixel of a vessel. Using the vector of color properties extracted from each centerline pixel, it is classified into one of the two clusters (artery and vein), obtained by the fuzzy-C-means clustering. According to the proportion of clustered centerline pixels in a particular vessel, and utilizing the artery-venous crossing property of retinal vessels, each vessel is assigned a label of an artery or a vein. The classification results are compared with the manually annotated ground truth (gold standard). We applied the proposed method to a dataset of 15 retinal color fundus images resulting in an accuracy of 88.28% correctly classified vessel pixels. The automated classification results match well with the gold standard suggesting its potential in artery-venous classification and the respective morphology analysis.

Increased-resolution OCT thickness mapping of the human macula: a statistically based registration.

PubMed

Bernardes, Rui; Santos, Torcato; Cunha-Vaz, José

2008-05-01

To describe the development of a technique that enhances spatial resolution of retinal thickness maps of the Stratus OCT (Carl Zeiss Meditec, Inc., Dublin, CA). A retinal thickness atlas (RT-atlas) template was calculated, and a macular coordinate system was established, to pursue this objective. The RT-atlas was developed from principal component analysis of retinal thickness analyzer (RTA) maps acquired from healthy volunteers. The Stratus OCT radial thickness measurements were registered on the RT-atlas, from which an improved macular thickness map was calculated. Thereafter, Stratus OCT circular scans were registered on the previously calculated map to enhance spatial resolution. The developed technique was applied to Stratus OCT thickness data from healthy volunteers and from patients with diabetic retinopathy (DR) or age-related macular degeneration (AMD). Results showed that for normal, or close to normal, macular thickness maps from healthy volunteers and patients with DR, this technique can be an important aid in determining retinal thickness. Efforts are under way to improve the registration of retinal thickness data in patients with AMD. The developed technique enhances the evaluation of data acquired by the Stratus OCT, helping the detection of early retinal thickness abnormalities. Moreover, a normative database of retinal thickness measurements gained from this technique, as referenced to the macular coordinate system, can be created without errors induced by missed fixation and eye tilt.

Lack of differences in the regional variation of oxygen saturation in larger retinal vessels in diabetic maculopathy and proliferative diabetic retinopathy.

PubMed

Jørgensen, Christina Mørup; Bek, Toke

2017-06-01

Diabetic retinopathy is characterised by morphological lesions in the ocular fundus related to disturbances in retinal blood flow. The two vision threatening forms of retinopathy show specific patterns of distribution of retinal lesions with proliferative diabetic retinopathy (PDR) developing secondary to ischaemia and hypoxia in the retinal periphery and diabetic maculopathy (DM) developing secondary to hyperperfusion and increased vascular permeability in the macular area. These differences in the distribution of retinal lesions might be reflected in regional differences in oxygen saturation in the larger retinal vessels. Dual-wavelength retinal oximetry was performed in 30 normal persons, 30 patients with DM and 30 patients with PDR, and the oxygen saturation was measured in peripapillary vessels supplying the four retinal quadrants and in branches from the upper temporal arcades supplying, respectively, the macular area and the retinal periphery. The overall oxygen saturation was significantly higher in diabetic patients than in normal persons and the arteriovenous (AV) saturation difference significantly lower in the patients with DM. The regional variation in oxygen saturation was similar in the three studied groups with a decreasing saturation from the upper nasal through the lower nasal, lower temporal and the upper temporal peripapillary vessels, and with a significantly higher oxygen saturation in venules draining the macular area than in venules draining the retinal periphery. The regional differences in retinal lesions in vision threatening diabetic retinopathy are not reflected in regional differences in the oxygen saturation of larger retinal vessels. The development of vision threatening diabetic retinopathy depends on other factors, such as, for example, regional differences in the retinal microcirculation. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Retinal vessel tortuosity measures and their applications.

PubMed

Kalitzeos, Angelos A; Lip, Gregory Y H; Heitmar, Rebekka

2013-01-01

Structural retinal vascular characteristics, such as vessel calibers, tortuosity and bifurcation angles are increasingly quantified in an objective manner, slowly replacing subjective qualitative disease classification schemes. This paper provides an overview of the current methodologies and calculations used to compute retinal vessel tortuosity. We set out the different parameter calculations and provide an insight into the clinical applications, while critically reviewing its pitfalls and shortcomings. Copyright © 2012 Elsevier Ltd. All rights reserved.

Segmentation of Retinal Blood Vessels Based on Cake Filter

PubMed Central

Bao, Xi-Rong; Ge, Xin; She, Li-Huang; Zhang, Shi

2015-01-01

Segmentation of retinal blood vessels is significant to diagnosis and evaluation of ocular diseases like glaucoma and systemic diseases such as diabetes and hypertension. The retinal blood vessel segmentation for small and low contrast vessels is still a challenging problem. To solve this problem, a new method based on cake filter is proposed. Firstly, a quadrature filter band called cake filter band is made up in Fourier field. Then the real component fusion is used to separate the blood vessel from the background. Finally, the blood vessel network is got by a self-adaption threshold. The experiments implemented on the STARE database indicate that the new method has a better performance than the traditional ones on the small vessels extraction, average accuracy rate, and true and false positive rate. PMID:26636095

Diameter of retinal vessels in patients with diabetic macular edema is not altered by intravitreal ranibizumab (lucentis).

PubMed

Terai, Naim; Haustein, Michael; Siegel, Anastasia; Stodtmeister, Richard; Pillunat, Lutz E; Sandner, Dirk

2014-07-01

To investigate the effect(s) of intravitreally injected ranibizumab on retinal vessel diameter in patients with diabetic macular edema. Participants of this prospective study were 14 men and 16 women (30 eyes) aged 60 ± 11 years (mean ± standard deviation), all with clinically significant diabetic macular edema. Treatment comprised 3 intravitreal injections of ranibizumab given at 4-week intervals. Examinations were conducted before the first (baseline), before the second (Month 1), before the third (Month 2) injections, and 3 months after baseline (Month 3). Measured parameters included systemic blood pressure, static retinal vessel analysis (central retinal artery equivalent and central retinal vein equivalent), and dynamic retinal vessel analysis, as measured by the change in vessel diameter in response to flicker stimulation during three measurement cycles. Flicker stimulation was accomplished using a 50-second baseline recording, followed by an online measurement during 20-second flicker stimulation and 80-second online measurements in both arteriolar and venular vessel segments. Static retinal vessel analysis showed a reduction of central retinal artery equivalent from 186.25 ± 51.40 μm (baseline) to 173.20 ± 22.2 μm (Month 1), to 174.30 ± 27.30 μm (Month 2), and to 170.56 ± 22.89 μm (Month 3), none of which was statistically significant (P = 0.23, 0.12, and 0.14, respectively). Central retinal vein equivalent was reduced from 216.21 ± 25.0 μm (baseline) to 214.48 ± 25.4 μm (Month 1), to 214.80 ± 24.30 μm (Month 2), and to 211.41 ± 24.30 μm (Month 3), revealing no statistically significant differences between examination time points (P = 0.54, 0.06, and 0.24, respectively). Dynamic vessel analysis yielded a mean retinal arterial diameter change of +1.47% ± 2.3 (baseline), +1.91% ± 2.5 (Month 1), +1.76% ± 2.2 (Month 2), and +1.66% ± 2.1 (Month 3), none of which showed statistically significant differences (P = 0.32, 0.49, and 0.70, respectively). Mean retinal venous diameter changes were +3.15% ± 1.7 (baseline), +3.7% ± 2.3 (Month 1), +4.0% ± 2.0 (Month 2), and +4.95% ± 1.9 (Month 3), none of which showed statistically significant differences (P = 0.12, 0.17, and 0.14, respectively). Central retinal thickness, as measured by spectral domain optical coherence tomography, decreased significantly from 435.2 ± 131.8 μm (baseline) to 372.3 ± 142.8 μm (Month 3), P = 0.01. Regression analysis of arteriolar and venular diameters indicated that there was no significant correlation between these 2 parameters (r = 0.053; P = 0.835 and r = 0.06; P = 0.817, respectively). Also, no significant correlation was observed between the difference in the central retinal thickness and change in arteriolar or venular dilatation (r = 0.291, P = 0.241 and r = 0.06, P = 0.435, respectively). Intravitreally applied ranibizumab did not significantly affect retinal vessel diameter in patients with diabetic macular edema. Decline in the central foveal thickness after ranibizumab therapy, as measured by spectral domain optical coherence tomography, was not linked to any change in retinal vessel diameter or dilatatory response, neither for arterioles nor venules.

Small and large vessel disease in persons with unrecognized compared to recognized myocardial infarction: The Tromsø Study 2007-2008.

PubMed

Øhrn, Andrea Milde; Schirmer, Henrik; von Hanno, Therese; Mathiesen, Ellisiv B; Arntzen, Kjell Arne; Bertelsen, Geir; Njølstad, Inger; Løchen, Maja-Lisa; Wilsgaard, Tom; Bairey Merz, C Noel; Lindekleiv, Haakon

2018-02-15

Unrecognized myocardial infarction (MI) is a frequent condition with unknown underlying reason. We hypothesized the lack of recognition of MI is related to pathophysiology, specifically differences in underlying small and large vessel disease. 6128 participants were examined with retinal photography, ultrasound of the carotid artery and a 12‑lead electrocardiography (ECG). Small vessel disease was defined as narrower retinal arterioles and/or wider retinal venules measured on retinal photographs. Large vessel disease was defined as carotid artery pathology. We defined unrecognized MI as ECG-evidence of MI without a clinically recognized event. We analyzed the cross-sectional relationship between MI recognition and markers of small and large vessel disease, adjusted for age and sex. Unrecognized MI was present in 502 (8.2%) and recognized MI in 326 (5.3%) of the 6128 participants. Compared to recognized MI, unrecognized MI was associated with small vessel disease indicated by narrower retinal arterioles (OR 1.66, 95% CI 1.05-2.62, highest vs. lowest quartile). Unrecognized MI was less associated with wider retinal venules (OR 0.55, 95% CI 0.35-0.87, lowest vs. highest quartile). Compared to recognized MI, unrecognized MI was less associated with large vessel disease indicated by presence of plaque in the carotid artery (OR for presence of carotid artery plaque in unrecognized MI 0.51, 95% CI 0.37-0.69). No significant sex interaction was present. Unrecognized MI was more associated with small vessel disease and less associated with large vessel disease compared to recognized MI. These findings suggest that the pathophysiology behind unrecognized and recognized MI may differ. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

An efficient algorithm for measurement of retinal vessel diameter from fundus images based on directional filtering

NASA Astrophysics Data System (ADS)

Wang, Xuchu; Niu, Yanmin

2011-02-01

Automatic measurement of vessels from fundus images is a crucial step for assessing vessel anomalies in ophthalmological community, where the change in retinal vessel diameters is believed to be indicative of the risk level of diabetic retinopathy. In this paper, a new retinal vessel diameter measurement method by combining vessel orientation estimation and filter response is proposed. Its interesting characteristics include: (1) different from the methods that only fit the vessel profiles, the proposed method extracts more stable and accurate vessel diameter by casting this problem as a maximal response problem of a variation of Gabor filter; (2) the proposed method can directly and efficiently estimate the vessel's orientation, which is usually captured by time-consuming multi-orientation fitting techniques in many existing methods. Experimental results shows that the proposed method both retains the computational simplicity and achieves stable and accurate estimation results.

Feasibility study on retinal vascular bypass surgery in isolated arterially perfused caprine eye model

PubMed Central

Chen, Y; Wu, W; Zhang, X; Fan, W; Shen, L

2011-01-01

Purpose To investigate the feasibility of bypassing occluded segments of retinal venous main vessels in isolated, arterially perfused caprine eyes via the closed-sky vitrectomy approach using keratoprosthesis. Methods Isolated caprine eyes were used in this study. For each eye, the retinal vessel was perfused by Krebs solution via ophthalmic artery, and pars plana vitrectomy was performed using temporary keratoprosthesis. All retinal micro-vascular maneuvers were performed in a closed-sky eyeball. The main retinal vein was blocked by endodiathermy at the site of the vessel's first branching. Two openings, several millimeters apart, were created by vascular punctures in both the main vein and its branch vein wall straddling the induced occluded segment. Catheterization was achieved using a flexible polyimide tube, with each end inserted into the vessel wall opening. A sealed connection between the vessel and the tube was obtained by endodiathermy. Bypass of the occluded retinal vein segment was thus achieved, and the patency of this vascular bypass was confirmed by intravascular staining. Results Puncturing, catheterization, and endodiathermy were viable by closed-sky approach using keratoprosthesis. Bypassing of the occluded retinal main vein segment was accomplished with the combination of these maneuvers. Good results were obtained in 23 of 38 (60%) caprine eyes. Conclusions This study demonstrated that bypassing the occluded segment of retinal main vein can be successfully performed in a closed-sky eyeball model of isolated, arterially perfused caprine eye. This early work indicated that the more advanced retinal vascular bypass surgery in in vivo eye may be feasible in the future. PMID:21921946

Visible-light OCT to quantify retinal oxygen metabolism (Conference Presentation)

NASA Astrophysics Data System (ADS)

Zhang, Hao F.; Yi, Ji; Chen, Siyu; Liu, Wenzhong; Soetikno, Brian T.

2016-03-01

We explored, both numerically and experimentally, whether OCT can be a good candidate to accurately measure retinal oxygen metabolism. We first used statistical methods to numerically simulate photon transport in the retina to mimic OCT working under different spectral ranges. Then we analyze accuracy of OCT oximetry subject to parameter variations such as vessel size, pigmentation, and oxygenation. We further developed an experimental OCT system based on the spectral range identified by our simulation work. We applied the newly developed OCT to measure both retinal hemoglobin oxygen saturation (sO2) and retinal retinal flow. After obtaining the retinal sO2 and blood velocity, we further measured retinal vessel diameter and calculated the retinal oxygen metabolism rate (MRO2). To test the capability of our OCT, we imaged wild-type Long-Evans rats ventilated with both normal air and air mixtures with various oxygen concentrations. Our simulation suggested that OCT working within visible spectral range is able to provide accurate measurement of retinal MRO2 using inverse Fourier transform spectral reconstruction. We called this newly developed technology vis-OCT, and showed that vis-OCT was able to measure the sO2 value in every single major retinal vessel around the optical disk as well as in micro retinal vessels. When breathing normal air, the averaged sO2 in arterial and venous blood in Long-Evans rats was measured to be 95% and 72%, respectively. When we challenge the rats using air mixtures with different oxygen concentrations, vis-OCT measurement followed analytical models of retinal oxygen diffusion and pulse oximeter well.

Dense concentric circle scanning protocol for measuring pulsatile retinal blood flow in rats with Doppler optical coherence tomography

NASA Astrophysics Data System (ADS)

Tan, Bingyao; Hosseinaee, Zohreh; Bizheva, Kostadinka

2017-11-01

The variability in the spatial orientation of retinal blood vessels near the optic nerve head (ONH) results in imprecision of the measured Doppler angle and therefore the pulsatile blood flow (BF), when those parameters are evaluated using Doppler OCT imaging protocols based on dual-concentric circular scans. Here, we utilized a dense concentric circle scanning protocol and evaluated its precision for measuring pulsatile retinal BF in rats for different numbers of the circular scans. An spectral domain optical coherence tomography (SD-OCT) system operating in the 1060-nm spectral range with image acquisition rate of 47,000 A-scans/s was used to acquire concentric circular scans centered at the rat's ONH, with diameters ranging from 0.8 to 1.0 mm. A custom, automatic blood vessel segmentation algorithm was used to track the spatial orientation of the retinal blood vessels in three dimensions, evaluate the spatially dependent Doppler angle and calculate more accurately the axial BF for each major retinal blood vessel. Metrics such as retinal BF, pulsatility index, and resistance index were evaluated for each and all of the major retinal blood vessels. The performance of the proposed dense concentric circle scanning protocols was compared with that of the dual-circle scanning protocol. Results showed a 3.8±2.2 deg difference in the Doppler angle calculation between the two approaches, which resulted in ˜7% difference in the calculated retinal BF.

A robust technique based on VLM and Frangi filter for retinal vessel extraction and denoising.

PubMed

Khan, Khan Bahadar; Khaliq, Amir A; Jalil, Abdul; Shahid, Muhammad

2018-01-01

The exploration of retinal vessel structure is colossally important on account of numerous diseases including stroke, Diabetic Retinopathy (DR) and coronary heart diseases, which can damage the retinal vessel structure. The retinal vascular network is very hard to be extracted due to its spreading and diminishing geometry and contrast variation in an image. The proposed technique consists of unique parallel processes for denoising and extraction of blood vessels in retinal images. In the preprocessing section, an adaptive histogram equalization enhances dissimilarity between the vessels and the background and morphological top-hat filters are employed to eliminate macula and optic disc, etc. To remove local noise, the difference of images is computed from the top-hat filtered image and the high-boost filtered image. Frangi filter is applied at multi scale for the enhancement of vessels possessing diverse widths. Segmentation is performed by using improved Otsu thresholding on the high-boost filtered image and Frangi's enhanced image, separately. In the postprocessing steps, a Vessel Location Map (VLM) is extracted by using raster to vector transformation. Postprocessing steps are employed in a novel way to reject misclassified vessel pixels. The final segmented image is obtained by using pixel-by-pixel AND operation between VLM and Frangi output image. The method has been rigorously analyzed on the STARE, DRIVE and HRF datasets.

Doppler optical coherence tomography of retinal circulation.

PubMed

Tan, Ou; Wang, Yimin; Konduru, Ranjith K; Zhang, Xinbo; Sadda, SriniVas R; Huang, David

2012-09-18

Noncontact retinal blood flow measurements are performed with a Fourier domain optical coherence tomography (OCT) system using a circumpapillary double circular scan (CDCS) that scans around the optic nerve head at 3.40 mm and 3.75 mm diameters. The double concentric circles are performed 6 times consecutively over 2 sec. The CDCS scan is saved with Doppler shift information from which flow can be calculated. The standard clinical protocol calls for 3 CDCS scans made with the OCT beam passing through the superonasal edge of the pupil and 3 CDCS scan through the inferonal pupil. This double-angle protocol ensures that acceptable Doppler angle is obtained on each retinal branch vessel in at least 1 scan. The CDCS scan data, a 3-dimensional volumetric OCT scan of the optic disc scan, and a color photograph of the optic disc are used together to obtain retinal blood flow measurement on an eye. We have developed a blood flow measurement software called "Doppler optical coherence tomography of retinal circulation" (DOCTORC). This semi-automated software is used to measure total retinal blood flow, vessel cross section area, and average blood velocity. The flow of each vessel is calculated from the Doppler shift in the vessel cross-sectional area and the Doppler angle between the vessel and the OCT beam. Total retinal blood flow measurement is summed from the veins around the optic disc. The results obtained at our Doppler OCT reading center showed good reproducibility between graders and methods (<10%). Total retinal blood flow could be useful in the management of glaucoma, other retinal diseases, and retinal diseases. In glaucoma patients, OCT retinal blood flow measurement was highly correlated with visual field loss (R(2)>0.57 with visual field pattern deviation). Doppler OCT is a new method to perform rapid, noncontact, and repeatable measurement of total retinal blood flow using widely available Fourier-domain OCT instrumentation. This new technology may improve the practicality of making these measurements in clinical studies and routine clinical practice.

Optical Coherence Tomography Angiography of Pigmented Paravenous Retinochoroidal Atrophy.

PubMed

Cicinelli, Maria Vittoria; Giuffrè, Chiara; Rabiolo, Alessandro; Parodi, Maurizio Battaglia; Bandello, Francesco

2018-05-01

A 58-year-old man with bilateral pigmented paravenous retinochoroidal atrophy (PPRCA) associated with macular coloboma in the right eye underwent color fundus photography and fundus autofluorescence with the California ultra-widefield retinal imaging system (Optos, Dunfermline, UK), spectral-domain optical coherence tomography (SD-OCT) (Heidelberg Spectralis HRA + OCT; Heidelberg Engineering, Heidelberg, Germany), and en face OCT angiography (OCTA) (AngioPlex, Cirrus HD-OCT 5000; Carl Zeiss Meditec, Dublin, CA). The patient presented with a visual acuity of counting fingers in the right eye and 20/32 in the left eye. Fundus examination and SD-OCT showed typical PPRCA alterations in both eyes and a macular coloboma in the right eye. The OCTA showed relative sparing of the retinal capillary plexuses, with diffuse defects in the choriocapillaris. The authors concluded OCTA imaging of PPRCA suggests more insights of the pathogenesis of this disease, showing that the disease primarily affects the choroidal vascular network, with a relative sparing of the retinal vasculature. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:381-383.]. Copyright 2018, SLACK Incorporated.

Automatic detection of blood vessels in retinal images for diabetic retinopathy diagnosis.

PubMed

Raja, D Siva Sundhara; Vasuki, S

2015-01-01

Diabetic retinopathy (DR) is a leading cause of vision loss in diabetic patients. DR is mainly caused due to the damage of retinal blood vessels in the diabetic patients. It is essential to detect and segment the retinal blood vessels for DR detection and diagnosis, which prevents earlier vision loss in diabetic patients. The computer aided automatic detection and segmentation of blood vessels through the elimination of optic disc (OD) region in retina are proposed in this paper. The OD region is segmented using anisotropic diffusion filter and subsequentially the retinal blood vessels are detected using mathematical binary morphological operations. The proposed methodology is tested on two different publicly available datasets and achieved 93.99% sensitivity, 98.37% specificity, 98.08% accuracy in DRIVE dataset and 93.6% sensitivity, 98.96% specificity, and 95.94% accuracy in STARE dataset, respectively.

Vessel Segmentation in Retinal Images Using Multi-scale Line Operator and K-Means Clustering.

PubMed

Saffarzadeh, Vahid Mohammadi; Osareh, Alireza; Shadgar, Bita

2014-04-01

Detecting blood vessels is a vital task in retinal image analysis. The task is more challenging with the presence of bright and dark lesions in retinal images. Here, a method is proposed to detect vessels in both normal and abnormal retinal fundus images based on their linear features. First, the negative impact of bright lesions is reduced by using K-means segmentation in a perceptive space. Then, a multi-scale line operator is utilized to detect vessels while ignoring some of the dark lesions, which have intensity structures different from the line-shaped vessels in the retina. The proposed algorithm is tested on two publicly available STARE and DRIVE databases. The performance of the method is measured by calculating the area under the receiver operating characteristic curve and the segmentation accuracy. The proposed method achieves 0.9483 and 0.9387 localization accuracy against STARE and DRIVE respectively.

A consonant construction of the hyaloid and retinal vascular systems by the angiogenic process.

PubMed

Gergely, K; Gerinec, A

2011-01-01

There has been much debate as to whether the retinal vasculature forms by angiogenesis or vasculogenesis, thus angiogenesis is now accepted. We suppose that signals necessary for proper localization and development of the hyaloid and retinal vascular systems are already in place prior to the time at which these systems are developed. The remarkable conservation of vascular patterning suggests that specific genetic programs coordinate its formation. Evidence for a genetic program comes particularly from the characterization of gene-targeted mice and mutational analysis in zebrafish, but the exact genetic pathways remain poorly defined. Considering all the things from the aspect of angiogenesis significant differences exist between the mentioned vascular systems only in their lifetime (a) and location (b): (a) The hyaloid vasculature is a complex of transient intraocular vessels, while the retinal vessels are adapted for the whole life. (b) The hyaloid system fills the interior of the optic cup and this way "occupies" three-dimensional space while the distribution of the retinal vessels is relatively planar (two-dimensional) in the retina. We assume that retinal vessels are "built" in the same manner as the hyaloid vasculature and the outcomes at the embryological, histological, cellular and molecular levels confirm it. We show a consonant construction of both systems. The human organism does not have any rational reason to build up one system (i.e. the hyaloid vasculature) by angiogenesis and practically the same system (i.e. the retinal vessels) by another, de novo process, in the eye. It would be a waste of energy and various essential molecules. Thus, it seems that the retinal vascular system is an advanced copy of the hyaloid vessels (Tab. 1, Ref. 143).

Vasoconstriction and Impairment of Neurovascular Coupling after Subarachnoid Hemorrhage: a Descriptive Analysis of Retinal Changes.

PubMed

Conzen, Catharina; Albanna, Walid; Weiss, Miriam; Kürten, David; Vilser, Walthard; Kotliar, Konstantin; Zäske, Charlotte; Clusmann, Hans; Schubert, Gerrit Alexander

2018-06-01

Impaired cerebral autoregulation and neurovascular coupling (NVC) contribute to delayed cerebral ischemia after subarachnoid hemorrhage (SAH). Retinal vessel analysis (RVA) allows non-invasive assessment of vessel dimension and NVC hereby demonstrating a predictive value in the context of various neurovascular diseases. Using RVA as a translational approach, we aimed to assess the retinal vessels in patients with SAH. RVA was performed prospectively in 24 patients with acute SAH (group A: day 5-14), in 11 patients 3 months after ictus (group B: day 90 ± 35), and in 35 age-matched healthy controls (group C). Data was acquired using a Retinal Vessel Analyzer (Imedos Systems UG, Jena) for examination of retinal vessel dimension and NVC using flicker-light excitation. Diameter of retinal vessels-central retinal arteriolar and venular equivalent-was significantly reduced in the acute phase (p < 0.001) with gradual improvement in group B (p < 0.05). Arterial NVC of group A was significantly impaired with diminished dilatation (p < 0.001) and reduced area under the curve (p < 0.01) when compared to group C. Group B showed persistent prolonged latency of arterial dilation (p < 0.05). Venous NVC was significantly delayed after SAH compared to group C (A p < 0.001; B p < 0.05). To our knowledge, this is the first clinical study to document retinal vasoconstriction and impairment of NVC in patients with SAH. Using non-invasive RVA as a translational approach, characteristic patterns of compromise were detected for the arterial and venous compartment of the neurovascular unit in a time-dependent fashion. Recruitment will continue to facilitate a correlation analysis with clinical course and outcome.

Optical coherence tomography angiography indicates associations of the retinal vascular network and disease activity in multiple sclerosis.

PubMed

Feucht, Nikolaus; Maier, Mathias; Lepennetier, Gildas; Pettenkofer, Moritz; Wetzlmair, Carmen; Daltrozzo, Tanja; Scherm, Pauline; Zimmer, Claus; Hoshi, Muna-Miriam; Hemmer, Bernhard; Korn, Thomas; Knier, Benjamin

2018-01-01

Patients with multiple sclerosis (MS) and clinically isolated syndrome (CIS) may show alterations of retinal layer architecture as measured by optical coherence tomography. Little is known about changes in the retinal vascular network during MS. To characterize retinal vessel structures in patients with MS and CIS and to test for associations with MS disease activity. In all, 42 patients with MS or CIS and 50 healthy controls underwent retinal optical coherence tomography angiography (OCT-A) with analysis of the superficial and deep vascular plexuses and the choriocapillaries. We tested OCT-A parameters for associations with retinal layer volumes, history of optic neuritis (ON), and the retrospective disease activity. Inner retinal layer volumes correlated positively with the density of both the superficial and deep vascular plexuses. Eyes of MS/CIS patients with a history of ON revealed reduced vessel densities of the superficial and deep vascular plexuses as compared to healthy controls. Higher choriocapillary vessel densities were associated with ongoing inflammatory disease activity during 24 months prior to OCT-A examination in MS and CIS patients. Optic neuritis is associated with rarefaction of the superficial and deep retinal vessels. Alterations of the choriocapillaries might be linked to disease activity in MS.

Endothelial SRF/MRTF ablation causes vascular disease phenotypes in murine retinae

PubMed Central

Weinl, Christine; Riehle, Heidemarie; Park, Dongjeong; Stritt, Christine; Beck, Susanne; Huber, Gesine; Wolburg, Hartwig; Olson, Eric N.; Seeliger, Mathias W.; Adams, Ralf H.; Nordheim, Alfred

2013-01-01

Retinal vessel homeostasis ensures normal ocular functions. Consequently, retinal hypovascularization and neovascularization, causing a lack and an excess of vessels, respectively, are hallmarks of human retinal pathology. We provide evidence that EC-specific genetic ablation of either the transcription factor SRF or its cofactors MRTF-A and MRTF-B, but not the SRF cofactors ELK1 or ELK4, cause retinal hypovascularization in the postnatal mouse eye. Inducible, EC-specific deficiency of SRF or MRTF-A/MRTF-B during postnatal angiogenesis impaired endothelial tip cell filopodia protrusion, resulting in incomplete formation of the retinal primary vascular plexus, absence of the deep plexi, and persistence of hyaloid vessels. All of these features are typical of human hypovascularization-related vitreoretinopathies, such as familial exudative vitreoretinopathies including Norrie disease. In contrast, conditional EC deletion of Srf in adult murine vessels elicited intraretinal neovascularization that was reminiscent of the age-related human pathologies retinal angiomatous proliferation and macular telangiectasia. These results indicate that angiogenic homeostasis is ensured by differential stage-specific functions of SRF target gene products in the developing versus the mature retinal vasculature and suggest that the actin-directed MRTF-SRF signaling axis could serve as a therapeutic target in the treatment of human vascular retinal diseases. PMID:23563308

Endothelial SRF/MRTF ablation causes vascular disease phenotypes in murine retinae.

PubMed

Weinl, Christine; Riehle, Heidemarie; Park, Dongjeong; Stritt, Christine; Beck, Susanne; Huber, Gesine; Wolburg, Hartwig; Olson, Eric N; Seeliger, Mathias W; Adams, Ralf H; Nordheim, Alfred

2013-05-01

Retinal vessel homeostasis ensures normal ocular functions. Consequently, retinal hypovascularization and neovascularization, causing a lack and an excess of vessels, respectively, are hallmarks of human retinal pathology. We provide evidence that EC-specific genetic ablation of either the transcription factor SRF or its cofactors MRTF-A and MRTF-B, but not the SRF cofactors ELK1 or ELK4, cause retinal hypovascularization in the postnatal mouse eye. Inducible, EC-specific deficiency of SRF or MRTF-A/MRTF-B during postnatal angiogenesis impaired endothelial tip cell filopodia protrusion, resulting in incomplete formation of the retinal primary vascular plexus, absence of the deep plexi, and persistence of hyaloid vessels. All of these features are typical of human hypovascularization-related vitreoretinopathies, such as familial exudative vitreoretinopathies including Norrie disease. In contrast, conditional EC deletion of Srf in adult murine vessels elicited intraretinal neovascularization that was reminiscent of the age-related human pathologies retinal angiomatous proliferation and macular telangiectasia. These results indicate that angiogenic homeostasis is ensured by differential stage-specific functions of SRF target gene products in the developing versus the mature retinal vasculature and suggest that the actin-directed MRTF-SRF signaling axis could serve as a therapeutic target in the treatment of human vascular retinal diseases.

Fpga based hardware synthesis for automatic segmentation of retinal blood vessels in diabetic retinopathy images.

PubMed

Sivakamasundari, J; Kavitha, G; Sujatha, C M; Ramakrishnan, S

2014-01-01

Diabetic Retinopathy (DR) is a disorder that affects the structure of retinal blood vessels due to long-standing diabetes mellitus. Real-Time mass screening system for DR is vital for timely diagnosis and periodic screening to prevent the patient from severe visual loss. Human retinal fundus images are widely used for an automated segmentation of blood vessel and diagnosis of various blood vessel disorders. In this work, an attempt has been made to perform hardware synthesis of Kirsch template based edge detection for segmentation of blood vessels. This method is implemented using LabVIEW software and is synthesized in field programmable gate array board to yield results in real-time application. The segmentation of blood vessels using Kirsch based edge detection is compared with other edge detection methods such as Sobel, Prewitt and Canny. The texture features such as energy, entropy, contrast, mean, homogeneity and structural feature namely ratio of vessel to vessel free area are obtained from the segmented images. The performance of segmentation is analysed in terms of sensitivity, specificity and accuracy. It is observed from the results that the Kirsch based edge detection technique segmented the edges of blood vessels better than other edge detection techniques. The ratio of vessel to vessel free area classified the normal and DR affected retinal images more significantly than other texture based features. FPGA based hardware synthesis of Kirsch edge detection method is able to differentiate normal and diseased images with high specificity (93%). This automated segmentation of retinal blood vessels system could be used in computer-assisted diagnosis for diabetic retinopathy screening in real-time application.

An automated retinal imaging method for the early diagnosis of diabetic retinopathy.

PubMed

Franklin, S Wilfred; Rajan, S Edward

2013-01-01

Diabetic retinopathy is a microvascular complication of long-term diabetes and is the major cause for eyesight loss due to changes in blood vessels of the retina. Major vision loss due to diabetic retinopathy is highly preventable with regular screening and timely intervention at the earlier stages. Retinal blood vessel segmentation methods help to identify the successive stages of such sight threatening diseases like diabetes. To develop and test a novel retinal imaging method which segments the blood vessels automatically from retinal images, which helps the ophthalmologists in the diagnosis and follow-up of diabetic retinopathy. This method segments each image pixel as vessel or nonvessel, which in turn, used for automatic recognition of the vasculature in retinal images. Retinal blood vessels were identified by means of a multilayer perceptron neural network, for which the inputs were derived from the Gabor and moment invariants-based features. Back propagation algorithm, which provides an efficient technique to change the weights in a feed forward network, is utilized in our method. Quantitative results of sensitivity, specificity and predictive values were obtained in our method and the measured accuracy of our segmentation algorithm was 95.3%, which is better than that presented by state-of-the-art approaches. The evaluation procedure used and the demonstrated effectiveness of our automated retinal imaging method proves itself as the most powerful tool to diagnose diabetic retinopathy in the earlier stages.

Retinal vessel diameters and reactivity in diabetes mellitus and/or cardiovascular disease.

PubMed

Heitmar, R; Lip, G Y H; Ryder, R E; Blann, A D

2017-04-26

Retinal vessel calibre and vascular dilation/constriction in response to flicker light provocation may provide a measure distinguishing patients suffering from diabetes mellitus and/or cardiovascular disease. One hundred and sixteen age and sex matched patients with diabetes mellitus (DM), cardiovascular disease (CVD) and both DM and CVD (DM + CVD) underwent systemic and intraocular pressure measurements. Retinal vessel calibres were assessed using a validated computer-based program to compute central retinal artery and vein equivalents (CRVE) from monochromatic retinal images. Vessel dilation and constriction responses to flicker light provocation were assessed by continuous retinal vessel diameter recordings. Plasma endothelial markers von Willebrand factor (vWf) and soluble E selectin (sEsel) were measured by ELISA. Retinal vessel calibres were comparable across groups but CRVE correlated significantly with disease duration in DM patients (r = 0.57, p < 0.001). Patients suffering DM only exhibited reduced arterial vasomotion at rest and reduced arterial constriction following flicker light induced vessel dilation compared to patients with CVD and those suffering both CVD + DM (p = 0.030). Patients suffering from CVD + DM exhibited significant differences between each flicker cycle in regards to arterial maximum constriction (p = 0.006) and time needed to reach arterial maximum dilation (p = 0.004), whereas the other two groups did not show such inconsistencies between individual flicker cycles. vWf was raised in CVD + DM compared to the other two groups (p ≤ 0.02), whilst sEsel was raised in CVD + DM compared to DM alone (p = 0.044). Dynamic retinal vascular calibres as obtained by continuous diameter measurements using flicker light provocation can reveal subtle differences between groups suffering from CVD with and without DM. This difference in reaction pattern and lack of arterial constriction in DM may provide a suitable marker to monitor progression.

Blood Vessel Extraction in Color Retinal Fundus Images with Enhancement Filtering and Unsupervised Classification

PubMed Central

2017-01-01

Retinal blood vessels have a significant role in the diagnosis and treatment of various retinal diseases such as diabetic retinopathy, glaucoma, arteriosclerosis, and hypertension. For this reason, retinal vasculature extraction is important in order to help specialists for the diagnosis and treatment of systematic diseases. In this paper, a novel approach is developed to extract retinal blood vessel network. Our method comprises four stages: (1) preprocessing stage in order to prepare dataset for segmentation; (2) an enhancement procedure including Gabor, Frangi, and Gauss filters obtained separately before a top-hat transform; (3) a hard and soft clustering stage which includes K-means and Fuzzy C-means (FCM) in order to get binary vessel map; and (4) a postprocessing step which removes falsely segmented isolated regions. The method is tested on color retinal images obtained from STARE and DRIVE databases which are available online. As a result, Gabor filter followed by K-means clustering method achieves 95.94% and 95.71% of accuracy for STARE and DRIVE databases, respectively, which are acceptable for diagnosis systems. PMID:29065611

Measurement of retinal blood flow in the rat by combining Doppler Fourier-domain optical coherence tomography with fundus imaging

NASA Astrophysics Data System (ADS)

Werkmeister, René M.; Vietauer, Martin; Knopf, Corinna; Fürnsinn, Clemens; Leitgeb, Rainer A.; Reitsamer, Herbert; Gröschl, Martin; Garhöfer, Gerhard; Vilser, Walthard; Schmetterer, Leopold

2014-10-01

A wide variety of ocular diseases are associated with abnormalities in ocular circulation. As such, there is considerable interest in techniques for quantifying retinal blood flow, among which Doppler optical coherence tomography (OCT) may be the most promising. We present an approach to measure retinal blood flow in the rat using a new optical system that combines the measurement of blood flow velocities via Doppler Fourier-domain optical coherence tomography and the measurement of vessel diameters using a fundus camera-based technique. Relying on fundus images for extraction of retinal vessel diameters instead of OCT images improves the reliability of the technique. The system was operated with an 841-nm superluminescent diode and a charge-coupled device camera that could be operated at a line rate of 20 kHz. We show that the system is capable of quantifying the response of 100% oxygen breathing on the retinal blood flow. In six rats, we observed a decrease in retinal vessel diameters of 13.2% and a decrease in retinal blood velocity of 42.6%, leading to a decrease in retinal blood flow of 56.7%. Furthermore, in four rats, the response of retinal blood flow during stimulation with diffuse flicker light was assessed. Retinal vessel diameter and blood velocity increased by 3.4% and 28.1%, respectively, leading to a relative increase in blood flow of 36.2%;. The presented technique shows much promise to quantify early changes in retinal blood flow during provocation with various stimuli in rodent models of ocular diseases in rats.

Does Physical Fitness Buffer the Relationship between Psychosocial Stress, Retinal Vessel Diameters, and Blood Pressure among Primary Schoolchildren?

PubMed Central

Endes, Katharina; Herrmann, Christian; Colledge, Flora; Brand, Serge; Donath, Lars; Faude, Oliver; Pühse, Uwe; Hanssen, Henner; Zahner, Lukas

2016-01-01

Background. Strong evidence exists showing that psychosocial stress plays an important part in the development of cardiovascular diseases. Because physical inactivity is associated with less favourable retinal vessel diameter and blood pressure profiles, this study explores whether physical fitness is able to buffer the negative effects of psychosocial stress on retinal vessel diameters and blood pressure in young children. Methods. 325 primary schoolchildren (51% girls, Mage = 7.28 years) took part in this cross-sectional research project. Retinal arteriolar diameters, retinal venular diameters, arteriolar to venular ratio, and systolic and diastolic blood pressure were assessed in all children. Interactions terms between physical fitness (performance in the 20 m shuttle run test) and four indicators of psychosocial stress (parental reports of critical life events, family, peer and school stress) were tested in a series of hierarchical regression analyses. Results. Critical life events and family, peer, and school-related stress were only weakly associated with retinal vessel diameters and blood pressure. No support was found for a stress-buffering effect of physical fitness. Conclusion. More research is needed with different age groups to find out if and from what age physical fitness can protect against arteriolar vessel narrowing and the occurrence of other cardiovascular disease risk factors. PMID:27795958

Roi Detection and Vessel Segmentation in Retinal Image

NASA Astrophysics Data System (ADS)

Sabaz, F.; Atila, U.

2017-11-01

Diabetes disrupts work by affecting the structure of the eye and afterwards leads to loss of vision. Depending on the stage of disease that called diabetic retinopathy, there are sudden loss of vision and blurred vision problems. Automated detection of vessels in retinal images is a useful study to diagnose eye diseases, disease classification and other clinical trials. The shape and structure of the vessels give information about the severity of the disease and the stage of the disease. Automatic and fast detection of vessels allows for a quick diagnosis of the disease and the treatment process to start shortly. ROI detection and vessel extraction methods for retinal image are mentioned in this study. It is shown that the Frangi filter used in image processing can be successfully used in detection and extraction of vessels.

Norrie gene product is necessary for regression of hyaloid vessels.

PubMed

Ohlmann, Anne V; Adamek, Edith; Ohlmann, Andreas; Lütjen-Drecoll, Elke

2004-07-01

To investigate the nature and origin of the vitreous membranes in mice with knock-out of the Norrie gene product (ND mice). Eighty-two eyes of ND mice of different age groups (postnatal day [P]0-13 months) and 95 age-matched wild-type control mice were investigated. In vitreoretinal wholemounts and in sagittal sections, vessels and free cells were visualized by labeling for lectin. In addition, staining with a marker for macrophages (F4/80) and collagen XVIII/endostatin known to be involved in regression of hyaloid vessels was performed for light and electron microscopic investigations. Endostatin expression was confirmed by Western blot analysis. Wild-type controls showed the typical pattern of hyaloid vessels, their regression and concomitantly retinal vasculogenesis and angiogenesis. Hyaloid vessels all stained for endostatin, whereas retinal vessels remained unstained. In ND mice, 1 to 5 days after birth, the hyaloid and retinal vasculatures were comparable to that in control mice. The hyaloid vessels also stained for endostatin. Numerous F4/80-positive cells were present adjacent to the vessels. With increasing age, only a few connecting branches of the hyaloid vessels regressed. Even in old mice most of the hyaloid vessels persisted. The vessels still stained for endostatin. Retinal angiogenesis was impaired. Retrolental membranes in ND mice consist of persistent hyaloid vessels, indicating that the ND gene product is important for the process of regression of these vessels. The ND gene product neither influences endostatin expression nor the presence of macrophages.

An approach to localize the retinal blood vessels using bit planes and centerline detection.

PubMed

Fraz, M M; Barman, S A; Remagnino, P; Hoppe, A; Basit, A; Uyyanonvara, B; Rudnicka, A R; Owen, C G

2012-11-01

The change in morphology, diameter, branching pattern or tortuosity of retinal blood vessels is an important indicator of various clinical disorders of the eye and the body. This paper reports an automated method for segmentation of blood vessels in retinal images. A unique combination of techniques for vessel centerlines detection and morphological bit plane slicing is presented to extract the blood vessel tree from the retinal images. The centerlines are extracted by using the first order derivative of a Gaussian filter in four orientations and then evaluation of derivative signs and average derivative values is performed. Mathematical morphology has emerged as a proficient technique for quantifying the blood vessels in the retina. The shape and orientation map of blood vessels is obtained by applying a multidirectional morphological top-hat operator with a linear structuring element followed by bit plane slicing of the vessel enhanced grayscale image. The centerlines are combined with these maps to obtain the segmented vessel tree. The methodology is tested on three publicly available databases DRIVE, STARE and MESSIDOR. The results demonstrate that the performance of the proposed algorithm is comparable with state of the art techniques in terms of accuracy, sensitivity and specificity. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Handheld four-wavelength retinal vessel oximeter

NASA Astrophysics Data System (ADS)

Heaton, Larry C.; Smith, Matthew H.; Denninghoff, Kurt R.; Hillman, Lloyd W.

2000-06-01

Several techniques for measuring the oxygen saturation of blood in retinal vessels have been reported. One interesting application of retinal vessel oximetry is the identification of occult blood loss in trauma victims. However, all the devices described to date are too bulky and cumbersome to be used in a trauma bay or in the field. We present a design for a handheld instrument that performs four-wavelength retinal vessel oximetry. This device is comparable in size and weight to a commercially available camcorder, and is suitable for use in the trauma bay. The compact size of this device could also extend its applications beyond traditional clinical settings, as it could be used by primary care physicians and home health care workers for the screening and monitoring of ophthalmic diseases. Principles of operation and preliminary data from the device will be described.

Pharmacologic Activation of Wnt Signaling by Lithium Normalizes Retinal Vasculature in a Murine Model of Familial Exudative Vitreoretinopathy.

PubMed

Wang, Zhongxiao; Liu, Chi-Hsiu; Sun, Ye; Gong, Yan; Favazza, Tara L; Morss, Peyton C; Saba, Nicholas J; Fredrick, Thomas W; He, Xi; Akula, James D; Chen, Jing

2016-10-01

Familial exudative vitreoretinopathy (FEVR) is characterized by delayed retinal vascular development, which promotes hypoxia-induced pathologic vessels. In severe cases FEVR may lead to retinal detachment and visual impairment. Genetic studies linked FEVR with mutations in Wnt signaling ligand or receptors, including low-density lipoprotein receptor-related protein 5 (LRP5) gene. Here, we investigated ocular pathologies in a Lrp5 knockout (Lrp5(-/-)) mouse model of FEVR and explored whether treatment with a pharmacologic Wnt activator lithium could bypass the genetic defects, thereby protecting against eye pathologies. Lrp5(-/-) mice displayed significantly delayed retinal vascular development, absence of deep layer retinal vessels, leading to increased levels of vascular endothelial growth factor and subsequent pathologic glomeruloid vessels, as well as decreased inner retinal visual function. Lithium treatment in Lrp5(-/-) mice significantly restored the delayed development of retinal vasculature and the intralaminar capillary networks, suppressed formation of pathologic glomeruloid structures, and promoted hyaloid vessel regression. Moreover, lithium treatment partially rescued inner-retinal visual function and increased retinal thickness. These protective effects of lithium were largely mediated through restoration of canonical Wnt signaling in Lrp5(-/-) retina. Lithium treatment also substantially increased vascular tubular formation in LRP5-deficient endothelial cells. These findings suggest that pharmacologic activation of Wnt signaling may help treat ocular pathologies in FEVR and potentially other defective Wnt signaling-related diseases. Copyright © 2016 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

Retinal health information and notification system (RHINO)

NASA Astrophysics Data System (ADS)

Dashtbozorg, Behdad; Zhang, Jiong; Abbasi-Sureshjani, Samaneh; Huang, Fan; ter Haar Romeny, Bart M.

2017-03-01

The retinal vasculature is the only part of the blood circulation system that can be observed non-invasively using fundus cameras. Changes in the dynamic properties of retinal blood vessels are associated with many systemic and vascular diseases, such as hypertension, coronary heart disease and diabetes. The assessment of the characteristics of the retinal vascular network provides important information for an early diagnosis and prognosis of many systemic and vascular diseases. The manual analysis of the retinal vessels and measurement of quantitative biomarkers in large-scale screening programs is a tedious task, time-consuming and costly. This paper describes a reliable, automated, and efficient retinal health information and notification system (acronym RHINO) which can extract a wealth of geometric biomarkers in large volumes of fundus images. The fully automated software presented in this paper includes vessel enhancement and segmentation, artery/vein classification, optic disc, fovea, and vessel junction detection, and bifurcation/crossing discrimination. Pipelining these tools allows the assessment of several quantitative vascular biomarkers: width, curvature, bifurcation geometry features and fractal dimension. The brain-inspired algorithms outperform most of the state-of-the-art techniques. Moreover, several annotation tools are implemented in RHINO for the manual labeling of arteries and veins, marking optic disc and fovea, and delineating vessel centerlines. The validation phase is ongoing and the software is currently being used for the analysis of retinal images from the Maastricht study (the Netherlands) which includes over 10,000 subjects (healthy and diabetic) with a broad spectrum of clinical measurements

Can partial coherence interferometry be used to determine retinal shape?

PubMed

Atchison, David A; Charman, W Neil

2011-05-01

To determine likely errors in estimating retinal shape using partial coherence interferometric instruments when no allowance is made for optical distortion. Errors were estimated using Gullstrand no. 1 schematic eye and variants which included a 10 diopter (D) axial myopic eye, an emmetropic eye with a gradient-index lens, and a 10.9 D accommodating eye with a gradient-index lens. Performance was simulated for two commercial instruments, the IOLMaster (Carl Zeiss Meditec) and the Lenstar LS 900 (Haag-Streit AG). The incident beam was directed toward either the center of curvature of the anterior cornea (corneal-direction method) or the center of the entrance pupil (pupil-direction method). Simple trigonometry was used with the corneal intercept and the incident beam angle to estimate retinal contour. Conics were fitted to the estimated contours. The pupil-direction method gave estimates of retinal contour that were much too flat. The cornea-direction method gave similar results for IOLMaster and Lenstar approaches. The steepness of the retinal contour was slightly overestimated, the exact effects varying with the refractive error, gradient index, and accommodation. These theoretical results suggest that, for field angles ≤30°, partial coherence interferometric instruments are of use in estimating retinal shape by the corneal-direction method with the assumptions of a regular retinal shape and no optical distortion. It may be possible to improve on these estimates out to larger field angles by using optical modeling to correct for distortion.

Feature-Based Retinal Image Registration Using D-Saddle Feature

PubMed Central

Hasikin, Khairunnisa; A. Karim, Noor Khairiah; Ahmedy, Fatimah

2017-01-01

Retinal image registration is important to assist diagnosis and monitor retinal diseases, such as diabetic retinopathy and glaucoma. However, registering retinal images for various registration applications requires the detection and distribution of feature points on the low-quality region that consists of vessels of varying contrast and sizes. A recent feature detector known as Saddle detects feature points on vessels that are poorly distributed and densely positioned on strong contrast vessels. Therefore, we propose a multiresolution difference of Gaussian pyramid with Saddle detector (D-Saddle) to detect feature points on the low-quality region that consists of vessels with varying contrast and sizes. D-Saddle is tested on Fundus Image Registration (FIRE) Dataset that consists of 134 retinal image pairs. Experimental results show that D-Saddle successfully registered 43% of retinal image pairs with average registration accuracy of 2.329 pixels while a lower success rate is observed in other four state-of-the-art retinal image registration methods GDB-ICP (28%), Harris-PIIFD (4%), H-M (16%), and Saddle (16%). Furthermore, the registration accuracy of D-Saddle has the weakest correlation (Spearman) with the intensity uniformity metric among all methods. Finally, the paired t-test shows that D-Saddle significantly improved the overall registration accuracy of the original Saddle. PMID:29204257

Novel non-contact retina camera for the rat and its application to dynamic retinal vessel analysis

PubMed Central

Link, Dietmar; Strohmaier, Clemens; Seifert, Bernd U.; Riemer, Thomas; Reitsamer, Herbert A.; Haueisen, Jens; Vilser, Walthard

2011-01-01

We present a novel non-invasive and non-contact system for reflex-free retinal imaging and dynamic retinal vessel analysis in the rat. Theoretical analysis was performed prior to development of the new optical design, taking into account the optical properties of the rat eye and its specific illumination and imaging requirements. A novel optical model of the rat eye was developed for use with standard optical design software, facilitating both sequential and non-sequential modes. A retinal camera for the rat was constructed using standard optical and mechanical components. The addition of a customized illumination unit and existing standard software enabled dynamic vessel analysis. Seven-minute in-vivo vessel diameter recordings performed on 9 Brown-Norway rats showed stable readings. On average, the coefficient of variation was (1.1 ± 0.19) % for the arteries and (0.6 ± 0.08) % for the veins. The slope of the linear regression analysis was (0.56 ± 0.26) % for the arteries and (0.15 ± 0.27) % for the veins. In conclusion, the device can be used in basic studies of retinal vessel behavior. PMID:22076270

Bim is Responsible for the Inherent Sensitivity of the Developing Retinal Vasculature to Hyperoxia

PubMed Central

Wang, Shoujian; Park, SunYoung; Fei, Ping; Sorenson, Christine M.

2010-01-01

Apoptosis plays an important role in development and remodeling of vasculature during organogenesis. Coordinated branching and remodeling of the retinal vascular tree is essential for normal retinal function. Bcl-2 family members, such as bim can not only influence apoptosis, but also cell adhesive and migratory properties essential during vascular development. Here we examined the impact of bim deficiency on postnatal retinal vascularization, as well as retinal neovascularization during oxygen-induced ischemic retinopathy (OIR) and laser-induced choroidal neovascularization. Loss of bim expression was associated with increased retinal vascular density in mature animals. This was mainly attributed to increased numbers of pericytes and endothelial cells. However, the initial spread of the superficial layer of retinal vasculature and, the appearance and density of the tip cells were similar in bim +/+ and bim -/- mice. In addition, hyaloid vessel regression was attenuated in the absence of bim. Furthermore, in the absence of bim retinal vessel obliteration and neovascularization did not occur during OIR. Instead, normal inner retinal vascularization proceeded independent of changes in oxygen levels. In contrast, choroidal neovascularization occurred equally well in bim +/+ and bim -/- mice. Together our data suggest bim expression may be responsible for the inherent sensitivity of the developing retinal vasculature to changes in oxygen levels, and promotes vessel obliteration in response to hyperoxia. PMID:21047504

Expression and activation of STAT3 in ischemia-induced retinopathy.

PubMed

Mechoulam, Hadas; Pierce, Eric A

2005-12-01

Signal transducer and activator of transcription protein-3 (STAT3) is a transcription factor that participates in many biological processes, including tumor angiogenesis. The expression and activation of Stat3 in the mouse model of ischemia-induced retinal neovascularization was investigated to evaluate the possible role of STAT3 in retinal vascular disease. Retinal neovascularization was induced in mice pups by exposure to hyperoxia. Gene microarrays were used to identify genes whose expression in the retina is altered at postnatal day (P)12 and P18. The relative levels of Stat3 mRNA were determined by semiquantitative RT-PCR. Stat3 protein levels and the levels of the activated form of Stat3 (pStat3) at P12, P15, P18, and P22 were determined by immunoblot analysis. Stat3 and pStat3 were demonstrated by immunofluorescence in retinal sections at P12, P15, and P18. In a series of microarray experiments, increased Stat3 mRNA levels in the retina were detected at P18. This result was validated by RT-PCR and demonstrated that Stat3 and pStat3 protein levels also increase during the development of neovascularization. Stat3 partially colocalized with blood vessels at the peak of neovascularization. pStat3 colocalized completely with blood vessels in both experimental samples and age-matched controls. pStat3 staining increased notably in the neovascular vessels at P15 and P18 and was more strongly associated with the epiretinal vessels than with inner retinal vessels. It was not detected in larger blood vessels, such as those of the optic nerve. The level of Stat3 expression increased, and pStat3 was observed in association with retinal neovascularization. Activated Stat3 was preferentially localized to neovascular retinal vessels. These data suggest that STAT3 may have a role in proliferative retinopathy.

Automated construction of arterial and venous trees in retinal images.

PubMed

Hu, Qiao; Abràmoff, Michael D; Garvin, Mona K

2015-10-01

While many approaches exist to segment retinal vessels in fundus photographs, only a limited number focus on the construction and disambiguation of arterial and venous trees. Previous approaches are local and/or greedy in nature, making them susceptible to errors or limiting their applicability to large vessels. We propose a more global framework to generate arteriovenous trees in retinal images, given a vessel segmentation. In particular, our approach consists of three stages. The first stage is to generate an overconnected vessel network, named the vessel potential connectivity map (VPCM), consisting of vessel segments and the potential connectivity between them. The second stage is to disambiguate the VPCM into multiple anatomical trees, using a graph-based metaheuristic algorithm. The third stage is to classify these trees into arterial or venous (A/V) trees. We evaluated our approach with a ground truth built based on a public database, showing a pixel-wise classification accuracy of 88.15% using a manual vessel segmentation as input, and 86.11% using an automatic vessel segmentation as input.

Automated detection and classification of major retinal vessels for determination of diameter ratio of arteries and veins

NASA Astrophysics Data System (ADS)

Muramatsu, Chisako; Hatanaka, Yuji; Iwase, Tatsuhiko; Hara, Takeshi; Fujita, Hiroshi

2010-03-01

Abnormalities of retinal vasculatures can indicate health conditions in the body, such as the high blood pressure and diabetes. Providing automatically determined width ratio of arteries and veins (A/V ratio) on retinal fundus images may help physicians in the diagnosis of hypertensive retinopathy, which may cause blindness. The purpose of this study was to detect major retinal vessels and classify them into arteries and veins for the determination of A/V ratio. Images used in this study were obtained from DRIVE database, which consists of 20 cases each for training and testing vessel detection algorithms. Starting with the reference standard of vasculature segmentation provided in the database, major arteries and veins each in the upper and lower temporal regions were manually selected for establishing the gold standard. We applied the black top-hat transformation and double-ring filter to detect retinal blood vessels. From the extracted vessels, large vessels extending from the optic disc to temporal regions were selected as target vessels for calculation of A/V ratio. Image features were extracted from the vessel segments from quarter-disc to one disc diameter from the edge of optic discs. The target segments in the training cases were classified into arteries and veins by using the linear discriminant analysis, and the selected parameters were applied to those in the test cases. Out of 40 pairs, 30 pairs (75%) of arteries and veins in the 20 test cases were correctly classified. The result can be used for the automated calculation of A/V ratio.

Supervised retinal vessel segmentation from color fundus images based on matched filtering and AdaBoost classifier.

PubMed

Memari, Nogol; Ramli, Abd Rahman; Bin Saripan, M Iqbal; Mashohor, Syamsiah; Moghbel, Mehrdad

2017-01-01

The structure and appearance of the blood vessel network in retinal fundus images is an essential part of diagnosing various problems associated with the eyes, such as diabetes and hypertension. In this paper, an automatic retinal vessel segmentation method utilizing matched filter techniques coupled with an AdaBoost classifier is proposed. The fundus image is enhanced using morphological operations, the contrast is increased using contrast limited adaptive histogram equalization (CLAHE) method and the inhomogeneity is corrected using Retinex approach. Then, the blood vessels are enhanced using a combination of B-COSFIRE and Frangi matched filters. From this preprocessed image, different statistical features are computed on a pixel-wise basis and used in an AdaBoost classifier to extract the blood vessel network inside the image. Finally, the segmented images are postprocessed to remove the misclassified pixels and regions. The proposed method was validated using publicly accessible Digital Retinal Images for Vessel Extraction (DRIVE), Structured Analysis of the Retina (STARE) and Child Heart and Health Study in England (CHASE_DB1) datasets commonly used for determining the accuracy of retinal vessel segmentation methods. The accuracy of the proposed segmentation method was comparable to other state of the art methods while being very close to the manual segmentation provided by the second human observer with an average accuracy of 0.972, 0.951 and 0.948 in DRIVE, STARE and CHASE_DB1 datasets, respectively.

Plastic roles of pericytes in the blood-retinal barrier.

PubMed

Park, Do Young; Lee, Junyeop; Kim, Jaeryung; Kim, Kangsan; Hong, Seonpyo; Han, Sangyeul; Kubota, Yoshiaki; Augustin, Hellmut G; Ding, Lei; Kim, Jin Woo; Kim, Hail; He, Yulong; Adams, Ralf H; Koh, Gou Young

2017-05-16

The blood-retinal barrier (BRB) consists of tightly interconnected capillary endothelial cells covered with pericytes and glia, but the role of the pericytes in BRB regulation is not fully understood. Here, we show that platelet-derived growth factor (PDGF)-B/PDGF receptor beta (PDGFRβ) signalling is critical in formation and maturation of BRB through active recruitment of pericytes onto growing retinal vessels. Impaired pericyte recruitment to the vessels shows multiple vascular hallmarks of diabetic retinopathy (DR) due to BRB disruption. However, PDGF-B/PDGFRβ signalling is expendable for maintaining BRB integrity in adult mice. Although selective pericyte loss in stable adult retinal vessels surprisingly does not cause BRB disintegration, it sensitizes retinal vascular endothelial cells (ECs) to VEGF-A, leading to upregulation of angiopoietin-2 (Ang2) in ECs through FOXO1 activation and triggering a positive feedback that resembles the pathogenesis of DR. Accordingly, either blocking Ang2 or activating Tie2 greatly attenuates BRB breakdown, suggesting potential therapeutic approaches to reduce retinal damages upon DR progression.

Use of Gabor filters and deep networks in the segmentation of retinal vessel morphology

NASA Astrophysics Data System (ADS)

Leopold, Henry A.; Orchard, Jeff; Zelek, John; Lakshminarayanan, Vasudevan

2017-02-01

The segmentation of retinal morphology has numerous applications in assessing ophthalmologic and cardiovascular disease pathologies. The early detection of many such conditions is often the most effective method for reducing patient risk. Computer aided segmentation of the vasculature has proven to be a challenge, mainly due to inconsistencies such as noise, variations in hue and brightness that can greatly reduce the quality of fundus images. Accurate fundus and/or retinal vessel maps give rise to longitudinal studies able to utilize multimodal image registration and disease/condition status measurements, as well as applications in surgery preparation and biometrics. This paper further investigates the use of a Convolutional Neural Network as a multi-channel classifier of retinal vessels using the Digital Retinal Images for Vessel Extraction database, a standardized set of fundus images used to gauge the effectiveness of classification algorithms. The CNN has a feed-forward architecture and varies from other published architectures in its combination of: max-pooling, zero-padding, ReLU layers, batch normalization, two dense layers and finally a Softmax activation function. Notably, the use of Adam to optimize training the CNN on retinal fundus images has not been found in prior review. This work builds on prior work of the authors, exploring the use of Gabor filters to boost the accuracy of the system to 0.9478 during post processing. The mean of a series of Gabor filters with varying frequencies and sigma values are applied to the output of the network and used to determine whether a pixel represents a vessel or non-vessel.

Mapping by VESGEN of Blood Vessels in the Retinas of ISS Crew Members and Bed Rest Subjects for Increased Understanding of VIIP

NASA Technical Reports Server (NTRS)

Parsons-Wingerter, P. A.; Vizzeri, G.; Tabbi, G.; Zanello, S. B.; Ploutz-Snyder, R.

2014-01-01

Research by NASA has established that significant risks for visual impairment in association with increased intracranial pressure (VIIP) are incurred by microgravity spaceflight, especially long-duration missions. Impairments include decreased near visual acuity, posterior globe flattening, choroidal folds, optic disc edema, and cotton wool spots. Much remains to be learned about the etiology of VIIP before effective countermeasures can be developed. Contributions of retinal vascular remodeling to the etiology of VIIP have not yet been investigated, primarily due to the current lack of ophthalmic tools for precisely measuring progressive pathophysiological remodeling of the retinal microvasculature. Although ophthalmic science and clinical practice are now highly sophisticated at detecting indirect, secondary signs of vascular remodeling such as cotton wool spots that arise during the progression of retinal vascular diseases, methods for quantifying direct, primary vascular changes are not yet established. To help develop insightful analysis of retinal vascular remodeling for aerospace medicine, we will map and quantify by our innovative VESsel GENeration Analysis (VESGEN) software the remodeling status of retinal blood vessels in crew members before and after ISS missions, and in healthy human subjects before and after head-down tilt bed rest. For this proof-of-concept study, we hypothesize that pathophysiological remodeling of retinal blood vessels occurs in coordination with microgravity-induced fluid shifts prior to development of visual impairments. VESGEN analysis in previous research supported by the US National Institutes of Health identified surprising new opportunities to regenerate retinal vessels during early-stage progression of the visually impairing, potentially blinding disease, diabetic retinopathy.

Comparison of retinal vessel measurements using adaptive optics scanning laser ophthalmoscopy and optical coherence tomography.

PubMed

Arichika, Shigeta; Uji, Akihito; Ooto, Sotaro; Muraoka, Yuki; Yoshimura, Nagahisa

2016-05-01

We compared adaptive optics scanning laser ophthalmoscopy (AOSLO) and optical coherence tomography (OCT) vessel caliber measurements. AOSLO videos were acquired from 28 volunteers with healthy eyes. Artery measurements were made 0.5-1 disc diameters away from the optic disc margin. Individual segmented retinal arterial caliber was measured in synchronization with cardiac pulsation and averaged to obtain final horizontal retinal arterial caliber (ACH) and horizontal retinal arterial lumen (ALH). All OCT images were obtained with the Spectralis OCT, a spectral-domain OCT system. Vertical retinal arterial caliber (ACV) and vertical retinal arterial lumen (ALV) were measured on the same artery measured with AOSLO. Measurements made with the two imaging systems were compared. Average ACH, measured with AOSLO, was 123.4 ± 11.2 and average ALH was 101.8 ± 10.2 µm. Average ACV, measured with OCT, was 125.5 ± 11.4 and average ALV was 99.1 ± 10.6 µm. Both arterial caliber (r = 0.767, p < 0.0001) and arterial lumen (r = 0.81, p < 0.0001) measurements were significantly correlated between imaging modalities. Additionally, ACH and ACV were not significantly different (p = 0.16). However, ALH measurements were significantly higher than ALV measurements (p = 0.03). Vessel measurements made with AOSLO and OCT were well correlated. Moreover, plasma is visible and distinguishable from the retinal vessel wall in AOSLO images but not in OCT images. Therefore, AOSLO may measure vessel width more precisely than OCT.

Enhanced visualization of the retinal vasculature using depth information in OCT.

PubMed

de Moura, Joaquim; Novo, Jorge; Charlón, Pablo; Barreira, Noelia; Ortega, Marcos

2017-12-01

Retinal vessel tree extraction is a crucial step for analyzing the microcirculation, a frequently needed process in the study of relevant diseases. To date, this has normally been done by using 2D image capture paradigms, offering a restricted visualization of the real layout of the retinal vasculature. In this work, we propose a new approach that automatically segments and reconstructs the 3D retinal vessel tree by combining near-infrared reflectance retinography information with Optical Coherence Tomography (OCT) sections. Our proposal identifies the vessels, estimates their calibers, and obtains the depth at all the positions of the entire vessel tree, thereby enabling the reconstruction of the 3D layout of the complete arteriovenous tree for subsequent analysis. The method was tested using 991 OCT images combined with their corresponding near-infrared reflectance retinography. The different stages of the methodology were validated using the opinion of an expert as a reference. The tests offered accurate results, showing coherent reconstructions of the 3D vasculature that can be analyzed in the diagnosis of relevant diseases affecting the retinal microcirculation, such as hypertension or diabetes, among others.

An Acute Retinal Model for Evaluating Blood Retinal Barrier Breach and Potential Drugs for Treatment.

PubMed

Wu, Hao; Rodriguez, Ana R; Spur, Bernd W; Venkataraman, Venkat

2016-09-13

A low-cost, easy-to-use and powerful model system is established to evaluate potential treatments that could ameliorate blood retinal barrier breach. An inflammatory factor, histamine, is demonstrated to compromise vessel integrity in the cultured retina through positive staining of IgG outside of the blood vessels. The effects of histamine itself and those of candidate drugs for potential treatments, such as lipoxin A4, are assessed using three parameters: blood vessel leakage via IgG immunostaining, activation of Müller cells via GFAP staining and change in neuronal dendrites through staining for MAP2. Furthermore, the layered organization of the retina allows a detailed analysis of the processes of Müller and ganglion cells, such as changes in width and continuity. While the data presented is with swine retinal culture, the system is applicable to multiple species. Thus, the model provides a reliable tool to investigate the early effects of compromised retinal vessel integrity on different cell types and also to evaluate potential drug candidates for treatment.

Age-Related Alterations in the Retinal Microvasculature, Microcirculation, and Microstructure.

PubMed

Wei, Yantao; Jiang, Hong; Shi, Yingying; Qu, Dongyi; Gregori, Giovanni; Zheng, Fang; Rundek, Tatjana; Wang, Jianhua

2017-07-01

To characterize age-related alterations in the retinal microcirculation, microvascular network, and microstructure in healthy subjects. Seventy-four healthy subjects aged from 18 to 82 years were recruited and divided into four age groups (G1 with age <35 years, G2 with age 35 ∼ 49 years, G3 with age 50 ∼ 64 years, and G4 with age ≥65 years). Custom ultra-high resolution optical coherence tomography (UHR-OCT) was used to acquire six intraretinal layers of the macula. OCT angiography (OCTA) was used to image the retinal microvascular network. The retinal blood flow velocity (BFV) was measured using a Retinal Function Imager (RFI). Compared to G1, G2 had significant thinning of the retinal nerve fiber layer (RNFL) (P < 0.05), while G3 had thinning of the RNFL and ganglion cell and inner plexiform layer (GCIPL) (P < 0.05), in addition to thickening of the outer plexiform layer (OPL) and photoreceptor layer (PR) (P < 0.05). G4 had loss in retinal vessel density, thinning in RNFL and GCIPL, and decrease in venular BFV, in addition to thickening of the OPL and PR (P < 0.05). Age was negatively related to retinal vessel densities, the inner retinal layers, and venular BFV (P < 0.05). By contrast, age was positively related to OPL and PR (P < 0.05). During aging, decreases in retinal vessel density, inner retinal layer thickness, and venular BFV were evident and impacted each other as observed by simultaneous changes in multiple retinal components.

Retinal blood vessel extraction using tunable bandpass filter and fuzzy conditional entropy.

PubMed

Sil Kar, Sudeshna; Maity, Santi P

2016-09-01

Extraction of blood vessels on retinal images plays a significant role for screening of different opthalmologic diseases. However, accurate extraction of the entire and individual type of vessel silhouette from the noisy images with poorly illuminated background is a complicated task. To this aim, an integrated system design platform is suggested in this work for vessel extraction using a sequential bandpass filter followed by fuzzy conditional entropy maximization on matched filter response. At first noise is eliminated from the image under consideration through curvelet based denoising. To include the fine details and the relatively less thick vessel structures, the image is passed through a bank of sequential bandpass filter structure optimized for contrast enhancement. Fuzzy conditional entropy on matched filter response is then maximized to find the set of multiple optimal thresholds to extract the different types of vessel silhouettes from the background. Differential Evolution algorithm is used to determine the optimal gain in bandpass filter and the combination of the fuzzy parameters. Using the multiple thresholds, retinal image is classified as the thick, the medium and the thin vessels including neovascularization. Performance evaluated on different publicly available retinal image databases shows that the proposed method is very efficient in identifying the diverse types of vessels. Proposed method is also efficient in extracting the abnormal and the thin blood vessels in pathological retinal images. The average values of true positive rate, false positive rate and accuracy offered by the method is 76.32%, 1.99% and 96.28%, respectively for the DRIVE database and 72.82%, 2.6% and 96.16%, respectively for the STARE database. Simulation results demonstrate that the proposed method outperforms the existing methods in detecting the various types of vessels and the neovascularization structures. The combination of curvelet transform and tunable bandpass filter is found to be very much effective in edge enhancement whereas fuzzy conditional entropy efficiently distinguishes vessels of different widths. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

The Relationship of Retinal Vessel Geometric Characteristics to the Incidence and Progression of Diabetic Retinopathy.

PubMed

Klein, Ronald; Lee, Kristine E; Danforth, Lorraine; Tsai, Michael Y; Gangnon, Ronald E; Meuer, Stacy E; Wong, Tien Y; Cheung, Carol Y; Klein, Barbara E K

2018-05-17

To examine the relationships of retinal vessel geometric characteristics (RVGCs) to the incidence and progression of diabetic retinopathy (DR). Observational, prospective cohort study. Nine hundred ninety-six persons with type 1 diabetes mellitus (T1DM) and 1370 persons with type 2 diabetes mellitus (T2DM) seen at a baseline examination who were eligible for follow-up examinations at subsequent 5-year intervals. A total of 3846 person-interval data from these follow-up examinations are the basis for the analyses. Diabetic retinopathy and macular edema were assessed by grading of 30° stereoscopic color fundus photographs. Retinal vessel geometric characteristics were assessed using the Singapore I Vessel Assessment program from a digitized copy of 1 of the field 1 fundus photographs obtained at baseline and follow-up. The 5-year incidence of any DR, progression of DR, and incidence of proliferative diabetic retinopathy (PDR) and clinically significant macular edema (CSME) in right eyes. Incident DR occurred in 45%, progression in 32%, PDR in 10%, and CSME in 5%. While adjusting for glycated hemoglobin, duration of diabetes, and other factors, retinal arteriolar simple tortuosity was associated significantly with the incidence of any DR (odds ratio [OR], 1.17; 95% confidence interval [CI], 1.01-1.35). Retinal venular branching angle was associated significantly with progression of DR (OR, 1.18; 95% CI, 1.03-1.36), retinal venular curvature tortuosity was associated significantly with the incidence of PDR (OR, 1.15; 95% CI, 1.01-1.30), and retinal venular branching angle (OR, 1.41; 95% CI, 1.10-1.82) was associated significantly with the incidence of CSME. There were no significant associations of other RVGCs with any of the DR outcomes in the full multivariate model. Inclusion of all possible RVGCs did not improve the predictive value of the models that already included retinal vessel diameter and baseline DR severity level. Retinal vessel geometric characteristics of the retinal venules were associated with progression of DR; however, most of the RVGCs measured from digitized fundus photographs added little to the assessment of risk of incidence and progression of DR when other risk factors were considered in T1DM and T2DM. Copyright © 2018 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Computer-aided diagnostic detection system of venous beading in retinal images

NASA Astrophysics Data System (ADS)

Yang, Ching-Wen; Ma, DyeJyun; Chao, ShuennChing; Wang, ChuinMu; Wen, Chia-Hsien; Lo, ChienShun; Chung, Pau-Choo; Chang, Chein-I.

2000-05-01

The detection of venous beading in retinal images provides an early sign of diabetic retinopathy and plays an important role as a preprocessing step in diagnosing ocular diseases. We present a computer-aided diagnostic system to automatically detect venous beading of blood vessels. It comprises of two modules, referred to as the blood vessel extraction module and the venus beading detection module. The former uses a bell-shaped Gaussian kernel with 12 azimuths to extract blood vessels while the latter applies a neural network-based shape cognitron to detect venous beading among the extracted blood vessels for diagnosis. Both modules are fully computer-automated. To evaluate the proposed system, 61 retinal images (32 beaded and 29 normal images) are used for performance evaluation.

Improving image segmentation performance and quantitative analysis via a computer-aided grading methodology for optical coherence tomography retinal image analysis.

PubMed

Debuc, Delia Cabrera; Salinas, Harry M; Ranganathan, Sudarshan; Tátrai, Erika; Gao, Wei; Shen, Meixiao; Wang, Jianhua; Somfai, Gábor M; Puliafito, Carmen A

2010-01-01

We demonstrate quantitative analysis and error correction of optical coherence tomography (OCT) retinal images by using a custom-built, computer-aided grading methodology. A total of 60 Stratus OCT (Carl Zeiss Meditec, Dublin, California) B-scans collected from ten normal healthy eyes are analyzed by two independent graders. The average retinal thickness per macular region is compared with the automated Stratus OCT results. Intergrader and intragrader reproducibility is calculated by Bland-Altman plots of the mean difference between both gradings and by Pearson correlation coefficients. In addition, the correlation between Stratus OCT and our methodology-derived thickness is also presented. The mean thickness difference between Stratus OCT and our methodology is 6.53 microm and 26.71 microm when using the inner segment/outer segment (IS/OS) junction and outer segment/retinal pigment epithelium (OS/RPE) junction as the outer retinal border, respectively. Overall, the median of the thickness differences as a percentage of the mean thickness is less than 1% and 2% for the intragrader and intergrader reproducibility test, respectively. The measurement accuracy range of the OCT retinal image analysis (OCTRIMA) algorithm is between 0.27 and 1.47 microm and 0.6 and 1.76 microm for the intragrader and intergrader reproducibility tests, respectively. Pearson correlation coefficients demonstrate R(2)>0.98 for all Early Treatment Diabetic Retinopathy Study (ETDRS) regions. Our methodology facilitates a more robust and localized quantification of the retinal structure in normal healthy controls and patients with clinically significant intraretinal features.

Outer Retinal Assessment Using Spectral-Domain Optical Coherence Tomography in Patients With Alzheimer's and Parkinson's Disease.

PubMed

Uchida, Atsuro; Pillai, Jagan A; Bermel, Robert; Bonner-Jackson, Aaron; Rae-Grant, Alexander; Fernandez, Hubert; Bena, James; Jones, Stephen E; Leverenz, James B; Srivastava, Sunil K; Ehlers, Justis P

2018-06-01

To investigate outer retinal parameters among patients with various chronic neurodegenerative disorders by using spectral-domain coherence tomography (OCT) in a prospective cross-sectional cohort study. A total of 132 participants were enrolled following a comprehensive diagnostic evaluation with neurologic, neuropsychology, and magnetic resonance imaging volumetric evaluations. Participants were 50 years or older, either diagnosed with Alzheimer's disease (AD) dementia, amnestic mild cognitive impairment (MCI), non-AD dementia, Parkinson's disease (PD), or age- and sex-matched controls. All participants underwent a macular cube scan for both eyes by using the Cirrus 4000 HD-OCT (Zeiss, Oberkochen, Germany). The OCT image with the best quality was selected for further analysis. Outer retinal parameters including ellipsoid zone mapping and outer nuclear layer metrics were evaluated with a novel software platform. One hundred twenty-four eyes of 124 participants with AD dementia (24 eyes), amnestic MCI (22 eyes), non-AD dementia (20 eyes), PD (22 eyes), and age- and sex-matched controls (36 eyes) were included in the analysis. Eight eyes were excluded either due to the presence of macular disease or poor quality of the OCT image. The mean ages of participants were 65.9 ± 8.9 years. The outer retinal thickness measures did not show any statistical significance between the groups. However, ellipsoid zone to retinal pigment epithelium volume correlated with cognitive testing scores in all study participants. There were no identifiable differences in the outer retinal metrics across neurodegenerative disease groups and controls. The relationship between the degree of cognitive impairment and ellipsoid zone to retinal pigment epithelium volume warrants further study.

Improving image segmentation performance and quantitative analysis via a computer-aided grading methodology for optical coherence tomography retinal image analysis

NASA Astrophysics Data System (ADS)

Cabrera Debuc, Delia; Salinas, Harry M.; Ranganathan, Sudarshan; Tátrai, Erika; Gao, Wei; Shen, Meixiao; Wang, Jianhua; Somfai, Gábor M.; Puliafito, Carmen A.

2010-07-01

We demonstrate quantitative analysis and error correction of optical coherence tomography (OCT) retinal images by using a custom-built, computer-aided grading methodology. A total of 60 Stratus OCT (Carl Zeiss Meditec, Dublin, California) B-scans collected from ten normal healthy eyes are analyzed by two independent graders. The average retinal thickness per macular region is compared with the automated Stratus OCT results. Intergrader and intragrader reproducibility is calculated by Bland-Altman plots of the mean difference between both gradings and by Pearson correlation coefficients. In addition, the correlation between Stratus OCT and our methodology-derived thickness is also presented. The mean thickness difference between Stratus OCT and our methodology is 6.53 μm and 26.71 μm when using the inner segment/outer segment (IS/OS) junction and outer segment/retinal pigment epithelium (OS/RPE) junction as the outer retinal border, respectively. Overall, the median of the thickness differences as a percentage of the mean thickness is less than 1% and 2% for the intragrader and intergrader reproducibility test, respectively. The measurement accuracy range of the OCT retinal image analysis (OCTRIMA) algorithm is between 0.27 and 1.47 μm and 0.6 and 1.76 μm for the intragrader and intergrader reproducibility tests, respectively. Pearson correlation coefficients demonstrate R2>0.98 for all Early Treatment Diabetic Retinopathy Study (ETDRS) regions. Our methodology facilitates a more robust and localized quantification of the retinal structure in normal healthy controls and patients with clinically significant intraretinal features.

Automated construction of arterial and venous trees in retinal images

PubMed Central

Hu, Qiao; Abràmoff, Michael D.; Garvin, Mona K.

2015-01-01

Abstract. While many approaches exist to segment retinal vessels in fundus photographs, only a limited number focus on the construction and disambiguation of arterial and venous trees. Previous approaches are local and/or greedy in nature, making them susceptible to errors or limiting their applicability to large vessels. We propose a more global framework to generate arteriovenous trees in retinal images, given a vessel segmentation. In particular, our approach consists of three stages. The first stage is to generate an overconnected vessel network, named the vessel potential connectivity map (VPCM), consisting of vessel segments and the potential connectivity between them. The second stage is to disambiguate the VPCM into multiple anatomical trees, using a graph-based metaheuristic algorithm. The third stage is to classify these trees into arterial or venous (A/V) trees. We evaluated our approach with a ground truth built based on a public database, showing a pixel-wise classification accuracy of 88.15% using a manual vessel segmentation as input, and 86.11% using an automatic vessel segmentation as input. PMID:26636114

Interactive retinal blood flow analysis of the macular region.

PubMed

Tian, Jing; Somfai, Gábor Márk; Campagnoli, Thalmon R; Smiddy, William E; Debuc, Delia Cabrera

2016-03-01

The study of retinal hemodynamics plays an important role to understand the onset and progression of diabetic retinopathy. In this work, we developed an interactive retinal analysis tool to quantitatively measure the blood flow velocity (BFV) and blood flow rate (BFR) in the macular region using the Retinal Function Imager (RFI). By employing a high definition stroboscopic fundus camera, the RFI device is able to assess retinal blood flow characteristics in vivo. However, the measurements of BFV using a user-guided vessel segmentation tool may induce significant inter-observer differences and BFR is not provided in the built-in software. In this work, we have developed an interactive tool to assess the retinal BFV and BFR in the macular region. Optical coherence tomography data was registered with the RFI image to locate the fovea accurately. The boundaries of the vessels were delineated on a motion contrast enhanced image and BFV was computed by maximizing the cross-correlation of pixel intensities in a ratio video. Furthermore, we were able to calculate the BFR in absolute values (μl/s). Experiments were conducted on 122 vessels from 5 healthy and 5 mild non-proliferative diabetic retinopathy (NPDR) subjects. The Pearson's correlation of the vessel diameter measurements between our method and manual labeling on 40 vessels was 0.984. The intraclass correlation (ICC) of BFV between our proposed method and built-in software was 0.924 and 0.830 for vessels from healthy and NPDR subjects, respectively. The coefficient of variation between repeated sessions was reduced significantly from 22.5% to 15.9% in our proposed method (p<0.001). Copyright © 2015 Elsevier Inc. All rights reserved.

Navigation lymphatic supermicrosurgery for the treatment of cancer-related peripheral lymphedema.

PubMed

Yamamoto, Takumi; Yamamoto, Nana; Numahata, Takao; Yokoyama, Ai; Tashiro, Kensuke; Yoshimatsu, Hidehiko; Narushima, Mitsunaga; Koshima, Isao

2014-02-01

Lymphatic supermicrosurgery is becoming the treatment of choice for refractory lymphedema. Detection and anastomosis of functional lymphatic vessels are important for lymphatic supermicrosurgery. Navigation lymphatic supermicrosurgery was performed using an operating microscope equipped with an integrated near-infrared illumination system (OPMI Pentero Infrared 800; Carl Zeiss, Oberkochen, Germany). Eight patients with extremity lymphedema who underwent navigation lymphatic supermicrosurgery were evaluated. A total of 21 lymphaticovenular anastomoses were performed on 8 limbs through 14 skin incisions. Lymphatic vessels were enhanced by intraoperative microscopic indocyanine green (ICG) lymphography in 12 of the 14 skin incisions, which resulted in early dissection of lymphatic vessels. All anastomoses showed good anastomosis patency after completion of anastomoses. Postoperative extremity lymphedema index decreased in all limbs. Navigation lymphatic supermicrosurgery, in which lymphatic vessels are visualized with intraoperative microscopic ICG lymphography, allows a lymphatic supermicrosurgeon to find and dissect lymphatic vessels earlier and facilitates successful performance of lymphaticovenular anastomosis.

