Science.gov

Sample records for 11-cis 4-oh retinal

  1. Effects of Infrared Laser Radiation on the In Vitro Isomerization of All-Trans Retinal to 11-Cis Retinal

    PubMed Central

    Liegner, J.; Taboada, J.; Tsin, A. T. C.

    2015-01-01

    The in vitro effect of infrared laser light on the isomerization of all-trans retinal dissolved in an ether/hexane and also an ethanol solvent was studied. Pulsed laser energy at 1064 nm was used to drive the molecular reconfiguration of all-trans retinal to 11-cis retinal. High pressure liquid chromatography (HPLC) was used to quantify the conversion. Overall isomerization was minimal (0.2 percent to 1.0 percent), yet, a significant difference in isomerization due to pulsed infrared laser energy over non-modulated monochromatic laser light was detected (up to 168 percent difference). Potentially, pulsed laser radiation tuned to the ethylenic stretch frequency of the C11=C12 bond of retinal may induce rotational changes to the chromophore. PMID:26321787

  2. ATP-binding cassette transporter ABCA4 and chemical isomerization protect photoreceptor cells from the toxic accumulation of excess 11-cis-retinal

    PubMed Central

    Quazi, Faraz; Molday, Robert S.

    2014-01-01

    The visual cycle is a series of enzyme-catalyzed reactions which converts all-trans-retinal to 11-cis-retinal for the regeneration of visual pigments in rod and cone photoreceptor cells. Although essential for vision, 11-cis-retinal like all-trans-retinal is highly toxic due to its highly reactive aldehyde group and has to be detoxified by either reduction to retinol or sequestration within retinal-binding proteins. Previous studies have focused on the role of the ATP-binding cassette transporter ABCA4 associated with Stargardt macular degeneration and retinol dehydrogenases (RDH) in the clearance of all-trans-retinal from photoreceptors following photoexcitation. How rod and cone cells prevent the accumulation of 11-cis-retinal in photoreceptor disk membranes in excess of what is required for visual pigment regeneration is not known. Here we show that ABCA4 can transport N-11-cis-retinylidene-phosphatidylethanolamine (PE), the Schiff-base conjugate of 11-cis-retinal and PE, from the lumen to the cytoplasmic leaflet of disk membranes. This transport function together with chemical isomerization to its all-trans isomer and reduction to all-trans-retinol by RDH can prevent the accumulation of excess 11-cis-retinal and its Schiff-base conjugate and the formation of toxic bisretinoid compounds as found in ABCA4-deficient mice and individuals with Stargardt macular degeneration. This segment of the visual cycle in which excess 11-cis-retinal is converted to all-trans-retinol provides a rationale for the unusually high content of PE and its long-chain unsaturated docosahexaenoyl group in photoreceptor membranes and adds insight into the molecular mechanisms responsible for Stargardt macular degeneration. PMID:24707049

  3. Biochemical Measurements of Free Opsin in Macular Degeneration Eyes: Examining the 11-CIS Retinal Deficiency Hypothesis of Delayed Dark Adaptation (An American Ophthalmological Society Thesis).

    PubMed

    Hanneken, Anne; Neikirk, Thomas; Johnson, Jennifer; Kono, Masahiro

    2017-08-01

    To test the hypothesis that delayed dark adaptation in patients with macular degeneration is due to an excess of free unliganded opsin (apo-opsin) and a deficiency of the visual chromophore, 11 -cis retinal, in rod outer segments. A total of 50 human autopsy eyes were harvested from donors with and without macular degeneration within 2-24 hrs. postmortem. Protocols were developed which permitted dark adaptation of normal human eyes after death and enucleation. Biochemical methods of purifying rod outer segments were optimized and the concentration of rhodopsin and apo-opsin was measured with UV-visible scanning spectroscopy. The presence of apo-opsin was calculated by measuring the difference in the rhodopsin absorption spectra before and after the addition of 11 -cis retinal. A total of 20 normal eyes and 16 eyes from donors with early, intermediate and advanced stages of macular degeneration were included in the final analysis. Dark adaptation was achieved by harvesting whole globes in low light, transferring into dark (light-proof) canisters and dissecting the globes using infrared light and image converters for visualization. Apo-opsin was readily detected in positive controls after the addition of 11 -cis retinal. Normal autopsy eyes showed no evidence of apo-opsin. Eyes with macular degeneration also showed no evidence of apo-opsin, regardless of the severity of disease. Methods have been developed to study dark adaptation in human autopsy eyes. Eyes with age-related macular degeneration do not show a deficiency of 11 -cis retinal or an excess of apo-opsin within rod outer segments.

  4. Biochemical Measurements of Free Opsin in Macular Degeneration Eyes: Examining the 11-CIS Retinal Deficiency Hypothesis of Delayed Dark Adaptation (An American Ophthalmological Society Thesis)

    PubMed Central

    Hanneken, Anne; Neikirk, Thomas; Johnson, Jennifer; Kono, Masahiro

    2017-01-01

    Purpose To test the hypothesis that delayed dark adaptation in patients with macular degeneration is due to an excess of free unliganded opsin (apo-opsin) and a deficiency of the visual chromophore, 11-cis retinal, in rod outer segments. Methods A total of 50 human autopsy eyes were harvested from donors with and without macular degeneration within 2–24 hrs. postmortem. Protocols were developed which permitted dark adaptation of normal human eyes after death and enucleation. Biochemical methods of purifying rod outer segments were optimized and the concentration of rhodopsin and apo-opsin was measured with UV-visible scanning spectroscopy. The presence of apo-opsin was calculated by measuring the difference in the rhodopsin absorption spectra before and after the addition of 11-cis retinal. Results A total of 20 normal eyes and 16 eyes from donors with early, intermediate and advanced stages of macular degeneration were included in the final analysis. Dark adaptation was achieved by harvesting whole globes in low light, transferring into dark (light-proof) canisters and dissecting the globes using infrared light and image converters for visualization. Apo-opsin was readily detected in positive controls after the addition of 11-cis retinal. Normal autopsy eyes showed no evidence of apo-opsin. Eyes with macular degeneration also showed no evidence of apo-opsin, regardless of the severity of disease. Conclusions Methods have been developed to study dark adaptation in human autopsy eyes. Eyes with age-related macular degeneration do not show a deficiency of 11-cis retinal or an excess of apo-opsin within rod outer segments. PMID:28900371

  5. Protein Field Effect on the Dark State of 11-cisRetinal in Rhodopsin by Quantum Monte Carlo/Molecular Mechanics.

    PubMed

    Coccia, Emanuele; Varsano, Daniele; Guidoni, Leonardo

    2013-01-08

    The accurate determination of the geometrical details of the dark state of 11- cis retinal in rhodopsin represents a fundamental step for the rationalization of the protein role in the optical spectral tuning in the vision mechanism. We have calculated geometries of the full retinal protonated Schiff base chromophore in the gas phase and in the protein environment using the correlated variational Monte Carlo method. The bond length alternation of the conjugated carbon chain of the chromophore in the gas phase shows a significant reduction when moving from the β -ionone ring to the nitrogen, whereas, as expected, the protein environment reduces the electronic conjugation. The proposed dark state structure is fully compatible with solid-state NMR data reported by Carravetta et al. [ J. Am. Chem. Soc . 2004 , 126 , 3948-3953]. TDDFT/B3LYP calculations on such geometries show a blue opsin shift of 0.28 and 0.24 eV induced by the protein for S 1 and S 2 states, consistently with literature spectroscopic data. The effect of the geometrical distortion alone is a red shift of 0.21 and 0.16 eV with respect to the optimized gas phase chromophore. Our results open new perspectives for the study of the properties of chromophores in their biological environment using correlated methods.

  6. The role of 11-cis-retinyl esters in vertebrate cone vision.

    PubMed

    Babino, Darwin; Perkins, Brian D; Kindermann, Aljoscha; Oberhauser, Vitus; von Lintig, Johannes

    2015-01-01

    A cycle of cis-to-trans isomerization of the chromophore is intrinsic to vertebrate vision where rod and cone photoreceptors mediate dim- and bright-light vision, respectively. Daylight illumination can greatly exceed the rate at which the photoproduct can be recycled back to the chromophore by the canonical visual cycle. Thus, an additional supply pathway(s) must exist to sustain cone-dependent vision. Two-photon microscopy revealed that the eyes of the zebrafish (Danio rerio) contain high levels of 11-cis-retinyl esters (11-REs) within the retinal pigment epithelium. HPLC analyses demonstrate that 11-REs are bleached by bright light and regenerated in the dark. Pharmacologic treatment with all-trans-retinylamine (Ret-NH2), a potent and specific inhibitor of the trans-to-cis reisomerization reaction of the canonical visual cycle, impeded the regeneration of 11-REs. Intervention with 11-cis-retinol restored the regeneration of 11-REs in the presence of all-trans-Ret-NH2. We used the XOPS:mCFP transgenic zebrafish line with a functional cone-only retina to directly demonstrate that this 11-RE cycle is critical to maintain vision under bright-light conditions. Thus, our analyses reveal that a dark-generated pool of 11-REs helps to supply photoreceptors with the chromophore under the varying light conditions present in natural environments. © FASEB.

  7. In vivo isomerization of all-trans- to 11-cis-retinoids in the eye occurs at the alcohol oxidation state

    SciTech Connect

    Bernstein, P.S.; Rando, R.R.

    1986-10-21

    The vertebrate biochemical pathway for regeneration of visual pigments in the living eye after bleaching is largely uncharacterized. Since isomerization of an all-trans-retinoid to an 11-cis-retinoid could conceivably occur via the aldehyde, alcohol, or ester forms of vitamin A, it is important to determine the oxidation state of the retinoid that is isomerized in vivo. To address this problem, light-adapted rats and frogs were injected intraperitoneally with a mixture of (15-/sup 3/H)-all-trans-retinol and (15-/sup 14/C)-all-trans-retinol. After 4 or 24 h of dark adaptation, labeled retinoids in the animal's eyes were analyzed. All rats had the expected 50% loss of /supmore » 3/H label (relative to /sup 14/C) in 11-cis-retinal, a loss of /sup 3/H that must occur when (15-/sup 3/H)retinol is oxidized to retinal. 11-cis-Retinyl esters in the rats' eyes at 4 h retained 67% of the /sup 3/H label, and this could be increased to 81% when the rats were pretreated with 4-methylpyrazole, an alcohol dehydrogenase inhibitor known to inhibit dark adaptation. This result demonstrates that retinoid isomerization occurs at the alcohol oxidation state in the rat eye. Had it occurred at the aldehyde oxidation state, at least 50% of the /sup 3/H in the 11-cis-retinyl esters would have been lost. The importance of this isomerization pathway is emphasized by the observation that dark-adapting rats whose alcohol dehydrogenase(s) had been inhibited by 4-methylpyrazole had increased amounts of 11-cis-retinyl ester in their eyes relative to control rat eyes, a result that is understandable only if retinoids are isomerized in vivo at the alcohol oxidation state.« less

  8. Chicken Retinas Contain a Retinoid Isomerase Activity that Catalyzes the Direct Conversion of all-trans-Retinol to 11-cis-Retinol†

    PubMed Central

    Mata, Nathan L.; Ruiz, Alberto; Radu, Roxana A.; Bui, Tam V.; Travis, Gabriel H.

    2010-01-01

    Vertebrate retinas contain two types of light-detecting cells. Rods subserve vision in dim light, while cones provide color vision in bright light. Both contain light-sensitive proteins called opsins. The light-absorbing chromophore in most opsins is 11-cis-retinaldehyde, which is isomerized to all-trans-retinaldehyde by absorption of a photon. Restoration of light sensitivity requires chemical re-isomerization of retinaldehyde by an enzymatic pathway called the visual cycle in the retinal pigment epithelium. The isomerase in this pathway uses all-trans-retinyl esters synthesized by lecithin retinol acyl transferase (LRAT) as the substrate. Several lines of evidence suggest that cone opsins regenerate by a different mechanism. Here we demonstrate the existence of two catalytic activities in chicken retinas. The first is an isomerase activity that effects interconversion of all-trans-retinol and 11-cis-retinol. The second is an ester synthase that effects palmitoyl coenzyme A-dependent synthesis of all-trans- and 11-cis-retinyl esters. Kinetic analysis of these two activities suggests that they act in concert to drive the formation of 11-cis-retinoids in chicken retinas. These activities may be part of a new visual cycle for the regeneration of chromophores in cones. PMID:16128572

  9. Conditional Ablation of Retinol Dehydrogenase 10 in the Retinal Pigmented Epithelium Causes Delayed Dark Adaption in Mice*

    PubMed Central

    Sahu, Bhubanananda; Sun, Wenyu; Perusek, Lindsay; Parmar, Vipulkumar; Le, Yun-Zheng; Griswold, Michael D.; Palczewski, Krzysztof; Maeda, Akiko

    2015-01-01

    Regeneration of the visual chromophore, 11-cis-retinal, is a crucial step in the visual cycle required to sustain vision. This cycle consists of sequential biochemical reactions that occur in photoreceptor cells and the retinal pigmented epithelium (RPE). Oxidation of 11-cis-retinol to 11-cis-retinal is accomplished by a family of enzymes termed 11-cis-retinol dehydrogenases, including RDH5 and RDH11. Double deletion of Rdh5 and Rdh11 does not limit the production of 11-cis-retinal in mice. Here we describe a third retinol dehydrogenase in the RPE, RDH10, which can produce 11-cis-retinal. Mice with a conditional knock-out of Rdh10 in RPE cells (Rdh10 cKO) displayed delayed 11-cis-retinal regeneration and dark adaption after bright light illumination. Retinal function measured by electroretinogram after light exposure was also delayed in Rdh10 cKO mice as compared with controls. Double deletion of Rdh5 and Rdh10 (cDKO) in mice caused elevated 11/13-cis-retinyl ester content also seen in Rdh5−/−Rdh11−/− mice as compared with Rdh5−/− mice. Normal retinal morphology was observed in 6-month-old Rdh10 cKO and cDKO mice, suggesting that loss of Rdh10 in the RPE does not negatively affect the health of the retina. Compensatory expression of other retinol dehydrogenases was observed in both Rdh5−/− and Rdh10 cKO mice. These results indicate that RDH10 acts in cooperation with other RDH isoforms to produce the 11-cis-retinal chromophore needed for vision. PMID:26391396

  10. Supplementation with vitamin a derivatives to rescue vision in animal models of degenerative retinal diseases.

    PubMed

    Perusek, Lindsay; Maeda, Akiko; Maeda, Tadao

    2015-01-01

    The perception of light begins when photons reach retinal tissue located at the back of the eye and photoisomerize the visual chromophore 11-cis-retinal to all-trans-retinal within photoreceptor cells. Isomerization of 11-cis-retinal activates the protein rhodopsin located in photoreceptor outer segments, thereby inducing a phototransduction cascade leading to visual perception. To maintain vision, 11-cis-retinal is regenerated in the retinal pigmented epithelium (RPE) via the visual cycle and delivered back to the photoreceptor cells where it may again bind to rhodopsin. Distinct pathological mechanisms have been observed to contribute to inherited retinal degenerative diseases including severe delay in 11-cis-retinal regeneration and delayed clearance of all-trans-retinal, which leads to the accumulation of harmful retinoid by-products. In the last decade, our group has conducted several proof-of-concept (POC) studies with retinoid derivatives aimed at developing treatments for retinal degenerative diseases caused by an impaired visual cycle. Here, we will introduce experimental procedures, which have been developed for POC studies involving retinoid biology.

  11. Coupling of Retinal, Protein, and Water Dynamics in Squid Rhodopsin

    PubMed Central

    Jardón-Valadez, Eduardo; Bondar, Ana-Nicoleta; Tobias, Douglas J.

    2010-01-01

    The light-induced isomerization of the retinal from 11-cis to all-trans triggers changes in the conformation of visual rhodopsins that lead to the formation of the activated state, which is ready to interact with the G protein. To begin to understand how changes in the structure and dynamics of the retinal are transmitted to the protein, we performed molecular dynamics simulations of squid rhodopsin with 11-cis and all-trans retinal, and with two different force fields for describing the retinal molecule. The results indicate that structural rearrangements in the binding pocket, albeit small, propagate toward the cytoplasmic side of the protein, and affect the dynamics of internal water molecules. The sensitivity of the active-site interactions on the retinal force-field parameters highlights the coupling between the retinal molecule and its immediate protein environment. PMID:20923654

  12. Vitamin A Derivatives as Treatment Options for Retinal Degenerative Diseases

    PubMed Central

    Perusek, Lindsay; Maeda, Tadao

    2013-01-01

    The visual cycle is a sequential enzymatic reaction for vitamin A, all-trans-retinol, occurring in the outer layer of the human retina and is essential for the maintenance of vision. The central source of retinol is derived from dietary intake of both retinol and pro-vitamin A carotenoids. A series of enzymatic reactions, located in both the photoreceptor outer segment and the retinal pigment epithelium, transform retinol into the visual chromophore 11-cis-retinal, regenerating visual pigments. Retina specific proteins carry out the majority of the visual cycle, and any significant interruption in this sequence of reactions is capable of causing varying degrees of blindness. Among these important proteins are Lecithin:retinol acyltransferase (LRAT) and retinal pigment epithelium-specific 65-kDa protein (RPE65) known to be responsible for esterification of retinol to all-trans-retinyl esters and isomerization of these esters to 11-cis-retinal, respectively. Deleterious mutations in these genes are identified in human retinal diseases that cause blindness, such as Leber congenital amaurosis (LCA) and retinitis pigmentosa (RP). Herein, we discuss the pathology of 11-cis-retinal deficiency caused by these mutations in both animal disease models and human patients. We also review novel therapeutic strategies employing artificial visual chromophore 9-cis-retinoids which have been employed in clinical trials involving LCA patients. PMID:23857173

  13. Synthesis of the suspected trans-11,cis-13 conjugated linoleic acid isomer in ruminant mammary tissue by FADS3-catalyzed Δ13-desaturation of vaccenic acid.

    PubMed

    Garcia, Cyrielle; Duby, Cécile; Catheline, Daniel; Toral, Pablo G; Bernard, Laurence; Legrand, Philippe; Rioux, Vincent

    2017-01-01

    The octadecadienoic conjugated linoleic acid (CLA) isomer with trans-11 and cis-13 double bonds (trans-11,cis-13 CLA) has been described in ruminant milk. For now, this specific CLA is suspected to derive exclusively from ruminal biohydrogenation of dietary α-linolenic acid. However, in rodents, the fatty acid desaturase 3 (FADS3) gene was recently shown to code for an enzyme able to catalyze the unexpected Δ13-desaturation of vaccenic acid, producing a Δ11,13-CLA with all the structural characteristics of the trans-11,cis-13 isomer, although no commercial standard exists for complete conclusive identification. Because the FADS3 gene has already been reported in bovine animals, we hypothesized in the present study that an alternative direct FADS3-catalyzed Δ13-desaturation of vaccenic acid in mammary tissue may therefore co-exist with α-linolenic acid biohydrogenation to explain the final ruminant milk trans-11,cis-13 CLA presence. Here, we first confirm that the FADS3 gene is present in ruminant mammal genomic sequence databases. Second, we demonstrate that the Δ11,13-CLA found in milk fat and the highly probable trans-11,cis-13 CLA isomer produced by rodent FADS3 possess exactly the same structural characteristics. Then, we show that bovine mammary MAC-T and BME-UV epithelial cells express both FADS3 and stearoyl-CoA desaturase 1 (SCD1) mRNA and are able to synthesize both the suspected trans-11,cis-13 CLA and cis-9,trans-11CLA (rumenic acid) isomers when incubated with vaccenic acid. Finally, the concomitant presence of the suspected trans-11,cis-13 CLA isomer with FADS3 mRNA was shown in goat mammary tissue, whereas both were conversely very low or even absent in goat liver. Therefore, this study provides several lines of evidence that, by analogy with rumenic acid, trans-11,cis-13 CLA may originate both from ruminal biohydrogenation and from direct FADS3-catalyzed Δ13-desaturation of vaccenic acid in mammary tissue. Copyright © 2017 American Dairy

  14. Isolation and characterization of a retinal-binding protein from the squid retina.

    PubMed

    Ozaki, K; Terakita, A; Hara, R; Hara, T

    1987-01-01

    A retinal-binding protein (RALBP) was isolated from the squid retina, and purified by anion-exchange and size-exclusion chromatography. The molecular weight was determined to be 51,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by gel filtration. The purified sample showed absorption maxima at about 330 and 400 nm in addition to a protein band, indicating the occurrence of retinol and retinal, respectively. The relative heights of these two peaks varied from preparation to preparation, depending on retinoid ligands. Irradiation of RALBP caused no marked change in absorption, but the amount of 11-cis-retinal decreased to form a photosteady state mixture with all-trans- and 13-cis-retinals. RALBP was fairly stable even in the presence of hydroxylamine (100 mM), but was affected by sodium borohydride (30 mM) or borane dimethylamine (400 mM), with the retinal reduced to retinol. When incubated with metaretinochrome-carrying membranes in the dark, RALBP specifically took up 11-cis-retinal and lost all-trans-retinol. Upon further incubation of this RALBP with opsin-containing membranes, rhodopsin was progressively formed in the dark. Squid RALBP may act as a shuttle in transferring the 11-cis-retinal from metaretinochrome to opsin in the visual cells.

  15. Retinitis Pigmentosa

    MedlinePlus

    ... Action You are here Home › Retinal Diseases Listen Retinitis Pigmentosa What is retinitis pigmentosa? What are the symptoms? ... is available? What treatment is available? What is retinitis pigmentosa? Retinitis pigmentosa, also known as RP, refers to ...

  16. Potential Therapeutic Agents Against Retinal Diseases Caused by Aberrant Metabolism of Retinoids.

    PubMed

    Liu, Xin; Chen, Jingmeng; Liu, Zhe; Li, Jie; Yao, Ke; Wu, Yalin

    2016-03-01

    The retinoid (visual) cycle is a complex enzymatic pathway that operates in the retina for the regeneration of 11-cis-retinal (11-cis-Ral), the inherent visual chromophore indispensable for vision. Deficiencies in the retinoid metabolism are involved in pathologic mechanisms of several forms of retinal diseases including age-related macular degeneration, Stargardt's disease, and Leber's congenital amaurosis, for which no effective cures presently exist. Nevertheless, the interference of abnormal retinoid metabolism with chemicals has been considered to be a promising strategy aimed at alleviating these retinal dysfunctions. Moreover, since gene therapy is gaining increasing importance in clinical practice, the modulation of key enzymes implicated with the retinoid cycle at a genetic level will hold great promise for the treatment of patients with degenerative diseases of the retina.

  17. Functional heterogeneity of mutant rhodopsins responsible for autosomal dominant retinitis pigmentosa.

    PubMed Central

    Sung, C H; Schneider, B G; Agarwal, N; Papermaster, D S; Nathans, J

    1991-01-01

    Thirteen mutant rhodopsins responsible for autosomal dominant retinitis pigmentosa (ADRP) have been produced by transfection of cloned cDNA into tissue culture cells. Three mutants [class I: Phe-45----Leu, Gln-344----termination (deletion of C-terminal positions 344-348), and Pro-347----Leu] resemble wild-type rhodopsin in yield, regenerability with 11-cis-retinal, and plasma membrane localization. Ten mutants [class II: Thr-17----Met, Pro-23----His, Thr-58----Arg, Val-87----Asp, Gly-89----Asp, Gly-106----Trp, Arg-135----Leu, Arg-135----Trp, Tyr-178----Cys, and Asp-190----Gly] accumulate to significantly lower levels, regenerate with 11-cis-retinal variably or not at all, and are transported inefficiently to the plasma membrane, remaining primarily in the endoplasmic reticulum. These data suggest that there are at least two distinct biochemical defects associated with different rhodopsin mutants in ADRP. Images PMID:1924344

  18. Systemic Retinaldehyde Treatment Corrects Retinal Oxidative Stress, Rod Dysfunction, and Impaired Visual Performance in Diabetic Mice

    PubMed Central

    Berkowitz, Bruce A.; Kern, Timothy S.; Bissig, David; Patel, Priya; Bhatia, Ankit; Kefalov, Vladimir J.; Roberts, Robin

    2015-01-01

    Purpose Diabetes appears to induce a visual cycle defect because rod dysfunction is correctable with systemic treatment of the visual cycle chromophore 11-cis-retinaldehyde. However, later studies have found no evidence for visual cycle impairment. Here, we further examined whether photoreceptor dysfunction is corrected with 11-cis-retinaldehyde. Because antioxidants correct photoreceptor dysfunction in diabetes, the hypothesis that exogenous visual chromophores have antioxidant activity in the retina of diabetic mice in vivo was tested. Methods Rod function in 2-month-old diabetic mice was evaluated using transretinal electrophysiology in excised retinas and apparent diffusion coefficient (ADC) MRI to measure light-evoked expansion of subretinal space (SRS) in vivo. Optokinetic tracking was used to evaluate cone-based visual performance. Retinal production of superoxide free radicals, generated mostly in rod cells, was biochemically measured with lucigenin. Diabetic mice were systemically treated with a single injection of either 11-cis-retinaldehyde, 9-cis-retinaldehyde (a chromophore surrogate), or all-trans-retinaldehyde (the photoisomerization product of 11-cis-retinaldehyde). Results Consistent with previous reports, diabetes significantly reduced (1) dark-adapted rod photo responses (transretinal recording) by ∼18%, (2) rod-dominated light-stimulated SRS expansion (ADC MRI) by ∼21%, and (3) cone-dominated contrast sensitivity (using optokinetic tracking [OKT]) by ∼30%. Both 11-cis-retinaldehyde and 9-cis-retinaldehyde largely corrected these metrics of photoreceptor dysfunction. Higher-than-normal retinal superoxide production in diabetes by ∼55% was also significantly corrected following treatment with 11-cis-retinaldehyde, 9-cis-retinaldehyde, or all-trans-retinaldehyde. Conclusions Collectively, data suggest that retinaldehydes improve photoreceptor dysfunction in diabetic mice, independent of the visual cycle, via an antioxidant mechanism. PMID

  19. CB1 and CB2 Receptors are Novel Molecular Targets for Tamoxifen and 4OH-Tamoxifen

    PubMed Central

    Prather, Paul L.; FrancisDevaraj, FeAna; Dates, Centdrika R.; Greer, Aleksandra K.; Bratton, Stacie M.; Ford, Benjamin M.; Franks, Lirit N.; Radominska-Pandya, Anna

    2013-01-01

    Tamoxifen (Tam) is classified as a selective estrogen receptor modulator (SERM) and is used for treatment of patients with ER-positive breast cancer. However, it has been shown that Tam and its cytochrome P450-generated metabolite 4-hydroxy-Tam (4OH-Tam) also exhibit cytotoxic effects in ER-negative breast cancer cells. These observations suggest that Tam and 4OH-Tam can produce cytotoxicity via estrogen receptor (ER)-independent mechanism(s) of action. The molecular targets responsible for the ER-independent effects of Tam and its derivatives are poorly understood. Interestingly, similar to Tam and 4OH-Tam, cannabinoids have also been shown to exhibit anti-proliferative and apoptotic effects in ER-negative breast cancer cells, and estrogen can regulate expression levels of cannabinoid receptors (CBRs). Therefore, this study investigated whether CBRs might serve as novel molecular targets for Tam and 4OH-Tam. We report that both compounds bind to CB1 and CB2Rs with moderate affinity (0.9-3 μM). Furthermore, Tam and 4OH-Tam exhibit inverse activity at CB1 and CB2Rs in membrane preparations, reducing basal G-protein activity. Tam and 4OH-Tam also act as CB1/CB2R-inverse agonists to regulate the downstream intracellular effector adenylyl cyclase in intact cells, producing concentration-dependent increases in intracellular cAMP. These results suggest that CBRs are molecular targets for Tam and 4OH-Tam and may contribute to the ER-independent cytotoxic effects reported for these drugs. Importantly, these findings also indicate that Tam and 4OH-Tam might be used as structural scaffolds for development of novel, efficacious, non-toxic cancer drugs acting via CB1 and/or CB2Rs. PMID:24148245

  20. Regeneration of bovine and octopus opsins in situ with natural and artificial retinals

    SciTech Connect

    Koutalos, Y.; Ebrey, T.G.; Tsuda, M.