Interactive Retinal Blood Flow Analysis of the Macular Region

PubMed Central

Tian, Jing; Somfai, Gábor Márk; Campagnoli, Thalmon R.; Smiddy, William E.; Debuc, Delia Cabrera

2015-01-01

The study of retinal hemodynamics plays an important role to understand the onset and progression of diabetic retinopathy which is a leading cause of blindness in American adults. In this work, we developed an interactive retinal analysis tool to quantitatively measure the blood flow velocity (BFV) and blood flow rate (BFR) in the macular region using the Retinal Function Imager (RFI-3005, Optical Imaging, Rehovot, Israel). By employing a high definition stroboscopic fundus camera, the RFI device is able to assess retinal blood flow characteristics in vivo even in the capillaries. However, the measurements of BFV using a user-guided vessel segmentation tool may induce significant inter-observer differences and BFR is not provided in the built-in software. In this work, we have developed an interactive tool to assess the retinal BFV as well as BFR in the macular region. Optical coherence tomography (OCT) data from commercially available devices were registered with the RFI image to locate the fovea accurately. The boundaries of the vessels were delineated on a motion contrast enhanced image and BFV was computed by maximizing the cross-correlation of pixel intensities in a ratio video. Furthermore, we were able to calculate the BFR in absolute values (μl/s) which other currently available devices targeting the retinal microcirculation are not yet capable of. Experiments were conducted on 122 vessels from 5 healthy and 5 mild non-proliferative diabetic retinopathy (NPDR) subjects. The Pearson's correlation of the vessel diameter measurements between our method and manual labeling on 40 vessels was 0.984. The intraclass correlation (ICC) of BFV between our proposed method and built-in software were 0.924 and 0.830 for vessels from healthy and NPDR subjects, respectively. The coefficient of variation between repeated sessions was reduced significantly from 22.5% in the RFI built-in software to 15.9% in our proposed method (p<0.001). PMID:26569349

Impaired Retinal Vasodilator Responses in Prediabetes and Type 2 Diabetes

PubMed Central

Lott, Mary E.J.; Slocomb, Julia E.; Shivkumar, Vikram; Smith, Bruce; Quillen, David; Gabbay, Robert A.; Gardner, Thomas W.; Bettermann, Kerstin

2013-01-01

Purpose In diabetes, endothelial dysfunction and subsequent structural damage to blood vessels can lead to heart attacks, retinopathy and strokes. However, it is unclear whether prediabetic subjects exhibit microvascular dysfunction indicating early stages of arteriosclerosis and vascular risk. The purpose of this study was to examine whether retinal reactivity may be impaired early in the hyperglycemic continuum and may be associated with markers of inflammation. Methods Individuals with prediabetes (n = 22), type 2 diabetes (n = 25) and healthy age and body composition matched controls (n = 19) were studied. We used the Dynamic Vessel Analyzer to assess retinal vasoreactivity (percent change in vessel diameter) during a flickering light stimulation. Fasting highly sensitive c-reactive protein (hs-CRP), a marker of inflammation, was measured in blood plasma. Results Prediabetic and diabetic individuals had attenuated peak vasodilator and relative amplitude changes in retinal vein diameters to the flickering light stimulus compared to healthy controls (peak dilation: prediabetic subjects 3.3 ± 1.8 %, diabetic subjects 3.3 ± 2.1% controls 5.6 ± 2.6%, p = .001; relative amplitude: prediabetic subjects 4.3 ± 2.2%, diabetic subjects 5.0 ± 2.6% and control subjects 7.2 ± 3.2%, p = .003). Similar findings were observed in retinal arteries. Levels of hs-CRP were not associated with either retinal vessel response parameters. Conclusion Retinal reactivity was impaired in prediabetic and type 2 diabetic individuals in parallel with reduced insulin sensitivity but not associated with levels of hs-CRP. Retinal vasoreactivity measurements may be a sensitive tool to assess early vascular risk. PMID:23742315

Age-Related Alterations in the Retinal Microvasculature, Microcirculation, and Microstructure

PubMed Central

Wei, Yantao; Jiang, Hong; Shi, Yingying; Qu, Dongyi; Gregori, Giovanni; Zheng, Fang; Rundek, Tatjana; Wang, Jianhua

2017-01-01

Purpose To characterize age-related alterations in the retinal microcirculation, microvascular network, and microstructure in healthy subjects. Methods Seventy-four healthy subjects aged from 18 to 82 years were recruited and divided into four age groups (G1 with age <35 years, G2 with age 35 ∼ 49 years, G3 with age 50 ∼ 64 years, and G4 with age ≥65 years). Custom ultra-high resolution optical coherence tomography (UHR-OCT) was used to acquire six intraretinal layers of the macula. OCT angiography (OCTA) was used to image the retinal microvascular network. The retinal blood flow velocity (BFV) was measured using a Retinal Function Imager (RFI). Results Compared to G1, G2 had significant thinning of the retinal nerve fiber layer (RNFL) (P < 0.05), while G3 had thinning of the RNFL and ganglion cell and inner plexiform layer (GCIPL) (P < 0.05), in addition to thickening of the outer plexiform layer (OPL) and photoreceptor layer (PR) (P < 0.05). G4 had loss in retinal vessel density, thinning in RNFL and GCIPL, and decrease in venular BFV, in addition to thickening of the OPL and PR (P < 0.05). Age was negatively related to retinal vessel densities, the inner retinal layers, and venular BFV (P < 0.05). By contrast, age was positively related to OPL and PR (P < 0.05). Conclusions During aging, decreases in retinal vessel density, inner retinal layer thickness, and venular BFV were evident and impacted each other as observed by simultaneous changes in multiple retinal components. PMID:28744554

Eye Shape Using Partial Coherence Interferometry, Autorefraction and SD OCT

PubMed Central

Clark, Christopher A.; Elsner, Ann E.; Konynenbelt, Benjamin J.

2015-01-01

Purpose Peripheral refraction and retinal shape may influence refractive development. Peripheral refraction has been shown to have a high degree of variability and can take considerable time to perform. SD OCT and peripheral axial length measures may be more reliable, assuming that the retinal position is more important than the peripheral optics of the lens/cornea. Methods 79 subjects right eyes were imaged for this study (age range: 22 to 34 yr, refractive error: −10 to +5.00.) Thirty deg SD OCT (Spectralis, Heidleberg) images were collected in a radial pattern along with peripheral refraction with an autorefractor (Shin-Nippon Auto-refractor) and peripheral axial length measurements with partial coherence interferometry (PCI) (IOLmaster, Zeiss). Statistics were performed using repeat measures ANOVA in SPSS (IBM), Bland-Altman analyses, and regression. All measures were converted to diopters to allow direct comparison. Results SD OCT showed a retinal shape with an increased curvature for myopes compared to emmetropes/hyperopes. This retinal shape change became significant around 5 deg. The SD OCT analysis for retinal shape provides a resolution of 0.026 dipopters, which is about ten times more accurate than using autorefraction or clinical refractive techniques. Bland-Altman analyses suggest that retinal shape measured by SD OCT and the PCI method were more consistent with one another than either was with AR. Conclusions With more accurate measures of retinal shape using SD OCT, consistent differences between emmetrope/hyperopes and myopes were found nearer to the fovea than previously reported. Retinal shape may be influenced by central refractive error, and not merely peripheral optics. Partial coherence interferometry and SD OCT appear to be more accurate than autorefraction, which may be influenced other factors such as fixation and accommodation. Autorefraction does measure the optics directly, which may be a strength of that method. PMID:25437906

Analysis by NASA's VESGEN Software of Retinal Blood Vessels Before and After 70-Day Bed Rest: A Retrospective Study

NASA Technical Reports Server (NTRS)

Raghunandan, Sneha; Vyas, Ruchi J.; Vizzeri, Gianmarco; Taibbi, Giovanni; Zanello, Susana B.; Ploutz-Snyder, Robert; Parsons-Wingerter, Patricia A.

2016-01-01

Significant risks for visual impairment associated with increased intracranial pressure (VIIP) are incurred by microgravity spaceflight, especially long-duration missions. Impairments include decreased near visual acuity, posterior globe flattening, choroidal folds, optic disc edema and cotton wool spots. We hypothesize that microgravity-induced fluid shifts result in pathological changes within the retinal blood vessels that precede development of visual and other ocular impairments. Potential contributions of retinal vascular remodeling to VIIP etiology are therefore being investigated by NASAs innovative VESsel GENeration Analysis (VESGEN) software for two studies: (1) head-down tilt in human subjects before and after 70 days of bed rest, and (2) U.S. crew members before and after ISS missions. VESGEN analysis in previous research supported by the US National Institutes of Health identified surprising new opportunities to regenerate retinal vessels during early-stage, potentially reversible progression of the visually impairing and blinding disease, diabetic retinopathy.

Automated retinal image quality assessment on the UK Biobank dataset for epidemiological studies.

PubMed

Welikala, R A; Fraz, M M; Foster, P J; Whincup, P H; Rudnicka, A R; Owen, C G; Strachan, D P; Barman, S A

2016-04-01

Morphological changes in the retinal vascular network are associated with future risk of many systemic and vascular diseases. However, uncertainty over the presence and nature of some of these associations exists. Analysis of data from large population based studies will help to resolve these uncertainties. The QUARTZ (QUantitative Analysis of Retinal vessel Topology and siZe) retinal image analysis system allows automated processing of large numbers of retinal images. However, an image quality assessment module is needed to achieve full automation. In this paper, we propose such an algorithm, which uses the segmented vessel map to determine the suitability of retinal images for use in the creation of vessel morphometric data suitable for epidemiological studies. This includes an effective 3-dimensional feature set and support vector machine classification. A random subset of 800 retinal images from UK Biobank (a large prospective study of 500,000 middle aged adults; where 68,151 underwent retinal imaging) was used to examine the performance of the image quality algorithm. The algorithm achieved a sensitivity of 95.33% and a specificity of 91.13% for the detection of inadequate images. The strong performance of this image quality algorithm will make rapid automated analysis of vascular morphometry feasible on the entire UK Biobank dataset (and other large retinal datasets), with minimal operator involvement, and at low cost. Copyright © 2016 Elsevier Ltd. All rights reserved.

Corkscrew retinal vessels in neurofibromatosis type 1: report of 12 cases.

PubMed

Muci-Mendoza, R; Ramella, M; Fuenmayor-Rivera, D

2002-03-01

To describe a distinctive spectrum of retinal microvascular abnormalities in 12 patients with neurofibromatosis type 1 (NF-1). This is an observational prospective study of the ocular fundus evaluated by direct ophthalmoscopy with or without fluorescein angiography, to investigate retinal microvascular abnormalities in 32 patients with NF-1 and in 30 control subjects. The evaluation included a complete general and neurological physical examination and in some cases computed tomography, magnetic resonance imaging with gadolinium-DTPA, or both. The occurrence of a distinctive spectrum of retinal microvascular abnormalities is described in 12 patients with NF-1 (37.5%). At the lower end of the spectrum, present in 10 patients, the anomaly consisted of minuscule second or third order tortuous venules, which were called "corkscrew retinal vessels." These were usually isolated but in a few cases multiple. They flow towards the superior or inferior temporal veins. They had a length of one to two disc diameters. They ended either in a minute tuft or vanished on the retinal surface. The upper end of the spectrum was seen in only two patients. One of them had an exceptionally large venous anastomosis on the nasal retina and the other had an arteriovenous malformation extending over one retinal quadrant. None of the patients in the control group had such retinal microvascular abnormalities. The "corkscrew" retinal vessels described in this report constitute a broad spectrum of microvascular markers in NF-1 patients.

Automated Detection of Leakage in Fluorescein Angiography Images with Application to Malarial Retinopathy

PubMed Central

Zhao, Yitian; J. C. MacCormick, Ian; G. Parry, David; Leach, Sophie; A. V. Beare, Nicholas; P. Harding, Simon; Zheng, Yalin

2015-01-01

The detection and assessment of leakage in retinal fluorescein angiogram images is important for the management of a wide range of retinal diseases. We have developed a framework that can automatically detect three types of leakage (large focal, punctate focal, and vessel segment leakage) and validated it on images from patients with malarial retinopathy. This framework comprises three steps: vessel segmentation, saliency feature generation and leakage detection. We tested the effectiveness of this framework by applying it to images from 20 patients with large focal leak, 10 patients with punctate focal leak, and 5,846 vessel segments from 10 patients with vessel leakage. The sensitivity in detecting large focal, punctate focal and vessel segment leakage are 95%, 82% and 81%, respectively, when compared to manual annotation by expert human observers. Our framework has the potential to become a powerful new tool for studying malarial retinopathy, and other conditions involving retinal leakage. PMID:26030010

Automated detection of leakage in fluorescein angiography images with application to malarial retinopathy.

PubMed

Zhao, Yitian; MacCormick, Ian J C; Parry, David G; Leach, Sophie; Beare, Nicholas A V; Harding, Simon P; Zheng, Yalin

2015-06-01

The detection and assessment of leakage in retinal fluorescein angiogram images is important for the management of a wide range of retinal diseases. We have developed a framework that can automatically detect three types of leakage (large focal, punctate focal, and vessel segment leakage) and validated it on images from patients with malarial retinopathy. This framework comprises three steps: vessel segmentation, saliency feature generation and leakage detection. We tested the effectiveness of this framework by applying it to images from 20 patients with large focal leak, 10 patients with punctate focal leak, and 5,846 vessel segments from 10 patients with vessel leakage. The sensitivity in detecting large focal, punctate focal and vessel segment leakage are 95%, 82% and 81%, respectively, when compared to manual annotation by expert human observers. Our framework has the potential to become a powerful new tool for studying malarial retinopathy, and other conditions involving retinal leakage.

Aging decreases CO2 reactivity in the retinal artery, but not in the ocular choroidal vessels; a cross-sectional study.

PubMed

Miyaji, Akane; Ikemura, Tsukasa; Hayashi, Naoyuki

2018-04-14

The CO2 reactivity is often used to assess vascular function, but it is still unclear whether this reactivity is affected by aging. To investigate the effects of aging on the CO2 reactivity in ocular and cerebral vessels, both of which are highly sensitive to hypercapnia, we compared the CO2 reactivity in the retinal artery (RA), retinal and choroidal vessels (RCV), optic nerve head (ONH), and middle cerebral artery (MCA) between young and middle-aged subjects. We measured the CO2 reactivity in 14 young and 11 middle-aged males using laser-speckle flowgraphy during a 3-min inhalation of CO2-rich air. The CO2 reactivity in the RA and ONH were lower in the middle-aged group than in the young group, but no significant effect of age was observed in the RCV or MCA. The CO2 reactivity in the RA and ONH were correlated significantly with age, whereas those in the RCV or MCA were not. These findings suggest that there are regional differences in the effect of age on the CO2 reactivity among not only ocular and cerebral vessels, but also the retinal and choroidal vessels, even though these vessels are in neighboring areas.

A new fluorescent imaging procedure in vivo for evaluation of the retinal microcirculation in rats.

PubMed

Kimura, H; Kiryu, J; Nishiwaki, H; Ogura, Y

1995-03-01

We investigated a new method for in vivo evaluation of the retinal microcirculation in rats using a cell-permeant fluorescent dye, acridine orange (AO), which stains cell nuclei and cytoplasm, and a scanning laser ophthalmoscope (SLO). AO, which binds and interacts with DNA and RNA, and thus stains cell nuclei and cytoplasm, was administered intravenously to rats. Fluorescein angiography was performed after administration of the AO, and fundus images were recorded on S-VHS videotape by means of an SLO. Argon laser was used as an exciter of the dye. The retinal vessels were stained with the dye, rendering the retinal microvasculature clearly visible. Cell nuclei and vessel walls were observed as greater fluorescence and lesser fluorescence, respectively. Leukocytes were also observed as highly fluorescent dots moving through the vessels. The results suggest that SLO visualization of AO uptake by cells may be a useful procedure for the evaluation of retinal microcirculation in vivo in rats.

Retinal vessel enhancement based on the Gaussian function and image fusion

NASA Astrophysics Data System (ADS)

Moraru, Luminita; Obreja, Cristian Dragoş

2017-01-01

The Gaussian function is essential in the construction of the Frangi and COSFIRE (combination of shifted filter responses) filters. The connection of the broken vessels and an accurate extraction of the vascular structure is the main goal of this study. Thus, the outcome of the Frangi and COSFIRE edge detection algorithms are fused using the Dempster-Shafer algorithm with the aim to improve detection and to enhance the retinal vascular structure. For objective results, the average diameters of the retinal vessels provided by Frangi, COSFIRE and Dempster-Shafer fusion algorithms are measured. These experimental values are compared to the ground truth values provided by manually segmented retinal images. We prove the superiority of the fusion algorithm in terms of image quality by using the figure of merit objective metric that correlates the effects of all post-processing techniques.

Influence of myelinated retinal nerve fibers on retinal vessel density measurement with AngioVue OCT angiography.

PubMed

Holló, Gábor

2016-12-01

Myelinated retinal nerve fibers (MRNF) represent an asymptomatic developmental anomaly in which myelin sheaths extend to a group of retinal nerve fibers along their intraocular portion. The additional volume of the myelin sheaths causes displacement of the axons toward the vitreous body. We investigated the effect of localized MRNF on peripapillary vessel density measurement results using optical coherence tomography (OCT) angiography. Peripapillary angioflow density measurements (PAFD, % of the analyzed retinal area) were made with the AngioVue OCT (Optovue Inc., Fremont, USA). In both cases, the predominant position of MRNF was inferonasal to the disk. Vessel density was clearly greater in the area of the MRNF than in the surrounding retina in the optic nerve head (ONH) level, but it was lower than in the surrounding retina in the retinal nerve fiber layer (RNFL) level. In the ONH level, PAFD was higher in the MRNF area than in the spatially corresponding superonasal area (Case 1: 64.6 vs. 57.6 %; Case 2: 65.8 vs. 56.3 %). In contrast, in the RNFL level, PAFD was lower in the MRNF area than in the corresponding superonasal area (Case 1: 60.1 vs. 65.4 %; Case 2: 46.5 vs. 58.5 %). Our cases show that the effect of MRNF on OCT angiography vessel density is different in the different measurement layers. Clinicians may separate decreased vessel density caused by anterior RNFL displacement in MRNF areas from that caused by nerve fiber damage in optic neuropathies by evaluating PAFD in both the ONH and RNFL levels.

A new imaging technique for retinal vessel oximetry: principles and first clinical results in patients with retinal arterial occlusion and diabetic retinopathy

NASA Astrophysics Data System (ADS)

Hammer, M.; Riemer, T.; Vilser, W.; Gehlert, S.; Schweitzer, D.

2009-02-01

The oxygen saturation of blood inside retinal vessels is an essential measure for the estimation of oxygen supply to the tissue as well as its oxygen consumption. In the current approach, the blood oxygenation is measured by a dual-wavelength technique. Using a fundus camera, equipped with a special dual wavelength transmission filter and a color CCD camera, two monochromatic fundus images at 548 nm and 610 nm were recorded simultaneously. The optical densities of retinal vessels for both wavelengths and their ratio, which is known to be proportional to the oxygen saturation, were calculated. From a health control population, mean arterial and venous oxygen saturations were measured of 98+/-10.1% and 65+/-11.7% with reproducibility of 2.52% and 3.25% respectively. In 10 patients with arterial occlusion, a reduction of the arterial oxygen saturation to 78 +/-17% (mean +/- standard deviation, branch arterial occlusion) and 91+/-11% (central arterial occlusion) respectively was found in the occluded vessel. After 5 days on pentoxifilin therapy, the arterial saturation increased to an average of 93+/-12% or 103 +/-6% respectively. In 70 eyes of 42 patients suffering from diabetic retinopathy, an increase of the venous oxygen saturation with the severity of the retinopathy was found (mild nonproliferative retinopathy: 68.4+/-8.2%, moderate non-proliferative retinopathy: 70.5+/-6.8%, severe non-proliferative retinopathy: 72.4+/-7.6%, proliferative retinopathy 75.7+/-8.3%) due to vessel shunting and diabetic changes of the permeability of vessel walls. These first clinical results demonstrate the ability of an accurate measurement of retinal vessel oxygenation with a very simple setup just requiring a special filter in the illumination path of a fundus camera and dedicated software.

Automatic retinal blood vessel parameter calculation in spectral domain optical coherence tomography

NASA Astrophysics Data System (ADS)

Wehbe, Hassan; Ruggeri, Marco; Jiao, Shuliang; Gregori, Giovanni; Puliafito, Carmen A.

2007-02-01

Measurement of retinal blood vessel parameters like the blood blow in the vessels may have significant impact on the study and diagnosis of glaucoma, a leading blinding disease worldwide. Optical coherence tomography (OCT) is a noninvasive imaging technique that can provide not only microscopic structural imaging of the retina but also functional information like the blood flow velocity in the retina. The aim of this study is to automatically extract the parameters of retinal blood vessels like the 3D orientation, the vessel diameters, as well as the corresponding absolute blood flow velocity in the vessel. The parameters were extracted from circular OCT scans around the optic disc. By removing the surface reflection through simple segmentation of the circular OCT scans a blood vessel shadowgram can be generated. The lateral coordinates and the diameter of each blood vessel are extracted from the shadowgram through a series of signal processing. Upon determination of the lateral position and the vessel diameter, the coordinate in the depth direction of each blood vessel is calculated in combination with the Doppler information for the vessel. The extraction of the vessel coordinates and diameter makes it possible to calculate the orientation of the vessel in reference to the direction of the incident sample light, which in turn can be used to calculate the absolute blood flow velocity and the flow rate.

Automated vessel shadow segmentation of fovea-centered spectral-domain images from multiple OCT devices

NASA Astrophysics Data System (ADS)

Wu, Jing; Gerendas, Bianca S.; Waldstein, Sebastian M.; Simader, Christian; Schmidt-Erfurth, Ursula

2014-03-01

Spectral-domain Optical Coherence Tomography (SD-OCT) is a non-invasive modality for acquiring high reso- lution, three-dimensional (3D) cross sectional volumetric images of the retina and the subretinal layers. SD-OCT also allows the detailed imaging of retinal pathology, aiding clinicians in the diagnosis of sight degrading diseases such as age-related macular degeneration (AMD) and glaucoma.1 Disease diagnosis, assessment, and treatment requires a patient to undergo multiple OCT scans, possibly using different scanning devices, to accurately and precisely gauge disease activity, progression and treatment success. However, the use of OCT imaging devices from different vendors, combined with patient movement may result in poor scan spatial correlation, potentially leading to incorrect patient diagnosis or treatment analysis. Image registration can be used to precisely compare disease states by registering differing 3D scans to one another. In order to align 3D scans from different time- points and vendors using registration, landmarks are required, the most obvious being the retinal vasculature. Presented here is a fully automated cross-vendor method to acquire retina vessel locations for OCT registration from fovea centred 3D SD-OCT scans based on vessel shadows. Noise filtered OCT scans are flattened based on vendor retinal layer segmentation, to extract the retinal pigment epithelium (RPE) layer of the retina. Voxel based layer profile analysis and k-means clustering is used to extract candidate vessel shadow regions from the RPE layer. In conjunction, the extracted RPE layers are combined to generate a projection image featuring all candidate vessel shadows. Image processing methods for vessel segmentation of the OCT constructed projection image are then applied to optimize the accuracy of OCT vessel shadow segmentation through the removal of false positive shadow regions such as those caused by exudates and cysts. Validation of segmented vessel shadows uses ground truth vessel shadow regions identified by expert graders at the Vienna Reading Center (VRC). The results presented here are intended to show the feasibility of this method for the accurate and precise extraction of suitable retinal vessel shadows from multiple vendor 3D SD-OCT scans for use in intra-vendor and cross-vendor 3D OCT registration, 2D fundus registration and actual retinal vessel segmentation. The resulting percentage of true vessel shadow segments to false positive segments identified by the proposed system compared to mean grader ground truth is 95%.

Measurement of retinal wall-to-lumen ratio by adaptive optics retinal camera: a clinical research.

PubMed

Meixner, Eva; Michelson, Georg

2015-11-01

To measure the wall-to-lumen ratio (WLR) and the cross-sectional area of the vascular wall (WCSA) of retinal arterioles by an Adaptive Optics (AO) retinal camera. Forty-seven human subjects were examined and their medical history was explored. WLR and WCSA were measured on the basis of retinal arteriolar wall thickness (VW), lumen diameter (LD) and vessel diameter (VD) assessed by rtx1 Adaptive Optics retinal camera. WLR was calculated by the formula [Formula: see text]. Arterio-venous ratio (AVR) and microvascular abnormalities were attained by quantitative and qualitative assessment of fundus photographs. Influence of age, arterial hypertension, body mass index (BMI) and retinal microvascular abnormalities on the WLR was examined. An age-adjusted WLR was created to test influences on WLR independently of age. Considering WLR and WCSA, a distinction between eutrophic and hypertrophic retinal remodeling processes was possible. The intra-observer variability (IOV) was 6 % ± 0.9 for arteriolar wall thickness and 2 % ± 0.2 for arteriolar wall thickness plus vessel lumen. WLR depended significantly on the wall thickness (r = 0.715; p < 0.01) of retinal arterioles, but was independent of the total vessel diameter (r = 0.052; p = 0.728). WLR correlated significantly with age (r = 0.769; p < 0.01). Arterial hypertension and a higher BMI were significantly associated with an increased age-adjusted WLR. WLR correlated significantly with the stage of microvascular abnormalities. 55 % of the hypertensive subjects and 11 % of the normotensive subjects showed eutrophic remodeling, while hypertrophic remodeling was not detectable. WLR correlated inversely with AVR. AVR was independent of the arteriolar wall thickness, age and arterial hypertension. The technique of AO retinal imaging allows a direct measurement of the retinal vessel wall and lumen diameter with good intra-observer variability. Age, arterial hypertension and an elevated BMI level are significantly associated with an increased WLR. The wall-to-lumen ratio measured by AO can be used to detect structural retinal microvascular alterations in an early stage of remodeling processes.

Automated measurement of retinal vascular tortuosity.

PubMed Central

Hart, W. E.; Goldbaum, M.; Côté, B.; Kube, P.; Nelson, M. R.

1997-01-01

Automatic measurement of blood vessel tortuosity is a useful capability for automatic ophthalmological diagnostic tools. We describe a suite of automated tortuosity measures for blood vessel segments extracted from RGB retinal images. The tortuosity measures were evaluated in two classification tasks: (1) classifying the tortuosity of blood vessel segments and (2) classifying the tortuosity of blood vessel networks. These tortuosity measures were able to achieve a classification rate of 91% for the first problem and 95% on the second problem, which confirms that they capture much of the ophthalmologists' notion of tortuosity. Images Figure 1 PMID:9357668

Relationship Between Retinal Blood Flow and Serum Adiponectin Concentrations in Patients With Type 2 Diabetes Mellitus.

PubMed

Omae, Tsuneaki; Nagaoka, Taiji; Yoshida, Akitoshi

2015-06-01

To study the relationship between retinal microcirculation and serum adiponectin, an important adipocytokine secreted by adipocytes, concentrations in patients with type 2 diabetes mellitus. Using a laser Doppler velocimetry system, we simultaneously measured the retinal blood flow (RBF) values and retinal vessel diameter and blood velocity in 64 consecutive Japanese patients (mean age ± SD, 59.8 ± 10.4 years) with type 2 diabetes with no or mild nonproliferative diabetic retinopathy. We compared the values with the RBF and serum adiponectin concentrations in these patients. The patients were divided into two groups based on sex (33 males, 31 females). The plasma adiponectin concentrations were correlated positively with the retinal vessel diameter (r = 0.480; P = 0.005), retinal blood velocity (r = 0.399; P = 0.02), and RBF (r = 0.518; P = 0.002) and correlated negatively with the retinal arterial vascular resistance (r = -0.598; P = 0.0002) in males, but not females, with type 2 diabetes with early-stage diabetic retinopathy. Multiple regression analysis showed that the plasma adiponectin level was independently and positively correlated with RBF and negatively correlated with retinal arterial vascular resistance. Our results indicated that a high concentration of serum adiponectin may be associated with increased RBF, probably via the increased blood velocity and dilated vessel diameter in males with type 2 diabetes with early-phase diabetic retinopathy.

Middle Cerebral Artery, Ophthalmic Artery, and Multibranch Retinal Vessel Occlusion After Cosmetic Autologous Fat Transfer to Forehead.

PubMed

Roshandel, Danial; Soheilian, Masoud; Pakravan, Mohammad; Aghayan, Sara; Peyman, Gholam A

2015-05-01

A 65-year-old woman with left hemiparesis and sudden loss of visual acuity in her right eye presented a few hours after cosmetic injection of autologous fat to her forehead. Right eye visual acuity was no light perception. Funduscopy revealed widespread retinal whitening and multibranch retinal vessel occlusion. Fluorescein angiography showed markedly delayed choroidal and retinal filling together with occlusion of multiple branches of retinal arteries and veins. On magnetic resonance imaging of the brain, multiple lesions compatible with recent infarction were detected. The authors diagnosed multibranch retinal artery and vein occlusion in the right ophthalmic and middle cerebral arteries due to fat emboli. This case emphasizes the need to reevaluate the safety of such aesthetic procedures, particularly in the facial zone to prevent devastating complications. Copyright 2015, SLACK Incorporated.

Corkscrew retinal vessels in neurofibromatosis type 1: report of 12 cases

PubMed Central

Muci-Mendoza, R; Ramella, M; Fuenmayor-Rivera, D

2002-01-01

Aim: To describe a distinctive spectrum of retinal microvascular abnormalities in 12 patients with neurofibromatosis type 1 (NF-1). Methods: This is an observational prospective study of the ocular fundus evaluated by direct ophthalmoscopy with or without fluorescein angiography, to investigate retinal microvascular abnormalities in 32 patients with NF-1 and in 30 control subjects. The evaluation included a complete general and neurological physical examination and in some cases computed tomography, magnetic resonance imaging with gadolinium-DTPA, or both. Results: The occurrence of a distinctive spectrum of retinal microvascular abnormalities is described in 12 patients with NF-1 (37.5%). At the lower end of the spectrum, present in 10 patients, the anomaly consisted of minuscule second or third order tortuous venules, which were called “corkscrew retinal vessels.” These were usually isolated but in a few cases multiple. They flow towards the superior or inferior temporal veins. They had a length of one to two disc diameters. They ended either in a minute tuft or vanished on the retinal surface. The upper end of the spectrum was seen in only two patients. One of them had an exceptionally large venous anastomosis on the nasal retina and the other had an arteriovenous malformation extending over one retinal quadrant. None of the patients in the control group had such retinal microvascular abnormalities. Conclusion: The “corkscrew” retinal vessels described in this report constitute a broad spectrum of microvascular markers in NF-1 patients. PMID:11864883

Retinal artery-vein classification via topology estimation

PubMed Central

Estrada, Rolando; Allingham, Michael J.; Mettu, Priyatham S.; Cousins, Scott W.; Tomasi, Carlo; Farsiu, Sina

2015-01-01

We propose a novel, graph-theoretic framework for distinguishing arteries from veins in a fundus image. We make use of the underlying vessel topology to better classify small and midsized vessels. We extend our previously proposed tree topology estimation framework by incorporating expert, domain-specific features to construct a simple, yet powerful global likelihood model. We efficiently maximize this model by iteratively exploring the space of possible solutions consistent with the projected vessels. We tested our method on four retinal datasets and achieved classification accuracies of 91.0%, 93.5%, 91.7%, and 90.9%, outperforming existing methods. Our results show the effectiveness of our approach, which is capable of analyzing the entire vasculature, including peripheral vessels, in wide field-of-view fundus photographs. This topology-based method is a potentially important tool for diagnosing diseases with retinal vascular manifestation. PMID:26068204

Fundus spectroscopy and studies in retinal oximetry using intravitreal illumination

NASA Astrophysics Data System (ADS)

Salyer, David Alan

This dissertation documents the development of a new illumination technique for use in the studies of retinal oximetry and fundus spectroscopy. Intravitreal illumination is a technique where the back of the eye is illuminated trans-sclerally using a scanning monochromator coupled into a fiber optic illuminator. Retinal oximetry is the process of measuring the oxygen saturation of blood contained in retinal vessels by quantitative measurement of the characteristic color shift seen as blood oxygen saturation changes from oxygenated blood (reddish) to deoxygenated blood (bluish). Retinal oximetry was first attempted in 1963 but due to a variety of problems with accuracy and difficulty of measurement, has not matured to the point of clinical acceptability or commercial viability. Accurate retinal oximetry relies in part on an adequate understanding of the spectral reflectance characteristics of the fundus. The use of intravitreal illumination allows new investigations into the spectral reflectance properties of the fundus. The results of much research in fundus reflectance and retinal oximetry is detailed in this document, providing new insight into both of these related fields of study. Intravitreal illumination has been used to study retinal vessel oximetry and fundus reflectometry resulting in several important findings that are presented in this document. Studies on enucleated swine eyes have provided new insight into the bidirectional reflectance distribution function of the fundus. Research on live swine has shown accurate measurement of retinal vessel oxygen saturation and provided the first in vivo spectral transmittance measurement of the sensory retina. A secondary discovery during this research suggests that vitrectomy alters the retinal vasculature, an finding that should spawn new research in its own right.

Feasibility of laser-targeted photoocclusion of the choriocapillary layer in rats.

PubMed

Asrani, S; Zou, S; D'Anna, S; Lutty, G; Vinores, S A; Goldberg, M F; Zeimer, R

1997-12-01

A new method, laser-targeted photoocclusion, was developed to occlude choroidal neovascularization while minimizing damage to the overlying retina. The ability to occlude normal choriocapillary layer in rats was evaluated as a first test of the feasibility of treating choroidal neovascularization with this method. A photosensitive agent, aluminum phthalocyanine tetrasulfonate, encapsulated in heat-sensitive liposomes, was administered intravenously along with carboxyfluorescein liposomes. A low-power argon laser (retinal power density of 5.7 W/cm2) locally released a photosensitizer bolus, monitored by the simultaneous release of carboxyfluorescein. A diode laser (operating at 675 nm with a retinal power density of 0.27 W/cm2) activated the photosensitizer with its release. Vessels in the choriocapillary layer were occluded at day 3 after laser treatment and remained unchanged during the 30-day follow-up. Larger choroidal vessels and retinal capillaries remained perfused. Control experiments excluded possible effects of heat or activation of free photosensitizer. Pilot histologic studies showed no damage to the retinal pigment epithelium. Laser-targeted photoocclusion caused selective occlusion of normal choriocapillaries while sparing overlying retinal pigment epithelium and retinal vessels. The method has potential as a treatment of choroidal neovascularization that may minimize iatrogenic loss of vision.

Multi-level deep supervised networks for retinal vessel segmentation.

PubMed

Mo, Juan; Zhang, Lei

2017-12-01

Changes in the appearance of retinal blood vessels are an important indicator for various ophthalmologic and cardiovascular diseases, including diabetes, hypertension, arteriosclerosis, and choroidal neovascularization. Vessel segmentation from retinal images is very challenging because of low blood vessel contrast, intricate vessel topology, and the presence of pathologies such as microaneurysms and hemorrhages. To overcome these challenges, we propose a neural network-based method for vessel segmentation. A deep supervised fully convolutional network is developed by leveraging multi-level hierarchical features of the deep networks. To improve the discriminative capability of features in lower layers of the deep network and guide the gradient back propagation to overcome gradient vanishing, deep supervision with auxiliary classifiers is incorporated in some intermediate layers of the network. Moreover, the transferred knowledge learned from other domains is used to alleviate the issue of insufficient medical training data. The proposed approach does not rely on hand-crafted features and needs no problem-specific preprocessing or postprocessing, which reduces the impact of subjective factors. We evaluate the proposed method on three publicly available databases, the DRIVE, STARE, and CHASE_DB1 databases. Extensive experiments demonstrate that our approach achieves better or comparable performance to state-of-the-art methods with a much faster processing speed, making it suitable for real-world clinical applications. The results of cross-training experiments demonstrate its robustness with respect to the training set. The proposed approach segments retinal vessels accurately with a much faster processing speed and can be easily applied to other biomedical segmentation tasks.

Blood vessel segmentation in modern wide-field retinal images in the presence of additive Gaussian noise.

PubMed

Asem, Morteza Modarresi; Oveisi, Iman Sheikh; Janbozorgi, Mona

2018-07-01

Retinal blood vessels indicate some serious health ramifications, such as cardiovascular disease and stroke. Thanks to modern imaging technology, high-resolution images provide detailed information to help analyze retinal vascular features before symptoms associated with such conditions fully develop. Additionally, these retinal images can be used by ophthalmologists to facilitate diagnosis and the procedures of eye surgery. A fuzzy noise reduction algorithm was employed to enhance color images corrupted by Gaussian noise. The present paper proposes employing a contrast limited adaptive histogram equalization to enhance illumination and increase the contrast of retinal images captured from state-of-the-art cameras. Possessing directional properties, the multistructure elements method can lead to high-performance edge detection. Therefore, multistructure elements-based morphology operators are used to detect high-quality image ridges. Following this detection, the irrelevant ridges, which are not part of the vessel tree, were removed by morphological operators by reconstruction, attempting also to keep the thin vessels preserved. A combined method of connected components analysis (CCA) in conjunction with a thresholding approach was further used to identify the ridges that correspond to vessels. The application of CCA can yield higher efficiency when it is locally applied rather than applied on the whole image. The significance of our work lies in the way in which several methods are effectively combined and the originality of the database employed, making this work unique in the literature. Computer simulation results in wide-field retinal images with up to a 200-deg field of view are a testimony of the efficacy of the proposed approach, with an accuracy of 0.9524.

Ambulatory Aortic Stiffness Is Associated With Narrow Retinal Arteriolar Caliber in Hypertensives: The SAFAR Study.

PubMed

Aissopou, Evaggelia K; Argyris, Antoniοs A; Nasothimiou, Efthimia G; Konstantonis, George D; Tampakis, Kostas; Tentolouris, Nikolaos; Papathanassiou, Miltiadis; Theodossiadis, Panagiotis G; Papaioannou, Theodoros G; Stehouwer, Coen D A; Sfikakis, Petros P; Protogerou, Athanassios D

2016-05-01

Arterial stiffness measured under static conditions reclassifies significantly cardiovascular (CV) risk and associates with narrower retinal arterioles. However, arterial stiffness exhibits circadian variation, thus single static stiffness recordings do not correspond to the "usual" 24 hr, awake, and asleep average arterial stiffness. We aimed to test the hypothesis that ambulatory 24 hr, awake, and asleep aortic (a) pulse wave velocity (PWV) associate with retinal vessel calibers, independently of confounders and of static arterial stiffness, in hypertensive individuals free from diabetes and CV disease. Digital retinal images were obtained (181 individuals, age: 53.9±10.7 years, 55.2% men) and retinal vessel calibers were measured with validated software to determine central retinal arteriolar and venular equivalents (CRAE and CRVE, respectively); ambulatory (24 hr, awake, asleep) and static office aPWV were estimated by Mobil-O-Graph; and static office carotid to femoral (cf) PWV by SphygmoCor. Regression analysis performed in 320 gradable retinal images showed that, after adjustment for confounders: (i) ambulatory aPWV was significantly associated with narrower retinal arterioles but not with venules; (ii) asleep aPWV had stronger associations with CRAE than awake aPWV; (iii) both ambulatory aPWV and cfPWV were associated mutually independently with narrower retinal arterioles; aPWV introduction in the model of cfPWV, improved model's R2 (P = 0.012). Similar discriminatory ability of 24 hr aPWV and of cfPWV to detect the presence of retinal arteriolar narrowing was found. Ambulatory aPWV, estimated by an operator-independent method, provides additional information to cfPWV regarding the associations of arterial stiffness with the retinal vessel calibers. © American Journal of Hypertension, Ltd 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Rotation invariant eigenvessels and auto-context for retinal vessel detection

NASA Astrophysics Data System (ADS)

Montuoro, Alessio; Simader, Christian; Langs, Georg; Schmidt-Erfurth, Ursula

2015-03-01

Retinal vessels are one of the few anatomical landmarks that are clearly visible in various imaging modalities of the eye. As they are also relatively invariant to disease progression, retinal vessel segmentation allows cross-modal and temporal registration enabling exact diagnosing for various eye diseases like diabetic retinopathy, hypertensive retinopathy or age-related macular degeneration (AMD). Due to the clinical significance of retinal vessels many different approaches for segmentation have been published in the literature. In contrast to other segmentation approaches our method is not specifically tailored to the task of retinal vessel segmentation. Instead we utilize a more general image classification approach and show that this can achieve comparable results. In the proposed method we utilize the concepts of eigenfaces and auto-context. Eigenfaces have been described quite extensively in the literature and their performance is well known. They are however quite sensitive to translation and rotation. The former was addressed by computing the eigenvessels in local image windows of different scales, the latter by estimating and correcting the local orientation. Auto-context aims to incorporate automatically generated context information into the training phase of classification approaches. It has been shown to improve the performance of spinal cord segmentation4 and 3D brain image segmentation. The proposed method achieves an area under the receiver operating characteristic (ROC) curve of Az = 0.941 on the DRIVE data set, being comparable to current state-of-the-art approaches.

Computer-aided diagnosis of retinopathy in retinal fundus images of preterm infants via quantification of vascular tortuosity

PubMed Central

Oloumi, Faraz; Rangayyan, Rangaraj M.; Ells, Anna L.

2016-01-01

Abstract. Retinopathy of prematurity (ROP), a disorder of the retina occurring in preterm infants, is the leading cause of preventable childhood blindness. An active phase of ROP that requires treatment is associated with the presence of plus disease, which is diagnosed clinically in a qualitative manner by visual assessment of the existence of a certain level of increase in the thickness and tortuosity of retinal vessels. The present study performs computer-aided diagnosis (CAD) of plus disease via quantitative measurement of tortuosity in retinal fundus images of preterm infants. Digital image processing techniques were developed for the detection of retinal vessels and measurement of their tortuosity. The total lengths of abnormally tortuous vessels in each quadrant and the entire image were then computed. A minimum-length diagnostic-decision-making criterion was developed to assess the diagnostic sensitivity and specificity of the values obtained. The area (Az) under the receiver operating characteristic curve was used to assess the overall diagnostic accuracy of the methods. Using a set of 19 retinal fundus images of preterm infants with plus disease and 91 without plus disease, the proposed methods provided an overall diagnostic accuracy of Az=0.98. Using the total length of all abnormally tortuous vessel segments in an image, our techniques are capable of CAD of plus disease with high accuracy without the need for manual selection of vessels to analyze. The proposed methods may be used in a clinical or teleophthalmological setting. PMID:28018938

Relaxin 2 fails to lower intraocular pressure and to dilate retinal vessels in rats.

PubMed

Hampel, Ulrike; Träger, Katharina; Liu, Hanhan; Teister, Julia; Grus, Franz; Prokosch-Willing, Verena

2018-03-13

Recently, the vasodilator relaxin 2 has been introduced as a treatment for acute heart failure. However, its role on vessels of the eye and intraocular pressure (IOP) remains unclear though it has been hypothesized to induce a decrease IOP after intramuscular injection in humans. We aimed to test whether the hormone relaxin 2 lowers IOP and dilates retinal vessels in animals. The IOP of female Sprague-Dawley rats before and after application of relaxin 2 was measured using an Icare Tonolab device calibrated for rats. Recombinant human relaxin 2 in phosphate-buffered saline with 0.1% bovine serum albumin was either applied as eye drops (1000, 2000 or 3000 ng/ml), injected intravitreally (500 ng/ml) or intravenously (13.3 μg/kg body weight). Retinal vessel thickness was monitored using infrared fundus images compiled with optical coherence tomography (Heidelberg Engineering) before and several time points after application of relaxin 2. Neither topical nor intravitreous or intravenous application of relaxin 2 lowered the IOP or changed the arterial or venous vessel diameter after 1 or 3 h after application. Now that relaxin 2 is more easily available, the hormone came again into focus as a potential glaucoma therapeutic. However, our study in rats could not support the hypothesis that relaxin 2 lowers IOP or dilates retinal vessels.

Quantification of oxygen-induced retinopathy in the mouse: a model of vessel loss, vessel regrowth and pathological angiogenesis

PubMed Central

Connor, Kip M; Krah, Nathan M; Dennison, Roberta J; Aderman, Christopher M; Chen, Jing; Guerin, Karen I; Sapieha, Przemyslaw; Stahl, Andreas; Willett, Keirnan L; Smith, Lois E H

2013-01-01

The mouse model of oxygen-induced retinopathy (OIR) has been widely used in studies related to retinopathy of prematurity, proliferative diabetic retinopathy and in studies evaluating the efficacy of antiangiogenic compounds. In this model, 7-d-old (P7) mouse pups with nursing mothers are subjected to hyperoxia (75% oxygen) for 5 d, which inhibits retinal vessel growth and causes significant vessel loss. on P12, mice are returned to room air and the hypoxic avascular retina triggers both normal vessel regrowth and retinal neovascularization (NV), which is maximal at P17. neovascularization spontaneously regresses between P17 and P25. although the OIR model has been the cornerstone of studies investigating proliferative retinopathies, there is currently no harmonized protocol to assess aspects of angiogenesis and treatment outcome. In this protocol we describe standards for mouse size, sample size, retinal preparation, quantification of vascular loss, vascular regrowth, NV and neovascular regression. PMID:19816419

Novel Computerized Method for Measurement of Retinal Vessel Diameters

PubMed Central

Guedri, Hichem; Ben Abdallah, Mariem; Echouchene, Fraj; Belmabrouk, Hafedh

2017-01-01

Several clinical studies reveal the relationship between alterations in the topologies of the human retinal blood vessel, the outcrop and the disease evolution, such as diabetic retinopathy, hypertensive retinopathy, and macular degeneration. Indeed, the detection of these vascular changes always has gaps. In addition, the manual steps are slow, which may be subjected to a bias of the perceiver. However, we can overcome these troubles using computer algorithms that are quicker and more accurate. This paper presents and investigates a novel method for measuring the blood vessel diameter in the retinal image. The proposed method is based on a thresholding segmentation and thinning step, followed by the characteristic point determination step by the Douglas-Peucker algorithm. Thereafter, it uses the active contours to detect vessel contour. Finally, Heron’s Formula is applied to assure the calculation of vessel diameter. The obtained results for six sample images showed that the proposed method generated less errors compared to other techniques, which confirms the high performance of the proposed method. PMID:28536355

Retinal imaging analysis based on vessel detection.

PubMed

Jamal, Arshad; Hazim Alkawaz, Mohammed; Rehman, Amjad; Saba, Tanzila

2017-07-01

With an increase in the advancement of digital imaging and computing power, computationally intelligent technologies are in high demand to be used in ophthalmology cure and treatment. In current research, Retina Image Analysis (RIA) is developed for optometrist at Eye Care Center in Management and Science University. This research aims to analyze the retina through vessel detection. The RIA assists in the analysis of the retinal images and specialists are served with various options like saving, processing and analyzing retinal images through its advanced interface layout. Additionally, RIA assists in the selection process of vessel segment; processing these vessels by calculating its diameter, standard deviation, length, and displaying detected vessel on the retina. The Agile Unified Process is adopted as the methodology in developing this research. To conclude, Retina Image Analysis might help the optometrist to get better understanding in analyzing the patient's retina. Finally, the Retina Image Analysis procedure is developed using MATLAB (R2011b). Promising results are attained that are comparable in the state of art. © 2017 Wiley Periodicals, Inc.

Accurate Image Analysis of the Retina Using Hessian Matrix and Binarisation of Thresholded Entropy with Application of Texture Mapping

PubMed Central

Yin, Xiaoxia; Ng, Brian W-H; He, Jing; Zhang, Yanchun; Abbott, Derek

2014-01-01

In this paper, we demonstrate a comprehensive method for segmenting the retinal vasculature in camera images of the fundus. This is of interest in the area of diagnostics for eye diseases that affect the blood vessels in the eye. In a departure from other state-of-the-art methods, vessels are first pre-grouped together with graph partitioning, using a spectral clustering technique based on morphological features. Local curvature is estimated over the whole image using eigenvalues of Hessian matrix in order to enhance the vessels, which appear as ridges in images of the retina. The result is combined with a binarized image, obtained using a threshold that maximizes entropy, to extract the retinal vessels from the background. Speckle type noise is reduced by applying a connectivity constraint on the extracted curvature based enhanced image. This constraint is varied over the image according to each region's predominant blood vessel size. The resultant image exhibits the central light reflex of retinal arteries and veins, which prevents the segmentation of whole vessels. To address this, the earlier entropy-based binarization technique is repeated on the original image, but crucially, with a different threshold to incorporate the central reflex vessels. The final segmentation is achieved by combining the segmented vessels with and without central light reflex. We carry out our approach on DRIVE and REVIEW, two publicly available collections of retinal images for research purposes. The obtained results are compared with state-of-the-art methods in the literature using metrics such as sensitivity (true positive rate), selectivity (false positive rate) and accuracy rates for the DRIVE images and measured vessel widths for the REVIEW images. Our approach out-performs the methods in the literature. PMID:24781033

The short-term effect of flavonoid-rich dark chocolate on retinal vessel diameter in glaucoma patients and age-matched controls.

PubMed

Terai, Naim; Gedenk, Alexandra; Spoerl, Eberhard; Pillunat, Lutz E; Stodtmeister, Richard

2014-08-01

To investigate the effect of flavonoid-rich dark chocolate and non-flavonoid-rich white chocolate on retinal vessel diameter in glaucoma patients and age-matched controls. Thirty glaucoma patients and 30 age-matched subjects were assigned to dark or white chocolate by randomization with forced equal distribution. The number in each of the four groups was 15. Measured parameters included systemic blood pressure (BP), blood glucose levels, static retinal vessel analysis, as measured by central retinal artery equivalent (CRAE) (which relates to the diameter of the central retinal artery), central retinal vein equivalent (CRVE) (which relates to the diameter of central retinal vein) and the arterio-venous ratio (AVR), which represents the CRAE/CRVE ratio, dynamic retinal vessel analysis as measured by the change in vessel diameter in response to flicker light stimulation. Three recording cycles from each were averaged. Blood pressure parameters (systolic BP, diastolic BP and pulse), IOP and blood glucose levels did not differ significantly between both groups before and after consumption of white or dark chocolate. Static vessel analysis did not show any significant changes in CRAE, CRVE or AVR before and after dark or white chocolate in both groups (p > 0.05). Mean dilatation of the venules in the control group was 3.2 ± 0.9 % before dark chocolate and 4.2 ± 1.4 % after dark chocolate intake, which was statistically significantly different (p = 0.01). Mean dilatation of the arterioles in the control group was 2.8 ± 1.8 % before dark chocolate and 3.5 ± 1.8 % after dark chocolate intake with a trend to statistical significance (p = 0.14), but not reaching the significance level. Mean diameter changes in the glaucoma group did not show any significant differences after dark chocolate consumption. The present study showed a significant improvement of venous vasodilatation 2 hr after dark chocolate intake in the control group, but not in the glaucoma group. This effect might be indicative of an increased bioavailability of nitric oxide (NO) after dark chocolate consumption. The lack of finding a significant venous response after dark chocolate in the glaucoma group might be related to the already impaired endothelial function in these patients. © 2014 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

A possible early sign of hydroxychloroquine macular toxicity.

PubMed

Brandao, Livia M; Palmowski-Wolfe, Anja M

2016-02-01

Hydroxychloroquine (HCQ) has a low risk of retinal toxicity which increases dramatically with a cumulative dose of >1000 g. Here we report a case of HCQ macular toxicity presentation in a young patient with a cumulative dose of 438 g. A 15-year-old female started attending annual consultations for retinal toxicity screening in our clinic after 3 years of HCQ treatment for juvenile idiopathic dermatomyositis. She had been diagnosed at age 12 and had been on hydroxychloroquine 200 mg/day, cyclosporin 150 mg/day and vitamin D3 since. Screening consultations included: complete ophthalmologic examination, automated perimetry (AP, M Standard, Octopus 101, Haag-Streit), multifocal electroretinogram (VERIS 6.06™, FMSIII), optical coherence tomography (OCT, fast macular protocol, Cirrus SD-OCT, Carl Zeiss), fundus autofluorescence imaging (Spectralis OCT, Heidelberg Engineering Inc.) and color testing (Farnsworth-Panel-D-15). After 5 years of treatment, AP demonstrated reduced sensibility in only one extra-foveal point in each eye (p < 0.2). Even though other exams showed no alteration and the cumulative dose was only around 353 g, consultations were increased to every 6 months. After 2-year follow-up, that is, 7 years of HCQ, a bilateral paracentral macula thinning was evident on OCT, suggestive of bull's eye maculopathy. However, the retinal pigmented epithelium appeared intact and AP was completely normal in both eyes. Further evaluation with ganglion cell analysis (GCA = ganglion cell + inner plexiform layer, Cirrus SD-OCT, Carl Zeiss) showed a concentric thinning of this layer in the same area. Although daily and cumulative doses were still under the high toxicity risk parameters, HCQ was suspended. At a follow-up 1 year later, visual acuity was 20/16 without any further changes in OCT or on any other exam. This may be the first case report of insidious bull's eye maculopathy exclusively identified using OCT thickness analysis, in a patient in whom both cumulative and daily dosages were under the high-risk parameters for screening and the averages reported in studies. As ganglion cell analysis has only recently become available, further studies are needed to understand toxicity mechanisms and maybe review screening recommendations.

Assessing blood vessel perfusion and vital signs through retinal imaging photoplethysmography.

PubMed

Hassan, Harnani; Jaidka, Sheila; Dwyer, Vincent M; Hu, Sijung

2018-05-01

One solution to the global challenge of increasing ocular disease is a cost-effective technique for rapid screening and assessment. Current ophthalmic imaging techniques, e.g. scanning and ocular blood flow systems, are expensive, complex to operate and utilize invasive contrast agents during assessment. The work presented here demonstrates a simple retinal imaging photoplethysmography (iPPG) system with the potential to provide screening, diagnosis, monitoring and assessment that is non-invasive, painless and radiationless. Time series of individual retinal blood vessel images, captured with an eye fundus camera, are processed using standard filtering, amplitude demodulation and principle component analysis (PCA) methods to determine the values of the heart rate (HR) and respiration rate (RR), which are in compliance with simultaneously obtained measurements using commercial pulse oximetry. It also seems possible that some information on the dynamic changes in oxygen saturation levels ( SpO 2 ) in a retinal blood vessel may also be obtained. As a consequence, the retinal iPPG modality system demonstrates a potential avenue for rapid ophthalmic screening, and even early diagnosis, against ocular disease without the need for fluorescent or contrast agents.

Towards Vision-Based Control of a Handheld Micromanipulator for Retinal Cannulation in an Eyeball Phantom

PubMed Central

Becker, Brian C.; Yang, Sungwook; MacLachlan, Robert A.; Riviere, Cameron N.

2012-01-01

Injecting clot-busting drugs such as t-PA into tiny vessels thinner than a human hair in the eye is a challenging procedure, especially since the vessels lie directly on top of the delicate and easily damaged retina. Various robotic aids have been proposed with the goal of increasing safety by removing tremor and increasing precision with motion scaling. We have developed a fully handheld micromanipulator, Micron, that has demonstrated reduced tremor when cannulating porcine retinal veins in an “open sky” scenario. In this paper, we present work towards handheld robotic cannulation with the goal of vision-based virtual fixtures guiding the tip of the cannula to the vessel. Using a realistic eyeball phantom, we address sclerotomy constraints, eye movement, and non-planar retina. Preliminary results indicate a handheld micromanipulator aided by visual control is a promising solution to retinal vessel occlusion. PMID:24649479

Segmentation of retinal blood vessels using artificial neural networks for early detection of diabetic retinopathy

NASA Astrophysics Data System (ADS)

Mann, Kulwinder S.; Kaur, Sukhpreet

2017-06-01

There are various eye diseases in the patients suffering from the diabetes which includes Diabetic Retinopathy, Glaucoma, Hypertension etc. These all are the most common sight threatening eye diseases due to the changes in the blood vessel structure. The proposed method using supervised methods concluded that the segmentation of the retinal blood vessels can be performed accurately using neural networks training. It uses features which include Gray level features; Moment Invariant based features, Gabor filtering, Intensity feature, Vesselness feature for feature vector computation. Then the feature vector is calculated using only the prominent features.

Estimation of retinal vessel caliber using model fitting and random forests

NASA Astrophysics Data System (ADS)

Araújo, Teresa; Mendonça, Ana Maria; Campilho, Aurélio

2017-03-01

Retinal vessel caliber changes are associated with several major diseases, such as diabetes and hypertension. These caliber changes can be evaluated using eye fundus images. However, the clinical assessment is tiresome and prone to errors, motivating the development of automatic methods. An automatic method based on vessel crosssection intensity profile model fitting for the estimation of vessel caliber in retinal images is herein proposed. First, vessels are segmented from the image, vessel centerlines are detected and individual segments are extracted and smoothed. Intensity profiles are extracted perpendicularly to the vessel, and the profile lengths are determined. Then, model fitting is applied to the smoothed profiles. A novel parametric model (DoG-L7) is used, consisting on a Difference-of-Gaussians multiplied by a line which is able to describe profile asymmetry. Finally, the parameters of the best-fit model are used for determining the vessel width through regression using ensembles of bagged regression trees with random sampling of the predictors (random forests). The method is evaluated on the REVIEW public dataset. A precision close to the observers is achieved, outperforming other state-of-the-art methods. The method is robust and reliable for width estimation in images with pathologies and artifacts, with performance independent of the range of diameters.

Radiation-induced ocular injury in the dog: a histological study.

PubMed

Ching, S V; Gillette, S M; Powers, B E; Roberts, S M; Gillette, E L; Withrow, S J

1990-08-01

Radiation-induced ocular injury secondary to treatment of nasal cancer occurs in humans and animals. Dogs with nasal carcinomas were randomized to receive 36 to 67.5 Gy in fractionated doses given in 4 weeks using a 6 MV linear accelerator. Ophthalmic examinations were performed according to a predetermined protocol and eyes were removed for histologic examination when dogs were euthanatized. The eye in the radiation field exhibited greater injury than the contralateral eye with nasal areas of the globe having more severe lesions than temporal areas. Lesions occurred in all dogs and at all doses. At 1 month or less postirradiation treatment, all dogs had blepharitis, keratoconjunctivitis and corneal epithelial atrophy. Surface lesions persisted in all eyes, becoming less severe and more chronic with time. At 3-6 months postirradiation treatment, degenerative angiopathy of retinal vessels appeared with multifocal retinal hemorrhage and mild diffuse retinal degeneration which affected outer layers first and progressed inwardly with time. At 6 months postirradiation treatment, there were cataracts, fibrosis of retinal vessel walls with loss of vascular smooth muscle, retinal hemorrhage, and mild to moderate retinal degeneration. At 1 year postirradiation treatment, retinal vessels remained sclerotic, retinal hemorrhage was less frequent, and there was moderate retinal degeneration with swelling and loss of ganglion cells. By 2 years or more postirradiation treatment, optic nerve axonal degeneration secondary to retinal changes had appeared. Tapetal and choroidal atrophy were inconsistently seen. Thus, ocular lesions at the doses received developed along a relatively predictable time course and recovery was not seen. Structures of the canine eye appear sufficiently sensitive that even relatively low total doses given in small doses per fraction cause significant long-term injury.

[The clinical investigation of peripheral retinal changes of anterior uveitis].

PubMed

Guo, Chunying; Qiao, Lijun; Yang, Liu

2015-10-01

To observe the peripheral retinal changes of anterior uveitis patients using ultra-wide field fluorescein angiography. Retrospective case series study. Thirty-three eyes of 20 patients diagnosed as anterior uveitis from September to November 2013 in the ophthalmic clinic of Peking University First Hospital was included. All the patients underwent routine ocular examination, followed by ultra-wide field Fluorescein. There were 13 male patients and 7 female patients, aged 23-66, an average of 46 years old. The anterior uveitis recurrent in both eyes in 13 patients and only one eye in 7 patients. Uveitis duration ranging from months to 30 years. Twenty eyes were at the active stage of the anterior uveitis while 13 eyes in the quiescent stage. Peripheral retinal vessels leakage was detected in 57.6% (19/33) of the eyes, among which in eyes with active disease the rate of peripheral retinal vessels leakage was 75% (15/20), and in eyes with quiescent disease the rate was 30.8% (4/13). Optic disk hyperfluorescence was found in 6 of 20 eyes with active disease. Cystoid macular edema was found in 4 eyes. In addition, peripheral retinal hyperfluorescence dot and zone were detected in 2 eyes. Peripheral retinal vessels were detected to have inflammative leakage in patients of anterior uveitis by ultra-wide field fluorescein agiography. Peripheral retinal inflammation may still exist even in the quiescent stage of the anterior uveitis.

Retinal oximetry measures systemic hypoxia in central nervous system vessels in chronic obstructive pulmonary disease

PubMed Central

Bragason, David; Hardarson, Sveinn Hakon; Vacchiano, Charles; Gislason, Thorarinn; Kristjansdottir, Jona Valgerdur; Kristjansdottir, Gudrun; Stefánsson, Einar

2017-01-01

Background Determination of the blood oxyhemoglobin saturation in the retinal vessels of the eye can be achieved through spectrophotometric retinal oximetry which provides access to the state of oxyhemoglobin saturation in the central nervous system circulation. The purpose of this study was to test the capability of the Oxymap T1 oximeter to detect systemic hypoxemia and the effect of supplemental oxygen on retinal vessel oxyhemoglobin saturation. Methods Oxygen saturation of hemoglobin in retinal arterioles and venules was measured in 11 subjects with severe chronic obstructive pulmonary disease (COPD) on long term oxygen therapy. Measurements were made with and without their daily supplemental oxygen. Eleven healthy age and gender matched subjects were measured during ambient air breathing for comparison of oxyhemoglobin saturation in retinal arterioles and venules. Retinal arteriolar oxyhemoglobin saturation in COPD subjects inspiring ambient air was compared with finger pulse oximetry and blood samples from radial artery. Results COPD subjects had significantly lower oxyhemoglobin saturation during ambient air breathing than healthy controls in both retinal arterioles (87.2%±4.9% vs. 93.4%±4.3%, p = 0.02; n = 11) and venules (45.0%±10.3% vs. 55.2%±5.5%, p = 0.01). Administration of their prescribed supplemental oxygen increased oxyhemoglobin saturation in retinal arterioles (87.2%±4.9% to 89.5%±6.0%, p = 0.02) but not in venules (45.0%±10.3% to 46.7%±12.8%, p = 0.3). Retinal oximetry values were slightly lower than radial artery blood values (mean percentage points difference = -5.0±5.4, 95% CI: -15.68 to 5.67) and finger pulse oximetry values (-3.1±5.5, 95% CI: -14.05 to 7.84). Conclusions The noninvasive Oxymap T1 retinal oximetry detects hypoxemia in central nervous system vessels in patients with severe COPD compared with healthy controls. The instrument is sensitive to changes in oxygen breathing but displays slightly lower measures than finger pulse oximetry or radial artery measures. With further technological improvement, retinal oximetry may offer noninvasive “on-line” measurement of oxygen levels in central circulation in general anesthesia and critically ill patients. PMID:28328974

Estimation of safe exposure time from an ophthalmic operating microscope with regard to ultraviolet radiation and blue-light hazards to the eye

NASA Astrophysics Data System (ADS)

Michael, Ralph; Wegener, Alfred

2004-08-01

Hazards from the optical radiation of an operating microscope that cause damage at the corneal, lenticular, and retinal levels were investigated; we considered, in particular, ultraviolet radiation (UVR) and blue light. The spectral irradiance from a Zeiss operation microscope OPMI VISU 200 was measured in the corneal plane between 300 and 1100 nm. Effective irradiance and radiance were calculated with relative spectral effectiveness data from the American Conference for Governmental and Industrial Hygienists. Safe exposure time to avoid UVR injury to the lens and cornea was found to be 2 h without a filter, 4 h with a UVR filter, 200 h with a yellow filter, and 400 h with a filter combination. Safe exposure time to avoid retinal photochemical injury was found to be 3 min without a filter and with a UVR filter, 10 min with a yellow filter, and 49 min with a filter combination. The effective radiance limit for retinal thermal injury was not exceeded. The hazard due to the UVR component from the operating microscope is not critical, and operation time can be safely prolonged with the use of appropriate filters. The retinal photochemical hazard appears critical without appropriate filters, permitting only some minutes of safe exposure time. The calculated safe exposure times are for worst-case conditions and maximal light output and include a safety factor.

Estimation of safe exposure time from an ophthalmic operating microscope with regard to ultraviolet radiation and blue-light hazards to the eye.

PubMed

Michael, Ralph; Wegener, Alfred

2004-08-01

Hazards from the optical radiation of an operating microscope that cause damage at the corneal, lenticular, and retinal levels were investigated; we considered, in particular, ultraviolet radiation (UVR) and blue light. The spectral irradiance from a Zeiss operation microscope OPMI VISU 200 was measured in the corneal plane between 300 and 1100 nm. Effective irradiance and radiance were calculated with relative spectral effectiveness data from the American Conference for Governmental and Industrial Hygienists. Safe exposure time to avoid UVR injury to the lens and cornea was found to be 2 h without a filter, 4 h with a UVR filter, 200 a yellow filter, and 400 h with a filter combination. Safe exposure time to avoid retinal photochemical injury was found to be 3 min without a filter and with a UVR filter, 10 min with a yellow filter, and 49 min with a filter combination. The effective radiance limit for retinal thermal injury was not exceeded. The hazard due to the UVR component from the operating microscope is not critical, and operation time can be safely prolonged with the use of appropriate filters. The retinal photochemical hazard appears critical without appropriate filters, permitting only some minutes of safe exposure time. The calculated safe exposure times are for worst-case conditions and maximal light output and include a safety factor.

Automated identification of retinal vessels using a multiscale directional contrast quantification (MDCQ) strategy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhen, Yi; Zhang, Xinyuan; Wang, Ningli, E-mail: wningli@vip.163.com, E-mail: puj@upmc.edu

2014-09-15

Purpose: A novel algorithm is presented to automatically identify the retinal vessels depicted in color fundus photographs. Methods: The proposed algorithm quantifies the contrast of each pixel in retinal images at multiple scales and fuses the resulting consequent contrast images in a progressive manner by leveraging their spatial difference and continuity. The multiscale strategy is to deal with the variety of retinal vessels in width, intensity, resolution, and orientation; and the progressive fusion is to combine consequent images and meanwhile avoid a sudden fusion of image noise and/or artifacts in space. To quantitatively assess the performance of the algorithm, wemore » tested it on three publicly available databases, namely, DRIVE, STARE, and HRF. The agreement between the computer results and the manual delineation in these databases were quantified by computing their overlapping in both area and length (centerline). The measures include sensitivity, specificity, and accuracy. Results: For the DRIVE database, the sensitivities in identifying vessels in area and length were around 90% and 70%, respectively, the accuracy in pixel classification was around 99%, and the precisions in terms of both area and length were around 94%. For the STARE database, the sensitivities in identifying vessels were around 90% in area and 70% in length, and the accuracy in pixel classification was around 97%. For the HRF database, the sensitivities in identifying vessels were around 92% in area and 83% in length for the healthy subgroup, around 92% in area and 75% in length for the glaucomatous subgroup, around 91% in area and 73% in length for the diabetic retinopathy subgroup. For all three subgroups, the accuracy was around 98%. Conclusions: The experimental results demonstrate that the developed algorithm is capable of identifying retinal vessels depicted in color fundus photographs in a relatively reliable manner.« less

Automated measurement of retinal blood vessel tortuosity

NASA Astrophysics Data System (ADS)

Joshi, Vinayak; Reinhardt, Joseph M.; Abramoff, Michael D.

2010-03-01

Abnormalities in the vascular pattern of the retina are associated with retinal diseases and are also risk factors for systemic diseases, especially cardiovascular diseases. The three-dimensional retinal vascular pattern is mostly formed congenitally, but is then modified over life, in response to aging, vessel wall dystrophies and long term changes in blood flow and pressure. A characteristic of the vascular pattern that is appreciated by clinicians is vascular tortuosity, i.e. how curved or kinked a blood vessel, either vein or artery, appears along its course. We developed a new quantitative metric for vascular tortuosity, based on the vessel's angle of curvature, length of the curved vessel over its chord length (arc to chord ratio), number of curvature sign changes, and combined these into a unidimensional metric, Tortuosity Index (TI). In comparison to other published methods this method can estimate appropriate TI for vessels with constant curvature sign and vessels with equal arc to chord ratios, as well. We applied this method to a dataset of 15 digital fundus images of 8 patients with Facioscapulohumeral muscular dystrophy (FSHD), and to the other publically available dataset of 60 fundus images of normal cases and patients with hypertensive retinopathy, of which the arterial and venous tortuosities have also been graded by masked experts (ophthalmologists). The method produced exactly the same rank-ordered list of vessel tortuosity (TI) values as obtained by averaging the tortuosity grading given by 3 ophthalmologists for FSHD dataset and a list of TI values with high ranking correlation with the ophthalmologist's grading for the other dataset. Our results show that TI has potential to detect and evaluate abnormal retinal vascular structure in early diagnosis and prognosis of retinopathies.

Automatic classification of retinal vessels into arteries and veins

NASA Astrophysics Data System (ADS)

Niemeijer, Meindert; van Ginneken, Bram; Abràmoff, Michael D.

2009-02-01

Separating the retinal vascular tree into arteries and veins is important for quantifying vessel changes that preferentially affect either the veins or the arteries. For example the ratio of arterial to venous diameter, the retinal a/v ratio, is well established to be predictive of stroke and other cardiovascular events in adults, as well as the staging of retinopathy of prematurity in premature infants. This work presents a supervised, automatic method that can determine whether a vessel is an artery or a vein based on intensity and derivative information. After thinning of the vessel segmentation, vessel crossing and bifurcation points are removed leaving a set of vessel segments containing centerline pixels. A set of features is extracted from each centerline pixel and using these each is assigned a soft label indicating the likelihood that it is part of a vein. As all centerline pixels in a connected segment should be the same type we average the soft labels and assign this average label to each centerline pixel in the segment. We train and test the algorithm using the data (40 color fundus photographs) from the DRIVE database1 with an enhanced reference standard. In the enhanced reference standard a fellowship trained retinal specialist (MDA) labeled all vessels for which it was possible to visually determine whether it was a vein or an artery. After applying the proposed method to the 20 images of the DRIVE test set we obtained an area under the receiver operator characteristic (ROC) curve of 0.88 for correctly assigning centerline pixels to either the vein or artery classes.

SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY REVEALS INTERNAL LIMITING MEMBRANE PEELING ALTERS DEEP RETINAL VASCULATURE.

PubMed

Michalewska, Zofia; Nawrocki, Jerzy

2018-04-30

To describe morphology of retinal and choroidal vessels in swept-source optical coherence tomography angiography before and after vitrectomy with the temporal inverted internal limiting membrane (ILM) flap technique for full-thickness macular holes. Prospective, observational study of 36 eyes of 33 patients with full-thickness macular holes swept-source optical coherence tomography angiography was performed in patients before and 1 month after vitrectomy. Vitrectomy with the temporal inverted ILM flap technique was performed. In this method, ILM is peeled only at one side of the fovea. An ILM flap is created to cover the macular hole. Comparison of retina vasculature in the areas of ILM peeling vs. no ILM peeling at 1 and 3 months after successful vitrectomy was performed. The study demonstrated lower density of vessels in the deep retinal plexus in the area where ILM was peeled as compared to the rest of the fovea. Visual acuity and central retinal thickness 1 month after surgery correlates with fovea avascular zone diameter in deep retinal layers at the same time point (P = 0.001). This study confirmed that ILM peeling might alter blood flow in deep retinal vessels below the peeling area in the early postoperative period. The area of the fovea avascular zone corresponds to functional results at the same time point.

Automatic retinal blood flow calculation using spectral domain optical coherence tomography

NASA Astrophysics Data System (ADS)

Wehbe, Hassan; Ruggeri, Marco; Jiao, Shuliang; Gregori, Giovanni; Puliafito, Carmen A.

2008-02-01

Optical Doppler tomography (ODT) is a branch of optical coherence tomography (OCT) that can measure the speed of a blood flow by measuring the Doppler shift impinged on the probing sample light by the moving blood cells. However, the measured speed of blood flow is a function of the Doppler angle, which needs to be determined in order to calculate the absolute velocity of the blood flow inside a vessel. We developed a technique that can extract the Doppler angle from the 3D data measured with spectral-domain OCT, which needs to extract the lateral and depth coordinates of a vessel in each measured ODT and OCT image. The lateral coordinates and the diameter of a blood vessel were first extracted in each OCT structural image by using the technique of blood vessel shadowgram, a technique first developed by us for enhancing the retinal blood vessel contrast in the en face view of the 3D OCT. The depth coordinate of a vessel was then determined by using a circular averaging filter moving in the depth direction along the axis passing through the vessel center in the ODT image. The Doppler angle was then calculated from the extracted coordinates of the blood vessel. The technique was applied in blood flow measurements in retinal blood vessels, which has potential impact on the study and diagnosis of blinding diseases like glaucoma and diabetic retinopathy.

Combined Central Retinal Vein and Branch Retinal Artery Occlusion Post Intense Physical Activity.

PubMed

Coca, Mircea; Tecle, Nahom; Amde, Wendewessen; Mehta, Ankur

2017-08-23

We report a case of combined central retinal vein occlusion and branch retinal artery occlusion. A previously healthy 47-year-old male presented with decreased vision in the right eye after completing a half marathon. A fundus exam and retinal imaging revealed a combined central retinal vein and branch retinal artery occlusion. In the present report, we review the literature and discuss the possible mechanisms behind combined retinal vessel occlusions. To our knowledge, this is the first reported case of combined central retinal vein occlusion and branch retinal artery occlusion following intense exercise.

Combined Central Retinal Vein and Branch Retinal Artery Occlusion Post Intense Physical Activity

PubMed Central

Tecle, Nahom; Amde, Wendewessen; Mehta, Ankur

2017-01-01

We report a case of combined central retinal vein occlusion and branch retinal artery occlusion. A previously healthy 47-year-old male presented with decreased vision in the right eye after completing a half marathon. A fundus exam and retinal imaging revealed a combined central retinal vein and branch retinal artery occlusion. In the present report, we review the literature and discuss the possible mechanisms behind combined retinal vessel occlusions. To our knowledge, this is the first reported case of combined central retinal vein occlusion and branch retinal artery occlusion following intense exercise. PMID:29067224

Dependence of diameters and oxygen saturation of retinal vessels on visual field damage and age in primary open-angle glaucoma.

PubMed

Ramm, Lisa; Jentsch, Susanne; Peters, Sven; Sauer, Lydia; Augsten, Regine; Hammer, Martin

2016-05-01

To investigate the interrelationship between the oxygen supply of the retina and its regulation with the severity of primary open-angle glaucoma (POAG). Central retinal artery (CRAE) and vein (CRVE) diameters and oxygen saturation of peripapillary retinal vessels in 41 patients suffering from POAG (64.1 ± 12.9 years) and 40 healthy volunteers (63.6 ± 14.1 years) were measured using the retinal vessel analyzer. All measures were taken before and during flicker light stimulation. The mean retinal nerve fiber layer thickness (RNFLT) was determined by OCT and the visual field mean defect (MD) was identified using perimetry. In glaucoma patients, CRAE (r = -0.48 p = 0.002) and CRVE (r = -0.394 p = 0.014) at baseline were inversely related to MD, while arterial and venous oxygen saturation showed no significant dependence on the severity of the damage. However, the flicker light-induced change in arterio-venous difference in oxygen saturation was correlated with the MD (r = 0.358 p = 0.027). The diameters of arteries and veins at baseline decreased with reduction of the mean RNFLT (arteries: r = 0.718 p < 0.001; veins: r = 0.685 p < 0.001). Vessel diameters showed a strong correlation with RNFLT and MD. This, as well as the reduction of stimulation-induced change in arterio-venous oxygen saturation difference with visual field loss, may be explained by a reduction of the retinal metabolic demand with progressive loss of neuronal tissue in glaucoma. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

An Unsupervised Approach for Extraction of Blood Vessels from Fundus Images.

PubMed

Dash, Jyotiprava; Bhoi, Nilamani

2018-04-26

Pathological disorders may happen due to small changes in retinal blood vessels which may later turn into blindness. Hence, the accurate segmentation of blood vessels is becoming a challenging task for pathological analysis. This paper offers an unsupervised recursive method for extraction of blood vessels from ophthalmoscope images. First, a vessel-enhanced image is generated with the help of gamma correction and contrast-limited adaptive histogram equalization (CLAHE). Next, the vessels are extracted iteratively by applying an adaptive thresholding technique. At last, a final vessel segmented image is produced by applying a morphological cleaning operation. Evaluations are accompanied on the publicly available digital retinal images for vessel extraction (DRIVE) and Child Heart And Health Study in England (CHASE_DB1) databases using nine different measurements. The proposed method achieves average accuracies of 0.957 and 0.952 on DRIVE and CHASE_DB1 databases respectively.

Very low risk of light-induced retinal damage during Boston keratoprosthesis surgery: a rabbit study.

PubMed

Salvador-Culla, Borja; Behlau, Irmgard; Sayegh, Rony R; Stacy, Rebecca C; Dohlman, Claes H; Delori, François

2014-02-01

The aim of this study was to assess the possibility of light damage to the retina by a surgical microscope during implantation of a Boston Keratoprosthesis (B-KPro) in rabbits. The retinal irradiance from a Zeiss OPMI Lumera S7 operating microscope was measured at the working distance (16.5 cm). Light transmittance through an isolated B-KPro was measured. A B-KPro was implanted into 1 eye of 12 rabbits with the optic covered during the procedure. The operated eyes were then continuously exposed to a fixed light intensity under the microscope for 1 hour. Fluorescein angiography was carried out on days 2 and 9 postsurgery, after which the animals were euthanized. Further, we compared the potential of these retinal exposures to well-accepted light safety guidelines applicable to humans. Light transmittance of B-KPro revealed a blockage of short wavelengths (<390 nm) and of long wavelengths (1660-1750 nm) of light. In addition, the surgical microscope filtered a part of the blue, ultraviolet, and infrared wavelengths. Neither fluorescein angiography nor a histological examination showed any morphological retinal changes in our rabbits. Moreover, the retinal exposures were well below the safety limits. Modern surgical microscopes have filters incorporated in them that block the most damaging wavelengths of light. The B-KPro is made of 100% poly(methyl methacrylate), which makes it in itself a blocker of short wavelengths of light. No damage could be demonstrated in the animal study, and the retinal exposures were well below the safety limits. Together, these results suggest that light exposures during B-KPro surgery present a low risk of photochemical damage to the retina.

Assessment of the posterior segment of the cat eye by optical coherence tomography (OCT).

PubMed

Gekeler, Florian; Gmeiner, Helmut; Völker, Michael; Sachs, Helmut; Messias, Andre; Eule, Corinna; Bartz-Schmidt, Karl Ulrich; Zrenner, Eberhart; Shinoda, Kei

2007-01-01

To assess the feasibility of optical coherence tomography (OCT) for examining the cat ocular fundus, to provide normative data on retinal thickness in different fundus regions, and to demonstrate selected surgically induced vitreoretinal pathologies in the cat. Forty-five eyes of 28 healthy domestic cats and two eyes of domestic cats that had undergone subretinal implantation surgery for a visual prosthesis were examined. An optical coherence tomograph (Zeiss-Humphrey) was used to examine the anesthetized animals. At least five vertical and five horizontal scans in regular distribution were recorded for each cat including (1) the peripapillary region, (2) the area centralis, and (3) the peripheral retina. Thickness was measured manually at five locations in each scan. Retinal thickness was compared in the three above-mentioned fundus regions, between eyes and between vertical and horizontal scans. OCT was additionally performed in animals with retinal detachment and a subretinal visual prosthesis. OCT measurements required only minimal adjustments of human settings and yielded high quality images. In comparison to humans intraretinal layers were more difficult to differentiate. Retinal thickness was highest in the peripapillary region (245 +/- 21 microm), followed by the peripheral retina (204 +/- 11 microm) and the area centralis (182 +/- 11 microm; all P < 0.0001). There was no statistically significant difference between right and left eye or between vertical and horizontal scans. OCT demonstrated retinal detachment, an iatrogenic break and a subretinal prosthetic device in high detail. Retinal thickness was measurable with high precision; values compare well to older histologic studies. OCT bears significant advantages over histology in enabling one to repeat measurements in living animals and thus allowing longitudinal studies. Various vitreoretinal pathologies common in feline eyes are detectable and quantifiable by OCT.

Scleral electrocautery and its effects on choroid vessels: implications for subretinal fluid drainage during scleral buckling surgery.

PubMed

Roybal, C Nathaniel; Tsui, Irena; Sanfilippo, Christian; Hubschman, Jean-Pierre

2013-01-01

External drainage of subretinal fluid as part of a scleral buckling procedure rapidly restores the retinal pigment epithelium-neural retina interface in rhegmatogenous retinal detachments but carries the inherent risk of subretinal hemorrhage and retinal incarceration. The authors investigated variations to the technique to reduce the chance of subretinal hemorrhage originating from the choroid. A novel method for needle drainage using electrocautery of the sclerochoroidal layers before puncture was employed. The effect of 0% to 50% scleral electrocautery in a porcine model was investigated. A significant decrease in choroidal vessel diameter and choroidal vessel density at 40% electrocautery was demonstrated. Electrocautery without scleral cut-down before external drainage of subretinal fluid likely decreases the chance of subretinal hemorrhage by decreasing choroidal vascularity. Copyright 2013, SLACK Incorporated.

Eye shape using partial coherence interferometry, autorefraction, and SD-OCT.

PubMed

Clark, Christopher A; Elsner, Ann E; Konynenbelt, Benjamin J

2015-01-01

Peripheral refraction and retinal shape may influence refractive development. Peripheral refraction has been shown to have a high degree of variability and can take considerable time to perform. Spectral domain optical coherence tomography (SD-OCT) and peripheral axial length measures may be more reliable, assuming that the retinal position is more important than the peripheral optics of the lens/cornea. Seventy-nine subjects' right eyes were imaged for this study (age range, 22 to 34 years; refractive error, -10 to +5.00). Thirty-degree SD-OCT (Spectralis, Heidelberg Engineering, Heidelberg, Germany) images were collected in a radial pattern along with peripheral refraction with an autorefractor (Shin-Nippon Autorefractor) and peripheral axial length measurements with partial coherence interferometry (IOLMaster, Zeiss). Statistics were performed using repeated-measures analysis of variance in SPSS (IBM, Armonk, NY), Bland-Altman analyses, and regression. All measures were converted to diopters to allow direct comparison. Spectral domain OCT showed a retinal shape with an increased curvature for myopes compared with emmetropes/hyperopes. This retinal shape change became significant around 5 degrees. The SD-OCT analysis for retinal shape provides a resolution of 0.026 diopters, which is about 10 times more accurate than using autorefraction (AR) or clinical refractive techniques. Bland-Altman analyses suggest that retinal shape measured by SD-OCT and the partial coherence interferometry method were more consistent with one another than either was with AR. With more accurate measures of retinal shape using SD-OCT, consistent differences between emmetropes/hyperopes and myopes were found nearer to the fovea than previously reported. Retinal shape may be influenced by central refractive error, and not merely peripheral optics. Partial coherence interferometry and SD-OCT appear to be more accurate than AR, which may be influenced by other factors such as fixation and accommodation. Autorefraction does measure the optics directly, which may be a strength of that method.

Automated retinal vessel type classification in color fundus images

NASA Astrophysics Data System (ADS)

Yu, H.; Barriga, S.; Agurto, C.; Nemeth, S.; Bauman, W.; Soliz, P.

2013-02-01

Automated retinal vessel type classification is an essential first step toward machine-based quantitative measurement of various vessel topological parameters and identifying vessel abnormalities and alternations in cardiovascular disease risk analysis. This paper presents a new and accurate automatic artery and vein classification method developed for arteriolar-to-venular width ratio (AVR) and artery and vein tortuosity measurements in regions of interest (ROI) of 1.5 and 2.5 optic disc diameters from the disc center, respectively. This method includes illumination normalization, automatic optic disc detection and retinal vessel segmentation, feature extraction, and a partial least squares (PLS) classification. Normalized multi-color information, color variation, and multi-scale morphological features are extracted on each vessel segment. We trained the algorithm on a set of 51 color fundus images using manually marked arteries and veins. We tested the proposed method in a previously unseen test data set consisting of 42 images. We obtained an area under the ROC curve (AUC) of 93.7% in the ROI of AVR measurement and 91.5% of AUC in the ROI of tortuosity measurement. The proposed AV classification method has the potential to assist automatic cardiovascular disease early detection and risk analysis.

[Retinal vessels before and after photocoagulation in diabetic retinopathy. Determining the diameter using digitized color fundus slides].

PubMed

Remky, A; Arend, O; Beausencourt, E; Elsner, A E; Bertram, B

1996-01-01

Retinal vessel diameter is an important parameter in blood flow analysis. Despite modern digital image technology, most clinical studies investigate diameters subjectively using projected fundus slides or negatives. In the present study we used a technique to examine vessel diameters by digital image analysis of color fundus slides. We investigated in a retrospective manner diameter changes in twenty diabetic patients before and after panretinal laser coagulation. Color fundus slides were digitized by a new high resolution scanning device. The resulting images consisted in three channels (red, green, blue). Since vessel contrast was the highest in the green channel, we assessed grey value profiles perpendicular to the vessels in the green channel. Diameters were measured at the half-height of the profile. After panretinal laser coagulation, average venous diameter was decreased, whereas arterial diameter remained unchanged. There was no significant relation between the diameter change and the number of laser burns or the presence of neovascularization. Splitting digitized images into color planes enables objective measurements of retinal diameters in conventional color slides.

Ischemia-induced spreading depolarization in the retina

PubMed Central

Srienc, Anja I; Biesecker, Kyle R; Shimoda, Angela M; Kur, Joanna

2016-01-01

Cortical spreading depolarization is a metabolically costly phenomenon that affects the brain in both health and disease. Following severe stroke, subarachnoid hemorrhage, or traumatic brain injury, cortical spreading depolarization exacerbates tissue damage and enlarges infarct volumes. It is not known, however, whether spreading depolarization also occurs in the retina in vivo. We report now that spreading depolarization episodes are generated in the in vivo rat retina following retinal vessel occlusion produced by photothrombosis. The properties of retinal spreading depolarization are similar to those of cortical spreading depolarization. Retinal spreading depolarization waves propagate at a velocity of 3.0 ± 0.1 mm/min and are associated with a negative shift in direct current potential, a transient cessation of neuronal spiking, arteriole constriction, and a decrease in tissue O2 tension. The frequency of retinal spreading depolarization generation in vivo is reduced by administration of the NMDA antagonist MK-801 and the 5-HT(1D) agonist sumatriptan. Branch retinal vein occlusion is a leading cause of vision loss from vascular disease. Our results suggest that retinal spreading depolarization could contribute to retinal damage in acute retinal ischemia and demonstrate that pharmacological agents can reduce retinal spreading depolarization frequency after retinal vessel occlusion. Blocking retinal spreading depolarization generation may represent a therapeutic strategy for preserving vision in branch retinal vein occlusion patients. PMID:27389181

Assessment of capillary dropout in the superficial retinal capillary plexus by optical coherence tomography angiography in the early stage of diabetic retinopathy.

PubMed

Shen, Ceying; Yan, Shu; Du, Min; Zhao, Hong; Shao, Ling; Hu, Yibo

2018-05-08

To assess capillary dropout in the superficial retinal capillary plexus (SCP) by optical coherence tomography angiography (OCTA) in the early stage of diabetic retinopathy (DR). This study was a cross-sectional observational study. Patients that underwent OCTA examinations in our hospital between November 2015 and May 2016 were included in the study. The subjects were divided into two groups: A) normal controls (41 eyes of 41 subjects) and B) the DR patients (49 eyes of 49 patients with mild non-proliferative DR (NPDR)). The retinal thickness and SCP vessel density were analyzed using built-in software in nine sections of the macular area; whole scan area; fovea; parafovea; and sub-sections of the parafovea, superior-hemi, inferior-hemi, temporal, superior, nasal, and inferior. The correlation between vessel density and retinal thickness was also analyzed. The SCP density was significantly lower (P < 0.05) in mild NPDR patients than in normal controls in all areas, with the exception of the fovea (P > 0.05). In the parafovea, superior-hemi, inferior-hemi, temporal, and nasal sectors of group B, the SCP density was negatively correlated with the corresponding retinal thickness (P < 0.05). Specifically, as the SCP density decreased, retinal thickness increased. In the early stage of NPDR, retinal capillary dropout and retinal thickness changes can be clearly captured and analyzed by OCTA. The results confirm a negative correlation between vessel density and retinal thickness in diabetic patients. This noninvasive technique could be applied for DR detection and monitoring. Further study with a larger sample size is warranted.

The Comparison of Regional RNFL and Fundus Vasculature by OCTA in Chinese Myopia Population.

PubMed

Li, Yuanjun; Miara, Hamza; Ouyang, Pingbo; Jiang, Bing

2018-01-01

To determine the correlations between peripapillary vessel density, retinal nerve fibre layer (RNFL) thickness, and myopic indices at retina quadrants with optical coherence tomography angiography (OCTA) in Chinese. Fifty-six subjects with a mean spherical equivalent (MSE) of -3.63 ± 0.29 D were included. Peripapillary RNFL thickness and retinal vessel density in four sectors (superior, nasal, inferior, and temporal quadrants) were determined by OCTA, and correlations of the main outcomes were analyzed. Negative correlations were found between the peripapillary RNFL thickness and axial length (AL) at superior ( r = -0.335, P = 0.001) and inferior ( r = -0.551, P < 0.001) quadrants. There was a significant positive correlation with spherical equivalent (SE) at the corresponding quadrants as well as at the nasal quadrant ( r = 0.339, P = 0.001; r = 0.379, P < 0.001; and r = 0.209, P = 0.039, resp.). Peripapillary retinal vessel density was also negatively correlated with AL at the nasal quadrant ( r = -0.392, P < 0.001), and only at the nasal quadrant, there was a positive correlation between the peripapillary vessel density and SE ( r = 0.319, P = 0.001). The degree of myopia and elongation of AL were negatively correlated with peripapillary RNFL thickness at superior and inferior quadrants and with peripapillary retinal vessel density at the nasal quadrant.

The Comparison of Regional RNFL and Fundus Vasculature by OCTA in Chinese Myopia Population

PubMed Central

2018-01-01

Purpose To determine the correlations between peripapillary vessel density, retinal nerve fibre layer (RNFL) thickness, and myopic indices at retina quadrants with optical coherence tomography angiography (OCTA) in Chinese. Methods Fifty-six subjects with a mean spherical equivalent (MSE) of −3.63 ± 0.29 D were included. Peripapillary RNFL thickness and retinal vessel density in four sectors (superior, nasal, inferior, and temporal quadrants) were determined by OCTA, and correlations of the main outcomes were analyzed. Results Negative correlations were found between the peripapillary RNFL thickness and axial length (AL) at superior (r = −0.335, P = 0.001) and inferior (r = −0.551, P < 0.001) quadrants. There was a significant positive correlation with spherical equivalent (SE) at the corresponding quadrants as well as at the nasal quadrant (r = 0.339, P = 0.001; r = 0.379, P < 0.001; and r = 0.209, P = 0.039, resp.). Peripapillary retinal vessel density was also negatively correlated with AL at the nasal quadrant (r = −0.392, P < 0.001), and only at the nasal quadrant, there was a positive correlation between the peripapillary vessel density and SE (r = 0.319, P = 0.001). Conclusions The degree of myopia and elongation of AL were negatively correlated with peripapillary RNFL thickness at superior and inferior quadrants and with peripapillary retinal vessel density at the nasal quadrant. PMID:29651341

Retinal vascular imaging technology to monitor disease severity and complications in type 1 diabetes mellitus: A systematic review.

PubMed

Kee, Ae Ra; Wong, Tien Yin; Li, Ling-Jun

2017-02-01

Type 1 diabetes mellitus (T1DM) is a major disease affecting a large number of young patients. In the recent years, retinal vascular imaging has provided an objective assessment of vascular health in patients with T1DM. Our study aimed to review the current literature on retinal vascular parameters in young patients with T1DM in order to understand the following: (i) How retinal vessels are affected in T1DM (ii) How such vascular changes can be predictive of future diabetic microvascular complications METHODS: We performed a systematic review and extracted relevant data from 17 articles. We found significant correlations between retinal vessel changes and diabetes-related risk factors (eg, hypertension, hyperlipidemia, and obesity), diabetes-related features (eg, diabetes duration and glycemic control), and diabetes-related microvascular complications (eg, diabetic retinopathy, nephropathy, and neuropathy). Our findings suggest that retinal microvasculature is associated with both disease severity and complications in young patients with T1DM. © 2016 John Wiley & Sons Ltd.

Choroidal Thickness, Photoreceptor Thickness, and Retinal Vascular Caliber Alterations in Dark Adaptation.

PubMed

Alagöz, Cengiz; Pekel, Gökhan; Alagöz, Neşe; Sayın, Nihat; Yüksel, Kemal; Yıldırım, Yusuf; Yazıcı, Ahmet Taylan

2016-12-01

Our aim was to evaluate the alterations of subfoveal choroidal thickness (SFCT), photoreceptor layer thickness (PRT), and retinal vessel diameter in the dark and light adaptation. Twenty-four eyes of 24 healthy volunteers (12 males, 12 females) were included in this cross-sectional and observational study. The SFCT, PRT, retinal arteriole, and venule caliber measurements were performed with spectral domain optical coherence tomography in the dark (0.0 cd/m 2 ) and under light (80 cd/m 2 ) adapted conditions. The mean age of the participants was 30.4 ± 4.4 years (range: 22-42). The SFCT increased statistically significantly in dark adaptation (p < 0.001), then returned to baseline values following light adaptation. The PRT, retinal arteriole, and venule caliber measurements were similar in the dark and light (p > 0.05). While SFCT increased, PRT, and retinal vessel diameter did not change following transition from light to dark.

Intraoperative optical coherence tomography assisted analysis of pars Plana vitrectomy for retinal detachment in morning glory syndrome: a case report.

PubMed

Lytvynchuk, Lyubomyr M; Glittenberg, Carl G; Ansari-Shahrezaei, Siamak; Binder, Susanne

2017-08-01

The pathogenesis of non-rhegmatogenous retinal detachment (non-RRD) associated with morning glory syndrome (MGS) is not established, as well as best surgical approach to treat RD. Our purpose was to analyse intraoperative optical coherence tomography data (iOCT) in all steps of pars plana vitrectomy (PPV) for non-RRD in MGS, in order to follow pathophysiological aspects of the disease and to understand the tissues behaviour during surgical workflow. Intraoperative spectral domain optical coherent tomography (iSD-OCT) assisted PPV using Rescan 700 (Carl Zeiss Meditech, Jena, Germany) with epiretinal membrane (ERM) and internal retinal membrane (ILM) peeling, and air endotamponade was performed on the only eye of a 21 years old female with non-RRD associated with MGS. BCVA, pre-, intra- and postoperative OCT were performed along with standard ocular examination. iOCT video and snapshots were analysed intra- and postoperatively using post-processing approach using graphic software. The progression of non-RRD resulted in best corrected visual acuity (BCVA) decrease from 0.8 to 0.2. Triamcinolone enhanced iOCT imaging revealed strong vitreous traction and adhesion above the macula and optic disc. Internal limiting membrane was peeled under iOCT control to prevent the peeling of inner layers of the retinal schisis. No retinal break was detected, and only air endotamponade was performed. The retina reattached during first 4 weeks of follow-up with gradual resolution of intraretinal- and subretinal fluid, and remained stable in 12 months. BCVA improved to 0.8. Based on iSD-OCT findings we assume that non-RRD in this case of MGS is caused primarily by the vitreous traction with further possible formation of the retinal breaks. Retinal reattachment reached only with air endotamponade strongly advocates the tractional component of non-RRD and retinal schisis assotiated with MGS. Early PPV for central non-RRD and retinal schisis with the use of iOCT can be performed in more safe and controlled manner and has to be considered to reduce the risk of retinal break formation and to prevent the central vision loss.

Retinal Oxygen: from animals to humans

PubMed Central

Linsenmeier, Robert A.; Zhang, Hao F.

2017-01-01

This article discusses retinal oxygenation and retinal metabolism by focusing on measurements made with two of the principal methods used to study O2 in the retina: measurements of PO2 with oxygen-sensitive microelectrodes in vivo in animals with a retinal circulation similar to that of humans, and oximetry, which can be used non-invasively in both animals and humans to measure O2 concentration in retinal vessels. Microelectrodes uniquely have high spatial resolution, allowing the mapping of PO2 in detail, and when combined with mathematical models of diffusion and consumption, they provide information about retinal metabolism. Mathematical models, grounded in experiments, can also be used to simulate situations that are not amenable to experimental study. New methods of oximetry, particularly photoacoustic ophthalmoscopy and visible light optical coherence tomography, provide depth-resolved methods that can separate signals from blood vessels and surrounding tissues, and can be combined with blood flow measures to determine metabolic rate. We discuss the effects on retinal oxygenation of illumination, hypoxia and hyperoxia, and describe retinal oxygenation in diabetes, retinal detachment, arterial occlusion, and macular degeneration. We explain how the metabolic measurements obtained from microelectrodes and imaging are different, and how they need to be brought together in the future. Finally, we argue for revisiting the clinical use of hyperoxia in ophthalmology, particularly in retinal arterial occlusions and retinal detachment, based on animal research and diffusion theory. PMID:28109737

The association of socio-economic factors with physical fitness and activity behaviours, spinal posture and retinal vessel parameters in first graders in urban Switzerland.

PubMed

Imhof, Katharina; Faude, Oliver; Donath, Lars; Bean-Eisenhut, Salome; Hanssen, Henner; Zahner, Lukas

2016-01-01

Socio-economic status during childhood has been shown to be a strong predictor of adult health outcome. Therefore, we examined associations of parental educational level, household income and migrant background with physical fitness, spinal flexibility, spinal posture as well as retinal vessel diameters in children of an urban Swiss region. A total of 358 first graders of the Swiss canton Basel-Stadt (age: 7.3, SD: 0.4) were examined. Physical fitness (20 m shuttle run test, 20 m sprint, jumping sidewards and balancing backwards), spinal flexibility and spinal posture (MediMouse®, Idiag, Fehraltdorf, Switzerland) and retinal microcirculation (Static Retinal Vessel Analyzer, Imedos Systems UG, Jena, Germany) were assessed. Parental education, household income, migrant background and activity behaviour were evaluated with a questionnaire. Parental education was associated with child aerobic fitness (P = 0.03) and screen time (P < 0.001). Household income was associated with jumping sidewards (P = 0.009), balancing backwards (P = 0.03) and sports club participation (P = 0.02). Migrant background was associated with BMI (P = 0.001), body fat (P = 0.03), aerobic fitness (P = 0.007), time spent playing outdoors (P < 0.001) and screen time (P < 0.001). For spinal flexibility and retinal vessel diameter, no associations were found (0.06 < P < 0.8). Low parental education, low household income and a migrant background are associated with poor physical fitness, higher BMI and body fat percentage and low-activity behaviour.

[Evaluation of diabetic microangiopathy using optical coherence tomography angiography].

PubMed

Czakó, Cecília; Sándor, Gábor László; Ecsedy, Mónika; Szepessy, Zsuzsanna; Borbándy, Ágnes; Resch, Miklós; Papp, András; Récsán, Zsuzsa; Horváth, Hajnalka; Nagy, Zoltán Zsolt; Kovács, Illés

2018-02-01

Optical coherence tomography angiography is a non-invasive imaging technique that is able to visualize the different retinal vascular layers using motion contrast to detect blood flow without intravenous dye injection. This method might help to assess microangiopathy in diabetic retinopathy during screening and follow-up. To quantify retinal microvasculature alterations in both eyes of diabetic patients in relation to systemic risk factors using optical coherence tomography angiography. Both eyes of 36 diabetic patients and 45 individuals without diabetes were examined. Duration of diabetes, insulin therapy, blood pressure, HbA 1c , dyslipidemia, axial length and the presence of diabetic retinopathy were recorded. Retinal vessel density was measured by optical coherence tomography angiography. The effect of risk factors on vessel density and between-eye asymmetry was assessed using multivariable regression analysis. Vessel density was significantly lower and between-eye difference was significantly higher in diabetic patients compared to controls (p<0.05). Both vessel density and between-eye asymmetry significantly correlated with diabetes duration (p<0.05) after controlling for the effect of risk factors. The between-eye asymmetry in vessel density was significantly higher in patients without clinically detectable diabetic retinopathy compared to control subjects (p<0.001). There is a decrease in retinal vessel density and an increase in between-eye asymmetry in patients with diabetes compared to healthy subjects. By using optical coherence tomography angiography, the detection of these microvascular alterations is possible before clinically detectable diabetic retinopathy and might serve as a useful tool in both screening and timing of treatment. Orv Hetil. 2018; 159(8): 320-326.

Automated segmentation of retinal blood vessels and identification of proliferative diabetic retinopathy

NASA Astrophysics Data System (ADS)

Jelinek, Herbert F.; Cree, Michael J.; Leandro, Jorge J. G.; Soares, João V. B.; Cesar, Roberto M.; Luckie, A.

2007-05-01

Proliferative diabetic retinopathy can lead to blindness. However, early recognition allows appropriate, timely intervention. Fluorescein-labeled retinal blood vessels of 27 digital images were automatically segmented using the Gabor wavelet transform and classified using traditional features such as area, perimeter, and an additional five morphological features based on the derivatives-of-Gaussian wavelet-derived data. Discriminant analysis indicated that traditional features do not detect early proliferative retinopathy. The best single feature for discrimination was the wavelet curvature with an area under the curve (AUC) of 0.76. Linear discriminant analysis with a selection of six features achieved an AUC of 0.90 (0.73-0.97, 95% confidence interval). The wavelet method was able to segment retinal blood vessels and classify the images according to the presence or absence of proliferative retinopathy.

Test-retest reliability of retinal oxygen saturation measurement.

PubMed

O'Connell, Rachael A; Anderson, Andrew J; Hosking, Sarah L; Batcha, Abrez H; Bui, Bang V

2014-06-01

To determine intrasession and intersession repeatability of retinal vessel oxygen saturation from the Oxymap Retinal Oximeter using a whole image-based analysis technique and so determine optimal analysis parameters to reduce variability. Ten fundus oximetry images were acquired through dilated pupils from 18 healthy participants (aged 22 to 38) using the Oxymap Retinal Oximeter T1. A further 10 images were obtained 1 to 2 weeks later from each individual. Analysis was undertaken for subsets of images to determine the number of images needed to return a stable coefficient of variation (CoV). Intrasession and intersession variability were quantified by evaluating the CoV and establishing the 95% limits of agreement using Bland and Altman analysis. Retinal oxygenation was derived from the distribution of oxygenation values from all vessels of a given width in an image or set of images, as described by Paul et al. in 2013. Grouped in 10-μm-wide bins, oxygen saturation varied significantly for both arteries and veins (p < 0.01). Between 110 and 150 μm, arteries had the least variability between individuals, with average CoVs less than 5% whose confidence intervals did not overlap with the greater than 10% average CoVs for veins across the same range. Bland and Altman analysis showed that there was no bias within or between recording sessions and that the 95% limits of agreement were generally lower in arteries. Retinal vessel oxygen saturation measurements show variability within and between clinical sessions when the whole image is used, which we believe more accurately reflects the true variability in Oxymap images than previous studies on select image segments. Averaging data from vessels 100 to 150 μm in width may help to minimize such variability.

Inter-arm Blood Pressure Difference and its Relationship with Retinal Microvascular Calibres in Young Individuals: The African-PREDICT Study.

PubMed

Strauss, Michél; Smith, Wayne; Schutte, Aletta E

2016-08-01

Bilateral systolic blood pressure (SBP) differences > 10mmHg is a common finding in clinical practice. Such BP differences in older individuals are associated with peripheral vascular disease, linked to microvascular dysfunction. Investigating retinal vessel calibres could provide insight into systemic microvascular function and may predict cardiovascular outcomes. Therefore we investigated the link between inter-arm systolic blood pressure differences (IASBPD) and the retinal microvasculature to determine the usefulness of IASBPD as an early marker of microvascular changes. In this cross-sectional study, we used data from 403 apparently healthy participants (20-30 years) (42% men; 49% black) taking part in the African-PREDICT study. Participants underwent retinal vessel imaging, anthropometric measurements and blood sampling. Brachial BP was measured sequentially in both arms to determine the mean IASBPD. Participants were stratified into two groups with an IASBPD < 10mmHg (n=329) and ≥ 10mmHg (n=47), the only difference in characteristics being a higher right arm SBP in the latter group (p=0.005). We found no association between IASBPD and retinal vessel calibres in any group. Less than 2% of the variance in IASBPD was explained by potential risk factors, with only SBP associating independently with IASBPD (β=115; p=0.039). In a young population an increased IASBPD is not related to retinal vessel diameters suggesting that it does not reflect early microvascular alterations. Copyright © 2016 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

Post-hypoxic constriction of retinal arterioles is impaired during nitric oxide and cyclo-oxygenase inhibition and in diabetic patients without retinopathy.

PubMed

Petersen, Line; Bek, Toke

2017-10-01

Occlusion of retinal vessels leads to retinal ischaemia and hypoxia, which induces vasodilatation in adjacent retinal areas in order to normalize retinal oxygenation. Previous studies have shown that NO and COX products are involved in hypoxia-induced dilatation of retinal arterioles in vitro and in vivo, and that this response is disturbed in patients with diabetes mellitus. However, it is unknown to what extent post-hypoxic recovery of the diameter of retinal arterioles depends on NO and COX products in normal persons and in diabetic patients. The Dynamic Vessel Analyzer (DVA) was used to study the post-hypoxic diameter changes of larger retinal vessels in 20 normal persons, 20 diabetic patients without diabetic retinopathy, and in 18 patients with diabetic maculopathy before and after inhibition of the synthesis of nitric oxide and COX products. In normal persons, the arterioles had re-constricted (p > 0.99) 2 minutes after termination of hypoxia in the absence of antagonists, but not after treatment with L-NMMA and diclofenac (p < 0.01 for all comparisons). In diabetic patients without retinopathy, the arterioles showed no diameter changes after termination of hypoxia during any of the interventions. In patients with diabetic maculopathy hypoxia had not dilated retinal arterioles (p > 0.1 for all comparisons) to allow the study of re-constriction. In all groups, the dilatation of venules remained significantly increased during the post-hypoxic observation period, both in the absence and in the presence of L-NMMA and diclofenac.Post-hypoxic constriction of retinal arterioles depends on NO and COX products, and is impaired in diabetic patients before the development of retinopathy. This disturbance may contribute to the development of diabetic retinopathy, and should be the target of future interventional studies aimed at preventing and treating the disease.ClinicalTrials.gov identifier: NCT01689090.

Calcium Dobesilate Inhibits the Alterations in Tight Junction Proteins and Leukocyte Adhesion to Retinal Endothelial Cells Induced by Diabetes

PubMed Central

Leal, Ermelindo C.; Martins, João; Voabil, Paula; Liberal, Joana; Chiavaroli, Carlo; Bauer, Jacques; Cunha-Vaz, José; Ambrósio, António F.

2010-01-01

OBJECTIVE Calcium dobesilate (CaD) has been used in the treatment of diabetic retinopathy in the last decades, but its mechanisms of action are not elucidated. CaD is able to correct the excessive vascular permeability in the retina of diabetic patients and in experimental diabetes. We investigated the molecular and cellular mechanisms underlying the protective effects of CaD against the increase in blood–retinal barrier (BRB) permeability induced by diabetes. RESEARCH DESIGN AND METHODS Wistar rats were divided into three groups: controls, streptozotocin-induced diabetic rats, and diabetic rats treated with CaD. The BRB breakdown was evaluated using Evans blue. The content or distribution of tight junction proteins (occludin, claudin-5, and zonula occluden-1 [ZO-1]), intercellular adhesion molecule-1 (ICAM-1), and p38 mitogen-activated protein kinase (p38 MAPK) was evaluated by Western blotting and immunohistochemistry. Leukocyte adhesion was evaluated in retinal vessels and in vitro. Oxidative stress was evaluated by the detection of oxidized carbonyls and tyrosine nitration. NF-κB activation was measured by enzyme-linked immunosorbent assay. RESULTS Diabetes increased the BRB permeability and retinal thickness. Diabetes also decreased occludin and claudin-5 levels and altered the distribution of ZO-1 and occludin in retinal vessels. These changes were inhibited by CaD treatment. CaD also inhibited the increase in leukocyte adhesion to retinal vessels or endothelial cells and in ICAM-1 levels, induced by diabetes or elevated glucose. Moreover, CaD decreased oxidative stress and p38 MAPK and NF-κB activation caused by diabetes. CONCLUSIONS CaD prevents the BRB breakdown induced by diabetes, by restoring tight junction protein levels and organization and decreasing leukocyte adhesion to retinal vessels. The protective effects of CaD are likely to involve the inhibition of p38 MAPK and NF-κB activation, possibly through the inhibition of oxidative/nitrosative stress. PMID:20627932

Spectral domain optical coherence tomography and fundus autofluorescence findings in cytomegalovirus retinitis in HIV-infected patients.

PubMed

Yashiro, Shigeko; Nishijima, Takeshi; Yamamoto, Yuuka; Sekine, Yumi; Yoshida-Hata, Natsuyo; Iida, Tomohiro; Oka, Shinichi

2018-05-01

To assess the usefulness of spectral domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF) findings in cytomegalovirus (CMV) retinitis. Observational case series. Thirteen eyes of 11 human immunodeficiency virus (HIV)-positive patients with CMV retinitis underwent full ophthalmologic examinations, SD-OCT, and 4 eyes of 4 patients underwent FAF. FAF images included short-wavelength autofluorescence (SW-AF) and near-infrared autofluorescence (IR-AF). CMV retinitis was classified into proposed categories of acute, subacute, remission, and recurrent; the acute stage was further subdivided into initial, early, and late stages. In the initial stage, vertical structural disruption of all retinal layers was observed by SD-OCT, and FAF showed hyperautofluorescence on SW-AF and hypoautofluorescence on IR-AF. In the early stage, SD-OCT showed significant retinal thickening; cells and debris from the retinal surface to the vitreous; enlarged vessels with/without thickened vessel walls; and highly complicated serous retinal detachment. In the late to subacute stage, features observed included rhegmatogenous retinal detachment with shrinking posterior hyaloid membrane and waving from the ellipsoid zone to the retinal pigment epithelium. In remission, FAF findings were hypoautofluorescence on SW-AF and hyperautofluorescence on IR-AF. Although the number of examined eyes was limited, SD-OCT and FAF provide new information in various stages of CMV retinitis in patients with HIV infection that is not obtainable by conventional examination and which may be of great benefit when screening for the initial stage of CMV retinitis.

Automatic and manual segmentation of healthy retinas using high-definition optical coherence tomography.

PubMed

Golbaz, Isabelle; Ahlers, Christian; Goesseringer, Nina; Stock, Geraldine; Geitzenauer, Wolfgang; Prünte, Christian; Schmidt-Erfurth, Ursula Margarethe

2011-03-01

This study compared automatic- and manual segmentation modalities in the retina of healthy eyes using high-definition optical coherence tomography (HD-OCT). Twenty retinas in 20 healthy individuals were examined using an HD-OCT system (Carl Zeiss Meditec, Inc.). Three-dimensional imaging was performed with an axial resolution of 6 μm at a maximum scanning speed of 25,000 A-scans/second. Volumes of 6 × 6 × 2 mm were scanned. Scans were analysed using a matlab-based algorithm and a manual segmentation software system (3D-Doctor). The volume values calculated by the two methods were compared. Statistical analysis revealed a high correlation between automatic and manual modes of segmentation. The automatic mode of measuring retinal volume and the corresponding three-dimensional images provided similar results to the manual segmentation procedure. Both methods were able to visualize retinal and subretinal features accurately. This study compared two methods of assessing retinal volume using HD-OCT scans in healthy retinas. Both methods were able to provide realistic volumetric data when applied to raster scan sets. Manual segmentation methods represent an adequate tool with which to control automated processes and to identify clinically relevant structures, whereas automatic procedures will be needed to obtain data in larger patient populations. © 2009 The Authors. Journal compilation © 2009 Acta Ophthalmol.

Clinical Outcome of Retinal Vasculitis and Predictors for Prognosis of Ischemic Retinal Vasculitis.

PubMed

Sharief, Lazha; Lightman, Sue; Blum-Hareuveni, Tamar; Bar, Asaf; Tomkins-Netzer, Oren

2017-05-01

To determine factors affecting the visual outcome in eyes with retinal vasculitis and the rate of neovascularization relapse in ischemic vasculitis. Retrospective cohort study. We reviewed 1169 uveitis patients from Moorfields Eye Hospital, London, UK. Retinal vasculitis was observed in 236 eyes (121 ischemic, 115 nonischemic) that were compared with a control group (1022 eyes) with no retinal vasculitis. Ultra-widefield fluorescein angiography images were obtained in 63 eyes with ischemic vasculitis to quantify area of nonperfusion measured as ischemic index. The risk of vision loss was significantly more in the retinal vasculitis compared with the non-vasculitis group (hazard ratio [HR] 1.67, 95% confidence interval [CI] 1.24-2.25, P = .001). Retinal vasculitis had twice the risk of macular edema compared to the non-vasculitis group. Macular ischemia increased the risk of vision loss in vasculitis eyes by 4.4 times. The use of systemic prednisolone in eyes with vasculitis was associated with a reduced risk of vision loss (HR 0.36, 95% CI 0.15-0.82, P = .01). Laser photocoagulation was administered in 75 eyes (62.0%), out of which 29 (38.1%) had new vessel relapse and required additional laser treatment. The median ischemic index was 25.8% (interquartile range 10.2%-46%). Ischemia involving ≥2 quadrants was associated with increased risk of new vessel formation (HR 2.7, 95% CI 1.3-5.5, P = .003). Retinal vasculitis is associated with an increased risk of vision loss, mainly secondary to macular ischemia, and has a higher risk of macular edema compared to eyes with no vasculitis. Ischemia involving ≥2 quadrants is a risk factor for new vessel formation. Copyright © 2017 Elsevier Inc. All rights reserved.

Alterations of the tunica vasculosa lentis in the rat model of retinopathy of prematurity.

PubMed

Favazza, Tara L; Tanimoto, Naoyuki; Munro, Robert J; Beck, Susanne C; Garcia Garrido, Marina; Seide, Christina; Sothilingam, Vithiyanjali; Hansen, Ronald M; Fulton, Anne B; Seeliger, Mathias W; Akula, James D

2013-08-01

To study the relationship between retinal and tunica vasculosa lentis (TVL) disease in retinopathy of prematurity (ROP). Although the clinical hallmark of ROP is abnormal retinal blood vessels, the vessels of the anterior segment, including the TVL, are also altered. ROP was induced in Long-Evans pigmented and Sprague Dawley albino rats; room-air-reared (RAR) rats served as controls. Then, fluorescein angiographic images of the TVL and retinal vessels were serially obtained with a scanning laser ophthalmoscope near the height of retinal vascular disease, ~20 days of age, and again at 30 and 64 days of age. Additionally, electroretinograms (ERGs) were obtained prior to the first imaging session. The TVL images were analyzed for percent coverage of the posterior lens. The tortuosity of the retinal arterioles was determined using Retinal Image multiScale Analysis (Gelman et al. in Invest Ophthalmol Vis Sci 46:4734-4738, 2005). In the youngest ROP rats, the TVL was dense, while in RAR rats, it was relatively sparse. By 30 days, the TVL in RAR rats had almost fully regressed, while in ROP rats, it was still pronounced. By the final test age, the TVL had completely regressed in both ROP and RAR rats. In parallel, the tortuous retinal arterioles in ROP rats resolved with increasing age. ERG components indicating postreceptoral dysfunction, the b-wave, and oscillatory potentials were attenuated in ROP rats. These findings underscore the retinal vascular abnormalities and, for the first time, show abnormal anterior segment vasculature in the rat model of ROP. There is delayed regression of the TVL in the rat model of ROP. This demonstrates that ROP is a disease of the whole eye.

Alterations of the Tunica Vasculosa Lentis in the Rat Model of Retinopathy of Prematurity

PubMed Central

Favazza, Tara L; Tanimoto, Naoyuki; Munro, Robert J.; Beck, Susanne C.; Garrido, Marina G.; Seide, Christina; Sothilingam, Vithiyanjali; Hansen, Ronald M.; Fulton, Anne B.; Seeliger, Mathias W.; Akula, James D

2013-01-01

Purpose To study the relation between retinal and tunica vasculosa lentis (TVL) disease in ROP. Although the clinical hallmark of retinopathy of prematurity (ROP) is abnormal retinal blood vessels, the vessels of the anterior segment, including the TVL, are also altered. Methods ROP was induced in Long Evans pigmented and Sprague-Dawley albino rats; room-air-reared (RAR) rats served as controls. Then, fluorescein angiographic images of the TVL and retinal vessels were serially obtained with a scanning laser ophthalmoscope (SLO) near the height of retinal vascular disease, ∼20 days-of-age, and again at 30 and 64 days-of-age. Additionally, electroretinograms (ERGs) were obtained prior to the first imaging session. The TVL images were analyzed for percent coverage of the posterior lens. The tortuosity of the retinal arterioles was determined using Retinal Image multiScale Analysis (RISA; Gelman et al., 2005). Results In the youngest ROP rats, the TVL was dense, while in RAR rats, it was relatively sparse. By 30 days, the TVL in RAR rats had almost fully regressed, while in ROP rats it was still pronounced. By the final test age, the TVL had completely regressed in both ROP and RAR rats. In parallel, the tortuous retinal arterioles in ROP rats resolved with increasing age. ERG components indicating postreceptoral dysfunction, the b-wave and oscillatory potentials (OPs), were attenuated in ROP rats. Conclusions These findings underscore the retinal vascular abnormalities and, for the first time, show abnormal anterior segment vasculature in the rat model of ROP. There is delayed regression of the TVL in the rat model of ROP. This demonstrates that ROP is a disease of the whole eye. PMID:23748796

The relationship between aortic stiffness and changes in retinal microvessels among Asian ischemic stroke patients.

PubMed

De Silva, D A; Woon, F-P; Manzano, J J F; Liu, E Y; Chang, H-M; Chen, C; Wang, J J; Mitchell, P; Kingwell, B A; Cameron, J D; Lindley, R I; Wong, T Y; Wong, M-C

2012-12-01

Large-artery stiffness is a risk factor for stroke, including cerebral small-vessel disease. Retinal microvascular changes are thought to mirror those in cerebral microvessels. We investigated the relationship between aortic stiffness and retinal microvascular changes in Asian ischemic stroke patients. We studied 145 acute ischemic stroke patients in Singapore who had aortic stiffness measurements using carotid-femoral pulse wave velocity (cPWV). Retinal photographs were assessed for retinal microvessel caliber and qualitative signs of focal arteriolar narrowing, arteriovenous nicking and enhanced arteriolar light reflex. Aortic stiffening was associated with retinal arteriolar changes. Retinal arteriolar caliber decreased with increasing cPWV (r=-0.207, P=0.014). After adjusting for age, gender, hypertension, diabetes, mean arterial pressure and small-vessel stroke subtype, patients within the highest cPWV quartile were more likely to have generalized retinal arteriolar narrowing defined as lowest caliber tertile (odds ratio (OR) 6.84, 95% confidence interval (CI) 1.45-32.30), focal arteriolar narrowing (OR 13.85, CI 1.82-105.67), arteriovenous nicking (OR 5.08, CI 1.12-23.00) and enhanced arteriolar light reflex (OR 3.83, CI 0.89-16.48), compared with those within the lowest quartile. In ischemic stroke patients, aortic stiffening is associated with retinal arteriolar luminal narrowing as well as features of retinal arteriolosclerosis.

Retinal thickness on Stratus optical coherence tomography in people with diabetes and minimal or no diabetic retinopathy.

PubMed

Bressler, Neil M; Edwards, Allison R; Antoszyk, Andrew N; Beck, Roy W; Browning, David J; Ciardella, Antonio P; Danis, Ronald P; Elman, Michael J; Friedman, Scott M; Glassman, Adam R; Gross, Jeffrey G; Li, Helen K; Murtha, Timothy J; Stone, Thomas W; Sun, Jennifer K

2008-05-01

To evaluate optical coherence tomography (OCT) thickness of the macula in people with diabetes but minimal or no retinopathy and to compare these findings with published normative data in the literature from subjects reported to have no retinal disease. Cross-sectional study. In a multicenter community- and university-based practices setting, 97 subjects with diabetes with no or minimal diabetic retinopathy and no central retinal thickening on clinical examination and a center point thickness of 225 microm or less on OCT (Stratus OCT; Carl Zeiss Meditec, Dublin, California, USA) were recruited. Electronic Early Treatment of Diabetic Retinopathy Study best-corrected visual acuity, seven-field stereoscopic color fundus photographs, and Stratus OCT fast macular scan were noted. Main outcome measures were central subfield (CSF) thickness measured on Stratus OCT. On average, CSF thickness was 201 +/- 22 microm. CSF thickness was significantly greater in retinas from men than retinas from women (mean +/- standard deviation, 209 +/- 18 microm vs 194 +/- 23 microm; P < .001). After adjusting for gender, no additional factors were found to be associated significantly with CSF thickness (P > .10). CSF thicknesses on Stratus OCT in people with diabetes and minimal or no retinopathy are similar to thicknesses reported from a normative database of people without diabetes. CSF thickness is greater in men than in women, consistent with many, but not all, previous reports. Studies involving comparisons of retinal thickness with expected norms should consider different mean values for women and men.

New algorithm for detecting smaller retinal blood vessels in fundus images

NASA Astrophysics Data System (ADS)

LeAnder, Robert; Bidari, Praveen I.; Mohammed, Tauseef A.; Das, Moumita; Umbaugh, Scott E.

2010-03-01

About 4.1 million Americans suffer from diabetic retinopathy. To help automatically diagnose various stages of the disease, a new blood-vessel-segmentation algorithm based on spatial high-pass filtering was developed to automatically segment blood vessels, including the smaller ones, with low noise. Methods: Image database: Forty, 584 x 565-pixel images were collected from the DRIVE image database. Preprocessing: Green-band extraction was used to obtain better contrast, which facilitated better visualization of retinal blood vessels. A spatial highpass filter of mask-size 11 was applied. A histogram stretch was performed to enhance contrast. A median filter was applied to mitigate noise. At this point, the gray-scale image was converted to a binary image using a binary thresholding operation. Then, a NOT operation was performed by gray-level value inversion between 0 and 255. Postprocessing: The resulting image was AND-ed with its corresponding ring mask to remove the outer-ring (lens-edge) artifact. At this point, the above algorithm steps had extracted most of the major and minor vessels, with some intersections and bifurcations missing. Vessel segments were reintegrated using the Hough transform. Results: After applying the Hough transform, both the average peak SNR and the RMS error improved by 10%. Pratt's Figure of Merit (PFM) was decreased by 6%. Those averages were better than [1] by 10-30%. Conclusions: The new algorithm successfully preserved the details of smaller blood vessels and should prove successful as a segmentation step for automatically identifying diseases that affect retinal blood vessels.

A new blood vessel extraction technique using edge enhancement and object classification.

PubMed

Badsha, Shahriar; Reza, Ahmed Wasif; Tan, Kim Geok; Dimyati, Kaharudin

2013-12-01

Diabetic retinopathy (DR) is increasing progressively pushing the demand of automatic extraction and classification of severity of diseases. Blood vessel extraction from the fundus image is a vital and challenging task. Therefore, this paper presents a new, computationally simple, and automatic method to extract the retinal blood vessel. The proposed method comprises several basic image processing techniques, namely edge enhancement by standard template, noise removal, thresholding, morphological operation, and object classification. The proposed method has been tested on a set of retinal images. The retinal images were collected from the DRIVE database and we have employed robust performance analysis to evaluate the accuracy. The results obtained from this study reveal that the proposed method offers an average accuracy of about 97 %, sensitivity of 99 %, specificity of 86 %, and predictive value of 98 %, which is superior to various well-known techniques.

The Unfolded Protein Response in Retinal Vascular Diseases: Implications and Therapeutic Potential Beyond Protein Folding

PubMed Central

Zhang, Sarah X.; Ma, Jacey H.; Bhatta, Maulasri; Fliesler, Steven J.; Wang, Joshua J.

2015-01-01

Angiogenesis is a complex, step-wise process of new vessel formation that is involved in both normal embryonic development as well as postnatal pathological processes, such as cancer, cardiovascular disease, and diabetes. Aberrant blood vessel growth, also known as neovascularization, in the retina and the choroid is a major cause of vision loss in severe eye diseases, such as diabetic retinopathy, age-related macular degeneration, retinopathy of prematurity, and central and branch retinal vein occlusion. Yet, retinal neovascularization is causally and dynamically associated with vasodegeneration, ischemia, and vascular remodeling in retinal tissues. Understanding the mechanisms of retinal neovascularization is an urgent unmet need for developing new treatments for these devastating diseases. Accumulating evidence suggests a vital role for the unfolded protein response (UPR) in regulation of angiogenesis, in part through coordinating the secretion of pro-angiogenic growth factors, such as VEGF, and modulating endothelial cell survival and activity. Herein, we summarize current research in the context of endoplasmic reticulum (ER) stress and UPR signaling in retinal angiogenesis and vascular remodeling, highlighting potential implications of targeting these stress response pathways in the prevention and treatment of retinal vascular diseases that result in visual deficits and blindness. PMID:25529848

Mapping by VESGEN of Blood Vessels in the Retinas of Astronauts Pre- and Post-Flight to the ISS

NASA Technical Reports Server (NTRS)

Parsons-Wingerter, P.; Vyas, R. J.; Murray, M. C.; Predovic, M.; Lim, S.; Vizzeri, G.; Taibbi, G.; Mason, S. S.; Zanello, S. B.; Young, M.

2017-01-01

Research by NASA [1] established that significant risks for visual and ocular impairments associated with increased intracranial pressure (VIIP) are incurred by microgravity spaceflight, especially long-duration missions. It is well established in physiology and pathology that a fundamental role of the microvasculature is to mediate fluid transfers and remodel actively in response to environmental, immune and other stresses. We therefore hypothesize that remodeling of retinal blood vessels necessarily occurs during accommodation of microgravity-induced fluid shifts prior to subsequent development of visual and ocular impairments. Potential contributions of retinal vascular remodeling to VIIP etiology are therefore being investigated by NASA's innovative VESsel GENeration Analysis (VESGEN) software for two studies: (1) U.S. crew members before and after ISS missions, and (2) head-down tilt in human subjects before and after 70 days of bed rest. We anticipate that results of the two studies will be complete by the Investigators Workshop (January 22, 2017). METHODS: For the 2013 NASA NRA award, we are concluding the analysis of 30 degree infrared (IR) Heidelberg Spectralis images of retinal blood vessels by VESGEN (patents pending), a mature, automated software developed as a translational and basic vascular research discovery tool, particularly for retinal vascular disease. Subjects of our retrospective study include eight ISS crew members monitored for routine occupational surveillance pre- and post-flight, who provided their study consents to NASAs Lifetime Surveillance of Astronaut Health (LSAH) in coordination with approval of the VESGEN retrospective study protocol by NASAs Institutional Review Board (IRB). The ophthalmic retinal images (average image resolution, approximately 5.6 microns per pixel) are blinded as to pre and post ISS status until the second portion of our study, when VESGEN results will be correlated with other ophthalmic and medical findings for the crew members. Due to image resolution challenges, a novel Matlab tool was developed for aligning pre and post images, and comparing (querying) the two images for differences in the morphology of small vessels. RESULTS: During the past year, LSAH approved the release of all astronaut retinal images to our study for VESGEN analysis. Substantial progress on the initial blinded portion of the study is in place. We anticipate that VESGEN analysis of the 32 Spectralis IR retinal images will be complete for presentation at the 2017 IWS meeting. CONCLUSIONS: Modified retinal vascular patterning may offer early-stage predictions of ocular changes resulting in decreased visual acuity for the VIIP syndrome. Novel insights provided by VESGEN into progressively pathological and blinding vascular remodeling in the human retina currently help to guide other NIH- and NASA-supported therapeutic studies of retinal disease and modeling of the VIIP risk. Results of our vascular investigation of the retinas of astronauts pre- and post-flight may help advance the understanding of both healthy and pathological adaptations to fluid shifts in microgravity associated with the VIIP syndrome. Preliminary results indicate that imaging of higher resolution, such as the new OCT angiography (OCT-A) technology, will be required to determine conclusively the role of the smaller retinal and choroidal vessels in VIIP etiology.

Site of potential operating microscope light-induced phototoxicity on the human retina during temporal approach eye surgery.

PubMed

Pavilack, M A; Brod, R D

2001-02-01

To determine the site of focal illumination on the retina of phakic human cadaver eyes from an operating microscope positioned for temporal approach eye surgery. Experimental study. A Zeiss OPMI-6SFR operating microscope (Zeiss Humphrey Systems, Dublin, CA) was positioned over two phakic human cadaver eyes to measure the site of the focal illumination on the retina by directly observing the illumination on the posterior scleral surface of the globe. External localization of the foveola was made by direct observation using scleral indentation and indirect ophthalmoscopy. Various combinations of microscope angulation and field of view were analyzed. Distance of focal illumination from the operating room microscope relative to the foveola was measured. The diameter of the "hot spot" of focal illumination on the retina was 4.0 mm. With the eye positioned straight ahead and the level operating room microscope positioned for temporal approach eye surgery, the center of retinal illumination was 0.9 and 1.4 mm nasal relative to the foveola when the microscope field of view was centered over the cornea and temporal limbus, respectively. With the microscope angled 5, 10, 15, and 20 degrees temporally (oculars tilted toward surgeon), the center of the illumination was displaced nasal to the foveola by 1.1, 1.5, 3.8, and 5.1 mm, respectively, when the field of view was centered over the cornea and 1.5, 2.6, 4.7, and 6.0 mm, respectively, nasal to the foveola when centered over the temporal limbus. Retinal illumination from an operating microscope positioned for temporal approach eye surgery has the potential for light-induced injury to the fovea. Angulation of the operating microscope by up to 10 degrees temporally when the microscope field of view was centered over the cornea and up to 5 degrees temporally when centered over the temporal limbus was not adequate to displace the focal illumination off the foveola when the eye was in the straight-ahead position. Tilting the operating microscope 15 degrees or more temporally when centered on the pupil and 10 degrees or more when centered over the temporal limbus should safely displace the retinal light exposure away from the fovea during temporal approach surgery. Suggestions for reducing the risk of iatrogenic phototoxicity are reviewed.

Reproducibility of retinal vessel oxygen saturation measurements in healthy young subjects.

PubMed

Lasta, Michael; Palkovits, Stefan; Boltz, Agnes; Schmidl, Doreen; Kaya, Semira; Cherecheanu, Alina Popa; Garhöfer, Gerhard; Schmetterer, Leopold

2012-12-01

An adequate oxygenation and perfusion is essential for the function of the inner retina. Recently, several techniques for the measurement of retinal oxygen saturation became available. We set out to evaluate reproducibility of the measurements using a modified Retinal Vessel Analyzer. A total of 20 healthy female and male subjects aged between 18 and 35 years (22.9 ± 3.9; mean ± SD) were included. The measurement of retinal oxygen saturation with the retinal oximeter employed in this study is based on optical reflectometry using the different absorption characteristics of oxygenated and deoxygenated haemoglobin. The intraclass correlation coefficients and the coefficients of variation (CV) for test-retest, short-term as well as day-to-day measurements were calculated.   The intraclass correlation coefficients were between 0.91 and 0.94 for retinal branch arteries and between 0.84 and 0.88 for retinal branch veins. In retinal arteries, we calculated a test-retest CV of 3.24 ± 3.18% for oxygen saturation measurements. In retinal veins, data were slightly less reproducible with a CV of 4.92 ± 3.57%. Short-term reproducibility of both measurement cycles on each study day was in the same range (CV in retinal arteries: 2.91 ± 2.42% and CV in retinal veins: 4.76 ± 3.14%). The day-to-day coefficient of variation was slightly higher (CV in retinal arteries: 3.97 ± 2.87% and CV in retinal veins: 6.18 ± 3.36%). The reproducibility of haemoglobin oxygen saturation measurements using the retinal oximeter is acceptable. Further studies on the validity of the obtained results are, however, required. © 2012 The Authors. Acta Ophthalmologica © 2012 Acta Ophthalmologica Scandinavica Foundation.

An unusual cause of central retinal artery occlusion: acquired immunodeficiency syndrome.

PubMed

Erdol, H; Turk, A; Caylan, R

2007-01-01

In patients with acquired immunodeficiency syndrome (AIDS), disturbances in the circulation of retinal vessels are mostly encountered at the microvascular level. Rarely observed large retinal vessel occlusions frequently affect retinal veins. A 32-year-old woman was admitted to the authors' clinic with sudden loss of vision. Her clinical and ophthalmologic examinations and laboratory tests were carried out and the results were evaluated. The patient's history revealed a diagnosis of AIDS established 5 years ago. Her corrected visual acuity was limited to light perception in the right eye and 20/60 in the left eye. There was afferent pupillary defect in the right eye. Posterior segment examination demonstrated central retinal artery occlusion in the right eye and cotton-wool spots in the left eye. The clinical examination and laboratory test results did not reveal any comorbid disease state that can contribute to this presentation. As thrombi may develop in patients with human immunodeficiency virus infection, they should be closely followed up for the development of vasoocclusive disease.

Accelerated and Improved Differentiation of Retinal Organoids from Pluripotent Stem Cells in Rotating-Wall Vessel Bioreactors.

PubMed

DiStefano, Tyler; Chen, Holly Yu; Panebianco, Christopher; Kaya, Koray Dogan; Brooks, Matthew J; Gieser, Linn; Morgan, Nicole Y; Pohida, Tom; Swaroop, Anand

2018-01-09

Pluripotent stem cells can be differentiated into 3D retinal organoids, with major cell types self-patterning into a polarized, laminated architecture. In static cultures, organoid development may be hindered by limitations in diffusion of oxygen and nutrients. Herein, we report a bioprocess using rotating-wall vessel (RWV) bioreactors to culture retinal organoids derived from mouse pluripotent stem cells. Organoids in RWV demonstrate enhanced proliferation, with well-defined morphology and improved differentiation of neurons including ganglion cells and S-cone photoreceptors. Furthermore, RWV organoids at day 25 (D25) reveal similar maturation and transcriptome profile as those at D32 in static culture, closely recapitulating spatiotemporal development of postnatal day 6 mouse retina in vivo. Interestingly, however, retinal organoids do not differentiate further under any in vitro condition tested here, suggesting additional requirements for functional maturation. Our studies demonstrate that bioreactors can accelerate and improve organoid growth and differentiation for modeling retinal disease and evaluation of therapies. Published by Elsevier Inc.

GRAFT-VERSUS-HOST DISEASE PANUVEITIS AND BILATERAL SEROUS DETACHMENTS: MULTIMODAL IMAGING ANALYSIS.

PubMed

Jung, Jesse J; Chen, Michael H; Rofagha, Soraya; Lee, Scott S

2017-01-01

To report the multimodal imaging findings and follow-up of a case of graft-versus-host disease-induced bilateral panuveitis and serous retinal detachments after allogenic bone marrow transplant for acute myeloid leukemia. A 75-year-old black man presented with acute decreased vision in both eyes for 1 week. Clinical examination and multimodal imaging, including spectral domain optical coherence tomography, fundus autofluorescence, fluorescein angiography, and swept-source optical coherence tomography angiography (Investigational Device; Carl Zeiss Meditec Inc) were performed. Clinical examination of the patient revealed anterior and posterior inflammation and bilateral serous retinal detachments. Ultra-widefield fundus autofluorescence demonstrated hyperautofluorescence secondary to subretinal fluid; and fluorescein angiography revealed multiple areas of punctate hyperfluorescence, leakage, and staining of the optic discs. Spectral domain and enhanced depth imaging optical coherence tomography demonstrated subretinal fluid, a thickened, undulating retinal pigment epithelium layer, and a thickened choroid in both eyes. En-face swept-source optical coherence tomography angiography did not show any retinal vascular abnormalities but did demonstrate patchy areas of decreased choriocapillaris flow. An extensive systemic infectious and malignancy workup was negative and the patient was treated with high-dose oral prednisone immunosuppression. Subsequent 6-month follow-up demonstrated complete resolution of the inflammation and bilateral serous detachments after completion of the prednisone taper over a 3-month period. Graft-versus-host disease panuveitis and bilateral serous retinal detachments are rare complications of allogenic bone marrow transplant for acute myeloid leukemia and can be diagnosed with clinical and multimodal imaging analysis. This form of autoimmune inflammation may occur after the recovery of T-cell activity within the donor graft targeting the host. Infectious and recurrent malignancy must be ruled out before initiation of immunosuppression, which can affectively treat this form of graft-versus-host disease.

Effects of Retinal Morphology on Contrast Sensitivity and Reading Ability in Neovascular Age-Related Macular Degeneration

PubMed Central

Keane, Pearse A.; Patel, Praveen J.; Ouyang, Yanling; Chen, Fred K.; Ikeji, Felicia; Walsh, Alexander C.; Tufail, Adnan

2010-01-01

Purpose. To investigate the effect of changes in retinal morphology on contrast sensitivity and reading ability in patients with neovascular age-related macular degeneration (AMD) in the Avastin (bevacizumab; Genentech, South San Francisco, CA) for choroidal neovascularization (ABC) Trial. Methods. Contrast sensitivity obtained with Pelli-Robson charts, reading ability assessed with Minnesota Reading charts, and Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity (VA) obtained by protocol refraction, were recorded. Raw Stratus optical coherence tomography (OCT; Carl Zeiss Meditec, Inc., Dublin, CA) images were analyzed with the publicly available software OCTOR, which allows precise delineation of any retinal compartment of interest. Thickness and volume were calculated for neurosensory retina, subretinal fluid (SRF), subretinal tissue, and pigment epithelium detachment, and the resulting measurements were correlated with each visual function parameter. Results. One hundred twenty-two patients with newly diagnosed neovascular AMD and enrolled in the ABC Trial, were evaluated. Increased subretinal tissue volume correlated with decreased contrast sensitivity (Pearson's correlation coefficient, r = −0.4944, P = 0.001). A modest correlation was detected between SRF volume and contrast sensitivity (r = −0.2562, P = 0.004). Increased retinal thickness at the foveal center also correlated with decreased visual function (ETDRS VA: r = −0.4530, P < 0.001). Conclusions. The strongest correlation detected between the functional parameters assessed and any of the OCT-derived morphologic parameters was that between decreased contrast sensitivity and increased subretinal tissue. In the future, assessment of contrast sensitivity and reading ability, in combination with quantitative subanalysis of retinal compartments, may lead to the identification of parameters relevant to functional improvement and ultimate prognosis in patients with newly diagnosed neovascular AMD (www.controlled-trials.com number, ISRCTN83325075). PMID:20554607

Application of a wide-field phantom eye for optical coherence tomography and reflectance imaging.

PubMed

Corcoran, Anthony; Muyo, Gonzalo; van Hemert, Jano; Gorman, Alistair; Harvey, Andrew R

2015-12-15

Optical coherence tomography (OCT) and reflectance imaging are used in clinical practice to measure the thickness and transverse dimensions of retinal features. The recent trend towards increasing the field of view (FOV) of these devices has led to an increasing significance of the optical aberrations of both the human eye and the device. We report the design, manufacture and application of the first phantom eye that reproduces the off-axis optical characteristics of the human eye, and allows the performance assessment of wide-field ophthalmic devices. We base our design and manufacture on the wide-field schematic eye, [Navarro, R. J. Opt. Soc. Am. A , 1985, 2 .] as an accurate proxy to the human eye and enable assessment of ophthalmic imaging performance for a [Formula: see text] external FOV. We used multi-material 3D-printed retinal targets to assess imaging performance of the following ophthalmic instruments: the Optos 200Tx, Heidelberg Spectralis, Zeiss FF4 fundus camera and Optos OCT SLO and use the phantom to provide an insight into some of the challenges of wide-field OCT.

Application of a wide-field phantom eye for optical coherence tomography and reflectance imaging

NASA Astrophysics Data System (ADS)

Corcoran, Anthony; Muyo, Gonzalo; van Hemert, Jano; Gorman, Alistair; Harvey, Andrew R.

2015-12-01

Optical coherence tomography (OCT) and reflectance imaging are used in clinical practice to measure the thickness and transverse dimensions of retinal features. The recent trend towards increasing the field of view (FOV) of these devices has led to an increasing significance of the optical aberrations of both the human eye and the device. We report the design, manufacture and application of the first phantom eye that reproduces the off-axis optical characteristics of the human eye, and allows the performance assessment of wide-field ophthalmic devices. We base our design and manufacture on the wide-field schematic eye, [Navarro, R. J. Opt. Soc. Am. A, 1985, 2.] as an accurate proxy to the human eye and enable assessment of ophthalmic imaging performance for a ? external FOV. We used multi-material 3D-printed retinal targets to assess imaging performance of the following ophthalmic instruments: the Optos 200Tx, Heidelberg Spectralis, Zeiss FF4 fundus camera and Optos OCT SLO and use the phantom to provide an insight into some of the challenges of wide-field OCT.

Automatic arteriovenous crossing phenomenon detection on retinal fundus images

NASA Astrophysics Data System (ADS)

Hatanaka, Yuji; Muramatsu, Chisako; Hara, Takeshi; Fujita, Hiroshi

2011-03-01

Arteriolosclerosis is one cause of acquired blindness. Retinal fundus image examination is useful for early detection of arteriolosclerosis. In order to diagnose the presence of arteriolosclerosis, the physicians find the silver-wire arteries, the copper-wire arteries and arteriovenous crossing phenomenon on retinal fundus images. The focus of this study was to develop the automated detection method of the arteriovenous crossing phenomenon on the retinal images. The blood vessel regions were detected by using a double ring filter, and the crossing sections of artery and vein were detected by using a ring filter. The center of that ring was an interest point, and that point was determined as a crossing section when there were over four blood vessel segments on that ring. And two blood vessels gone through on the ring were classified into artery and vein by using the pixel values on red and blue component image. Finally, V2-to-V1 ratio was measured for recognition of abnormalities. V1 was the venous diameter far from the blood vessel crossing section, and V2 was the venous diameter near from the blood vessel crossing section. The crossing section with V2-to-V1 ratio over 0.8 was experimentally determined as abnormality. Twenty four images, including 27 abnormalities and 54 normal crossing sections, were used for preliminary evaluation of the proposed method. The proposed method was detected 73% of crossing sections when the 2.8 sections per image were mis-detected. And, 59% of abnormalities were detected by measurement of V1-to-V2 ratio when the 1.7 sections per image were mis-detected.

Reversibility of Retinal Microvascular Changes in Severe Falciparum Malaria

PubMed Central

Maude, Richard J.; Kingston, Hugh W. F.; Joshi, Sonia; Mohanty, Sanjib; Mishra, Saroj K.; White, Nicholas J.; Dondorp, Arjen M.

2014-01-01

Malarial retinopathy allows detailed study of central nervous system vascular pathology in living patients with severe malaria. An adult with cerebral malaria is described who had prominent retinal whitening with corresponding retinal microvascular obstruction, vessel dilatation, increased vascular tortuosity, and blood retinal barrier leakage with decreased visual acuity, all of which resolved on recovery. Additional study of these features and their potential role in elucidating the pathogenesis of cerebral malaria is warranted. PMID:24935949

Parental history of hypertension is associated with narrower retinal arteriolar caliber in young girls.

PubMed

Gopinath, Bamini; Baur, Louise A; Hardy, Louise L; Wang, Jie Jin; Teber, Erdahl; Wong, Tien Y; Mitchell, Paul

2011-09-01

We aimed to assess the associations between parental history of hypertension and indicators of cardiovascular risk (retinal vessel diameter, presence of obesity, and elevated blood pressure) in prepubertal children. There were 1739 (77.7% of those eligible) 6-year-old students (863 girls and 876 boys) who were examined from a random cluster sample of 34 Sydney schools. Parents completed questionnaires about their medical conditions, including whether they have/had hypertension. Retinal images were taken with a digital fundus camera, and retinal vessel caliber was quantified using computer software. Anthropometric (height, weight, percentage of body fat, and body mass index) and blood pressure measures were collected. There were 160 children (9.2%) with a positive parental history of hypertension (either biological mother and/or father). Children with a positive versus negative parental history of hypertension had significantly higher body mass index (16.8 versus 16.5 kg/m(2); P=0.04) and systolic blood pressure (101.3 versus 99.8 mm Hg; P=0.01). Girls with positive versus negative parental history of hypertension had significantly higher diastolic blood pressure (≈3.1 mm Hg; P=0.01) and narrower retinal arteriolar caliber (≈4.3 μm; P=0.0004). Positive parental history of hypertension was not associated with mean retinal vascular caliber among boys. We show that a positive parental history of hypertension in healthy prepubertal girls, but not boys, is associated with narrower retinal arteriolar vessels, likely conveying a predisposition to develop hypertension later in life. These findings may indicate the need for cardiovascular disease prevention measures starting early in life among offspring of hypertensive parents.

Role of the Norrie disease pseudoglioma gene in sprouting angiogenesis during development of the retinal vasculature.

PubMed

Luhmann, Ulrich F O; Lin, Jihong; Acar, Niyazi; Lammel, Stefanie; Feil, Silke; Grimm, Christian; Seeliger, Mathias W; Hammes, Hans-Peter; Berger, Wolfgang

2005-09-01

To characterize developmental defects and the time course of Norrie disease in retinal and hyaloid vasculature during retinal development and to identify underlying molecular angiogenic pathways that may be affected in Norrie disease, exudative vitreoretinopathy, retinopathy of prematurity, and Coats' disease. Norrie disease pseudoglioma homologue (Ndph)-knockout mice were studied during retinal development at early postnatal (p) stages (p5, p10, p15, and p21). Histologic techniques, quantitative RT-PCR, ELISA, and Western blot analyses provided molecular data, and scanning laser ophthalmoscopy (SLO) angiography and electroretinography (ERG) were used to obtain in vivo data. The data showed that regression of the hyaloid vasculature of Ndph-knockout mice occurred but was drastically delayed. The development of the superficial retinal vasculature was strongly delayed, whereas the deep retinal vasculature did not form because of the blockage of vessel outgrowth into the deep retinal layers. Subsequently, microaneurysm-like lesions formed. Several angiogenic factors were differentially transcribed during retinal development. Increased levels of hypoxia inducible factor-1alpha (HIF1alpha) and VEGFA, as well as a characteristic ERG pattern, confirmed hypoxic conditions in the inner retina of the Ndph-knockout mouse. These data provide evidence for a crucial role of Norrin in hyaloid vessel regression and in sprouting angiogenesis during retinal vascular development, especially in the development of the deep retinal capillary networks. They also suggest an early and a late phase of Norrie disease and may provide an explanation for similar phenotypic features of allelic retinal diseases in mice and patients as secondary consequences of pathologic hypoxia.

Body fat distribution, metabolic and inflammatory markers and retinal microvasculature in school-age children. The Generation R Study.

PubMed

Gishti, O; Jaddoe, V W V; Hofman, A; Wong, T Y; Ikram, M K; Gaillard, R

2015-10-01

To examine the associations of body fatness, metabolic and inflammatory markers with retinal vessel calibers among children. We performed a population-based cohort study among 4145 school-age children. At the median age of 6.0 years (95% range 5.8, 8.0 years), we measured body mass index, total and abdominal fat mass, metabolic and inflammatory markers (blood levels of lipids, insulin and C-peptide and C-reactive protein) and retinal vascular calibers from retinal photographs. We observed that compared with normal weight children, obese children had narrower retinal arteriolar caliber (difference -0.21 s.d. score (SDS; 95% confidence interval (CI) -0.35, -0.06)), but not venular caliber. Continuous analyses showed that higher body mass index and total body fat mass, but not android/gynoid fat mass ratio and pre-peritoneal fat mass, were associated with narrower retinal arteriolar caliber (P<0.05 for body mass index and total body fat mass), but not with retinal venular caliber. Lipid and insulin levels were not associated with retinal vessel calibers. Higher C-reactive protein was associated with only wider retinal venular caliber (difference 0.10 SDS (95% CI 0.06, 0.14) per SDS increase in C-reactive protein). This latter association was not influenced by body mass index. Higher body fatness is associated with narrower retinal arteriolar caliber, whereas increased C-reactive protein levels are associated with wider retinal venular caliber. Increased fat mass and inflammation correlate with microvascular development from school-age onwards.

Retinal vessel segmentation on SLO image

PubMed Central

Xu, Juan; Ishikawa, Hiroshi; Wollstein, Gadi; Schuman, Joel S.

2010-01-01

A scanning laser ophthalmoscopy (SLO) image, taken from optical coherence tomography (OCT), usually has lower global/local contrast and more noise compared to the traditional retinal photograph, which makes the vessel segmentation challenging work. A hybrid algorithm is proposed to efficiently solve these problems by fusing several designed methods, taking the advantages of each method and reducing the error measurements. The algorithm has several steps consisting of image preprocessing, thresholding probe and weighted fusing. Four different methods are first designed to transform the SLO image into feature response images by taking different combinations of matched filter, contrast enhancement and mathematical morphology operators. A thresholding probe algorithm is then applied on those response images to obtain four vessel maps. Weighted majority opinion is used to fuse these vessel maps and generate a final vessel map. The experimental results showed that the proposed hybrid algorithm could successfully segment the blood vessels on SLO images, by detecting the major and small vessels and suppressing the noises. The algorithm showed substantial potential in various clinical applications. The use of this method can be also extended to medical image registration based on blood vessel location. PMID:19163149

Clinical applications of three-dimensional tortuosity metrics

NASA Astrophysics Data System (ADS)

Dougherty, Geoff; Johnson, Michael J.

2007-03-01

The measurement of abnormal vascular tortuosity is important in the diagnosis of many diseases. Metrics based on three-dimensional (3-D) curvature, using approximate polynomial spline-fitting to "data balls" centered along the mid-line of the vessel, minimize digitization errors and give tortuosity values largely independent of the resolution of the imaging system. In order to establish their clinical validity we applied them to a number of clinical vascular systems, using both 2-D (standard angiograms and retinal images) and 3-D datasets (from computed tomography angiography (CTA) and magnetic resonance angiography (MRA)). Using the abdominal aortograms we found that the metrics correlated well with the ranking of an expert panel of three vascular surgeons. Both the mean curvature and the root-mean square curvature provided good discrimination between vessels of different tortuosity: and using a data ball size of one-quarter of the local vessel radius in the spline fitting gave consistent results. Tortuous retinal vessels resulting from retinitis or diabetes, but not from vasculitis, could be distinguished from normal vessels. Tortuosity values based on 3-D data sets gave higher values than their 2-D projections, and could easily be implemented in automatic measurement. They produced values sufficiently discriminating to assess the relative utility of arteries for endoluminal repair of aneurysms.

THE RELATIONSHIP BETWEEN FOVEAL AVASCULAR ZONE AREA, VESSEL DENSITY, AND CYSTOID CHANGES IN DIABETIC RETINOPATHY, AN OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY STUDY.

PubMed

Tarassoly, Kia; Miraftabi, Arezoo; Soltan Sanjari, Mostafa; Parvaresh, Mohammad Mehdi

2017-06-29

To measure the foveal avascular zone (FAZ) areas and vessel densities of patients with diabetic retinopathy and to study their relationship with diabetic cystoid changes and retinal thickness. Prospective case series of 51 eyes of 31 patients with diabetic retinopathy. The eyes were grouped based on the presence or absence of cystoid edema and evaluated using optical coherence tomography angiography. The FAZ areas and vessel density were compared. The FAZ area at the superficial capillary plexus level was equal between the eyes with and without cystoid edema. Vessel density did not differ as well. There was no correlation with retinal thickness. In eyes with cystoid changes, FAZ area changes at the deep capillary plexus level were difficult to interpret. The FAZ area and vessel density at the superficial capillary plexus level are reproducible and independent of the presence of cystoid edema.

The relationship of systemic markers of renal function and vascular function with retinal blood vessel responses.

PubMed

Heitmar, R; Varma, C; De, P; Lau, Y C; Blann, A D

2016-11-01

To test the hypothesis of a significant relationship between systemic markers of renal and vascular function (processes linked to cardiovascular disease and its development) and retinal microvascular function in diabetes and/or cardiovascular disease. Ocular microcirculatory function was measured in 116 patients with diabetes and/or cardiovascular disease using static and continuous retinal vessel responses to three cycles of flickering light. Endothelial function was evaluated by von Willebrand factor (vWf), endothelial microparticles and soluble E selectin, renal function by serum creatinine, creatinine clearance and estimated glomerular filtration rate (eGFR). HbA1c was used as a control index. Central retinal vein equivalence and venous maximum dilation to flicker were linked to HbA1c (both p < 0.05). Arterial reaction time was linked to serum creatinine (p = 0.036) and eGFR (p = 0.039); venous reaction time was linked to creatinine clearance (p = 0.018). Creatinine clearance and eGFR were linked to arterial maximum dilatation (p < 0.001 and p = 0.003, respectively) and the dilatation amplitude (p = 0.038 and p = 0.048, respectively) responses in the third flicker cycle. Of venous responses to the first flicker cycle, HbA1c was linked to the maximum dilation response (p = 0.004) and dilatation amplitude (p = 0.017), vWf was linked to the maximum constriction response (p = 0.016), and creatinine clearance to the baseline diameter fluctuation (p = 0.029). In the second flicker cycle, dilatation amplitude was linked to serum creatinine (p = 0.022). Several retinal blood vessel responses to flickering light are linked to glycaemia and renal function, but only one index is linked to endothelial function. Renal function must be considered when interpreting retinal vessel responses.

Inter-eye Asymmetry of Optical Coherence Tomography Angiography Vessel Density in Bilateral Glaucoma, Glaucoma Suspect, and Healthy Eyes.

PubMed

Hou, Huiyuan; Moghimi, Sasan; Zangwill, Linda M; Shoji, Takuhei; Ghahari, Elham; Manalastas, Patricia Isabel C; Penteado, Rafaella C; Weinreb, Robert N

2018-03-23

To investigate inter-eye retinal vessel density asymmetry in healthy, glaucoma suspect, and mild to moderate glaucoma subjects, and its potential utility for early detection of glaucomatous damage. Cross-sectional study. 153 subjects including 55 healthy, 32 glaucoma suspect, and 66 glaucoma subjects enrolled in the Diagnostic Innovations in Glaucoma Study(DIGS). Vessel density was obtained from optical coherence tomography angiography (OCT-A) macular and optic nerve head scans. Thickness of peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell complex (mGCC) was measured with spectral-domain optical coherence tomography (SD-OCT) scans. Inter-eye asymmetry was calculated by taking the absolute value of difference in vessel density and thickness between the right and left eyes. Inter-eye retinal vessel density asymmetry parameters were significantly different among the three groups. Glaucoma suspects had significantly higher peripapillary and macular inter-eye vessel density asymmetries compared to healthy groups in univariate (1.1% vs. 2.0%, P=0.014 and 1.2% vs. 2.5%, P=0.027, respectively) and multivariate analyses (P=0.007 and 0.038, respectively). No significant differences in asymmetry of thickness parameters were found between glaucoma suspect and healthy groups (all P> 0.718). However significant differences in asymmetry of thickness parameters between glaucoma suspects and glaucoma patients (P<0.01) were found for all parameters. Inter-eye vessel density asymmetry can be quantified by OCT-A measurement. Glaucoma suspects have significantly greater vessel density asymmetry than healthy eyes. Longitudinal studies are needed to better characterize the relationship of vessel density asymmetry with the development and progression of glaucoma. Copyright © 2018 Elsevier Inc. All rights reserved.

Color Doppler imaging of the retrobulbar vessels in diabetic retinopathy.

PubMed

Pauk-Domańska, Magdalena; Walasik-Szemplińska, Dorota

2014-03-01

Diabetes is a metabolic disease characterized by elevated blood glucose level due to impaired insulin secretion and activity. Chronic hyperglycemia leads to functional disorders of numerous organs and to their damage. Vascular lesions belong to the most common late complications of diabetes. Microangiopathic lesions can be found in the eyeball, kidneys and nervous system. Macroangiopathy is associated with coronary and peripheral vessels. Diabetic retinopathy is the most common microangiopathic complication characterized by closure of slight retinal blood vessels and their permeability. Despite intensive research, the pathomechanism that leads to the development and progression of diabetic retinopathy is not fully understood. The examinations used in assessing diabetic retinopathy usually involve imaging of the vessels in the eyeball and the retina. Therefore, the examinations include: fluorescein angiography, optical coherence tomography of the retina, B-mode ultrasound imaging, perimetry and digital retinal photography. There are many papers that discuss the correlations between retrobulbar circulation alterations and progression of diabetic retinopathy based on Doppler sonography. Color Doppler imaging is a non-invasive method enabling measurements of blood flow velocities in small vessels of the eyeball. The most frequently assessed vessels include: the ophthalmic artery, which is the first branch of the internal carotid artery, as well as the central retinal vein and artery, and the posterior ciliary arteries. The analysis of hemodynamic alterations in the retrobulbar vessels may deliver important information concerning circulation in diabetes and help to answer the question whether there is a relation between the progression of diabetic retinopathy and the changes observed in blood flow in the vessels of the eyeball. This paper presents the overview of literature regarding studies on blood flow in the vessels of the eyeball in patients with diabetic retinopathy.

Innervation pattern of the preocular human central retinal artery.

PubMed

Bergua, Antonio; Kapsreiter, Markus; Neuhuber, Winfried L; Reitsamer, Herbert A; Schrödl, Falk

2013-05-01

The central retinal artery (CRA) is the main vessel for inner retinal oxygen and nutrition supply. While the intraocular branches lack autonomic innervation, the innervation pattern of the extra-ocular part of this vessel along its course within the optic nerve is poorly investigated. This part however is essential for maintenance of retinal blood supply, in physiological and pathological conditions. Therefore, the aim of this study was the characterization of the autonomic innervation of the preocular CRA in humans with morphological methods. Meeting the Declaration of Helsinki, eyes of body or cornea donors were processed for single or double immunohistochemistry against tyrosine hydroxilase (TH), dopamine-β-hydroxylase (DBH), choline acetyl-transferase (ChAT), vesicular acetylcholine transporter (VAChT), neuronal nitric oxide synthase (nNOS), calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal polypeptide (VIP), and cytochemistry for NADPH-diaphorase (NADPH-d). For documentation, light-, fluorescence-, and confocal laser-scanning microscopy were used. TH and DBH immunoreactive nerve fibres were detected in the CRA vessel wall, although a distinct perivascular plexus was missing. Further, nerve fibres immunoreactive for ChAT and VAChT were found, while CGRP, SP, and VIP were not detected. NADPH-d staining revealed scattered nerve fibres in the adventitia of the CRA and in close vicinity; however, nNOS-immunostaining could not confirm this finding. The CRA receives adrenergic and cholinergic innervations, indicating sympathetic and parasympathetic components, respectively. Remarkably, a peptidergic primary afferent innervation was missing. Since clinical results suggest an autoregulation of intraretinal vessels, further studies are needed to clarify the impact of CRA innervation for retinal perfusion. Copyright © 2012 Elsevier Ltd. All rights reserved.

[The Development of First Operating Microscopes from Zeiss Jena and Oberkochen to Series Production].

PubMed

Gudziol, H; Gottschall, R; Luther, E

2017-01-01

Introduction: The history of the first operating microscopes from Zeiss is often confusing, not painstaking and partly contradictory because of the parallel development of Zeiss Jena (East Germany) and Zeiss Oberkochen (West Germany). Methods: To investigate the early beginnings of the construction of the operating microscopes documents of the Carl Zeiss Archive and the Optical Museum in Jena, the memoirs of Prof. Dr. Rosemarie Albrecht and some relevant publications were used. Results: The development of the first Jena operating microscope was initiated in 1949 by the ENT-physician Prof. Dr. Rosemarie Albrecht in the Soviet occupation zone. The first prototype was tested in the University ENT Clinic, Jena since summer of 1950. On the Leipzig Trade Fair in autumn 1952 the VEB Optik Carl Zeiss Jena presented the first operating microscope nationally and internationally. Series production began in 1953. The first operating microscope of Zeiss Oberkochen was primarily developed by technical designers (H. Littmann) as a colposcope. But in the Carl Zeiss Archive no documents could be found related to the cooperation with gynecologists. 1953 the operating microscope (OPMI 1) came into public and its series production started. From this date on, it was adopted by the otologist Prof. Dr. Horst Ludwig Wullstein to the needs of Otorhinolaryngology. Conclusion: The first Zeiss operating microscope came from Jena. The operating microscope from Zeiss Oberkochen had some advantages for the surgeons and won the competition in the future. © Georg Thieme Verlag KG Stuttgart · New York.

Effects of hyperbaric, normobaric and hypobaric oxygen supplementation on retinal vessels in newborn rats: a preliminary study.

PubMed

Ricci, B

1987-03-01

An experimental study was conducted on eight litters of newborn rats to evaluate the effects of supplemental oxygen administration on the retinal vasculature. The animals and their mothers were kept inside a pressure chamber and treated for the first 5 days of life. On the sixth day, they were removed and kept for five more days under room air and normobaric conditions. Three litters received continuous flow oxygen at 80% at a compression pressure of +81 kPa, one litter oxygen at 80% at a pressure of -39.5 kPa atms and three other litters received oxygen at 80% under normobaric conditions. The eighth litter was treated with room air oxygen at a compression pressure of +81 kPa. A severe retinopathy with marked retinal neovascularization was seen only in the newborn animals of the litters that received oxygen supplementation under normobaric or hypobaric conditions. Retinal vessels showed no pathological changes in the litters treated with hyperbaric normoxia or hyperoxia. It is possible to hypothesize that the prolonged period of oxygen supplementation failed to produce harmful effects on the retinal vasculature because the moderate hyperbarism caused mild retinal and choroidal vasoconstriction thus preventing excessive oxygen transport to the inner retina from the choroid during hyperoxia without inducing structural damage to the retinal tissue.

Feature-based pairwise retinal image registration by radial distortion correction

NASA Astrophysics Data System (ADS)

Lee, Sangyeol; Abràmoff, Michael D.; Reinhardt, Joseph M.

2007-03-01

Fundus camera imaging is widely used to document disorders such as diabetic retinopathy and macular degeneration. Multiple retinal images can be combined together through a procedure known as mosaicing to form an image with a larger field of view. Mosaicing typically requires multiple pairwise registrations of partially overlapped images. We describe a new method for pairwise retinal image registration. The proposed method is unique in that the radial distortion due to image acquisition is corrected prior to the geometric transformation. Vessel lines are detected using the Hessian operator and are used as input features to the registration. Since the overlapping region is typically small in a retinal image pair, only a few correspondences are available, thus limiting the applicable model to an afine transform at best. To recover the distortion due to curved-surface of retina and lens optics, a combined approach of an afine model with a radial distortion correction is proposed. The parameters of the image acquisition and radial distortion models are estimated during an optimization step that uses Powell's method driven by the vessel line distance. Experimental results using 20 pairs of green channel images acquired from three subjects with a fundus camera confirmed that the afine model with distortion correction could register retinal image pairs to within 1.88+/-0.35 pixels accuracy (mean +/- standard deviation) assessed by vessel line error, which is 17% better than the afine-only approach. Because the proposed method needs only two correspondences, it can be applied to obtain good registration accuracy even in the case of small overlap between retinal image pairs.

Decursin inhibits VEGF-mediated inner blood-retinal barrier breakdown by suppression of VEGFR-2 activation.

PubMed

Kim, Jin Hyoung; Kim, Jeong Hun; Lee, You Mie; Ahn, Eun-Mi; Kim, Kyu-Won; Yu, Young Suk

2009-09-01

The blood-retinal barrier (BRB) is essential for the normal structural and functional integrity of the retina, whose breakdown could cause the serious vision loss. Vascular endothelial growth factor (VEGF), as a permeable factor, induces alteration of tight junction proteins to result in BRB breakdown. Herein, we demonstrated that decursin inhibits VEGF-mediated inner BRB breakdown through suppression of VEGFR-2 signaling pathway. In retinal endothelial cells, decursin inhibited VEGF-mediated hyperpermeability. Decursin prevented VEGF-mediated loss of tight junction proteins including zonula occludens-1 (ZO-1), ZO-2, and occludin in retinal endothelial cells, which was also supported by restoration of tight junction proteins in intercellular junction. In addition, decursin significantly inhibited VEGF-mediated vascular leakage from retinal vessels, which was accompanied by prevention of loss of tight junction proteins in retinal vessels. Decursin significantly suppressed VEGF-induced VEGFR-2 phosphrylation that consequently led to inhibition of extracellular signal-regulated kinase (ERK) 1/2 activation. Moreover, decursin induced no cytotoxicity to retinal endothelial cells and no retinal toxicity under therapeutic concentrations. Therefore, our results suggest that decursin prevents VEGF-mediated BRB breakdown through blocking of loss of tight junction proteins, which might be regulated by suppression of VEGFR-2 activation. As a novel inhibitor to BRB breakdown, decursin could be applied to variable retinopathies with BRB breakdown.

Relation of retinal blood flow and retinal oxygen extraction during stimulation with diffuse luminance flicker

PubMed Central

Palkovits, Stefan; Lasta, Michael; Told, Reinhard; Schmidl, Doreen; Werkmeister, René; Cherecheanu, Alina Popa; Garhöfer, Gerhard; Schmetterer, Leopold

2015-01-01

Cerebral and retinal blood flow are dependent on local neuronal activity. Several studies quantified the increase in cerebral blood flow and oxygen consumption during activity. In the present study we investigated the relation between changes in retinal blood flow and oxygen extraction during stimulation with diffuse luminance flicker and the influence of breathing gas mixtures with different fractions of O2 (FiO2; 100% 15% and 12%). Twenty-four healthy subjects were included. Retinal blood flow was studied by combining measurement of vessel diameters using the Dynamic Vessel Analyser with measurements of blood velocity using laser Doppler velocimetry. Oxygen saturation was measured using spectroscopic reflectometry and oxygen extraction was calculated. Flicker stimulation increased retinal blood flow (57.7 ± 17.8%) and oxygen extraction (34.6 ± 24.1%; p < 0.001 each). During 100% oxygen breathing the response of retinal blood flow and oxygen extraction was increased (p < 0.01 each). By contrast, breathing gas mixtures with 12% and 15% FiO2 did not alter flicker–induced retinal haemodynamic changes. The present study indicates that at a comparable increase in blood flow the increase in oxygen extraction in the retina is larger than in the brain. During systemic hyperoxia the blood flow and oxygen extraction responses to neural stimulation are augmented. The underlying mechanism is unknown. PMID:26672758

Comparisons Between Histology and Optical Coherence Tomography Angiography of the Periarterial Capillary-Free Zone.