    1989-03-21

    The authors consider the problem of color regulation in visual pigments for both bovine rhodopsin and octopus rhodopsin. Both pigments have 11-cis-retinal as their chromophore. These rhodopsins were bleached in their native membranes, and the opsins were regenerated with natural and artificial chromophores. Both bovine and octopus opsins were regenerated with the 9-cis- and 11-cis-retinal isomers, but the octopus opsin was additionally regenerated with the 13-cis and all-trans isomers. Titration of the octopus opsin with 11-cis-retinal gave an extinction coefficient for octopus rhodopsin of 27,000 {plus minus} 3,000 M{sup {minus}1} cm{sup {minus}1} at 475 nm. The absorption maxima of bovinemore » artificial pigments formed by regenerating opsin with the 11-cis dihydro series of chromophores support a color regulation model for bovine rhodopsin in which the chromophore-binding site of the protein has two negative charges: one directly hydrogen bonded to the Schiff base nitrogen and another near carbon-13. Formation of octopus artificial pigments with both all-trans and 11-cis dihydro chromophores leads to a similar model for octopus rhodopsin and metarhodopsin: there are two negative charges in the chromophore-binding site, one directly hydrogen bonded to the Schiff base nitrogen and a second near carbon-13. The interaction of this second charge with the chromophore in octopus rhodopsin is weaker than in bovine, while in metarhodopsin it is as strong as in bovine.« less

  1. Cytomegalovirus retinitis

    MedlinePlus

    ... sharing features on this page, please enable JavaScript. Cytomegalovirus (CMV) retinitis is a viral infection of the ... need treatment to prevent its return. Alternative Names Cytomegalovirus retinitis Images Eye CMV retinitis CMV (cytomegalovirus) References ...

  2. Human Cellular Retinaldehyde-Binding Protein Has Secondary Thermal 9-cis-Retinal Isomerase Activity

    PubMed Central

    Bolze, Christin S.; Helbling, Rachel E.; Owen, Robin L.; Pearson, Arwen R.; Pompidor, Guillaume; Dworkowski, Florian; Fuchs, Martin R.; Furrer, Julien; Golczak, Marcin; Palczewski, Krzysztof

    2014-01-01

    Cellular retinaldehyde-binding protein (CRALBP) chaperones 11-cis-retinal to convert opsin receptor molecules into photosensitive retinoid pigments of the eye. We report a thermal secondary isomerase activity of CRALBP when bound to 9-cis-retinal. UV/VIS and 1H-NMR spectroscopy were used to characterize the product as 9,13-dicis-retinal. The X-ray structure of the CRALBP mutant R234W:9-cis-retinal complex at 1.9 Å resolution revealed a niche in the binding-pocket for 9-cis-aldehyde different from that reported for 11-cis-retinal. Combined computational, kinetic, and structural data lead us to propose an isomerization mechanism catalyzed by a network of buried waters. Our findings highlight a specific role of water molecules in both CRALBP-assisted specificity towards 9-cis-retinal and its thermal isomerase activity yielding 9,13-dicis-retinal. Kinetic data from two point mutants of CRALBP support an essential role of Glu202 as the initial proton donor in this isomerization reaction. PMID:24328211

  3. Expansion of first-in-class drug candidates that sequester toxic all-trans-retinal and prevent light-induced retinal degeneration.

    PubMed

    Zhang, Jianye; Dong, Zhiqian; Mundla, Sreenivasa Reddy; Hu, X Eric; Seibel, William; Papoian, Ruben; Palczewski, Krzysztof; Golczak, Marcin

    2015-01-01

    All-trans-retinal, a retinoid metabolite naturally produced upon photoreceptor light activation, is cytotoxic when present at elevated levels in the retina. To lower its toxicity, two experimentally validated methods have been developed involving inhibition of the retinoid cycle and sequestration of excess of all-trans-retinal by drugs containing a primary amine group. We identified the first-in-class drug candidates that transiently sequester this metabolite or slow down its production by inhibiting regeneration of the visual chromophore, 11-cis-retinal. Two enzymes are critical for retinoid recycling in the eye. Lecithin:retinol acyltransferase (LRAT) is the enzyme that traps vitamin A (all-trans-retinol) from the circulation and photoreceptor cells to produce the esterified substrate for retinoid isomerase (RPE65), which converts all-trans-retinyl ester into 11-cis-retinol. Here we investigated retinylamine and its derivatives to assess their inhibitor/substrate specificities for RPE65 and LRAT, mechanisms of action, potency, retention in the eye, and protection against acute light-induced retinal degeneration in mice. We correlated levels of visual cycle inhibition with retinal protective effects and outlined chemical boundaries for LRAT substrates and RPE65 inhibitors to obtain critical insights into therapeutic properties needed for retinal preservation. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

  4. Expansion of First-in-Class Drug Candidates That Sequester Toxic All-Trans-Retinal and Prevent Light-Induced Retinal Degeneration

    PubMed Central

    Zhang, Jianye; Dong, Zhiqian; Mundla, Sreenivasa Reddy; Hu, X. Eric; Seibel, William; Papoian, Ruben

    2015-01-01

    All-trans-retinal, a retinoid metabolite naturally produced upon photoreceptor light activation, is cytotoxic when present at elevated levels in the retina. To lower its toxicity, two experimentally validated methods have been developed involving inhibition of the retinoid cycle and sequestration of excess of all-trans-retinal by drugs containing a primary amine group. We identified the first-in-class drug candidates that transiently sequester this metabolite or slow down its production by inhibiting regeneration of the visual chromophore, 11-cis-retinal. Two enzymes are critical for retinoid recycling in the eye. Lecithin:retinol acyltransferase (LRAT) is the enzyme that traps vitamin A (all-trans-retinol) from the circulation and photoreceptor cells to produce the esterified substrate for retinoid isomerase (RPE65), which converts all-trans-retinyl ester into 11-cis-retinol. Here we investigated retinylamine and its derivatives to assess their inhibitor/substrate specificities for RPE65 and LRAT, mechanisms of action, potency, retention in the eye, and protection against acute light-induced retinal degeneration in mice. We correlated levels of visual cycle inhibition with retinal protective effects and outlined chemical boundaries for LRAT substrates and RPE65 inhibitors to obtain critical insights into therapeutic properties needed for retinal preservation. PMID:25538117

  5. Theoretical prediction of nuclear magnetic shieldings and indirect spin-spin coupling constants in 1,1-, cis-, and trans-1,2-difluoroethylenes

    SciTech Connect

    Nozirov, Farhod, E-mail: teobaldk@gmail.com, E-mail: farhod.nozirov@gmail.com; Stachów, Michał, E-mail: michal.stachow@gmail.com; Kupka, Teobald, E-mail: teobaldk@gmail.com, E-mail: farhod.nozirov@gmail.com

    2014-04-14

    A theoretical prediction of nuclear magnetic shieldings and indirect spin-spin coupling constants in 1,1-, cis- and trans-1,2-difluoroethylenes is reported. The results obtained using density functional theory (DFT) combined with large basis sets and gauge-independent atomic orbital calculations were critically compared with experiment and conventional, higher level correlated electronic structure methods. Accurate structural, vibrational, and NMR parameters of difluoroethylenes were obtained using several density functionals combined with dedicated basis sets. B3LYP/6-311++G(3df,2pd) optimized structures of difluoroethylenes closely reproduced experimental geometries and earlier reported benchmark coupled cluster results, while BLYP/6-311++G(3df,2pd) produced accurate harmonic vibrational frequencies. The most accurate vibrations were obtained using B3LYP/6-311++G(3df,2pd)more » with correction for anharmonicity. Becke half and half (BHandH) density functional predicted more accurate {sup 19}F isotropic shieldings and van Voorhis and Scuseria's τ-dependent gradient-corrected correlation functional yielded better carbon shieldings than B3LYP. A surprisingly good performance of Hartree-Fock (HF) method in predicting nuclear shieldings in these molecules was observed. Inclusion of zero-point vibrational correction markedly improved agreement with experiment for nuclear shieldings calculated by HF, MP2, CCSD, and CCSD(T) methods but worsened the DFT results. The threefold improvement in accuracy when predicting {sup 2}J(FF) in 1,1-difluoroethylene for BHandH density functional compared to B3LYP was observed (the deviations from experiment were −46 vs. −115 Hz)« less

  6. Spectroscopic and calorimetric studies on the interaction between PAMAM G4-OH and 5-fluorouracil in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Buczkowski, Adam; Urbaniak, Pawel; Piekarski, Henryk; Palecz, Bartlomiej

    2017-01-01

    The results of spectroscopic measurements (an increase in solubility, equilibrium dialysis, 1H NMR titration) and calorimetric measurements (isothermal titration ITC) indicate spontaneous (ΔG < 0) binding of 5-fluorouracil molecules by PAMAM G4-OH dendrimer with terminal hydroxyl groups in an aqueous solution. PAMAM G4-OH dendrimer bonds about n = 8 ± 1 molecules of the drug with an equilibrium constant of K = 70 ± 10. The process of saturating the dendrimer active sites by the drug molecules is exothermal (ΔH < 0) and is accompanied by an advantageous change in entropy (ΔS > 0). The parameters of binding 5-fluorouracil by PAMAM G4-OH dendrimer were compared with those of binding this drug by the macromolecules of PAMAM G3-OH and G5-OH.

  7. Zn[BPO4(OH)2]: a zinc borophosphate with the rare moganite-type topology.

    PubMed

    Huang, Ya-Xi; Prots, Yurii; Kniep, Rüdiger

    2008-01-01

    A novel zinc borophosphate Zn[BPO(4)(OH)(2)] with moganite-type topology (a rare polymorph of silica) has been prepared from a mixture of ZnO, B(2)O(3), and P(2)O(5) by hydrothermal treatment at 443 K. The crystal structure was determined from single-crystal X-ray data (orthorhombic, Pbcn (no. 60), a=915.07(3), b=897.22(3), c=1059.19(3) pm, V=869.62(5)x10(6) pm(3), Z=8, R1=0.028, wR2=0.075). The crystal structure comprises unbranched vierer-single borophosphate chains running along [010] and interconnected via ZnO(2)(OH)(2)-tetrahedra by sharing common vertices. The resulting topology of the three-dimensional tetrahedral framework structure is described by the Schläfli symbol (4(2).6(2).8(2))(4.6(4).8)(2). Although showing Zn in a tetrahedral coordination, the title compound does not belong to the group of zincoborophosphates but is a special case of a borophosphate containing vierer single rings of tetrahedra with the sequence Zn-B-Zn-P.

  8. NH(4)OH-KOH pulping mechanisms and kinetics of rice straw.

    PubMed

    Huang, Guolin; Shi, Jeffrey X; Langrish, Tim A G

    2007-04-01

    The mechanisms and kinetics of NH(4)OH-KOH mixture pulping rice straw were studied. When aqueous ammonia was mixed with a small amount of caustic potash (ratio of 1:5), three distinct delignification phases were observed in the pulping process: a bulk delignification phase from the beginning of the cooking period to 100 degrees C, a supplementary delignification phase from 100 degrees C to 155 degrees C lasting a further 45 min, and a residual delignification phase until the end of the cooking period. There were two silica removal phases; the first phase was from the beginning of the cooking period to 100 degrees C and the second phase was from 100 degrees C to the end of the cooking period. The rate of delignification reaction was first order with respect to residual lignin and 0.3 order with respect to [OH(-)]. The silica removal was pseudo-first-order with respect to residual silica and 0.6 order with respect to [OH(-)]. The activation energies of the delignification and removal of silica reactions were 35.6 and 30.9 kJ/mol, respectively.

  9. CB1 and CB2 receptors are novel molecular targets for Tamoxifen and 4OH-Tamoxifen

    SciTech Connect

    Prather, Paul L.; FrancisDevaraj, FeAna; Dates, Centdrika R.

    2013-11-15

    Highlights: •Tamoxifen produces cytotoxicity via estrogen-receptor (ER) independent mechanisms. •Tamoxifen binds to CB1 and CB2 cannabinoid receptors and acts as an inverse agonist. •CB1 and CB2 receptors are novel molecular targets for Tamoxifen. •ER-independent effects for Tamoxifen may be mediated via CB1 and/or CB2 receptors. -- Abstract: Tamoxifen (Tam) is classified as a selective estrogen receptor modulator (SERM) and is used for treatment of patients with ER-positive breast cancer. However, it has been shown that Tam and its cytochrome P450-generated metabolite 4-hydroxy-Tam (4OH-Tam) also exhibit cytotoxic effects in ER-negative breast cancer cells. These observations suggest that Tam and 4OH-Tam canmore » produce cytotoxicity via estrogen receptor (ER)-independent mechanism(s) of action. The molecular targets responsible for the ER-independent effects of Tam and its derivatives are poorly understood. Interestingly, similar to Tam and 4OH-Tam, cannabinoids have also been shown to exhibit anti-proliferative and apoptotic effects in ER-negative breast cancer cells, and estrogen can regulate expression levels of cannabinoid receptors (CBRs). Therefore, this study investigated whether CBRs might serve as novel molecular targets for Tam and 4OH-Tam. We report that both compounds bind to CB1 and CB2Rs with moderate affinity (0.9–3 μM). Furthermore, Tam and 4OH-Tam exhibit inverse activity at CB1 and CB2Rs in membrane preparations, reducing basal G-protein activity. Tam and 4OH-Tam also act as CB1/CB2R-inverse agonists to regulate the downstream intracellular effector adenylyl cyclase in intact cells, producing concentration-dependent increases in intracellular cAMP. These results suggest that CBRs are molecular targets for Tam and 4OH-Tam and may contribute to the ER-independent cytotoxic effects reported for these drugs. Importantly, these findings also indicate that Tam and 4OH-Tam might be used as structural scaffolds for development of novel

  10. Nuclear and magnetic structures and magnetic properties of synthetic brochantite, Cu4(OH)6SO4.

    PubMed

    Vilminot, Serge; Richard-Plouet, Mireille; André, Gilles; Swierczynski, Dariusz; Bourée-Vigneron, Françoise; Kurmoo, Mohamedally

    2006-03-21

    Cu4(OH)6SO4 (1) and Cu4(OD)6SO4 (2) were obtained by hydrothermal syntheses from copper sulfate and sodium hydroxide in H2O and D2O, respectively. They crystallize in the monoclinic system, space group P2(1)/a (14), a = 13.1206(5), b = 9.8551(3), c = 6.0295(2) Angstroms, beta = 103.432(3) degrees, V = 758.3(1) Angstroms(3), Z = 4 and a = 13.1187(5), b = 9.8552(3), c = 6.0293(2) Angstroms, beta = 103.410(3) degrees, V = 758.3(1) Angstroms(3), Z = 4, respectively. They are iso-structural to the mineral brochantite and consist of double chains of edge-sharing copper octahedra that are connected to one another by corners to form corrugated planes along bc; these planes are in-turn bridged by the unprecedented mu7-sulfate tetrahedra to give a 3D-structure. All the hydrogen atoms were precisely located from refinement of the neutron powder diffraction data of the deuterated sample. Magnetic susceptibility data reveal a low-dimensional behavior at high temperature and the presence of both ferromagnetic and antiferromagnetic super-exchanges resulting in a 3D long-range antiferromagnetic ordering at 7.5 K accompanied by a small canting of the moments. The transition is confirmed by a lambda-peak in the specific heat. The magnetic structure at 1.4 K shows the moments are oriented perpendicular to the corrugated planes with alternation along +/-a for neighboring chains within the double chains. The enhanced incoherent scattering at low-angle suggests the existence of short-range ferromagnetic clusters.

  11. Retinitis Pigmentosa.

    ERIC Educational Resources Information Center

    Carr, Ronald E.

    1979-01-01

    The author describes the etiology of retinitis pigmentosa, a visual dysfunction which results from progressive loss of the retinal photoreceptors. Sections address signs and symptoms, ancillary findings, heredity, clinical diagnosis, therapy, and research. (SBH)

  12. Retinal Diseases

    MedlinePlus

    ... Linked Retinoschisis (XLRS) X-Linked Retinitis Pigmentosa (XLRP) Usher Syndrome Other Retinal Diseases Glossary News & Research News & Research ... central portion of the retina called the macula. Usher Syndrome Usher syndrome is an inherited condition characterized by ...

  13. Retinal Detachment

    MedlinePlus

    ... is to “conduct and support research, training, health information dissemination, and other programs with respect to blinding eye ... of vision. A retinal detachment is a medical emergency. Anyone experiencing the symptoms of a retinal detachment ...

  14. Retinal Detachment

    MedlinePlus

    ... reading, driving, and seeing fine detail. A retinal detachment lifts or pulls the retina from its normal ... and whites more than African Americans. A retinal detachment is also more likely to occur in people ...

  15. The Retinal Pigment Epithelium: Something More than a Constituent of the Blood-Retinal Barrier—Implications for the Pathogenesis of Diabetic Retinopathy

    PubMed Central

    Simó, Rafael; Villarroel, Marta; Corraliza, Lídia; Hernández, Cristina; Garcia-Ramírez, Marta

    2010-01-01

    The retinal pigment epithelium (RPE) is an specialized epithelium lying in the interface between the neural retina and the choriocapillaris where it forms the outer blood-retinal barrier (BRB). The main functions of the RPE are the following: (1) transport of nutrients, ions, and water, (2) absorption of light and protection against photooxidation, (3) reisomerization of all-trans-retinal into 11-cis-retinal, which is crucial for the visual cycle, (4) phagocytosis of shed photoreceptor membranes, and (5) secretion of essential factors for the structural integrity of the retina. An overview of these functions will be given. Most of the research on the physiopathology of diabetic retinopathy has been focused on the impairment of the neuroretina and the breakdown of the inner BRB. By contrast, the effects of diabetes on the RPE and in particular on its secretory activity have received less attention. In this regard, new therapeutic strategies addressed to modulating RPE impairment are warranted. PMID:20182540

  16. Magnetic excitations from an S=1/2 diamond-shaped tetramer compound Cu 2PO 4OH

    DOE PAGES

    Matsuda, Masaaki; Dissanayake, Sachith E.; Abernathy, Douglas L.; ...

    2015-11-30

    Inelastic neutron scattering experiments have been carried out on a powder sample of Cu 2PO 4OH, which consists of diamond-shaped tetramer spin units with S=1/2. We have observed two nearly dispersionless magnetic excitations at E 1 ~2 and E 2 ~0 meV, whose energy width are broader than the instrumental resolution. The simplest square tetramer model with one dominant interaction, which predicts two sharp excitation peaks at E 1 and E 2(=2E 1), does not explain the experimental result. We found that two diagonal intratetramer interactions compete with the main interaction and weak intertetramer interactions connect the tetramers. The mainmore » intratetramer interaction is found to split into two inequivalent ones due to a structural distortion below 160 K. Cu 2PO 4OH is considered to be a good material to study the S=1/2 Heisenberg tetramer system.« less

  17. High performance sodium-ion hybrid capacitor based on Na2Ti2O4(OH)2 nanostructures

    NASA Astrophysics Data System (ADS)

    Babu, Binson; Shaijumon, M. M.

    2017-06-01

    Hybrid Na-ion capacitors bridge the performance gap between Na-ion batteries and supercapacitors and offer excellent energy and power characteristics. However, designing efficient anode and cathode materials with improved kinetics and long cycle life is essential for practical implementation of this technology. Herein, layered sodium titanium oxide hydroxide, Na2Ti2O4(OH)2, synthesized through hydrothermal technique, is studied as efficient anode material for hybrid Na-ion capacitor. Half-cell electrochemical studies vs. Na/Na+ showed excellent performance for Na2Ti2O4(OH)2 electrode, with ∼57.2% of the total capacity (323.3 C g-1 at 1.0 mV s-1) dominated by capacitive behavior and the remaining due to Na-intercalation. The obtained values are in good agreement with Trasatti plots indicating the potential of this material as efficient anode for hybrid Na-ion capacitor. Further, a full cell Na-ion capacitor is fabricated with Na2Ti2O4(OH)2 as anode and chemically activated Rice Husk Derived Porous Carbon (RHDPC-KOH) as cathode by using organic electrolyte. The hybrid device, operated at a maximum cell voltage of 4 V, exhibits stable electrochemical performance with a maximum energy density of ∼65 Wh kg-1 (at 500 W kg-1, 0.20 A g-1) and with more than ∼ 93% capacitive retention after 3000 cycles.

  18. Molecular pharmacodynamics of emixustat in protection against retinal degeneration.

    PubMed

    Zhang, Jianye; Kiser, Philip D; Badiee, Mohsen; Palczewska, Grazyna; Dong, Zhiqian; Golczak, Marcin; Tochtrop, Gregory P; Palczewski, Krzysztof

    2015-07-01

    Emixustat is a visual cycle modulator that has entered clinical trials as a treatment for age-related macular degeneration (AMD). This molecule has been proposed to inhibit the visual cycle isomerase RPE65, thereby slowing regeneration of 11-cis-retinal and reducing production of retinaldehyde condensation byproducts that may be involved in AMD pathology. Previously, we reported that all-trans-retinal (atRAL) is directly cytotoxic and that certain primary amine compounds that transiently sequester atRAL via Schiff base formation ameliorate retinal degeneration. Here, we have shown that emixustat stereoselectively inhibits RPE65 by direct active site binding. However, we detected the presence of emixustat-atRAL Schiff base conjugates, indicating that emixustat also acts as a retinal scavenger, which may contribute to its therapeutic effects. Using agents that lack either RPE65 inhibitory activity or the capacity to sequester atRAL, we assessed the relative importance of these 2 modes of action in protection against retinal phototoxicity in mice. The atRAL sequestrant QEA-B-001-NH2 conferred protection against phototoxicity without inhibiting RPE65, whereas an emixustat derivative incapable of atRAL sequestration was minimally protective, despite direct inhibition of RPE65. These data indicate that atRAL sequestration is an essential mechanism underlying the protective effects of emixustat and related compounds against retinal phototoxicity. Moreover, atRAL sequestration should be considered in the design of next-generation visual cycle modulators.

  19. Molecular pharmacodynamics of emixustat in protection against retinal degeneration

    PubMed Central

    Zhang, Jianye; Kiser, Philip D.; Badiee, Mohsen; Palczewska, Grazyna; Dong, Zhiqian; Golczak, Marcin; Tochtrop, Gregory P.; Palczewski, Krzysztof

    2015-01-01

    Emixustat is a visual cycle modulator that has entered clinical trials as a treatment for age-related macular degeneration (AMD). This molecule has been proposed to inhibit the visual cycle isomerase RPE65, thereby slowing regeneration of 11-cis-retinal and reducing production of retinaldehyde condensation byproducts that may be involved in AMD pathology. Previously, we reported that all-trans-retinal (atRAL) is directly cytotoxic and that certain primary amine compounds that transiently sequester atRAL via Schiff base formation ameliorate retinal degeneration. Here, we have shown that emixustat stereoselectively inhibits RPE65 by direct active site binding. However, we detected the presence of emixustat-atRAL Schiff base conjugates, indicating that emixustat also acts as a retinal scavenger, which may contribute to its therapeutic effects. Using agents that lack either RPE65 inhibitory activity or the capacity to sequester atRAL, we assessed the relative importance of these 2 modes of action in protection against retinal phototoxicity in mice. The atRAL sequestrant QEA-B-001-NH2 conferred protection against phototoxicity without inhibiting RPE65, whereas an emixustat derivative incapable of atRAL sequestration was minimally protective, despite direct inhibition of RPE65. These data indicate that atRAL sequestration is an essential mechanism underlying the protective effects of emixustat and related compounds against retinal phototoxicity. Moreover, atRAL sequestration should be considered in the design of next-generation visual cycle modulators. PMID:26075817

  20. Retinal Vasculitis

    PubMed Central

    Rosenbaum, James T.; Sibley, Cailin H.; Lin, Phoebe

    2016-01-01

    Purpose of review Ophthalmologists and rheumatologists frequently miscommunicate in consulting on patients with retinal vasculitis. This report seeks to establish a common understanding of the term, retinal vasculitis, and to review recent papers on this diagnosis. Recent findings 1) The genetic basis of some rare forms of retinal vascular disease have recently been described. Identified genes include CAPN5, TREX1, and TNFAIP3; 2) Behçet’s disease is a systemic illness that is very commonly associated with occlusive retinal vasculitis; 3) retinal imaging including fluorescein angiography and other newer imaging modalities has proven crucial to the identification and characterization of retinal vasculitis and its complications; 4) although monoclonal antibodies to IL-17A or IL-1 beta failed in trials for Behçet’s disease, antibodies to TNF alpha, either infliximab or adalimumab, have demonstrated consistent benefit in managing this disease. Interferon treatment and B cell depletion therapy via rituximab may be beneficial in certain types of retinal vasculitis. Summary Retinal vasculitis is an important entity for rheumatologists to understand. Retinal vasculitis associated with Behçet’s disease responds to monoclonal antibodies that neutralize TNF, but the many other forms of non-infectious retinal vasculitis may require alternate therapeutic management. PMID:26945335

  1. The Visual Cycle in the Inner Retina of Chicken and the Involvement of Retinal G-Protein-Coupled Receptor (RGR).

    PubMed

    Díaz, Nicolás M; Morera, Luis P; Tempesti, Tomas; Guido, Mario E

    2017-05-01

    The vertebrate retina contains typical photoreceptor (PR) cones and rods responsible for day/night vision, respectively, and intrinsically photosensitive retinal ganglion cells (ipRGCs) involved in the regulation of non-image-forming tasks. Rhodopsin/cone opsin photopigments in visual PRs or melanopsin (Opn4) in ipRGCs utilizes retinaldehyde as a chromophore. The retinoid regeneration process denominated as "visual cycle" involves the retinal pigment epithelium (RPE) or Müller glial cells. Opn4, on the contrary, has been characterized as a bi/tristable photopigment, in which a photon of one wavelength isomerizes 11-cis to all-trans retinal (Ral), with a second photon re-isomerizing it back. However, it is unknown how the chromophore is further metabolized in the inner retina. Nor is it yet clear whether an alternative secondary cycle occurs involving players such as the retinal G-protein-coupled receptor (RGR), a putative photoisomerase of unidentified inner retinal activity. Here, we investigated the role of RGR in retinoid photoisomerization in Opn4x (Xenopus ortholog) (+) RGC primary cultures free of RPE and other cells from chicken embryonic retinas. Opn4x (+) RGCs display significant photic responses by calcium fluorescent imaging and photoisomerize exogenous all-trans to 11-cis Ral and other retinoids. RGR was found to be expressed in developing retina and in primary cultures; when its expression was knocked down, the levels of 11-cis, all-trans Ral, and all-trans retinol in cultures exposed to light were significantly higher and those in all-trans retinyl esters lower than in dark controls. The results support a novel role for RGR in ipRGCs to modulate retinaldehyde levels in light, keeping the balance of inner retinal retinoid pools.

  2. The spectral properties and photosensitivities of analogue photopigments regenerated with 10- and 14-substituted retinal analogues.