PubMed

Balaratnasingam, Chandrakumar; An, Dong; Sakurada, Yoichi; Lee, Cecilia S; Lee, Aaron Y; McAllister, Ian L; Freund, K Bailey; Sarunic, Marinko; Yu, Dao-Yi

2018-05-01

To use the capillary-free zone along retinal arteries, a physiologic area of superficial avascularization, as an anatomic paradigm to investigate the reliability of optical coherence tomography angiography (OCTA) for visualizing the deep retinal circulation. Validity analysis and laboratory investigation. Five normal human donor eyes (mean age 69.8 years) were perfusion-labeled with endothelial antibodies and the capillary networks of the perifovea were visualized using confocal scanning laser microscopy. Regions of the capillary-free zone along the retinal artery were imaged using OCTA in 16 normal subjects (age range 24-51 years). Then, 3 × 3-mm scans were acquired using the RTVue XR Avanti (ver. 2016.1.0.26; Optovue, Inc, Fremont, California, USA), PLEX Elite 9000 (ver. 1.5.0.15909; Zeiss Meditec, Inc, Dublin, California, USA), Heidelberg Spectralis OCT2 (Family acquisition module 6.7.21.0; Heidelberg Engineering, Heidelberg, Germany), and DRI-OCT Triton (Ver. 1.1.1; Topcon Corp, Tokyo, Japan). Images of the superficial plexus, deep vascular plexus, and a slab containing all vascular plexuses were generated using manufacturer-recommended default settings. Comparisons between histology and OCTA were performed. Histologic analysis revealed that the capillary-free zone along the retinal artery was confined to the plane of the superficial capillary plexus and did not include the intermediate and deep capillary plexuses. Images derived from OCTA instruments demonstrated a prominent capillary-free zone along the retinal artery in slabs of the superficial plexus, deep plexus, and all capillary plexuses. The number of deep retinal capillaries seen in the capillary-free zone was significantly greater on histology than on OCTA (P < .001). Using the capillary-free zone as an anatomic paradigm, we show that the deep vascular beds of the retina are not completely visualized using OCTA. This may be a limitation of current OCTA techniques. Copyright © 2018 Elsevier Inc. All rights reserved.

Is the peripapillary retinal perfusion related to myopia in healthy eyes? A prospective comparative study.

PubMed

Wang, Xiaolei; Kong, Xiangmei; Jiang, Chunhui; Li, Mengwei; Yu, Jian; Sun, Xinghuai

2016-03-11

The aim of this study was to evaluate the peripapillary and parafoveal perfusion of young, healthy myopic subjects with spectral domain optical coherence tomography (OCT) angiography. A prospective comparative study was conducted from December 2014 to January 2015. Participants recruited from a population-based study performed by the Eye, Ear, Nose and Throat Hospital of Fudan University in Shanghai. A total of 78 Chinese normal subjects (78 eyes) with different refraction were included. Myopia was divided into 4 groups on the basis of the refractive status: 20 eyes with emmetropia (mean spherical equivalent (MSE) 0.50D to -0.50D), 20 eyes with mild myopia (MSE -0.75D to -2.75D), 20 eyes with moderate myopia (MSE -3.00D to -5.75D), and 18 eyes with high myopia (MSE≤-6.00D). Peripapillary and parafoveal retinal and choroidal perfusion parameters and their relationships with axial length (AL) and retinal nerve fibre layer (RNFL) thickness were analysed. Significant differences were found for the retinal flow index and vessel density in the peripapillary area among the 4 groups, but not in the parafoveal area. The high myopia group had the lowest peripapillary retinal flow index and vessel density. In addition, there was a negative correlation (β=-0.002, p=0.047) between the AL and peripapillary retinal flow index and a positive correlation between RNFL thickness and the peripapillary retinal perfusion parameters (flow index: β=0.001, p=0.006; vessel density: β=0.350, p=0.002) even after adjustment for other variables. Highly myopic eyes have a decreased peripapillary retinal perfusion compared with emmetropic eyes. Such vascular features might increase the susceptibility to vascular-related eye diseases. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

High quality optical microangiography of ocular microcirculation and measurement of total retinal blood flow in mouse eye

NASA Astrophysics Data System (ADS)

Zhi, Zhongwei; Yin, Xin; Dziennis, Suzan; Alpers, Charles E.; Wang, Ruikang K.

2013-03-01

Visualization and measurement of retinal blood flow (RBF) is important to the diagnosis and management of different eye diseases, including diabetic retinopathy. Optical microangiography (OMAG) is developed for generating 3D dynamic microcirculation image and later refined into ultra-high sensitive OMAG (UHS-OMAG) for true capillary vessels imaging. Here, we present the application of OMAG imaging technique for visualization of depth-resolved vascular network within retina and choroid as well as measurement of total retinal blood flow in mice. A fast speed spectral domain OCT imaging system at 820nm with a line scan rate of 140 kHz was developed to image mouse posterior eye. By applying UHS-OMAG scanning protocol and processing algorithm, we achieved true capillary level imaging of retina and choroid vasculature in mouse eye. The vascular pattern within different retinal layers and choroid was presented. An en face Doppler OCT approach [1] without knowing Doppler angle was adopted for the measurement of total retinal blood flow. The axial blood flow velocity is measured in an en face plane by raster scanning and the flow is calculated by integrating over the vessel area of the central retinal artery.

Statistical Modeling of Retinal Optical Coherence Tomography.

PubMed

Amini, Zahra; Rabbani, Hossein

2016-06-01

In this paper, a new model for retinal Optical Coherence Tomography (OCT) images is proposed. This statistical model is based on introducing a nonlinear Gaussianization transform to convert the probability distribution function (pdf) of each OCT intra-retinal layer to a Gaussian distribution. The retina is a layered structure and in OCT each of these layers has a specific pdf which is corrupted by speckle noise, therefore a mixture model for statistical modeling of OCT images is proposed. A Normal-Laplace distribution, which is a convolution of a Laplace pdf and Gaussian noise, is proposed as the distribution of each component of this model. The reason for choosing Laplace pdf is the monotonically decaying behavior of OCT intensities in each layer for healthy cases. After fitting a mixture model to the data, each component is gaussianized and all of them are combined by Averaged Maximum A Posterior (AMAP) method. To demonstrate the ability of this method, a new contrast enhancement method based on this statistical model is proposed and tested on thirteen healthy 3D OCTs taken by the Topcon 3D OCT and five 3D OCTs from Age-related Macular Degeneration (AMD) patients, taken by Zeiss Cirrus HD-OCT. Comparing the results with two contending techniques, the prominence of the proposed method is demonstrated both visually and numerically. Furthermore, to prove the efficacy of the proposed method for a more direct and specific purpose, an improvement in the segmentation of intra-retinal layers using the proposed contrast enhancement method as a preprocessing step, is demonstrated.

Quantifying effects of retinal illuminance on frequency doubling perimetry.

PubMed

Swanson, William H; Dul, Mitchell W; Fischer, Susan E

2005-01-01

To measure and quantify effects of variation in retinal illuminance on frequency doubling technology (FDT) perimetry. A Zeiss-Humphrey/Welch Allyn FDT perimeter was used with the threshold N-30 strategy. Study 1, quantifying adaptation: 11 eyes of 11 subjects (24-46 years old) were tested with natural pupils, and then retested after stable pupillary dilation with neutral density filters of 0.0, 0.6, 1.2, and 1.6 log unit in front of the subject's eye. Study 2, predicting effect of reduced illuminance: 17 eyes of 17 subjects (26-61 years old) were tested with natural pupils, and then retested after stable pupillary miosis (assessed with an infrared camera). A quantitative adaptation model was fit to results of Study 1; the mean adaptation parameter was used to predict change in Study 2. Study 1: Mean defect (MD) decreased by 10 dB over a 1.6 log unit range of retinal illuminances; model fits for all subjects had r2> 95%. Study 2: Change in MD (DeltaMD) ranged from -7.3 dB to +0.8 dB. The mean adaptation parameter from Study 1 accounted for 69% of the variance in DeltaMD (P <0.0005), and accuracy of the model was independent of the magnitude of DeltaMD (r2< 1%, P >0.75). The results confirmed previous findings that FDT perimetry can be dramatically affected by variations in retinal illuminance. Application of a quantitative adaptation model provided guidelines for estimating effects of pupil diameter and lens density on FDT perimetry.

Semi-automatic geographic atrophy segmentation for SD-OCT images.

PubMed

Chen, Qiang; de Sisternes, Luis; Leng, Theodore; Zheng, Luoluo; Kutzscher, Lauren; Rubin, Daniel L

2013-01-01

Geographic atrophy (GA) is a condition that is associated with retinal thinning and loss of the retinal pigment epithelium (RPE) layer. It appears in advanced stages of non-exudative age-related macular degeneration (AMD) and can lead to vision loss. We present a semi-automated GA segmentation algorithm for spectral-domain optical coherence tomography (SD-OCT) images. The method first identifies and segments a surface between the RPE and the choroid to generate retinal projection images in which the projection region is restricted to a sub-volume of the retina where the presence of GA can be identified. Subsequently, a geometric active contour model is employed to automatically detect and segment the extent of GA in the projection images. Two image data sets, consisting on 55 SD-OCT scans from twelve eyes in eight patients with GA and 56 SD-OCT scans from 56 eyes in 56 patients with GA, respectively, were utilized to qualitatively and quantitatively evaluate the proposed GA segmentation method. Experimental results suggest that the proposed algorithm can achieve high segmentation accuracy. The mean GA overlap ratios between our proposed method and outlines drawn in the SD-OCT scans, our method and outlines drawn in the fundus auto-fluorescence (FAF) images, and the commercial software (Carl Zeiss Meditec proprietary software, Cirrus version 6.0) and outlines drawn in FAF images were 72.60%, 65.88% and 59.83%, respectively.

[Peripheral refraction and retinal contour in congenital and acquired high myopia].

PubMed

Tarutta, E P; Markosyan, G A; Milash, S V

to perform a comparative study of peripheral refraction and retinal contour in patients with congenital versus acquired high myopia. A total of 30 patients (60 eyes) with high myopia aged 8 to 18 years (11.2±0.32 years on average) were examined. The patients were divided into 2 groups. Group 1 consisted of 21 patients (42 eyes) with acquired myopia of -6.0 to -10.25 diopters (-7.55±0.17 diopters on average), group 2 - of 9 patients (18 eyes) with congenital myopia of -8.75 to -28.75 diopters (-16.39±1.24 diopters on average). Using the Grand Seiko WR-5100K binocular open-field autoref/keratometer (Japan), relative peripheral refraction was assessed with account to relative peripheral eye length measured by the IOL Master partial coherent interferometer ('Carl Zeiss', Germany) at 15° and 30° nasally and temporally from the foveal center along the horizontal meridian. In acquired myopia, relative peripheral refraction and relative peripheral eye length readings evidenced the formation of peripheral hyperopic defocus in all examined zones. Congenital high myopia cases were notable for myopic defocus at 15° of the nasal retina (N15 zone): -0.67±0.33 diopters against the eye length change of -0.33±0.13 mm. The research helped identify retinal contour changes characteristic of congenital myopia and indicative of posterior pole irregularity.

An automatic graph-based approach for artery/vein classification in retinal images.

PubMed

Dashtbozorg, Behdad; Mendonça, Ana Maria; Campilho, Aurélio

2014-03-01

The classification of retinal vessels into artery/vein (A/V) is an important phase for automating the detection of vascular changes, and for the calculation of characteristic signs associated with several systemic diseases such as diabetes, hypertension, and other cardiovascular conditions. This paper presents an automatic approach for A/V classification based on the analysis of a graph extracted from the retinal vasculature. The proposed method classifies the entire vascular tree deciding on the type of each intersection point (graph nodes) and assigning one of two labels to each vessel segment (graph links). Final classification of a vessel segment as A/V is performed through the combination of the graph-based labeling results with a set of intensity features. The results of this proposed method are compared with manual labeling for three public databases. Accuracy values of 88.3%, 87.4%, and 89.8% are obtained for the images of the INSPIRE-AVR, DRIVE, and VICAVR databases, respectively. These results demonstrate that our method outperforms recent approaches for A/V classification.

Radio-opaque modification/substitute for the wright superior oblique tendon extender for superior oblique muscle overaction strabismus.

PubMed

Arnold, Robert W; Leman, Rachel E

2007-01-01

Kenneth Wright developed a technique for graded weakening of the superior oblique by increasing the effective length of this extraocular muscle's long tendon with a piece of silicone rubber retinal encircling band commonly used by eye surgery for retinal detachment repairs. In the absence of any specific retinal bands in our Children's Hospital, the following technique was developed affording a non-invasive ability to monitor, which was less intricate than the technique so well described by Demer. We substituted the "Mini Vessel Loop" (by Maaxxim Medical or Henley International). It is an elastic smooth silicone rubber cord that is radio-opaque, and can easily be seen on X-rays and CT scans. It is not an ophthalmologic medical device but it rather is designed to loop around and identify and gently retract blood vessels and nerves in any form of surgery where needed. We demonstrated success similar to that achieved by Wright in 43 patients using these radio-opaque, silicon Mini Vessel loops.

A Comprehensive Study of Retinal Vessel Classification Methods in Fundus Images

PubMed Central

Miri, Maliheh; Amini, Zahra; Rabbani, Hossein; Kafieh, Raheleh

2017-01-01

Nowadays, it is obvious that there is a relationship between changes in the retinal vessel structure and diseases such as diabetic, hypertension, stroke, and the other cardiovascular diseases in adults as well as retinopathy of prematurity in infants. Retinal fundus images provide non-invasive visualization of the retinal vessel structure. Applying image processing techniques in the study of digital color fundus photographs and analyzing their vasculature is a reliable approach for early diagnosis of the aforementioned diseases. Reduction in the arteriolar–venular ratio of retina is one of the primary signs of hypertension, diabetic, and cardiovascular diseases which can be calculated by analyzing the fundus images. To achieve a precise measuring of this parameter and meaningful diagnostic results, accurate classification of arteries and veins is necessary. Classification of vessels in fundus images faces with some challenges that make it difficult. In this paper, a comprehensive study of the proposed methods for classification of arteries and veins in fundus images is presented. Considering that these methods are evaluated on different datasets and use different evaluation criteria, it is not possible to conduct a fair comparison of their performance. Therefore, we evaluate the classification methods from modeling perspective. This analysis reveals that most of the proposed approaches have focused on statistics, and geometric models in spatial domain and transform domain models have received less attention. This could suggest the possibility of using transform models, especially data adaptive ones, for modeling of the fundus images in future classification approaches. PMID:28553578

Automated detection of kinks from blood vessels for optic cup segmentation in retinal images

NASA Astrophysics Data System (ADS)

Wong, D. W. K.; Liu, J.; Lim, J. H.; Li, H.; Wong, T. Y.

2009-02-01

The accurate localization of the optic cup in retinal images is important to assess the cup to disc ratio (CDR) for glaucoma screening and management. Glaucoma is physiologically assessed by the increased excavation of the optic cup within the optic nerve head, also known as the optic disc. The CDR is thus an important indicator of risk and severity of glaucoma. In this paper, we propose a method of determining the cup boundary using non-stereographic retinal images by the automatic detection of a morphological feature within the optic disc known as kinks. Kinks are defined as the bendings of small vessels as they traverse from the disc to the cup, providing physiological validation for the cup boundary. To detect kinks, localized patches are first generated from a preliminary cup boundary obtained via level set. Features obtained using edge detection and wavelet transform are combined using a statistical approach rule to identify likely vessel edges. The kinks are then obtained automatically by analyzing the detected vessel edges for angular changes, and these kinks are subsequently used to obtain the cup boundary. A set of retinal images from the Singapore Eye Research Institute was obtained to assess the performance of the method, with each image being clinically graded for the CDR. From experiments, when kinks were used, the error on the CDR was reduced to less than 0.1 CDR units relative to the clinical CDR, which is within the intra-observer variability of 0.2 CDR units.

Ocular Signs Related to Overweight and Arterial Hypertension in Children: A Systematic Review

PubMed Central

Schuh, Daniela S.; Piccoli, Ângela B.; Paiani, Raquel L.; Maciel, Cristiane R; Pellanda, Lucia C; Vilela, Manuel AP

2017-01-01

Background: The ocular effects of obesity and hypertension need to be established and can be used as prognostic markers. Objective: To estimate the prevalence of ophthalmological alterations in children and adolescents who are overweight and/or have SAH. Methods: The database for this study included all observational studies (CS, cohort, case-control and “baseline” description of randomized clinical trials) with children and/or adolescents who were overweight, obese or had SAH and that measured ophthalmological alterations. Results: Comparative studies with healthy children demonstrated positive association between body adiposity with retinal venular dilation, and SAH with retinal arteriolar narrowing. Different retinal fundus cameras and computer-assisted programs to evaluate the retinal vessels, variations in the methods of analysis, adjustments, populations, were the main arguments against formal meta-analysis. The heterogeneity was too high (I2 >90%, in fixed or randomized effects), and the lack of linearity, normal distribution and homoscedasticity did not recommend meta-regression. Conclusion: Obesity and SAH show associations with ophthalmological alterations, especially with retinal vessel diameter. Lack of standardization does not allow a quantitative evaluation. PMID:29081867

Monte Carlo investigation on quantifying the retinal pigment epithelium melanin concentration by photoacoustic ophthalmoscopy.

PubMed

Shu, Xiao; Liu, Wenzhong; Zhang, Hao F

2015-10-01

The retinal pigment epithelium (RPE) melanin plays an important role in maintaining normal visual functions. A decrease in the RPE melanin concentration with aging is believed to be associated with several blinding diseases, including age-related macular degeneration. Quantifying the RPE melanin noninvasively is therefore important in evaluating the retinal health and aging conditions. Photoacoustic ophthalmoscopy (PAOM), as an optical absorption-based imaging technology, can potentially be applied to measure variations in the RPE melanin if the relationship between the detected photoacoustic (PA) signal amplitudes and the RPE melanin concentrations can be established. In this work, we tested the feasibility of using PA signals from retinal blood vessels as references to measure RPE melanin variation using Monte Carlo (MC) simulation. The influences from PAOM axial resolution, the depth and diameter of the retinal blood vessel, and the RPE thickness were examined. We proposed a calibration scheme by relating detected PA signals to the RPE melanin concentrations, and we found that the scheme is robust to these tested parameters. This study suggests that PAOM has the capability of quantitatively measuring the RPE melanin in vivo.

Detailed Vascular Anatomy of the Human Retina by Projection-Resolved Optical Coherence Tomography Angiography

NASA Astrophysics Data System (ADS)

Campbell, J. P.; Zhang, M.; Hwang, T. S.; Bailey, S. T.; Wilson, D. J.; Jia, Y.; Huang, D.

2017-02-01

Optical coherence tomography angiography (OCTA) is a noninvasive method of 3D imaging of the retinal and choroidal circulations. However, vascular depth discrimination is limited by superficial vessels projecting flow signal artifact onto deeper layers. The projection-resolved (PR) OCTA algorithm improves depth resolution by removing projection artifact while retaining in-situ flow signal from real blood vessels in deeper layers. This novel technology allowed us to study the normal retinal vasculature in vivo with better depth resolution than previously possible. Our investigation in normal human volunteers revealed the presence of 2 to 4 distinct vascular plexuses in the retina, depending on location relative to the optic disc and fovea. The vascular pattern in these retinal plexuses and interconnecting layers are consistent with previous histologic studies. Based on these data, we propose an improved system of nomenclature and segmentation boundaries for detailed 3-dimensional retinal vascular anatomy by OCTA. This could serve as a basis for future investigation of both normal retinal anatomy, as well as vascular malformations, nonperfusion, and neovascularization.

Monte Carlo investigation on quantifying the retinal pigment epithelium melanin concentration by photoacoustic ophthalmoscopy

NASA Astrophysics Data System (ADS)

Shu, Xiao; Liu, Wenzhong; Zhang, Hao F.

2015-10-01

The retinal pigment epithelium (RPE) melanin plays an important role in maintaining normal visual functions. A decrease in the RPE melanin concentration with aging is believed to be associated with several blinding diseases, including age-related macular degeneration. Quantifying the RPE melanin noninvasively is therefore important in evaluating the retinal health and aging conditions. Photoacoustic ophthalmoscopy (PAOM), as an optical absorption-based imaging technology, can potentially be applied to measure variations in the RPE melanin if the relationship between the detected photoacoustic (PA) signal amplitudes and the RPE melanin concentrations can be established. In this work, we tested the feasibility of using PA signals from retinal blood vessels as references to measure RPE melanin variation using Monte Carlo (MC) simulation. The influences from PAOM axial resolution, the depth and diameter of the retinal blood vessel, and the RPE thickness were examined. We proposed a calibration scheme by relating detected PA signals to the RPE melanin concentrations, and we found that the scheme is robust to these tested parameters. This study suggests that PAOM has the capability of quantitatively measuring the RPE melanin in vivo.

Pathogenesis and neuroimaging of cerebral large and small vessel disease in type 2 diabetes: A possible link between cerebral and retinal microvascular abnormalities.

PubMed

Umemura, Toshitaka; Kawamura, Takahiko; Hotta, Nigishi

2017-03-01

Diabetes patients have more than double the risk of ischemic stroke compared with non-diabetic individuals, and its neuroimaging characteristics have important clinical implications. To understand the pathophysiology of ischemic stroke in diabetes, it is important to focus not only on the stroke subtype, but also on the size and location of the occlusive vessels. Specifically, ischemic stroke in diabetes patients might be attributed to both large and small vessels, and intracranial internal carotid artery disease and small infarcts of the posterior circulation often occur. An additional feature is that asymptomatic lacunar infarctions are often seen in the basal ganglia and brain stem on brain magnetic resonance imaging. In particular, cerebral small vessel disease (SVD), including lacunar infarctions, white matter lesions and cerebral microbleeds, has been shown to be associated not only with stroke incidence, but also with the development and progression of dementia and diabetic microangiopathy. However, the pathogenesis of cerebral SVD is not fully understood. In addition, data on the association between neuroimaging findings of the cerebral SVD and diabetes are limited. Recently, the clinical importance of the link between cerebral SVD and retinal microvascular abnormalities has been a topic of considerable interest. Several clinical studies have shown that retinal microvascular abnormalities are closely related to cerebral SVD, suggesting that retinal microvascular abnormalities might be pathophysiologically linked to ischemic cerebral SVD. We review the literature relating to the pathophysiology and neuroimaging of cerebrovascular disease in diabetes, and discuss the problems based on the concept of cerebral large and small vessel disease. © 2016 The Authors. Journal of Diabetes Investigation published by Asian Association for the Study of Diabetes (AASD) and John Wiley & Sons Australia, Ltd.

Reversibility of retinal microvascular changes in severe falciparum malaria.

PubMed

Maude, Richard J; Kingston, Hugh W F; Joshi, Sonia; Mohanty, Sanjib; Mishra, Saroj K; White, Nicholas J; Dondorp, Arjen M

2014-09-01

Malarial retinopathy allows detailed study of central nervous system vascular pathology in living patients with severe malaria. An adult with cerebral malaria is described who had prominent retinal whitening with corresponding retinal microvascular obstruction, vessel dilatation, increased vascular tortuosity, and blood retinal barrier leakage with decreased visual acuity, all of which resolved on recovery. Additional study of these features and their potential role in elucidating the pathogenesis of cerebral malaria is warranted. © The American Society of Tropical Medicine and Hygiene.

Relationship between retinal blood flow and arterial oxygen

PubMed Central

Cheng, Richard W.; Yusof, Firdaus; Tsui, Edmund; Jong, Monica; Duffin, James; Flanagan, John G.; Fisher, Joseph A.

2016-01-01

Key points Vascular reactivity, the response of the vessels to a vasoactive stimulus such as hypoxia and hyperoxia, can be used to assess the vascular range of adjustment in which the vessels are able to compensate for changes in PO2.Previous studies in the retina have not accurately quantified retinal vascular responses and precisely targeted multiple PaO2 stimuli at the same time as controlling the level of carbon dioxide, thus precluding them from modelling the relationship between retinal blood flow and oxygen.The present study modelled the relationship between retinal blood flow and PaO2, showing them to be a combined linear and hyperbolic function.This model demonstrates that the resting tonus of the vessels is at the mid‐point and that they have great vascular range of adjustment, compensating for decreases in oxygen above a P ETC O2 of 32–37 mmHg but being limited below this threshold. Abstract Retinal blood flow (RBF) increases in response to a reduction in oxygen (hypoxia) but decreases in response to increased oxygen (hyperoxia). However, the relationship between blood flow and the arterial partial pressure of oxygen has not been quantified and modelled in the retina, particularly in the vascular reserve and resting tonus of the vessels. The present study aimed to determine the limitations of the retinal vasculature by modelling the relationship between RBF and oxygen. Retinal vascular responses were measured in 13 subjects for eight different blood gas conditions, with the end‐tidal partial pressure of oxygen (P ETC O2) ranging from 40–500 mmHg. Retinal vascular response measurements were repeated twice; using the Canon laser blood flowmeter (Canon Inc., Tokyo, Japan) during the first visit and using Doppler spectral domain optical coherence tomography during the second visit. We determined that the relationship between RBF and PaO2 can be modelled as a combination of hyperbolic and linear functions. We concluded that RBF compensated for decreases in arterial oxygen content for all stages of hypoxia used in the present study but can no longer compensate below a P ETC O2 of 32–37 mmHg. These vessels have a great vascular range of adjustment, increasing diameter (8.5% arteriolar and 21% total venous area) with hypoxia (40 mmHg P ETC O2; P < 0.001) and decreasing diameter (6.9% arteriolar and 23% total venous area) with hyperoxia (500 mmHg P ETC O2; P < 0.001) to the same extent. This indicates that the resting tonus is near the mid‐point of the adjustment ranges at resting PaO2 where sensitivity is maximum. PMID:26607393

Relationship between retinal blood flow and arterial oxygen.

PubMed

Cheng, Richard W; Yusof, Firdaus; Tsui, Edmund; Jong, Monica; Duffin, James; Flanagan, John G; Fisher, Joseph A; Hudson, Chris

2016-02-01

Vascular reactivity, the response of the vessels to a vasoactive stimulus such as hypoxia and hyperoxia, can be used to assess the vascular range of adjustment in which the vessels are able to compensate for changes in PO2. Previous studies in the retina have not accurately quantified retinal vascular responses and precisely targeted multiple PaO2 stimuli at the same time as controlling the level of carbon dioxide, thus precluding them from modelling the relationship between retinal blood flow and oxygen. The present study modelled the relationship between retinal blood flow and PaO2, showing them to be a combined linear and hyperbolic function. This model demonstrates that the resting tonus of the vessels is at the mid-point and that they have great vascular range of adjustment, compensating for decreases in oxygen above a PETCO2 of 32-37 mmHg but being limited below this threshold. Retinal blood flow (RBF) increases in response to a reduction in oxygen (hypoxia) but decreases in response to increased oxygen (hyperoxia). However, the relationship between blood flow and the arterial partial pressure of oxygen has not been quantified and modelled in the retina, particularly in the vascular reserve and resting tonus of the vessels. The present study aimed to determine the limitations of the retinal vasculature by modelling the relationship between RBF and oxygen. Retinal vascular responses were measured in 13 subjects for eight different blood gas conditions, with the end-tidal partial pressure of oxygen (PETCO2) ranging from 40-500 mmHg. Retinal vascular response measurements were repeated twice; using the Canon laser blood flowmeter (Canon Inc., Tokyo, Japan) during the first visit and using Doppler spectral domain optical coherence tomography during the second visit. We determined that the relationship between RBF and PaO2 can be modelled as a combination of hyperbolic and linear functions. We concluded that RBF compensated for decreases in arterial oxygen content for all stages of hypoxia used in the present study but can no longer compensate below a PETCO2 of 32-37 mmHg. These vessels have a great vascular range of adjustment, increasing diameter (8.5% arteriolar and 21% total venous area) with hypoxia (40 mmHg P ETC O2; P < 0.001) and decreasing diameter (6.9% arteriolar and 23% total venous area) with hyperoxia (500 mmHg PETCO2; P < 0.001) to the same extent. This indicates that the resting tonus is near the mid-point of the adjustment ranges at resting PaO2 where sensitivity is maximum. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

Wavelength dependence of the apparent diameter of retinal blood vessels

NASA Astrophysics Data System (ADS)

Park, Robert; Twietmeyer, Karen; Chipman, Russell; Beaudry, Neil; Salyer, David

2005-04-01

Imaging of retinal blood vessels may assist in the diagnosis and monitoring of diseases such as glaucoma, diabetic retinopathy, and hypertension. However, close examination reveals that the contrast and apparent diameter of vessels are dependent on the wavelength of the illuminating light. In this study multispectral images of large arteries and veins within enucleated swine eyes are obtained with a modified fundus camera by use of intravitreal illumination. The diameters of selected vessels are measured as a function of wavelength by cross-sectional analysis. A fixed scale with spectrally independent dimension is placed above the retina to isolate the chromatic effects of the imaging system and eye. Significant apparent differences between arterial and venous diameters are found, with larger diameters observed at shorter wavelengths. These differences are due primarily to spectral absorption in the cylindrical blood column.

EFFECTS OF INTRAVITREAL RANIBIZUMAB AND BEVACIZUMAB ON THE RETINAL VESSEL SIZE IN DIABETIC MACULAR EDEMA.

PubMed

Kurt, Muhammed Mustafa; Çekiç, Osman; Akpolat, Çetin; Elçioglu, Mustafa

2018-06-01

The goal of this study was to assess the effects of a single injection of intravitreal ranibizumab (RAN) or bevacizumab (BEV) on the retinal vessel size in eyes with diabetic macular edema. In total, 32 patients were enrolled in the RAN group, and 30 patients were included in BEV group. Each of these groups was also subdivided into two others groups: a study group and a control group. The study groups were composed of the injected eyes, whereas the noninjected fellow eyes served as the control groups. The patients underwent complete ophthalmic examinations, including optical coherence tomography and fundus fluorescein angiography, and the primary outcome measures included the central retinal artery equivalent, central retinal vein equivalent, and artery-to-vein ratio. In the RAN study group (n = 32), the preinjection mean central retinal artery equivalent (175.42 μm) decreased to 169.01 μm after 1 week, and to 167.47 μm after 1 month (P < 0.001), whereas the baseline central retinal vein equivalent (235.29 μm) decreased initially to 219.90 μm after 1 week, and to 218.36 μm after 1 month (P < 0.001). In the BEV study group (n = 30), the preinjection central retinal artery equivalent (150.21 μm) decreased to 146.25 μm after 1 week, and to 145.89 μm after 1 month (P < 0.001); whereas the baseline central retinal vein equivalent (211.87 μm) decreased initially to 204.59 μm after 1 week and was 205.24 μm after 1 month (P < 0.001). The preinjection artery-to-vein ratio values changed significantly (P = 0.001) after 1 week and after 1 month in the RAN group, but no significant alteration in the artery-to-vein ratio was observed in the BEV group (P = 0.433). In both the RAN (n = 32) and BEV (n = 30) control groups, none of the 3 parameters changed throughout the study period, when compared with the baseline. The results of this study showed that both RAN and BEV injections significantly constricted the retinal blood vessel diameters.

Bone marrow–derived stem cells preserve cone vision in retinitis pigmentosa

PubMed Central

Smith, Lois E.H.

2004-01-01

Retinitis pigmentosa is a heritable group of blinding diseases resulting from loss of photoreceptors, primarily rods and secondarily cones, that mediate central vision. Loss of retinal vasculature is a presumed metabolic consequence of photoreceptor degeneration. A new study shows that autologous bone marrow–derived lineage-negative hematopoietic stem cells, which incorporate into the degenerating blood vessels in two murine models of retinitis pigmentosa, rd1 and rd10, prevent cone loss. The use of autologous bone marrow might avoid problems with rejection while preserving central cone vision in a wide variety of genetically disparate retinal degenerative diseases. PMID:15372096

Quantification of rat retinal growth and vascular population changes after single and split doses of proton irradiation: translational study using stereology methods

NASA Technical Reports Server (NTRS)

Mao, Xiao W.; Archambeau, John O.; Kubinova, Lucie; Boyle, Soames; Petersen, Georgia; Grove, Roger; Nelson, G. A. (Principal Investigator)

2003-01-01

This study quantified architectural and population changes in the rat retinal vasculature after proton irradiation using stereology. A 100 MeV conformal proton beam delivered 8, 14, 20 and 28 Gy as single and split doses to the whole eye. The vascular networks were prepared from retinal digests. Stereological methods were used to obtain the area of the retina and unbiased estimates of microvessel/artery/vein endothelial, pericyte and smooth muscle population, and vessel length. The retinal area increased progressively in the unirradiated, age-matched controls and in the retinas irradiated with 8 and 14 Gy, indicating uniform progressive retinal growth. No growth occurred after 20 and 28 Gy. Regression analysis of total endothelial cell number in all vessels (arteries, veins and capillaries) after irradiation documented a progressive time- and dose-dependent cell loss occurring over 15 to 24 months. The difference from controls was significant (P<0.01) after 28 Gy given in single and split doses and after 20 Gy given as a split dose (P<0.05). Total vessel length in microvessel was significantly shortened at 20 and 28 Gy compared to that of controls (P<0.05). No evident dose recovery was observed in the endothelial populations after split doses. At 10 Gy, the rate of endothelial cell loss, a dose parameter used to characterize the time- and dose-dependent loss of the endothelial population, was doubled.

Hyperspectral Computed Tomographic Imaging Spectroscopy of Vascular Oxygen Gradients in the Rabbit Retina In Vivo

PubMed Central

Kashani, Amir H.; Kirkman, Erlinda; Martin, Gabriel; Humayun, Mark S.

2011-01-01

Diagnosis of retinal vascular diseases depends on ophthalmoscopic findings that most often occur after severe visual loss (as in vein occlusions) or chronic changes that are irreversible (as in diabetic retinopathy). Despite recent advances, diagnostic imaging currently reveals very little about the vascular function and local oxygen delivery. One potentially useful measure of vascular function is measurement of hemoglobin oxygen content. In this paper, we demonstrate a novel method of accurately, rapidly and easily measuring oxygen saturation within retinal vessels using in vivo imaging spectroscopy. This method uses a commercially available fundus camera coupled to two-dimensional diffracting optics that scatter the incident light onto a focal plane array in a calibrated pattern. Computed tomographic algorithms are used to reconstruct the diffracted spectral patterns into wavelength components of the original image. In this paper the spectral components of oxy- and deoxyhemoglobin are analyzed from the vessels within the image. Up to 76 spectral measurements can be made in only a few milliseconds and used to quantify the oxygen saturation within the retinal vessels over a 10–15 degree field. The method described here can acquire 10-fold more spectral data in much less time than conventional oximetry systems (while utilizing the commonly accepted fundus camera platform). Application of this method to animal models of retinal vascular disease and clinical subjects will provide useful and novel information about retinal vascular disease and physiology. PMID:21931729

The Role of Retinal Vascular Density as a Screening Tool for Ageing and Stroke.

PubMed

Sprödhuber, Andrea; Wolz, Johannes; Budai, Attila; Laumeier, Inga; Audebert, Heinrich J; Michelson, Georg

2018-06-06

To measure the density of retinal vessels from digitized fundus photographs in patients with recent stroke and age-matched controls. To investigate whether the parameter retinal vascular density (RVD) served as a quantitative marker for cerebrovascular events. Digitized fundus photographs of n = 158 subjects with stroke or transient ischemic attack within 1 year at the time of examination and n = 1,250 age-matched controls without any remarkable medical history were examined. Sex, hypertension, and diabetes were considered to be cofactors. Measurement of RVD was performed with a computer-aided image-analyzing program by segmenting automatically all visible retinal vessels and measuring areas of vessels in distinct circles around the optic disk. In controls RVD dwindles with increasing distance from the optic disk. RVD decreased significantly with age (p = 0.000). Stroke patients showed significantly lower values of RVD of -15% in comparison to age-matched controls. In old subjects, stroke in combination with hypertension is associated with a significant decreased RVD, and in middle-aged subjects diabetes and stroke are associated with a significant decreased RVD (p = 0.01). Age and stroke are significant risk factors for decreased RVD. Diabetes and arterial hypertension are additional significant risk factors in patients with stroke with respect to RVD. © 2018 S. Karger AG, Basel.

Modulation of Retinal Arteriolar Central Reflection by APOE Genotype.

PubMed

Frost, Shaun; Bhuiyan, Alauddin; Offerman, David; Doecke, James D; Macaulay, S Lance; Sohrabi, Hamid R; Ames, David; Masters, Colin; Martins, Ralph N; Kanagasingam, Yogesan; Group, Aibl Research

2017-01-01

This study investigated the retinal arteriolar central reflex (CR, the central reflection observed in photographs of retinal vessels), which may provide information about micro-vascular health in the retina and also the brain, due to the homology between these vascular networks. The study also describes a novel computer based semi-automated technique that accurately quantifies retinal arteriolar CR and vessel width, and calculates the CR to vessel width ratio (CRR) from digital retinal photographs. Digital retinal photographs were collected from participants in the Australian Imaging, Biomarkers and Lifestyle study of ageing (AIBL), including 25 participants diagnosed with Alzheimer's disease (AD) (age 72.4 ± 7.5 yrs, 12 male, 13 female) and 123 elderly participants without dementia (cognitively normals: CN) (age 71.6 ± 5.6 yrs, 55 male, 68 female). Using a sub-cohort of 144 (22 AD, 122 CN) with the novel CRR measures, we identified significantly higher CRR levels in AD participants (mean CRR 0.253 (SD 0.04)) as compared with CN's (mean CRR 0.231 (SD 0.04), p = 0.025). Adjustment for APOE ε4 allele status however, reduced the significance (p = 0.081). CRR was significantly higher in APOE ε4 allele carriers (mean CRR 0.254 (SD 0.03) as compared with non-carriers (mean CRR 0.224 (SD 0.05), p < 0.0001). These data indicate that CRR is strongly linked to APOE ε4 status and exhibits a weaker, independent trend with AD diagnosis. The retina may be useful as a novel model for non-invasive monitoring of the effects of APOE ε4 on the central nervous system, particularly in cerebrovascular disease. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Alk2/ACVR1 and Alk3/BMPR1A Provide Essential Function for Bone Morphogenetic Protein-Induced Retinal Angiogenesis.

PubMed

Lee, Heon-Woo; Chong, Diana C; Ola, Roxana; Dunworth, William P; Meadows, Stryder; Ka, Jun; Kaartinen, Vesa M; Qyang, Yibing; Cleaver, Ondine; Bautch, Victoria L; Eichmann, Anne; Jin, Suk-Won

2017-04-01

Increasing evidence suggests that bone morphogenetic protein (BMP) signaling regulates angiogenesis. Here, we aimed to define the function of BMP receptors in regulating early postnatal angiogenesis by analysis of inducible, endothelial-specific deletion of the BMP receptor components Bmpr2 (BMP type 2 receptor), Alk1 (activin receptor-like kinase 1), Alk2 , and Alk3 in mouse retinal vessels. Expression analysis of several BMP ligands showed that proangiogenic BMP ligands are highly expressed in postnatal retinas. Consistently, BMP receptors are also strongly expressed in retina with a distinct pattern. To assess the function of BMP signaling in retinal angiogenesis, we first generated mice carrying an endothelial-specific inducible deletion of Bmpr2 . Postnatal deletion of Bmpr2 in endothelial cells substantially decreased the number of angiogenic sprouts at the vascular front and branch points behind the front, leading to attenuated radial expansion. To identify critical BMPR1s (BMP type 1 receptors) associated with BMPR2 in retinal angiogenesis, we generated endothelial-specific inducible deletion of 3 BMPR1s abundantly expressed in endothelial cells and analyzed the respective phenotypes. Among these, endothelial-specific deletion of either Alk2 / acvr1 or Alk3 / Bmpr1a caused a delay in radial expansion, reminiscent of vascular defects associated with postnatal endothelial-specific deletion of BMPR2, suggesting that ALK2/ACVR1 and ALK3/BMPR1A are likely to be the critical BMPR1s necessary for proangiogenic BMP signaling in retinal vessels. Our data identify BMP signaling mediated by coordination of ALK2/ACVR1, ALK3/BMPR1A, and BMPR2 as an essential proangiogenic cue for retinal vessels. © 2017 The Authors.

Alk2/ACVR1 and Alk3/BMPR1A Provide Essential Function for Bone Morphogenetic Protein Induced Retinal Angiogenesis

PubMed Central

Lee, Heon-Woo; Chong, Diana C.; Ola, Roxana; Dunworth, William P.; Meadows, Stryder; Ka, Jun; Kaartinen, Vesa M.; Qyang, Yibing; Cleaver, Ondine; Bautch, Victoria L.; Eichmann, Anne; Jin, Suk-Won

2017-01-01

Objective Increasing evidence suggests that Bone Morphogenetic Protein (BMP) signaling regulates angiogenesis. Here, we aimed to define the function of BMP receptors in regulating early post-natal angiogenesis by analysis of inducible, endothelial specific deletion of the BMP receptor components Bmpr2, Alk1, Alk2 and Alk3 in mouse retinal vessels. Approach and Results Expression analysis of several BMP ligands showed that pro-angiogenic BMP ligands are highly expressed in postnatal retinas. Consistently, BMP receptors are also strongly expressed in retina with a distinct pattern. To assess the function of BMP signaling in retinal angiogenesis, we first generated mice carrying an endothelial-specific inducible deletion of BMP Type 2 receptor (Bmpr2). Postnatal deletion of Bmpr2 in endothelial cells substantially decreased the number of angiogenic sprouts at the vascular front and branchpoints behind the front, leading to attenuated radial expansion. To identify critical BMPR1s associated with BMPR2 in retinal angiogenesis, we generated endothelial-specific inducible deletion of three BMPR1s abundantly expressed in endothelial cells and analyzed the respective phenotypes. Among these, endothelial specific deletion of either Alk2/acvr1 or Alk3/Bmpr1a caused a delay in radial expansion, reminiscent of vascular defects associated with postnatal endothelial specific deletion of BMPR2, suggesting that ALK2/ACVR1 and ALK3/BMPR1A are likely to be the critical BMPR1s necessary for pro-angiogenic BMP signaling in retinal vessels. Conclusions Our data identify BMP signaling mediated by coordination of ALK2/ACVR1, ALK3/BMPR1A, and BMPR2 as an essential pro-angiogenic cue for retinal vessels. PMID:28232325

The anti-ALS drug riluzole attenuates pericyte loss in the diabetic retinopathy of streptozotocin-treated mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Jeong A.

Loss of pericytes, considered an early hallmark of diabetic retinopathy, is thought to involve abnormal activation of protein kinase C (PKC). We previously showed that the anti-amyotrophic lateral sclerosis (ALS) drug riluzole functions as a PKC inhibitor. Here, we examined the effects of riluzole on pathological changes in diabetic retinopathy. Pathological endpoints examined in vivo included the number of pericytes and integrity of retinal vessels in streptozotocin (STZ)-induced diabetic mice. In addition, PKC activation and the induction of monocyte chemotactic protein (MCP1) were assessed in diabetic mice and in human retinal pericytes exposed to advanced glycation end product (AGE) ormore » modified low-density lipoprotein (mLDL). The diameter of retinal vessels and the number of pericytes were severely reduced, and the levels of MCP1 and PKC were increased in STZ-induced diabetic mice. Administration of riluzole reversed all of these changes. Furthermore, the increased expression of MCP1 in AGE- or mLDL-treated cultured retinal pericytes was inhibited by treatment with riluzole or the PKC inhibitor GF109203X. In silico modeling showed that riluzole fits well within the catalytic pocket of PKC. Taken together, our results demonstrate that riluzole attenuates both MCP1 induction and pericyte loss in diabetic retinopathy, likely through its direct inhibitory effect on PKC. - Highlights: • The effects of riluzole were examined in streptozotocin-induced diabetic mice. • The diameter of retinal vessels and the number of pericytes were severely reduced. • The levels of MCP1 and PKC were increased, while riluzole reversed all changes. • Riluzole attenuated the level of MCP1 in AGE- or mLDL-treated retinal pericytes. • Riluzole attenuated both MCP1 induction and pericyte loss in diabetic retinopathy.« less

Retinal vascular segmentation using superpixel-based line operator and its application to vascular topology estimation.

PubMed

Na, Tong; Xie, Jianyang; Zhao, Yitian; Zhao, Yifan; Liu, Yue; Wang, Yongtian; Liu, Jiang

2018-05-09

Automatic methods of analyzing of retinal vascular networks, such as retinal blood vessel detection, vascular network topology estimation, and arteries/veins classification are of great assistance to the ophthalmologist in terms of diagnosis and treatment of a wide spectrum of diseases. We propose a new framework for precisely segmenting retinal vasculatures, constructing retinal vascular network topology, and separating the arteries and veins. A nonlocal total variation inspired Retinex model is employed to remove the image intensity inhomogeneities and relatively poor contrast. For better generalizability and segmentation performance, a superpixel-based line operator is proposed as to distinguish between lines and the edges, thus allowing more tolerance in the position of the respective contours. The concept of dominant sets clustering is adopted to estimate retinal vessel topology and classify the vessel network into arteries and veins. The proposed segmentation method yields competitive results on three public data sets (STARE, DRIVE, and IOSTAR), and it has superior performance when compared with unsupervised segmentation methods, with accuracy of 0.954, 0.957, and 0.964, respectively. The topology estimation approach has been applied to five public databases (DRIVE,STARE, INSPIRE, IOSTAR, and VICAVR) and achieved high accuracy of 0.830, 0.910, 0.915, 0.928, and 0.889, respectively. The accuracies of arteries/veins classification based on the estimated vascular topology on three public databases (INSPIRE, DRIVE and VICAVR) are 0.90.9, 0.910, and 0.907, respectively. The experimental results show that the proposed framework has effectively addressed crossover problem, a bottleneck issue in segmentation and vascular topology reconstruction. The vascular topology information significantly improves the accuracy on arteries/veins classification. © 2018 American Association of Physicists in Medicine.

The peptidomimetic Vasotide targets two retinal VEGF receptors and reduces pathological angiogenesis in murine and nonhuman primate models of retinal disease

PubMed Central

Sidman, Richard L.; Li, Jianxue; Lawrence, Matthew; Hu, Wenzheng; Musso, Gary F.; Giordano, Ricardo J.; Cardó-Vila, Marina; Pasqualini, Renata; Arap, Wadih

2016-01-01

Blood vessel growth from preexisting vessels (angiogenesis) underlies many severe diseases including major blinding retinal diseases such as retinopathy of prematurity (ROP) and aged macular degeneration (AMD). This observation has driven development of antibody inhibitors that block a central factor in AMD, named vascular endothelial growth factor (VEGF), from binding to its receptors VEGFR-1 and VEGFR-2. However, some patients are insensitive to current anti-VEGF drugs or develop resistance, and the required repeated intravitreal injection of these large molecules is costly and clinically problematic. Here, we have evaluated a small cyclic retro-inverted peptidomimetic, D(Cys-Leu-Pro-Arg-Cys), abbreviated as D(CLPRC), and hereafter named Vasotide, that inhibits retinal angiogenesis by binding selectively to the VEGF receptors, VEGFR-1 and Neuropilin-1 (NRP-1). Delivery of Vasotide in eye drops or via intraperitoneal injection in a laser-induced monkey model of human wet AMD, a mouse genetic knockout model of the AMD subtype called retinal angiomatous proliferation (RAP), and a mouse oxygen-induced model of retinopathy of prematurity (ROP) markedly decreased retinal angiogenesis in all three animal models. This prototype drug candidate is a promising new dual receptor inhibitor of the VEGF ligand with potential for translation into safer, less invasive applications to combat pathological angiogenesis in retinal disorders. PMID:26468327

Retinal Vessel Oxygen Saturation during 100% Oxygen Breathing in Healthy Individuals

PubMed Central

Olafsdottir, Olof Birna; Eliasdottir, Thorunn Scheving; Kristjansdottir, Jona Valgerdur; Hardarson, Sveinn Hakon; Stefánsson, Einar

2015-01-01

Purpose To detect how systemic hyperoxia affects oxygen saturation in retinal arterioles and venules in healthy individuals. Methods Retinal vessel oxygen saturation was measured in 30 healthy individuals with a spectrophotometric retinal oximeter (Oxymap T1). Oximetry was performed during breathing of room air, 100% oxygen (10 minutes, 6L/min) and then again room air (10 minutes recovery). Results Mean oxygen saturation rises modestly in retinal arterioles during 100% oxygen breathing (94.5%±3.8 vs. 92.0%±3.7% at baseline, p<0.0001) and dramatically in retinal venules (76.2%±8.0% vs. 51.3%±5.6%, p<0.0001). The arteriovenous difference decreased during 100% oxygen breathing (18.3%±9.0% vs. 40.7%±5.7%, p<0.0001). The mean diameter of arterioles decreased during 100% oxygen breathing compared to baseline (9.7±1.4 pixels vs. 10.3±1.3 pixels, p<0.0001) and the same applies to the mean venular diameter (11.4±1.2 pixels vs. 13.3±1.5 pixels, p<0.0001). Conclusions Breathing 100% oxygen increases oxygen saturation in retinal arterioles and more so in venules and constricts them compared to baseline levels. The dramatic increase in oxygen saturation in venules reflects oxygen flow from the choroid and the unusual vascular anatomy and oxygen physiology of the eye. PMID:26042732

Evaluation of the Retinal Vasculature in Hypertension and Chronic Kidney Disease in an Elderly Population of Irish Nuns.

PubMed

McGowan, Amy; Silvestri, Giuliana; Moore, Evelyn; Silvestri, Vittorio; Patterson, Christopher C; Maxwell, Alexander P; McKay, Gareth J

2015-01-01

Chronic kidney disease (CKD) and hypertension are global public health problems associated with considerable morbidity, premature mortality and attendant healthcare costs. Previous studies have highlighted that non-invasive examination of the retinal microcirculation can detect microvascular pathology that is associated with systemic disorders of the circulatory system such as hypertension. We examined the associations between retinal vessel caliber (RVC) and fractal dimension (DF), with both hypertension and CKD in elderly Irish nuns. Data from 1233 participants in the cross-sectional observational Irish Nun Eye Study (INES) were assessed from digital photographs with a standardized protocol using computer-assisted software. Multivariate regression analyses were used to assess associations with hypertension and CKD, with adjustment for age, body mass index (BMI), refraction, fellow eye RVC, smoking, alcohol consumption, ischemic heart disease (IHD), cerebrovascular accident (CVA), diabetes and medication use. In total, 1122 (91%) participants (mean age: 76.3 [range: 56-100] years) had gradable retinal images of sufficient quality for blood vessel assessment. Hypertension was significantly associated with a narrower central retinal arteriolar equivalent (CRAE) in a fully adjusted analysis (P = 0.002; effect size = -2.16 μm; 95% confidence intervals [CI]: -3.51, -0.81 μm). No significant associations between other retinal vascular parameters and hypertension or between any retinal vascular parameters and CKD were found. Individuals with hypertension have significantly narrower retinal arterioles which may afford an earlier opportunity for tailored prevention and treatment options to optimize the structure and function of the microvasculature, providing additional clinical utility. No significant associations between retinal vascular parameters and CKD were detected.

Cardiovascular risk factors and retinal microvascular signs in an adult Japanese population: the Funagata Study.

PubMed

Kawasaki, Ryo; Wang, Jie Jin; Rochtchina, Elena; Taylor, Bronwen; Wong, Tien Yin; Tominaga, Makoto; Kato, Takeo; Daimon, Makoto; Oizumi, Toshihide; Kawata, Sumio; Kayama, Takamasa; Yamashita, Hidetoshi; Mitchell, Paul

2006-08-01

To describe the prevalence of retinal vascular signs and their association with cardiovascular risk factors in a Japanese population. Population-based cross-sectional study. Adult persons aged 35 years or older from Funagata, Yamagata Prefecture, Japan (n = 1481). The Funagata Study is a Japanese population-based study of persons aged 35 years or older, and included 1961 nondiabetic participants (53.3% of 3676 eligible subjects). A nonmydriatic retinal photograph was taken of 1 eye to assess retinal microvascular signs. Retinal arteriolar wall signs (focal arteriolar narrowing, arteriovenous nicking, enhanced arteriolar wall reflex) and retinopathy were assessed in 1481 participants without diabetes (40.3% of eligible persons) using a standardized protocol. Using a computer-assisted method, retinal vessel diameters were measured in 921 participants with gradable retinal image (25.1% of eligible persons). Prevalence of retinal microvascular signs and their association with cardiovascular risk factors. Moderate or severe focal arteriolar narrowing, arteriovenous nicking, enhanced arteriolar wall reflex, and retinopathy were found in 8.3%, 15.2%, 18.7%, and 9.0%, respectively, of the study population. Mean (+/-standard error) values for retinal arteriolar diameter were 178.6+/-21.0 mum, and mean values (+/-standard error) for venular diameter were 214.9+/-20.6 mum. Older persons were more likely to have retinal arteriolar wall signs, retinopathy, and narrower retinal vessel diameters. After adjusting for multiple factors, each 10-mmHg increase in mean arterial blood pressure was associated with a 20% to 40% increased likelihood of retinal arteriolar signs and a 2.8-mum reduction in arteriolar diameter. Retinopathy was associated with higher body mass index and both impaired glucose tolerance and impaired fasting glucose. In nondiabetic Japanese adults, retinal arteriolar wall signs were associated with older age and increased blood pressure, whereas retinopathy was associated with older age, higher body mass index, impaired glucose tolerance, and impaired fasting glucose. These findings are comparable with data from white populations.

Evaluation of macular and peripapillary vessel flow density in eyes with no known pathology using optical coherence tomography angiography.

PubMed

Hassan, Muhammad; Sadiq, Mohammad Ali; Halim, Muhammad Sohail; Afridi, Rubbia; Soliman, Mohamed K; Sarwar, Salman; Agarwal, Aniruddha; Do, Diana V; Nguyen, Quan Dong; Sepah, Yasir Jamal

2017-01-01

To assess normal vessel flow density (VFD) in macular and peripapillary regions of eyes with no known ocular pathology using optical coherence tomography angiography (OCTA). AngioVue (Optovue, Fremont, CA, USA) was used to capture OCTA images. A 3 × 3 mm grid and a 4.5 × 4.5 mm grid was used to scan parafoveal and peripapillary regions, respectively. ReVue software was utilized to measure VFD in five sectors within the inner two circles of ETDRS grid in macular region and correlated to retinal thickness of same sectors. At optic disc, VFD was calculated in six sectors based on Garway-Heath map. Area and morphology of foveal avascular zone (FAZ) was correlated with VFD in central 1 mm. The influence of myopia on mean VFD was also assessed. Twenty-four eyes (mean age: 30 years) were analyzed. Mean VFD in macular sectors was 43.5 (±4.5) and 45.8 (±5.0) % in superficial and deep retinal plexuses, respectively. Mean VFD was significantly higher in deep retinal plexus compared to superficial retinal plexus in all sectors except central 1 mm (p < 0.05). Mean VFD in central 1 mm increases with an increase in central retinal thickness in both superficial and deep retinal plexuses (p < 0.001). Mean parafoveal VFD at level of both superficial and deep retinal plexuses decrease with an increase in spherical equivalent in myopics (p < 0.05). Mean VFD in myopics was found to be significantly lower in parafoveal region of deep retinal plexus (p < 0.05). Mean area of FAZ was 0.33 (±0.15) and 0.47 mm 2 (±0.15) in superficial and deep retinal plexuses, respectively. Area of FAZ decreases with an increase in central 1 mm thickness and foveal VFD (p < 0.001). OCTA may be used to measure VFD in macular and peripapillary regions. Vessels in the parafoveal region are more densely packed in the deep retinal plexus leading to higher VFD compared to superficial plexus. Thicker retina in fovea translates into higher foveal VFD due to more compact arrangement of retinal layers and continuity of inner nuclear layer (INL). Myopia is associated with lower VFD in parafoveal region at level of deep retinal plexuses which may explain thinning of INL in myopics.

E2f1 mediates high glucose-induced neuronal death in cultured mouse retinal explants.

PubMed

Wang, Yujiao; Zhou, Yi; Xiao, Lirong; Zheng, Shijie; Yan, Naihong; Chen, Danian

2017-10-02

Diabetic retinopathy (DR) is the most common complication of diabetes and remains one of the major causes of blindness in the world; infants born to diabetic mothers have higher risk of developing retinopathy of prematurity (ROP). While hyperglycemia is a major risk factor, the molecular and cellular mechanisms underlying DR and diabetic ROP are poorly understood. To explore the consequences of retinal cells under high glucose, we cultured wild type or E2f1 -/- mouse retinal explants from postnatal day 8 with normal glucose, high osmotic or high glucose media. Explants were also incubated with cobalt chloride (CoCl 2 ) to mimic the hypoxic condition. We showed that, at 7 days post exposure to high glucose, retinal explants displayed elevated cell death, ectopic cell division and intact retinal vascular plexus. Cell death mainly occurred in excitatory neurons, such as ganglion and bipolar cells, which were also ectopically dividing. Many Müller glial cells reentered the cell cycle; some had irregular morphology or migrated to other layers. High glucose inhibited the hyperoxia-induced blood vessel regression of retinal explants. Moreover, inactivation of E2f1 rescued high glucose-induced ectopic division and cell death of retinal neurons, but not ectopic cell division of Müller glial cells and vascular phenotypes. This suggests that high glucose has direct but distinct effects on retinal neurons, glial cells and blood vessels, and that E2f1 mediates its effects on retinal neurons. These findings shed new light onto mechanisms of DR and the fetal retinal abnormalities associated with maternal diabetes, and suggest possible new therapeutic strategies.

Identification of endogenous flurophores in the layered retina

NASA Astrophysics Data System (ADS)

Xu, Gaixia; Chen, Danni; Sun, Yiwen; Qu, Junle; Lin, Ziyang; Ding, Zhihua; Niu, Hanben

2007-05-01

In this paper, we measured and analyzed the characteristic of endogenous fluorophores in porcine layered retina by using advanced fluorescence spectroscopy and microscopy imaging technology. It was found that there were obvious contrasts corresponding to the different layers of retina, which may be important for fundus disease diagnosis. The retinal pigment epithelium cells exhibited strong autofluorescence with as emission peak of 600+/-10nm when excited with 860-nm light. The emission peak of photoreceptors was at 652+/-5nm, and the emission peak of retinal vessels layer was weak and at 640~700nm, when excited with 488-nm light. Autofluorescence images of three layers of retina were obtained using the same setup. We concluded that the main endogenous fluorophore in PRE was lipofuscin and that in retinal vessels was porphyrin. What's more, the FMHW (full width at half. maximum) of retinal fluorescence spectrum was broad, which suggested that there wasn't only one endogenous fluorophores of tissues excited.

Smartphone-Based Accurate Analysis of Retinal Vasculature towards Point-of-Care Diagnostics

PubMed Central

Xu, Xiayu; Ding, Wenxiang; Wang, Xuemin; Cao, Ruofan; Zhang, Maiye; Lv, Peilin; Xu, Feng

2016-01-01

Retinal vasculature analysis is important for the early diagnostics of various eye and systemic diseases, making it a potentially useful biomarker, especially for resource-limited regions and countries. Here we developed a smartphone-based retinal image analysis system for point-of-care diagnostics that is able to load a fundus image, segment retinal vessels, analyze individual vessel width, and store or uplink results. The proposed system was not only evaluated on widely used public databases and compared with the state-of-the-art methods, but also validated on clinical images directly acquired with a smartphone. An Android app is also developed to facilitate on-site application of the proposed methods. Both visual assessment and quantitative assessment showed that the proposed methods achieved comparable results to the state-of-the-art methods that require high-standard workstations. The proposed system holds great potential for the early diagnostics of various diseases, such as diabetic retinopathy, for resource-limited regions and countries. PMID:27698369

Hypertensive retinopathy identification through retinal fundus image using backpropagation neural network

NASA Astrophysics Data System (ADS)

Syahputra, M. F.; Amalia, C.; Rahmat, R. F.; Abdullah, D.; Napitupulu, D.; Setiawan, M. I.; Albra, W.; Nurdin; Andayani, U.

2018-03-01

Hypertension or high blood pressure can cause damage of blood vessels in the retina of eye called hypertensive retinopathy (HR). In the event Hypertension, it will cause swelling blood vessels and a decrese in retina performance. To detect HR in patients body, it is usually performed through physical examination of opthalmoscope which is still conducted manually by an ophthalmologist. Certainly, in such a manual manner, takes a ong time for a doctor to detetct HR on aa patient based on retina fundus iamge. To overcome ths problem, a method is needed to identify the image of retinal fundus automatically. In this research, backpropagation neural network was used as a method for retinal fundus identification. The steps performed prior to identification were pre-processing (green channel, contrast limited adapative histogram qualization (CLAHE), morphological close, background exclusion, thresholding and connected component analysis), feature extraction using zoning. The results show that the proposed method is able to identify retinal fundus with an accuracy of 95% with maximum epoch of 1500.

Retinitis Pigmentosa Associated with Vasoproliferative Tumors and Coats-like Fundus

PubMed Central

Ghassemi, Fariba; Akbari-Kamrani, Marjan

2013-01-01

Purpose To report two cases of retinitis pigmentosa (RP) associated with vasoproliferative tumors (VPTs) and Coats-like fundus. Case Reports Two patients with RP presented with recent loss of vision due to combined VPTs and Coats-like retinal vascular alterations. One patient had two VPTs with adjacent capillary nonperfusion, telangiectasia and aneurysmal vascular changes in one eye. The other patient had prominent VPT with Coats-like retinal vascular alterations in both eyes. These lesions received treatment resulting in improved vision in both patients. Conclusion Although rare, VPTs and Coats-like retinal vascular alterations including retinal exudation associated with telangiectatic vessels, aneurysmal changes and capillary nonperfusion may occur in patients with RP. PMID:24349671

Patch-based automatic retinal vessel segmentation in global and local structural context.

PubMed

Cao, Shuoying; Bharath, Anil A; Parker, Kim H; Ng, Jeffrey

2012-01-01

In this paper, we extend our published work [1] and propose an automated system to segment retinal vessel bed in digital fundus images with enough adaptability to analyze images from fluorescein angiography. This approach takes into account both the global and local context and enables both vessel segmentation and microvascular centreline extraction. These tools should allow researchers and clinicians to estimate and assess vessel diameter, capillary blood volume and microvascular topology for early stage disease detection, monitoring and treatment. Global vessel bed segmentation is achieved by combining phase-invariant orientation fields with neighbourhood pixel intensities in a patch-based feature vector for supervised learning. This approach is evaluated against benchmarks on the DRIVE database [2]. Local microvascular centrelines within Regions-of-Interest (ROIs) are segmented by linking the phase-invariant orientation measures with phase-selective local structure features. Our global and local structural segmentation can be used to assess both pathological structural alterations and microemboli occurrence in non-invasive clinical settings in a longitudinal study.

Retinal changes in diabetic patients without diabetic retinopathy.

PubMed

Dumitrescu, Alina Gabriela; Istrate, Sinziana Luminita; Iancu, Raluca Claudia; Guta, Oana Maria; Ciuluvica, Radu; Voinea, Liliana

2017-01-01

The purpose of this study was to measure retinal vessel caliber and to examine early changes in macular thickness using optical coherence tomography (OCT). We evaluated to what extend vascular caliber and macular thickness differed between patients with type 2 diabetes mellitus without diabetic retinopathy compared with healthy individuals. 26 diabetic patients without diabetic retinopathy and 26 normal participants without any retinal and optic nerve diseases underwent ophthalmic examination, fundus photography, and OCT imaging. Temporal inferior retinal vessel diameters were measured using OCT. Also, we measured macular thickness in nine ETDRS subfields using Cirrus OCT. The mean age in the diabetic group was 61.5 years and in the control group, 55.5 years. Wider retinal arterioles and venules were found in patients with diabetes compared with healthy subjects (120 µm versus 96 µm, p<0.005 and 137 µm versus 120.5 µm, p value <0.001, respectively). In patients with type 2 diabetes mellitus, central macular thickness was significantly thinner than that of control eyes (243.5 µm versus 269.9 µm, p value <0.001). Our results support the hypothesis that the association between vascular damage and structural changes of the neuroretina is an early indicator of retinal impairment in patients with diabetes without diabetic retinopathy.

Retinal displacement toward optic disc after internal limiting membrane peeling for idiopathic macular hole.

PubMed

Ishida, Masahiro; Ichikawa, Yoshikazu; Higashida, Rieko; Tsutsumi, Yorihisa; Ishikawa, Atsushi; Imamura, Yutaka

2014-05-01

To examine the retinal displacement following successful macular hole (MH) surgery with internal limiting membrane (ILM) peeling and gas tamponade, and to determine the correlation between the extent of displacement and the basal MH size. Retrospective, interventional, observational case series. The medical records of consecutive patients with an idiopathic MH that had undergone vitrectomy with ILM peeling and gas tamponade were studied. The distances between the optic disc and the intersection of 2 retinal vessels located nasal or temporal to the fovea were measured manually preoperatively (A), and 2 weeks and 1, 3, 6, and 12 months postoperatively (B), on the fundus autofluorescence or near-infrared images. The basal and minimum diameters of the MHs were measured in the spectral-domain optical coherence tomographic images. The correlations between the ratio of the retinal displacement (A - B/A) and basal diameters of the MHs were determined. Twenty-one eyes of 21 patients (9 men, mean age: 64.6 ± 8.4 years) were studied. Ten eyes (47.6%) had stage 2 MH, 9 eyes (42.9%) had stage 3 MH, and 2 eyes (9.5%) had stage 4 MH. The temporal retinal vessels were displaced 260.8 ± 145.8 μm toward the optic disc at 2 weeks postoperatively, which was significantly greater than the 91.1 ± 89.7 μm of the nasal retinal vessels (paired t test, P < .001). The ratio of retinal displacement in the temporal field at 2 weeks was significantly correlated with the basal diameter of the MH (Spearman's rank correlation coeffieient = -0.476, P = .033. The greater displacement of the temporal retina than the nasal retina toward the optic disc postoperatively suggests that the temporal retina is more flexible and can be retracted toward the optic disc during the MH closure. Copyright © 2014 Elsevier Inc. All rights reserved.

Novel algorithm by low complexity filter on retinal vessel segmentation

NASA Astrophysics Data System (ADS)

Rostampour, Samad

2011-10-01

This article shows a new method to detect blood vessels in the retina by digital images. Retinal vessel segmentation is important for detection of side effect of diabetic disease, because diabetes can form new capillaries which are very brittle. The research has been done in two phases: preprocessing and processing. Preprocessing phase consists to apply a new filter that produces a suitable output. It shows vessels in dark color on white background and make a good difference between vessels and background. The complexity is very low and extra images are eliminated. The second phase is processing and used the method is called Bayesian. It is a built-in in supervision classification method. This method uses of mean and variance of intensity of pixels for calculate of probability. Finally Pixels of image are divided into two classes: vessels and background. Used images are related to the DRIVE database. After performing this operation, the calculation gives 95 percent of efficiency average. The method also was performed from an external sample DRIVE database which has retinopathy, and perfect result was obtained

Minimizing camera-eye optical aberrations during the 3D reconstruction of retinal structures

NASA Astrophysics Data System (ADS)

Aldana-Iuit, Javier; Martinez-Perez, M. Elena; Espinosa-Romero, Arturo; Diaz-Uribe, Rufino

2010-05-01

3D reconstruction of blood vessels is a powerful visualization tool for physicians, since it allows them to refer to qualitative representation of their subject of study. In this paper we propose a 3D reconstruction method of retinal vessels from fundus images. The reconstruction method propose herein uses images of the same retinal structure in epipolar geometry. Images are preprocessed by RISA system for segmenting blood vessels and obtaining feature points for correspondences. The correspondence points process is solved using correlation. The LMedS analysis and Graph Transformation Matching algorithm are used for outliers suppression. Camera projection matrices are computed with the normalized eight point algorithm. Finally, we retrieve 3D position of the retinal tree points by linear triangulation. In order to increase the power of visualization, 3D tree skeletons are represented by surfaces via generalized cylinders whose radius correspond to morphological measurements obtained by RISA. In this paper the complete calibration process including the fundus camera and the optical properties of the eye, the so called camera-eye system is proposed. On one hand, the internal parameters of the fundus camera are obtained by classical algorithms using a reference pattern. On the other hand, we minimize the undesirable efects of the aberrations induced by the eyeball optical system assuming that contact enlarging lens corrects astigmatism, spherical and coma aberrations are reduced changing the aperture size and eye refractive errors are suppressed adjusting camera focus during image acquisition. Evaluation of two self-calibration proposals and results of 3D blood vessel surface reconstruction are presented.

Optical Coherence Tomography Angiography Vessel Density in Healthy, Glaucoma Suspect, and Glaucoma Eyes

PubMed Central

Yarmohammadi, Adeleh; Zangwill, Linda M.; Diniz-Filho, Alberto; Suh, Min Hee; Manalastas, Patricia Isabel; Fatehee, Naeem; Yousefi, Siamak; Belghith, Akram; Saunders, Luke J.; Medeiros, Felipe A.; Huang, David; Weinreb, Robert N.

2016-01-01

Purpose The purpose of this study was to compare retinal nerve fiber layer (RNFL) thickness and optical coherence tomography angiography (OCT-A) retinal vasculature measurements in healthy, glaucoma suspect, and glaucoma patients. Methods Two hundred sixty-one eyes of 164 healthy, glaucoma suspect, and open-angle glaucoma (OAG) participants from the Diagnostic Innovations in Glaucoma Study with good quality OCT-A images were included. Retinal vasculature information was summarized as a vessel density map and as vessel density (%), which is the proportion of flowing vessel area over the total area evaluated. Two vessel density measurements extracted from the RNFL were analyzed: (1) circumpapillary vessel density (cpVD) measured in a 750-μm-wide elliptical annulus around the disc and (2) whole image vessel density (wiVD) measured over the entire image. Areas under the receiver operating characteristic curves (AUROC) were used to evaluate diagnostic accuracy. Results Age-adjusted mean vessel density was significantly lower in OAG eyes compared with glaucoma suspects and healthy eyes. (cpVD: 55.1 ± 7%, 60.3 ± 5%, and 64.2 ± 3%, respectively; P < 0.001; and wiVD: 46.2 ± 6%, 51.3 ± 5%, and 56.6 ± 3%, respectively; P < 0.001). For differentiating between glaucoma and healthy eyes, the age-adjusted AUROC was highest for wiVD (0.94), followed by RNFL thickness (0.92) and cpVD (0.83). The AUROCs for differentiating between healthy and glaucoma suspect eyes were highest for wiVD (0.70), followed by cpVD (0.65) and RNFL thickness (0.65). Conclusions Optical coherence tomography angiography vessel density had similar diagnostic accuracy to RNFL thickness measurements for differentiating between healthy and glaucoma eyes. These results suggest that OCT-A measurements reflect damage to tissues relevant to the pathophysiology of OAG. PMID:27409505

Color Doppler imaging of retinal diseases.

PubMed

Dimitrova, Galina; Kato, Satoshi

2010-01-01

Color Doppler imaging (CDI) is a widely used method for evaluating ocular circulation that has been used in a number of studies on retinal diseases. CDI assesses blood velocity parameters by using ultrasound waves. In ophthalmology, these assessments are mainly performed on the retrobulbar blood vessels: the ophthalmic, the central retinal, and the short posterior ciliary arteries. In this review, we discuss CDI use for the assessment of retinal diseases classified into the following: vascular diseases, degenerations, dystrophies, and detachment. The retinal vascular diseases that have been investigated by CDI include diabetic retinopathy, retinal vein occlusions, retinal artery occlusions, ocular ischemic conditions, and retinopathy of prematurity. Degenerations and dystrophies included in this review are age-related macular degeneration, myopia, and retinitis pigmentosa. CDI has been used for the differential diagnosis of retinal detachment, as well as the evaluation of retrobulbar circulation in this condition. CDI is valuable for research and is a potentially useful diagnostic tool in the clinical setting.

Insulin Sensitivity and Inflammation Mediate the Impact of Fitness on Cerebrovascular Health in Adolescents.

PubMed

Yau, Po Lai; Ross, Naima; Tirsi, Andrew; Arif, Arslan; Ozinci, Zeynep; Convit, Antonio

2017-06-01

To investigate in adolescents the relationships between retinal vessel diameter, physical fitness, insulin sensitivity, and systemic inflammation. We evaluated 157 adolescents, 112 with excessive weight and 45 lean, all without type 2 diabetes mellitus. All received detailed evaluations, including measurements of retinal vessel diameter, insulin sensitivity, levels of inflammation, and physical fitness. Overweight/obese adolescents had significantly narrower retinal arteriolar and wider venular diameters, significantly lower insulin sensitivity, and physical fitness. They also had decreased levels of anti-inflammatory and increased levels of proinflammatory markers as well as an overall higher inflammation balance score. Fitness was associated with larger retinal arteriolar and narrower venular diameters and these relationships were mediated by insulin sensitivity. We demonstrate that inflammation also mediates the relationship between fitness and retinal venular, but not arterial diameter; insulin sensitivity and inflammation balance score jointly mediate this relationship with little overlap in their effects. Increasing fitness and insulin sensitivity and reducing inflammation among adolescents carrying excess weight may improve microvascular integrity. Interventions to improve physical fitness and insulin function and reduce inflammation in adolescents, a group likely to benefit from such interventions, may reduce not only cardiovascular disease in middle age, but also improve cerebrovascular function later in life.

Optical Coherence Tomography Angiography of Retinal Microvascular Changes Overlying Choroidal Nodules in Neurofibromatosis Type 1

PubMed Central

Cassiman, Catherine; Casteels, Ingele; Stalmans, Peter; Legius, Eric; Jacob, Julie

2017-01-01

Purpose To report 3 cases of neurofibromatosis type 1 (NF1) with choroidal nodules associated with retinal microvascular changes imaged with optical coherence tomography angiography (OCTA). Methods Small case series in 3 NF1 patients. OCTA examinations were performed by a trained examiner (J.J.) after pupillary dilation. A standard scan, centered over the macula measuring 6 × 6 mm and 3 × 3 mm was obtained according to the findings on standard color photography. Additional scans were obtained in the zones with microvascular abnormalities. The segmentation provided by the machine software was used. Results Corkscrew retinal vessels were observed in association with “placoid”-type choroidal nodules as shown by near-infrared reflectance imaging. In all cases, multiple lesions were found. They were second- or third-order tortuous vessels originating from the superior or inferior temporal veins. OCTA demonstrated that the tortuous venules were located in the superficial capillary plexus, and no abnormalities were found in the deep capillary plexus. Discussion Corkscrew retinal vessels are part of a spectrum of retinal microvascular alterations seen in association, sometimes overlying choroidal nodules in patients with NF1 and are visualized in the superficial capillary plexus on OCTA. We demonstrated with OCTA that they are not associated with flow loss or ischemia in the superficial and deep capillary plexus. The link between the underlying nodule remains unclear. Since neovascularization was described in choroidal ganglioneuroma, we hypothesize that corresponding secretory substances from Schwann cells, ganglion cells, or melanocytes in choroidal nodules might alter the retinal vasculature. Conclusion We report on 3 cases of NF1 with choroidal nodules in association with retinal microvascular changes imaged with OCTA. OCTA demonstrated preservation of the blood flow in the deep and superficial capillary plexus of the retina. We hypothesize that angiogenic factors secreted by the underlying choroidal nodules could have an effect on the retinal vasculature. Further immunohistological studies in NF1 patients with choroidal nodules to detect angiogenic factors (such as VEGF) are necessary to confirm this hypothesis. PMID:28512424

Foveomacular schisis in juvenile X-linked retinoschisis: an optical coherence tomography study.

PubMed

Yu, Jia; Ni, Yingqin; Keane, Pearse A; Jiang, Chunhui; Wang, Wenji; Xu, Gezhi

2010-06-01

To explore the structural features of juvenile X-linked retinoschisis using spectral-domain optical coherence tomography (OCT). Retrospective, observational cross-sectional study. Eighteen male patients (34 eyes) who were diagnosed with juvenile X-linked retinoschisis at the Eye & ENT Hospital of Fudan University over an 18-month period were included. Their OCT images, which were obtained using spectral-domain OCT (Cirrus HD-OCT; Carl Zeiss Meditec), were analyzed. The anatomic location of the schisis cavity in juvenile X-linked retinoschisis was characterized by direct inspection of OCT images. On OCT, the schisis cavity was visible at the fovea in all 34 eyes, and it was associated with increased retinal thickness. Schisis was present at the retinal nerve fiber layer in 4 eyes, at the inner nuclear layer in 29 eyes, and at the outer nuclear layer/outer plexiform layer in 22 eyes. In most cases, widespread foveomacular schisis was detected using OCT; however, in 9 eyes (6 patients), the schisis was confined to the fovea. Schisis of the inner nuclear layer and outer nuclear layer/outer plexiform layer almost always involved the foveal center, but retinal nerve fiber layer schisis was seen only in the parafoveal area. Despite conventional wisdom, in patients with X-linked retinoschisis, the schisis cavity can occur in a number of different layers of the neurosensory retina (retinal nerve fiber layer, inner nuclear layer, and outer nuclear layer/outer plexiform layer). In addition, different forms of schisis may affect different locations in the macula (foveal vs parafoveal), and, in most eyes, the schisis involves the entire foveomacular region. Copyright 2010 Elsevier Inc. All rights reserved.

Mobile, Multi-modal, Label-Free Imaging Probe Analysis of Choroidal Oximetry and Retinal Hypoxia

DTIC Science & Technology

2015-10-01

eyes and image choroidal vessels/capillaries using CARS intravital microscopy Subtask 3: Measure oxy-hemoglobin levels in PBI test and control eyes...AWARD NUMBER: W81XWH-14-1-0537 TITLE: Mobile, Multi-modal, Label-Free Imaging Probe Analysis of Choroidal Oximetry and Retinal Hypoxia...4. TITLE AND SUBTITLE Mobile, Multimodal, Label-Free Imaging Probe Analysis of Choroidal Oximetry and Retinal Hypoxia 5a. CONTRACT NUMBER W81XWH

In vivo two-photon imaging of retina in rabbits and rats.

PubMed

Jayabalan, Gopal Swamy; Wu, Yi-Kai; Bille, Josef F; Kim, Samuel; Mao, Xiao Wen; Gimbel, Howard V; Rauser, Michael E; Fan, Joseph T

2018-01-01

The purpose of this study was to evaluate the retina using near-infrared (NIR) two-photon scanning laser ophthalmoscopy. New Zealand white rabbits, albino rats, and brown Norway rats were used in this study. An autofluorescence image of the retina, including the retinal cells and its associated vasculatures was obtained by a real-time scan using the ophthalmoscope. Furthermore, the retinal vessels, nerve fiber layers and the non-pigmented retina were recorded with two-photon fluorescein angiography (FA); and the choroidal vasculatures were recorded using two-photon indocyanine green angiography (ICGA). Two-photon ICGA was achieved by exciting a second singlet state at ∼398 nm. Simultaneous two-photon FA and two-photon ICGA were performed to characterize the retinal and choroidal vessels with a single injection. The minimum laser power threshold required to elicit two-photon fluorescence was determined. The two-photon ophthalmoscope could serve as a promising tool to detect and monitor the disease progression in animal models. Moreover, these high-resolution images of retinal and choroidal vessels can be acquired in a real-time scan with a single light source, requiring no additional filters for FA or ICGA. The combination of FA and ICGA using the two-photon ophthalmoscope will help researchers to characterize the retinal diseases in animal models, and also to classify the types (classic, occult or mixed) of choroidal neovascularization (CNV) in macular degeneration. Furthermore, the prototype can be adapted to image the retina of rodents and rabbits. Copyright © 2017 Elsevier Ltd. All rights reserved.

Retinal hemorrhage detection by rule-based and machine learning approach.

PubMed

Di Xiao; Shuang Yu; Vignarajan, Janardhan; Dong An; Mei-Ling Tay-Kearney; Kanagasingam, Yogi

2017-07-01

Robust detection of hemorrhages (HMs) in color fundus image is important in an automatic diabetic retinopathy grading system. Detection of the hemorrhages that are close to or connected with retinal blood vessels was found to be challenge. However, most methods didn't put research on it, even some of them mentioned this issue. In this paper, we proposed a novel hemorrhage detection method based on rule-based and machine learning methods. We focused on the improvement of detection of the hemorrhages that are close to or connected with retinal blood vessels, besides detecting the independent hemorrhage regions. A preliminary test for detecting HM presence was conducted on the images from two databases. We achieved sensitivity and specificity of 93.3% and 88% as well as 91.9% and 85.6% on the two datasets.

Ultrahigh-speed non-invasive widefield angiography

NASA Astrophysics Data System (ADS)

Blatter, Cedric; Klein, Thomas; Grajciar, Branislav; Schmoll, Tilman; Wieser, Wolfgang; Andre, Raphael; Huber, Robert; Leitgeb, Rainer A.

2012-07-01

Retinal and choroidal vascular imaging is an important diagnostic benefit for ocular diseases such as age-related macular degeneration. The current gold standard for vessel visualization is fluorescence angiography. We present a potential non-invasive alternative to image blood vessels based on functional Fourier domain optical coherence tomography (OCT). For OCT to compete with the field of view and resolution of angiography while maintaining motion artifacts to a minimum, ultrahigh-speed imaging has to be introduced. We employ Fourier domain mode locking swept source technology that offers high quality imaging at an A-scan rate of up to 1.68 MHz. We present retinal angiogram over ˜48 deg acquired in a few seconds in a single recording without the need of image stitching. OCT at 1060 nm allows for high penetration in the choroid and efficient separate characterization of the retinal and choroidal vascularization.

Axial length variation impacts on retinal vessel density and foveal avascular zone area measurement using optical coherence tomography angiography

NASA Astrophysics Data System (ADS)

Sampson, Danuta M.; Gong, Peijun; An, Di; Menghini, Moreno; Hansen, Alex; Mackey, David A.; Sampson, David D.; Chen, Fred K.

2017-04-01

We examined the impact of axial length on superficial retinal vessel density (SRVD) and foveal avascular zone area (FAZA) measurement using optical coherence tomography angiography. The SRVD and FAZA were quantified before and after correction for magnification error associated with axial length variation. Although SRVD did not differ before and after correction for magnification error in the parafoveal region, change in foveal SRVD and FAZA were significant. This has implications for clinical trials outcome in diseased eyes where significant capillary dropout may occur in the parafovea.

Nonrigid registration of 3D longitudinal optical coherence tomography volumes with choroidal neovascularization

NASA Astrophysics Data System (ADS)

Wei, Qiangding; Shi, Fei; Zhu, Weifang; Xiang, Dehui; Chen, Haoyu; Chen, Xinjian

2017-02-01

In this paper, we propose a 3D registration method for retinal optical coherence tomography (OCT) volumes. The proposed method consists of five main steps: First, a projection image of the 3D OCT scan is created. Second, the vessel enhancement filter is applied on the projection image to detect vessel shadow. Third, landmark points are extracted based on both vessel positions and layer information. Fourth, the coherent point drift method is used to align retinal OCT volumes. Finally, a nonrigid B-spline-based registration method is applied to find the optimal transform to match the data. We applied this registration method on 15 3D OCT scans of patients with Choroidal Neovascularization (CNV). The Dice coefficients (DSC) between layers are greatly improved after applying the nonrigid registration.

The Association of Type 2 Diabetes Mellitus with Cerebral Gray Matter Volume Is Independent of Retinal Vascular Architecture and Retinopathy.

PubMed

Moran, C; Tapp, R J; Hughes, A D; Magnussen, C G; Blizzard, L; Phan, T G; Beare, R; Witt, N; Venn, A; Münch, G; Amaratunge, B C; Srikanth, V

2016-01-01

It is uncertain whether small vessel disease underlies the relationship between Type 2 Diabetes Mellitus (T2DM) and brain atrophy. We aimed to study whether retinal vascular architecture, as a proxy for cerebral small vessel disease, may modify or mediate the associations of T2DM with brain volumes. In this cross-sectional study using Magnetic Resonance Imaging (MRI) scans and retinal photographs in 451 people with and without T2DM, we measured brain volumes, geometric measures of retinal vascular architecture, clinical retinopathy, and MRI cerebrovascular lesions. There were 270 people with (mean age 67.3 years) and 181 without T2DM (mean age 72.9 years). T2DM was associated with lower gray matter volume (p = 0.008). T2DM was associated with greater arteriolar diameter (p = 0.03) and optimality ratio (p = 0.04), but these associations were attenuated by adjustments for age and sex. Only optimality ratio was associated with lower gray matter volume (p = 0.03). The inclusion of retinal measures in regression models did not attenuate the association of T2DM with gray matter volume. The association of T2DM with lower gray matter volume was independent of retinal vascular architecture and clinical retinopathy. Retinal vascular measures or retinopathy may not be sufficiently sensitive to confirm a microvascular basis for T2DM-related brain atrophy.

The Planetarium and the Carl Zeiss Corporation, 1923-1933

NASA Astrophysics Data System (ADS)

Boyce-Jacino, Katherine

2018-01-01

The Carl Zeiss Company of Jena, Germany, introduced the first prototype planetarium in the fall of 1923. By 1933, there were a dozen planetaria in Germany alone, and nearly a dozen more abroad. This talk argues that on one hand, Zeiss saw the planetarium as an opportunity to reintroduce German engineering to a skeptical international market. On the other, Zeiss recognized that a large part of the planetarium’s domestic appeal lay in the romance of its German origins. Through an examination of Zeiss’ corporate correspondence, propaganda, and contemporary international and domestic press, this talk argues that in advertising the planetarium in Germany and abroad, the Zeiss company relied on competing constructions of a post-war German identity rooted in conflicting understandings of space.

Decompensation of a congenital retinal macrovessel with arteriovenous communications induced by repetitive rollercoaster rides.

PubMed

Beatty, S; Goodall, K; Radford, R; Lavin, M J

2000-10-01

To describe a congenital retinal venous macrovessel that communicates with a cilioretinal artery and a retinal artery, and to report how this vascular anomaly decompensated as a result of repetitive rollercoaster rides. Case report with serial fundus photography and fluorescein angiography. After a short period of intensive rollercoaster rides, a 19-year-old woman complained of reduced vision in one eye. Funduscopy and fluorescein angiography revealed a venous congenital retinal macrovessel with arteriovenous communications, and retinal exudation was visible at the termination of the anomalous vessel. Exudation resolved, and acuity recovered after a period of avoidance of rollercoaster rides. This case represents the first report of a retinal artery and a cilioretinal artery communicating with a congenital retinal macrovessel, and it suggests that such patients are at increased risk of retinal vascular decompensation if involved in activities associated with changes in g-forces, such as bungee jumping or rollercoaster rides.

Physiology of vitreous surgery.

PubMed

Stefánsson, Einar

2009-02-01

Vitreous surgery has various physiological and clinical consequences, both beneficial and harmful. Vitrectomy reduces the risk of retinal neovascularization, while increasing the risk of iris neovascularization, reduces macular edema and stimulates cataract formation. These clinical consequences may be understood with the help of classical laws of physics and physiology. The laws of Fick, Stokes-Einstein and Hagen-Poiseuille state that molecular transport by diffusion or convection is inversely related to the viscosity of the medium. When the vitreous gel is replaced with less viscous saline, the transport of all molecules, including oxygen and cytokines, is facilitated. Oxygen transport to ischemic retinal areas is improved, as is clearance of VEGF and other cytokines from these areas, thus reducing edema and neovascularization. At the same time, oxygen is transported faster down a concentration gradient from the anterior to the posterior segment, while VEGF moves in the opposite direction, making the anterior segment less oxygenated and with more VEGF, stimulating iris neovascularization. Silicone oil is the exception that proves the rule: it is more viscous than vitreous humour, re-establishes the transport barrier to oxygen and VEGF, and reduces the risk for iris neovascularization in the vitrectomized-lentectomized eye. Modern vitreous surgery involves a variety of treatment options in addition to vitrectomy itself, such as photocoagulation, anti-VEGF drugs, intravitreal steroids and release of vitreoretinal traction. A full understanding of these treatment modalities allows sensible combination of treatment options. Retinal photocoagulation has repeatedly been shown to improve retinal oxygenation, as does vitrectomy. Oxygen naturally reduces VEGF production and improves retinal hemodynamics. The VEGF-lowering effect of photocoagulation and vitrectomy can be augmented with anti-VEGF drugs and the permeability effect of VEGF reduced with corticosteroids. Starling's law explains vasogenic edema, which is controlled by osmotic and hydrostatic gradients between vessel and tissue. It explains the effect of VEGF-induced vascular permeability changes on plasma protein leakage and the osmotic gradient between vessel and tissue. At the same time, it takes into account hemodynamic changes that affect the hydrostatic gradient. This includes the influence of arterial blood pressure, and the effect oxygen (laser treatment) has in constricting retinal arterioles, increasing their resistance, and thus reducing the hydrostatic pressure in the microcirculation. Reduced capillary hydrostatic pressure and increased osmotic gradient reduce water fluxes from vessel to tissue and reduce edema. Finally, Newton's third law explains that vitreoretinal traction decreases hydrostatic tissue pressure in the retina, increases the pressure gradient between vessel and tissue, and stimulates water fluxes from vessel into tissue, leading to edema.

In vitro induction of protein complexes between bevacizumab, VEGF-A¹⁶⁵ and heparin: explanation for deposits observed on endothelial veins in monkey eyes.

PubMed

Julien, Sylvie; Biesemeier, Antje; Schraermeyer, Ulrich

2013-04-01

By investigating the effects of intravitreal bevacizumab on retinal vessels of monkeys, we found that bevacizumab accumulated locally at high concentration within individual blood vessels. It formed electron-dense fibrous deposits between endothelial cells and erythrocytes or granulocytes inducing retinal vein thrombosis. To better characterise the observed deposits, we investigated in vitro whether these deposits result from a complex between bevacizumab, vascular endothelial growth factor (VEGF)-A(165) and heparin. Cynomolgus monkeys were intravitreally injected with 1.25 mg bevacizumab. The eyes were enucleated between 1 and 14 days after injection and investigated by electron microscopy and immunohistochemistry. Human umbilical vein endothelial cells (HUVEC) were incubated with bevacizumab, VEGF-A(165) and heparin at different concentrations. Treatments with ranibizumab served as control. Bevacizumab and ranibizumab were detected immunohistochemically using Cy-3 or immunogold labelled antibodies. Treated animals showed bevacizumab locally at high concentration within retinal blood vessels. Electron-dense deposits inside retinal vessels and between erythrocytes were detected in three out of four treated monkeys. In vitro, many globular aggregates heavily stained with anti-human IgG were only observed with equimolar amounts (240 nM) of bevacizumab and VEGF-A(165) and 0.2 U/ml heparin and not after ranibizumab treatment. The immunogold labelling specifically localised ultrastructurally the complexes formed between bevacizumab, VEGF-A(165) and heparin at the surfaces of HUVEC cells. Heparin promotes bevacizumab immune complex deposition on to endothelial cells. Our in vitro results could explain the presence of deposits observed on endothelial veins in monkey eyes intravitreally injected with bevacizumab.

Computer-based detection of diabetes retinopathy stages using digital fundus images.

PubMed

Acharya, U R; Lim, C M; Ng, E Y K; Chee, C; Tamura, T

2009-07-01

Diabetes mellitus is a heterogeneous clinical syndrome characterized by hyperglycaemia and the long-term complications are retinopathy, neuropathy, nephropathy, and cardiomyopathy. It is a leading cause of blindness. Diabetic retinopathy is the progressive pathological alterations in the retinal microvasculature, leading to areas of retinal nonperfusion, increased vascular permeability, and the pathological proliferation of retinal vessels. Hence, it is beneficial to have regular cost-effective eye screening for diabetes subjects. Nowadays, different stages of diabetes retinopathy are detected by retinal examination using indirect biomicroscopy by senior ophthalmologists. In this work, morphological image processing and support vector machine (SVM) techniques were used for the automatic diagnosis of eye health. In this study, 331 fundus images were analysed. Five groups were identified: normal retina, mild non-proliferative diabetic retinopathy, moderate non-proliferative diabetic retinopathy, severe non-proliferative diabetic retinopathy, and proliferative diabetic retinopathy. Four salient features blood vessels, microaneurysms, exudates, and haemorrhages were extracted from the raw images using image-processing techniques and fed to the SVM for classification. A sensitivity of more than 82 per cent and specificity of 86 per cent was demonstrated for the system developed.

A novel method for segmentation of Infrared Scanning Laser Ophthalmoscope (IR-SLO) images of retina.

PubMed

Ajaz, Aqsa; Aliahmad, Behzad; Kumar, Dinesh K

2017-07-01

Retinal vessel segmentation forms an essential element of automatic retinal disease screening systems. The development of multimodal imaging system with IR-SLO and OCT could help in studying the early stages of retinal disease. The advantages of IR-SLO to examine the alterations in the structure of retina and direct correlation with OCT can be useful for assessment of various diseases. This paper presents an automatic method for segmentation of IR-SLO fundus images based on the combination of morphological filters and image enhancement techniques. As a first step, the retinal vessels are contrasted using morphological filters followed by background exclusion using Contrast Limited Adaptive Histogram Equalization (CLAHE) and Bilateral filtering. The final segmentation is obtained by using Isodata technique. Our approach was tested on a set of 26 IR-SLO images and results were compared to two set of gold standard images. The performance of the proposed method was evaluated in terms of sensitivity, specificity and accuracy. The system has an average accuracy of 0.90 for both the sets.

Blood vessel segmentation in color fundus images based on regional and Hessian features.

PubMed

Shah, Syed Ayaz Ali; Tang, Tong Boon; Faye, Ibrahima; Laude, Augustinus

2017-08-01

To propose a new algorithm of blood vessel segmentation based on regional and Hessian features for image analysis in retinal abnormality diagnosis. Firstly, color fundus images from the publicly available database DRIVE were converted from RGB to grayscale. To enhance the contrast of the dark objects (blood vessels) against the background, the dot product of the grayscale image with itself was generated. To rectify the variation in contrast, we used a 5 × 5 window filter on each pixel. Based on 5 regional features, 1 intensity feature and 2 Hessian features per scale using 9 scales, we extracted a total of 24 features. A linear minimum squared error (LMSE) classifier was trained to classify each pixel into a vessel or non-vessel pixel. The DRIVE dataset provided 20 training and 20 test color fundus images. The proposed algorithm achieves a sensitivity of 72.05% with 94.79% accuracy. Our proposed algorithm achieved higher accuracy (0.9206) at the peripapillary region, where the ocular manifestations in the microvasculature due to glaucoma, central retinal vein occlusion, etc. are most obvious. This supports the proposed algorithm as a strong candidate for automated vessel segmentation.

Research on the liquid crystal adaptive optics system for human retinal imaging

NASA Astrophysics Data System (ADS)

Zhang, Lei; Tong, Shoufeng; Song, Yansong; Zhao, Xin

2013-12-01

The blood vessels only in Human eye retinal can be observed directly. Many diseases that are not obvious in their early symptom can be diagnosed through observing the changes of distal micro blood vessel. In order to obtain the high resolution human retinal images,an adaptive optical system for correcting the aberration of the human eye was designed by using the Shack-Hartmann wavefront sensor and the Liquid Crystal Spatial Light Modulator(LCLSM) .For a subject eye with 8m-1 (8D)myopia, the wavefront error is reduced to 0.084 λ PV and 0.12 λRMS after adaptive optics(AO) correction ,which has reached diffraction limit.The results show that the LCLSM based AO system has the ability of correcting the aberration of the human eye efficiently,and making the blurred photoreceptor cell to clearly image on a CCD camera.

OCT Angiography Helps Distinguish Between Proliferative Macular Telangiectasia Type 2 and Neovascular Age-Related Macular Degeneration.

PubMed

Zheng, Fang; Motulsky, Elie H; de Oliveira Dias, João Rafael; de López, Edith Pérez; Gregori, Giovanni; Rosenfeld, Philip J

2018-05-01

To demonstrate the advantage of optical coherence tomography angiography (OCTA) for the diagnosis and management of proliferative macular telangiectasia type 2 (MacTel2) masquerading as neovascular age-related macular degeneration (AMD). This is an observational cases series. Three patients referred with the diagnosis of neovascular AMD were identified in this retrospective study. In addition to color fundus, fluorescein angiography, and spectral-domain OCT (SD-OCT) imaging, SD-OCTA (AngioPlex; Carl Zeiss Meditec, Dublin, CA) was performed. SD-OCTA revealed bilateral parafoveal retinal microvascular changes in three patients and unambiguously confirmed the diagnosis of MacTel2. OCTA is an important tool for the correct diagnosis of MacTel2 in older patients with the concomitant or masquerading diagnosis of AMD. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:303-312.]. Copyright 2018, SLACK Incorporated.

Reproducibility of Retinal Microvascular Traits Decoded by the Singapore I Vessel Assessment Software Across the Human Age Range.

PubMed

Huang, Qi-Fang; Wei, Fang-Fei; Zhang, Zhen-Yu; Raaijmakers, Anke; Asayama, Kei; Thijs, Lutgarde; Yang, Wen-Yi; Mujaj, Blerim; Allegaert, Karel; Verhamme, Peter; Struijker-Boudier, Harry A J; Li, Yan; Staessen, Jan A

2018-03-10

Retinal microvascular traits predict adverse health outcomes. The Singapore I Vessel Assessment (SIVA) software improved automated postprocessing of retinal photographs. In addition to microvessel caliber, it generates measures of arteriolar and venular geometry. Few studies addressed the reproducibility of SIVA measurements across a wide age range. In the current study, 2 blinded graders read images obtained by nonmydriatic retinal photography twice in 20 11-year-old children, born prematurely (n = 10) or at term (n = 10) and in 60 adults (age range, 18.9-86.1 years). Former preterm compared with term children had lower microvessel diameter and disorganized vessel geometry with no differences in intraobserver and interobserver variability. Among adults, microvessel caliber decreased with age and blood pressure and arteriolar geometry was inversely correlated with female sex and age. Intraobserver differences estimated by the Bland-Altman method did not reach significance for any measurement. Across measurements, median reproducibility (RM) expressed as percent of the average trait value was 8.8% in children (median intraclass correlation coefficient [ICC], 0.94) and 8.0% (0.97) in adults. Likewise, interobserver differences did not reach significance with RM (ICC) of 10.6% (0.85) in children and 10.4% (0.93) in adults. Reproducibility was best for microvessel caliber (intraobserver/interobserver RM, 4.7%/6.0%; ICC, 0.98/0.96), worst for venular geometry (17.0%/18.8%; 0.93/0.84), and intermediate for arteriolar geometry (10.9%/14.9%; 0.95/0.86). SIVA produces repeatable measures of the retinal microvasculature in former preterm and term children and in adults, thereby proving its usability from childhood to old age.

A boosted optimal linear learner for retinal vessel segmentation

NASA Astrophysics Data System (ADS)

Poletti, E.; Grisan, E.

2014-03-01

Ocular fundus images provide important information about retinal degeneration, which may be related to acute pathologies or to early signs of systemic diseases. An automatic and quantitative assessment of vessel morphological features, such as diameters and tortuosity, can improve clinical diagnosis and evaluation of retinopathy. At variance with available methods, we propose a data-driven approach, in which the system learns a set of optimal discriminative convolution kernels (linear learner). The set is progressively built based on an ADA-boost sample weighting scheme, providing seamless integration between linear learner estimation and classification. In order to capture the vessel appearance changes at different scales, the kernels are estimated on a pyramidal decomposition of the training samples. The set is employed as a rotating bank of matched filters, whose response is used by the boosted linear classifier to provide a classification of each image pixel into the two classes of interest (vessel/background). We tested the approach fundus images available from the DRIVE dataset. We show that the segmentation performance yields an accuracy of 0.94.

Automatic identification of vessel crossovers in retinal images

NASA Astrophysics Data System (ADS)

Sánchez, L.; Barreira, N.; Penedo, M. G.; Cancela, B.

2015-02-01

Crossovers and bifurcations are interest points of the retinal vascular tree useful to diagnose diseases. Specifically, detecting these interest points and identifying which of them are crossings will give us the opportunity to search for arteriovenous nicking, this is, an alteration of the vessel tree where an artery is crossed by a vein and the former compresses the later. These formations are a clear indicative of hypertension, among other medical problems. There are several studies that have attempted to define an accurate and reliable method to detect and classify these relevant points. In this article, we propose a new method to identify crossovers. Our approach is based on segmenting the vascular tree and analyzing the surrounding area of each interest point. The minimal path between vessel points in this area is computed in order to identify the connected vessel segments and, as a result, to distinguish between bifurcations and crossovers. Our method was tested using retinographies from public databases DRIVE and VICAVR, obtaining an accuracy of 90%.

Flicker-induced retinal vasodilatation is not dependent on complement factor H polymorphism in healthy young subjects.

PubMed

Told, Reinhard; Palkovits, Stefan; Boltz, Agnes; Schmidl, Doreen; Napora, Katarzyna J; Werkmeister, René M; Haslacher, Helmuth; Frantal, Sophie; Popa-Cherecheanu, Alina; Schmetterer, Leopold; Garhöfer, Gerhard

2014-11-01

The complement factor H (CFH) tyrosine 402 histidine (Y402H, rs1061170) variant is known to be significantly associated with age-related macular degeneration (AMD). Whether this genetic variant may impact retinal blood flow regulation is largely unknown. This study investigated whether flicker-induced vasodilation, an indicator for the coupling between neural activity and blood flow, is altered in subjects carrying the rs1061170 risk allele. One hundred healthy subjects (aged between 18 and 45 years) were included in this study. Retinal blood flow regulation was tested by assessing retinal vessel calibres in response to stimulation with diffuse flicker light. Retinal vascular flicker responses were determined with a Dynamic Vessel Analyzer (DVA). In addition, genotyping for rs1061170 was performed. Eighteen subjects were homozygous for the risk allele C, 50 were homozygous for the ancestral allele T, and 31 subjects were heterozygous (CT). One subject had to be excluded from data evaluation, as no genetic analysis could be performed due to technical difficulties. Baseline diameters of retinal arteries (p = 0.39) and veins (p = 0.64) were comparable between the three groups. Flicker-induced vasodilation in both retinal arteries (p = 0.38) and retinal veins (p = 0.62) was also comparable between the three studied groups. Our data indicate that homozygous healthy young carriers of the C risk allele at rs1061170 do not show abnormal flicker-induced vasodilation in the retina. This suggests that the high-risk genetic variant of CFH polymorphism does not impact neuro-vascular coupling in healthy subjects. © 2014 The Authors. Acta Ophthalmologica published by John Wiley & Sons Ltd on behalf of Acta Ophthalmologica Scandinavica Foundation.

Novel Genetic Loci Associated with Retinal Microvascular Diameter

PubMed Central

Jensen, Richard A.; Sim, Xueling; Smith, Albert Vernon; Li, Xiaohui; Jakobsdóttir, Jóhanna; Cheng, Ching-Yu; Brody, Jennifer A.; Cotch, Mary Frances; Mcknight, Barbara; Klein, Ronald; Wang, Jie Jin; Kifley, Annette; Harris, Tamara B.; Launer, Lenore J.; Taylor, Kent D.; Klein, Barbara E.K.; Raffel, Leslie J.; Li, Xiang; Ikram, M. Arfan; Klaver, Caroline C.; van der Lee, Sven J.; Mutlu, Unal; Hofman, Albert; Uitterlinden, Andre G.; Liu, Chunyu; Kraja, Aldi T.; Mitchell, Paul; Gudnason, Vilmundur; Rotter, Jerome I.; Boerwinkle, Eric; van Duijn, Cornelia M.; Psaty, Bruce M.; Wong, Tien Y.

2015-01-01

Background There is increasing evidence that retinal microvascular diameters are associated with cardio- and cerebrovascular conditions. The shared genetic effects of these associations are currently unknown. The aim of this study was to increase our understanding of the genetic factors that mediate retinal vessel size. Methods and Results This study extends previous genome-wide association study results using 24,000+ multi-ethnic participants from 7 discovery and 5,000+ subjects of European ancestry from 2 replication cohorts. Using the Illumina HumanExome BeadChip, we investigate the association of single nucleotide polymorphisms (SNPs) and variants collectively across genes with summary measures of retinal vessel diameters, referred to as the central retinal venule equivalent (CRVE) and the central retinal arteriole equivalent (CRAE). We report 4 new loci associated with CRVE, one of which is also associated with CRAE. The 4 SNPs are rs7926971 in TEAD1 (p=3.1×10−11, minor allele frequency (MAF)=0.43), rs201259422 in TSPAN10 (p=4.4×10−9, MAF=0.27), rs5442 in GNB3 (p=7.0×10−10, MAF=0.05) and rs1800407 in OCA2 (p=3.4×10−8, MAF=0.05). The latter SNP, rs1800407, was also associated with CRAE (p=6.5×10−12). Results from the gene-based burden tests were null. In phenotype look-ups, SNP rs201255422 was associated with both systolic (p=0.001) and diastolic blood pressure (p=8.3×10−04). Conclusions Our study expands the understanding of genetic factors influencing the size of the retinal microvasculature. These findings may also provide insight into the relationship between retinal and systemic microvascular disease. PMID:26567291

Short-term treatment with VEGF receptor inhibitors induces retinopathy of prematurity-like abnormal vascular growth in neonatal rats.

PubMed

Nakano, Ayuki; Nakahara, Tsutomu; Mori, Asami; Ushikubo, Hiroko; Sakamoto, Kenji; Ishii, Kunio

2016-02-01

Retinal arterial tortuosity and venous dilation are hallmarks of plus disease, which is a severe form of retinopathy of prematurity (ROP). In this study, we examined whether short-term interruption of vascular endothelial growth factor (VEGF) signals leads to the formation of severe ROP-like abnormal retinal blood vessels. Neonatal rats were treated subcutaneously with the VEGF receptor (VEGFR) tyrosine kinase inhibitors, KRN633 (1, 5, or 10 mg/kg) or axitinib (10 mg/kg), on postnatal day (P) 7 and P8. The retinal vasculatures were examined on P9, P14, or P21 in retinal whole-mounts stained with an endothelial cell marker. Prevention of vascular growth and regression of some preformed capillaries were observed on P9 in retinas of rats treated with KRN633. However, on P14 and P21, density of capillaries, tortuosity index of arterioles, and diameter of veins significantly increased in KRN633-treated rats, compared to vehicle (0.5% methylcellulose)-treated animals. Similar observations were made with axitinib-treated rats. Expressions of VEGF and VEGFR-2 were enhanced on P14 in KRN633-treated rat retinas. The second round of KRN633 treatment on P11 and P12 completely blocked abnormal retinal vascular growth on P14, but thereafter induced ROP-like abnormal retinal blood vessels by P21. These results suggest that an interruption of normal retinal vascular development in neonatal rats as a result of short-term VEGFR inhibition causes severe ROP-like abnormal retinal vascular growth in a VEGF-dependent manner. Rats treated postnatally with VEGFR inhibitors could serve as an animal model for studying the mechanisms underlying the development of plus disease. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fatty Acid Binding Protein 4 Deficiency Protects against Oxygen-Induced Retinopathy in Mice

PubMed Central

Saint-Geniez, Magali; Ghelfi, Elisa; Liang, Xiaoliang; Yu, Chenwei; Spencer, Carrie; Abend, Stephanie; Hotamisligil, Gokhan; Cataltepe, Sule

2014-01-01

Retinopathy of prematurity (ROP) is a leading cause of blindness in children worldwide due to increasing survival rates of premature infants. Initial suppression, followed by increased production of the retinal vascular endothelial growth factor-A (VEGF) expression are key events that trigger the pathological neovascularization in ROP. Fatty acid binding protein 4 (FABP4) is an intracellular lipid chaperone that is induced by VEGF in a subset of endothelial cells. FABP4 exhibits a pro-angiogenic function in cultured endothelial cells and in airway microvasculature, but whether it plays a role in modulation of retinal angiogenesis is not known. We hypothesized that FABP4 deficiency could ameliorate pathological retinal vascularization and investigated this hypothesis using a well-characterized mouse model of oxygen-induced retinopathy (OIR). We found that FABP4 was not expressed in retinal vessels, but was present in resident macrophages/microglial cells and endothelial cells of the hyaloid vasculature in the immature retina. While FABP4 expression was not required for normal development of retinal vessels, FABP4 expression was upregulated and localized to neovascular tufts in OIR. FABP4−/− mice demonstrated a significant decrease in neovessel formation as well as a significant improvement in physiological revascularization of the avascular retinal tissues. These alterations in retinal vasculature were accompanied by reduced endothelial cell proliferation, but no effect on apoptosis or macrophage/microglia recruitment. FABP4−/− OIR samples demonstrated decreased expression of genes involved in angiogenesis, such as Placental Growth Factor, and angiopoietin 2. Collectively, our findings suggest FABP4 as a potential target of pathologic retinal angiogenesis in proliferative retinopathies. PMID:24802082

Automated Detection of Malarial Retinopathy in Digital Fundus Images for Improved Diagnosis in Malawian Children with Clinically Defined Cerebral Malaria.

PubMed

Joshi, Vinayak; Agurto, Carla; Barriga, Simon; Nemeth, Sheila; Soliz, Peter; MacCormick, Ian J; Lewallen, Susan; Taylor, Terrie E; Harding, Simon P

2017-02-15

Cerebral malaria (CM), a complication of malaria infection, is the cause of the majority of malaria-associated deaths in African children. The standard clinical case definition for CM misclassifies ~25% of patients, but when malarial retinopathy (MR) is added to the clinical case definition, the specificity improves from 61% to 95%. Ocular fundoscopy requires expensive equipment and technical expertise not often available in malaria endemic settings, so we developed an automated software system to analyze retinal color images for MR lesions: retinal whitening, vessel discoloration, and white-centered hemorrhages. The individual lesion detection algorithms were combined using a partial least square classifier to determine the presence or absence of MR. We used a retrospective retinal image dataset of 86 pediatric patients with clinically defined CM (70 with MR and 16 without) to evaluate the algorithm performance. Our goal was to reduce the false positive rate of CM diagnosis, and so the algorithms were tuned at high specificity. This yielded sensitivity/specificity of 95%/100% for the detection of MR overall, and 65%/94% for retinal whitening, 62%/100% for vessel discoloration, and 73%/96% for hemorrhages. This automated system for detecting MR using retinal color images has the potential to improve the accuracy of CM diagnosis.

Automated Detection of Malarial Retinopathy in Digital Fundus Images for Improved Diagnosis in Malawian Children with Clinically Defined Cerebral Malaria

NASA Astrophysics Data System (ADS)

Joshi, Vinayak; Agurto, Carla; Barriga, Simon; Nemeth, Sheila; Soliz, Peter; MacCormick, Ian J.; Lewallen, Susan; Taylor, Terrie E.; Harding, Simon P.

2017-02-01

Cerebral malaria (CM), a complication of malaria infection, is the cause of the majority of malaria-associated deaths in African children. The standard clinical case definition for CM misclassifies ~25% of patients, but when malarial retinopathy (MR) is added to the clinical case definition, the specificity improves from 61% to 95%. Ocular fundoscopy requires expensive equipment and technical expertise not often available in malaria endemic settings, so we developed an automated software system to analyze retinal color images for MR lesions: retinal whitening, vessel discoloration, and white-centered hemorrhages. The individual lesion detection algorithms were combined using a partial least square classifier to determine the presence or absence of MR. We used a retrospective retinal image dataset of 86 pediatric patients with clinically defined CM (70 with MR and 16 without) to evaluate the algorithm performance. Our goal was to reduce the false positive rate of CM diagnosis, and so the algorithms were tuned at high specificity. This yielded sensitivity/specificity of 95%/100% for the detection of MR overall, and 65%/94% for retinal whitening, 62%/100% for vessel discoloration, and 73%/96% for hemorrhages. This automated system for detecting MR using retinal color images has the potential to improve the accuracy of CM diagnosis.

[Retinopathy of prematurity].

PubMed

Promelle, V; Milazzo, S

2017-05-01

Retinopathy of prematurity is a retinal vasoproliferative disease affecting extremely preterm infants exposed to high concentrations of oxygen therapy. Infants born before 32 post-menstrual weeks or with a birth weight of less than 1500g should systematically have a dilated fundus examination. The time of screening and schedule for follow-up are guided by the various risk factors. This disease results from immaturity of the peripheral retinal vessels at the time of premature birth. The classification of ROP depends on the anteroposterior extent of involvement (from center to periphery: zone I, II and III), its extension in 30° sectors (clock hours) and its stage (stage 1 to 5). "Plus" disease is defined as dilation and tortuosity of the retinal blood vessels in the posterior pole of the eye and represents a major risk factor for rapid unfavorable progression. A majority of patients will spontaneously recover, but patients with a high risk of progression will require treatment to prevent retinal detachment and blindness. The indications for treatment are threshold disease and type 1 pre-threshold disease. The current treatment of choice is peripheral retinal ablation with transpupillary laser, but ab externo cryotherapy may be used instead. Intravitreal injection of vascular endothelial growth factor inhibitors may be an attractive therapeutic option and is currently under investigation. After laser treatment, unfavorable outcomes occur in only 9 to 14 % of eyes, but at the price of peripheral retinal destruction. For all patients, whether treated or not, a regular fundus examination should be insured until complete retinal vascularization has occurred. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Vessel segmentation in 3D spectral OCT scans of the retina

NASA Astrophysics Data System (ADS)

Niemeijer, Meindert; Garvin, Mona K.; van Ginneken, Bram; Sonka, Milan; Abràmoff, Michael D.

2008-03-01

The latest generation of spectral optical coherence tomography (OCT) scanners is able to image 3D cross-sectional volumes of the retina at a high resolution and high speed. These scans offer a detailed view of the structure of the retina. Automated segmentation of the vessels in these volumes may lead to more objective diagnosis of retinal vascular disease including hypertensive retinopathy, retinopathy of prematurity. Additionally, vessel segmentation can allow color fundus images to be registered to these 3D volumes, possibly leading to a better understanding of the structure and localization of retinal structures and lesions. In this paper we present a method for automatically segmenting the vessels in a 3D OCT volume. First, the retina is automatically segmented into multiple layers, using simultaneous segmentation of their boundary surfaces in 3D. Next, a 2D projection of the vessels is produced by only using information from certain segmented layers. Finally, a supervised, pixel classification based vessel segmentation approach is applied to the projection image. We compared the influence of two methods for the projection on the performance of the vessel segmentation on 10 optic nerve head centered 3D OCT scans. The method was trained on 5 independent scans. Using ROC analysis, our proposed vessel segmentation system obtains an area under the curve of 0.970 when compared with the segmentation of a human observer.

Automated intraretinal segmentation of SD-OCT images in normal and age-related macular degeneration eyes

PubMed Central

de Sisternes, Luis; Jonna, Gowtham; Moss, Jason; Marmor, Michael F.; Leng, Theodore; Rubin, Daniel L.

2017-01-01

This work introduces and evaluates an automated intra-retinal segmentation method for spectral-domain optical coherence (SD-OCT) retinal images. While quantitative assessment of retinal features in SD-OCT data is important, manual segmentation is extremely time-consuming and subjective. We address challenges that have hindered prior automated methods, including poor performance with diseased retinas relative to healthy retinas, and data smoothing that obscures image features such as small retinal drusen. Our novel segmentation approach is based on the iterative adaptation of a weighted median process, wherein a three-dimensional weighting function is defined according to image intensity and gradient properties, and a set of smoothness constraints and pre-defined rules are considered. We compared the segmentation results for 9 segmented outlines associated with intra-retinal boundaries to those drawn by hand by two retinal specialists and to those produced by an independent state-of-the-art automated software tool in a set of 42 clinical images (from 14 patients). These images were obtained with a Zeiss Cirrus SD-OCT system, including healthy, early or intermediate AMD, and advanced AMD eyes. As a qualitative evaluation of accuracy, a highly experienced third independent reader blindly rated the quality of the outlines produced by each method. The accuracy and image detail of our method was superior in healthy and early or intermediate AMD eyes (98.15% and 97.78% of results not needing substantial editing) to the automated method we compared against. While the performance was not as good in advanced AMD (68.89%), it was still better than the manual outlines or the comparison method (which failed in such cases). We also tested our method’s performance on images acquired with a different SD-OCT manufacturer, collected from a large publicly available data set (114 healthy and 255 AMD eyes), and compared the data quantitatively to reference standard markings of the internal limiting membrane and inner boundary of retinal pigment epithelium, producing a mean unsigned positioning error of 6.04 ± 7.83µm (mean under 2 pixels). Our automated method should be applicable to data from different OCT manufacturers and offers detailed layer segmentations in healthy and AMD eyes. PMID:28663874

Reproducibility of the retinal vascular response to flicker light in Asians.

PubMed

Nguyen, Thanh T; Kreis, Andreas J; Kawasaki, Ryo; Wang, Jie Jin; Seifert, Bernd-U; Vilser, Walthard; Nagel, Edgar; Wong, Tien Y

2009-12-01

Dilation of retinal vessels in response to diffuse luminance flicker may reflect endothelial function. Although this has previously been shown to be reproducible in whites, there have been no similar data in Asians. We assess the reproducibility of repeated measurements of this response in Asians. Healthy Asians (n = 33) with normal vision and no history of glaucoma, age-related macular degeneration, cataract, or retinal arterial/venous occlusion participated in this study. Repeated measures from the same subjects were taken 30-60 min apart using the Dynamic Vessel Analyser (DVA, IMEDOS, Jena, Germany). Modification was made to the shape of the light source for Asian participants. Correlations of the first and second measures were assessed using Pearson correlation (R(2)), and agreement between the two measures was shown using Bland-Altman plots. After modification to the shape of the light source, almost perfect correlation was found between the 1st and 2nd measurements of baseline arteriolar (R(2) = 0.95) and venular diameters (R(2) = 0.98) of arteriolar maximum dilation (R(2) = 0.85). Substantially high correlation between the 1st and 2nd measurements of venular maximum dilation was found (R(2) = 0.80). Measurements of the dilation response of retinal vessels to diffuse luminance flicker an Asian sample using the DVA show high reproducibility for repeated measures over a short period of time. Such measurements may allow non-invasive quantification of endothelial function to study its association with systemic and ocular diseases.

A comparative study on preprocessing techniques in diabetic retinopathy retinal images: illumination correction and contrast enhancement.

PubMed

Rasta, Seyed Hossein; Partovi, Mahsa Eisazadeh; Seyedarabi, Hadi; Javadzadeh, Alireza

2015-01-01

To investigate the effect of preprocessing techniques including contrast enhancement and illumination correction on retinal image quality, a comparative study was carried out. We studied and implemented a few illumination correction and contrast enhancement techniques on color retinal images to find out the best technique for optimum image enhancement. To compare and choose the best illumination correction technique we analyzed the corrected red and green components of color retinal images statistically and visually. The two contrast enhancement techniques were analyzed using a vessel segmentation algorithm by calculating the sensitivity and specificity. The statistical evaluation of the illumination correction techniques were carried out by calculating the coefficients of variation. The dividing method using the median filter to estimate background illumination showed the lowest Coefficients of variations in the red component. The quotient and homomorphic filtering methods after the dividing method presented good results based on their low Coefficients of variations. The contrast limited adaptive histogram equalization increased the sensitivity of the vessel segmentation algorithm up to 5% in the same amount of accuracy. The contrast limited adaptive histogram equalization technique has a higher sensitivity than the polynomial transformation operator as a contrast enhancement technique for vessel segmentation. Three techniques including the dividing method using the median filter to estimate background, quotient based and homomorphic filtering were found as the effective illumination correction techniques based on a statistical evaluation. Applying the local contrast enhancement technique, such as CLAHE, for fundus images presented good potentials in enhancing the vasculature segmentation.

Retinopathy of prematurity: An update on screening and management

PubMed Central

Jefferies, Ann L

2016-01-01

Retinopathy of prematurity is a proliferative disorder of the developing retinal blood vessels in preterm infants. The present practice point reviews new information regarding screening and management for retinopathy of prematurity, including the role of risk factors in screening, optimal scheduling for screening examinations, pain management, digital retinal photography and antivascular endothelial growth factor therapy. PMID:27095887

Clinicopathologic correlation of argon laser photocoagulation of retinal angiomas in a patient with von Hippel-Lindau disease followed for more than 20 years.

PubMed

Rosa, R H; Goldberg, M F; Green, W R

1996-01-01

The authors review the histopathologic findings in the eyes of a patient with multiple retinal angiomas and von Hippel-Lindau disease, who underwent treatment with argon laser photocoagulation with follow-up of more than 20 years. The patient was studied ophthalmoscopically and by fluorescein angiography before and after argon laser photocoagulation of retinal angiomas. The eyes were obtained postmortem, and the central portion of the right eye, including the macula and optic nerve head, was sectioned serially for light microscopy. The pupil-optic nerve segment of the left eye was step-sectioned serially for light microscopy. Histopathologic study of the right eye disclosed mild cystoid macular edema and focal areas of exudation in the midperiphery possibly secondary to irradiation of the head. A 1.5 x 0.3-mm area of residual angioma was present in the nasal peripapillary retina. Superotemporally, four chorioretinal scars were present in one photocoagulated area. These scars were composed of dense fibrous tissue with vascularization and variable retinal pigment epithelium hyperplasia. Large, nonangiomatous vessels within each of the scars were continuous with other retinal vessels. Inferotemporally, two chorioretinal scars were present in one photocoagulated area. Histopathologically, these scars were similar to the superotemporal scars, except that no patent retinal vessels traversed the inferotemporal scars. Neovascularization of the retina was associated with one superotemporal and one inferotemporal scar. No residual angiomatous tissue was present in the supero- or inferotemporal areas. Histopathologic examination of the left eye disclosed extensive vitreous organization and periretinal fibrovascular proliferation, extensive gliosis of the retina, and a 4.5 x 2-mm schisis cavity filled with fibrinous exudate. Three angiomas with variable fibrosis were present in the left eye. Despite a poor clinical course in one eye treated with xenon arc photocoagulation, trans-scleral diathermy, and argon laser photocoagulation, a patient with von Hippel-Lindau disease and multiple retinal angiomas retained good vision in the other eye after successful treatment with argon laser photocoagulation with follow-up of more than 20 years. The amount of regression of angiomatous tissue after photocoagulation varied from lesion to lesion (complete in some; minimal in others). The authors conclude that argon laser photocoagulation of early lesions is effective in ablating smaller ( < or = 3-disc diameter) retinal angiomas.

Hypoxia-induced retinal neovascularization in zebrafish embryos: a potential model of retinopathy of prematurity.

PubMed

Wu, Yu-Ching; Chang, Chao-Yuan; Kao, Alex; Hsi, Brian; Lee, Shwu-Huey; Chen, Yau-Hung; Wang, I-Jong

2015-01-01

Retinopathy of prematurity, formerly known as a retrolental fibroplasia, is a leading cause of infantile blindness worldwide. Retinopathy of prematurity is caused by the failure of central retinal vessels to reach the retinal periphery, creating a nonperfused peripheral retina, resulting in retinal hypoxia, neovascularization, vitreous hemorrhage, vitreoretinal fibrosis, and loss of vision. We established a potential retinopathy of prematurity model by using a green fluorescent vascular endothelium zebrafish transgenic line treated with cobalt chloride (a hypoxia-inducing agent), followed by GS4012 (a vascular endothelial growth factor inducer) at 24 hours postfertilization, and observed that the number of vascular branches and sprouts significantly increased in the central retinal vascular trunks 2-4 days after treatment. We created an angiography method by using tetramethylrhodamine dextran, which exhibited severe vascular leakage through the vessel wall into the surrounding retinal tissues. The quantification of mRNA extracted from the heads of the larvae by using real-time quantitative polymerase chain reaction revealed a twofold increase in vegfaa and vegfr2 expression compared with the control group, indicating increased vascular endothelial growth factor signaling in the hypoxic condition. In addition, we demonstrated that the hypoxic insult could be effectively rescued by several antivascular endothelial growth factor agents such as SU5416, bevacizumab, and ranibizumab. In conclusion, we provide a simple, highly reproducible, and clinically relevant retinopathy of prematurity model based on zebrafish embryos; this model may serve as a useful platform for clarifying the mechanisms of human retinopathy of prematurity and its progression.

Novel cellular bouton structure activated by ATP in the vascular wall of porcine retinal arterioles.

PubMed

Misfeldt, Mikkel Wölck; Aalkjaer, Christian; Simonsen, Ulf; Bek, Toke

2010-12-01

The retinal blood flow is regulated by the tone of resistance arterioles, which is influenced by purinergic compounds such as adenosine and adenosine 5'-triphosphate (ATP) released from the retinal tissue. However, it is unknown what cellular elements in the perivascular retina are responsible for the effect of purines on the tone of retinal arterioles. Porcine retinal arterioles were loaded with the calcium-sensitive fluorophore Oregon green. The vessels were mounted in a confocal myograph for simultaneous recordings of tone and calcium activity in cells of the vascular wall during stimulation with ATP and adenosine, with and without modifiers of these compounds. Additionally, immunohistochemistry was used to localize elements with calcium activity in the vascular wall. Hyperfluorescence indicating calcium activity was recorded in a population of abundant round boutons interspersed in a network of vimentin-positive processes located immediately external to the smooth muscle cell layer but internal to the perivascular glial cells. These structures showed calcium activity when the vessel was relaxed with ATP but not when it was relaxed with adenosine. Ryanodine reduced calcium activity in the boutons, whereas the ATP antagonist adenosine-5'-O-(α, β- methylene diphosphate) reduced calcium activity in both the boutons and vascular tone. The vasodilating effect of purines in porcine retinal tissue involves ATP-dependent calcium activity in a layer of cellular boutons located external to the vascular smooth muscle cells and internal to the perivascular glial cells.

SPOTTED FEVER GROUP RICKETTSIA RETINITIS IN A TRAVELER TO AFRICA.

PubMed

Duval, Renaud; Merrill, Pauline T

2016-01-01

To describe a case of rickettsial retinitis in a traveler returning from Africa. Case description. A 67-year-old woman returning from an excursion in the jungles of Africa presented with a 2-day history of floaters and decreased vision in the right eye. In the two preceding weeks, she had experienced fever, malaise, a black eschar on the right elbow, and a rash on her extremities. Examination revealed panuveitis with a solitary, white retinal lesion adjacent to a retinal vessel in the posterior pole of each eye. Extensive diagnostic workup revealed a positive serology for rickettsial antibodies. Her treatment consisted of a course of oral doxycycline. Rickettsial retinitis is an emerging ocular infection in several endemic areas. This case description constitutes the first report of spotted fever group rickettsial retinitis in a traveler to Africa.

Snapshot hyperspectral retinal imaging using compact spectral resolving detector array.

PubMed

Li, Hao; Liu, Wenzhong; Dong, Biqin; Kaluzny, Joel V; Fawzi, Amani A; Zhang, Hao F

2017-06-01

Hyperspectral retinal imaging captures the light spectrum from each imaging pixel. It provides spectrally encoded retinal physiological and morphological information, which could potentially benefit diagnosis and therapeutic monitoring of retinal diseases. The key challenges in hyperspectral retinal imaging are how to achieve snapshot imaging to avoid motions between the images from multiple spectral bands, and how to design a compact snapshot imager suitable for clinical use. Here, we developed a compact, snapshot hyperspectral fundus camera for rodents using a novel spectral resolving detector array (SRDA), on which a thin-film Fabry-Perot cavity filter was monolithically fabricated on each imaging pixel. We achieved hyperspectral retinal imaging with 16 wavelength bands (460 to 630 nm) at 20 fps. We also demonstrated false-color vessel contrast enhancement and retinal oxygen saturation (sO 2 ) measurement through spectral analysis. This work could potentially bring hyperspectral retinal imaging from bench to bedside. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis by NASA's VESGEN Software of Retinal Blood Vessels in Human Subjects Undergoing Head-Down Tilt During 70-Day Bed Rest

NASA Technical Reports Server (NTRS)

Vyas, Ruchi J.; Murray, Matthew C.; Predovic, Marina; Lim, Shiyin; Askin, Kayleigh N.; Vizzeri, Gianmarco; Taibbi, Giovanni; Mason, Sara Stroble; Zanello, Susana B.; Young, Millenia;

Influence of cataract surgery on optical coherence tomography and neurophysiology measurements in patients with retinitis pigmentosa.

PubMed

Garcia-Martin, Elena; Rodriguez-Mena, Diego; Dolz, Isabel; Almarcegui, Carmen; Gil-Arribas, Laura; Bambo, Maria P; Larrosa, Jose M; Polo, Vicente; Pablo, Luis E

2013-08-01

To evaluate the effect of uncomplicated cataract phacoemulsification on the measurements of visual evoked potentials (VEP), pattern electroretinogram (PERG), and macular and retinal nerve fiber layer (RNFL) using 2 spectral-domain optical coherence tomography (OCT) instruments, the Cirrus OCT (Carl Zeiss Meditech) and Spectralis OCT (Heidelberg Engineering), in patients with retinitis pigmentosa (RP), and to assess the reliability of the OCT measurements before and after cataract surgery. Observational cross-sectional study. Thirty-five eyes of 35 patients with RP (20 men and 15 women, 45-66 years) who underwent cataract phacoemulsification were studied. At 1 month before and 1 month after surgery, visual acuity, VEP, PERG, and 3 repetitions of scans using the RNFL and macular analysis protocols of the Cirrus and Spectralis OCT instruments were performed. The differences in measurements between the 2 visits were analyzed. Repeatability of OCT measurements was evaluated by calculating the coefficients of variation. VEP amplitude, RNFL thicknesses provided by Cirrus and Spectralis, and macular measurements provided by Cirrus OCT differed between the 2 visits. VEP latency, PERG measurements, and macular thicknesses provided by the Spectralis OCT before surgery did not differ significantly from those after surgery. The OCT repeatability was better after surgery, with lower coefficients of variation for scans performed after surgical removal of the cataract. The nuclear, cortical, and posterior subcapsular types of cataracts did not show different repeatability. The presence of cataracts affects VEP amplitude, RNFL, and macular measurements performed with OCT in eyes with RP. Image repeatability significantly improves after cataract phacoemulsification. Copyright © 2013 Elsevier Inc. All rights reserved.

Multispectral fundus imaging for early detection of diabetic retinopathy

NASA Astrophysics Data System (ADS)

Beach, James M.; Tiedeman, James S.; Hopkins, Mark F.; Sabharwal, Yashvinder S.

1999-04-01

Functional imaging of the retina and associated structures may provide information for early assessment of risks of developing retinopathy in diabetic patients. Here we show results of retinal oximetry performed using multi-spectral reflectance imaging techniques to assess hemoglobin (Hb) oxygen saturation (OS) in blood vessels of the inner retina and oxygen utilization at the optic nerve in diabetic patients without retinopathy and early disease during experimental hyperglycemia. Retinal images were obtained through a fundus camera and simultaneously recorded at up to four wavelengths using image-splitting modules coupled to a digital camera. Changes in OS in large retinal vessels, in average OS in disk tissue, and in the reduced state of cytochrome oxidase (CO) at the disk were determined from changes in reflectance associated with the oxidation/reduction states of Hb and CO. Step to high sugar lowered venous oxygen saturation to a degree dependent on disease duration. Moderate increase in sugar produced higher levels of reduced CO in both the disk and surrounding tissue without a detectable change in average tissue OS. Results suggest that regulation of retinal blood supply and oxygen consumption are altered by hyperglycemia and that such functional changes are present before clinical signs of retinopathy.

Comparison between optical coherence tomography angiography and fluorescein angiography findings in retinal vasculitis.

PubMed

Abucham-Neto, Julio Zaki; Torricelli, André Augusto Miranda; Lui, Aline Cristina Fioravanti; Guimarães, Sarah Napoli; Nascimento, Heloisa; Regatieri, Caio Vinícius

2018-01-01

To describe optical coherence tomography angiography (OCT-A) findings in patients with retinal vasculitis and to compare them to current fluorescein angiography (FA) findings. This was an observational case series. Nineteen eyes in 10 patients with retinal vasculitis of various etiologies were imaged with FA (TRC-50DX, Topcon) and OCT-A (SD-OCT, Optovue). The images were reviewed and analyzed. The mean age was 36 years (range 24-67 years); there were three males and seven females. The primary vessels involved were veins (89%). Fourteen eyes (74%) had active inflammatory disease during the study period, with signs of vascular sheathing and perivascular leakage on FA. Interestingly, in this group, OCT-A was not able to detect clear signs of active inflammation around the affected vessels. Nevertheless, OCT-A was able to detect secondary lesions in fourteen eyes (74%), including some findings not clearly shown on FA. Most of these were within the macular area. OCT-A was particularly effective in cases of capillary dropout, increased foveal avascular zone, telangiectasias, shunts, and areas of neovascularization. FA remains an essential complementary exam for detection of retinal vasculitis. However, OCT-A extends FA findings and affords better assessment of secondary complications.

Vessel density, retinal thickness, and choriocapillaris vascular flow in myopic eyes on OCT angiography.

PubMed

Milani, Paolo; Montesano, Giovanni; Rossetti, Luca; Bergamini, Fulvio; Pece, Alfredo

2018-06-06

To investigate foveal avascular zone area, macular vascular density, choroidal thickness, and outer retina and choriocapillaris flow in myopic eyes by OCT angiography. Automated macular maps and flow calculations were retrospectively evaluated in 42 myopic and in 40 control eyes. Myopic eyes presented lower whole superficial vessel density (46.4 ± 4.9 vs. 51.6 ± 3.6%, P < 0.0001) and higher flow area in the outer retina (1.3 ± 0.2 vs. 1.1 ± 0.3 mm 2 , P = 0.0012). Between the myopic and non-myopic eyes, no significant differences could be detected in the choriocapillaris perfusion area (1.9 ± 0.07 vs. 1.9 ± 0.05 mm 2 , respectively; P = 0.55) and in the foveal avascular zone area (0.23 ± 0.1 vs. 0.26 ± 0.1 mm 2 , respectively; P = 0.12). The spherical correction positively correlated with superficial vessel density and negatively correlated with outer retina perfusion (P ≤ 0.0021). The superficial vessel density and the local retinal thickness positively correlated at all macular locations (P < 0.005), especially in the foveal region (P < 0.0001). Eyes with high myopia present reduced superficial vascular density and increased outer retina flow. Superficial vascular density and retinal thickness appear to be significantly correlated.

A multi-scale tensor voting approach for small retinal vessel segmentation in high resolution fundus images.

PubMed

Christodoulidis, Argyrios; Hurtut, Thomas; Tahar, Houssem Ben; Cheriet, Farida

2016-09-01

Segmenting the retinal vessels from fundus images is a prerequisite for many CAD systems for the automatic detection of diabetic retinopathy lesions. So far, research efforts have concentrated mainly on the accurate localization of the large to medium diameter vessels. However, failure to detect the smallest vessels at the segmentation step can lead to false positive lesion detection counts in a subsequent lesion analysis stage. In this study, a new hybrid method for the segmentation of the smallest vessels is proposed. Line detection and perceptual organization techniques are combined in a multi-scale scheme. Small vessels are reconstructed from the perceptual-based approach via tracking and pixel painting. The segmentation was validated in a high resolution fundus image database including healthy and diabetic subjects using pixel-based as well as perceptual-based measures. The proposed method achieves 85.06% sensitivity rate, while the original multi-scale line detection method achieves 81.06% sensitivity rate for the corresponding images (p<0.05). The improvement in the sensitivity rate for the database is 6.47% when only the smallest vessels are considered (p<0.05). For the perceptual-based measure, the proposed method improves the detection of the vasculature by 7.8% against the original multi-scale line detection method (p<0.05). Copyright © 2016 Elsevier Ltd. All rights reserved.

Retinal vessel caliber among people with acquired immunodeficiency syndrome: relationships with visual function.

PubMed

Kalyani, Partho S; Fawzi, Amani A; Gangaputra, Sapna; van Natta, Mark L; Hubbard, Larry D; Danis, Ronald P; Thorne, Jennifer E; Holland, Gary N

2012-03-01

To evaluate relationships between retinal vessel caliber and tests of visual function among people with AIDS. Longitudinal, observational cohort study. We evaluated data for participants without ocular opportunistic infections at initial examination (baseline) in the Longitudinal Studies of the Ocular Complications of AIDS (1998-2008). Visual function was evaluated with best-corrected visual acuity, Goldmann perimetry, automated perimetry (Humphrey Field Analyzer), and contrast sensitivity (CS) testing. Semi-automated grading of fundus photographs (1 eye/participant) determined central retinal artery equivalent (CRAE), central retinal vein equivalent (CRVE), and arteriole-to-venule ratio (AVR) at baseline. Multiple linear regression models, using forward selection, sought independent relationships between indices and visual function variables. Included were 1250 participants. Smaller AVR was associated with reduced visual field by Goldmann perimetry (P = .003) and worse mean deviation (P = .02) on automated perimetry and possibly with worse pattern standard deviation (PSD) on automated perimetry (P = .06). There was a weak association between smaller AVR and worse CS (P = .07). Relationships were independent of antiretroviral therapy and level of immunodeficiency (CD4+ T lymphocyte count, human immunodeficiency virus [HIV] RNA blood level). On longitudinal analysis, retinal vascular indices at baseline did not predict changes in visual function. Variation in retinal vascular indices is associated with abnormal visual function in people with AIDS, manifested by visual field loss and possibly by reduced CS. Relationships are consistent with the hypothesis that HIV-related retinal vasculopathy is a contributing factor to vision dysfunction among HIV-infected individuals. Longitudinal studies are needed to determine whether changes in indices predict change in visual function. Copyright © 2012 Elsevier Inc. All rights reserved.

A confocal scanning laser ophthalmoscope for retinal vessel oximetry

NASA Astrophysics Data System (ADS)

Lompado, Arthur

Measurement of a person's blood oxygen saturation has long been recognized as a useful metric for the characterizing ailments ranging from chronic respiratory disorders to acute, potentially life threatening, traumas. The ubiquity of oxygen saturation monitors in the medical field, including portable pulse oximeters and laboratory based CO-oximeters, is a testament to the importance of this technique. The work presented here documents the design, fabrication and development of a unique type of oxygen saturation monitor, a confocal scanning retinal vessel oximeter, with the potential to expand the usefulness of the present devices. A large part of the knowledge base required to construct the instrument comes from the consideration of light scattering by red blood cells in a blood vessel. Therefore, a substantial portion of this work is devoted to the process of light scattering by whole human blood and its effects on the development of a more accurate oximeter. This light scattering effect has been both measured and modeled stochastically to determine its contribution to the measured oximeter signal. It is shown that, although well accepted in the published literature, the model only correlates marginally to the measurements due to inherent limitations imposed by the model assumptions. Nonetheless, enough material has been learned about the scattering to allow development of a mathematical model for the interaction of light with blood in a vessel, and this knowledge has been applied to the data reduction of the present oximeter. This data reduction technique has been tested in a controlled experiment employing a model eye with a blood filled mock retinal vessel. It will be shown that the presently developed technique exhibited strong correlation between the known blood oxygen saturation and that calculated by the new system.

Macular Thickness Variability in Primary Open Angle Glaucoma Patients using Optical Coherence Tomography

PubMed Central

Agarwal, Prakashchand; Sathyan, P; Saini, VK

2014-01-01

ABSTRACT Aim: To compare the difference of retinal macular thickness and macular volume using optical coherence tomography (OCT) in primary open angle glaucoma (POAG) patients with the normal subjects. Materials and methods: This observational case control study included primary open angle glaucoma (POAG) patients (n = 124 eyes) and healthy subjects in the control group (n = 124 eyes). All subjects underwent detailed history, general and systemic exami -nation. Complete ocular examination included best corrected visual acuity (BCVA), slit lamp examination, intraocular pressure (IOP), central corneal thickness, gonioscopy, dilated fundus biomicroscopy. Field analysis was done by white on white Humphrey Field Analyzer (Carl Zeiss). Optical coherence tomography imaging of macular area was performed using Stratus OCT (OCT 3, Version 4, Carl Zeiss Inc, Dublin, California, USA). In both these groups, parameters analyzed were macular thickness, inner macular thicknesses (IMT), outer macular thicknesses (OMT), central macular thick ness (CMT) and total macular volume (TMV). Results: The POAG group had significantly decreased values of TMV, OMT and IMT, compared to control group, while there was no difference in CMT, presumably due to absence of ganglion cells in the central part. Thus, macular thickness and volume parameters may be used for making the diagnosis of glaucoma especially in patients with abnormalities of disc. Conclusion: Macular thickness parameters correlated well with the diagnosis of glaucoma. How to cite this article: Sharma A, Agarwal P, Sathyan P, Saini VK. Macular Thickness Variability in Primary Open Angle Glaucoma Patients using Optical Coherence Tomography. J Current Glau Prac 2014;8(1):10-14. PMID:26997801

Automated detection of retinal nerve fiber layer defects on fundus images: false positive reduction based on vessel likelihood

NASA Astrophysics Data System (ADS)

Muramatsu, Chisako; Ishida, Kyoko; Sawada, Akira; Hatanaka, Yuji; Yamamoto, Tetsuya; Fujita, Hiroshi

2016-03-01

Early detection of glaucoma is important to slow down or cease progression of the disease and for preventing total blindness. We have previously proposed an automated scheme for detection of retinal nerve fiber layer defect (NFLD), which is one of the early signs of glaucoma observed on retinal fundus images. In this study, a new multi-step detection scheme was included to improve detection of subtle and narrow NFLDs. In addition, new features were added to distinguish between NFLDs and blood vessels, which are frequent sites of false positives (FPs). The result was evaluated with a new test dataset consisted of 261 cases, including 130 cases with NFLDs. Using the proposed method, the initial detection rate was improved from 82% to 98%. At the sensitivity of 80%, the number of FPs per image was reduced from 4.25 to 1.36. The result indicates the potential usefulness of the proposed method for early detection of glaucoma.

Retinal angiogenesis suppression through small molecule activation of p53

PubMed Central

Chavala, Sai H.; Kim, Younghee; Tudisco, Laura; Cicatiello, Valeria; Milde, Till; Kerur, Nagaraj; Claros, Nidia; Yanni, Susan; Guaiquil, Victor H.; Hauswirth, William W.; Penn, John S.; Rafii, Shahin; De Falco, Sandro; Lee, Thomas C.; Ambati, Jayakrishna

2013-01-01

Neovascular age-related macular degeneration is a leading cause of irreversible vision loss in the Western world. Cytokine-targeted therapies (such as anti-vascular endothelial growth factor) are effective in treating pathologic ocular angiogenesis, but have not led to a durable effect and often require indefinite treatment. Here, we show that Nutlin-3, a small molecule antagonist of the E3 ubiquitin protein ligase MDM2, inhibited angiogenesis in several model systems. We found that a functional p53 pathway was essential for Nutlin-3–mediated retinal antiangiogenesis and disruption of the p53 transcriptional network abolished the antiangiogenic activity of Nutlin-3. Nutlin-3 did not inhibit established, mature blood vessels in the adult mouse retina, suggesting that only proliferating retinal vessels are sensitive to Nutlin-3. Furthermore, Nutlin-3 inhibited angiogenesis in nonretinal models such as the hind limb ischemia model. Our work demonstrates that Nutlin-3 functions through an antiproliferative pathway with conceivable advantages over existing cytokine-targeted antiangiogenesis therapies. PMID:24018558

Dynamic contrast optical coherence tomography images transit time and quantifies microvascular plasma volume and flow in the retina and choriocapillaris

PubMed Central

Merkle, Conrad W.; Leahy, Conor; Srinivasan, Vivek J.

2016-01-01

Despite the prevalence of optical imaging techniques to measure hemodynamics in large retinal vessels, quantitative measurements of retinal capillary and choroidal hemodynamics have traditionally been challenging. Here, a new imaging technique called dynamic contrast optical coherence tomography (DyC-OCT) is applied in the rat eye to study microvascular blood flow in individual retinal and choroidal layers in vivo. DyC-OCT is based on imaging the transit of an intravascular tracer dynamically as it passes through the field-of-view. Hemodynamic parameters can be determined through quantitative analysis of tracer kinetics. In addition to enabling depth-resolved transit time, volume, and flow measurements, the injected tracer also enhances OCT angiograms and enables clear visualization of the choriocapillaris, particularly when combined with a post-processing method for vessel enhancement. DyC-OCT complements conventional OCT angiography through quantification of tracer dynamics, similar to fluorescence angiography, but with the important added benefit of laminar resolution. PMID:27867732

Dynamic contrast optical coherence tomography images transit time and quantifies microvascular plasma volume and flow in the retina and choriocapillaris.

PubMed

Merkle, Conrad W; Leahy, Conor; Srinivasan, Vivek J

2016-10-01

Despite the prevalence of optical imaging techniques to measure hemodynamics in large retinal vessels, quantitative measurements of retinal capillary and choroidal hemodynamics have traditionally been challenging. Here, a new imaging technique called dynamic contrast optical coherence tomography (DyC-OCT) is applied in the rat eye to study microvascular blood flow in individual retinal and choroidal layers in vivo . DyC-OCT is based on imaging the transit of an intravascular tracer dynamically as it passes through the field-of-view. Hemodynamic parameters can be determined through quantitative analysis of tracer kinetics. In addition to enabling depth-resolved transit time, volume, and flow measurements, the injected tracer also enhances OCT angiograms and enables clear visualization of the choriocapillaris, particularly when combined with a post-processing method for vessel enhancement. DyC-OCT complements conventional OCT angiography through quantification of tracer dynamics, similar to fluorescence angiography, but with the important added benefit of laminar resolution.

Retinal vascular injuries and intravitreal human embryonic stem cell-derived haemangioblasts.

PubMed

Wang, Jin-Da; An, Ying; Zhang, Jing-Shang; Wan, Xiu-Hua; Zhang, Wei; Lanza, Robert; Lu, Shi-Jiang; Jonas, Jost B; Xu, Liang

2017-09-01

To investigate whether intravitreally applied haemangioblasts (HB) derived from human embryonic stem cells (hESCs) are helpful for the repair of vascular damage caused in animals by an oxygen-induced retinopathy (OIR), by an induced diabetic retinopathy (DR) or by an induced retinal ischaemia with subsequent reperfusion. Human embryonic stem cell-derived HBs were transplanted intravitreally into C57BL/6J mice (OIR model), into male Wistar rats with an induced DR and into male Wistar rats undergoing induced retinal ischaemia with subsequent reperfusion. Control groups of animals received an intravitreal injection of endothelial cells (ECs) or phosphate-buffered saline (PBS). We examined the vasculature integrity in the mice with OIR, the blood-retina barrier in the rats with induced DR, and retinal thickness and retinal ganglion cell density in retina flat mounts of the rats with the retinal ischaemic-reperfusion retinopathy. In the OIR model, the study group versus control groups showed a significantly (p < 0.001) smaller retinal avascular area [5.1 ± 2.7%;n = 18 animals versus 12.2 ± 2.8% (PBS group; n = 10 animals) and versus 11.8 ± 3.7% (EC group; n = 8 animals)] and less retinal neovascularization [6.3 ± 2.5%;n = 18 versus 15.2 ± 6.3% (n = 10; PBS group) and versus 15.8 ± 3.3% (n = 8; EC group)]. On retinal flat mounts, hESC-HBs were integrated into damaged retinal vessels and stained positive for PECAM (CD31) as EC marker. In the DR model, the study group versus the EC control group showed a significantly (p = 0.001) better blood-retina barrier function as measured at 2 days after the intravitreal injections [study group: 20.2 ± 12.8 μl/(g × hr); n = 6; versus EC control group: 52.9 ± 9.9 μl/(g × hr; n = 6)]. In the retinal ischaemia-reperfusion model, the groups did not differ significantly in retinal thickness and retinal ganglion cell density at 2, 5 and 7 days after baseline. By integrating into damaged retinal vessels and differentiating into ECs, intravitreally administered hESC-HBs may have partially repaired a retinal vascular injury caused by OIR model and DR. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Detection of hypertensive retinopathy using vessel measurements and textural features.

PubMed

Agurto, Carla; Joshi, Vinayak; Nemeth, Sheila; Soliz, Peter; Barriga, Simon

2014-01-01

Features that indicate hypertensive retinopathy have been well described in the medical literature. This paper presents a new system to automatically classify subjects with hypertensive retinopathy (HR) using digital color fundus images. Our method consists of the following steps: 1) normalization and enhancement of the image; 2) determination of regions of interest based on automatic location of the optic disc; 3) segmentation of the retinal vasculature and measurement of vessel width and tortuosity; 4) extraction of color features; 5) classification of vessel segments as arteries or veins; 6) calculation of artery-vein ratios using the six widest (major) vessels for each category; 7) calculation of mean red intensity and saturation values for all arteries; 8) calculation of amplitude-modulation frequency-modulation (AM-FM) features for entire image; and 9) classification of features into HR and non-HR using linear regression. This approach was tested on 74 digital color fundus photographs taken with TOPCON and CANON retinal cameras using leave-one out cross validation. An area under the ROC curve (AUC) of 0.84 was achieved with sensitivity and specificity of 90% and 67%, respectively.

Multimodality optical coherence tomography and fluorescence confocal scanning laser ophthalmoscopy in a zebrafish model of retinal vascular occlusion and remodeling

NASA Astrophysics Data System (ADS)

Li, Xiaoyue; Spitz, Kathleen; Bozic, Ivan; Tao, Yuankai K.

2018-02-01

Neovascularization in diabetic retinopathy (DR) and age-related macular degeneration (AMD) result in severe vision-loss and are two of the leading causes of blindness. The structural, metabolic, and vascular changes underlying retinal neovascularization are unknown and, thus, there is an unmet need to identify mechanisms of pathogenesis and novel anti-angiogenic therapies. Zebrafish is a robust ophthalmological model because its retina has comparable structure to the human retina and its fecundity and life-cycle enable development of mutant phenotypes of human pathologies. Here, we perform multimodal imaging with OCT and fluorescence confocal scanning laser ophthalmoscopy (cSLO) to identify changes in retinal structure and function in a zebrafish model of vascular leakage. Transgenic zebrafish with EGFP tagged plasma protein were imaged longitudinally at six time points over two weeks to visualize vascular perfusion changes from diethylaminobenzaldehyde (DEAB) treatment. Complementary contrast from OCT-A perfusion maps and cSLO imaging of plasma protein EGFP shows vascular occlusions posttreatment. cSLO images confirm presence of vessels despite loss of OCT-A signal. Plasma protein EGFP contrast also shows significant changes in vessel structure as compared to baseline images. OCT structural volumes show empty vessel cross-sections confirming non-perfusion. In addition, we present algorithms for automated biometric identification of OCT datasets using OCT-A vascular patterns in the presence of significant vascular perfusion changes. These results establish a framework for large-scale in vivo assays to identify novel anti-angiogenic compounds and understand the mechanisms ofneovascularization associated with retinal ocular pathologies.

A Comparative Study on Preprocessing Techniques in Diabetic Retinopathy Retinal Images: Illumination Correction and Contrast Enhancement

PubMed Central

Rasta, Seyed Hossein; Partovi, Mahsa Eisazadeh; Seyedarabi, Hadi; Javadzadeh, Alireza

2015-01-01

To investigate the effect of preprocessing techniques including contrast enhancement and illumination correction on retinal image quality, a comparative study was carried out. We studied and implemented a few illumination correction and contrast enhancement techniques on color retinal images to find out the best technique for optimum image enhancement. To compare and choose the best illumination correction technique we analyzed the corrected red and green components of color retinal images statistically and visually. The two contrast enhancement techniques were analyzed using a vessel segmentation algorithm by calculating the sensitivity and specificity. The statistical evaluation of the illumination correction techniques were carried out by calculating the coefficients of variation. The dividing method using the median filter to estimate background illumination showed the lowest Coefficients of variations in the red component. The quotient and homomorphic filtering methods after the dividing method presented good results based on their low Coefficients of variations. The contrast limited adaptive histogram equalization increased the sensitivity of the vessel segmentation algorithm up to 5% in the same amount of accuracy. The contrast limited adaptive histogram equalization technique has a higher sensitivity than the polynomial transformation operator as a contrast enhancement technique for vessel segmentation. Three techniques including the dividing method using the median filter to estimate background, quotient based and homomorphic filtering were found as the effective illumination correction techniques based on a statistical evaluation. Applying the local contrast enhancement technique, such as CLAHE, for fundus images presented good potentials in enhancing the vasculature segmentation. PMID:25709940

Differences in Pre and Post Vascular Patterning Within Retinas from ISS Crew Members and Head-Down Tilt (HDT) Subjects by VESGEN Analysis

NASA Technical Reports Server (NTRS)

Murray, M. C.; Vizzeri, G.; Taibbi, G.; Mason, S. S.; Young, M.; Zanello, S. B.; Parsons-Wingerter, P.

2018-01-01

Accelerated research by NASA has investigated the significant risks incurred during long-duration missions in microgravity for Space Flight-Associated Neuro-ocular Syndrome (SANS, formerly known as Visual Impairments associated with Increased Intracranial Pressure, VIIP) [1]. For our study, NASA's VESsel GENeration Analysis (VESGEN) was used to investigate the role of retinal blood vessels in the etiology of SANS/VIIP. The response of retinal vessels to microgravity was evaluated in astronaut crew members pre and post flight to the International Space Station (ISS), and compared to the response of retinal vessels in healthy volunteers to 6deg head-down tilt during 70 days of bed rest (HDTBR). For the study, we are testing the hypothesis that long-term cephalad fluid shifts resulting in ocular and visual impairments are necessarily mediated in part by retinal blood vessels, and therefore are accompanied by structural adaptations of the vessels. METHODS: Vascular patterns in the retinas of crew members and HDTBR subjects extracted from 30deg infrared (IR) Heidelberg Spectralis images collected pre/postflight and pre/post HDTBR, respectively, were analyzed by VESGEN (patent pending). VESGEN is a mature, automated software developed as a research discovery tool for progressive vascular diseases in the retina and other tissues. The multi-parametric VESGEN analysis generates maps of branching arterial and venous trees quantified by parameters such as the fractal dimension (Df, a modern measure of vascular space-filling capacity), vessel diameters, and densities of vessel length and number classified into specific branching generations according to vascular physiological branching rules. The retrospective study approved by NASA's Institutional Review Board included the analysis of bilateral retinas in eight ISS crew members monitored by routine occupational surveillance and six HDTBR subjects (NASA FARU Campaign 11, for example). The VESGEN analysis was conducted in a blinded fashion, with IR retinal images masked to the subject's identity, ophthalmic and clinical characteristics, and to the temporal sequence of image collection. To complete our study, VESGEN results will be analyzed statistically and correlated with other ophthalmic and medical findings. RESULTS: Preliminary results for changes in the pre to post status of vascular patterning in the retinas of crew members and HDTBR subjects are interestingly opposite. By Df and other vascular branching measures, the space-filling capacity of arterial and venous trees decreased in the majority of crew members (11/16 retinas). In contrast, vascular densities increased in HDTBR subjects by the same parameters (6/10 retinas). To conclude the study, biostatistics and medical analyses will be conducted to quantify and draw conclusions about how the changes associated with flight compare to those associated with HDTBR. CONCLUSIONS: Vascular densities appeared to decrease in the retinas of ISS crew members and increase in HDTBR subjects. Differences in arterial and venous response to cephalad fluid shifts induced by ISS and HDTBR may have resulted from a long-duration conditioning phenomenon (for example, 6-month ISS missions compared to 70 days HDTBR), or the presence of gravity in HDTBR compared to microgravity on the ISS. In addition, increased and decreased vessel diameters for Crew Members and HDTBR, respectively, are subject to limits of im

Differences in Pre and Post Vascular Patterning of Retinas from ISS Crew Members and HDT Subjects by VESGEN Analysis

NASA Technical Reports Server (NTRS)

Murray, M. C.; Vizzeri, G.; Taibbi, G.; Mason, S. S.; Young, M. H.; Zanello, S. B.; Parsons-Wingerter, P. A.

2018-01-01

Accelerated research by NASA [1] has investigated the significant risks for visual and ocular impairments Spaceflight Associated Neuro-Ocular Syndrome /Visual Impairment/Intracranial Pressure (SANS/VIIP) incurred by microgravity spaceflight, especially long-duration missions. Our study investigates the role of blood vessels in the incidence and etiology of SANS/VIIP within the retinas of Astronaut crewmembers pre-and post-flight to the International Space Station (ISS) by NASA's VESsel GENeration Analysis (VESGEN). The response of retinal vessels in crewmembers to microgravity was compared to that of retinal vessels to Head-Down Tilt (HDT) in subjects undergoing 70-Day Bed Rest. The study tests the proposed hypothesis that cephalad fluid shifts missions, resulting in ocular and visual impairments, are necessarily mediated in part by retinal blood vessels, and are therefore accompanied by significant remodeling of retinal vasculature.Vascular patterns in the retinas of crew members and HDTBR subjects extracted from 30° infrared (IR) Heidelberg Spectralis® images collected pre/postflight and pre/post HDTBR, respectively, were analyzed by VESGEN (patent pending). a mature, automated software developed as a research discovery tool for progressive vascular diseases in the retina and other tissues [2]. The weighted, multi-parametric VESGEN analysis generates maps of branching arterial and venous trees and quantification by parameters such as the fractal dimension (Df, a modern measure of vascular space-filling capacity), vessel diameters, and densities of vessel length and number classified into specific branching generations by vascular physiological branching rules [2,3]. The retrospective study approved by NASA’s Institutional Review Board included six HDT subjects (NASA Flight Analogs Research Unit [FARU] Campaign 11; for example, [4]) and eight ISS crewmembers monitored by routine occupational surveillance who provided their study consents to NASA’s Lifetime Surveillance of Astronaut Health (LSAH). For the initial blinded VESGEN phase, ophthalmic retinal images were masked as to subject identity and pre- and post-status. In the second unblinded phase, VESGEN results were analyzed according to the pre- and post-status of left and right retinas matched to each subject. To complete our study, vascular results will be subjected to NASA biostatistical analysis and correlated with other ophthalmic and medical findings. Preliminary results for changes in the pre- to post-status of vascular patterning in the retinas of crewmembers and HDT subjects are strikingly opposite. By Df and other vascular branching measures, the space-filling capacity of arterial and venous trees decreased in a substantial subset of crewmembers (11/16 retinas). In contrast, vascular densities increased in a substantial subset of HDT subjects by the same parameters (6/10 retinas, currently excluding one anomalous subject). To conclude the study, biostatistical and medical analyses will be of critical importance for investigating the validity of these vascular findings. Vascular densities appeared to decrease in the retinas of crewmembers following ISS Missions, and increase in subjects after HDT. The vascular increases and decreases most likely derive primarily from limits of resolution to the ophthalmic imaging that does not capture the smallest vessels, rather than from vessel growth or atrophy. Differences in arterial and venous response to cephalad fluid shifts induced by ISS and HDT may have resulted from a long-duration conditioning phenomenon (for example, 6-month ISS missions compared to 70-day HDT), or the presence of gravity in HDT compared to microgravity onboard the ISS. To conclude our study, the biostatistical and medical analyses will be of critical importance for investigating the validity and significance of the VESGEN findings.

Development of Choroidal Neovascularization in rats with Advanced Intense Cyclic Light-induced Retinal Degeneration

PubMed Central

Albert, Daniel M.; Neekhra, Aneesh; Wang, Shoujian; Darjatmoko, Soesiawati R.; Sorenson, Christine M.; Dubielzig, Richard R.; Sheibani, Nader

2010-01-01

Objective To study the progressive changes of intense cyclic light-induced retinal degeneration and determine whether it results in choroidal neovascularization (CNV). Methods Albino rats were exposed to 12 h of 3000 lux cyclic light for 1, 3, or 6 months. Prior to euthanization, fundus examination, fundus photographs, fluorescein and indocyanine green angiography, and Optical Coherence Tomography (OCT) evaluations were performed. Light exposed animals were euthanized after 1, 3, or 6 months for histopathological evaluation. Retinas were examined for the presence of 4-hydroxy-2-nonenal (HNE) and nitrotyrosine modified proteins by immunofluorescence staining. Results Chronic intense cyclic light exposure resulted in retinal degeneration with loss of the outer segments of photoreceptors and approximately two-thirds of the outer nuclear layer (ONL) and development of sub-retinal pigment epithelium (RPE) neovascularization after 1 month. Almost the entire ONL was absent with the presence of CNV, which penetrated Bruch’s membrane and extended into the outer retina after 3 months. Absence of the ONL, multiple foci of CNV, RPE fibrous metaplasia, and connective tissue bands containing blood vessels extending into the retina were observed after 6 months. All intense light exposed animals showed an increased presence of HNE and nitrotyrosine staining. OCT and angiographic studies confirmed retinal thinning and leakiness of the newly fromed blood vessels. Conclusions Our results suggest albino rats develop progressive stages of retinal degeneration and CNV after chronic intense cyclic light exposure allowing the detailed study of the pathogenesis and treatment of age-related macular degeneration. PMID:20142545

Hypoxia-Induced Retinal Neovascularization in Zebrafish Embryos: A Potential Model of Retinopathy of Prematurity

PubMed Central

Kao, Alex; Hsi, Brian; Lee, Shwu-Huey; Chen, Yau-Hung; Wang, I-Jong

2015-01-01

Retinopathy of prematurity, formerly known as a retrolental fibroplasia, is a leading cause of infantile blindness worldwide. Retinopathy of prematurity is caused by the failure of central retinal vessels to reach the retinal periphery, creating a nonperfused peripheral retina, resulting in retinal hypoxia, neovascularization, vitreous hemorrhage, vitreoretinal fibrosis, and loss of vision. We established a potential retinopathy of prematurity model by using a green fluorescent vascular endothelium zebrafish transgenic line treated with cobalt chloride (a hypoxia-inducing agent), followed by GS4012 (a vascular endothelial growth factor inducer) at 24 hours postfertilization, and observed that the number of vascular branches and sprouts significantly increased in the central retinal vascular trunks 2–4 days after treatment. We created an angiography method by using tetramethylrhodamine dextran, which exhibited severe vascular leakage through the vessel wall into the surrounding retinal tissues. The quantification of mRNA extracted from the heads of the larvae by using real-time quantitative polymerase chain reaction revealed a twofold increase in vegfaa and vegfr2 expression compared with the control group, indicating increased vascular endothelial growth factor signaling in the hypoxic condition. In addition, we demonstrated that the hypoxic insult could be effectively rescued by several antivascular endothelial growth factor agents such as SU5416, bevacizumab, and ranibizumab. In conclusion, we provide a simple, highly reproducible, and clinically relevant retinopathy of prematurity model based on zebrafish embryos; this model may serve as a useful platform for clarifying the mechanisms of human retinopathy of prematurity and its progression. PMID:25978439

Presumed atypical HDR syndrome associated with Band Keratopathy and pigmentary retinopathy.

PubMed

Kim, Cinoo; Cheong, Hae Il; Kim, Jeong Hun; Yu, Young Suk; Kwon, Ji Won

2011-01-01

This report describes presumed atypical hypoparathyroidism, deafness, and renal dysplasia (HDR) syndrome associated with unexpected ocular findings. The patient had exotropia, bilateral band keratopathy, and pigmentary retinopathy, including attenuated retinal vessels and atrophy of the retinal pigment epithelium. Even though the calcific plaques were successfully removed, visual acuity in both eyes gradually decreased and electroretinography was extinguished. Copyright 2009, SLACK Incorporated.

Retinopathy and Cognitive Impairment in Adults With CKD

PubMed Central

Yaffe, Kristine; Ackerson, Lynn; Hoang, Tina D.; Go, Alan S.; Maguire, Maureen G.; Ying, Gui-Shuang; Daniel, Ebenezer; Bazzano, Lydia A.; Coleman, Martha; Cohen, Debbie L.; Kusek, John W.; Ojo, Akinlolu; Seliger, Stephen; Xie, Dawei; Grunwald, Juan E.

2014-01-01

Background Retinal microvascular abnormalities have been associated with cognitive impairment, possibly serving as a marker of cerebral small vessel disease. This relationship has not been evaluated among persons with chronic kidney disease (CKD), a condition associated with increased risk of both retinal pathology and cognitive impairment. Study Design Cross-sectional study Setting & Participants 588 participants ≥ 52 years old with CKD in the Chronic Renal Insufficiency Cohort (CRIC) Study Predictor Retinopathy graded using the Early Treatment Diabetic Retinopathy Study severity scale and diameters of retinal vessels. Outcomes Neuropsychological battery of six cognitive tests Measurements Logistic regression models were used to evaluate the association of retinopathy, individual retinopathy features, and retinal vessel diameters with cognitive impairment (≤1 SD from the mean), and linear regression models were used to compare cognitive test scores across levels of retinopathy adjusting for age, race, sex, education, and medical comorbidities. Results The mean age of the cohort was 65.3 +/− 5.6 (SD) years; 51.9% were non-White, and 52.6% were male. The prevalence of retinopathy was 30.1% and 14.3% for cognitive impairment. Compared to those without retinopathy, participants with retinopathy had increased likelihood of cognitive impairment on executive function (35.1% vs. 11.5%; OR, 3.4; 95% CI, 2.0-6.0), attention (26.7% vs. 7.3%; OR, 3.0; 95% CI, 1.8-4.9), and naming (26.0% vs. 10.0%; OR, 2.1; 95% CI, 1.2-3.4) after multivariable adjustment. Increased level of retinopathy was also associated with lower cognitive performance on executive function and attention. Microaneurysms were associated with cognitive impairment on some domains, but there were no significant associations with other retinal measures after multivariable adjustment. Limitations Unknown temporal relationship between retinopathy and impairment. Conclusions In adults with CKD, retinopathy is associated with poor performance on several cognitive domains including executive function and attention. Evaluation of retinal microvascular abnormalities may be a promising tool for identifying patients with CKD who are at increased risk of cognitive impairment. PMID:23206534

Association of consumption of dairy products and meat with retinal vessel calibers in subjects at increased cardiovascular risk.

PubMed

Karatzi, K; Aissopou, E K; Tsirimiagou, C; Fatmeli, E; Sfikakis, P P; Protogerou, A D

2016-08-01

Association of dairy products and meat consumption with macrocirculation is previously described, but such association with microcirculation is poorly investigated. We aimed to test the hypothesis that the consumption of high- and low-fat dairy products as well as red, white, and processed meat is associated with retinal vessel calibers in adults at an increased risk of cardiovascular disease (CVD). In consecutive subjects (n = 181, age: 51.3 ± 12.4 years, 51.4% women) without CVD and diabetes mellitus but with increased CVD risk, we obtained digital left and right retinal images. These images were assessed with validated software to determine central retinal arteriolar and venular equivalents and the arteriolar to venular ratio (CRAE, CRVE, and AVR, respectively). The consumption of dairy products and meat was assessed through 24-h recalls in all volunteers. After adjustment for potential confounders, the following findings were obtained: (i) low-fat milk and yogurt were positively associated with CRAE (b=0.145, p=0.031 left; b=0.141, p=0.038 right) and inversely associated with CRVE (b=-0.155, p=0.026 left; b=-0.146, p=0.041 right); (ii) low-fat cheese was positively associated with CRAE (b=0.164, p=0.011 left and b=0.155, p=0.017 right); and (iii) red meat was inversely associated with CRAE (b=-0.143, p=0.032 left; b=-0.114, p=0.050 right). High-fat milk, yogurt, and cheese or white and processed meat were not found to be associated with retinal vessel calibers. High consumption of low-fat milk, yogurt, and cheese and low consumption of red meat could be beneficial for retinal microvascular health. Prospective studies are needed to verify these findings. Copyright © 2016 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.

Long-term Effect of Panretinal Photocoagulation on Spectral Domain Optical Coherence Tomography Measurements in Diabetic Retinopathy.