    PubMed

    Crescitelli, F; Liu, R S

    1988-02-23

    Analogues of 11-cis- and 9-cis-retinal with substitutions at positions 10 and 14 were used to regenerate analogue photopigments with two opsins: that of the transmuted (cone-like) 521-pigment of Gekko gekko and that of the rhodopsin of Porichthys notatus. The spectral absorbances and photosensitivities of the regenerated photopigments were determined and compared, first, between the two systems of analogue photopigments, and second, in the responses to the two opsins. Unlike the 10-fluoropigments, the comparable 14-compounds were significantly red-shifted by 19-30 nm and their sensitivity to light was similar to that of the parent 11-cis- and 9-cis-pigments. These were the results for both analogue pigments. In contrast, the 10-pigments were spectrally located close to the wavelengths of the parent compounds and the photosensitivity was significantly reduced, especially in the case of the 9-cis-analogues. Evidence was obtained for a steric hindrance effect at position 14, for no regeneration was obtained when methyl or ethyl groups were at this carbon. In the 10-substituted retinals, steric hindrance was noted only for the gecko; only the fluorosubstituted, but not the chloro-, the methyl- or the ethyl-substituted, retinals reacted. With the fish opsin, pigments were regenerated with all but the ethyl-substituted retinal. The gecko opsin appears to have a more restricted binding site. Another feature of the gecko was related to the chloride bathochromic and hyperchromic effects, in which the 521-pigment prepared in a chloride-deficient state has a blue-shifted spectrum compared with the spectrum obtained after the addition of chloride, and its extinction is raised by the addition of chloride to give a mean ratio of 1.23 for the two extinctions, one with, the other without, added chloride. The 11-cis-10-F-analogue pigment gave both chloride effects and the hyperchromic ratio was the same as that recorded for the native visual pigment. In contrast, the pigment formed

  3. Primary amines protect against retinal degeneration in mouse models of retinopathies.

    PubMed

    Maeda, Akiko; Golczak, Marcin; Chen, Yu; Okano, Kiichiro; Kohno, Hideo; Shiose, Satomi; Ishikawa, Kaede; Harte, William; Palczewska, Grazyna; Maeda, Tadao; Palczewski, Krzysztof

    2011-12-25

    Vertebrate vision is initiated by photoisomerization of the visual pigment chromophore 11-cis-retinal and is maintained by continuous regeneration of this retinoid through a series of reactions termed the retinoid cycle. However, toxic side reaction products, especially those involving reactive aldehyde groups of the photoisomerized product, all-trans-retinal, can cause severe retinal pathology. Here we lowered peak concentrations of free all-trans-retinal with primary amine-containing Food and Drug Administration (FDA)-approved drugs that did not inhibit chromophore regeneration in mouse models of retinal degeneration. Schiff base adducts between all-trans-retinal and these amines were identified by MS. Adducts were observed in mouse eyes only when an experimental drug protected the retina from degeneration in both short-term and long-term treatment experiments. This study demonstrates a molecular basis of all-trans-retinal-induced retinal pathology and identifies an assemblage of FDA-approved compounds with protective effects against this pathology in a mouse model that shows features of Stargardt's disease and age-related retinal degeneration.

  4. Primary amines protect against retinal degeneration in mouse models of retinopathies

    PubMed Central

    Maeda, Akiko; Golczak, Marcin; Chen, Yu; Okano, Kiichiro; Kohno, Hideo; Shiose, Satomi; Ishikawa, Kaede; Harte, William; Palczewska, Grazyna; Maeda, Tadao; Palczewski, Krzysztof

    2011-01-01

    Vertebrate vision is initiated by photoisomerization of the visual pigment chromophore, 11-cis-retinal, and is maintained by continuous regeneration of this retinoid through a series of reactions termed the retinoid cycle. However, toxic side reaction products, especially those involving reactive aldehyde groups of the photoisomered product, all-trans-retinal, can cause severe retinal pathology. Here we lowered peak concentrations of free all-trans-retinal with primary amine-containing FDA-approved drugs that did not inhibit chromophore regeneration in mouse models of retinal degeneration. Schiff base adducts between all-trans-retinal and these amines were identified by mass spectrometry. Adducts were observed in mouse eyes only when an experimental drug protected the retina from degeneration in both short-term and long-term treatment experiments. This study demonstrates a molecular basis of all-trans-retinal-induced retinal pathology and identifies an assemblage of FDA-approved compounds with protective effects against this pathology in a mouse model that displays features of Stargardt’s and age-related retinal degeneration. PMID:22198730

  5. Retinal vasculitis.

    PubMed

    Abu El-Asrar, Ahmed M; Herbort, Carl P; Tabbara, Khalid F

    2005-12-01

    Retinal vasculitis is a sight-threatening intraocular inflammation affecting the retinal vessels. It may occur as an isolated ocular condition, as a manifestation of infectious or neoplastic disorders, or in association with a systemic inflammatory disease. The search for an underlying etiology should be approached in a multidisciplinary fashion based on a thorough history, review of systems, physical examination, and laboratory evaluation. Discrimination between infectious and noninfectious etiologies of retinal vasculitis is important because their treatment is different. This review is based on recently published articles on retinal vasculitis and deals with its clinical diagnosis, its link with systemic diseases, and its laboratory investigation.

  6. Retinal detachment.

    PubMed

    Fraser, Scott; Steel, David

    2010-11-24

    Rhegmatogenous retinal detachment (RRD) is the most common form of retinal detachment, where a retinal "break" allows the ingress of fluid from the vitreous cavity to the subretinal space, resulting in retinal separation. It occurs in about 1 in 10,000 people a year. We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of interventions to prevent progression from retinal breaks or lattice degeneration to retinal detachment? What are the effects of different surgical interventions in people with rhegmatogenous retinal detachment? What are the effects of interventions to treat proliferative vitreoretinopathy occurring as a complication of retinal detachment or previous treatment for retinal detachment? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2010 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). We found 21 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. In this systematic review, we present information relating to the effectiveness and safety of the following interventions: corticosteroids, cryotherapy, daunorubicin, fluorouracil plus low molecular weight heparin, laser photocoagulation, pneumatic retinopexy, scleral buckling, short-acting or long-acting gas tamponade, silicone oil tamponade, and vitrectomy.

  7. Retinal detachment.

    PubMed

    Steel, David; Fraser, Scott

    2008-02-15

    Rhegmatogenous retinal detachment (RRD) is the most common form of retinal detachment, where a retinal "break" allows the ingress of fluid from the vitreous cavity to the subretinal space, resulting in retinal separation. It occurs in about 1 in 10,000 people a year. We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of interventions to prevent progression from retinal breaks or lattice degeneration to retinal detachment? What are the effects of different surgical interventions in people with rhegmatogenous retinal detachment? What are the effects of interventions to treat proliferative vitreoretinopathy occurring as a complication of retinal detachment or previous treatment for retinal detachment? We searched: Medline, Embase, The Cochrane Library and other important databases up to September 2006 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). We found 8 systematic reviews, RCTs or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. In this systematic review we present information relating to the effectiveness and safety of the following interventions: cryotherapy, fluorouracil plus low-molecular weight heparin added to infusion solution during vitrectomy surgery for proliferative vitreoretinopathy, laser photocoagulation, pneumatic retinopexy, scleral buckling, short-acting or long-acting gas tamponade, and silicone oil vitrectomy.

  8. Retinal detachment

    PubMed Central

    2010-01-01

    Introduction Rhegmatogenous retinal detachment (RRD) is the most common form of retinal detachment, where a retinal "break" allows the ingress of fluid from the vitreous cavity to the subretinal space, resulting in retinal separation. It occurs in about 1 in 10,000 people a year. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of interventions to prevent progression from retinal breaks or lattice degeneration to retinal detachment? What are the effects of different surgical interventions in people with rhegmatogenous retinal detachment? What are the effects of interventions to treat proliferative vitreoretinopathy occurring as a complication of retinal detachment or previous treatment for retinal detachment? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2010 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 21 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review, we present information relating to the effectiveness and safety of the following interventions: corticosteroids, cryotherapy, daunorubicin, fluorouracil plus low molecular weight heparin, laser photocoagulation, pneumatic retinopexy, scleral buckling, short-acting or long-acting gas tamponade, silicone oil tamponade, and vitrectomy. PMID:21406128

  9. Retinal detachment

    PubMed Central

    2009-01-01

    Introduction Rhegmatogenous retinal detachment (RRD) is the most common form of retinal detachment, where a retinal "break" allows the ingress of fluid from the vitreous cavity to the subretinal space, resulting in retinal separation. It occurs in about 1 in 10,000 people a year. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of interventions to prevent progression from retinal breaks or lattice degeneration to retinal detachment? What are the effects of different surgical interventions in people with rhegmatogenous retinal detachment? What are the effects of interventions to treat proliferative vitreoretinopathy occurring as a complication of retinal detachment or previous treatment for retinal detachment? We searched: Medline, Embase, The Cochrane Library, and other important databases up to March 2009 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 20 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review, we present information relating to the effectiveness and safety of the following interventions: corticosteroids; cryotherapy; daunorubicin; fluorouracil plus low-molecular-weight heparin; laser photocoagulation; pneumatic retinopexy; scleral buckling; short-acting or long-acting gas tamponade; silicone oil tamponade; and vitrectomy. PMID:19450333

  10. Vibrational spectroscopy of the phosphate mineral kovdorskite - Mg2PO4(OH)ṡ3H2O

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; López, Andrés; Xi, Yunfei; Granja, Amanda; Scholz, Ricardo; Lima, Rosa Malena Fernandes

    2013-10-01

    The mineral kovdorskite Mg2PO4(OH)ṡ3H2O was studied by electron microscopy, thermal analysis and vibrational spectroscopy. A comparison of the vibrational spectroscopy of kovdorskite is made with other magnesium bearing phosphate minerals and compounds. Electron probe analysis proves the mineral is very pure. The Raman spectrum is characterized by a band at 965 cm-1 attributed to the PO43- ν1 symmetric stretching mode. Raman bands at 1057 and 1089 cm-1 are attributed to the PO43- ν3 antisymmetric stretching modes. Raman bands at 412, 454 and 485 cm-1 are assigned to the PO43- ν2 bending modes. Raman bands at 536, 546 and 574 cm-1 are assigned to the PO43- ν4 bending modes. The Raman spectrum in the OH stretching region is dominated by a very sharp intense band at 3681 cm-1 assigned to the stretching vibration of OH units. Infrared bands observed at 2762, 2977, 3204, 3275 and 3394 cm-1 are attributed to water stretching bands. Vibrational spectroscopy shows that no carbonate bands are observed in the spectra; thus confirming the formula of the mineral as Mg2PO4(OH)ṡ3H2O.

  11. Retinal meteor.

    PubMed

    Venkatesh, Ramesh; Gurav, Prachi; Dave, Prachi Abhishek; Roy, Sankhadeep

    2017-09-01

    We describe a case of a 65-year old man diagnosed with retinal vasoproliferative tumour secondary to posterior uveitis. The fluorescein angiography shows an interesting meteor-like leak emanating from the tumour and rising towards the superior retina in the later frames of the angiogram. Pictorially, we call it the "Retinal Meteor" and also describe the possible mechanism for this pattern of leakage.

  12. Retinal remodeling.

    PubMed

    Jones, B W; Kondo, M; Terasaki, H; Lin, Y; McCall, M; Marc, R E

    2012-07-01

    Retinal photoreceptor degeneration takes many forms. Mutations in rhodopsin genes or disorders of the retinal pigment epithelium, defects in the adenosine triphosphate binding cassette transporter, ABCR gene defects, receptor tyrosine kinase defects, ciliopathies and transport defects, defects in both transducin and arrestin, defects in rod cyclic guanosine 3',5'-monophosphate phosphodiesterase, peripherin defects, defects in metabotropic glutamate receptors, synthetic enzymatic defects, defects in genes associated with signaling, and many more can all result in retinal degenerative disease like retinitis pigmentosa (RP) or RP-like disorders. Age-related macular degeneration (AMD) and AMD-like disorders are possibly due to a constellation of potential gene targets and gene/gene interactions, while other defects result in diabetic retinopathy or glaucoma. However, all of these insults as well as traumatic insults to the retina result in retinal remodeling. Retinal remodeling is a universal finding subsequent to retinal degenerative disease that results in deafferentation of the neural retina from photoreceptor input as downstream neuronal elements respond to loss of input with negative plasticity. This negative plasticity is not passive in the face of photoreceptor degeneration, with a phased revision of retinal structure and function found at the molecular, synaptic, cell, and tissue levels involving all cell classes in the retina, including neurons and glia. Retinal remodeling has direct implications for the rescue of vision loss through bionic or biological approaches, as circuit revision in the retina corrupts any potential surrogate photoreceptor input to a remnant neural retina. However, there are a number of potential opportunities for intervention that are revealed through the study of retinal remodeling, including therapies that are designed to slow down photoreceptor loss, interventions that are designed to limit or arrest remodeling events, and

  13. Co5In(BTC)4[B2O4(OH)]2: the first MOF material constructed by borate polyanions and carboxylate mixed ligands.

    PubMed

    Li, Sa-Ying; Liu, Zhi-Hong

    2016-01-07

    A novel heterometallic organic-inorganic hybrid MOF material, Co5In(BTC)4[B2O4(OH)]2, has been synthesized under ionothermal conditions. Its structure is characterized as a 3D open framework constructed by the Co2.5In0.5[B2O4(OH)] cluster and the 1,3,5-benzenetricarboxylate ligand. Furthermore, its fluorescent and adsorption properties have also been studied.

  14. Retinal detachment

    PubMed Central

    2014-01-01

    Introduction Rhegmatogenous retinal detachment (RRD) is the most common form of retinal detachment, where a retinal 'break' allows the ingress of fluid from the vitreous cavity to the subretinal space, resulting in retinal separation. It occurs in about 1 in 10,000 people a year. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of different surgical interventions in people with rhegmatogenous retinal detachment? What are the effects of interventions to treat proliferative vitreoretinopathy occurring as a complication of retinal detachment or previous treatment for retinal detachment? We searched: Medline, Embase, The Cochrane Library, and other important databases up to September 2013 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 14 studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review, we present information relating to the effectiveness and safety of the following interventions: corticosteroids, daunorubicin, fluorouracil plus low molecular weight heparin, pneumatic retinopexy, scleral buckling, short-acting or long-acting gas tamponade, silicone oil tamponade, and vitrectomy. PMID:24807890

  15. Retinal Prosthesis

    PubMed Central

    Weiland, James D.; Humayun, Mark S.

    2015-01-01

    Retinal prosthesis have been translated from the laboratory to the clinical over the past two decades. Currently, two devices have regulatory approval for the treatment of retinitis pigmentosa. These devices provide partial sight restoration and patients use this improved vision in their everyday lives. Improved mobility and object detection are some of the more notable findings from the clinical trials. However, significant vision restoration will require both better technology and improved understanding of the interaction between electrical stimulation and the retina. This paper reviews the recent clinical trials, highlights technology breakthroughs that will contribute to next generation of retinal prostheses. PMID:24710817

  16. XPS and UPS Investigation of NH4OH-Exposed Cu(In,Ga)Se2 Thin Films

    SciTech Connect

    Perkins, C. L.; Hasoon, F. S.; Al-Thani, H. A.

    2005-02-01

    Photoelectron spectroscopy was used to determine the compositional and electronic changes occurring in Cu(In,Ga)Se2 thin films as a result of immersion in aqueous ammonia solution. We find that NH4OH-treated CIGS surfaces are preferentially etched of indium and gallium, resulting in the formation of a thin layer of a degenerate Cu-Se compound that we tentatively identify as Cu2Se. The work function of ammonia-treated samples is found to increase by 0.6 eV relative to as-grown CIGS thin films. The uniformity of chemical bath effects (etching & deposition) was found to be improved by the addition to the bath of a non-ionic surfactant.more » Initial device results show that the new surfactant-based chemical bath deposition (CBD) method may lead to better and thinner CdS buffer layers.« less

  17. Magnetization and ESR studies on C u4(OH) 6FCl : An antiferromagnet with a kagome lattice

    NASA Astrophysics Data System (ADS)

    Yue, X. Y.; Ouyang, Z. W.; Wang, J. F.; Wang, Z. X.; Xia, Z. C.; He, Z. Z.

    2018-02-01

    We have synthesized a spin-1/2 antiferromagnet, C u4(OH) 6FCl , containing kagome lattices. The magnetic susceptibility gives a Curie-Weiss temperature θCW=-135 K , nearest-neighbor exchange J =-166 K , and two magnetic anomalies at T1=15 K and T2=4.8 K with weak ferromagnetism. However, the specific heat curve does not exhibit λ-like peaks expected for long-range magnetic order. The high-field ESR data are strongly correlated with the magnetism. There are a gapless mode ω1 observed at all temperatures and two gapped modes, ω2 and ω3, corresponding to different temperature regions: T

  18. Stereoselective Metabolism of Bupropion to OH-bupropion, Threohydrobupropion, Erythrohydrobupropion, and 4'-OH-bupropion in vitro.

    PubMed

    Sager, Jennifer E; Price, Lauren S L; Isoherranen, Nina

    2016-10-01

    Bupropion is a widely used antidepressant, smoking cessation aid, and weight-loss therapy. It is administered as a racemic mixture, but the pharmacokinetics and activity of bupropion are stereoselective. The activity and side effects of bupropion are attributed to bupropion and its metabolites S,S- and R,R-OH-bupropion, threohydrobupropion, and erythrohydrobupropion. Yet the stereoselective metabolism in vitro and the enzymes contributing to the stereoselective disposition of bupropion have not been characterized. In humans, the fraction of bupropion metabolized (fm) to the CYP2B6 probe metabolite OH-bupropion is 5-16%, but ticlopidine increases bupropion exposure by 61%, suggesting a 40% CYP2B6 and/or CYP2C19 fm for bupropion. Yet, the CYP2C19 contribution to bupropion clearance has not been defined, and the enzymes contributing to overall bupropion metabolite formation have not been fully characterized. The aim of this study was to characterize the stereoselective metabolism of bupropion in vitro to explain the stereoselective pharmacokinetics and the effect of drug-drug interactions (DDIs) and CYP2C19 pharmacogenetics on bupropion exposure. The data predict that threohydrobupropion accounts for 50 and 82%, OH-bupropion for 34 and 12%, erythrohydrobupropion for 8 and 4%, and 4'-OH-bupropion for 8 and 2% of overall R- and S-bupropion clearance, respectively. The fm,CYP2B6 was predicted to be 21%, and the fm,CYP2C19, 6% for racemic bupropion. Importantly, ticlopidine was found to inhibit all metabolic pathways of bupropion in vitro, including threohydrobupropion, erythrohydrobupropion, and 4'OH-bupropion formation, explaining the in vivo DDI. The stereoselective pharmacokinetics of bupropion were quantitatively explained by the in vitro metabolic clearances and in vivo interconversion between bupropion stereoisomers. Copyright © 2016 by The Author(s).

  19. Chaetomium retinitis.

    PubMed

    Tabbara, Khalid F; Wedin, Keith; Al Haddab, Saad

    2010-01-01

    To report a case of Chaetomium atrobrunneum retinitis in a patient with Hodgkin lymphoma. We studied the ocular manifestations of an 11-year-old boy with retinitis. Biomicroscopy, ophthalmoscopy, and fundus photography were done. Magnetic resonance imaging of the brain was performed. A vitreous biopsy was subjected to viral, bacterial, and fungal cultures. Vitreous culture grew C. atrobrunneum. Magnetic resonance imaging showed multiple cerebral lesions consistent with an infectious process. The patient was given intravenous voriconazole and showed improvement of the ocular and central nervous system lesions. We report a case of central nervous system and ocular lesions by C. atrobrunneum. The retinitis was initially misdiagnosed as cytomegaloviral retinitis. Vitreous biopsy helped in the early diagnosis and prompt treatment of a life- and vision-threatening infection.

  20. Retinal Disorders

    MedlinePlus

    ... be serious enough to cause blindness. Examples are Macular degeneration - a disease that destroys your sharp, central vision Diabetic eye disease Retinal detachment - a medical emergency, when the retina is ... children. Macular pucker - scar tissue on the macula Macular hole - ...

  1. Retinal meteor

    PubMed Central

    Venkatesh, Ramesh; Gurav, Prachi; Dave, Prachi Abhishek; Roy, Sankhadeep

    2017-01-01

    We describe a case of a 65-year old man diagnosed with retinal vasoproliferative tumour secondary to posterior uveitis. The fluorescein angiography shows an interesting meteor-like leak emanating from the tumour and rising towards the superior retina in the later frames of the angiogram. Pictorially, we call it the “Retinal Meteor” and also describe the possible mechanism for this pattern of leakage. PMID:28905838

  2. Thermal Stability of Rhodopsin and Progression of Retinitis Pigmentosa

    PubMed Central

    Liu, Monica Yun; Liu, Jian; Mehrotra, Devi; Liu, Yuting; Guo, Ying; Baldera-Aguayo, Pedro A.; Mooney, Victoria L.; Nour, Adel M.; Yan, Elsa C. Y.

    2013-01-01

    Over 100 point mutations in the rhodopsin gene have been associated with retinitis pigmentosa (RP), a family of inherited visual disorders. Among these, we focused on characterizing the S186W mutation. We compared the thermal properties of the S186W mutant with another RP-causing mutant, D190N, and with WT rhodopsin. To assess thermal stability, we measured the rate of two thermal reactions contributing to the thermal decay of rhodopsin as follows: thermal isomerization of 11-cis-retinal and hydrolysis of the protonated Schiff base linkage between the 11-cis-retinal chromophore and opsin protein. We used UV-visible spectroscopy and HPLC to examine the kinetics of these reactions at 37 and 55 °C for WT and mutant rhodopsin purified from HEK293 cells. Compared with WT rhodopsin and the D190N mutant, the S186W mutation dramatically increases the rates of both thermal isomerization and dark state hydrolysis of the Schiff base by 1–2 orders of magnitude. The results suggest that the S186W mutant thermally destabilizes rhodopsin by disrupting a hydrogen bond network at the receptor's active site. The decrease in the thermal stability of dark state rhodopsin is likely to be associated with higher levels of dark noise that undermine the sensitivity of rhodopsin, potentially accounting for night blindness in the early stages of RP. Further studies of the thermal stability of additional pathogenic rhodopsin mutations in conjunction with clinical studies are expected to provide insight into the molecular mechanism of RP and test the correlation between rhodopsin's thermal stability and RP progression in patients. PMID:23625926

  3. Pharmacotherapy of retinal disease with visual cycle modulators.

    PubMed

    Hussain, Rehan M; Gregori, Ninel Z; Ciulla, Thomas A; Lam, Byron L

    2018-04-01

    Pharmacotherapy with visual cycle modulators (VCMs) is under investigation for retinitis pigmentosa (RP), Leber congenital amaurosis (LCA), Stargardt macular dystrophy (SMD) and nonexudative age-related macular degeneration (AMD), all blinding diseases that lack effective treatment options. Areas covered: The authors review investigational VCMs, including oral retinoids, 9-cis-retinyl-acetate (zuretinol) and 9-cis-β-carotene, which restore 11-cis-retinal levels in RP and LCA caused by LRAT and RPE65 gene mutations, and may improve visual acuity and visual fields. Therapies for SMD aiming to decrease accumulation of toxic Vitamin A dimers and lipofuscin in the retina and retinal pigment epithelium (RPE) include C20-D3-vitamin A (ALK-001), isotretinoin, VM200, emixustat, and A1120. Mouse models of SMD show promising data for these treatments, though proof of efficacy in humans is currently lacking. Fenretinide and emixustat are investigational VCMs for dry AMD, though neither has been shown to reduce geographic atrophy or improve vision in human trials. A1120 prevents retinol transport into the RPE and may spare the side effects typically seen in VCMs (nyctalopia and chromatopsia) per mouse studies. Expert opinion: Oral VCMs may be feasible treatment options for degenerative retinal diseases based on pre-clinical and some early clinical studies. Further trials are warranted to assess their efficacy and safety in humans.

  4. Influence of surface modification with Sn 6O 4(OH) 4 on electrochemical performance of ZnO in Zn/Ni secondary cells

    NASA Astrophysics Data System (ADS)

    Yuan, Y. F.; Tu, J. P.; Wu, H. M.; Zhang, C. Q.; Wang, S. F.; Zhao, X. B.

    The surface-modified ZnO by Sn 6O 4(OH) 4 was prepared by a simple hydrolyzation process and the influence of Sn 6O 4(OH) 4 on electrochemical performance of ZnO was investigated by charge/discharge cycling test, slow rate cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Compared with the unmodified ZnO, the Sn 6O 4(OH) 4-modified ZnO showed improved electrochemical properties, such as superior electrochemical cycle stability, higher discharge capacity and utilization ratio. The surface modification could suppress the dissolution of ZnO in the alkaline electrolyte and maintain the electrochemical activity of ZnO. When the Sn 6O 4(OH) 4 content reached 27 wt.%, the discharge capacity of the modified ZnO hardly declined over 80 cycling test, the average utilization ratio could reach 98.5%, and the modified ZnO electrodes had no obvious weight loss after the cycling tests. However, the charge/discharge plateau voltage with the Sn 6O 4(OH) 4-modified ZnO slightly decreased. For the modified ZnO electrodes, two anodic peaks occurred in the CV curves, and the charge transfer resistance increased from the EIS results, both of which were ascribed to the suppressive effect of surface modification on the electrochemical reactions.

  5. Elasticity of Hydrous Aluminosilicate Mineral, Topaz-OH (Al2SiO4(OH)2) at High Pressures

    NASA Astrophysics Data System (ADS)

    Hariharan, A.; Mookherjee, M.; Tsuchiya, J.

    2015-12-01

    We examined the equation of state and high-pressure elasticity of the hydrous aluminosilicate mineral topaz-OH (Al2SiO4(OH)2) using first principles simulation. Topaz-OH is a hydrous phase in the Al2O3-SiO2-H2O (ASH) ternary system, which is relevant for the mineral phase relations in the hydrated sedimentary layer of subducting slabs. Based on recent experiments, it is known that the protons in the topaz-OH exhibit positional disorder with half occupancy over two distinct crystallographic sites. In order to adequately depict the proton environment in the topaz-OH, we examined five crystal structure models with distinct configuration for the protons. Upon full geometry optimization, we find that there are two distinct crystal structures for the topaz-OH. The first crystal structure has an orthorhombic Pbnm space group symmetry, and the second crystal structure has a monoclinic P21/c space group symmetry. At static conditions, the monoclinic (P21/c) topaz-OH has lower energy compared to the orthorhombic (Pbnm) topaz-OH. The energy of the monoclinic (P21/c) topaz-OH remains stable at least up to 40 GPa, i.e., pressures beyond the thermodynamic stability of the topaz-OH. Based on the results from first principles simulation, the equation of state for the monoclinic topaz-OH is well represented by a third-order Birch-Murnaghan formulation, with V0 = 348.63 (±0.04) Å3, K0 = 164.7 (±0.04) GPa, and K'0 = 4.24 (±0.05). The equation of state for the orthorhombic topaz-OH is well represented by a third-order Birch-Murnaghan formulation, with V0 = 352.47 (±0.04) Å3, K0 = 166.4 (±0.06) GPa, and K'0 = 4.03 (±0.04). While the bulk modulus is very similar for both the monoclinic and orthorhombic topaz-OH, the shear elastic moduli are very sensitive to the position of the proton and the orientation of the hydroxyl (O-H) groups. In the hydrated sedimentary layer of a subducting slab, transformation of a mineral assemblage consisting of coesite (SiO2) and diaspore (AlOOH) to

  6. Phase change of hydromagnesite, Mg5(CO3)4(OH)2 4H2O by thermal decomposition

    NASA Astrophysics Data System (ADS)

    Yamamoto, G. I.; Kyono, A.; Tamura, T.

    2017-12-01

    In recent years, the global warming is the most important environment problem, and thus attempts of CO2 geological storage have been made to remove carbon dioxide from the atmosphere all over the world (XUE and Nakao 2008). Regarding mineral CO2 sequestration, CO2 is chemically stored in solid carbonates by carbonation of minerals. Magnesium and calcium carbonates have long been known as a good CO2 storage. Hydrous magnesium carbonates can be, however, considered as much better candidates for CO2 storage because they precipitate easily from aqueous solutions. The typical hydrous magnesium carbonates are nesquehonite, MgCO3 3H2O and hydromagnesite, Mg5(CO3)4(OH)2 4H2O. Concerning their thermal properties, the former has been studied in detail, whereas, the latter is not enough. In this study, we performed in-site high-temperature X-ray diffraction (XRD) and thermogravimetric and differential thermal (TG-DTA) analyses to reveal the phase change of hydromagnesite at high temperature. The high-temperature XRD and TG-DTA were measured up to 320 oC and 550 oC, respectively. The results of in-site high-temperature XRD showed that, no significant change was observed up to 170 oC. With increasing temperature, the intensities of started to decrease at 200 oC, and all peaks disappeared at 290 oC. Above the temperature of the decomposition a few peaks corresponding to periclase appeared. The results of TG-DTA clearly showed that there were two weight loss steps in the temperature range of 200 to 340 oC and 340 to 500 oC, which correspond to the dehydration and decarbonation of hydromagnesite, respectively. These weight losses were accompanied by the endothermic maxima in the DTA. The dihydroxylation of hydromagnesite is spread over the two steps. Therefore, hydromagnesite decomposes into periclase, carbon dioxide, and water without passing through magnesite around 300 oC as following reaction: Mg5(CO3)4(OH)2 4H2O → 5MgO + 4CO2 + 5H2O.

  7. High-quality draft genome sequence of Sedimenticola selenatireducens strain AK4OH1T, a gammaproteobacterium isolated from estuarine sediment

    SciTech Connect

    Louie, Tiffany S.; Giovannelli, Donato; Yee, Nathan

    2016-09-08

    Sedimenticola selenatireducens strain AK4OH1 T (= DSM 17993 T = ATCC BAA-1233 T) is a microaerophilic bacterium isolated from sediment from the Arthur Kill intertidal strait between New Jersey and Staten Island, NY. S. selenatireducens is Gram-negative and belongs to the Gammaproteobacteria. Strain AK4OH1 T was the first representative of its genus to be isolated for its unique coupling of the oxidation of aromatic acids to the respiration of selenate. It is a versatile heterotroph and can use a variety of carbon compounds, but can also grow lithoautotrophically under hypoxic and anaerobic conditions. Furthermore, the draft genome comprises 4,588,530 bpmore » and 4276 predicted protein-coding genes including genes for the anaerobic degradation of 4-hydroxybenzoate and benzoate. We report the main features of the genome of S. selenatireducens strain AK4OH1 T.« less

  8. Frustrated spin chain physics near the Majumdar-Ghosh point in szenicsite Cu3(MoO4)(OH)4

    NASA Astrophysics Data System (ADS)

    Lebernegg, Stefan; Janson, Oleg; Rousochatzakis, Ioannis; Nishimoto, Satoshi; Rosner, Helge; Tsirlin, Alexander A.

    2017-01-01

    In this joint experimental and theoretical work magnetic properties of the Cu2 + mineral szenicsite Cu3(MoO4) (OH) 4 are investigated. This compound features isolated triple chains in its crystal structure, where the central chain involves an edge-sharing geometry of the CuO4 plaquettes, while the two side chains feature a corner-sharing zigzag geometry. The magnetism of the side chains can be described in terms of antiferromagnetic dimers with a coupling larger than 200 K. The central chain was found to be a realization of the frustrated antiferromagnetic J1-J2 chain model with J1≃68 K and a sizable second-neighbor coupling J2. The central and side chains are nearly decoupled owing to interchain frustration. Therefore, the low-temperature behavior of szenicsite should be entirely determined by the physics of the central frustrated J1-J2 chain. Our heat-capacity measurements reveal an accumulation of magnetic entropy at low temperatures and suggest a proximity of the system to the Majumdar-Ghosh point of the antiferromagnetic J1-J2 spin chain, J2/J1=0.5 .

  9. Thermal analysis and vibrational spectroscopic characterization of the boro silicate mineral datolite - CaBSiO4(OH)

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Xi, Yunfei; Scholz, Ricardo; Lima, Rosa Malena Fernandes; Horta, Laura Frota Campos; Lopez, Andres

    2013-11-01

    The objective of this work is to determine the thermal stability and vibrational spectra of datolite CaBSiO4(OH) and relate these properties to the structure of the mineral. The thermal analysis of datolite shows a mass loss of 5.83% over a 700-775 °C temperature range. This mass loss corresponds to 1 water (H2O) molecules pfu. A quantitative chemical analysis using electron probe was undertaken. The Raman spectrum of datolite is characterized by bands at 917 and 1077 cm-1 assigned to the symmetric stretching modes of BO and SiO tetrahedra. A very intense Raman band is observed at 3498 cm-1 assigned to the stretching vibration of the OH units in the structure of datolite. BOH out-of-plane vibrations are characterized by the infrared band at 782 cm-1. The vibrational spectra are based upon the structure of datolite based on sheets of four- and eight-membered rings of alternating SiO4 and BO3(OH) tetrahedra with the sheets bonded together by calcium atoms.

  10. Thermal analysis and vibrational spectroscopic characterization of the boro silicate mineral datolite - CaBSiO4(OH).

    PubMed

    Frost, Ray L; Xi, Yunfei; Scholz, Ricardo; Lima, Rosa Malena Fernandes; Horta, Laura Frota Campos; Lopez, Andres

    2013-11-01

    The objective of this work is to determine the thermal stability and vibrational spectra of datolite CaBSiO4(OH) and relate these properties to the structure of the mineral. The thermal analysis of datolite shows a mass loss of 5.83% over a 700-775°C temperature range. This mass loss corresponds to 1 water (H2O) molecules pfu. A quantitative chemical analysis using electron probe was undertaken. The Raman spectrum of datolite is characterized by bands at 917 and 1077cm(-1) assigned to the symmetric stretching modes of BO and SiO tetrahedra. A very intense Raman band is observed at 3498cm(-1) assigned to the stretching vibration of the OH units in the structure of datolite. BOH out-of-plane vibrations are characterized by the infrared band at 782cm(-1). The vibrational spectra are based upon the structure of datolite based on sheets of four- and eight-membered rings of alternating SiO4 and BO3(OH) tetrahedra with the sheets bonded together by calcium atoms. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Retinal Conformation and Dynamics in Activation of Rhodopsin Illuminated by Solid-state 2H NMR Spectroscopy†

    PubMed Central

    Brown, Michael F.; Martínez-Mayorga, Karina; Nakanishi, Koji; Salgado, Gilmar F. J.; Struts, Andrey V.

    2010-01-01

    Solid-state NMR spectroscopy gives a powerful avenue for investigating G protein-coupled receptors and other integral membrane proteins in a native-like environment. This article reviews the use of solid-state 2H NMR to study the retinal cofactor of rhodopsin in the dark state as well as the meta I and meta II photointermediates. Site-specific 2H NMR labels have been introduced into three regions (methyl groups) of retinal that are crucially important for the photochemical function of rhodopsin. Despite its phenomenal stability 2H NMR spectroscopy indicates retinal undergoes rapid fluctuations within the protein binding cavity. The spectral lineshapes reveal the methyl groups spin rapidly about their three-fold (C3) axes with an order parameter for the off-axial motion of SC3 ≈ 0.9. For the dark state, the 2H NMR structure of 11-cis-retinal manifests torsional twisting of both the polyene chain and the β-ionone ring due to steric interactions of the ligand and the protein. Retinal is accommodated within the rhodopsin binding pocket with a negative pretwist about the C11=C12 double bond. Conformational distortion explains its rapid photochemistry and reveals the trajectory of the 11-cis to trans isomerization. In addition, 2H NMR has been applied to study the retinylidene dynamics in the dark and light-activated states. Upon isomerization there are drastic changes in the mobility of all three methyl groups. The relaxation data support an activation mechanism whereby the β-ionone ring of retinal stays in nearly the same environment, without a large displacement of the ligand. Interactions of the β-ionone ring and the retinylidene Schiff base with the protein transmit the force of the retinal isomerization. Solid-state 2H NMR thus provides information about the flow of energy that triggers changes in hydrogen-bonding networks and helix movements in the activation mechanism of the photoreceptor. PMID:19267870

  12. All-trans retinal levels and formation of lipofuscin precursors after bleaching in rod photoreceptors from wild type and Abca4-/- mice.

    PubMed

    Adler, Leopold; Chen, Chunhe; Koutalos, Yiannis

    2017-02-01

    The accumulation of lipofuscin in the cells of the retinal pigment epithelium (RPE) is thought to play an important role in the development and progression of degenerative diseases of the retina. The bulk of RPE lipofuscin originates in reactions of the rhodopsin chromophore, retinal, with components of the photoreceptor outer segment. The 11-cis retinal isomer is generated in the RPE and supplied to rod photoreceptor outer segments where it is incorporated as the chromophore of rhodopsin. It is photoisomerized during light detection to all-trans and subsequently released by photoactivated rhodopsin as all-trans retinal, which is removed through reduction to all-trans retinol in a reaction requiring metabolic input in the form of NADPH. Both 11-cis and all-trans retinal can form lipofuscin precursor fluorophores in rod photoreceptor outer segments. Increased accumulation of lipofuscin has been suggested to result from excess formation of lipofuscin precursors due to buildup of all-trans retinal released by light exposure. In connection with this suggestion, the Abca4 transporter protein, an outer segment protein defects in which result in recessive Stargardt disease, has been proposed to promote the removal of all-trans retinal by facilitating its availability for reduction. To examine this possibility, we have measured the outer segment levels of all-trans retinal, all-trans retinol, and of lipofuscin precursors after bleaching by imaging the fluorescence of single rod photoreceptors isolated from wild type and Abca4 -/- mice. We found that all-trans retinol and all-trans retinal levels increased after bleaching in both wild type and Abca4 -/- rods. At all times after bleaching, there was no significant difference in all-trans retinal levels between the two strains. All-trans retinol levels were not significantly different between the two strains at early times, but were lower in Abca4 -/- rods at times longer than 20 min after bleaching. Bleaching in the

  13. All-trans retinal levels and formation of lipofuscin precursors after bleaching in rod photoreceptors from wild type and Abca4−/− mice

    PubMed Central

    Adler, Leopold; Chen, Chunhe; Koutalos, Yiannis

    2017-01-01

    The accumulation of lipofuscin in the cells of the retinal pigment epithelium (RPE) is thought to play an important role in the development and progression of degenerative diseases of the retina. The bulk of RPE lipofuscin originates in reactions of the rhodopsin chromophore, retinal, with components of the photoreceptor outer segment. The 11-cis retinal isomer is generated in the RPE and supplied to rod photoreceptor outer segments where it is incorporated as the chromophore of rhodopsin. It is photoisomerized during light detection to all-trans and subsequently released by photoactivated rhodopsin as all-trans retinal, which is removed through reduction to all-trans retinol in a reaction requiring metabolic input in the form of NADPH. Both 11-cis and all-trans retinal can form lipofuscin precursor fluorophores in rod photoreceptor outer segments. Increased accumulation of lipofuscin has been suggested to result from excess formation of lipofuscin precursors due to buildup of all-trans retinal released by light exposure. In connection with this suggestion, the Abca4 transporter protein, an outer segment protein defects in which result in recessive Stargardt disease, has been proposed to promote the removal of all-trans retinal by facilitating its availability for reduction. To examine this possibility, we have measured the outer segment levels of all-trans retinal, all-trans retinol, and of lipofuscin precursors after bleaching by imaging the fluorescence of single rod photoreceptors isolated from wild type and Abca4−/− mice. We found that all-trans retinol and all-trans retinal levels increased after bleaching in both wild type and Abca4−/− rods. At all times after bleaching, there was no significant difference in all-trans retinal levels between the two strains. All-trans retinol levels were not significantly different between the two strains at early times, but were lower in Abca4−/− rods at times longer than 20 min after bleaching. Bleaching in the

  14. Importance of tunneling in H-abstraction reactions by OH radicals. The case of CH4 + OH studied through isotope-substituted analogs

    NASA Astrophysics Data System (ADS)

    Lamberts, T.; Fedoseev, G.; Kästner, J.; Ioppolo, S.; Linnartz, H.

    2017-03-01

    We present a combined experimental and theoretical study focussing on the quantum tunneling of atoms in the reaction between CH4 and OH. The importance of this reaction pathway is derived by investigating isotope substituted analogs. Quantitative reaction rates needed for astrochemical models at low temperature are currently unavailable both in the solid state and in the gas phase. Here, we study tunneling effects upon hydrogen abstraction in CH4 + OH by focusing on two reactions: CH4 + OD → CH3 + HDO and CD4 + OH → CD3 + HDO. The experimental study shows that the solid-state reaction rate RCH4 + OD is higher than RCD4 + OH at 15 K. Experimental results are accompanied by calculations of the corresponding unimolecular and bimolecular reaction rate constants using instanton theory taking into account surface effects. For the work presented here, the unimolecular reactions are particularly interesting as these provide insight into reactions following a Langmuir-Hinshelwood process. The resulting ratio of the rate constants shows that the H abstraction (kCH4 + OD) is approximately ten times faster than D-abstraction (kCD4 + OH) at 65 K. We conclude that tunneling is involved at low temperatures in the abstraction reactions studied here. The unimolecular rate constants can be used by the modeling community as a first approach to describe OH-mediated abstraction reactions in the solid phase. For this reason we provide fits of our calculated rate constants that allow the inclusion of these reactions in models in a straightforward fashion.

  15. Synthesis and structure of Cs[UO{sub 2}(SeO{sub 4})(OH)] . nH{sub 2}O (n = 1.5 or 1)

    SciTech Connect

    Serezhkina, L. B., E-mail: lserezh@ssu.samara.ru; Peresypkina, E. V.; Virovets, A. V.

    2010-05-15

    The synthesis and single-crystal X-ray diffraction study of Cs[UO{sub 2}(SeO{sub 4})(OH)] . 1.5H{sub 2}O (I) and Cs[UO{sub 2}(SeO{sub 4})(OH)] . H{sub 2}O (II) are performed. Compound I crystallizes in the monoclinic crystal system, a = 7.2142(2) A, b = 14.4942(4) A, c = 8.9270(3) A, {beta} = 112.706(1){sup o}, space group P2{sub 1}/m, Z = 4, and R = 0.0222. Compound II is monoclinic, a = 8.4549(2) A, b = 11.5358(3) A, c = 9.5565(2) A, {beta} = 113.273(1){sup o}, space group P2{sub 1}/c, Z = 4, and R = 0.0219. The main structural units of crystals I and IImore » are [UO{sub 2}(SeO{sub 4})(OH)]{sup -} layers which belong to the AT{sup 3}M{sup 2} crystal chemical group of uranyl complexes (A = UO{sub 2}{sup 2+}, T{sup 3} = SeO{sub 4}{sup 2-}, and M{sup 2} = OH{sup -}). In structure I, johannite-like layers are found. Structure II is a topological isomer of I. The two structures differ in the number of U(VI) atoms bound to the central atom by all bridging ligands.« less

  16. Chirality and ferromagnetism in NiBPO{sub 4}(OH){sub 2} containing helix edge-sharing NiO{sub 6} chains

    SciTech Connect

    Yang Tao; Ju Jing; Liao Fuhui

    2008-05-15

    Two isotypic borophosphates MBPO{sub 4}(OH){sub 2} (M=Mg, Ni) have been hydrothermally synthesized and structurally characterized by powder X-ray diffraction in the space group P3{sub 1}21. Nickel (or magnesium) atoms are octahedrally coordinated. The octahedra share edges to form helix chains around the three-fold screw-axis. Boron and phosphorus atoms are both tetrahedrally coordinated. The BO{sub 4} and PO{sub 4} tetrahedra are alternately connected, forming vierer-single chains. These two kinds of chains are intersected in the three-dimensional framework structure. NiBPO{sub 4}(OH){sub 2} can be considered as a quasi-one-dimensional magnet because the shortest Ni{sup 2+}-Ni{sup 2+} distance within the helix chain is aboutmore » 3.187(1) A, while the shortest inter-chain connection of the nickel ions is through a BO{sub 4} group (5.650(1) A). Both dc and alternating current (ac) susceptibilities and isothermal magnetization have been measured on powder sample. The intra- and inter-chain interactions are proved to be both ferromagnetic, and a long-range ordering is established below 2.2 K in NiBPO{sub 4}(OH){sub 2}. - Graphical abstract: Two isotypic borophosphates MBPO{sub 4}(OH){sub 2} (M=Mg, Ni) have been hydrothermally synthesized and structurally characterized by powder X-ray diffraction in the space group P3{sub 1}21. Nickel (or magnesium) atoms are octahedrally coordinated, which further share edges forming NiO{sub 6} chains around the three-fold screw-axis. Magnetic investigation of NiBPO{sub 4}(OH){sub 2} shows that it is a quasi-one-dimensional magnet, where the intra- and inter-chain interactions are proved to be both ferromagnetic, and a long-range ordering is established below 2.2 K.« less

  17. MODULATION OF SPONTANEOUS HIPPOCAMPAL SYNAPTIC EVENTS WITH 5-HYDROXYINDOLE, 4OH GTS-21, AND rAAV-MEDIATED α7 NICOTINIC RECEPTOR GENE TRANSFER

    PubMed Central

    Thinschmidt, Jeffrey S.; Ren, Ke; King, Michael A.; Meyer, Edwin M.; Papke, Roger L.

    2008-01-01

    One approach to treatment of negative cognitive effects associated with Alzheimer's disease and schizophrenia may involve activation of neuronal α7 nicotinic acetylcholine receptors (nAChRs). We used the α7-selective partial agonist 3-(4-hydroxy, 2-methoxy-benzylidene)anabaseine (4OH-GTS-21), the α7 modulator 5-hydroxyindole (5-HI), and recombinant adeno-associated virus (rAAV)–mediated α7 gene transfer in order to test the hypothesis whether combining these strategies would significantly increase indirect measures of α7 nAChR function, including measures of spontaneous synaptic events in CA1 pyramidal cells. 5-HI (1mM), and 5-HI (1 mM) + 4OH-GTS-21 (5 μM) increased the frequency of APV- and NBQX- sensitive currents, while 5-HI + 4OH-GTS-21 increased the frequency and amplitude of bicuculline-sensitive currents. Effects on EPSCs were blocked with tetrodotoxin (TTX) (1 μM), but not by methyllycaconitine (MLA) (50 nM). Neither TTX nor MLA reduced the potentiation of IPSC frequencies. However, TTX blocked, and in some cases MLA reduced, the potentiation of IPSC amplitudes. These data suggest that effects of 5-HI + 4OH-GTS-21 on EPSC frequency were associated with action potential-dependent transmitter release produced by 5HI, and that potentiation of IPSC amplitudes resulted at least in part, from activation of α7 nAChRs. Finally, rAAV–mediated α7 gene transfer did not alter the magnitude of effects produced by 5-HI or 5-HI + 4OH-GTS-21. Thus, although we previously showed direct measures of α7 nAChR function were enhanced by α7 gene transfer, indirect measures of α7 nAChRs function were not significantly enhanced by combining α7 gene transfer with either agonist activation or positive allosteric modulation of α7 nAChRs. PMID:18321476

  18. Interphotoreceptor retinoid-binding protein removes all-trans-retinol and retinal from rod outer segments, preventing lipofuscin precursor formation.

    PubMed

    Chen, Chunhe; Adler, Leopold; Goletz, Patrice; Gonzalez-Fernandez, Federico; Thompson, Debra A; Koutalos, Yiannis

    2017-11-24

    Interphotoreceptor retinoid-binding protein (IRBP) is a specialized lipophilic carrier that binds the all- trans and 11- cis isomers of retinal and retinol, and this facilitates their transport between photoreceptors and cells in the retina. One of these retinoids, all- trans- retinal, is released in the rod outer segment by photoactivated rhodopsin after light excitation. Following its release, all- trans- retinal is reduced by the retinol dehydrogenase RDH8 to all- trans- retinol in an NADPH-dependent reaction. However, all- trans- retinal can also react with outer segment components, sometimes forming lipofuscin precursors, which after conversion to lipofuscin accumulate in the lysosomes of the retinal pigment epithelium and display cytotoxic effects. Here, we have imaged the fluorescence of all- trans- retinol, all- trans- retinal, and lipofuscin precursors in real time in single isolated mouse rod photoreceptors. We found that IRBP removes all- trans- retinol from individual rod photoreceptors in a concentration-dependent manner. The rate constant for retinol removal increased linearly with IRBP concentration with a slope of 0.012 min -1 μm -1 IRBP also removed all- trans- retinal, but with much less efficacy, indicating that the reduction of retinal to retinol promotes faster clearance of the photoisomerized rhodopsin chromophore. The presence of physiological IRBP concentrations in the extracellular medium resulted in lower levels of all- trans- retinal and retinol in rod outer segments following light exposure. It also prevented light-induced lipofuscin precursor formation, but it did not remove precursors that were already present. These findings reveal an important and previously unappreciated role of IRBP in protecting the photoreceptor cells against the cytotoxic effects of accumulated all- trans- retinal.

  19. Structural Analysis and Dynamics of Retinal Chromophore in Dark and Meta I States of Rhodopsin from 2H NMR of Aligned Membranes

    PubMed Central

    Struts, Andrey V.; Salgado, Gilmar F. J.; Tanaka, Katsunori; Krane, Sonja; Nakanishi, Koji; Brown, Michael F.

    2016-01-01

    Summary Rhodopsin is a prototype for G protein-coupled receptors (GPCRs) that are implicated in many biological responses in humans. A site-directed 2H NMR approach was used for structural analysis of retinal within its binding cavity in the dark and pre-activated meta I states. Retinal was labeled with 2H at the C5, C9, or C13 methyl groups by total synthesis, and was used to regenerate the opsin apoprotein. Solid-state 2H NMR spectra were acquired for aligned membranes in the low-temperature lipid gel phase versus the tilt angle to the magnetic field. Data reduction assumed a static uniaxial distribution, and gave the retinylidene methyl bond orientations together with the alignment disorder (mosaic spread). The 2H NMR structure of 11-cis-retinal in the dark state revealed torsional twisting of the polyene chain and the β-ionone ring. The distorted retinylidene ligand undergoes restricted motion, as evinced by order parameters of ≈ 0.9 for the rapidly spinning C–C2H3 groups, with off-axial fluctuations of ≈ 15°. Retinal is accommodated within the rhodopsin binding pocket with a negative pre-twist about the C11=C12 double bond, which explains its rapid photochemistry and indicates the trajectory of the 11-cis to trans isomerization. For the cryotrapped meta I state, the 2H NMR structure showed a reduction of the polyene strain, whereas the β-ionone ring maintained its torsional twisting. Strain energy and dynamics of retinal are interpreted with regard to substituent control of receptor activation. Steric hindrance between trans retinal and Trp265 can trigger formation of the subsequent activated meta II state. Our results are pertinent to quantum and classical molecular mechanics simulations, and show how 2H NMR can be applied to ligands bound to GPCRs in relation to their characteristic mechanisms of action. PMID:17640664

  20. Dimerization deficiency of enigmatic retinitis pigmentosa-linked rhodopsin mutants

    NASA Astrophysics Data System (ADS)

    Ploier, Birgit; Caro, Lydia N.; Morizumi, Takefumi; Pandey, Kalpana; Pearring, Jillian N.; Goren, Michael A.; Finnemann, Silvia C.; Graumann, Johannes; Arshavsky, Vadim Y.; Dittman, Jeremy S.; Ernst, Oliver P.; Menon, Anant K.

    2016-10-01

    Retinitis pigmentosa (RP) is a blinding disease often associated with mutations in rhodopsin, a light-sensing G protein-coupled receptor and phospholipid scramblase. Most RP-associated mutations affect rhodopsin's activity or transport to disc membranes. Intriguingly, some mutations produce apparently normal rhodopsins that nevertheless cause disease. Here we show that three such enigmatic mutations--F45L, V209M and F220C--yield fully functional visual pigments that bind the 11-cis retinal chromophore, activate the G protein transducin, traffic to the light-sensitive photoreceptor compartment and scramble phospholipids. However, tests of scramblase activity show that unlike wild-type rhodopsin that functionally reconstitutes into liposomes as dimers or multimers, F45L, V209M and F220C rhodopsins behave as monomers. This result was confirmed in pull-down experiments. Our data suggest that the photoreceptor pathology associated with expression of these enigmatic RP-associated pigments arises from their unexpected inability to dimerize via transmembrane helices 1 and 5.

  1. Metal-organic frameworks assembled from lanthanide and 2,5-pyridinedicaboxylate with cubane-like [Ln4(OH)4] building units

    NASA Astrophysics Data System (ADS)

    Abdelbaky, Mohammed S. M.; Amghouz, Zakariae; Fernández-Zapico, Eva; García-Granda, Santiago; García, José R.

    2015-09-01

    Lanthanide-organic frameworks based on 2,5-pyridinedicaboxylate (25p) ligand, formulated as [Yb4(OH)4(25p)4(H2O)3]·H2O (25pYb), [Y4(OH)4(25p)4(H2O)3]·H2O (25pY-1) and [Y6(OH)8(25p)5(H2O)2] (25pY-2), have been obtained as single phases under hydrothermal conditions. 25pYb and 25pY-1 are isostructural, and crystallize in the triclinic space group, P-1, with a=8.6075(5) Å, b=14.8478(7) Å, c=15.9164(9) Å, α=86.277(4)°, β=80.196(5)°, γ=81.785(4)°, and a=8.7166(6) Å, b=14.966(1) Å, c=15.966(1) Å, α=86.260(6)°, β=80.036(6)°, γ=81.599(6)°, respectively. 25pY-2 crystallizes in the monoclinic space group, P21/c, with a=24.9117(17) Å, b=13.7340(8) Å, c=14.3385(10) Å, β=100.551(7)°. 25pYb and 25pY-2 have been structurally characterized by single-crystal X-ray diffraction. The 25pYb structure is based on tetranuclear cubane-like [Yb4(OH)4]8+ clusters, which are interconnected to eight neighbouring clusters through teen surrounding 25p ligands leading to neutral 3D framework, while the structure of 25pY-2 is based on two independent cuban-like [Y4(OH)4]8+ clusters, which are joined together through Y1 cation leading to the formation of hexanuclear [Y6(OH)8]10+ clusters, which in turn are joined via Y2 cation resulting in infinite inorganic chain extending along c-axis, and each chain is interconnected to six adjacent chains through 25p ligands leading finally to 3D framework. The luminescence properties of Eu3+ and Tb3+ doped 25pY-1 and 25pY-2 compounds have also been investigated. All materials has been characterized by powder X-ray diffraction, thermal analyses (TG-SDTA-MS), FTIR spectroscopy, C-H-N elemental analysis, scanning electron microscopy (SEM-EDX), and powder X-ray thermodiffraction.

  2. Collinear spin density wave order and anisotropic spin fluctuations in the frustrated J1-J2 chain magnet NaCuMoO4(OH )

    NASA Astrophysics Data System (ADS)

    Nawa, Kazuhiro; Yoshida, Makoto; Takigawa, Masashi; Okamoto, Yoshihiko; Hiroi, Zenji

    2017-11-01

    The phase diagram of the quasi-one-dimensional magnet NaCuMoO4(OH ) is established through single-crystal NMR and heat-capacity measurements. The 23Na and 1H NMR experiments indicate a spiral and a collinear spin density wave (SDW) order below and above Bc = 1.5-1.8 T, respectively. Moreover, in the paramagnetic state above the SDW transition temperature, the nuclear spin-lattice relaxation rate 1 /T1 indicates anisotropic spin fluctuations that have gapped excitations in the transverse spectrum but gapless ones in the longitudinal spectrum. These static and dynamic properties are well described by a theoretical model assuming quasi-one-dimensional chains with competing ferromagnetic nearest-neighbor interactions J1 and antiferromagnetic next-nearest-neighbor interactions J2 (J1-J2 chains). Because of the excellent crystal quality and good one-dimensionality, NaCuMoO4(OH ) is a promising compound to elucidate the unique physics of the frustrated J1-J2 chain.

  3. Metal–organic frameworks assembled from lanthanide and 2,5-pyridinedicaboxylate with cubane-like [Ln{sub 4}(OH){sub 4}] building units

    SciTech Connect

    Abdelbaky, Mohammed S.M.; Amghouz, Zakariae, E-mail: amghouz.uo@uniovi.es; Servicios Científico-Técnicos, University of Oviedo—CINN, Oviedo 33006

    2015-09-15

    Lanthanide–organic frameworks based on 2,5-pyridinedicaboxylate (25p) ligand, formulated as [Yb{sub 4}(OH){sub 4}(25p){sub 4}(H{sub 2}O){sub 3}]·H{sub 2}O (25pYb), [Y{sub 4}(OH){sub 4}(25p){sub 4}(H{sub 2}O){sub 3}]·H{sub 2}O (25pY-1) and [Y{sub 6}(OH){sub 8}(25p){sub 5}(H{sub 2}O){sub 2}] (25pY-2), have been obtained as single phases under hydrothermal conditions. 25pYb and 25pY-1 are isostructural, and crystallize in the triclinic space group, P-1, with a=8.6075(5) Å, b=14.8478(7) Å, c=15.9164(9) Å, α=86.277(4)°, β=80.196(5)°, γ=81.785(4)°, and a=8.7166(6) Å, b=14.966(1) Å, c=15.966(1) Å, α=86.260(6)°, β=80.036(6)°, γ=81.599(6)°, respectively. 25pY-2 crystallizes in the monoclinic space group, P2{sub 1}/c, with a=24.9117(17) Å, b=13.7340(8) Å, c=14.3385(10) Å, β=100.551(7)°. 25pYb and 25pY-2 have been structurally characterizedmore » by single-crystal X-ray diffraction. The 25pYb structure is based on tetranuclear cubane-like [Yb{sub 4}(OH){sub 4}]{sup 8+} clusters, which are interconnected to eight neighbouring clusters through teen surrounding 25p ligands leading to neutral 3D framework, while the structure of 25pY-2 is based on two independent cuban-like [Y{sub 4}(OH){sub 4}]{sup 8+} clusters, which are joined together through Y1 cation leading to the formation of hexanuclear [Y{sub 6}(OH){sub 8}]{sup 10+} clusters, which in turn are joined via Y2 cation resulting in infinite inorganic chain extending along c-axis, and each chain is interconnected to six adjacent chains through 25p ligands leading finally to 3D framework. The luminescence properties of Eu{sup 3+} and Tb{sup 3+} doped 25pY-1 and 25pY-2 compounds have also been investigated. All materials has been characterized by powder X-ray diffraction, thermal analyses (TG–SDTA–MS), FTIR spectroscopy, C–H–N elemental analysis, scanning electron microscopy (SEM-EDX), and powder X-ray thermodiffraction. - Graphical abstract: Nowadays, lanthanide–organic frameworks (LOFs

  4. Progressive dysfunction of the retinal pigment epithelium and retina due to increased VEGF-A levels

    PubMed Central

    Ablonczy, Zsolt; Dahrouj, Mohammad; Marneros, Alexander G.