PubMed

Lee, Haeng-Jin; Kang, Tae-Seen; Kwak, Baek-Soo; Jo, Young-Joon; Kim, Jung-Yeul

2017-08-01

To evaluate the effects of panretinal photocoagulation on spectral domain optical coherence tomography measurements in diabetic retinopathy by comparing the thicknesses of the central macula, retinal nerve fiber layer, and ganglion cell layer, we used a Cirrus HD OCT® (Carl Zeiss Meditec, Dublin, CA, USA) in normal and diabetic retinopathy cohorts. We analyzed patients who visited our retinal clinic between May 2013 and July 2014. The patients were classified into four groups: normal (Group A), diabetes without diabetic retinopathy (Group B), severe nonproliferative or proliferative diabetic retinopathy (Group C), and at least 3 years after panretinal photocoagulation treatment (Group D). The mean thicknesses of the macula, retinal nerve fiber layer, and ganglion cell layer in each group were compared by measuring a macular cube 512 × 128 scan and an optic disc cube 200 × 200 scan twice. In total, 154 patients were enrolled. The mean thickness of the central macula in groups A to D was 257.2, 256.8, 257.4, and 255.6 µm, respectively, and did not differ significantly. The mean thickness of the RNFL in group A to D was 96.8, 96.5, 97.2, and 92.8 µm, respectively, and was significantly lower in group D (decreased in the inferior, superior, and nasal sectors, but increased in the temporal). The mean thickness of the ganglion cell layer was also significantly lower in group D (A, 84.5 µm; B, 84.4 µm; C, 82.5 µm; D, 78.5 µm). The mean thicknesses of the retinal nerve fiber and ganglion cell layers were decreased significantly in eyes with diabetic eye disease treated with panretinal photocoagulation compared to normal or eyes with diabetic eye disease that had not been laser-treated. Laser treatment might have altered the thickness of the inner layer of the retina, and such changes should be considered in diabetic retinopathy patients after panretinal photocoagulation treatment.

Photocoagulation in rabbits: optical coherence tomographic lesion classification, wound healing reaction, and retinal temperatures.

PubMed

Koinzer, Stefan; Hesse, Carola; Caliebe, Amke; Saeger, Mark; Baade, Alexander; Schlott, Kerstin; Brinkmann, Ralf; Roider, Johann

2013-09-01

The rabbit is the most common animal model to study retinal photocoagulation lesions. We present a classification of retinal lesions from rabbits, that is based on optical coherence tomographic (OCT) findings, temperature data, and OCT-follow-up data over 3 months. Four hundred eighty-six photocoagulation lesions (modified Zeiss Visulas® 532 nm CW laser, lesion diameter 133 µm, exposure duration 200  milliseconds or variable, power variable) were analyzed from six eyes of three chinchilla gray rabbits. During the irradiation of each lesion, we used an optoacoustics-based method to measure the retinal temperature profile. Two hours, 1 week, 1 month, and 3 months after the treatment, we obtained fundus color and OCT (Spectralis®) images of each lesion. We classified the lesions according to their OCT morphology and correlated the findings to ophthalmoscopic and OCT lesion diameters, and temperatures. Besides an undetectable lesion class 0, we discerned subthreshold lesions that were invisible on the fundus but detectable in OCT (classes 1 and 2), very mild lesions that were partly visible on the fundus (class 3), and 3 classes of suprathreshold lesions. OCT greatest linear diameters (GLDs) were larger than ophthalmoscopic lesion diameters, both increased for increasing classes, and GLDs decreased over 3 months within each class. Mean peak end temperatures for 200  milliseconds lesions ranged from 61°C in class 2 to 80°C in class 6. The seven step rabbit lesion classifier is distinct from a previously published human lesion classifier. Threshold lesions are generated at comparable temperatures in rabbits and humans, while more intense lesions are created at lower temperatures in rabbits. The OCT lesion classifier could replace routine histology in some studies, and the presented data may be used to estimate lesion end temperatures from OCT images. © 2013 Wiley Periodicals, Inc.

Novel Fluorescein Angiography-Based Computer-Aided Algorithm for Assessment of Retinal Vessel Permeability

PubMed Central

Chassidim, Yoash; Parmet, Yisrael; Tomkins, Oren; Knyazer, Boris; Friedman, Alon; Levy, Jaime

2013-01-01

Purpose To present a novel method for quantitative assessment of retinal vessel permeability using a fluorescein angiography-based computer algorithm. Methods Twenty-one subjects (13 with diabetic retinopathy, 8 healthy volunteers) underwent fluorescein angiography (FA). Image pre-processing included removal of non-retinal and noisy images and registration to achieve spatial and temporal pixel-based analysis. Permeability was assessed for each pixel by computing intensity kinetics normalized to arterial values. A linear curve was fitted and the slope value was assigned, color-coded and displayed. The initial FA studies and the computed permeability maps were interpreted in a masked and randomized manner by three experienced ophthalmologists for statistical validation of diagnosis accuracy and efficacy. Results Permeability maps were successfully generated for all subjects. For healthy volunteers permeability values showed a normal distribution with a comparable range between subjects. Based on the mean cumulative histogram for the healthy population a threshold (99.5%) for pathological permeability was determined. Clear differences were found between patients and healthy subjects in the number and spatial distribution of pixels with pathological vascular leakage. The computed maps improved the discrimination between patients and healthy subjects, achieved sensitivity and specificity of 0.974 and 0.833 respectively, and significantly improved the consensus among raters for the localization of pathological regions. Conclusion The new algorithm allows quantification of retinal vessel permeability and provides objective, more sensitive and accurate evaluation than the present subjective clinical diagnosis. Future studies with a larger patients’ cohort and different retinal pathologies are awaited to further validate this new approach and its role in diagnosis and treatment follow-up. Successful evaluation of vasculature permeability may be used for the early diagnosis of brain microvascular pathology and potentially predict associated neurological sequelae. Finally, the algorithm could be implemented for intraoperative evaluation of micovascular integrity in other organs or during animal experiments. PMID:23626701

Optical Coherence Tomography Angiography of Retinal Cavernous Hemangioma.

PubMed

Pierro, Luisa; Marchese, Alessandro; Gagliardi, Marco; Bandello, Francesco

2017-08-01

Retinal cavernous hemangioma is a rare, benign, retinal tumor characterized by angiomatous proliferation of vessels within the inner retina or the optic disc.1 Here we report a case of retinal cavernous hemangioma on the margin of the optic disc in the right eye of a 61-year-old asymptomatic female. The lesion was studied with multimodal imaging which included structural optical coherence tomography, fluorescein angiography, blue fundus auto-fluorescence, optical coherence tomography angiography (OCTA) (DRI OCT Triton; Topcon, Tokyo, Japan) and visual field examination. Blood circulation inside retinal cavernous hemangioma lesion is typically low-stagnant.2 However, OCTA demonstrated blood flow inside the lesion, illustrating its vascular circulation.3 Visual field was within the normal limits, except from a slight enlargement of the blind spot. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:684-685.]. Copyright 2017, SLACK Incorporated.

A rare type of Usher's syndrome.

PubMed

Antunica, Antonela Gverović; Kastelan, Snjezana; Bućan, Kajo; Ivanković, Mira; Radman, Maja; Karaman, Ksenija

2013-12-01

A case is presented of a very rare type of Usher's syndrome detected in a 30-year-old woman in her 28th week of pregnancy. She reported left eye visual impairment with a one-month history. She underwent standard ophthalmologic examination with additional procedures scheduled after childbirth, including fluorescein angiography, visual field (Goldman and Octopus) and electroretinography. Fundus examination revealed pallor of the optic disk, diffuse retinal blood vessel narrowing, no retinal pigmentation, left macular edema, vitreous liquefaction, and posterior vitreous detachment. Goldman perimetry showed narrowing of all isopters to 10 degrees, and Octopus perimetry showed peripheral decrease of retinal sensitivity. Electroretinography confirmed the diagnosis of retinitis pigmentosa sine pigmento. Upon collecting case history records, hearing disorders originating from childhood were discovered. To our knowledge, this type of retinitis in Usher's syndrome has been reported only once in the available literature.

Identification of suitable fundus images using automated quality assessment methods.

PubMed

Şevik, Uğur; Köse, Cemal; Berber, Tolga; Erdöl, Hidayet

2014-04-01

Retinal image quality assessment (IQA) is a crucial process for automated retinal image analysis systems to obtain an accurate and successful diagnosis of retinal diseases. Consequently, the first step in a good retinal image analysis system is measuring the quality of the input image. We present an approach for finding medically suitable retinal images for retinal diagnosis. We used a three-class grading system that consists of good, bad, and outlier classes. We created a retinal image quality dataset with a total of 216 consecutive images called the Diabetic Retinopathy Image Database. We identified the suitable images within the good images for automatic retinal image analysis systems using a novel method. Subsequently, we evaluated our retinal image suitability approach using the Digital Retinal Images for Vessel Extraction and Standard Diabetic Retinopathy Database Calibration level 1 public datasets. The results were measured through the F1 metric, which is a harmonic mean of precision and recall metrics. The highest F1 scores of the IQA tests were 99.60%, 96.50%, and 85.00% for good, bad, and outlier classes, respectively. Additionally, the accuracy of our suitable image detection approach was 98.08%. Our approach can be integrated into any automatic retinal analysis system with sufficient performance scores.

Oxygen-induced retinopathy in mice with retinal photoreceptor cell degeneration.

PubMed

Zhang, Qian; Zhang, Zuo-Ming

2014-04-25

It is reported that retinal neovascularization seems to rarely co-exist with retinitis pigmentosa in patients and in some mouse models; however, it is not widely acknowledged as a universal phenomenon in all strains of all animal species. We aimed to further explore this phenomenon with an oxygen-induced retinopathy model in mice with retinal photoreceptor cell degeneration. Oxygen-induced retinopathy of colored and albino mice with rapid retinal degeneration were compared to homologous wild-type mice. The retinas were analyzed using high-molecular-weight FITC-dextran stained flat-mount preparation, hematoxylin and eosin (H&E) stained cross-sections, an immunohistochemical test for vascular endothelial growth factor (VEGF) distribution and Western blotting for VEGF expression after exposure to hyperoxia between postnatal days 17 (P17) and 21. Leakage and areas of non-perfusion of the retinal blood vessels were alleviated in the retinal degeneration mice. The number of preretinal vascular endothelial cell nuclei in the retinal degeneration mice was smaller than that in the homologous wild-type mice after exposure to hyperoxia (P<0.01). The degree of oxygen-induced retinopathy was positively correlated with the VEGF expression level. However, the VEGF expression level was lower in the retinal degeneration mice. Proliferative retinopathy occurred in mice with rapid retinal degeneration, but retinal photoreceptor cell degeneration could partially restrain the retinal neovascularization in this rapid retinal degeneration mouse model. Copyright © 2014 Elsevier Inc. All rights reserved.

Design of Content Based Image Retrieval Scheme for Diabetic Retinopathy Images using Harmony Search Algorithm.

PubMed

Sivakamasundari, J; Natarajan, V

2015-01-01

Diabetic Retinopathy (DR) is a disorder that affects the structure of retinal blood vessels due to long-standing diabetes mellitus. Automated segmentation of blood vessel is vital for periodic screening and timely diagnosis. An attempt has been made to generate continuous retinal vasculature for the design of Content Based Image Retrieval (CBIR) application. The typical normal and abnormal retinal images are preprocessed to improve the vessel contrast. The blood vessels are segmented using evolutionary based Harmony Search Algorithm (HSA) combined with Otsu Multilevel Thresholding (MLT) method by best objective functions. The segmentation results are validated with corresponding ground truth images using binary similarity measures. The statistical, textural and structural features are obtained from the segmented images of normal and DR affected retina and are analyzed. CBIR in medical image retrieval applications are used to assist physicians in clinical decision-support techniques and research fields. A CBIR system is developed using HSA based Otsu MLT segmentation technique and the features obtained from the segmented images. Similarity matching is carried out between the features of query and database images using Euclidean Distance measure. Similar images are ranked and retrieved. The retrieval performance of CBIR system is evaluated in terms of precision and recall. The CBIR systems developed using HSA based Otsu MLT and conventional Otsu MLT methods are compared. The retrieval performance such as precision and recall are found to be 96% and 58% for CBIR system using HSA based Otsu MLT segmentation. This automated CBIR system could be recommended for use in computer assisted diagnosis for diabetic retinopathy screening.

Why choroid vessels appear dark in clinical OCT images

NASA Astrophysics Data System (ADS)

Kirby, Mitchell A.; Li, Chenxi; Choi, Woo June; Gregori, Giovanni; Rosenfeld, Philip; Wang, Ruikang

2018-02-01

With the onset of clinically available spectral domain (SD-OCT) and swept source (SS-OCT) systems, clinicians are now easily able to recognize sub retinal microstructure and vascularization in the choroidal and scleral regions. As the bloodrich choroid supplies nutrients to the upper retinal layers, the ability to monitor choroid function accurately is of vital importance for clinical assessment of retinal health. However, the physical appearance of the choroid blood vessels (darker under a healthy Retinal Pigmented Epithelium (RPE) compared to regions displaying an RPE atrophic lesion) has led to confusion within the OCT ophthalmic community. The differences in appearance between each region in the OCT image may be interpreted as different vascular patterns when the vascular networks are in fact very similar. To explain this circumstance, we simulate light scattering phenomena in the RPE and Choroid complexes using the finite difference time domain (FDTD) method. The simulation results are then used to describe and validate imaging features in a controlled multi-layered tissue phantom designed to replicate human RPE, choroid, and whole blood microstructure. Essentially, the results indicate that the strength of the OCT signal from choroidal vasculature is dependent on the health and function of the RPE, and may not necessarily directly reflect the health and function of the choroidal vasculature.

The effect of acetazolamide on different ocular vascular beds.

PubMed

Haustein, Michael; Spoerl, Eberhard; Boehm, Andreas G

2013-05-01

To assess the effect of acetazolamide (AZ) on different ocular vascular beds. In a prospective study, 32 healthy volunteers (16 male, 16 female) with a mean age of 23.9 ± 3.3 years (20-39 years) were included. Before and after intravenous administration of 1,000 mg AZ (single dose), ocular microcirculation parameters were measured every 20 min for 2 h. Retinal vessel diameters (VD) were measured by the retina vessel analyzer, blood flow (BF) in the neuroretinal rim by the laser doppler flowmeter according to Riva, and the parapapillary retinal BF by the scanning laser Doppler flowmeter. Additionally, the Langham ocular blood flow system was used to determine the ocular pulse amplitude (OPA) and the pulsatile ocular blood flow (pOBF). The measurements were correlated with systemic blood pressure (BP), ocular perfusion pressure (OPP), capillary base excess parameters and serum AZ levels. Arterial and venous VD were significantly increased by about 4-5% each. Papillary BF increased significantly about 40%. Parapapillary retinal flow dropped significantly about 19% (120 min). OPA and pOBF showed no statistically significant changes. BP showed no significant changes, and OPP was significantly increased. There were no correlations with pH or systemic perfusion parameters. AZ leads to a dilatation of retinal VD, to an increase of BF in the optic nerve head, and to a decrease of parapapillary retinal BF. The different BF changes in different vascular beds might be due to different regulatory mechanisms, steal effects, or different distributions of the carbonic anhydrase.

Long-term consequences of developmental vascular defects on retinal vessel homeostasis and function in a mouse model of Norrie disease.

PubMed

Beck, Susanne C; Feng, Yuxi; Sothilingam, Vithiyanjali; Garcia Garrido, Marina; Tanimoto, Naoyuki; Acar, Niyazi; Shan, Shenliang; Seebauer, Britta; Berger, Wolfgang; Hammes, Hans-Peter; Seeliger, Mathias W

2017-01-01

Loss of Norrin signalling due to mutations in the Norrie disease pseudoglioma gene causes severe vascular defects in the retina, leading to visual impairment and ultimately blindness. While the emphasis of experimental work so far was on the developmental period, we focus here on disease mechanisms that induce progression into severe adult disease. The goal of this study was the comprehensive analysis of the long-term effects of the absence of Norrin on vascular homeostasis and retinal function. In a mouse model of Norrie disease retinal vascular morphology and integrity were studied by means of in vivo angiography; the vascular constituents were assessed in detailed histological analyses using quantitative retinal morphometry. Finally, electroretinographic analyses were performed to assess the retinal function in adult Norrin deficient animals. We could show that the primary developmental defects not only persisted but developed into further vascular abnormalities and microangiopathies. In particular, the overall vessel homeostasis, the vascular integrity, and also the cellular constituents of the vascular wall were affected in the adult Norrin deficient retina. Moreover, functional analyses indicated to persistent hypoxia in the neural retina which was suggested as one of the major driving forces of disease progression. In summary, our data provide evidence that the key to adult Norrie disease are ongoing vascular modifications, driven by the persistent hypoxic conditions, which are ineffective to compensate for the primary Norrin-dependent defects.

Visual cycle modulation in neurovascular retinopathy.

PubMed

Akula, James D; Hansen, Ronald M; Tzekov, Radouil; Favazza, Tara L; Vyhovsky, Tanya C; Benador, Ilan Y; Mocko, Julie A; McGee, David; Kubota, Ryo; Fulton, Anne B

2010-08-01

Rats with oxygen-induced retinopathy (OIR) model the pediatric retinal disease retinopathy of prematurity (ROP). Recent findings in OIR rats imply a causal role for the rods in the ROP disease process, although only experimental manipulation of rod function can establish this role conclusively. Accordingly, a visual cycle modulator (VCM) - with no known direct effect on retinal vasculature - was administered to "50/10 model" OIR Sprague-Dawley rats to test the hypotheses that it would 1) alter rod function and 2) consequently alter vascular outcome. Four litters of pups (N=46) were studied. For two weeks, beginning on postnatal day (P) 7, the first and fourth litters were administered 6 mg kg(-1) N-retinylacetamide (the VCM) intraperitoneally; the second and third litters received vehicle (DMSO) alone. Following a longitudinal design, retinal function was assessed by electroretinography (ERG) and the status of the retinal vessels was monitored using computerized fundus photograph analysis. Rod photoreceptor and post-receptor response amplitudes were significantly higher in VCM-treated than in vehicle-treated rats; deactivation of phototransduction was also significantly more rapid. Notably, the arterioles of VCM-treated rats showed significantly greater recovery from OIR. Presuming that the VCM did not directly affect the retinal vessels, a causal role for the neural retina - particularly the rod photoreceptors - in OIR was confirmed. There was no evidence of negative alteration of photoreceptor function consequent to VCM treatment. This finding implicates the rods as a possible therapeutic target in neurovascular diseases such as ROP. Copyright 2010 Elsevier Ltd. All rights reserved.

LPS-induced microvascular leukocytosis can be assessed by blue-field entoptic phenomenon.

PubMed

Kolodjaschna, Julia; Berisha, Fatmire; Lung, Solveig; Schaller, Georg; Polska, Elzbieta; Jilma, Bernd; Wolzt, Michael; Schmetterer, Leopold

2004-08-01

Administration of low doses of Escherichia coli endotoxin [a lipopolysaccharide (LPS)] to humans enables the study of inflammatory mechanisms. The purpose of the present study was to investigate whether the blue-field entoptic technique may be used to quantify the increase in circulating leukocytes in the ocular microvasculature after LPS infusion. In addition, combined laser Doppler velocimetry and retinal vessel size measurement were used to study red blood cell movement. Twelve healthy male volunteers received 20 IU/kg iv LPS as a bolus infusion. Outcome parameters were measured at baseline and 4 h after LPS administration. In the first protocol (n = 6 subjects), ocular hemodynamic effects were assessed with the blue-field entoptic technique, the retinal vessel analyzer, and laser Doppler velocimetry. In the second protocol (n = 6 subjects), white blood cell (WBC) counts from peripheral blood samples and blue-field entoptic technique measurements were performed. LPS caused peripheral blood leukocytosis and increased WBC density in ocular microvessels (by 49%; P = 0.036) but did not change WBC velocity. In addition, retinal venous diameter was increased (by 9%; P = 0.008), but red blood cell velocity remained unchanged. The LPS-induced changes in retinal WBC density and leukocyte counts were significantly correlated (r = 0.87). The present study indicates that the blue-field entoptic technique can be used to assess microvascular leukocyte recruitment in vivo. In addition, our data indicate retinal venous dilation in response to endotoxin.

Retinal expression of Wnt-pathway mediated genes in low-density lipoprotein receptor-related protein 5 (Lrp5) knockout mice.

PubMed

Chen, Jing; Stahl, Andreas; Krah, Nathan M; Seaward, Molly R; Joyal, Jean-Sebastian; Juan, Aimee M; Hatton, Colman J; Aderman, Christopher M; Dennison, Roberta J; Willett, Keirnan L; Sapieha, Przemyslaw; Smith, Lois E H

2012-01-01

Mutations in low-density lipoprotein receptor-related protein 5 (Lrp5) impair retinal angiogenesis in patients with familial exudative vitreoretinopathy (FEVR), a rare type of blinding vascular eye disease. The defective retinal vasculature phenotype in human FEVR patients is recapitulated in Lrp5 knockout (Lrp5(-/-)) mouse with delayed and incomplete development of retinal vessels. In this study we examined gene expression changes in the developing Lrp5(-/-) mouse retina to gain insight into the molecular mechanisms that underlie the pathology of FEVR in humans. Gene expression levels were assessed with an Illumina microarray on total RNA from Lrp5(-/-) and WT retinas isolated on postnatal day (P) 8. Regulated genes were confirmed using RT-qPCR analysis. Consistent with a role in vascular development, we identified expression changes in genes involved in cell-cell adhesion, blood vessel morphogenesis and membrane transport in Lrp5(-/-) retina compared to WT retina. In particular, tight junction protein claudin5 and amino acid transporter slc38a5 are both highly down-regulated in Lrp5(-/-) retina. Similarly, several Wnt ligands including Wnt7b show decreased expression levels. Plasmalemma vesicle associated protein (plvap), an endothelial permeability marker, in contrast, is up-regulated consistent with increased permeability in Lrp5(-/-) retinas. Together these data suggest that Lrp5 regulates multiple groups of genes that influence retinal angiogenesis and may contribute to the pathogenesis of FEVR.

Retinal Photoreceptors and Microvascular Changes in Prediabetes Measured with Adaptive Optics (rtx1™): A Case-Control Study.

PubMed

Zaleska-Żmijewska, Anna; Piątkiewicz, Paweł; Śmigielska, Barbara; Sokołowska-Oracz, Anna; Wawrzyniak, Zbigniew M; Romaniuk, Dorota; Szaflik, Jerzy; Szaflik, Jacek P

2017-01-01

Patients with prediabetes are at risk for diabetes, cardiovascular events, and microvascular complications. The rtx1 (Imagine Eyes, France) permits early detection of changes in the retinal photoreceptors and vessels. Cone parameters and retinal microvasculature were analyzed with the rtx1 in 12 prediabetic patients and 22 healthy subjects. The analysis was based on cone density (DM), interphotoreceptor distance (SM), cone packing regularity, and retinal vessel parameters: wall thickness, lumen diameter (LD), wall-to-lumen ratio (WLR), and cross-sectional area of the vascular wall. DM in the prediabetic group was not significantly lower than that in the control group (18,935 ± 1713 cells/mm 2 and 19,900 ± 2375 cells/mm 2 , respectively; p = 0.0928). The LD and WLR means differed significantly between the prediabetic and the control groups (LD 94.3 ± 10.9 versus 101.2 ± 15, p = 0.022; WLR 0.29 ± 0.05 versus 0.22 ± 0.03, p < 0.05). A multivariate regression analysis showed that the WLR was significantly correlated with BMI and total cholesterol. Abnormalities found in rtx1 examinations indicated early signs of arteriolar dysfunction, prior to impaired glucose tolerance progressing to diabetes. The rtx1 retinal image analysis offers noninvasive measurement of early changes in the vasculature that routine clinical examination cannot detect.

Long-term consequences of developmental vascular defects on retinal vessel homeostasis and function in a mouse model of Norrie disease

PubMed Central

Sothilingam, Vithiyanjali; Garcia Garrido, Marina; Tanimoto, Naoyuki; Acar, Niyazi; Shan, Shenliang; Seebauer, Britta; Berger, Wolfgang; Hammes, Hans-Peter; Seeliger, Mathias W.

2017-01-01

Loss of Norrin signalling due to mutations in the Norrie disease pseudoglioma gene causes severe vascular defects in the retina, leading to visual impairment and ultimately blindness. While the emphasis of experimental work so far was on the developmental period, we focus here on disease mechanisms that induce progression into severe adult disease. The goal of this study was the comprehensive analysis of the long-term effects of the absence of Norrin on vascular homeostasis and retinal function. In a mouse model of Norrie disease retinal vascular morphology and integrity were studied by means of in vivo angiography; the vascular constituents were assessed in detailed histological analyses using quantitative retinal morphometry. Finally, electroretinographic analyses were performed to assess the retinal function in adult Norrin deficient animals. We could show that the primary developmental defects not only persisted but developed into further vascular abnormalities and microangiopathies. In particular, the overall vessel homeostasis, the vascular integrity, and also the cellular constituents of the vascular wall were affected in the adult Norrin deficient retina. Moreover, functional analyses indicated to persistent hypoxia in the neural retina which was suggested as one of the major driving forces of disease progression. In summary, our data provide evidence that the key to adult Norrie disease are ongoing vascular modifications, driven by the persistent hypoxic conditions, which are ineffective to compensate for the primary Norrin-dependent defects. PMID:28575130

Spectral-Domain Optical Coherence Tomographic Angiography in Children With Amblyopia.

PubMed

Lonngi, Marcela; Velez, Federico G; Tsui, Irena; Davila, Juan Pablo; Rahimi, Mansour; Chan, Clarissa; Sarraf, David; Demer, Joseph L; Pineles, Stacy L

2017-10-01

Amblyopia is the most common cause of visual impairment in childhood, with a prevalence of 1% to 4% in children in the United States. To date, no studies using noninvasive optical coherence tomographic angiography (OCTA) have measured blood flow in the retinal capillary layers in children with amblyopia. To evaluate the retinal and microvascular features using OCTA in children (<18 years) with amblyopia. This observational case-control study enrolled patients from September 1, 2016, through May 31, 2017, and was conducted from September 1, 2016, through June 30, 2017, at the Stein Eye Institute at UCLA (University of California, Los Angeles). Participants included 59 children (<18 years) with amblyopia and without amblyopia examined at a pediatric ophthalmology clinic or referred to the clinic by coinvestigators. All patients underwent comprehensive ophthalmological examination, including visual acuity, refraction, and ocular motility tests; anterior and posterior segment examination; and OCTA. Reduced superficial and deep retinal capillary vessel density on OCTA. Of the 63 eyes evaluated, 13 (21%) were amblyopic and 50 (79%) were control eyes. Of the 59 patients, the mean (SD) age of patients with amblyopia was 8.0 (4.0) years and 10.3 (3.3) years for the controls; 33 patients (56%) were female; and 5 of 13 (39%) and 27 of 46 (54%) patients in the amblyopic and control groups, respectively, were identified as white. The macular vessel density of the superficial capillary plexus was lower in the amblyopic group than in the control group in both 3 × 3-mm and 6 × 6-mm scans. After adjusting for age and refractive error, the mean (SD) difference in the superficial capillary plexus in the 6 × 6-mm scan was statistically significant (49.3% [4.1] vs 51.2% [2.9]; P = .02). Macular vessel density of the deep capillary plexus in the 6 × 6-mm scans was also considerably different between groups: mean (SD) vessel density of the deep retinal capillary plexus was 54.4% (4.7%) in the amblyopia group and 60.1% (3.3%) in the control group, with a difference of 5.7% (95% CI, 3.4%-8.1%; P = .002). The study found that OCTA reveals subnormal superficial and deep retinal capillary density in the macula of patients with amblyopia. Further studies are needed to determine the clinical relevance of this finding.

Exploration of peripapillary vessel density in highly myopic eyes with peripapillary intrachoroidal cavitation and its relationship with ocular parameters using optical coherence tomography angiography.

PubMed

Chen, Qiuying; He, Jiangnan; Hua, Yihong; Fan, Ying

2017-12-01

Identifying changes of peripapillary vessel density in highly myopic eyes with peripapillary intrachoroidal cavitation by optical coherence tomography angiography. To investigate peripapillary vessel density and its relationship with other ocular parameters in highly myopic eyes with peripapillary intrachoroidal cavitation. Hospital-based, cross-sectional study. Thirty-five highly myopic eyes with peripapillary intrachoroidal cavitation, 46 highly myopic eyes without peripapillary intrachoroidal cavitation and 36 normal eyes were included in this study. All participants underwent optical coherence tomography angiography to image the retinal vasculature in the peripapillary areas, including the radial peripapillary capillaries and optic nerve head layer. Correlations between vessel density and ocular metrics were analysed. Peripapillary vessel density. In highly myopic eyes, vessel density was significantly lower in eyes with peripapillary intrachoroidal cavitation than in those without in peripapillary (P = 0.014, P = 0.037), inferotemporal (P < 0.001, P < 0.001) and superotemporal (P = 0.014, P = 0.009) areas. In the radial peripapillary capillaries layer, vessel density was negatively correlated with peripapillary atrophy area (P = 0.012) and myopic maculopathy (P = 0.002), and in the optic nerve head layer, it was negatively associated with a diagnosis of peripapillary intrachoroidal cavitation (P = 0.012) and myopic maculopathy (P < 0.001). In addition, it was positively correlated with retinal nerve fibre layer thickness in both layers (P < 0.001). Highly myopic eyes with peripapillary intrachoroidal cavitation had lower peripapillary vessel densities, especially in the temporal area, than those without. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

Automatic segmentation of pigment deposits in retinal fundus images of Retinitis Pigmentosa.

PubMed

Brancati, Nadia; Frucci, Maria; Gragnaniello, Diego; Riccio, Daniel; Di Iorio, Valentina; Di Perna, Luigi

2018-06-01

Retinitis Pigmentosa is an eye disease that presents with a slow loss of vision and then evolves until blindness results. The automatic detection of the early signs of retinitis pigmentosa acts as a great support to ophthalmologists in the diagnosis and monitoring of the disease in order to slow down the degenerative process. A large body of literature is devoted to the analysis of Retinitis Pigmentosa. However, all the existing approaches work on Optical Coherence Tomography (OCT) data, while hardly any attempts have been made working on fundus images. Fundus image analysis is a suitable tool in daily practice for an early detection of retinal diseases and the monitoring of their progression. Moreover, the fundus camera represents a low-cost and easy-access diagnostic system, which can be employed in resource-limited regions and countries. The fundus images of a patient suffering from retinitis pigmentosa are characterized by an attenuation of the vessels, a waxy disc pallor and the presence of pigment deposits. Considering that several methods have been proposed for the analysis of retinal vessels and the optic disk, this work focuses on the automatic segmentation of the pigment deposits in the fundus images. The image distortions are attenuated by applying a local pre-processing. Next, a watershed transformation is carried out to produce homogeneous regions. Working on regions rather than on pixels makes the method very robust to the high variability of pigment deposits in terms of color and shape, so allowing the detection even of small pigment deposits. The regions undergo a feature extraction procedure, so that a region classification process is performed by means of an outlier detection analysis and a rule set. The experiments have been performed on a dataset of images of patients suffering from retinitis pigmentosa. Although the images present a high variability in terms of color and illumination, the method provides a good performance in terms of sensitivity, specificity, accuracy and the F-measure, whose values are 74.43, 98.44, 97.90, 59.04, respectively. Copyright © 2018 Elsevier Ltd. All rights reserved.

Impaired retinal microcirculation in patients with Alzheimer’s disease

PubMed Central

Liu, Yi; Wei, Yantao; Shi, Yingying; Wright, Clinton B.; Sun, Xiaoyan; Rundek, Tatjana; Baumel, Bernard S.; Landman, Jonathan; Wang, Jianhua

2018-01-01

The goal of this study was to determine the retinal blood flow rate (BFR) and blood flow velocity (BFV) of pre-capillary arterioles and post-capillary venules in patients with mild cognitive impairment (MCI) and Alzheimer’s disease (AD). Forty patients (20 AD and 20 MCI) and 21 cognitively normal (CN) controls with a similar age range (± 5 yrs) were recruited. A retinal function imager (RFI) was used to measure BFRs and BFVs of arterioles and venules in the macular region. The thickness of the ganglion cell-inner plexiform layer (GCIPL) was measured using Zeiss Cirrus optical coherence tomography. Macular BFRs in AD group were 2.64 ± 0.20 nl/s (mean ± standard deviation) in arterioles and 2.23 ± 0.19 nl/s in venules, which were significantly lower than in MCI and CN groups (P < 0.05). In addition, BFRs in MCI were lower than in CN in both arterioles and venules (P < 0.05). The BFV of the arterioles was 3.20 ± 1.07 mm/s in AD patients, which was significantly lower than in CN controls (3.91 ± 0.77 mm/s, P = 0.01). The thicknesses of GCIPL in patients with AD and MCI were significantly lower than in CN controls (P < 0.05). Neither BFV nor BFR in arterioles and venules was related to age, GCIPL thickness, mini mental state examination (MMSE) score and disease duration in patients with AD and MCI (P > 0.05). The lower BFR in both arterioles and venules in AD and MCI patients together with the loss of GCIPL were evident, indicating the impairment of the two components in the neurovascular-hemodynamic system, which may play a role in disease progression. PMID:29394263

Swept Source OCT Angiography of Neovascular Macular Telangiectasia Type 2

PubMed Central

Zhang, Qinqin; Wang, Ruikang K.; Chen, Chieh-Li; Legarreta, Andrew D.; Durbin, Mary K.; An, Lin; Sharma, Utkarsh; Stetson, Paul F.; Legarreta, John E.; Roisman, Luiz; Gregori, Giovanni; Rosenfeld, Philip J.

2015-01-01

Objective To image subretinal neovascularization in proliferative macular telangiectasia type 2 (MacTel2) using swept source optical coherence tomography based microangiography (OMAG). Study Design Patients with MacTel2 were enrolled in a prospective, observational study known as the MacTel Project and evaluated using a high-speed 1050nm swept-source OCT (SS-OCT) prototype system. The OMAG algorithm generated en face flow images from three retinal layers, as well as the region bounded by the outer retina and Bruch’s membrane, the choriocapillaris, and the remaining choroidal vasculature. The en face OMAG images were compared to images from fluorescein angiography (FA) and indocyanine green angiography (ICGA). Results Three eyes with neovascular MacTel2 were imaged. The neovascularization was best identified from the en face OMAG images that included a layer between the outer retinal boundary and Bruch’s membrane. OMAG images identified these abnormal vessels better than FA and were comparable to the images obtained using ICGA. In all three cases, OMAG identified choroidal vessels communicating with the neovascularization, and these choroidal vessels were evident in the two cases with ICGA imaging. In one case, monthly injections of bevacizumab reduced the microvascular complexity of the neovascularization, as well as the telangiectatic changes within the retinal microvasculature. In another case, less frequent bevacizumab therapy was associated with growth of the subretinal neovascular complex. Conclusions OMAG imaging provided detailed, depth-resolved information about subretinal neovascularization in MacTel2 eyes demonstrating superiority to FA imaging and similarities to ICGA imaging for documenting the retinal microvascular changes, the size and extent of the neovascular complex, the communications between the neovascular complex and the choroidal circulation, and the response to monthly bevacizumab therapy. PMID:26457402

Selective Stimulation of Penumbral Cones Reveals Perception in the Shadow of Retinal Blood Vessels

PubMed Central

Spitschan, Manuel; Aguirre, Geoffrey K.; Brainard, David H.

2015-01-01

In 1819, Johann Purkinje described how a moving light source that displaces the shadow of the retinal blood vessels to adjacent cones can produce the entopic percept of a branching tree. Here, we describe a novel method for producing a similar percept. We used a device that mixes 56 narrowband primaries under computer control, in conjunction with the method of silent substitution, to present observers with a spectral modulation that selectively targeted penumbral cones in the shadow of the retinal blood vessels. Such a modulation elicits a clear Purkinje-tree percept. We show that the percept is specific to penumbral L and M cone stimulation and is not produced by selective penumbral S cone stimulation. The Purkinje-tree percept was strongest at 16 Hz and fell off at lower (8 Hz) and higher (32 Hz) temporal frequencies. Selective stimulation of open-field cones that are not in shadow, with penumbral cones silenced, also produced the percept, but it was not seen when penumbral and open-field cones were modulated together. This indicates the need for spatial contrast between penumbral and open-field cones to create the Purkinje-tree percept. Our observation provides a new means for studying the response of retinally stabilized images and demonstrates that penumbral cones can support spatial vision. Further, the result illustrates a way in which silent substitution techniques can fail to be silent. We show that inadvertent penumbral cone stimulation can accompany melanopsin-directed modulations that are designed only to silence open-field cones. This in turn can result in visual responses that might be mistaken as melanopsin-driven. PMID:25897842

Characteristics of eyes with inner retinal cleavage.

PubMed

Hwang, Young Hoon; Kim, Yong Yeon; Kim, Hwang Ki; Sohn, Yong Ho

2015-02-01

Inner retinal cleavage can be misdiagnosed as a glaucomatous retinal nerve fiber layer (RNFL) defect. This study was performed to characterize eyes with inner retinal cleavage. Inner retinal cleavage is defined as the appearance of a dark spindle-shaped space between the nerve fibers. Patients who presented at our institution with inner retinal cleavage were enrolled in the study. All participants were evaluated by fundus examination, visual field testing with standard automated perimetry, and optical coherence tomography (OCT) imaging. A total of 15 eyes of 11 subjects with inner retinal cleavage were included in the study. The median age of the subjects was 57 years (age range, 30-67 years). In each case, inner retinal cleavage was located adjacent to retinal blood vessels. Tissue bridging the cleavage area was observed in ten eyes. Six eyes had epiretinal membranes (ERMs), two eyes had glaucoma, and one eye had ERM in addition to glaucoma. Six eyes with inner retinal cleavage without combined ocular abnormalities had highly myopic refractive error (-6.50 to -8.50 diopters). Cross-sectional OCT images of the areas of inner retinal cleavage demonstrated defects with irregular margins and empty spaces in the inner layers of the retina. During the follow-up period, no eye showed changes in inner retinal layer cleavage or visual field sensitivity. Inner retinal cleavage was found in eyes with high myopia or ERMs. Inner retinal cleavage was associated with structural changes distinct from those associated with glaucomatous RNFL defects.

A novel method for retinal optic disc detection using bat meta-heuristic algorithm.

PubMed

Abdullah, Ahmad S; Özok, Yasa Ekşioğlu; Rahebi, Javad

2018-05-09

Normally, the optic disc detection of retinal images is useful during the treatment of glaucoma and diabetic retinopathy. In this paper, the novel preprocessing of a retinal image with a bat algorithm (BA) optimization is proposed to detect the optic disc of the retinal image. As the optic disk is a bright area and the vessels that emerge from it are dark, these facts lead to the selected segments being regions with a great diversity of intensity, which does not usually happen in pathological regions. First, in the preprocessing stage, the image is fully converted into a gray image using a gray scale conversion, and then morphological operations are implemented in order to remove dark elements such as blood vessels, from the images. In the next stage, a bat algorithm (BA) is used to find the optimum threshold value for the optic disc location. In order to improve the accuracy and to obtain the best result for the segmented optic disc, the ellipse fitting approach was used in the last stage to enhance and smooth the segmented optic disc boundary region. The ellipse fitting is carried out using the least square distance approach. The efficiency of the proposed method was tested on six publicly available datasets, MESSIDOR, DRIVE, DIARETDB1, DIARETDB0, STARE, and DRIONS-DB. The optic disc segmentation average overlaps and accuracy was in the range of 78.5-88.2% and 96.6-99.91% in these six databases. The optic disk of the retinal images was segmented in less than 2.1 s per image. The use of the proposed method improved the optic disc segmentation results for healthy and pathological retinal images in a low computation time. Graphical abstract ᅟ.

Displacement of the retina and its recovery after vitrectomy in idiopathic epiretinal membrane.

PubMed

Nitta, Eri; Shiraga, Fumio; Shiragami, Chieko; Fukuda, Kouki; Yamashita, Ayana; Fujiwara, Atsushi

2013-06-01

To study the displacement of the retina and its change after vitrectomy in idiopathic epiretinal membrane (ERM). Prospective, interventional case series. Fifty-six eyes of 53 consecutive patients with ERM underwent vitrectomy with ERM removal and internal limiting membrane peeling. Fundus autofluorescence (FAF) imaging was examined before and at 1, 3, 6, and 12 months after vitrectomy. Main outcome measures were the proportion of eyes with retinal displacement for ERM detected by FAF imaging and the recovery rate of retinal displacement after vitrectomy. Before surgery, FAF photography demonstrated hyperautofluorescent lines within the vascular arcade in 37 (66.1%) of the 56 eyes. The lines seemed to be consistent with the location of the retinal vessels before their displacement. These hyperautofluorescent lines appeared significantly more frequently among patients in whom the disease duration was 3 years or less. In 23 (62.2%) of these 37 eyes, within the first postoperative month, the hyperautofluorescent lines disappeared. The disappearance of the hyperautofluorescent line was thought to be the result of the return of the retinal vessel to its original position. Greater visual improvements (logarithm of the minimal angle of resolution, ≥0.3) were statistically significantly obtained in patients in whom the hyperautofluorescent lines had become indistinct at 1 month after surgery (P < .05). Hyperautofluorescent lines indicating retinal displacement were found by FAF in 66.1% of patients before surgery for ERM. In addition, retinal displacement was significantly more common among patients who had experienced subjective symptoms for 3 years or less. Fundus autofluorescence is useful for predicting postoperative visual acuity improvement. Copyright © 2013 Elsevier Inc. All rights reserved.

Epidemiology and clinical features of inflammatory retinal vascular occlusions: pooled data from two tertiary-referral institutions.

PubMed

Agarwal, Aniruddha; Karkhur, Samendra; Aggarwal, Kanika; Invernizzi, Alessandro; Singh, Ramandeep; Dogra, Mangat R; Gupta, Vishali; Gupta, Amod; Do, Diana V; Nguyen, Quan D

2018-01-01

In a subset of patients with retinal vasculitis, there is occlusion of blood flow through the retinal vessels. These eyes are at high risk of sight-threatening complications. To characterize epidemiology, clinical course, treatment and outcomes of occlusive retinal vasculitis (ORV). Retrospective study PARTICIPANTS: Seventy-seven uveitis patients with ORV at two large tertiary-care institutions (the USA and India). Out of 2438 patients screened, 346 patients were diagnosed with retinal vasculitis of which 77 patients (96 eyes) were diagnosed with ORV. Patients with ORV (capillary, arteriolar and/or venular) were further analysed. Diagnostic criteria for occlusive vasculitis included (i) absence of blood flow in vessels (arterioles, venules and/or capillaries), (ii) capillary non-perfusion areas and/or arteriolar-venous anastomosis and (iii) intraretinal haemorrhages, cotton-wool spots or vitreous haemorrhage. Best-corrected visual acuity, treatment and complications. The mean age was 32.09 ± 13.51 years. Most common aetiologies were tuberculosis and Adamantiades-Behçet's disease in India and systemic lupus erythematosus in the USA. Best-corrected visual acuity improved from 0.38 ± 0.30 logMAR (20/48 Snellen equivalent) (baseline) to 0.25 ± 0.30 (20/35 Snellen equivalent) at final visit (P < 0.0001). Vitreous haemorrhage was seen in 31.08% eyes. Pars plana vitrectomy was performed in 12.16% eyes. Therapy with systemic steroids was required in 78.48% patients. In addition, 46.75% patients required immunomodulators and/or biologics. Occlusive retinal vasculitis is caused by heterogeneous group of uveitides depending upon the geographic location. It is imperative to identify eyes with ORV as they are predisposed to complications requiring aggressive therapy. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

[Static Retinal Vessel Analysis in Population-based Study SHIP-Trend].

PubMed

Theophil, Constanze; Jürgens, Clemens; Großjohann, Rico; Kempin, Robert; Ittermann, Till; Nauck, Matthias; Völzke, Henry; Tost, Frank H W

2017-08-24

Background Interdisciplinary investigations of possible connections between general diseases and ophthalmological changes are difficult to perform in the clinical environment. But they are gaining in importance as a result of the age-related increase in chronic diseases. The collection of health-related parameters in the Study of Health in Pomerania (SHIP) project allows to derive conclusions for the general population. Methods The population-based SHIP trend study was conducted between 2008 and 2012 in Greifswald. The baseline cohort included 4420 subjects (response 50.1%) at the age of 20 to 84 years. The pre-existence of arterial hypertension, diabetes mellitus and smoking status were questioned in a standardized questionnaire, the blood pressure and the HbA 1c were determined by the laboratory. The vascular diameter of retinal arterioles and venules were determined by means of non-mydriatic fundus images and the retinal arterial (CRAE) and venous equivalent (CRVE) were calculated therefrom. The association of diabetes mellitus, HbA 1c , smoking status and blood pressure with the retinal vascular parameters was tested for age and sex with linear regression models. Results In 3218 subjects with evaluable standardized fundus photographs, significant associations of elevated HbA 1c (> 6.5%), smoking status and systolic and diastolic blood pressure were found with the retinal vessel widths CRAE and CRVE. Anamnestic diabetes mellitus, on the other hand, was not associated with any of the vascular parameters. Conclusion This research study reveals a relevant correlation between general diseases and the retinal blood flow in the eye. Therefore, general diseases can induce ophthalmological changes and eye examination can provide information for the assessment of general diseases. Georg Thieme Verlag KG Stuttgart · New York.

From microscopic to astronomic, the legacy of Carl Zeiss.

PubMed

Louw, Deon F; Sutherland, Garnette R; Schulder, Michael

2003-03-01

IN 1846, CARL ZEISS established a workshop to make lenses for microscopes, cameras, binoculars, and astronomical observatories. He was a master craftsman and was intolerant of any flaw, destroying microscopes with only minor inaccuracies. His relentless pursuit of perfection brought him into contact with a brilliant physicist, Ernst Abbe. Zeiss combined Abbe's new optical laws with his own technical skills; together, they created a colossus. Their company came to be known not only for exquisite technical standards but also for labor relations that were and remain progressive. The development of microneurosurgery was aided by the active participation of Carl Zeiss, Inc. The history of this company provides a lesson in the power of entrepreneurship and the benefits to humanity that can accrue from a fruitful partnership between medical science and industry.

The Protective Effects of Lycium Barbarum Polysaccharides on Transient Retinal Ischemia

PubMed Central

Yang, Di; Li, Suk-Yee; Yeung, Chung-Man; Yu, Wing-Yan; Chang, Raymond Chuen-Chung; So, Kwok-Fai; Wong, David; Lo, Amy C. Y.

2011-01-01

Retinal ischemia/reperfusion (I/R) injury leads to irreversible neuronal death, glial activation, retinal swelling and oxidative stress. It is a common feature in various ocular diseases, such as glaucoma, diabetic retinopathy and amaurosis fugax. In the present study, we aimed to evaluate the effects of Lycium Barbarum Polysaccharides (LBP) in a murine retinal I/R model. Mice were orally treated with either vehicle (PBS) or LBP (1mg/kg) daily for 1 week before induction of retinal ischemia. Retinae were collected after 2 hours ischemia and 22 hours reperfusion. Paraffin-embedded sections were prepared for immunohistochemical analyses. Significantly fewer viable cells were found in vehicle-treated retinae comparing to LBP group. This finding was further confirmed by TUNEL assay where significantly fewer apoptotic cells were identified in LBP-treated retinae. Additionally, retinal swelling induced by retinal I/R injury in the vehicle-treated group was not observed in LBP-treated group. Moreover, intense GFAP immunoreactivity and IgG extravasation were observed in vehicle-treated group but not in LBP treated group. The results showed that pre-treatment with LBP was protective in retinal I/R injury via reducing neuronal death, apoptosis, retinal swelling, GFAP activation and blood vessel leakage. LBP may be used as a preventive agent for retinal ischemia diseases.

[Retinal vasculitis and systemic diseases].

PubMed

Gascon, P; Jarrot, P-A; Matonti, F; Kaplanski, G

2018-06-19

Retinal vasculitis (RV) is an inflammation of retinal blood vessels that can be associated with uveitis or be isolated, and can induce vascular occlusion and retinal ischemia. Visual acuity can be severely affected in case of macular involvement or neovessel formation. The diagnosis relies on fundoscopy and fluorescein angiography. Systemic diseases may be associated with RV, the most frequently encountered are Behçet's disease, sarcoidosis or multiple sclerosis, all predominantly associated with venous involvement, whereas systemic lupus erythematosus and necrotizing vasculitis are less frequently observed and predominantly associated with arterial or mixed vasculitis. Treatments are usually aggressive in order to preserve a good visual acuity and to reduce retinal inflammation and chronic ischemia. Steroids, immunosuppressive drugs, retinal laser photocoagulation, intravitreal anti-VEGF injections are usual treatments and more recently, anti-TNFalpha monoclonal therapeutic antibodies have been shown to be very successful. Copyright © 2018 Société Nationale Française de Médecine Interne (SNFMI). Published by Elsevier Masson SAS. All rights reserved.

Retinal blood vessel segmentation in high resolution fundus photographs using automated feature parameter estimation

NASA Astrophysics Data System (ADS)

Orlando, José Ignacio; Fracchia, Marcos; del Río, Valeria; del Fresno, Mariana

2017-11-01

Several ophthalmological and systemic diseases are manifested through pathological changes in the properties and the distribution of the retinal blood vessels. The characterization of such alterations requires the segmentation of the vasculature, which is a tedious and time-consuming task that is infeasible to be performed manually. Numerous attempts have been made to propose automated methods for segmenting the retinal vasculature from fundus photographs, although their application in real clinical scenarios is usually limited by their ability to deal with images taken at different resolutions. This is likely due to the large number of parameters that have to be properly calibrated according to each image scale. In this paper we propose to apply a novel strategy for automated feature parameter estimation, combined with a vessel segmentation method based on fully connected conditional random fields. The estimation model is learned by linear regression from structural properties of the images and known optimal configurations, that were previously obtained for low resolution data sets. Our experiments in high resolution images show that this approach is able to estimate appropriate configurations that are suitable for performing the segmentation task without requiring to re-engineer parameters. Furthermore, our combined approach reported state of the art performance on the benchmark data set HRF, as measured in terms of the F1-score and the Matthews correlation coefficient.

A Multi-Anatomical Retinal Structure Segmentation System for Automatic Eye Screening Using Morphological Adaptive Fuzzy Thresholding

PubMed Central

Elleithy, Khaled; Elleithy, Abdelrahman

2018-01-01

Eye exam can be as efficacious as physical one in determining health concerns. Retina screening can be the very first clue for detecting a variety of hidden health issues including pre-diabetes and diabetes. Through the process of clinical diagnosis and prognosis; ophthalmologists rely heavily on the binary segmented version of retina fundus image; where the accuracy of segmented vessels, optic disc, and abnormal lesions extremely affects the diagnosis accuracy which in turn affect the subsequent clinical treatment steps. This paper proposes an automated retinal fundus image segmentation system composed of three segmentation subsystems follow same core segmentation algorithm. Despite of broad difference in features and characteristics; retinal vessels, optic disc, and exudate lesions are extracted by each subsystem without the need for texture analysis or synthesis. For sake of compact diagnosis and complete clinical insight, our proposed system can detect these anatomical structures in one session with high accuracy even in pathological retina images. The proposed system uses a robust hybrid segmentation algorithm combines adaptive fuzzy thresholding and mathematical morphology. The proposed system is validated using four benchmark datasets: DRIVE and STARE (vessels), DRISHTI-GS (optic disc), and DIARETDB1 (exudates lesions). Competitive segmentation performance is achieved, outperforming a variety of up-to-date systems and demonstrating the capacity to deal with other heterogeneous anatomical structures. PMID:29888146

ROCK-1 mediates diabetes-induced retinal pigment epithelial and endothelial cell blebbing: Contribution to diabetic retinopathy.

PubMed

Rothschild, Pierre-Raphaël; Salah, Sawsen; Berdugo, Marianne; Gélizé, Emmanuelle; Delaunay, Kimberley; Naud, Marie-Christine; Klein, Christophe; Moulin, Alexandre; Savoldelli, Michèle; Bergin, Ciara; Jeanny, Jean-Claude; Jonet, Laurent; Arsenijevic, Yvan; Behar-Cohen, Francine; Crisanti, Patricia

2017-08-18

In diabetic retinopathy, the exact mechanisms leading to retinal capillary closure and to retinal barriers breakdown remain imperfectly understood. Rho-associated kinase (ROCK), an effector of the small GTPase Rho, involved in cytoskeleton dynamic regulation and cell polarity is activated by hyperglycemia. In one year-old Goto Kakizaki (GK) type 2 diabetic rats retina, ROCK-1 activation was assessed by its cellular distribution and by phosphorylation of its substrates, MYPT1 and MLC. In both GK rat and in human type 2 diabetic retinas, ROCK-1 is activated and associated with non-apoptotic membrane blebbing in retinal vessels and in retinal pigment epithelium (RPE) that respectively form the inner and the outer barriers. Activation of ROCK-1 induces focal vascular constrictions, endoluminal blebbing and subsequent retinal hypoxia. In RPE cells, actin cytoskeleton remodeling and membrane blebs in RPE cells contributes to outer barrier breakdown. Intraocular injection of fasudil, significantly reduces both retinal hypoxia and RPE barrier breakdown. Diabetes-induced cell blebbing may contribute to ischemic maculopathy and represent an intervention target.

Association of Retinopathy and Retinal Microvascular Abnormalities with Stroke and Cerebrovascular Disease

PubMed Central

Hughes, Alun D; Falaschetti, Emanuela; Witt, Nicholas; Wijetunge, Sumangali; Thom, Simon A McG; Tillin, Therese; Aldington, Steve J; Chaturvedi, Nish

2016-01-01

Background and purpose Abnormalities of the retinal circulation may be associated with cerebrovascular disease. We investigated associations between retinal microvascular abnormalities and 1) strokes and subclinical cerebral infarcts and 2) cerebral white matter lesions in a UK-based tri-ethnic population-based cohort. Methods 1185 participants (age 68.8±6.1y; 77% male) underwent retinal imaging and cerebral MRI. Cerebral infarcts and white matter hyperintensities (WMH) were identified on MRI, retinopathy was graded and retinal vessels were measured. Results Higher retinopathy grade (odds ratio (OR) = 1.40 (1.16, 1.70)), narrower arteriolar diameter (OR = 0.98 (0.97, 0.99)), fewer symmetrical arteriolar bifurcations (OR = 0.84 (0.75, 0.95)), higher arteriolar optimality deviation (OR = 1.16 (1.00, 1.34)) and more tortuous venules (OR = 1.20(1.09, 1.32)) were associated with strokes/infarcts and WMH. Associations with quantitative retinal microvascular measures were independent of retinopathy. Conclusions Abnormalities of the retinal microvasculature are independently associated with stroke, cerebral infarcts and white matter lesions. PMID:27729577

Portable dynamic fundus instrument

NASA Technical Reports Server (NTRS)

Taylor, Gerald R. (Inventor); Meehan, Richard T. (Inventor); Hunter, Norwood R. (Inventor); Caputo, Michael P. (Inventor); Gibson, C. Robert (Inventor)

1992-01-01

A portable diagnostic image analysis instrument is disclosed for retinal funduscopy in which an eye fundus image is optically processed by a lens system to a charge coupled device (CCD) which produces recordable and viewable output data and is simultaneously viewable on an electronic view finder. The fundus image is processed to develop a representation of the vessel or vessels from the output data.

Application of intraoperative indocyanine green angiography for CNS tumors: results on the first 100 cases.

PubMed

Ferroli, P; Acerbi, F; Albanese, E; Tringali, G; Broggi, M; Franzini, A; Broggi, G

2011-01-01

To investigate the application of indocyanine green (ICG) videoangiography during microsurgery for central nervous system (CNS) tumors. One hundred patients with CNS tumors who underwent microsurgical resection from December 2006 to December 2008 were retrospectively analyzed. The diagnosis was high grade glioma in 54 cases, low grade in 17 cases, meningioma in 14 cases, metastasis in 12 cases and hemangioblastoma in 3 cases. Overall, ICG was injected intraoperatively 194 times. The standard dose of 25mg of dye was injected intravenously and intravascular fluorescence from within the blood vessels was imaged through an ad hoc microscope with dedicated software (Pentero, Carl Zeiss Co., Oberkochen, Germany). Pre-resection and post-resection arterial, capillary and venous ICG videoangiographic phases were intraoperatively observed and recorded. ICG videangiography allowed for a good evaluation of blood flow in the tumoral and peritumoral exposed vessels in all cases. No side effects due to ICG were observed. ICG video-angiography is a significant method for monitoring blood flow in the exposed vessels during microsurgical removal of CNS tumors. Pre-resection videoangiography provides useful information on the tumoral circulation and the pathology-induced alteration in surrounding brain circulation. Post-resection examination allows for an immediate check of patency of those vessels that are closely related to the tumor mass and that the surgeon does not want to damage.

Deep neural ensemble for retinal vessel segmentation in fundus images towards achieving label-free angiography.

PubMed

Lahiri, A; Roy, Abhijit Guha; Sheet, Debdoot; Biswas, Prabir Kumar

2016-08-01

Automated segmentation of retinal blood vessels in label-free fundus images entails a pivotal role in computed aided diagnosis of ophthalmic pathologies, viz., diabetic retinopathy, hypertensive disorders and cardiovascular diseases. The challenge remains active in medical image analysis research due to varied distribution of blood vessels, which manifest variations in their dimensions of physical appearance against a noisy background. In this paper we formulate the segmentation challenge as a classification task. Specifically, we employ unsupervised hierarchical feature learning using ensemble of two level of sparsely trained denoised stacked autoencoder. First level training with bootstrap samples ensures decoupling and second level ensemble formed by different network architectures ensures architectural revision. We show that ensemble training of auto-encoders fosters diversity in learning dictionary of visual kernels for vessel segmentation. SoftMax classifier is used for fine tuning each member autoencoder and multiple strategies are explored for 2-level fusion of ensemble members. On DRIVE dataset, we achieve maximum average accuracy of 95.33% with an impressively low standard deviation of 0.003 and Kappa agreement coefficient of 0.708. Comparison with other major algorithms substantiates the high efficacy of our model.

Levels of retinal IAPP are altered in Alzheimer's disease patients and correlate with vascular changes and hippocampal IAPP levels.

PubMed

Schultz, Nina; Byman, Elin; Wennström, Malin

2018-06-01

Islet amyloid polypeptide (IAPP) forms toxic aggregates in the brain of patients with Alzheimer's disease (AD). Whether IAPP also affects the retina in these patients is still unknown. Levels of IAPP in soluble and insoluble homogenate fractions of retina and hippocampus from AD patients and nondemented controls were analyzed using ELISA. Number of pericytes and vessel length were determined by analysis of immunostained retina and hippocampus. Insoluble retinal fractions of AD patients contained lower levels of unmodified IAPP, whereas soluble retinal fractions contained increased levels of the same. Total IAPP levels and pericyte numbers in retina mirrored corresponding variables in the hippocampus. Moreover, levels of total unmodified IAPP correlated negatively with the vessel length both in retina and hippocampus across the group and positively with pericyte numbers in retina in AD patients. Our studies indicate that changes in brain IAPP are reflected by corresponding levels in the retina. Our results also suggest modification of IAPP as an important event implicated in vascular changes associated with AD. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Early Detection of Diabetic Retinopathy.

PubMed

Safi, Hamid; Safi, Sare; Hafezi-Moghadam, Ali; Ahmadieh, Hamid

2018-04-18

Diabetic retinopathy (DR) is a primary cause of visual impairment worldwide. Diabetes mellitus may be associated with ophthalmoscopically nonvisible neurovascular damage that progresses before the first clinical signs of DR appear. Reduction of the inner neuroretinal layer thickness on macular optical coherence tomography (OCT), reduced contrast sensitivity primarily at low spatial frequencies, abnormal results in color vision and microperimetry tests, and a prolonged implicit time recorded by multifocal electroretinography have been proposed for detection of early functional and nonvisible structural neuroretinal changes. Vascular abnormalities such as changes in the retinal vessels caliber, architectural indices, and blood flow have been investigated to evaluate the early stages of DR. The results of OCT angiography, retinal vessel oxygen saturation patterns, and elevated levels of circulating blood markers and cytokines have been suggested as early signs of DR. Light-based molecular imaging in rodents has been developed to demonstrate changes in protein expressions in the retinal microvessels as diagnostic biomarkers. Future clinical studies will examine the safety and efficacy of this approach in humans. We summarize all studies related to subclinical DR biomarkers. Copyright © 2018 Elsevier Inc. All rights reserved.

Oxygen saturation in optic nerve head structures by hyperspectral image analysis.

PubMed

Beach, James; Ning, Jinfeng; Khoobehi, Bahram

2007-02-01

A method is presented for the calculation and visualization of percent blood oxygen saturation from specific tissue structures in hyperspectral images of the optic nerve head (ONH). Trans-pupillary images of the primate optic nerve head and overlying retinal blood vessels were obtained with a hyperspectral imaging (HSI) system attached to a fundus camera. Images were recorded during normal blood flow and after partially interrupting flow to the ONH and retinal circulation by elevation of the intraocular pressure (IOP) from 10 mmHg to 55 mmHg in steps. Percent oxygen saturation was calculated from groups of pixels associated with separate tissue structures, using a linear least-squares curve fit of the recorded hemoglobin spectrum to reference spectra obtained from fully oxygenated and deoxygenated red cell suspensions. Color maps of saturation were obtained from a new algorithm that enables comparison of oxygen saturation from large vessels and tissue areas in hyperspectral images. Percent saturation in retinal vessels and from the average over ONH structures (IOP = 10 mmHg) was (mean +/- SE): artery 81.8 +/- 0.4%, vein 42.6 +/- 0.9%, average ONH 68.3 +/- 0.4%. Raising IOP from 10 mmHg to 55 mmHg for 5 min caused blood oxygen saturation to decrease (mean +/- SE): artery 46.1 +/- 6.2%, vein 36.1 +/- 1.6%, average ONH 41.9 +/- 1.6%. The temporal cup showed the highest saturation at low and high IOP (77.3 +/- 1.0% and 60.1 +/- 4.0%) and the least reduction in saturation at high IOP (22.3%) compared with that of the average ONH (38.6%). A linear relationship was found between saturation indices obtained from the algorithm and percent saturation values obtained by spectral curve fits to calibrated red cell samples. Percent oxygen saturation was determined from hyperspectral images of the ONH tissue and retinal vessels overlying the ONH at normal and elevated IOP. Pressure elevation was shown to reduce blood oxygen saturation in vessels and ONH structures, with the smallest reduction in the ONH observed in the temporal cup. IOP-induced saturation changes were visualized in color maps using an algorithm that follows saturation-dependent changes in the blood spectrum and blood volume differences across tissue. Reduced arterial saturation at high IOP may have resulted from a flow-dependent mechanism.

Automated detection of retinal whitening in malarial retinopathy

NASA Astrophysics Data System (ADS)

Joshi, V.; Agurto, C.; Barriga, S.; Nemeth, S.; Soliz, P.; MacCormick, I.; Taylor, T.; Lewallen, S.; Harding, S.

2016-03-01

Cerebral malaria (CM) is a severe neurological complication associated with malarial infection. Malaria affects approximately 200 million people worldwide, and claims 600,000 lives annually, 75% of whom are African children under five years of age. Because most of these mortalities are caused by the high incidence of CM misdiagnosis, there is a need for an accurate diagnostic to confirm the presence of CM. The retinal lesions associated with malarial retinopathy (MR) such as retinal whitening, vessel discoloration, and hemorrhages, are highly specific to CM, and their detection can improve the accuracy of CM diagnosis. This paper will focus on development of an automated method for the detection of retinal whitening which is a unique sign of MR that manifests due to retinal ischemia resulting from CM. We propose to detect the whitening region in retinal color images based on multiple color and textural features. First, we preprocess the image using color and textural features of the CMYK and CIE-XYZ color spaces to minimize camera reflex. Next, we utilize color features of the HSL, CMYK, and CIE-XYZ channels, along with the structural features of difference of Gaussians. A watershed segmentation algorithm is used to assign each image region a probability of being inside the whitening, based on extracted features. The algorithm was applied to a dataset of 54 images (40 with whitening and 14 controls) that resulted in an image-based (binary) classification with an AUC of 0.80. This provides 88% sensitivity at a specificity of 65%. For a clinical application that requires a high specificity setting, the algorithm can be tuned to a specificity of 89% at a sensitivity of 82%. This is the first published method for retinal whitening detection and combining it with the detection methods for vessel discoloration and hemorrhages can further improve the detection accuracy for malarial retinopathy.

Retinal Image Quality Assessment for Spaceflight-Induced Vision Impairment Study

NASA Technical Reports Server (NTRS)

Vu, Amanda Cadao; Raghunandan, Sneha; Vyas, Ruchi; Radhakrishnan, Krishnan; Taibbi, Giovanni; Vizzeri, Gianmarco; Grant, Maria; Chalam, Kakarla; Parsons-Wingerter, Patricia

2015-01-01

Long-term exposure to space microgravity poses significant risks for visual impairment. Evidence suggests such vision changes are linked to cephalad fluid shifts, prompting a need to directly quantify microgravity-induced retinal vascular changes. The quality of retinal images used for such vascular remodeling analysis, however, is dependent on imaging methodology. For our exploratory study, we hypothesized that retinal images captured using fluorescein imaging methodologies would be of higher quality in comparison to images captured without fluorescein. A semi-automated image quality assessment was developed using Vessel Generation Analysis (VESGEN) software and MATLAB® image analysis toolboxes. An analysis of ten images found that the fluorescein imaging modality provided a 36% increase in overall image quality (two-tailed p=0.089) in comparison to nonfluorescein imaging techniques.

Amalric sign: An augur of ophthalmic artery occlusion

PubMed Central

Hande, Prathibha; Sinha, Babi; Nayak, Shivani; Srinivasan, Srilakshmi; Shetty, Jyothi

2017-01-01

A 75-year-old man presented to us with sudden onset of profound vision loss in his right eye and was identified as suffering from an ophthalmic artery occlusion. Apart from the retinal whitening and box-carring of the retinal arteries, there were characteristic triangular patches of retinal whitening in the midperipheral temporal fundus indicating a previous lateral posterior choroidal artery occlusion. The patient was a chronic smoker and had dyslipidemia. The carotid Doppler study showed complete occlusion of the internal carotid artery. The presence of these triangular patches of retinal whitening or amalric sign can therefore herald a more proximal vessel occlusion. Hence such patients require evaluation on an emergency basis. The characteristic features of the patches on fluorescein angiography and indocyanine green angiography are discussed here. PMID:29044080

To report a case of unilateral proliferative retinopathy following noncerebral malaria with Plasmodium falciparum in Southern India.

PubMed

Verma, Aditya; Krishna, M S

2015-01-01

The retinopathy in association with malaria fever described so far includes retinal hemorrhages, vessel changes, retinal discoloration/whitening and papilledema. Malaria retinopathy has been mostly described in severe cases, associated with Plasmodium falciparum, correlating the patho-physiology of retinal and cerebral manifestations. We report an unusual case of proliferative retinopathy as a manifestation of malaria fever, caused by P. falciparum with no cerebral involvement. The patient had features of unilateral retinal vascular occlusion with proliferative changes and vitreous hemorrhage. To the best of our knowledge, such a case has never been reported so far in the literature. This report highlights the possible occurrence of severe proliferative changes associated with malaria fever, which if diagnosed early can prevent possible blindness.

Amalric sign: An augur of ophthalmic artery occlusion.

PubMed

Hande, Prathibha; Sinha, Babi; Nayak, Shivani; Srinivasan, Srilakshmi; Shetty, Jyothi

2017-10-01

A 75-year-old man presented to us with sudden onset of profound vision loss in his right eye and was identified as suffering from an ophthalmic artery occlusion. Apart from the retinal whitening and box-carring of the retinal arteries, there were characteristic triangular patches of retinal whitening in the midperipheral temporal fundus indicating a previous lateral posterior choroidal artery occlusion. The patient was a chronic smoker and had dyslipidemia. The carotid Doppler study showed complete occlusion of the internal carotid artery. The presence of these triangular patches of retinal whitening or amalric sign can therefore herald a more proximal vessel occlusion. Hence such patients require evaluation on an emergency basis. The characteristic features of the patches on fluorescein angiography and indocyanine green angiography are discussed here.

Tumor necrosis factor and its receptors in the neuroretina and retinal vasculature after ischemia-reperfusion injury in the pig retina

PubMed Central

Gesslein, Bodil; Håkansson, Gisela; Gustafsson, Lotta; Ekström, Per

2010-01-01

Purpose Numerous studies have been performed aimed at limiting the extent of retinal injury after ischemia, but there is still no effective pharmacological treatment available. The aim of the present study was to examine the role of tumor necrosis factor (TNF)α and its receptors (TNF-R1 and TNF-R2), especially considering the neuroretina and the retinal vasculature since the retinal blood vessels are key organs in circulatory failure. Methods Retinal ischemia was induced in pigs by elevating the intraocular pressure to 80 mmHg in one eye, while the other eye served as a control (sham-operated). One hour of ischemia was followed by 5 or 12 h of reperfusion. Retinal circulation was examined in vivo by fundus imaging and fluorescein angiography. TNF-α levels were measured in the vitreous using an angiogenesis antibody array test. The presence and amounts of TNF-α, TNF-R1, and TNF-R2 were investigated in the neuroretina and in the retinal blood vessels, using immunofluorescence staining and real-time PCR techniques. Results Fundus imaging showed obstructed blood flow when ischemia was induced, and reperfusion was clearly visualized using fluorescein angiography. Ischemia resulted in elevated levels of TNF-α protein in the vitreous and TNF-α mRNA in the neuroretina. TNF-α immunofluorescence staining was localized to the Müller cells and the outer plexiform layer of the neuroretina. The expression of TNF-R1 and TNF-R2 mRNA was increased in both the neuroretina and retinal arteries following ischemia-reperfusion. Immunofluorescence double staining for TNF-R1 and either smooth muscle actin or 4',6-diamidino-2-phenylindole (DAPI) indicated expression in the cell membranes of the vascular smooth muscle cells. Double staining with TNF-R1 and calbindin showed localization to the horizontal cells in the outer plexiform layer of the neuroretina. Conclusions Retinal ischemia results in increased expression of TNF-α and its receptors (TNF-R1 and TNF-R2). Cellular signaling pathways involving TNF may be important in the development of retinal injury following ischemia and thus an interesting target for future development of pharmacological therapeutics. PMID:21152396

Retinal Microvascular Network and Microcirculation Assessments in High Myopia.

PubMed

Li, Min; Yang, Ye; Jiang, Hong; Gregori, Giovanni; Roisman, Luiz; Zheng, Fang; Ke, Bilian; Qu, Dongyi; Wang, Jianhua

2017-02-01

To investigate the changes of the retinal microvascular network and microcirculation in high myopia. A cross-sectional, matched, comparative clinical study. Twenty eyes of 20 subjects with nonpathological high myopia (28 ± 5 years of age) with a refractive error of -6.31 ± 1.23 D (mean ± SD) and 20 eyes of 20 age- and sex-matched control subjects (30 ± 6 years of age) with a refractive error of -1.40 ± 1.00 D were recruited. Optical coherence tomography angiography (OCTA) was used to image the retinal microvascular network, which was later quantified by fractal analysis (box counting [D box ], representing vessel density) in both superficial and deep vascular plexuses. The Retinal Function Imager was used to image the retinal microvessel blood flow velocity (BFV). The BFV and microvascular density in the myopia group were corrected for ocular magnification using Bennett's formula. The density of both superficial and deep microvascular plexuses was significantly decreased in the myopia group in comparison to the controls (P < .05). The decrease of the microvessel density of the annular zone (0.6-2.5 mm), measured as D box , was 2.1% and 2.9% in the superficial and deep vascular plexuses, respectively. Microvessel density reached a plateau from 0.5 mm to 1.25 mm from the fovea in both groups, but that in the myopic group was about 3% lower than the control group. No significant differences were detected between the groups in retinal microvascular BFV in either arterioles or venules (P > .05). Microvascular densities in both superficial (r = -0.45, P = .047) and deep (r = -0.54, P = .01) vascular plexuses were negatively correlated with the axial lengths in the myopic eye. No correlations were observed between BFV and vessel density (P > .05). Retinal microvascular decrease was observed in the high myopia subjects, whereas the retinal microvessel BFV remained unchanged. The retinal microvascular network alteration may be attributed to ocular elongation that occurs with the progression of myopia. The novel quantitative analyses of the retinal microvasculature may help to characterize the underlying pathophysiology of myopia and enable early detection and prevention of myopic retinopathy. Copyright © 2016 Elsevier Inc. All rights reserved.

Radial Peripapillary Capillary Network in Patients with Retinitis Pigmentosa: An Optical Coherence Tomography Angiography Study.

PubMed

Mastropasqua, Rodolfo; Borrelli, Enrico; Agnifili, Luca; Toto, Lisa; Di Antonio, Luca; Senatore, Alfonso; Palmieri, Michele; D'Uffizi, Alessandro; Carpineto, Paolo

2017-01-01

To investigate radial peripapillary capillary (RPC) network in patients affected by retinitis pigmentosa (RP). Eleven patients (22 eyes) with previous diagnosis of RP and 16 age-matched healthy subjects (16 eyes) were enrolled. The diagnosis of RP was made based on both clinical features and electrophysiological examination. All patients underwent a complete ophthalmologic examination, including optical coherence tomography angiography and visual field (VF). The primary outcomes were the RPC vessel density in the peripapillary and disk areas; the secondary outcomes were the peripapillary retinal nerve fiber layer (RNFL) thickness and the mean defect at VF. A total of 19 eyes of 11 RP patients (5 males, 6 females) and 16 eyes of 16 healthy subjects (10 males, 6 females) were included for the analysis. RPC vessel density in the disk area was 46.5 ± 7.1% in the RP group and 45.4 ± 10.6% in the control group ( p  = 0.754). RPC vessel density in the peripapillary area was significantly reduced in the RP group after the comparison with the control group (52.5 ± 5.0 and 57.2 ± 5.1%, respectively, p  = 0.011). RNFL thickness was 85.9 ± 20.4 μm in the RP group and 104.0 ± 6.4 μm in the control group ( p  = 0.002). RPC vessel density was significantly correlated with RNFL thickness values in RP patients, both in the disk and in the peripapillary area (Rho = 0.599 and p  = 0.007 in the disk area, Rho = 0.665 and p  = 0.002 in the peripapillary area, respectively). We showed that density of RPC is reduced in these patients in the peripapillary area. Moreover, the RPC vessel density correlates with the RNFL thickness.

Inter-method agreement in retinal blood vessels diameter analysis between Dynamic Vessel Analyzer and optical coherence tomography.

PubMed

Benatti, Lucia; Corvi, Federico; Tomasso, Livia; Mercuri, Stefano; Querques, Lea; Ricceri, Fulvio; Bandello, Francesco; Querques, Giuseppe

2017-06-01

To analyze the inter-methods agreement in arteriovenous ratio (AVR) evaluation between spectral-domain optical coherence tomography (SD-OCT) and Dynamic Vessel Analyzer (DVA). Healthy volunteers underwent DVA and SD-OCT examination. AVR was measured by SD-OCT using the four external lines of the optic nerve head-centered 7-line cube and by DVA using an automated AVR estimation. The mean AVR was calculated, twice, separately by two independent readers for each tool. Twenty-two eyes of 11 healthy subjects (five women and six men, mean age 35) were included. AVR analysis by DVA showed high inter-observer agreement between reader 1 and 2, and high intra-observer agreement for both reader 1 and reader 2. With regard to AVR analysis on SD-OCT, we found high inter-observer agreement between reader 1 and 2, and low intra-observer agreement for reader 2 but high intra-observer agreement for reader 1. Overall, the mean AVR measured on SD-OCT turned out to be significantly higher than mean AVR measured through DVA (reader 1, 0.9023 ± 0.06 vs 0.8036 ± 0.08; p < 0.001, and reader 2, 0.9067 ± 0.06 vs 0.8083 ± 0.05; p= 0.003). No inter-method agreement in AVR could be detected in the present study due to bias in measurements (shift between DVA and SD-OCT). We found significant difference in the two noninvasive methods for AVR measurement, with a tendency for SD-OCT to overestimate retinal vascular caliber in comparison to DVA. This may be useful for achieving greater accuracy in the evaluation of retinal vessel in ocular as well as systemic diseases.

Enhancement of optic cup detection through an improved vessel kink detection framework

NASA Astrophysics Data System (ADS)

Wong, Damon W. K.; Liu, Jiang; Tan, Ngan Meng; Zhang, Zhuo; Lu, Shijian; Lim, Joo Hwee; Li, Huiqi; Wong, Tien Yin

2010-03-01

Glaucoma is a leading cause of blindness. The presence and extent of progression of glaucoma can be determined if the optic cup can be accurately segmented from retinal images. In this paper, we present a framework which improves the detection of the optic cup. First, a region of interest is obtained from the retinal fundus image, and a pallor-based preliminary cup contour estimate is determined. Patches are then extracted from the ROI along this contour. To improve the usability of the patches, adaptive methods are introduced to ensure the patches are within the optic disc and to minimize redundant information. The patches are then analyzed for vessels by an edge transform which generates pixel segments of likely vessel candidates. Wavelet, color and gradient information are used as input features for a SVM model to classify the candidates as vessel or non-vessel. Subsequently, a rigourous non-parametric method is adopted in which a bi-stage multi-resolution approach is used to probe and localize the location of kinks along the vessels. Finally, contenxtual information is used to fuse pallor and kink information to obtain an enhanced optic cup segmentation. Using a batch of 21 images obtained from the Singapore Eye Research Institute, the new method results in a 12.64% reduction in the average overlap error against a pallor only cup, indicating viable improvements in the segmentation and supporting the use of kinks for optic cup detection.

Human Vision-Motivated Algorithm Allows Consistent Retinal Vessel Classification Based on Local Color Contrast for Advancing General Diagnostic Exams.

PubMed

Ivanov, Iliya V; Leitritz, Martin A; Norrenberg, Lars A; Völker, Michael; Dynowski, Marek; Ueffing, Marius; Dietter, Johannes

2016-02-01

Abnormalities of blood vessel anatomy, morphology, and ratio can serve as important diagnostic markers for retinal diseases such as AMD or diabetic retinopathy. Large cohort studies demand automated and quantitative image analysis of vascular abnormalities. Therefore, we developed an analytical software tool to enable automated standardized classification of blood vessels supporting clinical reading. A dataset of 61 images was collected from a total of 33 women and 8 men with a median age of 38 years. The pupils were not dilated, and images were taken after dark adaption. In contrast to current methods in which classification is based on vessel profile intensity averages, and similar to human vision, local color contrast was chosen as a discriminator to allow artery vein discrimination and arterial-venous ratio (AVR) calculation without vessel tracking. With 83% ± 1 standard error of the mean for our dataset, we achieved best classification for weighted lightness information from a combination of the red, green, and blue channels. Tested on an independent dataset, our method reached 89% correct classification, which, when benchmarked against conventional ophthalmologic classification, shows significantly improved classification scores. Our study demonstrates that vessel classification based on local color contrast can cope with inter- or intraimage lightness variability and allows consistent AVR calculation. We offer an open-source implementation of this method upon request, which can be integrated into existing tool sets and applied to general diagnostic exams.

REPRODUCIBILITY OF VESSEL DENSITY MEASUREMENT WITH OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY IN EYES WITH AND WITHOUT RETINOPATHY.

PubMed

You, Qisheng; Freeman, William R; Weinreb, Robert N; Zangwill, Linda; Manalastas, Patricia I C; Saunders, Luke J; Nudleman, Eric

2017-08-01

To determine the intravisit and intervisit reproducibility of optical coherence tomography angiography measurements of macular vessel density in eyes with and without retinal diseases. Fifteen healthy volunteers and 22 patients with retinal diseases underwent repeated optical coherence tomography angiography (Angiovue Imaging System, Optovue Inc) scans after pupil dilation on 2 separate visit days. For each visit day, the eyes were scanned twice. Vessel density defined as the proportion of vessel area with flowing blood over the total measurement area was calculated using Angiovue software. Intravisit and intervisit reproducibility were summarized as coefficient of variations and intraclass correlation coefficients were calculated from variance component models. The coefficient of variations representing the intravisit reproducibility of the superficial macular vessel density measurements for different quadrants on 3 mm × 3-mm scans varied from 2.1% to 4.9% and 3.4% to 6.8% for healthy and diseased eyes, respectively, and for the intervisit it was 2.9% to 5.1% and 4.0% to 6.8%, respectively. The coefficient of variations were lower in healthy eyes than in diseased eyes, lower for intravisit than for intervisit, lower on 3 mm × 3-mm scans than on 6 mm × 6-mm scans, and lower for paracentral subfields than for central subfield. The evidence presented here demonstrates good reproducibility of optical coherence tomography angiography for measurement of superficial macula vessel density in both healthy eyes and eyes with diabetic retinopathy without diabetic macular edema.

Cytomegalovirus retinitis associated with acquired immunodeficiency syndrome.

PubMed

Geng, Shuang; Ye, Jun-jie; Zhao, Jia-liang; Li, Tai-sheng; Han, Yang

2011-04-01

Cytomegalovirus (CMV) retinitis is the most severe intraocular complication that results in total retinal destruction and loss of visual acuity in patients with acquired immunodeficiency syndrome (AIDS). This study aimed to investigate the fundus characteristics, systemic manifestations and therapeutic outcomes of CMV retinitis associated with AIDS. It was a retrospective case series. CMV retinitis was present in 39 eyes (25 patients). Best corrected visual acuities, anterior segment, fundus features, fundus fluorescence angiography (FFA) and CD4(+) T-lymphocyte counts of the patients with CMV retinitis associated with AIDS were analyzed. Intravitreal injections of ganciclovir (400 µg) were performed in 4 eyes (2 patients). Retinal vasculitis, dense, full-thickness, yellow-white lesions along vascular distribution with irregular granules at the border, and hemorrhage on the retinal surface were present in 28 eyes. The vitreous was clear or mildly opaque. Late stage of the retinopathy was demonstrated in 8 eyes characterized as atrophic retina, sclerotic and attenuated vessels, retinal pigment epithelium (RPE) atrophy, and optic nerve atrophy. Retinal detachment was found in 3 eyes. The average CD4(+) T-lymphocyte count in peripheral blood of the patients with CMV retinitis was (30.6 ± 25.3) × 10(6)/L (range, (0 - 85) × 10(6)/L). After intravitreal injections of ganciclovir, visual acuity was improved and fundus lesions regressed. CMV retinitis is the most severe and the most common intraocular complication in patients with AIDS. For the patients with yellow-white retinal lesions, hemorrhage and retinal vasculitis without clear cause, human immunodeficiency virus (HIV) serology should be performed. Routine eye examination is also indicated in HIV positive patients.

Retinal nerve fiber layer thickness map and blood flow pulsation measured with SDOCT

NASA Astrophysics Data System (ADS)

Mujat, Mircea; Chan, Raymond C.; Cense, Barry; Pierce, Mark; Park, Hyle; Joo, Chulmin; Chen, Teresa C.; de Boer, Johannes F.