    2014-01-01

    Patients with nonexudative (“dry”) age-related macular degeneration (AMD) frequently also develop neovascular (“wet”) AMD, suggesting a common pathomechanism. Increased vascular endothelial growth factor A (VEGF-A) has been implicated in the pathogenesis of choroidal neovascularization (CNV) in neovascular AMD, while its role in nonexudative AMD that manifests with progressive retinal pigment epithelium (RPE) and photoreceptor degeneration is not well defined. Mice with overall increased VEGF-A levels develop progressive morphological features of both forms of AMD, suggesting that an increase in VEGF-A has a direct age-dependent adverse effect on RPE and photoreceptor function independently of its CNV-promoting proangiogenic effect. Here we provide evidence for this hypothesis and show that morphological RPE abnormalities and retinal thinning in mice with increased VEGF-A levels correlate with progressive age-dependent attenuation of visual function with abnormal electroretinograms and reduced retinal rhodopsin levels. Retinoid profiling revealed a progressive reduction of 11-cis and all-trans retinal in the retinas of these mice, consistent with an impaired retinoid transport between the RPE and photoreceptors. These findings suggest that increased VEGF-A leads to an age-dependent RPE and retinal dysfunction that occurs also at sites where no CNV lesions form. The data support a central role of increased VEGF-A not only in the pathogenesis of neovascular but also of nonexudative AMD.—Ablonczy, Z., Dahrouj, M., Marneros, A. G. Progressive dysfunction of the retinal pigment epithelium and retina due to increased VEGF-A levels. PMID:24558195

  5. Single-Crystalline Hyperbranched Nanostructure of Iron Hydroxyl Phosphate Fe5(PO4)4(OH)3.2H2O for Highly Selective Capture of Phosphopeptides

    NASA Astrophysics Data System (ADS)

    Chen, Qun; Wei, Chengzhen; Zhang, Yizhou; Pang, Huan; Lu, Qingyi; Gao, Feng

    2014-01-01

    Single-crystalline hyperbranched nanostructures of iron hydroxyl phosphate Fe5(PO4)4(OH)3.2H2O (giniite) with orthorhombic phase were synthesized through a simple route. They have a well-defined dendrite fractal structure with a pronounced trunk and highly ordered branches. The toxicity test shows that the hyperbranched nanostructures have good biocompatibility and low toxicity level, which makes them have application potentials in life science. The study herein demonstrated that the obtained hyperbranched giniite nanostructures show highly selective capture of phosphopeptides and could be used as a kind of promising nanomaterial for the specific capture of phosphopeptides from complex tryptic digests with the detection of MALDI-TOF mass spectrometry.

  6. Employing linear tetranuclear [Zn4(COO)4(OH)2] clusters as building subunits to construct a new Zn(II) coordination polymer with tunable luminescent properties

    NASA Astrophysics Data System (ADS)

    Li, Wu-Wu; Zhang, Zun-Ting

    2016-02-01

    A new Zn(II) coordination polymer, [Zn2(btc) (biimpy) (OH)]n (1 H3btc = 1,3,5-benzenetricarboxylic acid, biimpy = 2,6-bis(1-imdazoly)pyridine) has been successfully synthesized and characterized by elemental analysis, powder single crystal X-ray diffraction analyses. Compound 1 features a 3D framework employing linear tetranuclear [Zn4(COO)4(OH)2] cluster as building subunits. Topological analysis reveals it represents a (3,10)-connected structural topology by viewing btc3-, linear tetranuclear clusters and biimpy as 3-connected nodes, 10-connected nodes, linear linkers, respectively. Moreover, the thermal stability and luminescent property of compound 1 have been well investigated.

  7. Chirality and magnetism in a novel series of isotypic borophosphates: M(II)[BPO4(OH)2] (M(II) = Mn, Fe, Co).

    PubMed

    Huang, Ya-Xi; Ewald, Bastian; Schnelle, Walter; Prots, Yurii; Kniep, Rüdiger

    2006-09-18

    Three novel isotypic borophosphates M(II)[BPO4(OH)2] (M(II) = Mn, Fe, Co) have been hydrothermally synthesized and structurally characterized. The isotypic compounds crystallize in the chiral space group P3(1)21 or P3(2)21. Their crystal structures are characterized by edge-sharing helical M(II)O6-octahedral chains wound around 3(1) or 3(2) screw axes (along [001]) interconnected by borophosphate single chains of alternating BO2(OH)2 and PO4 tetrahedra perpendicular to [001], resulting in three-dimensional framework structures. The helical M(II)O6-octahedral chains lead to low-dimensional magnetic properties.

  8. Thermal stability of rhodopsin and progression of retinitis pigmentosa: comparison of S186W and D190N rhodopsin mutants.

    PubMed

    Liu, Monica Yun; Liu, Jian; Mehrotra, Devi; Liu, Yuting; Guo, Ying; Baldera-Aguayo, Pedro A; Mooney, Victoria L; Nour, Adel M; Yan, Elsa C Y

    2013-06-14

    Over 100 point mutations in the rhodopsin gene have been associated with retinitis pigmentosa (RP), a family of inherited visual disorders. Among these, we focused on characterizing the S186W mutation. We compared the thermal properties of the S186W mutant with another RP-causing mutant, D190N, and with WT rhodopsin. To assess thermal stability, we measured the rate of two thermal reactions contributing to the thermal decay of rhodopsin as follows: thermal isomerization of 11-cis-retinal and hydrolysis of the protonated Schiff base linkage between the 11-cis-retinal chromophore and opsin protein. We used UV-visible spectroscopy and HPLC to examine the kinetics of these reactions at 37 and 55 °C for WT and mutant rhodopsin purified from HEK293 cells. Compared with WT rhodopsin and the D190N mutant, the S186W mutation dramatically increases the rates of both thermal isomerization and dark state hydrolysis of the Schiff base by 1-2 orders of magnitude. The results suggest that the S186W mutant thermally destabilizes rhodopsin by disrupting a hydrogen bond network at the receptor's active site. The decrease in the thermal stability of dark state rhodopsin is likely to be associated with higher levels of dark noise that undermine the sensitivity of rhodopsin, potentially accounting for night blindness in the early stages of RP. Further studies of the thermal stability of additional pathogenic rhodopsin mutations in conjunction with clinical studies are expected to provide insight into the molecular mechanism of RP and test the correlation between rhodopsin's thermal stability and RP progression in patients.

  9. Retinal Remodeling in Human Retinitis Pigmentosa

    PubMed Central

    Jones, B.W.; Pfeiffer, R.L.; Ferrell, W. D.; Watt, C.B.; Marmor, M.; Marc, R.E.

    2016-01-01

    Retinitis Pigmentosa (RP) in the human is a progressive, currently irreversible neural degenerative disease usually caused by gene defects that disrupt the function or architecture of the photoreceptors. While RP can initially be a disease of photoreceptors, there is increasing evidence that the inner retina becomes progressively disorganized as the outer retina degenerates. These alterations have been extensively described in animal models, but remodeling in humans has not been as well characterized. This study, using computational molecular phenotyping (CMP) seeks to advance our understanding of the retinal remodeling process in humans. We describe cone mediated preservation of overall topology, retinal reprogramming in the earliest stages of the disease in retinal bipolar cells, and alterations in both small molecule and protein signatures of neurons and glia. Furthermore, while Müller glia appear to be some of the last cells left in the degenerate retina, they are also one of the first cell classes in the neural retina to respond to stress which may reveal mechanisms related to remodeling and cell death in other retinal cell classes. Also fundamentally important is the finding that retinal network topologies are altered. Our results suggest interventions that presume substantial preservation of the neural retina will likely fail in late stages of the disease. Even early intervention offers no guarantee that the interventions will be immune to progressive remodeling. Fundamental work in the biology and mechanisms of disease progression are needed to support vision rescue strategies. PMID:27020758

  10. Human Blue Cone Opsin Regeneration Involves Secondary Retinal Binding with Analog Specificity.

    PubMed

    Srinivasan, Sundaramoorthy; Fernández-Sampedro, Miguel A; Morillo, Margarita; Ramon, Eva; Jiménez-Rosés, Mireia; Cordomí, Arnau; Garriga, Pere

    2018-03-27

    Human color vision is mediated by the red, green, and blue cone visual pigments. Cone opsins are G-protein-coupled receptors consisting of an opsin apoprotein covalently linked to the 11-cis-retinal chromophore. All visual pigments share a common evolutionary origin, and red and green cone opsins exhibit a higher homology, whereas blue cone opsin shows more resemblance to the dim light receptor rhodopsin. Here we show that chromophore regeneration in photoactivated blue cone opsin exhibits intermediate transient conformations and a secondary retinoid binding event with slower binding kinetics. We also detected a fine-tuning of the conformational change in the photoactivated blue cone opsin binding site that alters the retinal isomer binding specificity. Furthermore, the molecular models of active and inactive blue cone opsins show specific molecular interactions in the retinal binding site that are not present in other opsins. These findings highlight the differential conformational versatility of human cone opsin pigments in the chromophore regeneration process, particularly compared to rhodopsin, and point to relevant functional, unexpected roles other than spectral tuning for the cone visual pigments. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  11. Retinyl Ester Storage Particles (Retinosomes) from the Retinal Pigmented Epithelium Resemble Lipid Droplets in Other Tissues*

    PubMed Central

    Orban, Tivadar; Palczewska, Grazyna; Palczewski, Krzysztof

    2011-01-01

    Levels of many hydrophobic cellular substances are tightly regulated because of their potential cytotoxicity. These compounds tend to self-aggregate in cytoplasmic storage depots termed lipid droplets/bodies that have well defined structures that contain additional components, including cholesterol and various proteins. Hydrophobic substances in these structures become mobilized in a specific and regulated manner as dictated by cellular requirements. Retinal pigmented epithelial cells in the eye produce retinyl ester-containing lipid droplets named retinosomes. These esters are mobilized to replenish the visual chromophore, 11-cis-retinal, and their storage ensures proper visual function despite fluctuations in dietary vitamin A intake. But it remains unclear whether retinosomes are structures specific to the eye or similar to lipid droplets in other organs/tissues that contain substances other than retinyl esters. Thus, we initially investigated the production of these lipid droplets in experimental cell lines expressing lecithin:retinol acyltransferase, a key enzyme involved in formation of retinyl ester-containing retinosomes from all-trans-retinol. We found that retinosomes and oleate-derived lipid droplets form and co-localize concomitantly, indicating their intrinsic structural similarities. Next, we isolated native retinosomes from bovine retinal pigmented epithelium and found that their protein and hydrophobic small molecular constituents were similar to those of lipid droplets reported for other experimental cell lines and tissues. These unexpected findings suggest a common mechanism for lipid droplet formation that exhibits broad chemical specificity for the hydrophobic substances being stored. PMID:21454509

  12. Ab initio study on the low-lying excited states of retinal

    NASA Astrophysics Data System (ADS)

    Merchán, Manuela; González-Luque, Remedios

    1997-01-01

    Ab initio results for the electronic spectrum of all-trans-retinal and its truncated model 3-methyl-all-trans (10-s-cis)-2,4,6,8,10-undecapentaen-1-al are presented. The study includes geometry determination of the ground state. Vertical excitation energies have been computed using multiconfigurational second-order perturbation theory through the CASPT2 formalism. The lowest singlet excited state in gas phase is predicted to be of nπ* character. The lowest triplet state corresponds, however, to a ππ* state. The most intense feature of the spectrum is due to the strongly dipole-allowed ππ* transition, in accordance with the observed maximum in the one-photon spectra. The vertical excitation energies of the Bu- and Ag-like states are found close, the latter ≈1 eV higher than the maximum in the two-photon spectra. Solvent effects and nonvertical nature of the observed maximum in the two-photon spectra are invoked in rationalizing the deviation with respect to the best present estimate for the Ag-like state. In addition, qualitative aspects of the one-bond photoisomerization about the C11=C12 double bond of retinal are considered. The overall isomerization picture from 11-cis into all-trans-retinal, as taking place mainly along the triplet manifold, agrees with experimental evidence.

  13. Genetics Home Reference: retinitis pigmentosa

    MedlinePlus

    ... Email Facebook Twitter Home Health Conditions Retinitis pigmentosa Retinitis pigmentosa Printable PDF Open All Close All Enable Javascript to view the expand/collapse boxes. Description Retinitis pigmentosa is a group of related eye disorders that ...

  14. Retinal detachment repair

    MedlinePlus

    Scleral buckling; Vitrectomy; Pneumatic retinopexy; Laser retinopexy; Rhegmatogenous retinal detachment repair ... eye doctor can close the holes using a laser. This procedure is most often done in the ...

  15. Retinal Pigmented Epithelial Cells Obtained from Human Induced Pluripotent Stem Cells Possess Functional Visual Cycle Enzymes in Vitro and in Vivo*

    PubMed Central

    Maeda, Tadao; Lee, Mee Jee; Palczewska, Grazyna; Marsili, Stefania; Tesar, Paul J.; Palczewski, Krzysztof; Takahashi, Masayo; Maeda, Akiko

    2013-01-01

    Differentiated retinal pigmented epithelial (RPE) cells have been obtained from human induced pluripotent stem (hiPS) cells. However, the visual (retinoid) cycle in hiPS-RPE cells has not been adequately examined. Here we determined the expression of functional visual cycle enzymes in hiPS-RPE cells compared with that of isolated wild-type mouse primary RPE (mpRPE) cells in vitro and in vivo. hiPS-RPE cells appeared morphologically similar to mpRPE cells. Notably, expression of certain visual cycle proteins was maintained during cell culture of hiPS-RPE cells, whereas expression of these same molecules rapidly decreased in mpRPE cells. Production of the visual chromophore, 11-cis-retinal, and retinosome formation also were documented in hiPS-RPE cells in vitro. When mpRPE cells with luciferase activity were transplanted into the subretinal space of mice, bioluminance intensity was preserved for >3 months. Additionally, transplantation of mpRPE into blind Lrat−/− and Rpe65−/− mice resulted in the recovery of visual function, including increased electrographic signaling and endogenous 11-cis-retinal production. Finally, when hiPS-RPE cells were transplanted into the subretinal space of Lrat−/− and Rpe65−/− mice, their vision improved as well. Moreover, histological analyses of these eyes displayed replacement of dysfunctional RPE cells by hiPS-RPE cells. Together, our results show that hiPS-RPE cells can exhibit a functional visual cycle in vitro and in vivo. These cells could provide potential treatment options for certain blinding retinal degenerative diseases. PMID:24129572

  16. Crystal structure, equation of state, and elasticity of hydrous aluminosilicate phase, topaz-OH (Al2SiO4(OH)2) at high pressures

    NASA Astrophysics Data System (ADS)

    Mookherjee, Mainak; Tsuchiya, Jun; Hariharan, Anant

    2016-02-01

    We examined the equation of state and high-pressure elasticity of the hydrous aluminosilicate mineral topaz-OH (Al2SiO4(OH)2) using first principles simulation. Topaz-OH is a hydrous phase in the Al2O3-SiO2-H2O (ASH) ternary system, which is relevant for the mineral phase relations in the hydrated sedimentary layer of subducting slabs. Based on recent neutron diffraction experiments, it is known that the protons in the topaz-OH exhibit positional disorder with half occupancy over two distinct crystallographic sites. In order to adequately depict the proton environment in the topaz-OH, we examined five crystal structure models with distinct configuration for the protons in topaz-OH. Upon full geometry optimization we find two distinct space group, an orthorhombic Pbnm and a monoclinic P21/c for topaz-OH. The topaz-OH with the monoclinic P21/c space group has a lower energy compared to the orthorhombic Pbmn space group symmetry. The pressure-volume results for the monoclinic topaz-OH is well represented by a third order Birch-Murnaghan formulation, with V0mon = 348.63 (±0.04) Å3, K0mon = 164.7 (±0.04) GPa, and K0mon = 4.24 (±0.05). The pressure-volume results for the orthorhombic topaz-OH is well represented by a third order Birch-Murnaghan formulation, with V0orth = 352.47 (±0.04) Å3, K0orth = 166.4 (±0.06) GPa, and K0orth = 4.03 (±0.04). While the bulk moduli are very similar for both the monoclinic and orthorhombic topaz-OH, the shear elastic constants and the shear moduli are very sensitive to the position of the proton, orientation of the O-H dipole, and the space group symmetry. The S-wave anisotropy for the orthorhombic and monoclinic topaz-OH are also quite distinct. In the hydrated sedimentary layer of subducting slabs, transformation of a mineral assemblage consisting of coesite (SiO2) and diaspore (AlOOH) to topaz-OH (Al2SiO4(OH)2) is likely to be accompanied by an increase in density, compressional velocity, and shear wave velocity. However

  17. Quantitative examination of the photoisomerization of retinal iminium salts by high-field /sup 1/H NMR spectroscopy

    SciTech Connect

    Childs, R.F.; Shaw, G.S.

    1988-05-11

    High-field /sup 1/H NMR spectroscopy has been used to examine quantitatively the photoisomerization of the N-tert-butyl, N-n-butyl, and N,N-dimethyl all-trans iminium salts of retinal, 1, 2, and 3, respectively. The NMR analytical method developed, which was shown to be more reliable than previously used hydrolysis/HPLC techniques, allowed for the composition of the starting mixtures to be assayed. Under the conditions chosen, CD/sub 2/Cl/sub 2/ as solvent and ClO/sub 4//sup -/ as counterion at 22/sup 0/C, the various isomers of the retinylidene iminium salts were shown to be stable thermally. Irradiation of either 1, 2, or 3, using incident light ofmore » wavelengths 350, 436, or 468 nm, lead in each case to the formation of only the 11-cis isomers as initial photoproducts. The quantum efficiencies, corrected for back-reaction by extrapolation to zero conversion, of the isomerizations of 1, 2, and 3 to the corresponding 11-cis isomers are 0.25, 0.17, and 0.18, respectively. Estimates of the quantum yields for the reverse isomerizations are given.« less

  18. Infrared and Raman spectroscopic characterization of the borate mineral colemanite - CaB3O4(OH)3·H2O - implications for the molecular structure

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Xi, Yunfei; Scholz, Ricardo; Belotti, Fernanda Maria; Cândido Filho, Mauro

    2013-04-01

    Colemanite CaB3O4(OH)3·H2O is a secondary borate mineral formed from borax and ulexite in evaporate deposits of alkaline lacustrine sediments. The basic structure of colemanite contains endless chains of interlocking BO2(OH) triangles and BO3(OH) tetrahedrons with the calcium, water and extra hydroxide units interspersed between these chains. The Raman spectra of colemanite is characterized by an intense band at 3605 cm-1 assigned to the stretching vibration of OH units and a series of bands at 3182, 3300, 3389 and 3534 cm-1 assigned to water stretching vibrations. Infrared bands are observed in similar positions. The BO stretching vibrations of the trigonal and tetrahedral boron are characterized by Raman bands at 876, 1065 and 1084 cm-1. The OBO bending mode is defined by the Raman band at 611 cm-1. It is important to characterize the very wide range of borate minerals including colemanite because of the very wide range of applications of boron containing minerals.

  19. Boosted electrochemistry properties of Cu4[(OH)0.29Cl0.71](OH)6 hexagonal prisms by 3D-cage atomic configuration of (100) facet

    NASA Astrophysics Data System (ADS)

    Zhang, An; Teng, Fei; Zhang, Qiqi; Zhai, Yifei; Liu, Zailun; Liu, Zhe; Gu, Wenhao; Hao, Weiyi; Abideen, Zain Ul; Teng, Yiran

    2018-01-01

    The Cu4[(OH)0.29Cl0.71](OH)6 hexagonal prisms, nanoplates and nanosheets are prepared by a simple hydrothermal method, and we have mainly investigated their electrochemistry properties. At 31.25, 62.5, 125, 250 and 500 mAg-1, the discharge capacitances of hexagonal prisms (S0) electrode are 1186, 1023, 969, 934 and 918 mFg-1, respectively; whereas 547, 508, 469, 438 and 375 mFg-1 for hexagonal nanosheets (S10), respectively. The capacitance of 3-8 μm-long hexagonal prisms (0.25 m2g-1) is 2 times higher than that of 50-100 nm-thick hexagonal nanosheets (3.54 m2g-1), which is obviously beyond our imagination. The high capacitance of the former sample has been mainly attributed to the atom configuration of {100} facets and the high electrical conductivity. Compared with the hexagonal tunnel atom configuration of {001} facets, the three-dimensional (3D) cage atom configuration in {100} facets favors for the charge storage, thus leading to a higher capacitance of hexagonal prisms, which has rarely been reported yet. Further, the hexagonal prisms have a higher electrical conductivity than nanoplates and nanosheets, suggesting that the one-dimensional (1D) microstructure is beneficial to the electron transfer. This work enlightens us that the electrochemistry properties of materials can be improved by the exposed facets with unique atom configuration.

  20. Characterization of midazolam metabolism in locusts: the role of a CYP3A4-like enzyme in the formation of 1'-OH and 4-OH midazolam.

    PubMed

    Olsen, Line Rørbæk; Gabel-Jensen, Charlotte; Wubshet, Sileshi Gizachew; Kongstad, Kenneth Thermann; Janfelt, Christian; Badolo, Lassina; Hansen, Steen Honoré

    2016-01-01

    1. The metabolism of midazolam was investigated in vivo in locusts in order to evaluate the presence of an enzyme with functionality similar to human CYP3A4/5. 2. Hydroxylated metabolites of midazolam identical to human metabolites were detected in locusts and the apparent affinities (Km values) were in the same range as reported in humans (in locusts: 7-23 and 33-85 µM for the formation of the 1'-OH and 4-OH metabolites, respectively). 3. The formation of hydroxylated metabolites could successfully be inhibited by co-administration of ketoconazole, a known CYP3A4/5 inhibitor. 4. Besides phase I metabolites, a number of conjugated metabolites were detected using high-resolution mass spectrometry. The most abundant metabolites detected were structurally identified by (1)H NMR as two N-glucosides. NMR analysis strongly suggested that the glycosylation occurred at the two nitrogens (either one in each case) of the imidazole ring. 5. Distribution of midazolam and the glucose conjugates were successfully measured using desorption electrospray mass spectrometry imaging revealing time-dependent changes in distribution over time. 6. In conclusion, it appears that an enzyme with functionality similar to human CYP3A4/5 is present in locusts. However, it appears that conjugation with glucose is the main detoxification pathway of midazolam in locusts.

  1. Structural and magnetic characterization of the one-dimensional S = 5/2 antiferromagnetic chain system SrMn(VO 4)(OH)

    DOE PAGES

    Sanjeewa, Liurukara D.; Garlea, Vasile O.; McGuire, Michael A.; ...

    2016-06-06

    The descloizite-type compound, SrMn(VO 4)(OH), was synthesized as large single crystals (1-2mm) using a high-temperature high-pressure hydrothermal technique. X-ray single crystal structure analysis reveals that the material crystallizes in the acentric orthorhombic space group of P2 12 12 1 (no. 19), Z = 4. The structure exhibits a one-dimensional feature, with [MnO 4] chains propagating along the a-axis which are interconnected by VO 4 tetrahedra. Raman and infrared spectra were obtained to identify the fundamental vanadate and hydroxide vibrational modes. Magnetization data reveal a broad maximum at approximately 80 K, arising from one-dimensional magnetic correlations with intrachain exchange constant ofmore » J/k B = 9.97(3) K between nearest Mn neighbors and a canted antiferromagnetic behavior below T N = 30 K. Single crystal neutron diffraction at 4 K yielded a magnetic structure solution in the lower symmetry of the magnetic space group P2 1 with two unique chains displaying antiferromagnetically ordered Mn moments oriented nearly perpendicular to the chain axis. Lastly, the presence of the Dzyaloshinskii Moriya antisymmetric exchange interaction leads to a slight canting of the spins and gives rise to a weak ferromagnetic component along the chain direction.« less

  2. The molecular structure of the vanadate mineral mottramite [PbCu(VO4)(OH)] from Tsumeb, Namibia - A vibrational spectroscopic study

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Xi, Yunfei; López, Andrés; Corrêa, Lívia; Scholz, Ricardo

    2014-03-01

    We have studied a mineral sample of mottramite PbCu(VO4)(OH) from Tsumeb, Namibia using a combination of scanning electron microscopy with EDX, Raman and infrared spectroscopy. Chemical analysis shows principally the elements V, Pb and Cu. Ca occurs as partial substitution of Pb as well as P and As in substitution to V. Minor amounts of Si and Cr were also observed. The Raman band of mottramite at 829 cm-1, is assigned to the ν1 symmetric (VO4-) stretching mode. The complexity of the spectra is attributed to the chemical composition of the Tsumeb mottramite. The ν3 antisymmetric vibrational mode of mottramite is observed as very low intensity bands at 716 and 747 cm-1. The series of Raman bands at 411, 439, 451 cm-1 and probably also the band at 500 cm-1 are assigned to the (VO4-) ν2 bending mode. The series of Raman bands at 293, 333 and 366 cm-1 are attributed to the (VO4-) ν4 bending modes. The ν3, ν3 and ν4 regions are complex for both minerals and this is attributed to symmetry reduction of the vanadate unit from Td to Cs.

  3. Modern retinal laser therapy

    PubMed Central

    Kozak, Igor; Luttrull, Jeffrey K.

    2014-01-01

    Medicinal lasers are a standard source of light to produce retinal tissue photocoagulation to treat retinovascular disease. The Diabetic Retinopathy Study and the Early Treatment Diabetic Retinopathy Study were large randomized clinical trials that have shown beneficial effect of retinal laser photocoagulation in diabetic retinopathy and have dictated the standard of care for decades. However, current treatment protocols undergo modifications. Types of lasers used in treatment of retinal diseases include argon, diode, dye and multicolor lasers, micropulse lasers and lasers for photodynamic therapy. Delivery systems include contact lens slit-lamp laser delivery, indirect ophthalmocope based laser photocoagulation and camera based navigated retinal photocoagulation with retinal eye-tracking. Selective targeted photocoagulation could be a future alternative to panretinal photocoagulation. PMID:25892934

  4. Retinal Oximetry Discovers Novel Biomarkers in Retinal and Brain Diseases.

    PubMed

    Stefánsson, Einar; Olafsdottir, Olof Birna; Einarsdottir, Anna Bryndis; Eliasdottir, Thorunn Scheving; Eysteinsson, Thor; Vehmeijer, Wouter; Vandewalle, Evelien; Bek, Toke; Hardarson, Sveinn Hakon

    2017-05-01

    Biomarkers for several eye and brain diseases are reviewed, where retinal oximetry may help confirm diagnosis or measure severity of disease. These include diabetic retinopathy, central retinal vein occlusion (CRVO), retinitis pigmentosa, glaucoma, and Alzheimer's disease. Retinal oximetry is based on spectrophotometric fundus imaging and measures oxygen saturation in retinal arterioles and venules in a noninvasive, quick, safe manner. Retinal oximetry detects changes in oxygen metabolism, including those that result from ischemia or atrophy. In diabetic retinopathy, venous oxygen saturation increases and arteriovenous difference decreases. Both correlate with diabetic retinopathy severity as conventionally classified on fundus photographs. In CRVO, vein occlusion causes hypoxia, which is measured directly by retinal oximetry to confirm the diagnosis and measure severity. In both diseases, the change in oxygen levels is a consequence of disturbed blood flow with resulting tissue hypoxia and vascular endothelial growth factor (VEGF) production. In atrophic diseases, such as retinitis pigmentosa and glaucoma, retinal oxygen consumption is reduced and this is detected by retinal oximetry. Retinal oximetry correlates with visual field damage and retinal atrophy. It is an objective metabolic measure of the degree of retinal atrophy. Finally, the retina is part of the central nervous system tissue and reflects central nervous system diseases. In Alzheimer's disease, a change in retinal oxygen metabolism has been discovered. Retinal oximetry is a novel, noninvasive technology that opens the field of metabolic imaging of the retina. Biomarkers in metabolic, ischemic, and atrophic diseases of the retina and central nervous system have been discovered.