2006-02-01

Spectral-Domain Optical Coherence Tomography (SDOCT) allows for in-vivo video-rate investigation of biomedical tissue depth structure intended for non-invasive optical diagnostics. It has been suggested that OCT can be used for di-agnosis of glaucoma by measuring the thickness of the Retinal Nerve Fiber Layer (RNLF). We present an automated method for determining the RNFL thickness from a 3-D dataset based on edge detection using a deformable spline algo-rithm. The RNFL thickness map is combined with an integrated reflectance map and retinal cross-sectional images to provide the ophthalmologist with a familiar image for interpreting the OCT data. The video-rate capabilities of our SDOCT system allow for mapping the true retinal topography since motion artifacts are significantly reduced as com-pared to slower time-domain systems. Combined with Doppler Velocimetry, SDOCT also provides information on retinal blood flow dynamics. We analyzed the pulsatile nature of the bidirectional flow dynamics in an artery-vein pair for a healthy volunteer at different locations and for different blood vessel diameters. The Doppler phase shift is determined as the phase difference at the same point of adjacent depth profiles, and is integrated over the area delimited by two circles corresponding to the blood vessels location. Its temporal evolution clearly shows the blood flow pulsatile nature, the cardiac cycle, in both artery and vein. The artery is identified as having a stronger variation of the integrated phase shift. We observe that artery pulsation is always easily detectable, while vein pulsation seems to depend on the veins diameter.

Automated feature extraction for retinal vascular biometry in zebrafish using OCT angiography

NASA Astrophysics Data System (ADS)

Bozic, Ivan; Rao, Gopikrishna M.; Desai, Vineet; Tao, Yuankai K.

2017-02-01

Zebrafish have been identified as an ideal model for angiogenesis because of anatomical and functional similarities with other vertebrates. The scale and complexity of zebrafish assays are limited by the need to manually treat and serially screen animals, and recent technological advances have focused on automation and improving throughput. Here, we use optical coherence tomography (OCT) and OCT angiography (OCT-A) to perform noninvasive, in vivo imaging of retinal vasculature in zebrafish. OCT-A summed voxel projections were low pass filtered and skeletonized to create an en face vascular map prior to connectivity analysis. Vascular segmentation was referenced to the optic nerve head (ONH), which was identified by automatically segmenting the retinal pigment epithelium boundary on the OCT structural volume. The first vessel branch generation was identified as skeleton segments with branch points closest to the ONH, and subsequent generations were found iteratively by expanding the search space outwards from the ONH. Biometric parameters, including length, curvature, and branch angle of each vessel segment were calculated and grouped by branch generation. Despite manual handling and alignment of each animal over multiple time points, we observe distinct qualitative patterns that enable unique identification of each eye from individual animals. We believe this OCT-based retinal biometry method can be applied for automated animal identification and handling in high-throughput organism-level pharmacological assays and genetic screens. In addition, these extracted features may enable high-resolution quantification of longitudinal vascular changes as a method for studying zebrafish models of retinal neovascularization and vascular remodeling.

Cerebral blood velocity and other cardiovascular responses to 2 days of head-down tilt

NASA Technical Reports Server (NTRS)

Frey, Mary A. B.; Mader, Thomas H.; Bagian, James P.; Charles, John B.; Meehan, Richard T.

1993-01-01

Spaceflight induces a cephalad redistribution of fluid volume and blood flow within the human body, and space motion sickness, which is a problem during the first few days of space flight, could be related to these changes in fluid status and in blood flow of the cerebrum and vestibular system. To evaluate possible changes in cerebral blood flow during simulated weightlessness, we measured blood velocity in the middle cerebral artery (MCA) along with retinal vascular diameters, intraocular pressure, impedance cardiography, and sphygmomanometry on nine men (26.2 +/- 6.6 yr) morning and evening for 2 days during continuous 10 deg head-down tilt (HDT). When subjects went from seated to head-down bed rest, their heart rate and retinal diameters decreased, and intraocular pressures increased. After 48 h of HDT, blood flow velocity in the MCA was decreased and thoracic impedance was increased, indicating less fluid in the thorax. Percent changes in blood flow velocities in the MCA after 48 h of HDT were inversely correlated with percent changes in retinal vascular diameters. Blood flow velocities in the MCA were inversely correlated (intersubject) with arterial pressures and retinal vascular diameters. Heart rate, stroke volume, cardiac output, systolic arterial pressure, and at times pulse pressure and blood flow velocities in the MCA were greater in the evening. Total peripheral resistance was higher in the morning. Although cerebral blood velocity is reduced after subjects are head down for 2 days, the inverse relationship with retinal vessel diameters, which have control analogous to that of cerebral vessels, indicates cerebral blood flow is not reduced.

Image Analysis Program for Measuring Particles with the Zeiss CSM 950 Scanning Electron Microscope (SEM)

DTIC Science & Technology

1990-01-01

7 𔄁 . ,: 1& *U _’ ś TECHNICAL REPORT AD NATICK/TR-90/014 (V) N* IMAGE ANALYSIS PROGRAM FOR MEASURING PARTICLES < WITH THE ZEISS CSM 950 SCANNING... image analysis program for measuring particles using the Zeiss CSM 950/Kontron system is as follows: A>CSM calls the image analysis program. Press D to...27 vili LIST OF TABLES TABLE PAGE 1. Image Analysis Program for Measuring 29 Spherical Particles 14 2. Printout of Statistical Data Frcm Table 1 16 3

Analysis by NASA's VESGEN Software of Vascular Branching in the Human Retina with a Ground-Based Microgravity Analog

NASA Technical Reports Server (NTRS)

Parsons-Wingerter, Patricia; Vyas, Ruchi J.; Raghunandan, Sneha; Vu, Amanda C.; Zanello, Susana B.; Ploutz-Snyder, Robert; Taibbi, Giovanni; Vizzeri, Gianmarco

2016-01-01

Significant risks for visual impairment were discovered recently in astronauts following spaceflight, especially after long-duration missions.1 We hypothesize that microgravity-induced fluid shifts result in pathological changes within the retinal vasculature that precede visual and other ocular impairments. We therefore are analyzing retinal vessels in healthy subjects with NASA's VESsel GENeration Analysis (VESGEN) software2 before and after head-down tilt (HDT), a ground-based microgravity analog For our preliminary study of masked images, two groups of venous trees with and without small veins (G=7) were clearly identified by VESGEN analysis. Upon completing all images and unmasking the subject status of pre- and post- HDT, we will determine whether differences in the presence or absence of small veins are important correlates, and perhaps reliable predictors, of other ocular and physiological adaptations to prolonged HDT and microgravity. Greater peripapillary retinal thickening was measured following 70-day HDT bed rest than 14-day HDT bed rest, suggesting that time of HDT may increase the amount of optic disc swelling.3 Spectralis OCT detected retinal nerve fiber layer thickening post HDT, without clinical signs of optic disc edema. Such changes may have resulted from HDT-induced cephalad fluid shifts. Clinical methods for examining adaptive microvascular remodeling in the retina to microgravity space flight are currently not established.

Retinal vascular changes in preterm infants: heart and lung diseases and plus disease.

PubMed

Arriola-Lopez, Andrea Elizabeth; Martinez-Perez, M Elena; Martinez-Castellanos, Maria Ana

2017-12-01

To report the retinal vascular features of preterm infants with congenital heart disease (CHD), lung disease (pulmonary hypertension [PH] and bronchopulmonary dysplasia [BPD]), and ROP with plus disease to determine whether these disease entities are distinguishable on the basis of retinal vessel morphology. The medical records of preterm infants with CHD, lung disease, and ROP with plus disease were reviewed retrospectively. Qualitative vascular findings were validated using computer-based software to analyze 25 representative images, each corresponding to one infant's eye. The images were organized into five groups, based on clinical information. Vessel diameter (d) and tortuosity index (TI) were measured. A total of 106 infants (mean gestational age, 30.5 ± 2.22 weeks) were initially included. Ophthalmologic evaluation of preterm infants with CHD and lung diseases showed vascular tortuosity without vasodilation at the posterior pole as well as in the periphery. Quantitative analysis showed that venular diameter was significantly increased in the plus disease group (P = 0.0022) compared to other groups. There was significantly less tortuosity in both arterioles and venules in BPD (P < 0.001, P = 0.0453) compared with plus group. The patterns of retinal vascular tortuosity observed in preterm infants may be unique to different systemic congestive conditions and could have therapeutic implications. Copyright © 2017 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

Molecular imaging reveals elevated VEGFR-2 expression in retinal capillaries in diabetes: a novel biomarker for early diagnosis.

PubMed

Sun, Dawei; Nakao, Shintaro; Xie, Fang; Zandi, Souska; Bagheri, Abouzar; Kanavi, Mozhgan Rezaei; Samiei, Shahram; Soheili, Zahra-Soheila; Frimmel, Sonja; Zhang, Zhongyu; Ablonczy, Zsolt; Ahmadieh, Hamid; Hafezi-Moghadam, Ali

2014-09-01

Diabetic retinopathy (DR) is a microvascular complication of diabetes and a leading cause of vision loss. Biomarkers and methods for early diagnosis of DR are urgently needed. Using a new molecular imaging approach, we show up to 94% higher accumulation of custom designed imaging probes against vascular endothelial growth factor receptor 2 (VEGFR-2) in retinal and choroidal vessels of diabetic animals (P<0.01), compared to normal controls. More than 80% of the VEGFR-2 in the diabetic retina was in the capillaries, compared to 47% in normal controls (P<0.01). Angiography in rabbit retinas revealed microvascular capillaries to be the location for VEGF-A-induced leakage, as expressed by significantly higher rate of fluorophore spreading with VEGF-A injection when compared to vehicle control (26±2 vs. 3±1 μm/s, P<0.05). Immunohistochemistry showed VEGFR-2 expression in capillaries of diabetic animals but not in normal controls. Macular vessels from diabetic patients (n=7) showed significantly more VEGFR-2 compared to nondiabetic controls (n=5) or peripheral retinal regions of the same retinas (P<0.01 in both cases). Here we introduce a new approach for early diagnosis of DR and VEGFR-2 as a molecular marker. VEGFR-2 could become a key diagnostic target, one that might help to prevent retinal vascular leakage and proliferation in diabetic patients. © FASEB.

[Effects of different oxygen inhalation modes on retinal vessels development in neonatal mice].

PubMed

Wang, Yu-Huan; Chen, Chao; Shi, Wen-Jing; Xiao, Hong-Lei; Tong, Bei-Yan; Zhou, Guo-Min

2006-04-01

This study was designed to investigate the effects of different oxygen inhalation modes on retinal vessels development in neonatal mice in order to provide experimental data for proper oxygen therapy for premature infants. A total of 144 postnatal day (P) 7 C57BL/6J mice were randomly assigned into 6 groups according to different oxygen inhalation modes (n=24). Experimental group 1 was exposed to 30%, 40%, 50%, 60% and 75% oxygen in turn for one day respectively, followed by room air exposure for 5 days. Experimental group 2 was exposed to 75%, 60%, 50%, 40% and 30% oxygen in turn for one day respectively, followed by room air exposure for 5 days. Experimental group 3 was exposed to 75% oxygen for 5 days, followed by room air exposure for 5 days. Experimental group 4 was exposed to 75% oxygen for 5 days, 50% oxygen for 2 days and 30% oxygen for 2 days, then room air exposure for 6 days. The supplemental 75% oxygen and room air recovering was performed alternately for the mice in Experimental group 5 for 3 times and then room air exposure for 5 days. The Control group was exposed to room air for consecutive 10 days. The retinal vascular development and proliferation were evaluated by the retinal flat-mounts (ADPase stained retina) and cross-section. The peripheral vascular pattern was clear, and a few avascular areas were seen in the Control group at P12. At P14 the avascular area disappeared. At P17, the entire vascular pattern became completely normal. In the Experimental groups 1, 3 and 5, the central vessels became tortuous and constricted and the central avascular area increased at P12. At P14, neovascularization was seen peaking at P17 in the Experimental groups 1, 3 and 5. In the Experimental group 4, the central avascular area increased and neovascularization was seen at P14, but the central avascular area was reduced and abnormal neovascularization disappeared, with slight constriction of the deep vessels, at P17. Five days later the vascular pattern became almost normal in the Experimental group 4. The retinal vascular form of the Experimental group 2 was similar to that of the Control group. The average number of neovascular nuclei extending into the vitreous per cross-section in the Experimental groups 1, 2, 3, 4, and 5 and the Control group was 49.50 +/- 1.36, 5.17 +/- 0.67, 47.68 +/- 4.70, 5.74 +/- 2.37, 29.15 +/- 2.48, and 1.22 +/- 0.20 respectively. There were significant differences between the Experimental groups 1, 3, 5 and the Control group (P < 0.05). The effects of different oxygen inhalation modes on the retinal vessels development in neonatal mice were different. The obvious fluctuation of inhaled oxygen concentration and abrupt stop of supplemental oxygen after high levels of supplemental oxygen may severely affect the development of retina vascular, leading to the pathologic changes similar to retinopathy of prematurity.

Ophthalmoscopy

MedlinePlus

... done if you have signs or symptoms of high blood pressure, diabetes, or other diseases that affect the blood vessels. ... conditions: Viral inflammation of the retina ( CMV retinitis ) ... blood pressure Loss of sharp vision due to macular degeneration ...

Retinal Arterioles in Hypo-, Normo-, and Hypertensive Subjects Measured Using Adaptive Optics.

PubMed

Hillard, Jacob G; Gast, Thomas J; Chui, Toco Y P; Sapir, Dan; Burns, Stephen A

2016-08-01

Small artery and arteriolar walls thicken due to elevated blood pressure. Vascular wall thickness show a correlation with hypertensive subject history and risk for stroke and cardiovascular events. The inner and outer diameter of retinal arterioles from less than 10 to over 150 μm were measured using a multiply scattered light adaptive optics scanning laser ophthalmoscope (AOSLO). These measurements were made on three populations, one with habitual blood pressures less than 100/70 mm Hg, one with normal blood pressures without medication, and one with managed essential hypertension. The wall to lumen ratio was largest for the smallest arterioles for all three populations. Data from the hypotensive group had a linear relationship between outer and inner diameters ( r 2 = 0.99) suggesting a similar wall structure in individuals prior to elevated blood pressures. Hypertensive subjects fell below the 95% confidence limits for the hypotensive relationship and had larger wall to lumen ratios and the normotensive group results fell between the other two groups. High-resolution retinal imaging of subjects with essential hypertension showed a significant decrease in vessel inner diameter for a given outer diameter, and increases in wall to lumen ratio and wall cross-sectional areas over the entire range of vessel diameters and suggests that correcting for vessel size may improve the ability to identify significant vascular changes. High-resolution imaging allows precise measurement of vasculature and by comparing results across risk populations may allow improved identification of individuals undergoing hypertensive arterial wall remodeling.

Integration of retinal image sequences

NASA Astrophysics Data System (ADS)

Ballerini, Lucia

1998-10-01

In this paper a method for noise reduction in ocular fundus image sequences is described. The eye is the only part of the human body where the capillary network can be observed along with the arterial and venous circulation using a non invasive technique. The study of the retinal vessels is very important both for the study of the local pathology (retinal disease) and for the large amount of information it offers on systematic haemodynamics, such as hypertension, arteriosclerosis, and diabetes. In this paper a method for image integration of ocular fundus image sequences is described. The procedure can be divided in two step: registration and fusion. First we describe an automatic alignment algorithm for registration of ocular fundus images. In order to enhance vessel structures, we used a spatially oriented bank of filters designed to match the properties of the objects of interest. To evaluate interframe misalignment we adopted a fast cross-correlation algorithm. The performances of the alignment method have been estimated by simulating shifts between image pairs and by using a cross-validation approach. Then we propose a temporal integration technique of image sequences so as to compute enhanced pictures of the overall capillary network. Image registration is combined with image enhancement by fusing subsequent frames of a same region. To evaluate the attainable results, the signal-to-noise ratio was estimated before and after integration. Experimental results on synthetic images of vessel-like structures with different kind of Gaussian additive noise as well as on real fundus images are reported.

The Extract of Aster Koraiensis Prevents Retinal Pericyte Apoptosis in Diabetic Rats and Its Active Compound, Chlorogenic Acid Inhibits AGE Formation and AGE/RAGE Interaction

PubMed Central

Kim, Junghyun; Jo, Kyuhyung; Lee, Ik-Soo; Kim, Chan-Sik; Kim, Jin Sook

2016-01-01

Retinal capillary cell loss is a hallmark of early diabetic retinal changes. Advanced glycation end products (AGEs) are believed to contribute to retinal microvascular cell loss in diabetic retinopathy. In this study, the protective effects of Aster koraiensis extract (AKE) against damage to retinal vascular cells were investigated in streptozotocin (STZ)-induced diabetic rats. To examine this issue further, AGE accumulation, nuclear factor-kappaB (NF-κB) and inducible nitric oxide synthase (iNOS) were investigated using retinal trypsin digests from streptozotocin-induced diabetic rats. In the diabetic rats, TUNEL (Terminal deoxynucleotidyl transferase mediated dUTP Nick End Labeling)-positive retinal microvascular cells were markedly increased. Immunohistochemical studies revealed that AGEs were accumulated within the retinal microvascular cells, and this accumulation paralleled the activation of NF-κB and the expression of iNOS in the diabetic rats. However, AKE prevented retinal microvascular cell apoptosis through the inhibition of AGE accumulation and NF-κB activation. Moreover, to determine the active compounds of AKE, two major compounds, chlorogenic acid and 3,5-di-O-caffeoylquinic acid, were tested in an in vitro assay. Among these compounds, chlorogenic acid significantly reduced AGE formation as well as AGE/RAGE (receptor for AGEs) binding activity. These results suggest that AKE, particularly chlorogenic acid, is useful in inhibiting AGE accumulation in retinal vessels and exerts a preventive effect against the injuries of diabetic retinal vascular cells. PMID:27657123

Alteration of Developmental and Pathological Retinal Angiogenesis in angptl4-deficient Mice*

PubMed Central

Perdiguero, Elisa Gomez; Galaup, Ariane; Durand, Mélanie; Teillon, Jérémie; Philippe, Josette; Valenzuela, David M.; Murphy, Andrew J.; Yancopoulos, George D.; Thurston, Gavin; Germain, Stéphane

2011-01-01

Proper vessel maturation, remodeling of endothelial junctions, and recruitment of perivascular cells is crucial for establishing and maintaining vessel functions. In proliferative retinopathies, hypoxia-induced angiogenesis is associated with disruption of the vascular barrier, edema, and vision loss. Therefore, identifying factors that regulate vascular maturation is critical to target pathological angiogenesis. Given the conflicting role of angiopoietin-like-4 (ANGPTL4) reported in the current literature using gain of function systems both in vitro and in vivo, the goal of this study was to characterize angiogenesis, focusing on perinatal retinal vascularization and pathological circumstances in angpl4-deficient mice. We report altered organization of endothelial junctions and pericyte coverage, both leading to impaired angiogenesis and increased vascular leakage that were eventually caught up, suggesting a delay in vessel maturation. In a model of oxygen-induced retinopathy, pathological neovascularization, which results from tissue hypoxia, was also strongly inhibited in angptl4-deficient mice. This study therefore shows that ANGPTL4 tunes endothelial cell junction organization and pericyte coverage and controls vascular permeability and angiogenesis, both during development and in pathological conditions. PMID:21832056

RI in central retinal artery as assessed by CDI does not correspond to retinal vascular resistance.

PubMed

Polska, E; Kircher, K; Ehrlich, P; Vecsei, P V; Schmetterer, L

2001-04-01

The aim of the present study was to investigate the association between ultrasound Doppler measurements of resistive index (RI) in the central retinal artery and retinal vascular resistance (R) assessed with laser Doppler velocimetry, vessel size measurement, and calculation of ocular perfusion pressure (PP) in healthy subjects. An increase in vascular resistance was induced by inhalation of 100% O(2). During hyperoxia no significant changes in PP were observed. Mean flow velocity in main retinal veins was reduced by -27.5 +/- 2.0%. The average decrease in diameter was -11.5 +/- 1.0%. R, which was calculated as the ratio of PP to flow rate, increased by 97.6 +/- 7.7%. RI increased as well, but the effect was much smaller (6.6 +/- 2.2%). In addition, a negative correlation was found between baseline values of R and RI (r = -0.83). During hyperoxia R and RI were not associated. In conclusion, our data indicate that RI as assessed with color Doppler imaging in the central retinal artery is not an adequate measure of R.

Zeiss ΣIGMA VP-FE-SEM User Guide

EPA Science Inventory

User guide for analyzing carbon based nanomaterials on a Zeiss Sigma microscope. The guide includes helpful steps for sample preparation and loading. Specific topics utilizing the scanning electron microscope are instrumentation startup and imagining. A variety of detectors in...

Retinal imaging using adaptive optics technology☆

PubMed Central

Kozak, Igor

2014-01-01

Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effect of wave front distortions. Retinal imaging using AO aims to compensate for higher order aberrations originating from the cornea and the lens by using deformable mirror. The main application of AO retinal imaging has been to assess photoreceptor cell density, spacing, and mosaic regularity in normal and diseased eyes. Apart from photoreceptors, the retinal pigment epithelium, retinal nerve fiber layer, retinal vessel wall and lamina cribrosa can also be visualized with AO technology. Recent interest in AO technology in eye research has resulted in growing number of reports and publications utilizing this technology in both animals and humans. With the availability of first commercially available instruments we are making transformation of AO technology from a research tool to diagnostic instrument. The current challenges include imaging eyes with less than perfect optical media, formation of normative databases for acquired images such as cone mosaics, and the cost of the technology. The opportunities for AO will include more detailed diagnosis with description of some new findings in retinal diseases and glaucoma as well as expansion of AO into clinical trials which has already started. PMID:24843304

Association of Retinopathy and Retinal Microvascular Abnormalities With Stroke and Cerebrovascular Disease.

PubMed

Hughes, Alun D; Falaschetti, Emanuela; Witt, Nicholas; Wijetunge, Sumangali; Thom, Simon A McG; Tillin, Therese; Aldington, Steve J; Chaturvedi, Nish

2016-11-01

Abnormalities of the retinal circulation may be associated with cerebrovascular disease. We investigated associations between retinal microvascular abnormalities and (1) strokes and subclinical cerebral infarcts and (2) cerebral white matter lesions in a UK-based triethnic population-based cohort. A total of 1185 participants (age, 68.8±6.1 years; 77% men) underwent retinal imaging and cerebral magnetic resonance imaging. Cerebral infarcts and white matter hyperintensities were identified on magnetic resonance imaging, retinopathy was graded, and retinal vessels were measured. Higher retinopathy grade (odds ratio [OR], 1.40 [95% confidence interval (95% CI), 1.16-1.70]), narrower arteriolar diameter (OR, 0.98 [95% CI, 0.97-0.99]), fewer symmetrical arteriolar bifurcations (OR, 0.84 [95% CI, 0.75-0.95]), higher arteriolar optimality deviation (OR, 1.16 [95% CI, 1.00-1.34]), and more tortuous venules (OR, 1.20 [95% CI, 1.09-1.32]) were associated with strokes/infarcts and white matter hyperintensities. Associations with quantitative retinal microvascular measures were independent of retinopathy. Abnormalities of the retinal microvasculature are independently associated with stroke, cerebral infarcts, and white matter lesions. © 2016 American Heart Association, Inc.

The design and integration of retinal CAD-SR to diabetes patient ePR system

NASA Astrophysics Data System (ADS)

Wu, Huiqun; Wei, Yufang; Liu, Brent J.; Shang, Yujuan; Shi, Lili; Jiang, Kui; Dong, Jiancheng

2017-03-01

Diabetic retinopathy (DR) is one of the serious complications of diabetes that could lead to blindness. Digital fundus camera is often used to detect retinal changes but the diagnosis relies too much on ophthalmologist's experience. Based on our previously developed algorithms for quantifying retinal vessels and lesions, we developed a computer aided detection-structured report (CAD-SR) template and implemented it into picture archiving and communication system (PACS). Furthermore, we mapped our CAD-SR into HL7 CDA to integrate CAD findings into diabetes patient electronic patient record (ePR) system. Such integration could provide more quantitative features from fundus image into ePR system, which is valuable for further data mining researches.

Fast and automatic algorithm for optic disc extraction in retinal images using principle-component-analysis-based preprocessing and curvelet transform.

PubMed

Shahbeig, Saleh; Pourghassem, Hossein

2013-01-01

Optic disc or optic nerve (ON) head extraction in retinal images has widespread applications in retinal disease diagnosis and human identification in biometric systems. This paper introduces a fast and automatic algorithm for detecting and extracting the ON region accurately from the retinal images without the use of the blood-vessel information. In this algorithm, to compensate for the destructive changes of the illumination and also enhance the contrast of the retinal images, we estimate the illumination of background and apply an adaptive correction function on the curvelet transform coefficients of retinal images. In other words, we eliminate the fault factors and pave the way to extract the ON region exactly. Then, we detect the ON region from retinal images using the morphology operators based on geodesic conversions, by applying a proper adaptive correction function on the reconstructed image's curvelet transform coefficients and a novel powerful criterion. Finally, using a local thresholding on the detected area of the retinal images, we extract the ON region. The proposed algorithm is evaluated on available images of DRIVE and STARE databases. The experimental results indicate that the proposed algorithm obtains an accuracy rate of 100% and 97.53% for the ON extractions on DRIVE and STARE databases, respectively.

Retinal oxygen saturation before and after glaucoma surgery.

PubMed

Nitta, Eri; Hirooka, Kazuyuki; Shimazaki, Takeru; Sato, Shino; Ukegawa, Kaori; Nakano, Yuki; Tsujikawa, Akitaka

2017-08-01

This study compared retinal vessel oxygen saturation before and after glaucoma surgery. Retinal oxygen saturation in glaucoma patients was measured using a non-invasive spectrophotometric retinal oximeter. Adequate image quality was found in 49 of the 108 consecutive glaucoma patients recruited, with 30 undergoing trabeculectomy, 11 EX-PRESS and eight trabeculotomy. Retinal oxygen saturation measurements in the retinal arterioles and venules were performed at 1 day prior to and at approximately 10 days after surgery. Statistical analysis was performed using a Student's t-test. After glaucoma surgery, intraocular pressure (IOP) decreased from 19.8 ± 7.7 mmHg to 9.0 ± 5.7 mmHg (p < 0.001). Although oxygen saturation in retinal arterioles remained unchanged before and after surgery (104.7 ± 10.6% before and 105.4 ± 9.3% after surgery, p = 0.58), the oxygen saturation in the venules increased from 54.9 ± 7.4% to 57.4 ± 5.7% (p = 0.01). Intraocular pressure (IOP) decreases caused by glaucoma surgery had an effect on the retinal venous oxygen saturation. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Retinitis pigmentosa, pigmentary retinopathies, and neurologic diseases.

PubMed

Bhatti, M Tariq

2006-09-01

Retinitis pigmentosa (RP) refers to a group of inherited retinal diseases with phenotypic and genetic heterogeneity. The pathophysiologic basis of the progressive visual loss in patients with RP is not completely understood but is felt to be due to a primary retinal photoreceptor cell degenerative process mainly affecting the rods of the peripheral retina. In most cases RP is seen in isolation (nonsyndromic), but in some other cases it may be a part of a genetic, metabolic, or neurologic syndrome or disorder. Nyctalopia, or night blindness, is the most common symptom of RP. The classic fundus appearance of RP includes retinal pigment epithelial cell changes resulting in retinal hypo- or hyperpigmentation ("salt-and-pepper"), retinal granularity, and bone spicule formation. The retinal vessels are often narrowed or attenuated and there is a waxy pallor appearance of the optic nerve head. Electroretinography will demonstrate rod and cone photoreceptor cell dysfunction and is a helpful test in the diagnosis and monitoring of patients with RP. A detailed history with pedigree analysis, a complete ocular examination, and the appropriate paraclinical testing should be performed in patients complaining of visual difficulties at night or in dim light. This review discusses the clinical manifestations of RP as well as describing the various systemic diseases, with a special emphasis on neurologic diseases, associated with a pigmentary retinopathy.

Critical Endothelial Regulation by LRP5 during Retinal Vascular Development.

PubMed

Huang, Wei; Li, Qing; Amiry-Moghaddam, Mahmood; Hokama, Madoka; Sardi, Sylvia H; Nagao, Masashi; Warman, Matthew L; Olsen, Bjorn R

2016-01-01

Vascular abnormalities in the eye are the leading cause of many forms of inherited and acquired human blindness. Loss-of-function mutations in the Wnt-binding co-receptor LRP5 leads to aberrant ocular vascularization and loss of vision in genetic disorders such as osteoporosis-pseudoglioma syndrome. The canonical Wnt-β-catenin pathway is known to regulate retinal vascular development. However, it is unclear what precise role LPR5 plays in this process. Here, we show that loss of LRP5 function in mice causes retinal hypovascularization during development as well as retinal neovascularization in adulthood with disorganized and leaky vessels. Using a highly specific Flk1-CreBreier line for vascular endothelial cells, together with several genetic models, we demonstrate that loss of endothelium-derived LRP5 recapitulates the retinal vascular defects in Lrp5-/- mice. In addition, restoring LRP5 function only in endothelial cells in Lrp5-/- mice rescues their retinal vascular abnormalities. Furthermore, we show that retinal vascularization is regulated by LRP5 in a dosage dependent manner and does not depend on LRP6. Our study provides the first direct evidence that endothelium-derived LRP5 is both necessary and sufficient to mediate its critical role in the development and maintenance of retinal vasculature.

Critical Endothelial Regulation by LRP5 during Retinal Vascular Development

PubMed Central

Huang, Wei; Li, Qing; Amiry-Moghaddam, Mahmood; Hokama, Madoka; Sardi, Sylvia H.; Nagao, Masashi; Warman, Matthew L.; Olsen, Bjorn R.

2016-01-01

Vascular abnormalities in the eye are the leading cause of many forms of inherited and acquired human blindness. Loss-of-function mutations in the Wnt-binding co-receptor LRP5 leads to aberrant ocular vascularization and loss of vision in genetic disorders such as osteoporosis-pseudoglioma syndrome. The canonical Wnt-β-catenin pathway is known to regulate retinal vascular development. However, it is unclear what precise role LPR5 plays in this process. Here, we show that loss of LRP5 function in mice causes retinal hypovascularization during development as well as retinal neovascularization in adulthood with disorganized and leaky vessels. Using a highly specific Flk1-CreBreier line for vascular endothelial cells, together with several genetic models, we demonstrate that loss of endothelium-derived LRP5 recapitulates the retinal vascular defects in Lrp5-/- mice. In addition, restoring LRP5 function only in endothelial cells in Lrp5-/- mice rescues their retinal vascular abnormalities. Furthermore, we show that retinal vascularization is regulated by LRP5 in a dosage dependent manner and does not depend on LRP6. Our study provides the first direct evidence that endothelium-derived LRP5 is both necessary and sufficient to mediate its critical role in the development and maintenance of retinal vasculature. PMID:27031698

Abnormal vascularization in mouse retina with dysregulated retinal cholesterol homeostasis

PubMed Central

Omarova, Saida; Charvet, Casey D.; Reem, Rachel E.; Mast, Natalia; Zheng, Wenchao; Huang, Suber; Peachey, Neal S.; Pikuleva, Irina A.

2012-01-01

Several lines of evidence suggest a link between age-related macular degeneration and retinal cholesterol maintenance. Cytochrome P450 27A1 (CYP27A1) is a ubiquitously expressed mitochondrial sterol 27-hydroxylase that plays an important role in the metabolism of cholesterol and cholesterol-related compounds. We conducted a comprehensive ophthalmic evaluation of mice lacking CYP27A1. We found that the loss of CYP27A1 led to dysregulation of retinal cholesterol homeostasis, including unexpected upregulation of retinal cholesterol biosynthesis. Cyp27a1–/– mice developed retinal lesions characterized by cholesterol deposition beneath the retinal pigment epithelium. Further, Cyp27a1-null mice showed pathological neovascularization, which likely arose from both the retina and the choroid, that led to the formation of retinal-choroidal anastomosis. Blood flow alterations and blood vessel leakage were noted in the areas of pathology. The Cyp27a1–/– retina was hypoxic and had activated Müller cells. We suggest a mechanism whereby abolished sterol 27-hydroxylase activity leads to vascular changes and identify Cyp27a1–/– mice as a model for one of the variants of type 3 retinal neovascularization occurring in some patients with age-related macular degeneration. PMID:22820291

Optical coherence tomography, scanning laser polarimetry and confocal scanning laser ophthalmoscopy in retinal nerve fiber layer measurements of glaucoma patients.

PubMed

Fanihagh, Farsad; Kremmer, Stephan; Anastassiou, Gerasimos; Schallenberg, Maurice

2015-01-01

To determine the correlations and strength of association between different imaging systems in analyzing the retinal nerve fiber layer (RNFL) of glaucoma patients: optical coherence tomography (OCT), scanning laser polarimetry (SLP) and confocal scanning laser ophthalmoscopy (CSLO). 114 eyes of patients with moderate open angle glaucoma underwent spectral domain OCT (Topcon SD-OCT 2000 and Zeiss Cirrus HD-OCT), SLP (GDx VCC and GDx Pro) and CSLO (Heidelberg Retina Tomograph, HRT 3). Correlation coefficients were calculated between the structural parameters yielded by these examinations. The quantitative relationship between the measured RNFL thickness globally and for the four regions (superior, inferior, nasal, temporal) were evaluated with different regression models for all used imaging systems. The strongest correlation of RNFL measurements was found between devices using the same technology like GDx VCC and GDx Pro as well as Topcon OCT and Cirrus OCT. In glaucoma patients, the strongest associations (R²) were found between RNFL measurements of the two optical coherence tomography devices Topcon OCT and Cirrus OCT (R² = 0.513) and between GDx VCC and GDx Pro (R² = 0.451). The results of the OCTs and GDX Pro also had a strong quantitative relationship (Topcon OCT R² = 0.339 and Cirrus OCT R² = 0.347). GDx VCC and the OCTs showed a mild to moderate association (Topcon OCT R² = 0.207 and Cirrus OCT R² = 0.258). The confocal scanning laser ophthalmoscopy (HRT 3) had the lowest association to all other devices (Topcon OCT R² = 0.254, Cirrus OCT R² = 0.158, GDx Pro R² = 0.086 and GDx VCC R² = 0.1). The measurements of the RNFL in glaucoma patients reveal a high correlation of OCT and GDx devices because OCTs can measure all major retinal layers and SLP can detect nerve fibers allowing a comparison between the results of this devices. However, CSLO by means of HRT topography can only measure height values of the retinal surface but it cannot distinguish between different retinal layers. This may explain the rather poor correlations and associations between CSLO measurements and those of all other imaging devices which makes it difficult to compare HRT 3 nerve fiber data. These correlations are important in clinical routine especially when different techniques are used in the follow-up of glaucoma patients.

Tlx acts as a proangiogenic switch by regulating extracellular assembly of fibronectin matrices in retinal astrocytes.

PubMed

Uemura, Akiyoshi; Kusuhara, Sentaro; Wiegand, Stanley J; Yu, Ruth T; Nishikawa, Shin-ichi

2006-02-01

In response to hypoxia, hypoxia-inducible factors act as the primary proangiogenic triggers by regulating transcription levels of target genes, including VEGF. However, little is known about the specific factors that control other components of the angiogenic process, particularly formation of matrix scaffolds that promote adhesion and migration of endothelial cells. We show that in the postnatal mouse retina, the orphan nuclear receptor tailless (Tlx) is strongly expressed in the proangiogenic astrocytes, which secrete VEGF and fibronectin. Tlx expression by retinal astrocytes is controlled by oxygen concentration and rapidly downregulated upon contact with blood vessels. In mice null for Tlx, retinal astrocytes maintain VEGF expression; however, the extracellular assembly of fibronectin matrices by astrocytes is severely impaired, leading to defective scaffold formation and a complete failure of normal retinal vascular development. This work identifies Tlx as an essential component of the molecular network involved in the hypoxia-inducible proangiogenic switch in retinal astrocytes.

Tlx acts as a proangiogenic switch by regulating extracellular assembly of fibronectin matrices in retinal astrocytes

PubMed Central

Uemura, Akiyoshi; Kusuhara, Sentaro; Wiegand, Stanley J.; Yu, Ruth T.; Nishikawa, Shin-Ichi

2006-01-01

In response to hypoxia, hypoxia-inducible factors act as the primary proangiogenic triggers by regulating transcription levels of target genes, including VEGF. However, little is known about the specific factors that control other components of the angiogenic process, particularly formation of matrix scaffolds that promote adhesion and migration of endothelial cells. We show that in the postnatal mouse retina, the orphan nuclear receptor tailless (Tlx) is strongly expressed in the proangiogenic astrocytes, which secrete VEGF and fibronectin. Tlx expression by retinal astrocytes is controlled by oxygen concentration and rapidly downregulated upon contact with blood vessels. In mice null for Tlx, retinal astrocytes maintain VEGF expression; however, the extracellular assembly of fibronectin matrices by astrocytes is severely impaired, leading to defective scaffold formation and a complete failure of normal retinal vascular development. This work identifies Tlx as an essential component of the molecular network involved in the hypoxia-inducible proangiogenic switch in retinal astrocytes. PMID:16424942

Carotid artery Doppler ultrasonography in retinal macroaneurysms.

PubMed

Thurairajan, G; Potamitis, T; Naylor, G; Gibson, J

1998-01-01

It is postulated that retinal arterial macroaneurysms (RAMs) occur at the site of incomplete embolic occlusion of a branch retinal artery. Embolic events of the retinal vessels are related to the state of the carotid artery tree and therefore Doppler ultrasonography of the carotid arteries in these patients is of particular interest. We have examined 13 patients with retinal artery macroaneurysms with carotid artery Doppler ultrasonography (CADU). Eight of these patients (61.5%) exhibited atheromatous plaques on the same side as the RAM with a moderate degree of arterial narrowing. Although our group of patients did not show advanced carotid artery disease, alterations of the arterial wall found at the level of the carotid artery were higher than expected in a similar hypertensive population. To our knowledge this is the first study of the carotid arterial tree in these patients. Our results support the theory that RAMs may be of embolic origin. Furthermore they demonstrate that CADU is a useful investigation in patients with RAMs.

Segmentation and feature extraction of retinal vascular morphology

NASA Astrophysics Data System (ADS)

Leopold, Henry A.; Orchard, Jeff; Zelek, John; Lakshminarayanan, Vasudevan

2017-02-01

Analysis of retinal fundus images is essential for physicians, optometrists and ophthalmologists in the diagnosis, care and treatment of patients. The first step of almost all forms of automated fundus analysis begins with the segmentation and subtraction of the retinal vasculature, while analysis of that same structure can aid in the diagnosis of certain retinal and cardiovascular conditions, such as diabetes or stroke. This paper investigates the use of a Convolutional Neural Network as a multi-channel classifier of retinal vessels using DRIVE, a database of fundus images. The result of the network with the application of a confidence threshold was slightly below the 2nd observer and gold standard, with an accuracy of 0.9419 and ROC of 0.9707. The output of the network with on post-processing boasted the highest sensitivity found in the literature with a score of 0.9568 and a good ROC score of 0.9689. The high sensitivity of the system makes it suitable for longitudinal morphology assessments, disease detection and other similar tasks.

Delineation of the vitreous and posterior hyaloid using bromophenol blue.

PubMed

Haritoglou, Christos; Strauss, Rupert; Priglinger, Siegfried G; Kreutzer, Thomas; Kampik, Anselm

2008-02-01

To describe visualization of the vitreous and the posterior hyaloid membrane using bromophenol blue during vitrectomy for macular hole and retinal detachment. Six patients with macular holes and four with retinal detachments were included in the study. Before and after surgery, complete clinical examination, including funduscopy and measurements of best-corrected visual acuity and intraocular pressure, was performed. Additional functional tests, such as fluorescein angiography, optical coherence tomography (Stratus OCT; Carl Zeiss Meditec, Jena, Germany, Germany), Goldmann perimetry, and multifocal electroretinography as well as photography of the posterior pole, were performed for macular hole patients. Bromophenol blue was used in concentrations of 0.2%. During macular hole surgery, the dye was injected into the air-filled globe, while during surgery for retinal detachment, the globe was partially filled with perfluorocarbon before dye injection after induction of a posterior vitreous detachment to stain the vitreous peripherally. Bromophenol blue provided sufficient staining of the attached posterior hyaloid membrane and vitreous remnants in the periphery. This was especially helpful for patients in whom a posterior vitreous detachment could not be induced mechanically by suction using the vitrectomy probe alone, as seen in three of six interventions for a macular hole in this series. In addition, staining of the vitreous or vitreous remnants in the periphery and at the vitreous base was seen in all patients and helped to completely remove the vitreous in a controlled fashion. After macular hole surgery, increase of visual acuity from 20/100 (mean) to 20/40 was seen during follow-up up to 6 months. In one case, the hole persisted and required a second operation. Finally, closure of the hole was achieved in all patients. After retinal detachment surgery, reattachment was achieved in all cases. No dye-related adverse events were seen during follow-up as shown by the functional tests (visual acuity measurement, electroretinography, and perimetry) applied. Delineation of the vitreous and the posterior hyaloid using bromophenol blue staining greatly facilitates vitreoretinal procedures. Bromophenol blue appeared to be a very helpful and safe tool to visualize the posterior hyaloid membrane in macular hole surgery and assured its complete separation from the retinal surface. The dye also helped to remove vitreous at the vitreous base during retinal detachment surgery. Therefore, bromophenol blue appears as a very good alternative to triamcinolone, which has been used for this purpose, because the dye has no pharmacological properties and no side effects are likely to occur such as cataract formation and increase in intraocular pressure. Further studies including larger numbers of patients are mandatory.

High-resolution retinal imaging using adaptive optics and Fourier-domain optical coherence tomography

DOEpatents

Olivier, Scot S.; Werner, John S.; Zawadzki, Robert J.; Laut, Sophie P.; Jones, Steven M.

2010-09-07

This invention permits retinal images to be acquired at high speed and with unprecedented resolution in three dimensions (4.times.4.times.6 .mu.m). The instrument achieves high lateral resolution by using adaptive optics to correct optical aberrations of the human eye in real time. High axial resolution and high speed are made possible by the use of Fourier-domain optical coherence tomography. Using this system, we have demonstrated the ability to image microscopic blood vessels and the cone photoreceptor mosaic.

[Greatness and tribulations of Zeiss and Leitz, two famous German optic companies III. Zeiss Ikon and elimination of Emanuel Goldberg].

PubMed

Gilgenkrantz, Simone

2011-05-01

Gathering archival documents to trace the history of the Zeiss company presents no difficulty : they are abundant… except for a period from 1932 to 1945, systematically ignored, and that corresponds to the Nazi period. On the website Zeiss Historica, among the outstanding personalities of the Zeiss company, we note that, for Professor Emanuel Goldberg, the web page « is still under development but an early picture of the professor is available. ». But fortunately, Mickael Buckland, a Professor at the UC Berkeley School of Information brought the life and the work of Emanuel Goldberg to light. Thanks to him, his works and innovations, who had disappeared from our cultural and scientific heritage, return to light after being erased during fifty years. Goldberg had published dozens of articles, obtained patents, developed cameras, microdots, movie cameras, and he designed what he called a "Statistical Machine ", the first electronic document retrieval machine. In France, if this rediscovery was made known to the world of information science, it has not had the impact it deserved in the scientific world. Therefore it is time to reconstruct his career and his work, and to analyse the reasons why some attempted to erase definitively his name and memory. © 2011 médecine/sciences - Inserm / SRMS.

The progress of prophylactic treatment in retinopathy of prematurity

PubMed Central

Zhang, Hong-Bing; Wang, Xiao-Dong; Xu, Kun; Li, Xiao-Gang

2018-01-01

Retinopathy of prematurity (ROP) is a retinal vascular disorder frequently found in premature infants. Different therapeutic strategies have been developed to treat ROP. However, there are still many children with ROP suffering by severe limitations in vision or even blindness. Recently, ROP has been suggested to be caused by abnormal development of the retinal vasculature, but not simply resulted by retinal neovascularization which takes about 4 to 6wk after birth in premature infants. Thus, instead of focusing on how to reduce retinal neovascularization, understanding the pathological changes and mechanisms that occur prior to retinal neovascularization is meaningful, which may lead to identify novel target(s) for the development of novel strategy to promote the healthy growth of retinal blood vessels rather than passively waiting for the appearance of retinal neovascularization and removing it by force. In this review, we discussed recent studies about, 1) the pathogenesis prior to retinal neovascularization in oxygen-induced retinopathy (OIR; a ROP in animal model) and in premature infants with ROP; 2) the preclinical and clinical research on preventive treatment of early OIR and ROP. We will not only highlight the importance of the mechanisms and signalling pathways in regulating early stage of ROP but also will provide guidance for actively exploring novel mechanisms and discovering novel treatments for early phase OIR and ROP prior to retinal neovascularization in the future. PMID:29862189

Microscope-Integrated Optical Coherence Tomography Angiography in the Operating Room in Young Children With Retinal Vascular Disease.

PubMed

Chen, Xi; Viehland, Christian; Carrasco-Zevallos, Oscar M; Keller, Brenton; Vajzovic, Lejla; Izatt, Joseph A; Toth, Cynthia A

2017-05-01

Intraoperative optical coherence tomography (OCT) has gained traction as an important adjunct for clinical decision making during vitreoretinal surgery, and OCT angiography (OCTA) has provided novel insights in clinical evaluation of retinal diseases. To date, these two technologies have not been applied in combination to evaluate retinal vascular disease in the operating suite. To conduct microscope-integrated, swept-source OCTA (MIOCTA) in children with retinal vascular disease. In this case report analysis, OCT imaging in pediatric patients, MIOCTA images were obtained during examination under anesthesia from a young boy with a history of idiopathic vitreous hemorrhage and a female infant with familial exudative vitreoretinopathy. Side-by-side comparison of research MIOCT angiograms and clinically indicated fluorescein angiograms. In 2 young children with retinal vascular disease, the MIOCTA images showed more detailed vascular patterns than were visible on the fluorescein angiograms although within a more posterior field of view. The MIOCTA system allowed visualization of small pathological retinal vessels in the retinal periphery that were obscured in the fluorescein angiograms by fluorescein staining from underlying, preexisting laser scars. This is the first report to date of the use of MIOCTA in the operating room for young children with retinal vascular disease. Further optimization of this system may allow noninvasive detailed evaluation of retinal vasculature during surgical procedures and in patients who could not cooperate with in-office examinations.

Visualization of micro-capillaries using optical coherence tomography angiography with and without adaptive optics.

PubMed

Salas, Matthias; Augustin, Marco; Ginner, Laurin; Kumar, Abhishek; Baumann, Bernhard; Leitgeb, Rainer; Drexler, Wolfgang; Prager, Sonja; Hafner, Julia; Schmidt-Erfurth, Ursula; Pircher, Michael

2017-01-01

The purpose of this work is to investigate the benefits of adaptive optics (AO) technology for optical coherence tomography angiography (OCTA). OCTA has shown great potential in non-invasively enhancing the contrast of vessels and small capillaries. Especially the capability of the technique to visualize capillaries with a lateral extension that is below the transverse resolution of the system opens unique opportunities in diagnosing retinal vascular diseases. However, there are some limitations of this technology such as shadowing and projection artifacts caused by overlying vasculature or the inability to determine the true extension of a vessel. Thus, the evaluation of the vascular structure and density based on OCTA alone can be misleading. In this paper we compare the performance of AO-OCT, AO-OCTA and OCTA for imaging retinal vasculature. The improved transverse resolution and the reduced depth of focus of AO-OCT and AO-OCTA greatly reduce shadowing artifacts allowing for a better differentiation and segmentation of different vasculature layers of the inner retina. The comparison is done on images recorded in healthy volunteers and in diabetic patients with distinct pathologies of the retinal microvasculature.

Particle swarm optimization method for small retinal vessels detection on multiresolution fundus images.

PubMed

Khomri, Bilal; Christodoulidis, Argyrios; Djerou, Leila; Babahenini, Mohamed Chaouki; Cheriet, Farida

2018-05-01

Retinal vessel segmentation plays an important role in the diagnosis of eye diseases and is considered as one of the most challenging tasks in computer-aided diagnosis (CAD) systems. The main goal of this study was to propose a method for blood-vessel segmentation that could deal with the problem of detecting vessels of varying diameters in high- and low-resolution fundus images. We proposed to use the particle swarm optimization (PSO) algorithm to improve the multiscale line detection (MSLD) method. The PSO algorithm was applied to find the best arrangement of scales in the MSLD method and to handle the problem of multiscale response recombination. The performance of the proposed method was evaluated on two low-resolution (DRIVE and STARE) and one high-resolution fundus (HRF) image datasets. The data include healthy (H) and diabetic retinopathy (DR) cases. The proposed approach improved the sensitivity rate against the MSLD by 4.7% for the DRIVE dataset and by 1.8% for the STARE dataset. For the high-resolution dataset, the proposed approach achieved 87.09% sensitivity rate, whereas the MSLD method achieves 82.58% sensitivity rate at the same specificity level. When only the smallest vessels were considered, the proposed approach improved the sensitivity rate by 11.02% and by 4.42% for the healthy and the diabetic cases, respectively. Integrating the proposed method in a comprehensive CAD system for DR screening would allow the reduction of false positives due to missed small vessels, misclassified as red lesions. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Molecular imaging reveals elevated VEGFR-2 expression in retinal capillaries in diabetes: a novel biomarker for early diagnosis

PubMed Central

Sun, Dawei; Nakao, Shintaro; Xie, Fang; Zandi, Souska; Bagheri, Abouzar; Kanavi, Mozhgan Rezaei; Samiei, Shahram; Soheili, Zahra-Soheila; Frimmel, Sonja; Zhang, Zhongyu; Ablonczy, Zsolt; Ahmadieh, Hamid; Hafezi-Moghadam, Ali

2014-01-01

Diabetic retinopathy (DR) is a microvascular complication of diabetes and a leading cause of vision loss. Biomarkers and methods for early diagnosis of DR are urgently needed. Using a new molecular imaging approach, we show up to 94% higher accumulation of custom designed imaging probes against vascular endothelial growth factor receptor 2 (VEGFR-2) in retinal and choroidal vessels of diabetic animals (P<0.01), compared to normal controls. More than 80% of the VEGFR-2 in the diabetic retina was in the capillaries, compared to 47% in normal controls (P<0.01). Angiography in rabbit retinas revealed microvascular capillaries to be the location for VEGF-A-induced leakage, as expressed by significantly higher rate of fluorophore spreading with VEGF-A injection when compared to vehicle control (26±2 vs. 3±1 μm/s, P<0.05). Immunohistochemistry showed VEGFR-2 expression in capillaries of diabetic animals but not in normal controls. Macular vessels from diabetic patients (n=7) showed significantly more VEGFR-2 compared to nondiabetic controls (n=5) or peripheral retinal regions of the same retinas (P<0.01 in both cases). Here we introduce a new approach for early diagnosis of DR and VEGFR-2 as a molecular marker. VEGFR-2 could become a key diagnostic target, one that might help to prevent retinal vascular leakage and proliferation in diabetic patients.—Sun, D., Nakao, S., Xie, F., Zandi, S., Bagheri, A., Kanavi, M. R., Samiei, S., Soheili, Z.-S., Frimmel, S., Zhang, Z., Ablonczy, Z., Ahmadieh, H., Hafezi-Moghadam, A. Molecular imaging reveals elevated VEGFR-2 expression in retinal capillaries in diabetes: a novel biomarker for early diagnosis. PMID:24903276

Retinal vessel caliber among people with acquired immunodeficiency syndrome: relationships with disease-associated factors and mortality.

PubMed

Gangaputra, Sapna; Kalyani, Partho S; Fawzi, Amani A; Van Natta, Mark L; Hubbard, Larry D; Danis, Ronald P; Thorne, Jennifer E; Holland, Gary N

2012-03-01

To evaluate relationships between retinal vessel caliber, AIDS-related factors, and mortality. Longitudinal, observational cohort study. We evaluated data for participants without ocular opportunistic infections at initial examination (baseline) in the Longitudinal Studies of the Ocular Complications of AIDS (1998-2008). Semi-automated evaluation of fundus photographs (1 eye/participant) determined central retinal artery equivalent (CRAE), central retinal vein equivalent (CRVE), and arteriole-to-venule ratio (AVR) at baseline. Multiple linear regression models, using forward selection, identified independent relationships between indices and various host- and disease-related variables. Included were 1250 participants. Mean follow-up for determination of mortality was 6.1 years. Smaller CRAE was related to increased age (P < .001) and hypertension (P < .001); larger CRAE was related to lower hematocrit (P = .002). Larger CRAE and CRVE were associated with black race (P < .001). Larger CRVE was related to smoking (P = .004); smaller CRVE was related to age (P < .001) and higher mean corpuscular volume (P = .001). We observed the following relationships with AIDS-associated factors: smaller CRAE and larger CRVE with history of highly active antiretroviral therapy (HAART; P < .001); and larger CRAE with lower CD4+ T lymphocyte count (P = .04). We did not identify independent relationships with human immunodeficiency virus RNA blood levels. There was a 12% (95% CI, 2%-21%) increase in mortality risk per quartile of decreasing AVR (P = .02). Variations in retinal vascular caliber are associated with AIDS-specific factors and are markers for increased mortality risk. Relationships are consistent with the hypothesis that the vasculature is altered by known atherogenic effects of chronic HAART or the prolonged inflammatory state associated with AIDS. Copyright © 2012 Elsevier Inc. All rights reserved.

Noninvasive Imaging of Retinal Morphology and Microvasculature in Obese Mice Using Optical Coherence Tomography and Optical Microangiography

PubMed Central

Zhi, Zhongwei; Chao, Jennifer R.; Wietecha, Tomasz; Hudkins, Kelly L.; Alpers, Charles E.; Wang, Ruikang K.

2014-01-01

Purpose. To evaluate early diabetes-induced changes in retinal thickness and microvasculature in a type 2 diabetic mouse model by using optical coherence tomography (OCT)/optical microangiography (OMAG). Methods. Twenty-two-week-old obese (OB) BTBR mice (n = 10) and wild-type (WT) control mice (n = 10) were imaged. Three-dimensional (3D) data volumes were captured with spectral domain OCT using an ultrahigh-sensitive OMAG scanning protocol for 3D volumetric angiography of the retina and dense A-scan protocol for measurement of the total retinal blood flow (RBF) rate. The thicknesses of the nerve fiber layer (NFL) and that of the NFL to the inner plexiform layer (IPL) were measured and compared between OB and WT mice. The linear capillary densities within intermediate and deep capillary layers were determined by the number of capillaries crossing a 500-μm line. The RBF rate was evaluated using an en face Doppler approach. These quantitative measurements were compared between OB and WT mice. Results. The retinal thickness of the NFL to IPL was significantly reduced in OB mice (P < 0.01) compared to that in WT mice, whereas the NFL thickness between the two was unchanged. 3D depth-resolved OMAG angiography revealed the first in vivo 3D model of mouse retinal microcirculation. Although no obvious differences in capillary vessel densities of the intermediate and deep capillary layers were detected between normal and OB mice, the total RBF rate was significantly lower (P < 0.05) in OB mice than in WT mice. Conclusions. We conclude that OB BTBR mice have significantly reduced NFL–IPL thicknesses and total RBF rates compared with those of WT mice, as imaged by OCT/OMAG. OMAG provides an unprecedented capability for high-resolution depth-resolved imaging of mouse retinal vessels and blood flow that may play a pivotal role in providing a noninvasive method for detecting early microvascular changes in patients with diabetic retinopathy. PMID:24458155

The Time Course of Deafness and Retinal Degeneration in a Kunming Mouse Model for Usher Syndrome.

PubMed

Yao, Lu; Zhang, Lei; Qi, Lin-Song; Liu, Wei; An, Jing; Wang, Bin; Xue, Jun-Hui; Zhang, Zuo-Ming

2016-01-01

Usher syndrome is a group of autosomal recessive diseases characterized by congenital deafness and retinitis pigmentosa. In a mouse model for Usher syndrome, KMush/ush, discovered in our laboratory, we measured the phenotypes, characterized the architecture and morphology of the retina, and quantified the level of expression of pde6b and ush2a between postnatal (P) days 7, and 56. Electroretinograms and auditory brainstem response were used to measure visual and auditory phenotypes. Fundus photography and light microscopy were used to measure the architecture and morphology of the retina. Quantitative real-time PCR was used to measure the expression levels of mRNA. KMush/ush mice had low amplitudes and no obvious waveforms of Electroretinograms after P14 compared with controls. Thresholds of auditory brainstem response in our model were higher than those of controls after P14. By P21, the retinal vessels of KMush/ush mice were attenuated and their optic discs had a waxy pallor. The retinas of KMush/ush mice atrophied and the choroidal vessels were clearly visible. Notably, the architecture of each retinal layer was not different as compared with control mice at P7, while the outer nuclear layer (ONL) and other retinal layers of KMush/ush mice were attenuated significantly between P14 and P21. ONL cells were barely seen in KMush/ush mice at P56. As compared with control mice, the expression of pde6b and ush2a in KMush/ush mice declined significantly after P7. This study is a first step toward characterizing the progression of disease in our mouse model. Future studies using this model may provide insights about the etiology of the disease and the relationships between genotypes and phenotypes providing a valuable resource that could contribute to the foundation of knowledge necessary to develop therapies to prevent the retinal degeneration in patients with Usher Syndrome.

N-Terminal Pro-B-Type Natriuretic Peptide Is Related to Retinal Microvascular Damage: The Rotterdam Study.

PubMed

Mutlu, Unal; Ikram, M Arfan; Hofman, Albert; de Jong, Paulus T V M; Klaver, Caroline C W; Ikram, M Kamran

2016-08-01

N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a marker of cardiac dysfunction and has been linked to various indices of large vessel disease. However, it remains unclear whether NT-proBNP also relates to microvascular damage. In a community-dwelling population, we studied the association between NT-proBNP and retinal microvascular damage. From the population-based Rotterdam Study, we included 8437 participants (mean age 64.1 years and 59% women) without a history of cardiovascular disease, with NT-proBNP data and gradable retinal images. NT-proBNP serum levels were measured using an immunoassay. Retinopathy signs, that is, exudates, microaneurysms, cotton wool spots, and dot/blot hemorrhages, present on fundus photographs were graded in the total study population; retinal vascular calibers, that is, arteriolar and venular calibers, were semiautomatically measured in a subsample (n=2763) of the study population. We conducted cross-sectional analyses on the association between NT-proBNP and retinal microvascular damage using logistic and linear regression models, adjusting for age, sex, and cardiovascular risk factors. We found that NT-proBNP was associated with the presence of retinopathy (adjusted odds ratio [95% confidence interval] per SD increase in natural log-transformed NT-proBNP: 1.14 [1.03-1.27]). We also found that higher NT-proBNP was associated with narrower arteriolar calibers (adjusted mean difference in arteriolar caliber per SD increase in natural log-transformed NT-proBNP: -0.89 µm [-1.54 to -0.24]). This association remained unchanged after excluding participants with retinopathy signs. In participants free of clinical cardiovascular disease, higher levels of NT-proBNP are associated with retinal microvascular damage, suggesting a potential role for NT-proBNP as marker for small vessel disease. © 2016 American Heart Association, Inc.

Angiography reveals novel features of the retinal vasculature in healthy and diabetic mice.

PubMed

McLenachan, Samuel; Magno, Aaron Len; Ramos, David; Catita, Joana; McMenamin, Paul G; Chen, Fred Kuanfu; Rakoczy, Elizabeth Piroska; Ruberte, Jesus

2015-09-01

The mouse retina is a commonly used animal model for the study of pathogenesis and treatment of blinding retinal vascular diseases such as diabetic retinopathy. In this study, we aimed to characterize normal and pathological variations in vascular anatomy in the mouse retina using fluorescein angiography visualized with scanning laser ophthalmoscopy and optical coherence tomography (SLO-OCT). We examined eyes from C57BL/6J wild type mice as well as the Ins2(Akita) and Akimba mouse models of diabetic retinopathy using the Heidelberg Retinal Angiography (HRA) and OCT system. Angiography was performed on three focal planes to examine distinct vascular layers. For comparison with angiographic data, ex vivo analyses, including Indian ink angiography, histology and 3D confocal scanning laser microscopy were performed in parallel. All layers of the mouse retinal vasculature could be readily visualized during fluorescein angiography by SLO-OCT. Blood vessel density was increased in the deep vascular plexus (DVP) compared with the superficial vascular plexus (SVP). Arteriolar and venular typologies were established and structural differences were observed between venular types. Unexpectedly, the hyaloid artery was found to persist in 15% of C57BL/6 mice, forming anastomoses with peripheral retinal capillaries. Fluorescein leakage was easily detected in Akimba retinae by angiography, but was not observed in Ins2(Akita) mice. Blood vessel density was increased in the DVP of 6 month old Ins2(Akita) mice, while the SVP displayed reduced branching in precapillary arterioles. In summary, we present the first comprehensive characterization of the mouse retinal vasculature by SLO-OCT fluorescein angiography. Using this clinical imaging technique, we report previously unrecognized variations in C57BL/6J vascular anatomy and novel features of vascular retinopathy in the Ins2(Akita) mouse model of diabetes. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Retinal vessel diameter and estimated cerebrospinal fluid pressure in arterial hypertension: the Beijing Eye Study.

PubMed

Jonas, Jost B; Wang, Ningli; Wang, Shuang; Wang, Ya Xing; You, Qi Sheng; Yang, Diya; Wei, Wen Bin; Xu, Liang

2014-09-01

Hypertensive retinal microvascular abnormalities include an increased retinal vein-to-artery diameter ratio. Because central retinal vein pressure depends on cerebrospinal fluid pressure (CSFP), we examined whether the retinal vein-to-artery diameter ratio and other retinal hypertensive signs are associated with CSFP. Participants of the population-based Beijing Eye Study (n = 1,574 subjects) underwent measurement of the temporal inferior and superior retinal artery and vein diameter. CSFP was calculated as 0.44 × body mass index (kg/m(2)) + 0.16 × diastolic blood pressure (mm Hg) - 0.18 × age (years) - 1.91. Larger retinal vein diameters and higher vein-to-artery diameter ratios were significantly associated with higher estimated CSFP (P = 0.001) in multivariable analysis. In contrast, temporal inferior retinal arterial diameter was marginally associated (P = 0.03) with estimated CSFP, and temporal superior artery diameter was not significantly associated (P = 0.10) with estimated CSFP; other microvascular abnormalities, such as arteriovenous crossing signs, were also not significantly associated with estimated CSFP. In a reverse manner, higher estimated CSFP as a dependent variable in the multivariable analysis was associated with wider retinal veins and higher vein-to-artery diameter ratio. In the same model, estimated CSFP was not significantly correlated with retinal artery diameters or other retinal microvascular abnormalities. Correspondingly, arterial hypertension was associated with retinal microvascular abnormalities such as arteriovenous crossing signs (P = 0.003), thinner temporal retinal arteries (P < 0.001), higher CSFP (P < 0.001), and wider retinal veins (P = 0.001) or, as a corollary, with a higher vein-to-artery diameter ratio in multivariable analysis. Wider retinal vein diameters are associated with higher estimated CSFP and vice versa. In arterial hypertension, an increased retinal vein-to-artery diameter ratio depends on elevated CSFP, which is correlated with blood pressure. © American Journal of Hypertension, Ltd 2014. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Improving the blind restoration of retinal images by means of point-spread-function estimation assessment

NASA Astrophysics Data System (ADS)

Marrugo, Andrés. G.; Millán, María. S.; Å orel, Michal; Kotera, Jan; Å roubek, Filip

2015-01-01

Retinal images often suffer from blurring which hinders disease diagnosis and progression assessment. The restoration of the images is carried out by means of blind deconvolution, but the success of the restoration depends on the correct estimation of the point-spread-function (PSF) that blurred the image. The restoration can be space-invariant or space-variant. Because a retinal image has regions without texture or sharp edges, the blind PSF estimation may fail. In this paper we propose a strategy for the correct assessment of PSF estimation in retinal images for restoration by means of space-invariant or space-invariant blind deconvolution. Our method is based on a decomposition in Zernike coefficients of the estimated PSFs to identify valid PSFs. This significantly improves the quality of the image restoration revealed by the increased visibility of small details like small blood vessels and by the lack of restoration artifacts.

The application of retinal fundus camera imaging in dementia: A systematic review.

PubMed

McGrory, Sarah; Cameron, James R; Pellegrini, Enrico; Warren, Claire; Doubal, Fergus N; Deary, Ian J; Dhillon, Baljean; Wardlaw, Joanna M; Trucco, Emanuele; MacGillivray, Thomas J

2017-01-01

The ease of imaging the retinal vasculature, and the evolving evidence suggesting this microvascular bed might reflect the cerebral microvasculature, presents an opportunity to investigate cerebrovascular disease and the contribution of microvascular disease to dementia with fundus camera imaging. A systematic review and meta-analysis was carried out to assess the measurement of retinal properties in dementia using fundus imaging. Ten studies assessing retinal properties in dementia were included. Quantitative measurement revealed significant yet inconsistent pathologic changes in vessel caliber, tortuosity, and fractal dimension. Retinopathy was more prevalent in dementia. No association of age-related macular degeneration with dementia was reported. Inconsistent findings across studies provide tentative support for the application of fundus camera imaging as a means of identifying changes associated with dementia. The potential of fundus image analysis in differentiating between dementia subtypes should be investigated using larger well-characterized samples. Future work should focus on refining and standardizing methods and measurements.

Integrated photoacoustic microscopy, optical coherence tomography, and fluorescence microscopy for multimodal chorioretinal imaging

NASA Astrophysics Data System (ADS)

Tian, Chao; Zhang, Wei; Nguyen, Van Phuc; Huang, Ziyi; Wang, Xueding; Paulus, Yannis M.

2018-02-01

Current clinical available retinal imaging techniques have limitations, including limited depth of penetration or requirement for the invasive injection of exogenous contrast agents. Here, we developed a novel multimodal imaging system for high-speed, high-resolution retinal imaging of larger animals, such as rabbits. The system integrates three state-of-the-art imaging modalities, including photoacoustic microscopy (PAM), optical coherence tomography (OCT), and fluorescence microscopy (FM). In vivo experimental results of rabbit eyes show that the PAM is able to visualize laser-induced retinal burns and distinguish individual eye blood vessels using a laser exposure dose of 80 nJ, which is well below the American National Standards Institute (ANSI) safety limit 160 nJ. The OCT can discern different retinal layers and visualize laser burns and choroidal detachments. The novel multi-modal imaging platform holds great promise in ophthalmic imaging.

Reproducibility of peripapillary retinal nerve fiber layer thickness with spectral domain cirrus high-definition optical coherence tomography in normal eyes.

PubMed

Hong, Samin; Kim, Chan Yun; Lee, Won Seok; Seong, Gong Je

2010-01-01

To assess the reproducibility of the new spectral domain Cirrus high-definition optical coherence tomography (HD-OCT; Carl Zeiss Meditec, Dublin, CA, USA) for analysis of peripapillary retinal nerve fiber layer (RNFL) thickness in healthy eyes. Thirty healthy Korean volunteers were enrolled. Three optic disc cube 200 x 200 Cirrus HD-OCT scans were taken on the same day in discontinuous sessions by the same operator without using the repeat scan function. The reproducibility of the calculated RNFL thickness and probability code were determined by the intraclass correlation coefficient (ICC), coefficient of variation (CV), test-retest variability, and Fleiss' generalized kappa (kappa). Thirty-six eyes were analyzed. For average RNFL thickness, the ICC was 0.970, CV was 2.38%, and test-retest variability was 4.5 microm. For all quadrants except the nasal, ICCs were 0.972 or higher and CVs were 4.26% or less. Overall test-retest variability ranged from 5.8 to 8.1 microm. The kappa value of probability codes for average RNFL thickness was 0.690. The kappa values of quadrants and clock-hour sectors were lower in the nasal areas than in other areas. The reproducibility of Cirrus HD-OCT to analyze peripapillary RNFL thickness in healthy eyes was excellent compared with the previous reports for time domain Stratus OCT. For the calculated RNFL thickness and probability code, variability was relatively higher in the nasal area, and more careful analyses are needed.

[Role of VEGF in diseases of the retina].

PubMed

Barquet, Luis Arias

2015-03-01

Angiogenesis is the process through which new blood vessels are formed, based on preexisting vessels, and is the paradigm of diseases such as cancer and exudative ageassociated macular degeneration (ARMD). Several proangiogenic factors have been identified, such as vascular endothelial growth factor (VEGF), especially VEGF-A, which activates endothelial cells and promotes cell proliferation, migration, and an increase in vascular permeability. VEGF is also involved in the etiopathogenesis of other retinal diseases, such as diabetic macular edema and macular edema secondary to retinal vein occlusion. Likewise, there is increasing evidence that placental growth factor (PIGF) acts recepsynergetically with VEGF in promoting these diseases. Currently, the main treatment for these diseases are the anti-VEGF drugs, aflibercept, ranibizumab and bevacizumab. These agents differ in their molecular structure and mechanism of action. Copyright © 2015 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

Reliability of Using Retinal Vascular Fractal Dimension as a Biomarker in the Diabetic Retinopathy Detection

PubMed Central

Zhang, Jiong; Bekkers, Erik; Abbasi-Sureshjani, Samaneh

2016-01-01

The retinal fractal dimension (FD) is a measure of vasculature branching pattern complexity. FD has been considered as a potential biomarker for the detection of several diseases like diabetes and hypertension. However, conflicting findings were found in the reported literature regarding the association between this biomarker and diseases. In this paper, we examine the stability of the FD measurement with respect to (1) different vessel annotations obtained from human observers, (2) automatic segmentation methods, (3) various regions of interest, (4) accuracy of vessel segmentation methods, and (5) different imaging modalities. Our results demonstrate that the relative errors for the measurement of FD are significant and FD varies considerably according to the image quality, modality, and the technique used for measuring it. Automated and semiautomated methods for the measurement of FD are not stable enough, which makes FD a deceptive biomarker in quantitative clinical applications. PMID:27703803

Reliability of Using Retinal Vascular Fractal Dimension as a Biomarker in the Diabetic Retinopathy Detection.

PubMed

Huang, Fan; Dashtbozorg, Behdad; Zhang, Jiong; Bekkers, Erik; Abbasi-Sureshjani, Samaneh; Berendschot, Tos T J M; Ter Haar Romeny, Bart M

2016-01-01

The retinal fractal dimension (FD) is a measure of vasculature branching pattern complexity. FD has been considered as a potential biomarker for the detection of several diseases like diabetes and hypertension. However, conflicting findings were found in the reported literature regarding the association between this biomarker and diseases. In this paper, we examine the stability of the FD measurement with respect to (1) different vessel annotations obtained from human observers, (2) automatic segmentation methods, (3) various regions of interest, (4) accuracy of vessel segmentation methods, and (5) different imaging modalities. Our results demonstrate that the relative errors for the measurement of FD are significant and FD varies considerably according to the image quality, modality, and the technique used for measuring it. Automated and semiautomated methods for the measurement of FD are not stable enough, which makes FD a deceptive biomarker in quantitative clinical applications.

Automated detection of red lesions from digital colour fundus photographs.

PubMed

Jaafar, Hussain F; Nandi, Asoke K; Al-Nuaimy, Waleed

2011-01-01

Earliest signs of diabetic retinopathy, the major cause of vision loss, are damage to the blood vessels and the formation of lesions in the retina. Early detection of diabetic retinopathy is essential for the prevention of blindness. In this paper we present a computer-aided system to automatically identify red lesions from retinal fundus photographs. After pre-processing, a morphological technique was used to segment red lesion candidates from the background and other retinal structures. Then a rule-based classifier was used to discriminate actual red lesions from artifacts. A novel method for blood vessel detection is also proposed to refine the detection of red lesions. For a standarised test set of 219 images, the proposed method can detect red lesions with a sensitivity of 89.7% and a specificity of 98.6% (at lesion level). The performance of the proposed method shows considerable promise for detection of red lesions as well as other types of lesions.

ERK1/2/COX-2/PGE2 signaling pathway mediates GPR91-dependent VEGF release in streptozotocin-induced diabetes

PubMed Central

Li, Tingting; Hu, Jianyan; Du, Shanshan; Chen, Yongdong; Wang, Shuai

2014-01-01

Purpose Retinal vascular dysfunction caused by vascular endothelial growth factor (VEGF) is the major pathological change that occurs in diabetic retinopathy (DR). It has recently been demonstrated that G protein-coupled receptor 91 (GPR91) plays a major role in both vasculature development and retinal angiogenesis. In this study, we examined the signaling pathways involved in GPR91-dependent VEGF release during the early stages of retinal vascular change in streptozotocin-induced diabetes. Methods Diabetic rats were assigned randomly to receive intravitreal injections of shRNA lentiviral particles targeting GPR91 (LV.shGPR91) or control particles (LV.shScrambled). Accumulation of succinate was assessed by gas chromatography-mass spectrometry (GC-MS). At 14 weeks, the ultrastructure and function of the retinal vessels of diabetic retinas with or without shRNA treatment were assessed using hematoxylin and eosin (HE) staining, transmission electron microscopy (TEM), and Evans blue dye permeability. The expression of GPR91, extracellular signal-regulated kinases 1 and 2 (ERK1/2) and cyclooxygenase-2 (COX-2) were measured using immunofluorescence and western blotting. COX-2 and VEGF mRNA were determined by quantitative RT–PCR. Prostaglandin E2 (PGE2) and VEGF secretion were detected using an enzyme-linked immunosorbent assay. Results Succinate exhibited abundant accumulation in diabetic rat retinas. The retinal telangiectatic vessels, basement membrane thickness, and Evans blue dye permeability were attenuated by treatment with GPR91 shRNA. In diabetic rats, knockdown of GPR91 inhibited the activities of ERK1/2 and COX-2 as well as the expression of PGE2 and VEGF. Meanwhile, COX-2, PGE2, and VEGF expression was inhibited by ERK1/2 inhibitor U0126 and COX-2 inhibitor NS-398. Conclusions Our data suggest that hyperglycemia causes succinate accumulation and GPR91 activity in retinal ganglion cells, which mediate VEGF-induced retinal vascular change via the ERK1/2/COX-2/PGE2 pathway. This study highlights the signaling pathway as a potential target for intervention in DR. PMID:25324681

The TetO rat as a new translational model for type 2 diabetic retinopathy by inducible insulin receptor knockdown.

PubMed

Reichhart, Nadine; Crespo-Garcia, Sergio; Haase, Nadine; Golic, Michaela; Skosyrski, Sergej; Rübsam, Anne; Herrspiegel, Christina; Kociok, Norbert; Alenina, Natalia; Bader, Michael; Dechend, Ralf; Strauss, Olaf; Joussen, Antonia M

2017-01-01

Although the renin-angiotensin system plays an important role in the progression of diabetic retinopathy, its influence therein has not been systematically evaluated. Here we test the suitability of a new translational model of diabetic retinopathy, the TetO rat, for addressing the role of angiotensin-II receptor 1 (AT1) blockade in experimental diabetic retinopathy. Diabetes was induced by tetracycline-inducible small hairpin RNA (shRNA) knockdown of the insulin receptor in rats, generating TetO rats. Systemic treatment consisted of an AT1 blocker (ARB) at the onset of diabetes, following which, 4-5 weeks later the retina was analysed in vivo and ex vivo. Retinal function was assessed by Ganzfeld electroretinography (ERG). Retinal vessels in TetO rats showed differences in vessel calibre, together with gliosis. The total number and the proportion of activated mononuclear phagocytes was increased. TetO rats presented with loss of retinal ganglion cells (RGC) and ERG indicated photoreceptor malfunction. Both the inner and outer blood-retina barriers were affected. The ARB treated group showed reduced gliosis and an overall amelioration of retinal function, alongside RGC recovery, whilst no statistically significant differences in vascular and inflammatory features were detected. The TetO rat represents a promising translational model for the early neurovascular changes associated with type 2 diabetic retinopathy. ARB treatment had an effect on the neuronal component of the retina but not on the vasculature.

Comprehensive automatic assessment of retinal vascular abnormalities for computer-assisted retinopathy grading.

PubMed

Joshi, Vinayak; Agurto, Carla; VanNess, Richard; Nemeth, Sheila; Soliz, Peter; Barriga, Simon

2014-01-01

One of the most important signs of systemic disease that presents on the retina is vascular abnormalities such as in hypertensive retinopathy. Manual analysis of fundus images by human readers is qualitative and lacks in accuracy, consistency and repeatability. Present semi-automatic methods for vascular evaluation are reported to increase accuracy and reduce reader variability, but require extensive reader interaction; thus limiting the software-aided efficiency. Automation thus holds a twofold promise. First, decrease variability while increasing accuracy, and second, increasing the efficiency. In this paper we propose fully automated software as a second reader system for comprehensive assessment of retinal vasculature; which aids the readers in the quantitative characterization of vessel abnormalities in fundus images. This system provides the reader with objective measures of vascular morphology such as tortuosity, branching angles, as well as highlights of areas with abnormalities such as artery-venous nicking, copper and silver wiring, and retinal emboli; in order for the reader to make a final screening decision. To test the efficacy of our system, we evaluated the change in performance of a newly certified retinal reader when grading a set of 40 color fundus images with and without the assistance of the software. The results demonstrated an improvement in reader's performance with the software assistance, in terms of accuracy of detection of vessel abnormalities, determination of retinopathy, and reading time. This system enables the reader in making computer-assisted vasculature assessment with high accuracy and consistency, at a reduced reading time.

Applying photoacoustics to quantification of melanin concentration in retinal pigment epithelium (Conference Presentation)

NASA Astrophysics Data System (ADS)

Shu, Xiao; Zhang, Hao F.; Liu, Wenzhong

2016-03-01

The melanin in the retinal pigment epithelium (RPE) protects retina and other ocular tissues by photo-screening and acting as antioxidant and free radical scavenger. It helps maintain normal visual functions since human eye is subjected to lifelong high oxygen stress and photon exposure. Loss of the RPE melanin weakens the protection mechanism and jeopardizes ocular health. Local decrease in the RPE melanin concentration is believed to be both a cause and a sign of early-stage age-related macular degeneration (AMD), the leading blinding disease in developed world. Current technology cannot quantitatively measure the RPE melanin concentration which might be a promising marker in early AMD screening. Photoacoustic ophthalmoscopy (PAOM), as an emerging optical absorption-based imaging technology, can potentially be applied to measure the RPE melanin concentration if the dependence of the detectable photoacoustic (PA) signal amplitudes on the RPE melanin concentrations is verified. In this study, we tested the feasibility of using PA signal ratio from RPE melanin and the nearby retinal blood vessels as an indicator of the RPE melanin variation. A novel whole eye optical model was designed and Monte Carlo modeling of light (MCML) was employed. We examined the influences on quantification from PAOM axial resolution, the depth and diameter of the retinal blood vessel, and the RPE thickness. The results show that the scheme is robust to individual histological and illumination variations. This study suggests that PAOM is capable of quantitatively measuring the RPE melanin concentration in vivo.

Retinal and choroidal imaging in vivo using integrated photoacoustic microscopy and optical coherence tomography

NASA Astrophysics Data System (ADS)

Tian, Chao; Zhang, Wei; Nguyen, Van Phuc; Huang, Ziyi; Wang, Xueding; Paulus, Yannis M.

2018-02-01

Most reported photoacoustic ocular imaging work to date uses small animals, such as mice and rats, the eyes of which are small and less than one-third the size of a human eye, which poses a challenge for clinical translation. Here we achieved chorioretinal imaging of larger animals, i.e. rabbits, using a dual-modality photoacoustic microscopy (PAM) and optical coherence tomography (OCT) system. Preliminary experimental results in living rabbits demonstrate that the PAM can noninvasively visualize depth-resolved retinal and choroidal vessels using a safe laser exposure dose; and the OCT can finely distinguish different retinal layers, the choroid, and the sclera. This reported work might be a major step forward in clinical translation of photoacoustic microscopy.

Dark adaptation during systemic hypoxia induced by chronic respiratory insufficiency.

PubMed

Thylefors, Joakim; Piitulainen, Eeva; Havelius, Ulf

2009-03-01

To investigate dark adaptation during hypoxia in patients with chronic respiratory failure. At three visits, dark adaptation was recorded by computerized dark adaptometry in 13 patients with chronic respiratory insufficiency treated by long-term oxygen therapy. At visits 1 and 3, the patients were administered their usual oxygen supplement. At visit 2, no oxygen was given. At each visit, an analysis of arterial blood gases measured pH, partial pressure of O(2) (Pao(2)), partial pressure of CO(2) (Paco(2)), base excess (BE), standard bicarbonate (HCO(3)), and arterial oxygen saturation. Pulse oximetry (POX) was also recorded. Significant differences were recorded between visits 1 and 2 and between visits 2 and 3 for Pao(2), arterial oxygen saturation, and POX; no differences were found for pH, Paco(2), BE, or HCO(3). No differences were seen between visits 1 and 3 for any of the laboratory parameters. All patients had normal and unchanged dark adaptation at the three visits. Hypoxia in chronic respiratory insufficiency was associated with normal dark adaptation, in contrast to hypoxia in healthy persons at high altitudes, which is known to produce impaired dark adaptation. The result may partly reflect the influence of Paco(2) on the lumen of choroidal and retinal vessels. At high altitudes, with hypocapnic vasoconstriction the oxygen supply to the retina is further compromised, resulting in reduced dark adaptation. The authors hypothesize that respiratory insufficiency with hypercapnia or normocapnia will have larger choroidal and retinal vessel lumens, added to by further dilation of retinal vessels during hypoxia. The tentative net effect would be preserved dark adaptation.

Repair of Total Tractional Retinal Detachment in Norrie Disease: Report of Technique and Successful Surgical Outcome.

PubMed

Todorich, Bozho; Thanos, Aristomenis; Yonekawa, Yoshihiro; Capone, Antonio

2017-03-01

Norrie disease is a rare, but devastating cause of pediatric retinal detachment, universally portending a poor visual prognosis. This paper describes successful surgical management of an infant with total retinal detachment associated with Norrie disease mutation. The infant was a full-term white male who presented with bilateral total funnel retinal detachments (RDs). He underwent genetic testing, which demonstrated single-point mutation 133 G>A transition in exon 2 of the NDP gene. The retinal detachment was managed with translimbal iridectomy, lensectomy, capsulectomy, and vitrectomy. Careful dissection of the retrolental membranes resulted in opening of the funnel. Single-stage surgery in this child's eye achieved re-attachment of the posterior pole with progressive reabsorption of subretinal fluid and cholesterol without the need for external drainage. Fluorescein angiography, performed at 2 months postoperatively, demonstrated perfusion of major vascular arcades, but with significant abnormalities and aneurysmal changes of higher-order vessels, suggestive of retinal and vascular dysplasia. The child has maintained brisk light perception vision. Early surgical intervention with careful dissection of tractional tissues can potentially result in good anatomic outcomes in some patients with Norrie disease-associated retinal detachment. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:260-262.]. Copyright 2017, SLACK Incorporated.

The spectrum of retinopathy in adults with Plasmodium falciparum malaria.

PubMed

Maude, Richard J; Beare, Nicholas A V; Abu Sayeed, Abdullah; Chang, Christina C; Charunwatthana, Prakaykaew; Faiz, M Abul; Hossain, Amir; Yunus, Emran Bin; Hoque, M Gofranul; Hasan, Mahtab Uddin; White, Nicholas J; Day, Nicholas P J; Dondorp, Arjen M

2009-07-01

A specific retinopathy has been described in African children with cerebral malaria, but in adults this has not been extensively studied. Since the structure and function of the retinal vasculature greatly resembles the cerebral vasculature, study of retinal changes can reveal insights into the pathophysiology of cerebral malaria. A detailed observational study of malarial retinopathy in Bangladeshi adults was performed using high-definition portable retinal photography. Retinopathy was present in 17/27 adults (63%) with severe malaria and 14/20 adults (70%) with cerebral malaria. Moderate or severe retinopathy was more frequent in cerebral malaria (11/20, 55%) than in uncomplicated malaria (3/15, 20%; P=0.039), bacterial sepsis (0/5, 0%; P=0.038) or healthy controls (0/18, 0%; P<0.001). The spectrum of malarial retinopathy was similar to that previously described in African children, but no vessel discolouration was observed. The severity of retinal whitening correlated with admission venous plasma lactate (P=0.046), suggesting that retinal ischaemia represents systemic ischaemia. In conclusion, retinal changes related to microvascular obstruction were common in adults with severe falciparum malaria and correlated with disease severity and coma, suggesting that a compromised microcirculation has important pathophysiological significance in severe and cerebral malaria. Portable retinal photography has potential as a valuable tool to study malarial retinopathy.

Creating a Literate Society: College-Business-Community Partnerships.

ERIC Educational Resources Information Center

Zeiss, Tony, Ed.

Brief descriptions are provided of 16 model literacy initiatives undertaken by community colleges in conjunction with local businesses or community groups. Following introductory comments by Barbara Bush, Tony Zeiss, H. James Owen, and Roy Romer, "Literacy: America's Great Deficit," by Earnestine Thomas-Wilson-Robertson and Tony Zeiss, reviews…

Improvement of horizontal macular contraction after surgical removal of epiretinal membranes.

PubMed

Yang, H K; Kim, S J; Jung, Y S; Kim, K G; Kim, J H; Yu, H G

2011-06-01

To determine whether horizontal macular contraction caused by epiretinal membranes (ERMs) improves after surgical removal. In this prospective, single-center, observational study, 63 consecutive patients with unilateral idiopathic ERM in one eye and no retinal disease in the fellow eye underwent pars plana vitrectomy. Fundus photography and optical coherence tomography (OCT) were performed preoperatively and at 3 months postoperatively. The area enclosed by superior and inferior major vessels from the optic disc to the fovea (area under major vessel (AUV)) and the macroscopic diverging angle (MDA) between superior and inferior major vessels were calculated using digital image analysis of fundus photographs and compared pre- and postoperatively. AUV was significantly smaller in the eyes with ERM compared with the normal fellow eyes (P<0.001). Significant postoperative change in AUV and MDA was demonstrated after ERM removal (P<0.001). However, postoperative AUV of grade 2 and 3 ERM eyes was still significantly smaller than that of normal fellow eyes. Macular thickness differences measured with stratus OCT were positively correlated with AUV differences. Retinal topographic changes caused by ERM improved in part after ERM removal. The improvement of topographic changes were correlated with tomographic changes detected with OCT.

Retinal vessel segmentation using the 2-D Gabor wavelet and supervised classification.

PubMed

Soares, João V B; Leandro, Jorge J G; Cesar Júnior, Roberto M; Jelinek, Herbert F; Cree, Michael J

2006-09-01

We present a method for automated segmentation of the vasculature in retinal images. The method produces segmentations by classifying each image pixel as vessel or nonvessel, based on the pixel's feature vector. Feature vectors are composed of the pixel's intensity and two-dimensional Gabor wavelet transform responses taken at multiple scales. The Gabor wavelet is capable of tuning to specific frequencies, thus allowing noise filtering and vessel enhancement in a single step. We use a Bayesian classifier with class-conditional probability density functions (likelihoods) described as Gaussian mixtures, yielding a fast classification, while being able to model complex decision surfaces. The probability distributions are estimated based on a training set of labeled pixels obtained from manual segmentations. The method's performance is evaluated on publicly available DRIVE (Staal et al., 2004) and STARE (Hoover et al., 2000) databases of manually labeled images. On the DRIVE database, it achieves an area under the receiver operating characteristic curve of 0.9614, being slightly superior than that presented by state-of-the-art approaches. We are making our implementation available as open source MATLAB scripts for researchers interested in implementation details, evaluation, or development of methods.

[Hemodynamic phenomena in retrobulhar and eyeball vessels].

PubMed

Modrzejewska, Monika

2011-01-01

The purpose of this review was to evaluate factors connected with blood flow and indices regulating vascular diameter and some parameters influencing retrobulbar circulation such as type of vascular resistance, anatomical structure of vascular wall and vessel lumen. Neurogenic and angiogenic factors, rheological blood composition, presence of anatomical and pathological obstructions on blood flow pathway as well as degree of development of collateral circulation pathways--have influence on the volume and blood flow velocity in eyeball. There were discussed bulbar circulation hemodynamics, emphasizing the importance of perfusion pressure. The role of risk factors was underlined for pathological lesions in vessels supplying blood to eyeball and in ophthalmic artery (OA) and its collaterals, in central retinal artery (CRA) as well as posterior ciliary arteries (PCAs), and in venous system carrying away blood from eye. IN CONCLUSION--the results of many studies of retrobulbar blood flow in different types of ophthalmic diseases of the vascular etiopathogenesis indicate that registry of the mean values of blood flow parameters and vascular resistance indices parallel to measurement of blood flow spectrum in OA, CRA, PCAs arteries, might contribute much information to explain or to evaluate nature of pathological changes in retinal and choroidal circulation.

A peptide inhibitor of the urokinase/urokinase receptor system inhibits alteration of the blood-retinal barrier in diabetes.

PubMed

Navaratna, Deepti; Menicucci, Gina; Maestas, Joann; Srinivasan, Ramprasad; McGuire, Paul; Das, Arup

2008-09-01

One of the major complications of diabetes is the alteration of the blood-retinal barrier, leading to retinal edema and consequent vision loss. The aim of this study was to evaluate the role of the urokinase plasminogen activator (uPA)/uPA receptor (uPAR) system in the regulation of retinal vascular permeability. Biochemical, molecular, and histological techniques were used to examine the role of uPA and uPAR in the regulation of retinal vascular permeability in diabetic rats and cultured retinal endothelial cells. The increased retinal vascular permeability in diabetic rats was associated with a decrease in vascular endothelial (VE) -cadherin expression in retinal vessels. Treatment with the uPA/uPAR-inhibiting peptide (A6) was shown to reduce diabetes-induced permeability and the loss of VE-cadherin. The increased permeability of cultured cells in response to advanced glycation end products (AGEs) was significantly inhibited with A6. Treatment of endothelial cells with specific matrix metalloproteinases or AGEs resulted in loss of VE-cadherin from the cell surface, which could be inhibited by A6. uPA/uPAR physically interacts with AGEs/receptor for advanced glycation end products on the cell surface and regulates its activity. uPA and its receptor uPAR play important roles in the alteration of the blood-retinal barrier through proteolytic degradation of VE-cadherin. The ability of A6 to block retinal vascular permeability in diabetes suggests a potential therapeutic approach for the treatment of diabetic macular edema.

Real-time blind deconvolution of retinal images in adaptive optics scanning laser ophthalmoscopy

NASA Astrophysics Data System (ADS)

Li, Hao; Lu, Jing; Shi, Guohua; Zhang, Yudong

2011-06-01

With the use of adaptive optics (AO), the ocular aberrations can be compensated to get high-resolution image of living human retina. However, the wavefront correction is not perfect due to the wavefront measure error and hardware restrictions. Thus, it is necessary to use a deconvolution algorithm to recover the retinal images. In this paper, a blind deconvolution technique called Incremental Wiener filter is used to restore the adaptive optics confocal scanning laser ophthalmoscope (AOSLO) images. The point-spread function (PSF) measured by wavefront sensor is only used as an initial value of our algorithm. We also realize the Incremental Wiener filter on graphics processing unit (GPU) in real-time. When the image size is 512 × 480 pixels, six iterations of our algorithm only spend about 10 ms. Retinal blood vessels as well as cells in retinal images are restored by our algorithm, and the PSFs are also revised. Retinal images with and without adaptive optics are both restored. The results show that Incremental Wiener filter reduces the noises and improve the image quality.

Detection of retinal nerve fiber layer defects on retinal fundus images for early diagnosis of glaucoma

NASA Astrophysics Data System (ADS)

Muramatsu, Chisako; Hayashi, Yoshinori; Sawada, Akira; Hatanaka, Yuji; Hara, Takeshi; Yamamoto, Tetsuya; Fujita, Hiroshi

2010-01-01

Retinal nerve fiber layer defect (NFLD) is a major sign of glaucoma, which is the second leading cause of blindness in the world. Early detection of NFLDs is critical for improved prognosis of this progressive, blinding disease. We have investigated a computerized scheme for detection of NFLDs on retinal fundus images. In this study, 162 images, including 81 images with 99 NFLDs, were used. After major blood vessels were removed, the images were transformed so that the curved paths of retinal nerves become approximately straight on the basis of ellipses, and the Gabor filters were applied for enhancement of NFLDs. Bandlike regions darker than the surrounding pixels were detected as candidates of NFLDs. For each candidate, image features were determined and the likelihood of a true NFLD was determined by using the linear discriminant analysis and an artificial neural network (ANN). The sensitivity for detecting the NFLDs was 91% at 1.0 false positive per image by using the ANN. The proposed computerized system for the detection of NFLDs can be useful to physicians in the diagnosis of glaucoma in a mass screening.

Estimating retinal vascular permeability using the adiabatic approximation to the tissue homogeneity model with fluorescein videoangiography

NASA Astrophysics Data System (ADS)

Tichauer, Kenneth M.; Osswald, Christian R.; Dosmar, Emily; Guthrie, Micah J.; Hones, Logan; Sinha, Lagnojita; Xu, Xiaochun; Mieler, William F.; St. Lawrence, Keith; Kang-Mieler, Jennifer J.

2015-06-01

Clinical symptoms of diabetic retinopathy are not detectable until damage to the retina reaches an irreversible stage, at least by today's treatment standards. As a result, there is a push to develop new, "sub-clinical" methods of predicting the onset of diabetic retinopathy before the onset of irreversible damage. With diabetic retinopathy being associated with the accumulation of long-term mild damage to the retinal vasculature, retinal blood vessel permeability has been proposed as a key parameter for detecting preclinical stages of retinopathy. In this study, a kinetic modeling approach used to quantify vascular permeability in dynamic contrast-enhanced medical imaging was evaluated in noise simulations and then applied to retinal videoangiography data in a diabetic rat for the first time to determine the potential for this approach to be employed clinically as an early indicator of diabetic retinopathy. Experimental levels of noise were found to introduce errors of less than 15% in estimates of blood flow and extraction fraction (a marker of vascular permeability), and fitting of rat retinal fluorescein angiography data provided stable maps of both parameters.

THE SECOND BLIND SPOT: SMALL RETINAL VESSEL VASCULOPATHY AFTER VACCINATION AGAINST NEISSERIA MENINGITIDIS AND YELLOW FEVER.

PubMed

Moysidis, Stavros N; Koulisis, Nicole; Patel, Vivek R; Kashani, Amir H; Rao, Narsing A; Humayun, Mark S; Rodger, Damien C

2017-01-01

To describe a case of small retinal vessel vasculopathy postvaccination. We report the case of a 41-year-old white man who presented with a "second blind spot," describing a nasal scotoma in the right eye that started 4 days after vaccinations against Neisseria meningitidis and the yellow fever virus, and after a 2-month period of high stress and decreased sleep. Clinical examination, Humphrey visual field testing, and multimodal imaging with fundus photographs, autofluorescence, fluorescein angiography, and spectral domain optical coherence tomography and angiography were performed. Clinical examination revealed a well-circumscribed, triangular area of retinal graying of about 1-disk diameter in size, located at the border of the temporal macula. This corresponded to a deep scotoma similar in size to the physiologic blind spot on Humphrey visual field 24-2 testing. There was mild hypoautofluoresence of this lesion on autofluorescence, hypofluorescence on fluorescein angiography, and focal attenuation of a small artery just distal to the bifurcation of an artery supplying the involved area. Spectral domain optical coherence tomography through the lesion conveyed hyperreflectivity most prominent in the inner and outer plexiform layers, with extension of the hyperreflectivity into the ganglion cell and inner nuclear layers. Spectral domain optical coherence tomography angiography demonstrated arteriolar and capillary dropout, more pronounced in the superficial retinal layer compared to the deeper retinal layer. At 1-month follow-up, his scotoma improved with monitoring, with reduction from -32 dB to -7 dB on Humphrey visual field testing. There was clinical resolution of the area of graying and decreased hyperreflectivity on spectral domain optical coherence tomography, with atrophy of the inner retina. Spectral domain optical coherence tomography angiography showed progression of arteriolar and capillary dropout, more so in the superficial than in the deep capillary plexus. We describe a case of small artery occlusion in a previously healthy patient, 4 days after vaccination against N. meningitidis and yellow fever. Fluorescein angiography yielded greater diagnostic value than OCTA for evaluating the occlusion, whereas spectral domain optical coherence tomography angiography enabled better visualization of capillary dropout and layer-specific assessment. Further research is required to determine whether vaccination in general, or directed specifically at N. meningitidis or yellow fever, is associated with small vessel vasculopathy and the underlying pathogenesis.

Retinal nerve fiber layer thinning: a window into rapid eye movement sleep behavior disorders in Parkinson's disease.

PubMed

Yang, Zi-Jiao; Wei, Jing; Mao, Cheng-Jie; Zhang, Jin-Ru; Chen, Jing; Ji, Xiao-Yan; Liu, Jun-Yi; Shen, Yun; Xiong, Kang-Ping; Huang, Jun-Ying; Yang, Ya-Ping; Liu, Chun-Feng

2016-12-01

Retinal nerve fiber layer (RNFL) thinning occurs in Parkinson's disease (PD) and other neurodegenerative diseases. Idiopathic RBD (iRBD) is a well-established prodromal hallmark of synucleinopathies and occurs secondary to many neurodegenerative diseases, including PD. The aim of this study is to determine whether or not retinal structures are altered with the onset of rapid eye movement (REM) sleep behavior disorders (RBD). In all, a total of 63 patients with PD, 14 patients with idiopathic RBD, and 26 sex- and age-matched healthy controls were enrolled and underwent optical coherence tomography measurements (HD-OCT (Zeiss) ) for the average and every quadrant of RNFL thickness. The REM Sleep Behavior Disorder Screening Questionnaire (RBDSQ) was used to classify PD patients with clinically probable RBD (PD + pRBD) or without probable RBD (PD - pRBD). Patients with iRBD were identified by polysomnography. For patients with RBD (idiopathic or secondary to PD), we found a significant decrease in RNFL thickness compared with groups without RBD (PD - pRBD and healthy controls) (all p < 0.05). Average RNFL thickness in patients with iRBD is significantly thinner than in healthy controls (p < 0.05). In PD, the average RNFL thickness was dramatically thinner in the PD + pRBD group than the PD - pRBD group (p < 0.005). Compared with healthy controls, RNFL thickness was slightly thinner in the drug-naive PD group but not the PD group with drug treatment. Multiple linear regression analysis showed that RBDSQ score was negatively associated with average and inferior RNFL variation in PD (all p < 0.005). The findings show that RNFL was slightly but significantly thinner in idiopathic RBD. In PD, RNFL thickness may vary depending on the presence of RBD.

On the contribution of Heinrich Bruns to theoretical geometrical optics. With consideration of his correspondence with scientists of the Zeiss Company in Jena 1888-1893. (German Title: Über den Beitrag von Heinrich Bruns zur theoretischen geometrischen Optik Unter Berücksichtigung seines Briefwechsels mit Wissenschaftlern der Zeiss-Werke in Jena 1888-1893)

NASA Astrophysics Data System (ADS)

Ilgauds, Hans-Joachim; Münzel, Gisela

This paper describes the works of Heinrich Bruns, director of the Leipzig University Observatory, on theoretical geometrical optics, which followed an outstanding tradition in Leipzig. Bruns and his pupils did not stop at theoretical considerations, but applied their findings to practical questions. Bruns' correspondence with opticians of the Zeiss Company in Jena, so far known only fragmentarily, gives impressive evidence of their friendly relationship characterized by mutual regard and stimulation.

Retinal amyloid pathology and proof-of-concept imaging trial in Alzheimer’s disease

PubMed Central

Koronyo, Yosef; Biggs, David; Barron, Ernesto; Boyer, David S.; Pearlman, Joel A.; Au, William J.; Kile, Shawn J.; Blanco, Austin; Fuchs, Dieu-Trang; Frautschy, Sally; Cole, Gregory M.; Miller, Carol A.; Hinton, David R.; Verdooner, Steven R.; Black, Keith L.

2017-01-01

BACKGROUND. Noninvasive detection of Alzheimer’s disease (AD) with high specificity and sensitivity can greatly facilitate identification of at-risk populations for earlier, more effective intervention. AD patients exhibit a myriad of retinal pathologies, including hallmark amyloid β-protein (Aβ) deposits. METHODS. Burden, distribution, cellular layer, and structure of retinal Aβ plaques were analyzed in flat mounts and cross sections of definite AD patients and controls (n = 37). In a proof-of-concept retinal imaging trial (n = 16), amyloid probe curcumin formulation was determined and protocol was established for retinal amyloid imaging in live patients. RESULTS. Histological examination uncovered classical and neuritic-like Aβ deposits with increased retinal Aβ42 plaques (4.7-fold; P = 0.0063) and neuronal loss (P = 0.0023) in AD patients versus matched controls. Retinal Aβ plaque mirrored brain pathology, especially in the primary visual cortex (P = 0.0097 to P = 0.0018; Pearson’s r = 0.84–0.91). Retinal deposits often associated with blood vessels and occurred in hot spot peripheral regions of the superior quadrant and innermost retinal layers. Transmission electron microscopy revealed retinal Aβ assembled into protofibrils and fibrils. Moreover, the ability to image retinal amyloid deposits with solid-lipid curcumin and a modified scanning laser ophthalmoscope was demonstrated in live patients. A fully automated calculation of the retinal amyloid index (RAI), a quantitative measure of increased curcumin fluorescence, was constructed. Analysis of RAI scores showed a 2.1-fold increase in AD patients versus controls (P = 0.0031). CONCLUSION. The geometric distribution and increased burden of retinal amyloid pathology in AD, together with the feasibility to noninvasively detect discrete retinal amyloid deposits in living patients, may lead to a practical approach for large-scale AD diagnosis and monitoring. FUNDING. National Institute on Aging award (AG044897) and The Saban and The Marciano Family Foundations. PMID:28814675

High-resolution contrast-enhanced optical coherence tomography in mice retinae

NASA Astrophysics Data System (ADS)

Sen, Debasish; SoRelle, Elliott D.; Liba, Orly; Dalal, Roopa; Paulus, Yannis M.; Kim, Tae-Wan; Moshfeghi, Darius M.; de la Zerda, Adam

2016-06-01

Optical coherence tomography (OCT) is a noninvasive interferometric imaging modality providing anatomical information at depths of millimeters and a resolution of micrometers. Conventional OCT images limit our knowledge to anatomical structures alone, without any contrast enhancement. Therefore, here we have, for the first time, optimized an OCT-based contrast-enhanced imaging system for imaging single cells and blood vessels in vivo inside the living mouse retina at subnanomolar sensitivity. We used bioconjugated gold nanorods (GNRs) as exogenous OCT contrast agents. Specifically, we used anti-mouse CD45 coated GNRs to label mouse leukocytes and mPEG-coated GNRs to determine sensitivity of GNR detection in vivo inside mice retinae. We corroborated OCT observations with hyperspectral dark-field microscopy of formalin-fixed histological sections. Our results show that mouse leukocytes that otherwise do not produce OCT contrast can be labeled with GNRs leading to significant OCT intensity equivalent to a 0.5 nM GNR solution. Furthermore, GNRs injected intravenously can be detected inside retinal blood vessels at a sensitivity of ˜0.5 nM, and GNR-labeled cells injected intravenously can be detected inside retinal capillaries by enhanced OCT contrast. We envision the unprecedented resolution and sensitivity of functionalized GNRs coupled with OCT to be adopted for longitudinal studies of retinal disorders.

SDF-1 is both necessary and sufficient to promote proliferative retinopathy

PubMed Central

Butler, Jason M.; Guthrie, Steven M.; Koc, Mehmet; Afzal, Aqeela; Caballero, Sergio; Brooks, H. Logan; Mames, Robert N.; Segal, Mark S.; Grant, Maria B.; Scott, Edward W.

2005-01-01

Diabetic retinopathy is the leading cause of blindness in working-age adults. It is caused by oxygen starvation in the retina inducing aberrant formation of blood vessels that destroy retinal architecture. In humans, vitreal stromal cell–derived factor–1 (SDF-1) concentration increases as proliferative diabetic retinopathy progresses. Treatment of patients with triamcinolone decreases SDF-1 levels in the vitreous, with marked disease improvement. SDF-1 induces human retinal endothelial cells to increase expression of VCAM-1, a receptor for very late antigen–4 found on many hematopoietic progenitors, and reduce tight cellular junctions by reducing occludin expression. Both changes would serve to recruit hematopoietic and endothelial progenitor cells along an SDF-1 gradient. We have shown, using a murine model of proliferative adult retinopathy, that the majority of new vessels formed in response to oxygen starvation originate from hematopoietic stem cell–derived endothelial progenitor cells. We now show that the levels of SDF-1 found in patients with proliferative retinopathy induce retinopathy in our murine model. Intravitreal injection of blocking antibodies to SDF-1 prevented retinal neovascularization in our murine model, even in the presence of exogenous VEGF. Together, these data demonstrate that SDF-1 plays a major role in proliferative retinopathy and may be an ideal target for the prevention of proliferative retinopathy. PMID:15630447

[Bilateral abnormalities in central serous chorioretinopathy seen in optical coherence tomography, ultra-widefield fluorescein angiography and microperimetry--case report].

PubMed

Tylus, Magdalena; Święch-Zubilewicz, Anna; Dolar-Szczasny, Joanna; Mackiewicz, Jerzy

2015-01-01

Central serous chorioretinopathy is a common retinopathy, which is manifested by the idiopathic detachment of the neurosensory retina in the posterior pole, secondary to fluid leakage from choroidal vessels at the level of retinal pigment epithelium. The disease is typically unilateral and affects young men. We present a case of a 48-year old man, admitted to the Department of Vitreo-Retinal Surgery, Medical University in Lublin, reporting vision impairment in his right eye. The bilateral ocular exam followed by optical coherence tomography, ultra-widefield fluorescein angiography and microperimetry revealed bilateral central serous chorioretinopathy. This case presents a bilateral manifestation of central serous chorioretinopathy and emphasizes the role of advanced diagnostic imaging techniques in analyzing retinal function and disease management.

Nongranulomatous anterior uveitis in a patient with Usher syndrome.

PubMed

Alzuhairy, Sultan Abdulaziz S; Alfawaz, Abdullah

2013-10-01

A 34-year-old female with Usher syndrome, but no family history of similar illness, presented with complaints of vision reduction, redness, and photophobia. Biomicroscopic examination showed mildly injected conjunctivae bilateral, small, round keratic precipitates; bilateral +2 cells with no flare reaction in the anterior chamber; and bilateral posterior subcapsular cataracts. No associated posterior synechiae, angle neovascularization, or iris changes were detected; normal intraocular pressures were obtained. Fundus examination demonstrated waxy pallor of both optic nerves, marked vasoconstriction in retinal vessels, and retinal bone spicule pigment formation, with a normal macula. Electroretinography confirmed the diagnosis of retinitis pigmentosa, optical coherent tomography was normal and otolaryngology consultation was conducted. To our knowledge, an association between Usher syndrome and bilateral nongranulomatous anterior uveitis has not been previously reported, and our purpose is to report this association.

Concurrent OCT imaging of stimulus evoked retinal neural activation and hemodynamic responses

NASA Astrophysics Data System (ADS)

Son, Taeyoon; Wang, Benquan; Lu, Yiming; Chen, Yanjun; Cao, Dingcai; Yao, Xincheng

2017-02-01

It is well established that major retinal diseases involve distortions of the retinal neural physiology and blood vascular structures. However, the details of distortions in retinal neurovascular coupling associated with major eye diseases are not well understood. In this study, a multi-modal optical coherence tomography (OCT) imaging system was developed to enable concurrent imaging of retinal neural activity and vascular hemodynamics. Flicker light stimulation was applied to mouse retinas to evoke retinal neural responses and hemodynamic changes. The OCT images were acquired continuously during the pre-stimulation, light-stimulation, and post-stimulation phases. Stimulus-evoked intrinsic optical signals (IOSs) and hemodynamic changes were observed over time in blood-free and blood regions, respectively. Rapid IOSs change occurred almost immediately after stimulation. Both positive and negative signals were observed in adjacent retinal areas. The hemodynamic changes showed time delays after stimulation. The signal magnitudes induced by light stimulation were observed in blood regions and did not show significant changes in blood-free regions. These differences may arise from different mechanisms in blood vessels and neural tissues in response to light stimulation. These characteristics agreed well with our previous observations in mouse retinas. Further development of the multimodal OCT may provide a new imaging method for studying how retinal structures and metabolic and neural functions are affected by age-related macular degeneration (AMD), glaucoma, diabetic retinopathy (DR), and other diseases, which promises novel noninvasive biomarkers for early disease detection and reliable treatment evaluations of eye diseases.

Complement factor h is critical in the maintenance of retinal perfusion.

PubMed

Lundh von Leithner, Peter; Kam, Jaimie Hoh; Bainbridge, James; Catchpole, Ian; Gough, Gerald; Coffey, Peter; Jeffery, Glen

2009-07-01

Vascular pathologies are known to be associated with age-related macular degeneration. Recently, age-related macular degeneration was associated with a single-nucleotide substitution of the complement factor H (CFH) gene, part of the alternative pathway of the complement system, a critical element in the innate immune response. Such polymorphisms are found in more than 50% of cases of age-related macular degeneration. Here we show that the absence of CFH causes an autoimmune response that targets the vascular endothelium of both the inner and outer retinal vascular networks. In CFH-knockout (cfh(-/-)) mice, C3 and C3b, key components of the complement system, are progressively deposited on retinal vessels, which subsequently become restricted and wither, resulting in a reduction of retinal blood supply. This result leads to increased oxygen stress. While such effects are not systemic, these structural changes are mirrored in functional changes with a substantial decline in retinal blood flow dynamics. When the system is challenged functionally by laser-induced choroidal neovascularization, fluorescein leakage was significantly smaller in cfh(-/-) mice compared with controls, likely due to reduced retinal perfusion. These data reveal that in both the presence and absence of exogenous challenge to the innate immune system, CFH is required to maintain normal levels of retinal perfusion. It is likely that C3 and C3b accumulation in the aged CFH-deficient retina is associated with complement-mediated retinal endothelium destruction.

Twelve-hour reproducibility of retinal and optic nerve blood flow parameters in healthy individuals.

PubMed

Luksch, Alexandra; Lasta, Michael; Polak, Kaija; Fuchsjäger-Mayrl, Gabriele; Polska, Elzbieta; Garhöfer, Gerhard; Schmetterer, Leopold

2009-11-01

The aim of the present study was to investigate the reproducibility and potential diurnal variation of optic nerve head and retinal blood flow parameters in healthy individuals over a period of 12 hr. We measured optic nerve head and retinal blood flow parameters in 16 healthy male non-smoking individuals at five time-points during the day (08:00, 11:00, 14:00, 17:00 and 20:00 hr). Outcome parameters were perimacular white blood cell flux (as assessed with the blue field entoptic technique), blood velocities in retinal veins (as assessed with bi-directional laser Doppler velocimetry), retinal arterial and venous diameters (as assessed with the retinal vessel analyser), optic nerve head blood flow, volume and velocity (as assessed with single point and scanning laser Doppler flowmetry) and blood velocities in the central retinal artery (as assessed with colour Doppler imaging). The coefficient of variation and the maximum change from baseline in an individual were calculated for each outcome parameter. No diurnal variation in optic nerve head or retinal blood flow was observed with any of the techniques employed. Coefficients of variation were between 1.6% and 18.5% for all outcome parameters. The maximum change from baseline in an individual was much higher, ranging from 3.7% to 78.2%. Our data indicate that in healthy individuals the selected techniques provide adequate reproducibility to be used in clinical studies. However, in patients with eye diseases and reduced vision the reproducibility may be considerably worse.

Improvement of retinal functions after ischemia with L-arginine and its derivatives.

PubMed

Liu, S X; Chiou, G C; Varma, R S

1995-01-01

Retinal ischemia was created by occlusion of rat central retinal artery for 30 minutes. The loss of retinal function was indicated by the loss of b-wave of electroretinogram. The recovery of retinal function after reperfusion of central retinal artery was observed with the gradual recovery of b-wave amplitude to approximately 20% of original b-wave amplitude. When L-arginine (RVC-579) was administered at the time of retina ischemia, the b-wave amplitudes recovered up to 64% of original height and were significantly higher than corresponding controls at 120, 180, and 240 min after ischemia. When the derivative of L-arginine, N alpha-benzoyl-L-arginine ethyl ester (RVC-578), was administered, the b-wave recovery was significantly higher than corresponding controls at 90, 120, 180, and 240 min after ischemia; the recovery reached 51% of the original b-wave value. These results indicate that the L-arginine and its lipophilic derivatives could be used for the treatment of ischemic retinopathy. Since L-arginine is a natural amino acid, it is not expected to produce major side effects, if any, and could pave the way for the development of a safer drug to be used in the clinics. Compounds which increase the formation of NO in vivo, dilate blood vessels. Both L-arginine and RVC-578 can be placed in this category. They may improve effects of retinal ischemia by increasing NO production.

The spectrum of retinopathy in adults with Plasmodium falciparum malaria

PubMed Central

Maude, Richard J.; Beare, Nicholas A.V.; Sayeed, Abdullah Abu; Chang, Christina C.; Charunwatthana, Prakaykaew; Faiz, M. Abul; Hossain, Amir; Yunus, Emran Bin; Hoque, M. Gofranul; Hasan, Mahtab Uddin; White, Nicholas J.; Day, Nicholas P.J.; Dondorp, Arjen M.

2009-01-01

Summary A specific retinopathy has been described in African children with cerebral malaria, but in adults this has not been extensively studied. Since the structure and function of the retinal vasculature greatly resembles the cerebral vasculature, study of retinal changes can reveal insights into the pathophysiology of cerebral malaria. A detailed observational study of malarial retinopathy in Bangladeshi adults was performed using high-definition portable retinal photography. Retinopathy was present in 17/27 adults (63%) with severe malaria and 14/20 adults (70%) with cerebral malaria. Moderate or severe retinopathy was more frequent in cerebral malaria (11/20, 55%) than in uncomplicated malaria (3/15, 20%; P = 0.039), bacterial sepsis (0/5, 0%; P = 0.038) or healthy controls (0/18, 0%; P < 0.001). The spectrum of malarial retinopathy was similar to that previously described in African children, but no vessel discolouration was observed. The severity of retinal whitening correlated with admission venous plasma lactate (P = 0.046), suggesting that retinal ischaemia represents systemic ischaemia. In conclusion, retinal changes related to microvascular obstruction were common in adults with severe falciparum malaria and correlated with disease severity and coma, suggesting that a compromised microcirculation has important pathophysiological significance in severe and cerebral malaria. Portable retinal photography has potential as a valuable tool to study malarial retinopathy. PMID:19344925

Colour Doppler analysis of ophthalmic vessels in the diagnosis of carotic artery and retinal vein occlusion, diabetic retinopathy and glaucoma: systematic review of test accuracy studies.

PubMed

Bittner, Mario; Faes, Livia; Boehni, Sophie C; Bachmann, Lucas M; Schlingemann, Reinier O; Schmid, Martin K

2016-12-07

Colour Doppler analysis of ophthalmic vessels has been proposed as a promising tool in the diagnosis of various eye diseases, but the available diagnostic evidence has not yet been assessed systematically. We performed a comprehensive systematic review of the literature on the diagnostic properties of Colour Doppler imaging (CDI) assessing ophthalmic vessels and provide an inventory of the available evidence. Eligible papers were searched electronically in (Pre) Medline, Embase and Scopus, and via cross-checking of reference lists. The minimum requirement to be included was the availability of original data and the possibility to construct a two-by-two table. Study selection, critical appraisal using the QUADAS II instrument and extraction of salient study characteristics was made in duplicate. Sensitivity and specificity was computed for each study. We included 11 studies (15 two-by-two tables) of moderate methodological quality enrolling 820 participants (range 30 to 118). In 44.4% participants were female (range 37-59% in specific subgroups). CDI was assessed for internal carotid stenosis, diabetic retinopathy, glaucoma, and branch or central retinal vein occlusion diagnosis. There was insufficient data to pool the results for specific illnesses. For the assessments of ophthalmic arteries, mean sensitivity was 0.69 (range 0.27-0.96) with a corresponding mean specificity of 0.83 (range 0.70-0.96). Mean sensitivity of the central retinal artery assessments was 0.58 (range 0.31-0.84) and the corresponding mean specificity was 0.82 (range 0.63-0.94). Robust assessments of the diagnostic value of colour Doppler analysis remain uncommon, limiting the possibilities to extrapolate its true potential for clinical practice. PROSPERO 2014:CRD42014014027.

HEMI-TEMPORAL INTERNAL LIMITING MEMBRANE PEELING IS AS EFFECTIVE AND SAFE AS CONVENTIONAL FULL PEELING FOR MACULAR HOLE SURGERY.

PubMed

Shiono, Akira; Kogo, Jiro; Sasaki, Hiroki; Yomoda, Ryo; Jujo, Tatsuya; Tokuda, Naoto; Kitaoka, Yasushi; Takagi, Hitoshi

2018-05-09

To investigate the efficacy of hemi-temporal internal limiting membrane (ILM) peeling for idiopathic macular hole. The medical records of patients with macular holes who had undergone vitrectomy with ILM peeling were studied. Forty-two eyes with macular hole were divided into 2 groups based on surgical procedure (hemi-temporal ILM peeling [hemi group]: 15 eyes; 360° ILM peeling [360° group]: 27 eyes). The closure rates and distances between the optic disc and the intersection of two retinal vessels most closely located nasally or temporally to the macular hole were compared. The primary closure rates were not significantly different between the two groups (hemi group: 93.3%; 360° group: 92.5%, P = 0.92). The temporal retinal vessels in the hemi group were displaced 120.5 ± 102.0 µm toward the optic disc at 1 week postoperatively, which did not differ significantly from the 360° group (136.1 ± 106.1 µm) (P = 0.107). However, the nasal retinal vessels in the hemi group were displaced by 42.4 ± 42.9 µm at 1 week postoperatively, which was significantly less than the 90.1 ± 77.3 µm displacement seen in the 360° group (P = 0.040). Hemi-temporal ILM peeling may be preferable to 360° ILM peeling because of less displacement of the retina and greater safety.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.

Shifts in renin-angiotensin system components, angiogenesis, and oxidative stress-related protein expression in the lamina cribrosa region of streptozotocin-induced diabetic mice.

PubMed

Qian, Xiaobing; Lin, Leilei; Zong, Yao; Yuan, Yongguang; Dong, Yanmin; Fu, Yue; Shao, Wanwen; Li, Yujie; Gao, Qianying

2018-03-01

This study aimed to analyse shifts in renin-angiotensin system (RAS) components, angiogenesis, and oxidative stress-related protein expression in the lamina cribrosa (LC) region in streptozotocin (STZ)-induced diabetic mice. Six months after diabetes induction, the retinal vessels of male C57BL/6 J mice were observed by colour photography, fundus fluorescein angiography (FFA), and immunofluorescent staining following incubation with CD31. Immunofluorescence for glial fibrillary acidic protein (GFAP), alpha-smooth muscle actin (α-SMA),and NG2 was also performed. Angiotensin-converting enzyme 1 (ACE1), angiotensin II type I receptor (AT1R), renin, hypoxia-inducible factor 1-alpha (HIF-1α), vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor 2 (VEGFR2), and haeme oxygenase 1 (HO-1) expression levels were confirmed by immunohistochemical and western blotting analyses. Compared with control mice, diabetic mice had significantly higher blood glucose concentrations (p < 0.001) and significantly lower body weights (p < 0.001). Colour photography and FFA did not reveal any vessel abnormalities in the diabetic mice; however, immunostaining of whole-mount retinas revealed an increased number of retinal vessels. Furthermore, histopathological staining showed significant reduction in the whole retinal thickness. GFAP expression was slightly higher, whereas fewer NG2 + pericytes were observed in diabetic mice than in control mice. ACE1, AT1R, renin, HIF-1α, VEGF, VEGFR2, and HO-1 expression were up-regulated in the LC of the STZ-induced diabetic mice. Collectively, ACE 1, AT1R, HIF-1α, VEGF, VEGFR2, and HO-1 activation in the LC region in diabetic mice may be involved in diabetes via the RAS and induction of angiogenesis and oxidative stress.

In 6- to 8-year-old children, hair cortisol is associated with body mass index and somatic complaints, but not with stress, health-related quality of life, blood pressure, retinal vessel diameters, and cardiorespiratory fitness.

PubMed

Gerber, Markus; Endes, Katharina; Brand, Serge; Herrmann, Christian; Colledge, Flora; Donath, Lars; Faude, Oliver; Pühse, Uwe; Hanssen, Henner; Zahner, Lukas

2017-02-01

Hair cortisol measurement has become an increasingly accepted approach in endocrinology and biopsychology. However, while in adult research hair cortisol has been proposed as a relevant biomarker for chronic stress (and its adverse consequences), studies with children are scarce. Therefore, the goal of the present exploratory study was to examine the associations between hair cortisol concentrations (HCCs), stress, and a series of health-related outcomes in a sample of Swiss first grade schoolchildren. The sample consisted of 318 children (53% girls, M age =7.26, SD=0.35). Hair strands were taken near the scalp from a posterior vertex position, and HCCs were tested for the first 3-cm hair segment. Parents provided information about their children's age, gender, parental education, children's stress (recent critical life events, daily hassles), health-related quality of life, and psychosomatic complaints. Body composition, blood pressure, retinal vessel diameters, and cardiorespiratory fitness were measured with established methods. In multiple regression analyses, higher HCCs were weakly associated with increased BMI in girls (β=0.22, p<0.001), whereas higher HCCs were associated with increased somatic complaints in boys (β=0.20, p<0.05). No significant relationships were found between HCCs and parental reports of stress, health-related quality of life, blood pressure, retinal vessel diameters, and cardiorespiratory fitness. Although small significant relationships were found between HCCs, BMI and somatic complaints, the findings of this exploratory study challenge the view that HCCs can be used as a reliable biomarker of recent critical life events, daily hassles, health-related quality of life, and cardiovascular health indicators in non-clinical young children. Copyright © 2016 Elsevier Ltd. All rights reserved.

Changes in the retrobulbar arterial circulation after decrease of the elevated intraocular pressure in men and women with primary open angle glaucoma.

PubMed

Marjanović, Ivan; Martinez, Antonio; Marjanović, Marija; Kontić, Djordje; Hentova-Senćanić, Paraskeva; Marković, Vujica; Bozić, Marija

2013-01-01

An altered perfusion of the optic nerve head has been proposed as a pathogenic factor of glaucoma. The aim of this study was to evaluate the changes of the hemodynamic parameters in the retrobulbar arterial circulation after decrease of the elevated intraocular pressure (IOP) in women and men with primary open angle glaucoma. The study included 60 patients (33 males and 27 females) older than 50 years, with diagnosed and treated primary open angle glaucoma (77 eyes of 39 patients had increased IOP, > 25 mm Hg).They were examined at the Clinic of Eye Diseases (complete ophthalmologic exam) and Clinic of Neurology, Clinical Center of Serbia, Belgrade, from December 2009 to December 2010. Imaging of hemodynamic parameters of three retrobulbar arterial vessels: ophthalmic, central retinal and posterior ciliary arteries with color Doppler was performed. Among women, hemodynamic arterial parameter of the peak-systolic velocity was increased in the central retinal artery and decreased in the ophthalmic artery and posterior ciliary arteries; end-diastolic velocity was increased in all three retrobulbar vascular levels; Pourcelot resistivity index was increased, but pulsatility index was decreased in all three vessels. Among men, peak-systolic velocity, end-diastolic velocity and pulsatility index were decreased in all three vessels; resistivity index was increased in the ophthalmic artery, but decreased in the central retinal artery and posterior ciliary arteries. There was a significant change of the ophthalmic artery pulsatility index in women, and the end-diastolic velocity of the ophthalmic artery in men. There was a difference of the retrobulbar arterial circulation between women and men with primary open angle glaucoma after decrease of the elevated intraocular pressure.The role of vascular factors in the supply of the optic disc neuroretinal rim is important.

Impact of anatomical parameters on optical coherence tomography retinal nerve fiber layer thickness abnormality patterns

NASA Astrophysics Data System (ADS)

Baniasadi, Neda; Wang, Mengyu; Wang, Hui; Jin, Qingying; Mahd, Mufeed; Elze, Tobias

2017-02-01

Purpose: To evaluate the effects of four anatomical parameters (angle between superior and inferior temporal retinal arteries [inter-artery angle, IAA], optic disc [OD] rotation, retinal curvature, and central retinal vessel trunk entry point location [CRVTL]) on retinal nerve fiber layer thickness (RNFLT) abnormality marks by OCT machines. Methods: Cirrus OCT circumpapillary RNFLT measurements and Humphrey visual fields (HVF 24-2) of 421 patients from a large glaucoma clinic were included. Ellipses were fitted to the OD borders. Ellipse rotation relative to the vertical axis defined OD rotation. CRVTL was manually marked on the horizontal axis of the ellipse on the OCT fundus image. IAA was calculated between manually marked retinal artery locations at the 1.73mm radius around OD. Retinal curvature was determined by the inner limiting membrane on the horizontal B-scan closest to the OD center. For each location on the circumpapillary scanning area, logistic regression was used to determine if each of the four parameters had a significant impact on RNFLT abnormality marks independent of disease severity. The results are presented on spatial maps of the entire scanning area. Results: Variations in IAA significantly influenced abnormality marks on 38.8% of the total scanning area, followed by CRVTL (19.2%) and retinal curvature (18.7%). The effect of OD rotation was negligible (<1%). Conclusions: A natural variation in IAA, retinal curvature, and CRVTL can affect OCT abnormality ratings, which may bias clinical diagnosis. Our spatial maps may help OCT manufacturers to introduce location specific norms to ensure that abnormality marks indicate ocular disease instead of variations in eye anatomy.

Retinal blood flow in type 1 diabetic patients with no or mild diabetic retinopathy during euglycemic clamp.

PubMed

Pemp, Berthold; Polska, Elzbieta; Garhofer, Gerhard; Bayerle-Eder, Michaela; Kautzky-Willer, Alexandra; Schmetterer, Leopold

2010-09-01

To compare total retinal blood flow in diabetic patients with no or mild nonproliferative diabetic retinopathy and healthy control subjects and to investigate in patients whether there is a difference between retinal blood flow before morning insulin and under normoglycemic conditions using a glucose clamp. Twenty patients with type 1 diabetes with no or mild diabetic retinopathy were included in this open parallel-group study, and 20 healthy age- and sex-matched subjects were included as control subjects. Retinal blood flow was assessed by combining velocity measurements using laser Doppler velocimetry and diameter measurements using a commercially available dynamic vessel analyzer. Measurements were performed before and during a euglycemic clamp. Total retinal blood flow was higher in diabetic patients (53 +/- 16 microl/min) than in healthy subjects (43 +/- 16 microl/min; P = 0.034 between groups). When plasma glucose in diabetic patients was reduced from 9.3 +/- 1.7 to 5.3 +/- 0.5 mmol/l (P < 0.001) retinal blood flow decreased to 49 +/- 15 microl/min (P = 0.0003 vs. baseline). Total retinal blood flow during the glucose clamp was not significantly different from blood flow in normal control subjects (P = 0.161). Type 1 diabetic patients with no or only mild diabetic retinopathy have increased retinal blood flow before their morning insulin dosage. Blood flow is reduced toward normal during euglycemic conditions. Retinal blood flow may fluctuate significantly with fluctuating plasma glucose levels, which may contribute to the microvascular changes seen in diabetic retinopathy.

Quantitative Assessment of Retinopathy Using Multi-parameter Image Analysis

PubMed Central

Ghanian, Zahra; Staniszewski, Kevin; Jamali, Nasim; Sepehr, Reyhaneh; Wang, Shoujian; Sorenson, Christine M.; Sheibani, Nader; Ranji, Mahsa

2016-01-01

A multi-parameter quantification method was implemented to quantify retinal vascular injuries in microscopic images of clinically relevant eye diseases. This method was applied to wholemount retinal trypsin digest images of diabetic Akita/+, and bcl-2 knocked out mice models. Five unique features of retinal vasculature were extracted to monitor early structural changes and retinopathy, as well as quantifying the disease progression. Our approach was validated through simulations of retinal images. Results showed fewer number of cells (P = 5.1205e-05), greater population ratios of endothelial cells to pericytes (PCs) (P = 5.1772e-04; an indicator of PC loss), higher fractal dimension (P = 8.2202e-05), smaller vessel coverage (P = 1.4214e-05), and greater number of acellular capillaries (P = 7.0414e-04) for diabetic retina as compared to normal retina. Quantification using the present method would be helpful in evaluating physiological and pathological retinopathy in a high-throughput and reproducible manner. PMID:27186534

Über den Beitrag von Heinrich Bruns zur theoretischen geometrischen Optik - unter Berücksichtigung seines Briefwechsels mit Wissenschaftlern der Zeiss-Werke in Jena 1888 - 1893.

NASA Astrophysics Data System (ADS)

Ilgauds, H.-J.; Münzel, G.

Heinrich Bruns, director of the Leipzig University Observatory, was working on theoretical geometrical optics, and applied this to practical questions. His correspondence with opticians of the Zeiss Company in Jena gives evidence of their mutual regard and inspiration.

Antiangiogenic activity of aganirsen in nonhuman primate and rodent models of retinal neovascular disease after topical administration.

PubMed

Cloutier, Frank; Lawrence, Matthew; Goody, Robin; Lamoureux, Stéphanie; Al-Mahmood, Salman; Colin, Sylvie; Ferry, Antoine; Conduzorgues, Jean-Pascal; Hadri, Amel; Cursiefen, Claus; Udaondo, Patricia; Viaud, Eric; Thorin, Eric; Chemtob, Sylvain

2012-03-09

Aganirsen, an antisense oligonucleotide inhibiting insulin receptor substrate (IRS)-1 expression, has been shown to promote the regression of pathologic corneal neovascularization in patients. In this study, the authors aimed to demonstrate the antiangiogenic activity of aganirsen in animal models of retinal neovascularization. Eyedrops of aganirsen were applied daily in nonhuman primates after laser-induced choroidal neovascularization (CNV; model of wet age-related macular degeneration [AMD]) and in newborn rats after oxygen-induced retinopathy (OIR; model of ischemic retinopathy). Retinal aganirsen concentrations were assessed in rabbits and monkeys after topical delivery (21.5, 43, or 86 μg). Clinical significance was further evaluated by determination of IRS-1 expression in monkey and human retinal biopsy specimens. Topical corneal application of aganirsen attenuated neovascular lesion development dose dependently in African green monkeys. The incidence of high-grade CNV lesions (grade IV) decreased from 20.5% in vehicle-treated animals to 1.7% (P < 0.05) at the 86-μg dose. Topical aganirsen inhibited retinal neovascularization after OIR in rats (P < 0.05); furthermore, a single intravitreal injection of aganirsen reduced OIR as effectively as ranibizumab, and their effects were additive. Significantly, topical applications of aganirsen did not interfere with physiological retinal vessel development in newborn rats. Retinal delivery after topical administration was confirmed, and retinal expression of IRS-1 was demonstrated to be elevated in patients with subretinal neovascularization and AMD. Topical application of aganirsen offers a safe and effective therapy for both choroidal and retinal neovascularization without preventing its normal vascularization. Together, these findings support the clinical testing of aganirsen for human retinal neovascular diseases.

Oxygen Saturation of Retinal Vessels in All Stages of Diabetic Retinopathy and Correlation to Ultra-Wide Field Fluorescein Angiography.

PubMed

Guduru, Abhilash; Martz, Teresa G; Waters, Alexa; Kshirsagar, Abhijit V; Garg, Seema

2016-10-01

The purpose of this study was to determine retinal hemoglobin oxygen saturation (SO2) in patients with diabetic retinopathy (DR) using retinal oximetry (RO) and to correlate the degree of retinal ischemia using intravenous fluorescein angiography (IVFA). This is a single-center cross-sectional cohort study. Twenty-seven controls and 60 adult patients with diabetes mellitus (16 without DR and 44 with DR) were enrolled. Patients were stratified according to DR severity. Using RO, SO2 was measured in major retinal arterioles (SaO2) and venules (SvO2). Using IVFA, the percentage of retinal ischemia in 31 patients with DR was calculated and correlated with RO. Pairwise one-way analysis of variance (ANOVA) showed a significant increase in SaO2 and SvO2 in patients with proliferative DR (PDR) compared with controls (SaO2: PDR, 100 ± 7% vs. controls, 91 ± 4% [P = 0.003]; SvO2: PDR, 66 ± 11% vs. controls, 53 ± 6% [P < 0.00001]). The percentage of retinal ischemia also increased with DR severity: ANOVA showed a significant difference in retinal ischemia between all categories of nonproliferative DR vs. PDR: 2.31 ± 2% vs. 7.92 ± 9% (P = 0.017), respectively. Pearson two-tailed correlation showed significant correlation between SaO2 and ischemia (R = 0.467, P = 0.011). Hemoglobin oxygen saturation of retinal arterioles and venules increases with DR severity; SaO2 correlates with increasing ischemia measured by IVFA. Retinal oximetry may complement current imaging strategies to noninvasively augment the diagnosis and risk stratification of patients with diabetes.

Effects of granulocyte colony stimulating factor on retinal leukocyte and erythrocyte flux in the human retina.

PubMed

Fuchsjäger-Mayrl, Gabriele; Malec, Magdalena; Polska, Elzbieta; Jilma, Bernd; Wolzt, Michael; Schmetterer, Leopold

2002-05-01

The blue-field entoptic technique was introduced more than 20 years ago to quantify perimacular white blood cell flux. However, a final confirmation that the perceived corpuscles represent leukocytes is still unavailable. The study design was randomized, placebo-controlled, and double masked with two parallel groups. Fifteen healthy male subjects received a single dose of granulocyte colony stimulating factor (G-CSF, 300 microg) and 15 other subjects received placebo. The following parameters were assessed at baseline and at 12 minutes and 8 hours after administration: retinal white blood cell flux, with the blue-field entoptic technique; retinal blood velocities, with bidirectional laser Doppler velocimetry; retinal venous diameter determined with a retinal vessel analyzer; and blood pressure and pulse rate determined by automated oscillometry and pulse oxymetry, respectively. After 12 minutes, G-CSF reduced total leukocyte count from 5.5 +/- 1.4 10(9)/L at baseline to 1.9 +/- 0.4 10(9)/L. This was paralleled by a 35% +/- 11% decrease in retinal white blood cell density. After 8 hours G-CSF increased total leukocyte counts to 20.0 +/- 4.4 10(9)/L. Again, this increase in circulating leukocytes was reflected by an increase in retinal white blood cell density (110% +/- 48%). All effects were significant at P < 0.001. By contrast, none of the other hemodynamic parameters was changed by administration of G-CSF. The results clearly indicate that the blue-field entoptic technique assesses leukocyte movement in the perimacular capillaries of the retina. Moreover, white blood cell density appears to adequately reflect the number of circulating leukocytes within the retinal microvasculature. Hence, an increase in retinal white blood cell density does not necessarily reflect retinal vasodilatation.

Effects of GH/IGF-I Axis on Retinal Vascular Morphology: Retinal Vascular Characteristics in a Clinical Setting with Severe IGF-I Deficiency.

PubMed

Sekeroglu, Hande Taylan; Kadayıfcılar, Sibel; Kasım, Burcu; Arslan, Umut; Ozon, Alev

2016-01-01

The purpose of this study was to assess retinal vascular characteristics of patients with Laron syndrome (LS) as a genetic model of IGF-I deficiency before and after rhIGF1/IGFBP3 treatment and to compare them with healthy controls. A total of 28 subjects (11 LS, and 17 controls) were enrolled. Patients with LS received combined rhIGF1/rhIGFBP3 1-2 mg/kg/d in a single dose and digital fundus imaging was performed. The number of branching points and tortuosity of retinal vessels were studied. Pre- and post-treatment findings were compared with each other and with controls. The number of branching points was significantly lower in patients with LS in comparison to controls (12.73 ± 3.41, and 17.47 ± 5.82 respectively, p = 0.012). This difference persisted after treatment (12.09 ± 2.66 post-treatment LS versus controls, p = 0.017). Tortuosity indices of nasal arteries (NA) were significantly less in LS than that of controls (upper NA 1.07 ± 0.04 and 1.12 ± 0.06 respectively p = 0.022; lower NA 1.07 ± 0.03 and 1.13 ± 0.07 respectively, p = 0.004). This difference also persisted following treatment (p < 0.05). Remaining vessels did not differ in tortuosity index. There was no significant difference of tortuosity index and number of branching points before and after treatment in patients with LS. Retinal vascular development may be adversely affected in the setting of severe IGF-I deficiency confirming a major role for GH/IGF-I axis during retinal vascular development in humans antenatally. Resolution of IGF-I deficiency following birth using rhIGF1, however, may not reverse these changes, suggesting that IGF-I may be necessary but insufficient by itself for postnatal angiogenesis.

Combined treatment for Coats’ disease: retinal laser photocoagulation combined with intravitreal bevacizumab injection was effective in two cases

PubMed Central

2014-01-01

Background The exact pathogenetic mechanisms of Coats’ disease remain unknown. In this report, we show two cases of Coats’ disease that achieved a favorable prognosis with the combined treatment of intravitreal bevacizumab (IVB) injection prior to photocoagulation, although both initially resisted photocoagulation therapy. Case presentations Case 1 was a 15-year-old boy with initial visual acuity of 0.4 OD. At the temporal retina, aneurysms and abnormal telangiectatic vessels were observed. Hard exudates and an exudative retinal detachment extended to the fovea. He was diagnosed as having Coats’ disease at stage 3A and we performed laser photocoagulation as an initial approach to treat peripheral aneurysms and telangiectatic vessels. After the treatment, the exudative retinal detachment was eased and visual acuity improved to 1.0; however, recurrence occurred after 5 months. The exudative change was resistant against laser photocoagulation therapy and we therefore added IVB as an adjuvant before photocoagulation. Fourteen days after IVB injection phased laser photocoagulation was given to cover the abnormal capillaries, aneurysms and the leakage area spotted in FA. A good prognosis was obtained with decreased exudation and improved visual acuity. Case 2 was an 11-year-old boy with decreased visual acuity of 0.15 OS at the initial visit. Hard exudates, retinal edema and serous retinal detachment were seen at the macula and peripheral retina. Fluorescein angiography revealed telangiectatic capillaries at the temporal retina. Our diagnosis was Coats’ disease at stage 3A. Extensive photocoagulation was performed as an initial treatment to the lesion. However, the exudative change was severe and resistant against the photocoagulation treatment. Therefore, we added IVB as an adjuvant before photocoagulation. Exudative change in the retina seemed to be eased 7 days after IVB injection, therefore, phased laser phototherapy was added to cover the abnormal capillaries. After the combination therapy, exudative change was remarkably ameliorated and better visual acuity was achieved. Conclusion Bevacizumab is considered an effective adjuvant for Coats’ disease with exudative change resistant to retinal photocoagulation therapy. PMID:24666524

An Approach to Evaluate Blurriness in Retinal Images with Vitreous Opacity for Cataract Diagnosis

PubMed Central

Xu, Liang

2017-01-01

Cataract is one of the leading causes of blindness in the world's population. A method to evaluate blurriness for cataract diagnosis in retinal images with vitreous opacity is proposed in this paper. Three types of features are extracted, which include pixel number of visible structures, mean contrast between vessels and background, and local standard deviation. To avoid the wrong detection of vitreous opacity as retinal structures, a morphological method is proposed to detect and remove such lesions from retinal visible structure segmentation. Based on the extracted features, a decision tree is trained to classify retinal images into five grades of blurriness. The proposed approach was tested using 1355 clinical retinal images, and the accuracies of two-class classification and five-grade grading compared with that of manual grading are 92.8% and 81.1%, respectively. The kappa value between automatic grading and manual grading is 0.74 in five-grade grading, in which both variance and P value are less than 0.001. Experimental results show that the grading difference between automatic grading and manual grading is all within 1 grade, which is much improvement compared with that of other available methods. The proposed grading method provides a universal measure of cataract severity and can facilitate the decision of cataract surgery. PMID:29065620

Plasma-activated medium suppresses choroidal neovascularization in mice: a new therapeutic concept for age-related macular degeneration.

PubMed

Ye, Fuxiang; Kaneko, Hiroki; Nagasaka, Yosuke; Ijima, Ryo; Nakamura, Kae; Nagaya, Masatoshi; Takayama, Kei; Kajiyama, Hiroaki; Senga, Takeshi; Tanaka, Hiromasa; Mizuno, Masaaki; Kikkawa, Fumitaka; Hori, Masaru; Terasaki, Hiroko

2015-01-09

Choroidal neovascularization (CNV) is the main pathogenesis of age-related macular degeneration (AMD), which leads to severe vision loss in many aged patients in most advanced country. CNV compromises vision via hemorrhage and retinal detachment on account of pathological neovascularization penetrating the retina. Plasma medicine represents the medical application of ionized gas "plasma" that is typically studied in the field of physical science. Here we examined the therapeutic ability of plasma-activated medium (PAM) to suppress CNV. The effect of PAM on vascularization was assessed on the basis of human retinal endothelial cell (HREC) tube formation. In mice, laser photocoagulation was performed to induce CNV (laser-CNV), followed by intravitreal injection of PAM. N-Acetylcysteine was used to examine the role of reactive oxygen species in PAM-induced CNV suppression. Fundus imaging, retinal histology examination, and electroretinography (ERG) were also performed to evaluate PAM-induced retinal toxicity. Interestingly, HREC tube formation and laser-CNV were both reduced by treatment with PAM. N-acetylcysteine only partly neutralized the PAM-induced reduction in laser-CNV. In addition, PAM injection had no effect on regular retinal vessels, nor did it show retinal toxicity in vivo. Our findings indicate the potential of PAM as a novel therapeutic agent for suppressing CNV.

[Peripheral refraction and retinal contour in children with myopia by results of refractometry and partial coherence interferometry].

PubMed

Tarutta, E P; Milash, S V; Tarasova, N A; Romanova, L I; Markosian, G A; Epishina, M V

2014-01-01

To determine the posterior pole contour of the eye based on the relative peripheral refractive error and relative eye length. A parallel study was performed, which enrolled 38 children (76 eyes) with myopia from -1.25 to -10.82 diopters. The patients underwent peripheral refraction assessment with WR-5100K Binocular Auto Refractometer ("Grand Seiko", Japan) and partial coherence tomography with IOLMaster ("Carl Zeiss", Germany) for the relative eye length in areas located 15 and 30 degrees nasal and temporal from the central fovea along the horizontal meridian. In general, refractometry and interferometry showed high coincidence of defocus signs and values for the areas located 15 and 30 degrees nasal as well as 15 degrees temporal from the fovea. However, in 41% of patients defocus signs determined by the two methods mismatched in one or more areas. Most of the mismatch cases were mild myopia. We suppose that such a mismatch is caused by optical peculiarities of the anterior eye segment that have an impact on refractometry results.

Argon laser choroidotomy for drainage of subretinal fluid.

PubMed

Bovino, J A; Marcus, D F; Nelsen, P T

1985-03-01

We used the argon laser to perforate the choroid and drain subretinal fluid during retinal detachment surgery in 24 consecutive patients. The procedure was successful in 23 of 24 patients (95.8%). The laser settings required for perforation ranged from 0.02 to 0.2 s and from 200 mW to 2.0 W. Because it is not necessary to enter the subretinal space with a solid, pointed object, laser choroidotomy may reduce the incidence of retinal perforation. In addition, the laser has the advantage of cauterizing small vessels during choroidal puncture, which may reduce bleeding at the time of drainage.

Statins affect ocular microcirculation in patients with hypercholesterolaemia.

PubMed

Terai, Naim; Spoerl, Eberhard; Fischer, Sabine; Hornykewycz, Karin; Haustein, Michael; Haentzschel, Janek; Pillunat, Lutz E

2011-09-01

To investigate the effect of statins on ocular microcirculation in patients with hypercholesterolaemia. Ten patients with hypercholesterolaemia were included in this study. The diameter of retinal vessels was measured continuously with the retinal vessel analyser (RVA) before and 4 weeks after statin therapy. After baseline assessment, a monochromatic luminance flicker was applied to evoke retinal vasodilation. Flicker response was then analysed after 50, 150 and 250 seconds after baseline measurement. Additionally, cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL) and triglyceride levels were obtained to find a possible correlation between retinal vessel diameter changes and lipid metabolism before and after statin therapy. The mean diameter of the arterioles before statin therapy at baseline was 106.3 ± 1.5 μm and the mean diameter of the venules at baseline was 127.3 ± 2.5 μm. The mean diameter of the arterioles 4 weeks before statin therapy was 107.3 ± 1.8 μm after 50 seconds, 107.9 ± 1.8 μm after 150 seconds and 108.0 ± 1.8 μm after 250 seconds (p = 0.01). The mean diameter of the venules 4 weeks before statin therapy was 128.0 ± 2.6 μm after 50 seconds, 128.2 ± 2.5 μm after 150 seconds and 128.2 ± 2.3 μm after 250 seconds (p = 0.01). The mean diameter of the arterioles 4 weeks after statin therapy at baseline was 107.1 ± 1.6 μm and the mean diameter of the venules at baseline was 127.7 ± 2.3 μm which was significantly different from measurements before statin therapy (p = 0.004). The diameter of the arterioles 4 weeks after statin therapy increased to 109.2 ± 2.1 μm after 50 seconds, to 110.6 ± 2.6 μm after 150 seconds and to 111.8 ± 2.3 μm after 250 seconds with statistical significance at all time points (p = 0.001). The mean diameter of the venules after statin therapy increased to 130.6 ± 2.7 μm after 50 seconds, to 132.1 ± 2.6 μm after 150 seconds and to 133.5 ± 3.0 μm after 250 seconds with statistical significance at all time points (p = 0.001). The present study demonstrated a significant increase in vasodilatation of retinal arterioles and venules 4 weeks after statin therapy in patients with hypercholesterolaemia indicating pleiotropic effects of statins on the retinal microcirculation which seem to be mediated by the endothelium-dependent, NO-mediated pathway. © 2011 The Authors. Acta Ophthalmologica © 2011 Acta Ophthalmologica Scandinavica Foundation.

Correlation of Retinal Nerve Fiber Layer Thickness and Visual Fields in Glaucoma: A broken stick model

PubMed Central

Alasil, Tarek; Wang, Kaidi; Yu, Fei; Field, Matthew G.; Lee, Hang; Baniasadi, Neda; de Boer, Johannes F.; Coleman, Anne L.; Chen, Teresa C.

2015-01-01

Purpose To determine the retinal nerve fiber layer (RNFL) thickness at which visual field (VF) damage becomes detectable and associated with structural loss. Design Retrospective cross-sectional study. Methods Eighty seven healthy and 108 glaucoma subjects (one eye per subject) were recruited from an academic institution. All patients had VF examinations (Swedish Interactive Threshold Algorithm 24-2 test of the Humphrey visual field analyzer 750i; Carl Zeiss Meditec, Dublin, CA) and spectral domain optical coherence tomography RNFL scans (Spectralis, Heidelberg Engineering, Heidelberg, Germany). Comparison of RNFL thicknesses values with VF threshold values showed a plateau of VF threshold values at high RNFL thickness values and then a sharp decrease at lower RNFL thickness values. A broken stick statistical analysis was utilized to estimate the tipping point at which RNFL thickness values are associated with VF defects. The slope for the association between structure and function was computed for data above and below the tipping point. Results The mean RNFL thickness value that was associated with initial VF loss was 89 μm. The superior RNFL thickness value that was associated with initial corresponding inferior VF loss was 100 μm. The inferior RNFL thickness value that was associated with initial corresponding superior VF loss was 73 μm. The differences between all the slopes above and below the aforementioned tipping points were statistically significant (p<0.001). Conclusions In open angle glaucoma, substantial RNFL thinning or structural loss appears to be necessary before functional visual field defects become detectable. PMID:24487047

The Relationship of Retinal Vessel Diameters and Fractal Dimensions with Blood Pressure and Cardiovascular Risk Factors

PubMed Central

Li, Qiaowei; Yuan, Yin; Gao, Zhonghai; Chen, Falin

2014-01-01

Background This study aimed to investigate the correlation between quantitative retinal vascular parameters such as central retinal arteriolar equivalent (CRAE) and retinal vascular fractal dimension (D(f)), and cardiovascular risk factors in the Chinese Han population residing in the in islands of southeast China. Methodology/Principle Findings In this cross-sectional study, fundus photographs were collected and semi-automated analysis software was used to analyze retinal vessel diameters and fractal dimensions. Cardiovascular risk factors such as relevant medical history, blood pressure (BP), lipids, and blood glucose data were collected. Subjects had a mean age of 51.9±12.0 years and included 812 (37.4%) males and 1,357 (62.6%) females. Of the subjects, 726 (33.5%) were overweight, 226 (10.4%) were obese, 272 (12.5%) had diabetes, 738 (34.0%) had hypertension, and 1,156 (53.3%) had metabolic syndrome. After controlling for the effects of potential confounders, multivariate analyses found that age (β = 0.06, P = 0.008), sex (β = 1.33, P = 0.015), mean arterial blood pressure (β = −0.12, P<0.001), high-sensitivity C-reactive protein (β = −0.22, P = 0.008), and CRVE (β = 0.23, P<0.001) were significantly associated with CRAE. Age (β = −0.0012, P<0.001), BP classification (prehypertension: β = −0.0075, P = 0.014; hypertension: β = −0.0131, P = 0.002), and hypertension history (β = −0.0007, P = 0.009) were significantly associated with D(f). Conclusions/Significance D(f) exhibits a stronger association with BP than CRAE. Thus, D(f) may become a useful indicator of cardiovascular risk. PMID:25188273

Obtaining optic disc center and pixel region by automatic thresholding methods on morphologically processed fundus images.

PubMed

Marin, Diego; Gegundez-Arias, Manuel E; Suero, Angel; Bravo, Jose M

2015-02-01

Development of automatic retinal disease diagnosis systems based on retinal image computer analysis can provide remarkably quicker screening programs for early detection. Such systems are mainly focused on the detection of the earliest ophthalmic signs of illness and require previous identification of fundal landmark features such as optic disc (OD), fovea or blood vessels. A methodology for accurate center-position location and OD retinal region segmentation on digital fundus images is presented in this paper. The methodology performs a set of iterative opening-closing morphological operations on the original retinography intensity channel to produce a bright region-enhanced image. Taking blood vessel confluence at the OD into account, a 2-step automatic thresholding procedure is then applied to obtain a reduced region of interest, where the center and the OD pixel region are finally obtained by performing the circular Hough transform on a set of OD boundary candidates generated through the application of the Prewitt edge detector. The methodology was evaluated on 1200 and 1748 fundus images from the publicly available MESSIDOR and MESSIDOR-2 databases, acquired from diabetic patients and thus being clinical cases of interest within the framework of automated diagnosis of retinal diseases associated to diabetes mellitus. This methodology proved highly accurate in OD-center location: average Euclidean distance between the methodology-provided and actual OD-center position was 6.08, 9.22 and 9.72 pixels for retinas of 910, 1380 and 1455 pixels in size, respectively. On the other hand, OD segmentation evaluation was performed in terms of Jaccard and Dice coefficients, as well as the mean average distance between estimated and actual OD boundaries. Comparison with the results reported by other reviewed OD segmentation methodologies shows our proposal renders better overall performance. Its effectiveness and robustness make this proposed automated OD location and segmentation method a suitable tool to be integrated into a complete prescreening system for early diagnosis of retinal diseases. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

RETINAL VASCULAR PATHOLOGY RISK DEVELOPMENT IN THE IRRADIATED AT DIFFERENT AGES AS A RESULT OF CHERNOBYL NPP ACCIDENT.

PubMed

Fedirko, P A; Babenko, T F; Dorichevska, R Yu; Garkava, N A

2015-12-01

To assess the relationship between the age at which a person undergoes radiation exposure and risk of developing eye lesions (case study of the retinal angiopathy prevalence). The object of the study was the state of the retinal vessels in 2,531 persons (1,948 evacuated from the city of Pripyat under the age of 20 and 583 exposed to radiation in utero as a result of the Chernobyl NPP disaster. The results of standardized ophthalmic examination conducted from 1993 to 2000 within the framework of Clinical and epidemiological registry are used for the analysis. The evacuees were subdivided into different age groups of the exposed to radiation. The cohort of control group formed corresponding age groups of the unirradiated control. Statistical analysis of the survey results was carried out using the free trial version of «Open Epi 2.2.1» software package. The results obtained revealed a significant prevalence of retinal vessels pathology in all groups. The difference in angiopathy prevalence in exposed in utero persons was significant compared to age-control. The prevalence of retinal vascular pathology was also significantly higher in all groups of evacuees. Angiopathy prevalence was higher in the group exposed in utero and at the age of 8-12 years, and in the group of people who were exposed at the age of 4-7 years, the risk of angiopathy was lower. It is proved that the occurrence of distant radiation effects mainly depends on the age at which a person has undergone irradiation. It should be noted that all the other conditions were approximately the same. If working conditions of the persons who were exposed in utero or were aged 8 to 20 years when the Chernobyl disaster happened are connected with occupational radiation exposure it is necessary to take additional preventive measures. P. А. Fedirko, T. F. Babenko, R. Yu. Dorichevska, N. А. Garkava.

Characteristics of Hyperautofluorescent Choroidal Vessels Using Fundus Camera Type Short-Wavelength Autofluorescence.

PubMed

Shinojima, Ari; Mori, Ryusaburo; Nakashizuka, Hiroyuki; Shimada, Hiroyuki

2016-01-01

To clarify differences between eyes showing hyperautofluorescent choroidal vessels in both nasal and temporal, or only the nasal, portions of the fundus using fundus autofluorescence. Nineteen eyes with hyperautofluorescent vessels in both nasal and temporal portions (group 1) and 17 only the nasal portion (group 2) of the fundus were studied. Choroidal and retinal thicknesses (foveal, and nasal and temporal 3,000 µm from the fovea), axial length, and refraction were compared between the two groups. In group 1, the average foveal, nasal, and temporal choroidal thicknesses (mean ± SD) were 69.0 ± 30.9, 57.1 ± 18.7, and 88.3 ± 30.4 μm, retinal thicknesses 170.1 ± 48.5, 221.9 ± 46.5, and 209.5 ± 37.9 μm, axial length 28.2 ± 2.2 mm, and refraction -9.9 ± 5.9 dpt. In group 2, the respective values were 174.8 ± 43.0, 80.5 ± 20.9, and 173.5 ± 46.1 μm, 213.4 ± 29.8, 278.3 ± 20.2, and 252.8 ± 19.6 μm, 24.2 ± 1.4 mm, and -1.8 ± 3.8 dpt. There were significant between-group differences for all items (p < 0.05). Fundus autofluorescence tends to be associated with the detection of hyperautofluorescent choroidal vessels in eyes with strong myopia or greater axial length. © 2016 S. Karger AG, Basel.

Lutein facilitates physiological revascularization in a mouse model of retinopathy of prematurity.

PubMed

Fu, Zhongjie; Meng, Steven S; Burnim, Samuel B; Smith, Lois Eh; Lo, Amy Cy

2017-07-01

Retinopathy of prematurity is one of the leading causes of childhood blindness worldwide, with vessel growth cessation and vessel loss in phase I followed by neovascularization in phase II. Ischaemia contributes to its pathogenesis, and lutein protects against ischaemia-induced retinal damages. We aimed to investigate the effects of lutein on a murine model of oxygen-induced retinopathy. Mouse pups were exposed to 75% oxygen for 5 days and returned to room air for another 5 days. Vascular obliteration, neovascularization and blood vessel leakage were examined. Immunohistochemistry for glial cells and microglia were performed. Compared with vehicle controls, mouse pups receiving lutein treatment displayed smaller central vaso-obliterated area and reduced blood vessel leakage. No significant difference in neovascular area was found between lutein and vehicle controls. Lutein promoted endothelial tip cell formation and maintained the astrocytic template in the avascular area in oxygen-induced retinopathy. No significant changes in Müller cell gliosis and microglial activation in the central avascular area were found in lutein-treated pups. Our observations indicated that lutein significantly promoted normal retinal vascular regrowth in the central avascular area, possibly through promoting endothelial tip cell formation and preserving astrocytic template. Our results indicated that lutein might be considered as a supplement for the treatment of proliferative retinopathy of prematurity because of its role in facilitating the revascularization of normal vasculature. © 2016 Royal Australian and New Zealand College of Ophthalmologists.

Retinal oxygen extraction in individuals with type 1 diabetes with no or mild diabetic retinopathy.

PubMed

Fondi, Klemens; Wozniak, Piotr A; Howorka, Kinga; Bata, Ahmed M; Aschinger, Gerold C; Popa-Cherecheanu, Alina; Witkowska, Katarzyna J; Hommer, Anton; Schmidl, Doreen; Werkmeister, René M; Garhöfer, Gerhard; Schmetterer, Leopold

2017-08-01

The aim of this study was to compare retinal oxygen extraction in individuals with diabetes with no or mild non-proliferative diabetic retinopathy and healthy age- and sex-matched volunteers. A total of 24 participants with type 1 diabetes and 24 healthy age- and sex-matched volunteers were included in this cross-sectional study. Retinal oxygen extraction was measured by combining total retinal blood flow measurements using a custom-built bi-directional Doppler optical coherence tomography system with measurements of oxygen saturation using spectroscopic reflectometry. Based on previously published mathematical modelling, the oxygen content in retinal vessels and total retinal oxygen extraction were calculated. Total retinal blood flow was higher in diabetic participants (46.4 ± 7.4 μl/min) than in healthy volunteers (40.4 ± 5.3 μl/min, p = 0.002 between groups). Oxygen content in retinal arteries was comparable between the two groups, but oxygen content in retinal veins was higher in participants with diabetes (0.15 ± 0.02 ml O 2 /ml) compared with healthy control participants (0.13 ± 0.02 ml O 2 /ml, p < 0.001). As such, the arteriovenous oxygen difference and total retinal oxygen extraction were reduced in participants with diabetes compared with healthy volunteers (total retinal oxygen extraction 1.40 ± 0.44 vs 1.70 ± 0.47 μl O 2 /min, respectively, p = 0.03). Our data indicate early retinal hypoxia in individuals with type 1 diabetes with no or mild diabetic retinopathy as compared with healthy control individuals. Further studies are required to fully understand the potential of the technique in risk stratification and treatment monitoring. ClinicalTrials.gov NCT01843114.

Intravitreal ranibizumab may induce retinal arteriolar vasoconstriction in patients with neovascular age-related macular degeneration.

PubMed

Papadopoulou, Domniki N; Mendrinos, Efstratios; Mangioris, Georgios; Donati, Guy; Pournaras, Constantin J

2009-09-01

To study the effect of intravitreal (IVT) ranibizumab (Lucentis; Genentech, Inc, San Francisco, CA) on the retinal arteriolar diameter in patients with neovascular age-related macular degeneration (AMD). Prospective consecutive interventional case series. Eleven eyes of eleven patients with previously untreated neovascular AMD. All eyes had 3 monthly IVT injections of ranibizumab. The diameter of the retinal arterioles was measured in vivo with a retinal vessel analyzer (RVA) before the first IVT injection and then 7 and 30 days after the first, second, and third injections. Primary end points were changes in retinal arteriolar diameter and mean arterial pressure (MAP) after IVT ranibizumab. Secondary end points were changes in best-corrected visual acuity (BCVA), central retinal thickness, and intraocular pressure after IVT ranibizumab, and appearance of adverse events during the follow-up period. A significant decrease of the retinal arteriolar diameter was observed after each IVT injection of ranibizumab. Thirty days after the first, second, and third injections, there was a mean decrease of 8.1+/-3.2%, 11.5+/-4.4%, and 17.6+/-7.4%, respectively, of the retinal arteriolar diameter compared with baseline values (P<0.01). There was no significant change in MAP during the period of follow-up (P>0.05). Thirty days after the third IVT injection of ranibizumab, mean BCVA improved by 6.5+/-4.9 Early Treatment Diabetic Retinopathy Study (ETDRS) letters, and central retinal thickness decreased by 91+/-122 microm (P = 0.03). These results suggest that IVT ranibizumab may induce retinal arteriolar vasoconstriction in patients with neovascular AMD after IVT ranibizumab. Further studies evaluating larger sample sizes are needed to confirm these results and potential adverse effects on the retinal circulation in patients with AMD and retinal vascular diseases. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

The abortive form of Bourneville-Pringle syndrome.

PubMed

Giusti, C

2002-01-01

To present a 26-year-old woman affected by the abortive form of Bourneville-Pringle syndrome. To our knowledge, this disease is unusual since only very few cases have been reported in the scientific literature at this time. Visual acuity was 20/20 in both eyes. No relevant ocular abnormalities were observed excepting two retinal hamartomas, a smaller one in the nasal midperiphery of the right eye and a larger one located along the super-temporal retinal vessels of the left eye. Classical signs of Bourneville-Pringle disease, such as mental retardation and epilepsy, were absent whereas a slight facial adenoma sebaceum and renal cysts represented the solely systemic manifestations of the disease. This case report confirms that retinal phakomata are a typical manifestation of Tuberous Sclerosis, even in the absence of a detected involvement of the brain.

Quantification of the progression of CMV infection as observed from retinal angiograms in patients with AIDS

NASA Astrophysics Data System (ADS)

Brahmi, Djamel; Cassoux, Nathalie; Serruys, Camille; Giron, Alain; Lehoang, Phuc; Fertil, Bernard

1999-05-01

To support ophthalmologists in their daily routine and enable the quantitative assessment of progression of Cytomegalovirus infection as observed on series of retinal angiograms, a methodology allowing an accurate comparison of retinal borders has been developed. In order to evaluate accuracy of borders, ophthalmologists have been asked to repeatedly outline boundaries between infected and noninfected areas. As a matter of fact, accuracy of drawing relies on local features such as contrast, quality of image, background..., all factors which make the boundaries more or less perceptible from one part of an image to another. In order to directly estimate accuracy of retinal border from image analysis, an artificial neural network (a succession of unsupervised and supervised neural networks) has been designed to correlate accuracy of drawing (as calculated form ophthalmologists' hand-outlines) with local features of the underlying image. Our method has been applied to the quantification of CMV retinitis. It is shown that accuracy of border is properly predicted and characterized by a confident envelope that allows, after a registration phase based on fixed landmarks such as vessel forks, to accurately assess the evolution of CMV infection.

Antiangiogenic Therapy for Ischemic Retinopathies

PubMed Central

Al-Latayfeh, Motasem; Silva, Paolo S.; Sun, Jennifer K.; Aiello, Lloyd Paul

2012-01-01

Neovascularization is a common pathological process in various retinal vascular disorders including diabetic retinopathy (DR), age-related macular degeneration (AMD) and retinal vein occlusion (RVO). The development of neovascular vessels may lead to complications such as vitreous hemorrhage, fibrovascular tissue formation, and traction retinal detachments. Ultimately, irreversible vision loss may result. Various proangiogenic factors are involved in these complex processes. Different antiangiogenic drugs have been formulated in an attempt treat these vascular disorders. One factor that plays a major role in the development of retinal neovascularization is vascular endothelial growth factor (VEGF). Anti-VEGF agents are currently FDA approved for the treatment of AMD and RVO. They are also extensively used as an off-label treatment for diabetic macular edema (DME), proliferative DR, and neovascular glaucoma. However, at this time, the long-term safety of chronic VEGF inhibition has not been extensively evaluated. A large and rapidly expanding body of research on angiogenesis is being conducted at multiple centers across the globe to determine the exact contributions and interactions among a variety of angiogenic factors in an effort to determine the therapeutic potential of antiangiogenic agent in the treatment of a variety of retinal diseases. PMID:22675660

Comparison of amplitude-decorrelation, speckle-variance and phase-variance OCT angiography methods for imaging the human retina and choroid

PubMed Central

Gorczynska, Iwona; Migacz, Justin V.; Zawadzki, Robert J.; Capps, Arlie G.; Werner, John S.

2016-01-01

We compared the performance of three OCT angiography (OCTA) methods: speckle variance, amplitude decorrelation and phase variance for imaging of the human retina and choroid. Two averaging methods, split spectrum and volume averaging, were compared to assess the quality of the OCTA vascular images. All data were acquired using a swept-source OCT system at 1040 nm central wavelength, operating at 100,000 A-scans/s. We performed a quantitative comparison using a contrast-to-noise (CNR) metric to assess the capability of the three methods to visualize the choriocapillaris layer. For evaluation of the static tissue noise suppression in OCTA images we proposed to calculate CNR between the photoreceptor/RPE complex and the choriocapillaris layer. Finally, we demonstrated that implementation of intensity-based OCT imaging and OCT angiography methods allows for visualization of retinal and choroidal vascular layers known from anatomic studies in retinal preparations. OCT projection imaging of data flattened to selected retinal layers was implemented to visualize retinal and choroidal vasculature. User guided vessel tracing was applied to segment the retinal vasculature. The results were visualized in a form of a skeletonized 3D model. PMID:27231598

Type 3 Neovascularization Associated with Retinitis Pigmentosa.

PubMed

Sayadi, Jihene; Miere, Alexandra; Souied, Eric H; Cohen, Salomon Y

2017-01-01

To report a case of type 3 neovascular lesion in a patient with retinitis pigmentosa (RP) complicated by macular edema. A 78-year-old man with a long follow-up for RP was referred for painless visual acuity decrease in the right eye. Best-corrected visual acuity was 20/125 in the right eye and 20/40 in the left. Fundus examination showed typical RP and macular edema in both eyes. In the right eye, spectral domain optical coherence tomography revealed a marked cystic macular edema associated with disruption of the Bruch membrane/retinal pigment epithelium complex overlying a pigmentary epithelium detachment, with a vascular structure which appeared to originate from the deep capillary plexus and to be connected with the subretinal pigment epithelium space. Optical coherence tomography angiography showed a high-flow vessel infiltrating the outer retinal layers in the deep capillary plexus segmentation, and a tuft-shaped, bright, high-flow network that seemed to be connected with the subretinal pigment epithelium space in the outer retinal layer segmentation. This presentation was consistent with an early type 3 neovascular lesion in the right eye. Type 3 neovascularization may be considered a possible complication of RP.

Cystoid edema, neovascularization and inflammatory processes in the murine Norrin-deficient retina.

PubMed

Beck, Susanne C; Karlstetter, Marcus; Garcia Garrido, Marina; Feng, Yuxi; Dannhausen, Katharina; Mühlfriedel, Regine; Sothilingam, Vithiyanjali; Seebauer, Britta; Berger, Wolfgang; Hammes, Hans-Peter; Seeliger, Mathias W; Langmann, Thomas

2018-04-13

Mutations in the Norrin (NDP) gene cause severe developmental blood vessel defects in the retina leading to congenital blindness. In the retina of Ndph-knockout mice only the superficial capillary network develops. Here, a detailed characterization of this mouse model at late stages of the disease using in vivo retinal imaging revealed cystoid structures that closely resemble the ovoid cysts in the inner nuclear layer of the human retina with cystoid macular edema (CME). In human CME an involvement of Müller glia cells is hypothesized. In Ndph-knockout retinae we could demonstrate that activated Müller cells were located around and within these cystoid spaces. In addition, we observed extensive activation of retinal microglia and development of neovascularization. Furthermore, ex vivo analyses detected extravasation of monocytic cells suggesting a breakdown of the blood retina barrier. Thus, we could demonstrate that also in the developmental retinal vascular pathology present in the Ndph-knockout mouse inflammatory processes are active and may contribute to further retinal degeneration. This observation delivers a new perspective for curative treatments of retinal vasculopathies. Modulation of inflammatory responses might reduce the symptoms and improve visual acuity in these diseases.