  5. Differential Diagnosis of Retinal Vasculitis

    PubMed Central

    Abu El-Asrar, Ahmed M.; Herbort, Carl P.; Tabbara, Khalid F.

    2009-01-01

    Retinal vaculitis is a sight-threatening inflammatory eye condition that involves the retinal vessels. Detection of retinal vasculitis is made clinically, and confirmed with the help of fundus fluorescein angiography. Active vascular disease is characterized by exudates around retinal vessels resulting in white sheathing or cuffing of the affected vessels. In this review, a practical approach to the diagnosis of retinal vasculitis is discussed based on ophthalmoscopic and fundus fluorescein angiographic findings. PMID:20404987

  6. Differential diagnosis of retinal vasculitis.

    PubMed

    Abu El-Asrar, Ahmed M; Herbort, Carl P; Tabbara, Khalid F

    2009-10-01

    Retinal vaculitis is a sight-threatening inflammatory eye condition that involves the retinal vessels. Detection of retinal vasculitis is made clinically, and confirmed with the help of fundus fluorescein angiography. Active vascular disease is characterized by exudates around retinal vessels resulting in white sheathing or cuffing of the affected vessels. In this review, a practical approach to the diagnosis of retinal vasculitis is discussed based on ophthalmoscopic and fundus fluorescein angiographic findings.

  7. The molecular structure of the phosphate mineral beraunite Fe2+Fe53+(PO4)4(OH)5ṡ4H2O - A vibrational spectroscopic study

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; López, Andrés; Scholz, Ricardo; Xi, Yunfei; Lana, Cristiano

    2014-07-01

    The mineral beraunite from Boca Rica pegmatite in Minas Gerais with theoretical formula Fe2+Fe53+(PO4)4(OH)5ṡ4H2O has been studied using a combination of electron microscopy with EDX and vibrational spectroscopic techniques. Raman spectroscopy identifies an intense band at 990 cm-1 and 1011 cm-1. These bands are attributed to the PO43- ν1 symmetric stretching mode. The ν3 antisymmetric stretching modes are observed by a large number of Raman bands. The Raman bands at 1034, 1051, 1058, 1069 and 1084 together with the Raman bands at 1098, 1116, 1133, 1155 and 1174 cm-1 are assigned to the ν3 antisymmetric stretching vibrations of PO43- and the HOPO32- units. The observation of these multiple Raman bands in the symmetric and antisymmetric stretching region gives credence to the concept that both phosphate and hydrogen phosphate units exist in the structure of beraunite. The series of Raman bands at 567, 582, 601, 644, 661, 673, and 687 cm-1 are assigned to the PO43- ν2 bending modes. The series of Raman bands at 437, 468, 478, 491, 503 cm-1 are attributed to the PO43- and HOPO32- ν4 bending modes. No Raman bands of beraunite which could be attributed to the hydroxyl stretching unit were observed. Infrared bands at 3511 and 3359 cm-1 are ascribed to the OH stretching vibration of the OH units. Very broad bands at 3022 and 3299 cm-1 are attributed to the OH stretching vibrations of water. Vibrational spectroscopy offers insights into the molecular structure of the phosphate mineral beraunite.

  8. A vibrational spectroscopic study of the phosphate mineral lulzacite Sr2Fe2+(Fe2+,Mg)2Al4(PO4)4(OH)10

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; López, Andrés; Belotti, Fernanda M.; Xi, Yunfei; Scholz, Ricardo

    2014-06-01

    The mineral lulzacite from Saint-Aubin des Chateaux mine, France, with theoretical formula Sr2Fe2+(Fe2+,Mg)2Al4(PO4)4(OH)10 has been studied using a combination of electron microscopy with EDX and vibrational spectroscopic techniques. Chemical analysis shows a Sr, Fe, Al phosphate with minor amounts of Ga, Ba and Mg. Raman spectroscopy identifies an intense band at 990 cm-1 with an additional band at 1011 cm-1. These bands are attributed to the PO43-ν1 symmetric stretching mode. The ν3 antisymmetric stretching modes are observed by a large number of Raman bands. The Raman bands at 1034, 1051, 1058, 1069 and 1084 together with the Raman bands at 1098, 1116, 1133, 1155 and 1174 cm-1 are assigned to the ν3 antisymmetric stretching vibrations of PO43- and the HOPO32- units. The observation of these multiple Raman bands in the symmetric and antisymmetric stretching region gives credence to the concept that both phosphate and hydrogen phosphate units exist in the structure of lulzacite. The series of Raman bands at 567, 582, 601, 644, 661, 673 and 687 cm-1 are assigned to the PO43-ν2 bending modes. The series of Raman bands at 437, 468, 478, 491, 503 cm-1 are attributed to the PO43- and HOPO32-ν4 bending modes. No Raman bands of lulzacite which could be attributed to the hydroxyl stretching unit were observed. Infrared bands at 3511 and 3359 cm-1 are ascribed to the OH stretching vibration of the OH units. Very broad bands at 3022 and 3299 cm-1 are attributed to the OH stretching vibrations of water. Vibrational spectroscopy offers insights into the molecular structure of the phosphate mineral lulzacite.

  9. Effect of Molar Concentration of NH4OH on Photocatalytic Activity in Preparation of Nanosized TiO2 Powder from Spent Titanium Chip by Sol-Gel Method.

    PubMed

    Lee, Hwan-Gyu; Lee, Young-Ho; Yun, Hyeon-Jun; Jo, Jang-Ho; Kim, Seong-Kyung; Yu, Hyeon-Jin; Kim, Ki-Joong; Kang, Byeong-Mo; Jeong, Woon-Jo; Chung, Min-Chul; Jung, Sang-Chul; Lee, Do-Jin; Ahn, Ho-Geun

    2016-05-01

    The TiO2 powder was prepared from the spent titanium chips by applying the sol-gel method. The spent titanium chip was dissolved in HCl solution, and then NH4OH solution was added. The molar concentration of NH4OH solution was 2 M, 4 M, 8 M, and 10 M. Obtained TiO2 powders were calcined at 200 degrees C, 400 degrees C, and 600 degrees C. The prepared TiO2 powder was characterized using a particle size analysis, BET surface area, and XRD analysis. The crystal structure of the TiO2 powder was rutile type and anatase. The highest BET surface area of TiO2 powder was 432.8 m2/g. The photocatalytic property of the TiO2 powder was evaluated as decomposition rate of methylene blue(MB) by using a liquid phase stirred reactor. UV source was a UV-A, and concentration of MB in most experiments was 8 ppm. The concentration of MB was measured by absorbance at 664 nm using UV spectroscopy. Photocatalytic efficiency of prepared TiO2 powder depended highly on concentration of NH4OH solution. The TiO2 powder prepared with 8 M-NH4OH solution showed the highest efficiency, the decomposition efficiency at decomposition time of 2 hr and MB concentration of pH 8 was 98%.

  10. Replacement of Oxygen by Sulfur in Small Organic Molecules. 3. Theoretical Studies on the Tautomeric Equilibria of the 2OH and 4OH-Substituted Oxazole and Thiazole and the 3OH and 4OH-Substituted Isoxazole and Isothiazole in the Isolated State and in Solution

    PubMed Central

    Nagy, Peter I.

    2016-01-01

    This follow-up paper completes the author’s investigations to explore the in-solution structural preferences and relative free energies of all OH-substituted oxazole, thiazole, isoxazole, and isothiazole systems. The polarizable continuum dielectric solvent method calculations in the integral-equation formalism (IEF-PCM) were performed at the DFT/B97D/aug-cc-pv(q+(d))z level for the stable neutral tautomers with geometries optimized in dichloromethane and aqueous solution. With the exception of the predictions for the predominant tautomers of the 3OH isoxazole and isothiazole, the results of the IEF-PCM calculations for identifying the most stable tautomer of the given species in the two selected solvents agreed with those from experimental investigations. The calculations predict that the hydroxy proton, with the exception for the 4OH isoxazole and 4OH isothiazole, moves preferentially to the ring nitrogen or to a ring carbon atom in parallel with the development of a C=O group. The remaining, low-fraction OH tautomers will not be observable in the equilibrium compositions. Relative solvation free energies obtained by the free energy perturbation method implemented in Monte Carlo simulations are in moderate accord with the IEF-PCM results, but consideration of the ΔGsolv/MC values in calculating ΔGstot maintains the tautomeric preferences. It was revealed from the Monte Carlo solution structure analyses that the S atom is not a hydrogen-bond acceptor in any OH-substituted thiazole or isothiazole, and the OH-substituted isoxazole and oxazole ring oxygens may act as a weak hydrogen-bond acceptor at most. The molecules form 1.0−3.4 solute−water hydrogen bonds in generally unexplored numbers at some specific solute sites. Nonetheless, hydrogen-bond formation is favorable with the NH, C=O and OH groups. PMID:27409605

  11. Superficial retinal precipitates in patients with syphilitic retinitis.

    PubMed

    Fu, Evelyn X; Geraets, Ryan L; Dodds, Emilio M; Echandi, Laura V; Colombero, Daniel; McDonald, H Richard; Jumper, J Michael; Cunningham, Emmett T

    2010-01-01

    The purpose of this study was to describe the occurrence of superficial retinal precipitates in patients with syphilitic retinitis. This was a retrospective, observational case series of nine eyes of eight patients with syphilitic retinitis associated with superficial retinal precipitates. The clinical, photographic, angiographic, and laboratory records were reviewed. Characteristics and treatment response of these superficial retinal precipitates were observed. All patients were Caucasian men, including 5 men who have sex with men (62.5%) and 6 (75.0%) who were positive for human immunodeficiency virus. None of the patients were previously diagnosed with syphilis. All patients developed panuveitis and a distinctly diaphanous or ground-glass retinitis associated with creamy yellow superficial retinal precipitates. In 3 patients (37.5%), the retinitis had a distinctive wedge-shaped appearance. Five patients (62.5%) had associated retinal vasculitis, 3 (37.5%) had serous retinal detachment, 2 (22.2%) had intraretinal hemorrhage, and 2 (22.2%) had papillitis. Within 2 weeks of initiating intravenous penicillin treatment, 7 patients (87.5%) experienced visual recovery to >or= 20/40. All affected eyes showed rapid resolution of clinical signs with minimal alternations of the retinal pigment epithelium in areas of prior retinitis after completion of antibiotic therapy. Characteristic superficial retinal precipitates may occur over areas of syphilitic retinitis. Improved recognition of this highly suggestive clinical sign may aid in early diagnosis and treatment.

  12. Retinal oximetry in patients with ischaemic retinal diseases.

    PubMed

    Rilvén, Sandra; Torp, Thomas Lee; Grauslund, Jakob

    2017-03-01

    The retinal oximeter is a new tool for non-invasive measurement of retinal oxygen saturation in humans. Several studies have investigated the associations between retinal oxygen saturation and retinal diseases. In the present systematic review, we examine whether there are associations between retinal oxygen saturation and retinal ischaemic diseases. We used PubMed and Embase to search for retinal oxygen saturation and retinal ischaemic diseases. Three separate searches identified a total of 79 publications. After two levels of manual screening, 10 studies were included: six about diabetic retinopathy (DR) and four about retinal vein occlusion. No studies about retinal artery occlusion were included. In diabetes, all studies found that increases in retinal venous oxygen saturation (rvSatO 2 ) were associated with present as well as increasing levels of DR. Four of six studies also found increased retinal arterial oxygen saturation (raSatO 2 ) in patients with DR. In patients with central retinal vein occlusion (CRVO), all studies found that rvSatO 2 was reduced, but raSatO 2 remained unchanged. Branch retinal vein occlusion was not associated with changes in retinal oxygen saturation, but this was based on a single study. In conclusion, DR is associated with increased rvSatO 2 and might also be related to increased raSatO 2 . Central retinal vein occlusion (CRVO) is correlated with increased rvSatO 2 but unrelated to raSatO 2 . Prospective studies are needed to expand these findings. These would tell whether retinal oximetry could be a potential tool for screening or a biomarker of treatment outcome in patients with ischaemic retinal diseases. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  13. Unilateral retinitis pigmentosa.

    PubMed

    Bhattarai, D; Paudel, N; Adhikari, P; Gnyawali, S; Joshi, S N

    2015-01-01

    To report a rare case of unilateral retinitis pigmentosa and to present the clinical features, and findings of multifocal ERG and visual field of this case. A 70-year-old-female diagnosed as Retinitis Pigmentosa in right eye 7 years back, presented with further gradual painless diminution of vision in the very eye and without any similar symptoms in left eye. On examination, the findings (including multifocal ERG and visual field) suggested the features of retinitis pigmentosa in her right eye, while the other eye being unaffected. In this rare case, the distinct features of retinitis pigmentosa are seen only in one eye, and this can be further confirmed from multifocal ERG and visual field. © NEPjOPH.

  14. Learning about Retinitis Pigmentosa

    MedlinePlus

    Skip to main content Learning about Retinitis Pigmentosa Enter Search Term(s): Español Research Funding An Overview Bioinformatics Current Grants Education and Training Funding Extramural Research News Features Funding Divisions Funding ...

  15. Retinal dysplasia of holoprosencephaly.

    PubMed

    Gorovoy, Ian R; Layer, Noelle; de Alba Campomanes, Alejandra G

    2014-03-04

    Retinal dysplasia occurs in the setting of sporadic and syndromic holoprosencephaly, which often has associated ocular malformations. The pathology of this dysplasia, which includes rosettes, has been previously described. However, its funduscopic findings have not been well documented. The authors present the fundus images of a patient with severe holoprosencephaly with retinal dysplasia and bilateral optic nerve colobomas that resulted in death 2 weeks after birth. Copyright 2014, SLACK Incorporated.

  16. Retinal detachment in pseudophakia.

    PubMed

    Galin, M A; Poole, T A; Obstbaum, S A

    1979-07-01

    In a series of cataract patients excluding myopic individuals, under age 60 years, and cases in which vitreous loss occurred, retinal detachment was no less frequent after intracapsular cataract extraction and Sputnik iris supported lenses than in controls. Both groups were followed up for a minimum of two years. The detachments predominantly occurred from retinal breaks in areas of the retina that looked normal preoperatively.

  17. Genetics in Retinal Diseases.

    PubMed

    Riaz, Moeen; Baird, Paul N

    2016-01-01

    The phenotypic presentation of retinal diseases is typically underpinned by the presence of genetic variation represented by either polymorphic changes, mutations, copy number variations or epigenetic changes. Retinal dystrophies can broadly be divided into two forms, either monogenic (single-gene) or complex (multifactorial) diseases. Recent advances in molecular techniques such as genome-wide association studies and next-generation sequencing have revolutionized the discovery of genetic variants associated with different retinal disorders, including retinitis pigmentosa and age-related macular degeneration. Understanding the genetic profile of the disease not only helps in diagnostics but also in gene therapy, as recently shown for Leber's congenital amaurosis. Following the elucidation of many genetic features of retinal diseases, the task is now to make sense of this large amount of data to better understand as well as experimentally prove the physiological process of the retinal disease genes and the mechanisms behind the diseases. This in turn will lead to improved gene-based therapies and personalize treatments for patients. © 2016 S. Karger AG, Basel.

  18. Giant retinal tears.

    PubMed

    Shunmugam, Manoharan; Ang, Ghee Soon; Lois, Noemi

    2014-01-01

    A giant retinal tear (GRT) is a full-thickness neurosensory retinal break that extends circumferentially around the retina for three or more clock hours in the presence of a posteriorly detached vitreous. Its incidence in large population-based studies has been estimated as 1.5% of rhegmatogenous retinal detachments, with a significant male preponderance, and bilaterality in 12.8%. Most GRTs are idiopathic, with trauma, hereditary vitreoretinopathies and high myopia each being causative in decreasing frequency. The vast majority of GRTs are currently managed with a pars plana vitrectomy; the use of adjunctive circumferential scleral buckling is debated, but no studies have shown a clear anatomical or visual advantage with its use. Similarly, silicone oil tamponade does not influence long-term outcomes when compared with gas. Primary and final retinal reattachment rates are achieved in 88% and 95% of patients, respectively. Even when the retina remains attached, however, visual recovery may be limited. Furthermore, fellow eyes of patients with a GRT are at higher risk of developing retinal tears and retinal detachment. Prophylactic treatment under these circumstances may be considered but there is no firm evidence of its efficacy at the present time. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Atom-radical reaction dynamics of O(3P)+C3H5→C3H4+OH: Nascent rovibrational state distributions of product OH

    NASA Astrophysics Data System (ADS)

    Park, Jong-Ho; Lee, Hohjai; Kwon, Han-Cheol; Kim, Hee-Kyung; Choi, Young-Sang; Choi, Jong-Ho

    2002-08-01

    The reaction dynamics of ground-state atomic oxygen [O(3P)] with allyl radicals (C3H5) has been investigated by applying a combination of crossed beams and laser induced fluorescence techniques. The reactants O(3P) and C3H5 were produced by the photodissociation of NO2 and the supersonic flash pyrolysis of precursor allyl iodide, respectively. A new exothermic channel of O(3P)+C3H5→C3H4+OH was observed and the nascent internal state distributions of the product OH (X 2Π:υ″=0,1) showed substantial bimodal internal excitations of the low- and high-N″ components without Λ-doublet and spin-orbit propensities in the ground and first excited vibrational states. With the aid of the CBS-QB3 level of ab initio theory and Rice-Ramsperger-Kassel-Marcus calculations, it is predicted that on the lowest doublet potential energy surface the major reaction channel of O(3P) with C3H5 is the formation of acrolein (CH2CHCHO)+H, which is consistent with the previous bulk kinetic experiments performed by Gutman et al. [J. Phys. Chem. 94, 3652 (1990)]. The counterpart C3H4 of the probed OH product in the title reaction is calculated to be allene after taking into account the factors of reaction enthalpy, barrier height and the number of intermediates involved along the reaction pathway. On the basis of population analyses and comparison with prior calculations, the statistical picture is not suitable to describe the reactive atom-radical scattering processes, and the dynamics of the title reaction is believed to proceed through two competing dynamical pathways. The major low N″-components with significant vibrational excitation may be described by the direct abstraction process, while the minor but extraordinarily hot rotational distribution of high N″-components implies that some fraction of reactants is sampled to proceed through the indirect short-lived addition-complex forming process.

  20. Solid-State 2H NMR Spectroscopy of Retinal Proteins in Aligned Membranes

    PubMed Central

    Brown, Michael F.; Heyn, Maarten P.; Job, Constantin; Kim, Suhkmann; Moltke, Stephan; Nakanishi, Koji; Nevzorov, Alexander A.; Struts, Andrey V.; Salgado, Gilmar F. J.; Wallat, Ingrid

    2016-01-01

    Solid-state 2H NMR spectroscopy gives a powerful avenue to investigating the structures of ligands and cofactors bound to integral membrane proteins. For bacteriorhodopsin (bR) and rhodopsin retinal was site-specifically labeled by deuteration of the methyl groups, followed by regeneration of the apoprotein. 2H NMR studies of aligned membrane samples were conducted under conditions where rotational and translational diffusion of the protein were absent on the NMR time scale. The theoretical lineshape treatment involved a static axial distribution of rotating C–C2H3 groups about the local membrane frame, together with the static axial distribution of the local membrane normal relative to the average normal. Simulation of solid-state 2H NMR lineshapes gave both the methyl group orientations and the alignment disorder (mosaic spread) of the membrane stack. The methyl bond orientations provided the angular restraints for structural analysis. In the case of bR the retinal chromophore is nearly planar in the dark- and all-trans light-adapted states, as well upon isomerization to 13-cis in the M state. The C13-methyl at the "business end" of the chromophore changes its orientation to the membrane upon photon absorption, moving towards W182 thus driving the proton pump in energy conservation. Moreover rhodopsin was studied as a prototype for G protein-coupled receptors (GPCRs) implicated in many biological responses in humans. In contrast to bR, the retinal chromophore of rhodopsin has an 11-cis conformation and is highly twisted in the dark state. Three sites of interaction affect the torsional deformation of retinal, viz. the protonated Schiff base with its carboxylate counterion; the C9-methyl group of the polyene; and the β-ionone ring within its hydrophobic pocket. For rhodopsin strain energy and dynamics of retinal as established by 2H NMR are implicated in substituent control of activation. Retinal is locked in a conformation that is twisted in the direction of

  1. Progressive outer retinal necrosis-like retinitis in immunocompetent hosts.

    PubMed

    Chawla, Rohan; Tripathy, Koushik; Gogia, Varun; Venkatesh, Pradeep

    2016-08-10

    We describe two young immunocompetent women presenting with bilateral retinitis with outer retinal necrosis involving posterior pole with centrifugal spread and multifocal lesions simulating progressive outer retinal necrosis (PORN) like retinitis. Serology was negative for HIV and CD4 counts were normal; however, both women were on oral steroids at presentation for suspected autoimmune chorioretinitis. The retinitis in both eyes responded well to oral valaciclovir therapy. However, the eye with the more fulminant involvement developed retinal detachment with a loss of vision. Retinal atrophy was seen in the less involved eye with preservation of vision. Through these cases, we aim to describe a unique evolution of PORN-like retinitis in immunocompetent women, which was probably aggravated by a short-term immunosuppression secondary to oral steroids. 2016 BMJ Publishing Group Ltd.

  2. Photovoltaic retinal prosthesis

    NASA Astrophysics Data System (ADS)

    Loudin, James; Mathieson, Keith; Kamins, Ted; Wang, Lele; Galambos, Ludwig; Huie, Philip; Sher, Alexander; Harris, James; Palanker, Daniel

    2011-03-01

    Electronic retinal prostheses seek to restore sight to patients suffering from retinal degenerative disorders. Implanted electrode arrays apply patterned electrical stimulation to surviving retinal neurons, producing visual sensations. All current designs employ inductively coupled coils to transmit power and/or data to the implant. We present here the design and initial testing of a photovoltaic retinal prosthesis fabricated with a pixel density of up to 177 pixels/mm2. Photodiodes within each pixel of the subretinal array directly convert light to stimulation current, avoiding the use of bulky coil implants, decoding electronics, and wiring, and thereby reducing surgical complexity. A goggles-mounted camera captures the visual scene and transmits the data stream to a pocket processor. The resulting images are projected into the eyes by video goggles using pulsed, near infrared (~900 nm) light. Prostheses with three pixel densities (15, 55, and 177 pix/mm2) are being fabricated, and tests indicate a charge injection limit of 1.62 mC/cm2 at 25Hz. In vitro tests of the photovoltaic retinal stimulation using a 512-element microelectrode array have recorded stimulated spikes from the ganglion cells, with latencies in the 1-100ms range, and with peak irradiance stimulation thresholds varying from 0.1 to 1 mW/mm2. With 1ms pulses at 25Hz the average irradiance is more than 100 times below the IR retinal safety limit. Elicited retinal response disappeared upon the addition of synaptic blockers, indicating that the inner retina is stimulated rather than the ganglion cells directly, and raising hopes that the prosthesis will preserve some of the retina's natural signal processing.

  3. Pharmacokinetic Study of Praziquantel Enantiomers and Its Main Metabolite R-trans-4-OH-PZQ in Plasma, Blood and Dried Blood Spots in Opisthorchis viverrini-Infected Patients.

    PubMed

    Meister, Isabel; Kovac, Jana; Duthaler, Urs; Odermatt, Peter; Huwyler, Jörg; Vanobberghen, Fiona; Sayasone, Somphou; Keiser, Jennifer

    2016-05-01

    Praziquantel (PZQ) is the treatment of choice for infections with the liver fluke Opisthorchis viverrini, a major health problem in Southeast Asia. However, pharmacokinetic (PK) studies investigating the disposition of PZQ enantiomers (R- and S-PZQ) and its main metabolite, R-trans-4-OH-PZQ, in diseased patients are lacking. The implementation of a dried blood spot (DBS) sampling technique would ease the performance of PK studies in remote areas without clinical facilities. The aim of the present study is to provide data on the disposition of PZQ enantiomers and R-trans-4-OH-PZQ in opisthorchiasis patients and to validate the use of DBS compared to plasma and blood sampling. PZQ was administered to nine O. viverrini-infected patients at 3 oral doses of 25 mg/kg in 4 h intervals. Plasma, blood and DBS were simultaneously collected at selected time points from 0 to 24 h post-treatment. PK parameters were determined using non-compartmental analysis. Drug concentrations and areas under the curve (AUC0-24h) measured in the 3 matrices were compared using Bland-Altman analysis. We observed plasma AUC0-24hs of 1.1, 9.0 and 188.7 μg/ml*h and half-lives of 1.1, 3.3 and 6.4 h for R-PZQ, S-PZQ and R-trans-4-OH, respectively. Maximal plasma concentrations (Cmax) of 0.2, 0.9 and 13.9 μg/ml for R-PZQ, S-PQZ and R-trans-4-OH peaked at 7 h for PZQ enantiomers and at 8.7 h for the metabolite. Individual drug concentration measurements and patient AUC0-24hs displayed ratios of blood or DBS versus plasma between 79-94% for R- and S-PZQ, and between 108-122% for R-trans-4-OH. Pharmacodynamic (PD) in vitro studies on PZQ enantiomers and R-trans-4-OH-PZQ are necessary to be able to correlate PK parameters with efficacy. DBS appears to be a valid alternative to conventional venous sampling for PK studies in PZQ-treated patients.

  4. Positive modulation of alpha7 nAChR responses in rat hippocampal interneurons to full agonists and the alpha7-selective partial agonists, 4OH-GTS-21 and S 24795

    PubMed Central

    López-Hernández, Gretchen Y.; Thinschmidt, Jeffrey S.; Morain, Philippe; Trocme-Thibierge, Caryn; Kem, William R.; Soti, Ferenc; Papke, Roger L.

    2009-01-01

    Summary One approach for the identification of therapeutic agents for Alzheimer's disease has focused on the research of α7 nAChR-selective agonists such as the partial agonists 3-(4-hydroxy,2-methoxybenzylidene)anabaseine (4OH-GTS-21) and, more recently, 2-[2-(4-bromophenyl)-2-oxoethyl]-1-methyl pyridinium (S 24795). An alternative approach for targeting α7 nAChR has been the development of positive modulators for this receptor. In this study we examined the interactions between full or partial agonists and positive modulators of α7 nAChRs in situ in brain tissue. Three positive modulators were used, 5-hydroxyindole (5-HI), 1-(5-chloro-2,4-dimethoxy-phenyl)-3-(5-methyl-isoxanol-3-yl)-urea (PNU-120596), and genistein. Whole-cell recordings were performed in stratum radiatum interneurons from rat brain slices. Hippocampal interneurons were stimulated by ACh, choline, S 24795, or 4OH-GTS-21, before and after bath perfusion with the positive modulators. 5-HI was not effective at potentiating 200 μM 4OH-GTS-21-evoked responses, however 5-HI induced a sustained potentiation of responses evoked by 30 μM 4OH-GTS-21. When 1 mM ACh and 200 μM 4OH-GTS-21 were applied alternately α7-mediated responses to both agonists were reduced, suggesting that high concentration of 4OH-GTS-21 produces residual inhibition or desensitization and that 5-HI is not effective at overcoming receptor desensitization. Similar results were obtained with α7 receptors expressed in Xenopus oocytes. Interestingly, responses evoked by S 24795 were potentiated by 5-HI but not by genistein. Additionally, PNU-120596 was able to potentiate α7-mediated responses, regardless of the nature of the agonist. We demonstrated that the potentiation of α7 nAChR response would depend on the nature and the effective concentration of the agonist involved and its particular interaction with the positive modulator. PMID:19705574

  5. Intracellular Signalling in Retinal Ischemia

    DTIC Science & Technology

    1990-07-01

    36) However, vascularization of the RPE is not known to occur in human diseases of photoreceptor degeneration, such as retinitis pigmentosa ...A.C. (1986) Retinitis pigmentosa and retinal neovascularization. Ophthalmology 91, 1599- 1603. Figure la: Control rat retina, 8 weeks of age, central...TITLE (Include Security Classification) Intracellular Signalling in Retinal Ischemia 12. PERSONAL AUTHOR(S) Burns, Margaret Sue; Bellhorn, Roy William

  6. Zincoberaunite, ZnFe3+ 5(PO4)4(OH)5ṡ6H2O, a new mineral from the Hagendorf South pegmatite, Germany

    NASA Astrophysics Data System (ADS)

    Chukanov, Nikita V.; Pekov, Igor V.; Grey, Ian E.; Price, Jason R.; Britvin, Sergey N.; Krzhizhanovskaya, Maria G.; Kampf, Anthony R.; Dünkel, Bernhard; Keck, Erich; Belakovskiy, Dmitry I.; MacRae, Colin M.

    2017-06-01

    The new mineral zincoberaunite, ideally ZnFe3+ 5(PO4)4(OH)5·6H2O, the Zn analogue of beraunite, is found in the Hagendorf South granitic pegmatite, Hagendorf, Bavaria, Germany, in two associations: (1) with potassium feldspar, quartz, jungite, phosphophyllite and mitridatite (the holotype) and (2) with flurlite, plimerite, Zn-bearing beraunite, schoonerite, parascholzite/scholzite, robertsite and altered phosphophyllite (the cotype). Zincoberaunite occurs as radial or randomly oriented aggregates of flexible fibers up to 1.5 mm long and up to 3 μm thick. D calc is 2.92 g/cm3 for the holotype and 2.94 g/cm3 for the cotype. Zincoberaunite is optically biaxial (-), α = 1.745(5), β = 1.760(5), γ = 1.770(5), 2 V meas = 80(5)°. Chemical composition of the holotype (electron probe microanalyser; H2O by gas chromatography of ignition products) is: MgO 0.28 wt%, CaO 0.47 wt%, ZnO 7.36 wt%, Al2O3 0.88 wt%, Fe2O3 42.42 wt%, P2O5 31.63 wt%, H2O 16.2 wt%, total 101.1 wt%. The empirical formula calculated on the basis of 27 oxygen atoms per formula unit is (Zn0.83Ca0.08Mg0.06)∑0.97(Fe3+ 4.88Al0.16)∑5.04(PO4)4.09(OH)4.78 · 5.86H2O. Zincoberaunite is monoclinic, space group C2 /c; refined unit cell parameters (for the holotype at room temperature and the cotype at 100 K, respectively) are: a 20.837(2) and 20.836(4), b 5.1624(4) and 5.148(1), c 19.250(1) and 19.228(4) Å, β 93.252(5) and 93.21(3)°, V 2067.3(3) and 2059.2(7) Å3, Z = 4. The crystal structure of the holotype specimen has been refined by the Rietveld method ( R p = 0.30 %; R B = 0.18 %) whereas the structure of the cotype has been solved from the single crystal data and refined to R 1 = 0.056 based on 1900 unique reflections with I > 2σ( I). The strongest reflections of the powder X-ray diffraction pattern of the holotype specimen [( d, Å) ( I, %) ( hkl)] are: 10.37 (100) (200), 9.58 (32) (002), 7.24 (26) (20-2), 4.817 (22) (111), 4.409 (13) (112), 3.483 (14) (11-4, 600), 3.431 (14) (404), 3.194 (15

  7. Attikaite, Ca3Cu2Al2(AsO4)4(OH)4 · 2H2O, a new mineral species

    NASA Astrophysics Data System (ADS)

    Chukanov, N. V.; Pekov, I. V.; Zadov, A. E.

    2007-12-01

    Attikaite, a new mineral species, has been found together with arsenocrandalite, arsenogoyazite, conichalcite, olivenite, philipsbornite, azurite, malachite, carminite, beudantite, goethite, quartz, and allophane at the Christina Mine No. 132, Kamareza, Lavrion District, Attiki Prefecture (Attika), Greece. The mineral is named after the type locality. It forms spheroidal segregations (up to 0.3 mm in diameter) consisting of thin flexible crystals up to 3 × 20 × 80 μm in size. Its color is light blue to greenish blue, with a pale blue streak. The Mohs’ hardness is 2 to 2.5. The cleavage is eminent mica-like parallel to {001}. The density is 3.2(2) g/cm3 (measured in heavy liquids) and 3.356 g/cm3 (calculated). The wave numbers of the absorption bands in the infrared spectrum of attikaite are (cm-1; sh is shoulder; w is a weak band): 3525 sh, 3425, 3180, 1642, 1120 w, 1070 w, 1035 w, 900 sh, 874, 833, 820, 690 w, 645 w, 600 sh, 555, 486, 458, and 397. Attikaite is optically biaxial, negative, α = 1.642(2), β = γ = 1.644(2) ( X = c) 2 V means = 10(8)°, and 2 V calc = 0°. The new mineral is microscopically colorless and nonpleochroic. The chemical composition (electron microprobe, average over 4 point analyses, wt %) is: 0.17 MgO, 17.48 CaO, 0.12 FeO, 16.28 CuO, 10.61 Al2O3, 0.89 P2O5, 45.45 As2O5, 1.39 SO3, and H2O (by difference) 7.61, where the total is 100.00. The empirical formula calculated on the basis of (O,OH,H2O)22 is: Ca2.94Cu{1.93/2+} Al1.97Mg0.04Fe{0.02/2+} [(As3.74S0.16P0.12)Σ4.02O16.08](OH)3.87 · 2.05H2 O. The simplified formula is Ca3Cu2Al2(AsO4)4(OH)4 · 2H2O. Attikaite is orthorhombic, space group Pban, Pbam or Pba2; the unit-cell dimensions are a = 10.01(1), b = 8.199(5), c = 22.78(1) Å, V = 1870(3) Å3, and Z = 4. In the result of the ignition of attikaite for 30 to 35 min at 128 140°, the H2O bands in the IR spectrum disappear, while the OH-group band is not modified; the weight loss is 4.3%, which approximately corresponds to two H2O

  8. Retinoids and Retinal Diseases.

    PubMed

    Kiser, Philip D; Palczewski, Krzysztof

    2016-10-01

    Recent progress in molecular understanding of the retinoid cycle in mammalian retina stems from painstaking biochemical reconstitution studies supported by natural or engineered animal models with known genetic lesions and studies of humans with specific genetic blinding diseases. Structural and membrane biology have been used to detect critical retinal enzymes and proteins and their substrates and ligands, placing them in a cellular context. These studies have been supplemented by analytical chemistry methods that have identified small molecules by their spectral characteristics, often in conjunction with the evaluation of models of animal retinal disease. It is from this background that rational therapeutic interventions to correct genetic defects or environmental insults are identified. Thus, most presently accepted modulators of the retinoid cycle already have demonstrated promising results in animal models of retinal degeneration. These encouraging signs indicate that some human blinding diseases can be alleviated by pharmacological interventions.

  9. Retinoids and Retinal Diseases

    PubMed Central

    Kiser, Philip D.; Palczewski, Krzysztof

    2016-01-01

    Recent progress in molecular understanding of the retinoid cycle in mammalian retina stems from painstaking biochemical reconstitution studies supported by natural or engineered animal models with known genetic lesions and studies of humans with specific genetic blinding diseases. Structural and membrane biology have been used to detect critical retinal enzymes and proteins and their substrates and ligands, placing them in a cellular context. These studies have been supplemented by analytical chemistry methods that have identified small molecules by their spectral characteristics, often in conjunction with the evaluation of models of animal retinal disease. It is from this background that rational therapeutic interventions to correct genetic defects or environmental insults are identified. Thus, most presently accepted modulators of the retinoid cycle already have demonstrated promising results in animal models of retinal degeneration. These encouraging signs indicate that some human blinding diseases can be alleviated by pharmacological interventions. PMID:27917399

  10. Bioelectronic retinal prosthesis

    NASA Astrophysics Data System (ADS)

    Weiland, James D.

    2016-05-01

    Retinal prosthesis have been translated to clinical use over the past two decades. Currently, two devices have regulatory approval for the treatment of retinitis pigmentosa and one device is in clinical trials for treatment of age-related macular degeneration. These devices provide partial sight restoration and patients use this improved vision in their everyday lives to navigate and to detect large objects. However, significant vision restoration will require both better technology and improved understanding of the interaction between electrical stimulation and the retina. In particular, current retinal prostheses do not provide peripheral visions due to technical and surgical limitations, thus limiting the effectiveness of the treatment. This paper reviews recent results from human implant patients and presents technical approaches for peripheral vision.

  11. Oxidation of CO on a carbon-based material composed of nickel hydroxide and hydroxyl graphene oxide, (Ni4(OH)3-hGO)--a first-principles calculation.

    PubMed

    Yeh, Chen-Hao; Ho, Jia-Jen

    2015-03-21

    Nickel or nickel hydroxide clusters and graphene oxide (GO) composites are novel nanomaterials in the application of electrochemical catalysts. In this work, we calculated the energy of Ni4 adsorbed onto saturated hydroxyl graphene oxide (hGO), which forms a Ni4(OH)3 cluster on the hydroxyl graphene oxide (Ni4(OH)3-hGO) and releases 4.47 eV (5.22 eV with DFT-D3 correction). We subsequently studied the oxidation of CO on the Ni4(OH)3-hGO system via three mechanisms - LH, ER and carbonated mechanisms. Our results show that the activation energy for oxidation of the first CO molecule according to the ER mechanism is 0.14 eV (0.12 eV with DFT-D3 correction), much smaller than that with LH (Ea = 0.65 eV, 0.61 eV with DFT-D3 correction) and with carbonated (Ea = 1.28 eV, 1.20 eV with DFT-D3 correction) mechanisms. The barrier to oxidation of the second CO molecule to CO2 with the ER mechanism increases to 0.43 eV (0.37 eV with DFT-D3 correction), but still less than that via LH (Ea = 1.09 eV, 1.07 eV with DFT-D3 correction), indicating that CO could be effectively oxidized through the ER mechanism on the Ni4(OH)3/hGO catalyst.

  12. [Retinal pneumopexy in the treatment of rhegmatogenous retinal detachment].

    PubMed

    Levai, L; Gavriş, Monica; Gábor, Radó; Bagosi, P

    2014-01-01

    To evaluate the efficiency of retinal pneumopexy in patients with rhegmatogenous retinal detachment. This clinical prospective study unrolled between november 2010-june 2012 in the Ophthalmology Department of the Military Hospital in Cluj-Napoca and Satu Mare Emergency Hospital included 20 patients (20 eyes) with rhegmatogenous retinal detachment. Patients were treated with retinal pneumopexy followed by laser photocoagulation. Anatomical and functional results were evaluated 1, 3, 6, 12 and 19 months after treatment. In 17 eyes out of 20, we achieved retinal reattachment and visual recovery. Three cases yelded no success, these being further treated with posterior vitrectomy. Retinal pneumopexy is a minimally invasive treatment method of rhegmatogenous retinal detachment with very good results in well selected cases.

  13. Retinal Macroaneurysm Associated with Congenital Anomalous Retinal Artery.

    PubMed

    Kumar, Vinod; Agarwal, Rinky; Chandra, Parijat

    2017-07-01

    Retinal arteriolar macroaneurysms are a common cause of vision loss in elderly patients with hypertension and cardiovascular disease. Their occurrence in the young, however, is not well known. The purpose of this article is to describe an unusual cause of retinal arteriolar macroaneurysm in a healthy young man. A 30-year-old man presented with preretinal hemorrhage and macular exudation due to ruptured retinal artery macroaneurysm. The patient was treated with intravitreal bevacizumab and laser photocoagulation to the macroaneurysm. The exudation and preretinal hemorrhage resolved over several months. Fluorescein angiogram at this stage revealed a congenital anomalous retinal artery. Congenital anomalous retinal artery may be associated with retinal artery macroaneurysm even in the young age in the absence of any other predisposing factors. The presentation and treatment of such retinal artery macroaneurysm, however, may remain the same to those that occur in older patients.

  14. New vanadium tellurites: Syntheses, structures, optical properties of noncentrosymmetric VTeO{sub 4}(OH), centrosymmetric Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10})

    SciTech Connect

    Liang, Ming-Li; State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002; Marsh, Matthew

    2017-05-15

    Two new vanadium tellurites, VTeO{sub 4}(OH) (1) and Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10}) (2), have been synthesized successfully with the use of hydrothermal reactions. The crystal structures of the two compounds were determined by single-crystal X-ray diffraction. Compound 1 crystallizes in the polar space group Pca2{sub 1} (No. 29) while compound 2 crystallizes in the centrosymmetric space group C2/c (No. 15). The topography of compound 1 reveals a two-dimensional, layered structure comprised of VO{sub 6} octahedral chains and TeO{sub 3}(OH) zig-zag chains. Compound 2, on the contrary, features a three-dimensional [V{sub 4}O{sub 8}(Te{sub 3}O{sub 10})]{sup 4-} anionic framework withmore » Ba{sup 2+} ions filled into the 10-member ring helical tunnels. The [V{sub 4}O{sub 8}(Te{sub 3}O{sub 10})]{sup 4-} anionic network is the first 3D vanadium tellurite framework to be discovered in the alkaline-earth vanadium tellurite system. Powder second harmonic generation (SHG) measurements indicate that compound 1 shows a weak SHG response of about 0.3×KDP (KH{sub 2}PO{sub 4}) under 1064 nm laser radiation. Infrared spectroscopy, elemental analysis, thermal analysis, and dipole moment calculations have also been carried out. - Graphical abstract: VTeO{sub 4}(OH) (1) crystallizes in the noncentrosymmetric space group Pca2{sub 1} (No. 29) while Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10}) (2) crystallizes in the centrosymmetric space group C2/c (No. 15). - Highlights: • VTeO{sub 4}(OH) (1) and Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10}) (2) have been synthesized successfully with the use of hydrothermal reactions. • VTeO{sub 4}(OH) (1) crystallizes in the noncentrosymmetric space group Pca2{sub 1} and displays a weak SHG response. • VTeO{sub 4}(OH) (1) represents only the fourth SHG-active material found in vanadium tellurite systems. • Ba{sub 2}V{sub 4}O{sub 8}(Te{sub 3}O{sub 10}) (2) exhibits a novel three-dimensional [V{sub 4}O{sub 8}(Te{sub 3}O

  15. Nanomaterials and Retinal Toxicity

    EPA Science Inventory

    The neuroretina should be considered as a potential site of nanomaterial toxicity. Engineered nanomaterials may reach the retina through three potential routes of exposure including; intra­ vitreal injection of therapeutics; blood-borne delivery in the retinal vasculature an...

  16. Peripheral retinal degenerations and the risk of retinal detachment.

    PubMed

    Lewis, Hilel

    2003-07-01

    To review the degenerative diseases of the peripheral retina in relationship with the risk to develop a rhegmatogenous retinal detachment and to present recommendations for use in eyes at increased risk of developing a retinal detachment. Focused literature review and author's clinical experience. Retinal degenerations are common lesions involving the peripheral retina, and most of them are clinically insignificant. Lattice degeneration, degenerative retinoschisis, cystic retinal tufts, and, rarely, zonular traction tufts, can result in a rhegmatogenous retinal detachment. Therefore, these lesions have been considered for prophylactic therapy; however, adequate studies have not been performed to date. Well-designed, prospective, randomized clinical studies are necessary to determine the benefit-risk ratio of prophylactic treatment. In the meantime, the evidence available suggests that most of the peripheral retinal degenerations should not be treated except in rare, high-risk situations.

  17. Solid-state 2H NMR relaxation illuminates functional dynamics of retinal cofactor in membrane activation of rhodopsin

    PubMed Central

    Struts, Andrey V.; Salgado, Gilmar F. J.; Brown, Michael F.

    2011-01-01

    Rhodopsin is a canonical member of the family of G protein-coupled receptors, which transmit signals across cellular membranes and are linked to many drug interventions in humans. Here we show that solid-state 2H NMR relaxation allows investigation of light-induced changes in local ps–ns time scale motions of retinal bound to rhodopsin. Site-specific 2H labels were introduced into methyl groups of the retinal ligand that are essential to the activation process. We conducted solid-state 2H NMR relaxation (spin-lattice, T1Z, and quadrupolar-order, T1Q) experiments in the dark, Meta I, and Meta II states of the photoreceptor. Surprisingly, we find the retinylidene methyl groups exhibit site-specific differences in dynamics that change upon light excitation—even more striking, the C9-methyl group is a dynamical hotspot that corresponds to a crucial functional hotspot of rhodopsin. Following 11-cis to trans isomerization, the 2H NMR data suggest the β-ionone ring remains in its hydrophobic binding pocket in all three states of the protein. We propose a multiscale activation mechanism with a complex energy landscape, whereby the photonic energy is directed against the E2 loop by the C13-methyl group, and toward helices H3 and H5 by the C5-methyl of the β-ionone ring. Changes in retinal structure and dynamics initiate activating fluctuations of transmembrane helices H5 and H6 in the Meta I–Meta II equilibrium of rhodopsin. Our proposals challenge the Standard Model whereby a single light-activated receptor conformation yields the visual response—rather an ensemble of substates is present, due to the entropy gain produced by photolysis of the inhibitory retinal lock. PMID:21527723

  18. A semiempirical study of the optimized ground and excited state potential energy surfaces of retinal and its protonated Schiff base

    NASA Technical Reports Server (NTRS)

    Parusel, A. B.; Pohorille, A.

    2001-01-01

    The electronic ground and first excited states of retinal and its Schiff base are optimized for the first time using the semiempirical AM1 Hamiltonian. The barrier for rotation about the C(11)-C(12) double bond is characterized by variation of both the twist angle delta(C(10)-C(11)-C(12)-C(13)) and the bond length d(C(11)-C(12)). The potential energy surface is obtained by varying these two parameters. The calculated ground state rotational barrier is equal to 15.6 kcal/mol for retinal and 20.5 kcal/mol for its Schiff base. The all-trans conformation is more stable by 3.7 kcal/mol than the 11-cis geometry. For the first excited state, S(1,) the 90 degrees twisted geometry represents a saddle point for retinal with the rotational barrier of 14.6 kcal/mol. In contrast, this conformation is an energy minimum for the Schiff base. It can be easily reached at room temperature from the planar minima since it is separated from them by a barrier of only 0.6 kcal/mol. The 90 degrees minimum conformation is more stable than the all-trans by 8.6 kcal/mol. We are thus able to present a reaction path on the S(1) surface of the retinal Schiff base with an almost barrier-less geometrical relaxation into a twisted minimum geometry, as observed experimentally. The character of the ground and first excited singlet states underscores the need for the inclusion of double excitations in the calculations.

  19. Cytomegalovirus retinitis and FK 506.

    PubMed

    Ciardella, Antonio P; Barile, Gaetano; Langton, Kevin; Chang, Stanley

    2003-08-01

    To report a case of cytomegalovirus (CMV) retinitis in a patient immunosuppressed with FK 506. Interventional case report. Retrospective institutional study. One patient, diagnosed with bilateral CMV retinitis while on immunosuppressive treatment with FK 506, received systemic ganciclovir and intravitreal, slow-release ganciclovir implant in one eye, combined with reduction in FK 506 dose. Main outcome measures were visual acuity and regression of CMV retinitis. Visual acuity at presentation was 20/20 in the right eye and 20/50 in the left eye. During the 6 months of follow-up, there was no change in visual acuity in either eye. The areas of CMV retinitis demonstrated progressive regression, leaving diffuse retinal atrophy. Cytomegalovirus retinitis can be a sight-threatening complication of immunosuppressive treatment with FK 506. Ganciclovir treatment together with a reduction in FK 506 dose was effective in preserving vision.

  20. High altitude and retinal detachment.

    PubMed

    Morris, Daniel S; Severn, Philip S; Smith, Jonathan; Somner, John E A; Stannard, Kevin P; Cottrell, David G

    2007-01-01

    We describe the case of a 38-year-old man who presented with bilateral retinal detachments following a trek in Tibet during which time he took acetazolamide for prophylaxis of acute mountain sickness (AMS). This is the first time that retinal detachment has been described following a sojourn to high altitude. Acetazolamide has not been previously associated with retinal detachment when used for prophylaxis of AMS or indeed during its many ophthalmic applications. The patient made a good recovery following surgery, and we speculate that, although this could be coincidental and the patient did have risk factors for retinal detachment, the possibility of a causal link to high altitude should at least be entertained. We hypothesize that vitreous dehydration may have caused vitreoretinal traction and that hypobaric hypoxia may have changed the dynamic relationship between vitreous, retina, retinal pigment epithelium (RPE) and choroid, causing preexisting retinal holes to open, allowing subretinal fluid to accumulate and detach the retina.

  1. Small Animal Retinal Imaging

    NASA Astrophysics Data System (ADS)

    Choi, WooJhon; Drexler, Wolfgang; Fujimoto, James G.

    Developing and validating new techniques and methods for small animal imaging is an important research area because there are many small animal models of retinal diseases such as diabetic retinopathy, age-related macular degeneration, and glaucoma [1-6]. Because the retina is a multilayered structure with distinct abnormalities occurring in different intraretinal layers at different stages of disease progression, there is a need for imaging techniques that enable visualization of these layers individually at different time points. Although postmortem histology and ultrastructural analysis can be performed for investigating microscopic changes in the retina in small animal models, this requires sacrificing animals, which makes repeated assessment of the same animal at different time points impossible and increases the number of animals required. Furthermore, some retinal processes such as neurovascular coupling cannot be fully characterized postmortem.

  2. Inherited Retinal Degenerative Disease Registry

    ClinicalTrials.gov

    2017-09-13

    Eye Diseases Hereditary; Retinal Disease; Achromatopsia; Bardet-Biedl Syndrome; Bassen-Kornzweig Syndrome; Batten Disease; Best Disease; Choroidal Dystrophy; Choroideremia; Cone Dystrophy; Cone-Rod Dystrophy; Congenital Stationary Night Blindness; Enhanced S-Cone Syndrome; Fundus Albipunctatus; Goldmann-Favre Syndrome; Gyrate Atrophy; Juvenile Macular Degeneration; Kearns-Sayre Syndrome; Leber Congenital Amaurosis; Refsum Syndrome; Retinitis Pigmentosa; Retinitis Punctata Albescens; Retinoschisis; Rod-Cone Dystrophy; Rod Dystrophy; Rod Monochromacy; Stargardt Disease; Usher Syndrome

  3. Neuroprotection and Retinal Diseases.

    PubMed

    Paulus, Yannis M; Campbell, J Peter

    2016-01-01

    Neuronal death is the primary cause of vision loss in most retinal diseases. Neuroprotection is the modification of neurons, and/or their surrounding environment, to promote the survival and function of the neurons, especially in environments that would normally be deleterious to their health. Through advances in antioxidative therapy, neurotrophic support and anti-apoptotic therapy, the field of neuroprotection is advancing with the therapeutic hope of improving vision and clinical outcomes for patients. © 2016 S. Karger AG, Basel.

  4. Protecting retinal ganglion cells.

    PubMed

    Khatib, T Z; Martin, K R

    2017-02-01

    Retinal ganglion cell degeneration underlies several conditions which give rise to significant visual compromise, including glaucoma, hereditary optic neuropathies, ischaemic optic neuropathies, and demyelinating disease. In this review, we discuss the emerging strategies for neuroprotection specifically in the context of glaucoma, including pharmacological neuroprotection, mesenchymal stem cells, and gene therapy approaches. We highlight potential pitfalls that need to be considered when developing these strategies and outline future directions, including the prospects for clinical trials.

  5. The peripheral retinal 'map'.

    PubMed Central

    Williams, D. H.

    1975-01-01

    The condition of the periphery of the retinal field of the human eye is of considerable significance, it is suggested, to those participating in various sporting activities. Its boundaries shrink and expand depending upon the physiological conditions imposed both upon the eye and upon the organism as a whole. Consequently its message to the brain may be impaired under stress with resulting danger owing to delayed response. Images Fig. 3 Fig. 4 Fig. 5 PMID:1148574

  6. Glutamatergic Retinal Waves

    PubMed Central

    Kerschensteiner, Daniel

    2016-01-01

    Spontaneous activity patterns propagate through many parts of the developing nervous system and shape the wiring of emerging circuits. Prior to vision, waves of activity originating in the retina propagate through the lateral geniculate nucleus (LGN) of the thalamus to primary visual cortex (V1). Retinal waves have been shown to instruct the wiring of ganglion cell axons in LGN and of thalamocortical axons in V1 via correlation-based plasticity rules. Across species, retinal waves mature in three stereotypic stages (I–III), in which distinct circuit mechanisms give rise to unique activity patterns that serve specific functions in visual system refinement. Here, I review insights into the patterns, mechanisms, and functions of stage III retinal waves, which rely on glutamatergic signaling. As glutamatergic waves spread across the retina, neighboring ganglion cells with opposite light responses (ON vs. OFF) are activated sequentially. Recent studies identified lateral excitatory networks in the inner retina that generate and propagate glutamatergic waves, and vertical inhibitory networks that desynchronize the activity of ON and OFF cells in the wavefront. Stage III wave activity patterns may help segregate axons of ON and OFF ganglion cells in the LGN, and could contribute to the emergence of orientation selectivity in V1. PMID:27242446

  7. Update on retinal vascular caliber.

    PubMed

    Dumitrescu, Alina Gabriela; Voinea, Liliana; Badarau, Ioana Anca; Paun, Vanessa Andrada; Schowe, Marilena; Ciuluvica, Radu

    2017-01-01

    Retinal vessels are the only blood vessels that can be viewed directly, in vivo, repetitively and non-invasively. Retinal vessel caliber is influenced by physiological (age, sex, race, blood pressure, blood glucose, body mass index) and pathological (atherosclerosis, dyslipidemia, smoking) determinants. There are studies on large population groups that demonstrate the associations between retinal vasculature and subclinical or clinical changes in systemic diseases (hypertension, diabetes, stroke, renal or cardiac diseases). The assessment of retinal vessels can provide information about the pathophysiology of many diseases, but it also has a direct applicability in clinic, being used as a screening method that predicts the risk of their occurrence.

  8. Update on retinal vascular caliber

    PubMed Central

    Dumitrescu, Alina Gabriela; Voinea, Liliana; Badarau, Ioana Anca; Paun, Vanessa Andrada; Schowe, Marilena; Ciuluvica, Radu

    2017-01-01

    Retinal vessels are the only blood vessels that can be viewed directly, in vivo, repetitively and non-invasively. Retinal vessel caliber is influenced by physiological (age, sex, race, blood pressure, blood glucose, body mass index) and pathological (atherosclerosis, dyslipidemia, smoking) determinants. There are studies on large population groups that demonstrate the associations between retinal vasculature and subclinical or clinical changes in systemic diseases (hypertension, diabetes, stroke, renal or cardiac diseases). The assessment of retinal vessels can provide information about the pathophysiology of many diseases, but it also has a direct applicability in clinic, being used as a screening method that predicts the risk of their occurrence. PMID:29450394

  9. Mitochondrial Dysfunction in Retinal Diseases

    PubMed Central

    Barot, Megha; Gokulgandhi, Mitan R.; Mitra, Ashim K.

    2015-01-01

    The mitochondrion is a vital intracellular organelle for retinal cell function and survival. There is growing confirmation to support an association between mitochondrial dysfunction and a number of retinal degenerations. Investigations have also unveiled mitochondrial genomic instability as one of the contributing factors for age-related retinal pathophysiology. This review highlights the role of mitochondrial dysfunction originating from oxidative stress in the etiology of retinal diseases including diabetic retinopathy, glaucoma and age-related macular degeneration (AMD). Moreover, mitochondrial DNA (mtDNA) damage associated with AMD due to susceptibility of mtDNA to oxidative damage and failure of mtDNA repair pathways is also highlighted in this review. The susceptibility of neural retina and retinal pigment epithelium (RPE) mitochondria to oxidative damage with ageing appears to be a major factor in retinal degeneration. It thus appears that the mitochondrion is a weak link in the antioxidant defenses of retinal cells. In addition, failure of mtDNA repair pathways can also specifically contribute towards pathogenesis of AMD. This review will further summarize the prospective role of mitochondria targeting therapeutic agents for the treatment of retinal disease. Mitochondria based drug targeting to diminish oxidative stress or promote repair of mtDNA damage may offer potential alternatives for the treatment of various retinal degenerative diseases. PMID:21978133

  10. Mitochondrial dysfunction in retinal diseases.

    PubMed

    Barot, Megha; Gokulgandhi, Mitan R; Mitra, Ashim K

    2011-12-01

    The mitochondrion is a vital intracellular organelle for retinal cell function and survival. There is growing confirmation to support an association between mitochondrial dysfunction and a number of retinal degenerations. Investigations have also unveiled mitochondrial genomic instability as one of the contributing factors for age-related retinal pathophysiology. This review highlights the role of mitochondrial dysfunction originating from oxidative stress in the etiology of retinal diseases including diabetic retinopathy, glaucoma and age-related macular degeneration (AMD). Moreover, mitochondrial DNA (mtDNA) damage associated with AMD due to susceptibility of mtDNA to oxidative damage and failure of mtDNA repair pathways is also highlighted in this review. The susceptibility of neural retina and retinal pigment epithelium (RPE) mitochondria to oxidative damage with ageing appears to be a major factor in retinal degeneration. It thus appears that the mitochondrion is a weak link in the antioxidant defenses of retinal cells. In addition, failure of mtDNA repair pathways can also specifically contribute towards pathogenesis of AMD. This review will further summarize the prospective role of mitochondria targeting therapeutic agents for the treatment of retinal disease. Mitochondria based drug targeting to diminish oxidative stress or promote repair of mtDNA damage may offer potential alternatives for the treatment of various retinal degenerative diseases.

  11. Intraocular retinal prosthesis.

    PubMed Central

    Humayun, M S

    2001-01-01

    PURPOSE: An electronic implant that can bypass the damaged photoreceptors and electrically stimulate the remaining retinal neurons to restore useful vision has been proposed. A number of key questions remain to make this approach feasible. The goal of this thesis is to address the following 2 specific null hypotheses: (1) Stimulus parameters make no difference in the electrically elicited retinal responses. (2) Just as we have millions of photoreceptors, so it will take a device that can generate millions of pixels/light points to create useful vision. METHODS: For electrophysiologic experiments, 2 different setups were used. In the first setup, charge-balanced pulses were delivered to the retinal surface via electrodes inserted through an open sky approach in normal or blind retinal degenerate (rd) mice. In the second setup, the rabbit retina was removed under red light conditions from an enucleated eye and then maintained in a chamber while being superfused with oxygenated, heated Ames media. In both setups, stimulating electrodes and recording electrodes were positioned on the retinal surface to evaluate the effect of varying stimulation parameters on the orthodromic retinal responses (i.e., recording electrode placed between stimulating electrodes and optic nerve head). For psychophysical experiments, visual images were divided into pixels of light that could be projected in a pattern on the retina in up to 8 sighted volunteers. Subjects were asked to perform various tasks ranging from reading and face recognition to various activities of daily living. RESULTS: Electrophysiologic experiments: In a normal mouse, a single cycle of a 1-kHz sine wave was significantly more efficient than a 1-kHz square wave (P < .05), but no such difference was noted in either of the 8- or 16-week-old rd mouse groups (8-week-old, P = .426; 16-week-old, P = .078). Charge threshold was significantly higher in 16-week-old rd mouse versus both 8-week-old rd and normal mouse for every

  12. Rate constant calculations of the GeH4 + OH/OD → GeH3 + H2O/HOD reactions using an ab initio based full-dimensional potential energy surface.

    PubMed

    Espinosa-Garcia, J; Rangel, C; Corchado, J C

    2016-06-22

    We report an analytical full-dimensional potential energy surface for the GeH4 + OH → GeH3 + H2O reaction based on ab initio calculations. It is a practically barrierless reaction with very high exothermicity and the presence of intermediate complexes in the entrance and exit channels, reproducing the experimental evidence. Using this surface, thermal rate constants for the GeH4 + OH/OD isotopic reactions were calculated using two approaches: variational transition state theory (VTST) and quasi-classical trajectory (QCT) calculations, in the temperature range 200-1000 K, and results were compared with the only experimental data at 298 K. Both methods showed similar values over the whole temperature range, with differences less than 30%; and the experimental data was reproduced at 298 K, with negative temperature dependence below 300 K, which is associated with the presence of an intermediate complex in the entrance channel. However, while the QCT approach reproduced the experimental kinetic isotope effect, the VTST approach underestimated it. We suggest that this difference is associated with the harmonic approximation used in the treatment of vibrational frequencies.

  13. Two actinide-organic frameworks constructed by a tripodal flexible ligand: Occurrence of infinite {(UO2)O2(OH)3}4n and hexanuclear {Th6O4(OH)4} motifs

    NASA Astrophysics Data System (ADS)

    Liang, Lingling; Zhang, Ronglan; Zhao, Jianshe; Liu, Chiyang; Weng, Ng Seik

    2016-11-01

    Two new actinide metal-organic frameworks were constructed by using a tripodal flexible ligand tris (2-carboxyethyl) isocyanurate (H3tci) under hydrothermal condition. The combination of H3tci and uranyl nitrate hexahydrate in aqueous solution leads to the isolation of [(UO2)2(H2O)4]0.5(tci)2(UO2)4(OH)4·18H2O (1), which contains two distinct UO22+ coordination environments. Four uranyl cations, linked through μ3-OH respectively, result in the edge-sharing ribbons. Then, the layer structure is constructed by U-O clusters linked through other eight-coordinated uranyl unions, giving rise to a porous structure in the space. Topological analysis reveals that complex 1 belongs to a (4, 8)-connected net with a schläfli symbol of (34.26.3)2(34.46.56.68.73.8). Th3(tci)2O2(OH)2(H2O)3·12H2O (2) generated by the reaction of H3tci and thorium nitrate tetrahydrate, possesses nine-fold coodinated Th(IV) centers with a monocapped square antiprismatic geometry. The hexamers "Th6O4(OH)4" motifs are connected together by the carboxylate groups, showing a three-dimensional structures. Complex 2 takes on an 8-connected architecture and the point symbol is (424.64).

  14. Fabrication of Cubic Nanocages and Nanoframes by Dealloying Au/Ag Alloy Nanoboxes with an Aqueous Etchant Based on Fe(NO3)3 or NH4OH

    PubMed Central

    Lu, Xianmao; Au, Leslie; McLellan, Joseph; Li, Zhi-Yuan; Marquez, Manuel; Xia, Younan

    2008-01-01

    This paper describes a two-step procedure for generating cubic nanocages and nanoframes. In the first step, Au/Ag alloy nanoboxes were synthesized through the galvanic replacement reaction between Ag nanocubes and an aqueous HAuCl4 solution. The second step involved the selective removal (or dealloying) of Ag from the alloy nanoboxes with an aqueous etchant based on Fe(NO3)3 or NH4OH. The use of a wet etchant other than HAuCl4 for the dealloying process allows one to better control the wall thickness and porosity of resultant nanocages because there is no concurrent deposition of Au. By increasing the amount of Fe(NO3)3 or NH4OH added to the dealloying process, nanoboxes derived from 50-nm Ag nanocubes could be converted into nanocages and then cubic nanoframes with surface plasmon resonance (SPR) peaks continuously shifted from the visible region to 1200 nm. It is also possible to obtain nanocages with relatively narrow SPR peaks (with an FWHM as small as 180 nm) by controlling the amount of HAuCl4 used for the galvanic replacement reaction and thus optimization of the percentage of Au in the alloy nanoboxes. PMID:17489641

  15. Bi2(C2O4)3·7H2O and Bi(C2O4)OH Oxalates Thermal Decomposition Revisited. Formation of Nanoparticles with a Lower Melting Point than Bulk Bismuth.

    PubMed

    Roumanille, Pierre; Baco-Carles, Valérie; Bonningue, Corine; Gougeon, Michel; Duployer, Benjamin; Monfraix, Philippe; Le Trong, Hoa; Tailhades, Philippe

    2017-08-21

    Two bismuth oxalates, namely, Bi 2 (C 2 O 4 ) 3 ·7H 2 O and Bi(C 2 O 4 )OH, were studied in terms of synthesis, structural characterization, particle morphology, and thermal behavior under several atmospheres. The oxalate powders were produced by chemical precipitation from bismuth nitrate and oxalic acid solutions under controlled pH, then characterized by X-ray diffraction (XRD), temperature-dependent XRD, IR spectroscopy, scanning electron microscopy, and thermogravimetric differential thermal analyses. New results on the thermal decomposition of bismuth oxalates under inert or reducing atmospheres are provided. On heating in nitrogen, both studied compounds decompose into small bismuth particles. Thermal properties of the metallic products were investigated. The Bi(C 2 O 4 )OH decomposition leads to a Bi-Bi 2 O 3 metal-oxide composite product in which bismuth is confined in a nanometric size, due to surface oxidation. The melting point of such bismuth particles is strongly related to their crystallite size. The nanometric bismuth melting has thus been evidenced ∼40 °C lower than for bulk bismuth. These results should contribute to the development of the oxalate precursor route for low-temperature soldering applications.

  16. Central retinal artery occlusion - rethinking retinal survival time.

    PubMed

    Tobalem, Stephan; Schutz, James S; Chronopoulos, Argyrios

    2018-04-18

    The critical time from onset of complete occlusion of the central retinal artery (CRA) to functionally significant inner retinal infarction represents a window of opportunity for treatment and also has medical-legal implications, particularly when central retinal artery occlusion (CRAO) complicates therapeutic interventions. Here, we review the evidence for time to infarction from complete CRAO and discuss the implications of our findings. A Medline search was performed using each of the terms "central retinal artery occlusion", "retinal infarction", "retinal ischemia", and "cherry red spot" from 1970 to the present including articles in French and German. All retrieved references as well as their reference lists were screened for relevance. An Internet search using these terms was also performed to look for additional references. We find that the experimental evidence showing that inner retinal infarction occurs after 90-240 min of total CRAO, which is the interval generally accepted in the medical literature and practice guidelines, is flawed in important ways. Moreover, the retinal ganglion cells, supplied by the CRA, are part of the central nervous system which undergoes infarction after non-perfusion of 12-15 min or less. Retinal infarction is most likely to occur after only 12-15 min of complete CRAO. This helps to explain why therapeutic maneuvers for CRAO are often ineffective. Nevertheless, many CRAOs are incomplete and may benefit from therapy after longer intervals. To try to avoid retinal infarcton from inadvertent ocular compression by a headrest during prone anesthesia, the eyes should be checked at intervals of less than 15'.

  17. Perceptual Fading without Retinal Adaptation

    ERIC Educational Resources Information Center

    Hsieh, Po-Jang; Colas, Jaron T.

    2012-01-01

    A retinally stabilized object readily undergoes perceptual fading and disappears from consciousness. This startling phenomenon is commonly believed to arise from local bottom-up sensory adaptation to edge information that occurs early in the visual pathway, such as in the lateral geniculate nucleus of the thalamus or retinal ganglion cells. Here…

  18. Retinal Imaging and Image Analysis

    PubMed Central

    Abràmoff, Michael D.; Garvin, Mona K.; Sonka, Milan

    2011-01-01

    Many important eye diseases as well as systemic diseases manifest themselves in the retina. While a number of other anatomical structures contribute to the process of vision, this review focuses on retinal imaging and image analysis. Following a brief overview of the most prevalent causes of blindness in the industrialized world that includes age-related macular degeneration, diabetic retinopathy, and glaucoma, the review is devoted to retinal imaging and image analysis methods and their clinical implications. Methods for 2-D fundus imaging and techniques for 3-D optical coherence tomography (OCT) imaging are reviewed. Special attention is given to quantitative techniques for analysis of fundus photographs with a focus on clinically relevant assessment of retinal vasculature, identification of retinal lesions, assessment of optic nerve head (ONH) shape, building retinal atlases, and to automated methods for population screening for retinal diseases. A separate section is devoted to 3-D analysis of OCT images, describing methods for segmentation and analysis of retinal layers, retinal vasculature, and 2-D/3-D detection of symptomatic exudate-associated derangements, as well as to OCT-based analysis of ONH morphology and shape. Throughout the paper, aspects of image acquisition, image analysis, and clinical relevance are treated together considering their mutually interlinked relationships. PMID:22275207

  19. Retinal astrocytoma in a dog.

    PubMed

    Kuroki, Keiichi; Kice, Nathan; Ota-Kuroki, Juri

    2017-09-01

    A miniature schnauzer dog presenting with hyphema and glaucoma of the right eye had a retinal neoplasm. Neoplastic cells stained positively for glial fibrillary acidic protein, vimentin, and S-100 and largely negatively for oligodendrocyte transcription factor 2 by immunohistochemistry. The clinical and histopathological features of canine retinal astrocytomas are discussed.

  20. Multimodal Imaging in Retinal Vasculitis.

    PubMed

    Agarwal, Aniruddha; Afridi, Rubbia; Agrawal, Rupesh; Do, Diana V; Gupta, Vishali; Nguyen, Quan Dong

    2017-06-01

    Retinal vasculitis presents with inflammation involving the retinal vasculature as an isolated disease or in combination with other ocular or systemic conditions. This entity may be associated with a wide variety of clinical manifestations such as vascular sheathing, cotton-wool spots, retinal ischemia, and neovascularization. Often, retinal vasculitis and its complications lead to diagnostic challenges in identifying the exact etiology of the inflammation. Ancillary investigations such as fundus photography, fluorescein angiography, and more recently, adaptive optics imaging and optical coherence tomography angiography, may provide valuable information that help in establishing the exact diagnosis and initiation of appropriate therapy. In the index review, multimodal imaging features of retinal vasculitis are described. In addition, detection of vascular inflammation using novel noncontact imaging techniques has been highlighted.

  1. NinaB is essential for Drosophila vision but induces retinal degeneration in opsin-deficient photoreceptors.

    PubMed

    Voolstra, Olaf; Oberhauser, Vitus; Sumser, Emerich; Meyer, Nina E; Maguire, Michael E; Huber, Armin; von Lintig, Johannes

    2010-01-15

    In animals, visual pigments are essential for photoreceptor function and survival. These G-protein-coupled receptors consist of a protein moiety (opsin) and a covalently bound 11-cis-retinylidene chromophore. The chromophore is derived from dietary carotenoids by oxidative cleavage and trans-to-cis isomerization of double bonds. In vertebrates, the necessary chemical transformations are catalyzed by two distinct but structurally related enzymes, the carotenoid oxygenase beta-carotenoid-15,15'-monooxygenase and the retinoid isomerase RPE65 (retinal pigment epithelium protein of 65 kDa). Recently, we provided biochemical evidence that these reactions in insects are catalyzed by a single enzyme family member named NinaB. Here we show that in the fly pathway, carotenoids are mandatory precursors of the chromophore. After chromophore formation, the retinoid-binding protein Pinta acts downstream of NinaB and is required to supply photoreceptors with chromophore. Like ninaE encoding the opsin, ninaB expression is eye-dependent and is activated as a downstream target of the eyeless/pax6 and sine oculis master control genes for eye development. The requirement for coordinated synthesis of chromophore and opsin is evidenced by analysis of ninaE mutants. Retinal degeneration in opsin-deficient photoreceptors is caused by the chromophore and can be prevented by restricting its supply as seen in an opsin and chromophore-deficient double mutant. Thus, our study identifies NinaB as a key component for visual pigment production and provides evidence that chromophore in opsin-deficient photoreceptors can elicit retinal degeneration.

  2. Retinal Detachment Associated With Atopic Dermatitis.

    PubMed

    Kothari, Nikisha; Young, Ryan C; Read, Sarah P; Tutiven, Jacqueline; Perez, Victor L; Flynn, Harry W; Berrocal, Audina M

    2017-06-01

    Ocular manifestations related to atopic dermatitis include keratoconus, keratoconjunctivitis, cataract, and retinal detachment. The authors report three cases of retinal detachment associated with atopic dermatitis. Although the pathogenesis is poorly understood, chronic blunt trauma may play a role in the development of retinal detachment. In addition, retinal detachments associated with atopic dermatitis may have lower rates of successful retinal detachment repair. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:513-517.]. Copyright 2017, SLACK Incorporated.

  3. La lulzacite, Sr2Fe2+(Fe2+,Mg)2Al4(PO4)4(OH)10, un nouveau phosphate de strontium (Saint-Aubin-des-Châteaux, Loire-Atlantique, France)Lulzacite, Sr2Fe2+(Fe2+,Mg)2Al4(PO4)4(OH)10, a new strontium phosphate (Saint-Aubin-des-Châteaux, Loire-Atlantique, France).

    NASA Astrophysics Data System (ADS)

    Moëlo, Yves; Lasnier, Bernard; Palvadeau, Pierre; Léone, Philippe; Fontan, François

    2000-03-01

    Lulzacite, Sr 2Fe 2+(Fe 2+,Mg) 2Al 4(PO 4) 4(OH) 10, is a new mineral from Ordovician quartzites at Saint-Aubin-des-Châteaux (Loire-Atlantique, France). It occurs in veins of quartz and siderite, with pyrite, apatite and goyazite. Greyish-green colour; Mohs hardness: 5.5-6. Optically biaxial negative: nP = 1.654, nm = 1.674 and ng = 1.684. Distinctly pleochroic: brown-yellow to light blue-violet. Triclinic P1, a = 5.457(1), b = 9.131(2), c = 9.769(2) Å, α = 108.47(3)°, β = 91.72(3)°, γ = 97.44(3)°, V = 456.5(2) Å 3, Z = 1. Strongest X-ray diffraction lines ( d (Å), Iobs, hkl): 4.47 ( 41, 02 1), 3.591 ( 50, 111), 3.218 ( 100, 1 22), 3.132 ( 62, 120), 3.016 ( 56, 12 2), 2.878 ( 42, 03 2), 2.812 ( 62, 11 3), 2.653 ( 44, 1 32), 2.634 ( 43, 013). Dmes = 3.55, Dcalc = 3.58. Electron probe microanalysis (wt. %): SrO 21.79, BaO 1.20, FeO 16.13, MgO 2.97, Al 2O 3 19.16, P 2O 5 28.50, V 2O 5 0.64, H 2O (TGA) 10.29; total = 100.68 %. Structural formula (according to the crystal structure): (Sr 0.96Ba 0.04) 2Fe 2+(Fe 2+0.63Mg 0.37) 2Al 4[(P 0.98V 0.02)O 4] 4(OH) 10; ideally: Sr 2Fe 2+(Fe 2+,Mg) 2Al 4(PO 4) 4(OH) 10. Isotypic with jamesite (lead arsenate). Named in honour of Y. Lulzac, who discovered the species.

  4. Clinical Trials in Retinal Dystrophies.

    PubMed

    Grob, Seanna R; Finn, Avni; Papakostas, Thanos D; Eliott, Dean

    2016-01-01

    Research development is burgeoning for genetic and cellular therapy for retinal dystrophies. These dystrophies are the focus of many research efforts due to the unique biology and accessibility of the eye, the transformative advances in ocular imaging technology that allows for in vivo monitoring, and the potential benefit people would gain from success in the field - the gift of renewed sight. Progress in the field has revealed the immense complexity of retinal dystrophies and the challenges faced by researchers in the development of this technology. This study reviews the current trials and advancements in genetic and cellular therapy in the treatment of retinal dystrophies and also discusses the current and potential future challenges.

  5. Inner retinal oxygen extraction fraction in rat.

    PubMed

    Teng, Pang-yu; Wanek, Justin; Blair, Norman P; Shahidi, Mahnaz

    2013-01-21

    Oxygen extraction fraction (OEF), defined by the ratio of oxygen consumption to delivery, may be a useful parameter for assessing the retinal tissue status under impaired circulation. We report a method for measurement of inner retinal OEF in rats under normoxia and hypoxia based on vascular oxygen tension (PO(2)) imaging. Retinal vascular PO(2) measurements were obtained in 10 rats, using our previously developed optical section phosphorescence lifetime imaging system. Inner retinal OEF was derived from retinal vascular PO(2) measurements based on Fick's principle. Measurements of inner retinal OEF obtained under normoxia were compared between nasal and temporal retinal sectors and repeatability was determined. Inner retinal OEF measurements obtained under normoxia and hypoxia were compared. Retinal vascular PO(2) and inner retinal OEF measurements were repeatable (ICC ≥ 0.83). Inner retinal OEF measurements at nasal and temporal retinal sectors were correlated (R = 0.71; P = 0.02; n = 10). Under hypoxia, both retinal arterial and venous PO(2) decreased significantly as compared with normoxia (P < 0.001; n = 10). Inner retinal OEF was 0.46 ± 0.13 under normoxia and increased significantly to 0.67 ± 0.16 under hypoxia (mean ± SD; P < 0.001; n = 10). Inner retinal OEF is a promising quantitative biomarker for the adequacy of oxygen supply for metabolism under physiologically and pathologically altered conditions.

  6. Flexible retinal electrode array

    DOEpatents

    Okandan, Murat [Albuquerque, NM; Wessendorf, Kurt O [Albuquerque, NM; Christenson, Todd R [Albuquerque, NM

    2006-10-24

    An electrode array which has applications for neural stimulation and sensing. The electrode array can include a large number of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. The electrode array can be formed from a combination of bulk and surface micromachining, with electrode tips that can include an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis where the electrodes can be tailored to provide a uniform gentle contact pressure with optional sensing of this contact pressure at one or more of the electrodes.

  7. [New retinal imaging techniques].

    PubMed

    Gaudric, Alain

    2013-01-01

    Retinal imaging techniques progress rapidly. In many cases, the diagnosis of macular diseases can be done by the combination of fundus photography (color, monochromatic or autofluorescence images) and optical coherence tomography (OCT). Fluorescein or indocyanine green angiography remains useful when the other exams are not conclusive. Fundus angiography can be coupled with OCT. Other new investigation methods have appeared such as wide-field retinography on the one hand, or adaptive optics on the other hand which allows visualising photoreceptors in a very small field. Screening for diabetic retinopathy is based on color fundus photos. When the diagnostic of diabetic retinopathy is obvious, a more comprehensive fundus examination is warranted to decide on the treatment and follow-up.

  8. Microsystems Technology for Retinal Implants

    NASA Astrophysics Data System (ADS)

    Weiland, James

    2005-03-01

    The retinal prosthesis is targeted to treat age-related macular degeneration, retinitis pigmentosa, and other outer retinal degenerations. Simulations of artificial vision have predicted that 600-1000 individual pixels will be needed if a retinal prosthesis is to restore function such as reading large print and face recognition. An implantable device with this many electrode contacts will require microsystems technology as part of its design. An implantable retinal prosthesis will consist of several subsystems including an electrode array and hermetic packaging. Microsystems and microtechnology approaches are being investigated as possible solutions for these design problems. Flexible polydimethylsiloxane (PDMS) substrate electrode arrays and silicon micromachined electrode arrays are under development. Inactive PDMS electrodes have been implanted in 3 dogs to assess mechanical biocompatibility. 3 dogs were followed for 6 months. The implanted was securely fastened to the retina with a single retinal tack. No post-operative complications were evident. The array remained within 100 microns of the retinal surface. Histological evaluation showed a well preserved retina underneath the electrode array. A silicon device with electrodes suspended on micromachined springs has been implanted in 4 dogs (2 acute implants, 2 chronic implants). The device, though large, could be inserted into the eye and positioned on the retina. Histological analysis of the retina from the spring electrode implants showed that spring mounted posts penetrated the retina, thus the device will be redesigned to reduce the strength of the springs. These initial implants will provide information for the designers to make the next generation silicon device. We conclude that microsystems technology has the potential to make possible a retinal prosthesis with 1000 individual contacts in close proximity to the retina.

  9. The mechanics of retinal detachment

    NASA Astrophysics Data System (ADS)

    Chou, Tom; Siegel, Michael

    2013-03-01

    We present a model of the mechanical and fluid forces associated with exudative retinal detachments where the retinal photoreceptor cells separate typically from the underlying retinal pigment epithelium (RPE). By computing the total fluid volume flow arising from transretinal, vascular, and retinal pigment epithelium (RPE) pump currents, we determine the conditions under which the subretinal fluid pressure exceeds the maximum yield stress holding the retina and RPE together, giving rise to an irreversible, extended retinal delamination. We also investigate localized, blister-like retinal detachments by balancing mechanical tension in the retina with both the retina-RPE adhesion energy and the hydraulic pressure jump across the retina. For detachments induced by traction forces, we find a critical radius beyond which the blister is unstable to growth. Growth of a detached blister can also be driven by inflamed tissue within which e.g., the hydraulic conductivities of the retina or choroid increase, the RPE pumps fail, or the adhesion properties change. We determine the parameter regimes in which the blister either becomes unstable to growth, remains stable and finite-sized, or shrinks, allowing possible healing. This work supported by the Army Research Office through grant 58386MA

  10. Viscosity and retinal vein thrombosis.

    PubMed Central

    Ring, C P; Pearson, T C; Sanders, M D; Wetherley-Mein, G

    1976-01-01

    Whole-blood and plasma viscosity with haematological and biochemical investigations were measured in 44 patients with retinal vein occlusion. The patients were subdivided on the basis of fluorescein angiographic findings into: 1. Those with large areas of capillary non-perfusion. 2. Those with small areas of capillary non-perfusion. 3. Those with an intact capillary pattern. Capillary non-perfusion in retinal vein occlusion is associated with a higher morbidity owing to the complications of retinal neovascularization. Significantly higher values of whole-blood viscosity, packed cell volume, and yield stress have been found in patients with capillary non-perfusion than in those without. These differences may be of critical importance during the episode of retinal vein occlusion and suggest an aetiological factor in the development of capillary non-perfusion. Higher whole-blood and plasma viscosity values and plasma fibrinogen levels have also been shown in the whole retinal vein occlusion group compared with a control group of 30 individuals. These differences may be a factor in the development of retinal vein occlusion but their precise role is difficult to evaluate. Further biochemical investigations in the vein occlusion group supported the strong association with arterial disease and suggested a higher incidence of biochemical abnormalities in those patients with capillary non-perfusion. Images PMID:952813

  11. Retinal oxygen extraction in humans

    PubMed Central

    Werkmeister, René M.; Schmidl, Doreen; Aschinger, Gerold; Doblhoff-Dier, Veronika; Palkovits, Stefan; Wirth, Magdalena; Garhöfer, Gerhard; Linsenmeier, Robert A.; Leitgeb, Rainer A.; Schmetterer, Leopold

    2015-01-01

    Adequate function of the retina is dependent on proper oxygen supply. In humans, the inner retina is oxygenated via the retinal circulation. We present a method to calculate total retinal oxygen extraction based on measurement of total retinal blood flow using dual-beam bidirectional Doppler optical coherence tomography and measurement of oxygen saturation by spectrophotometry. These measurements were done on 8 healthy subjects while breathing ambient room air and 100% oxygen. Total retinal blood flow was 44.3 ± 9.0 μl/min during baseline and decreased to 18.7 ± 4.2 μl/min during 100% oxygen breathing (P < 0.001) resulting in a pronounced decrease in retinal oxygen extraction from 2.33 ± 0.51 μl(O2)/min to 0.88 ± 0.14 μl(O2)/min during breathing of 100% oxygen. The method presented in this paper may have significant potential to study oxygen metabolism in hypoxic retinal diseases such as diabetic retinopathy. PMID:26503332

  12. Retinal oxygen extraction in humans.

    PubMed

    Werkmeister, René M; Schmidl, Doreen; Aschinger, Gerold; Doblhoff-Dier, Veronika; Palkovits, Stefan; Wirth, Magdalena; Garhöfer, Gerhard; Linsenmeier, Robert A; Leitgeb, Rainer A; Schmetterer, Leopold

    2015-10-27

    Adequate function of the retina is dependent on proper oxygen supply. In humans, the inner retina is oxygenated via the retinal circulation. We present a method to calculate total retinal oxygen extraction based on measurement of total retinal blood flow using dual-beam bidirectional Doppler optical coherence tomography and measurement of oxygen saturation by spectrophotometry. These measurements were done on 8 healthy subjects while breathing ambient room air and 100% oxygen. Total retinal blood flow was 44.3 ± 9.0 μl/min during baseline and decreased to 18.7 ± 4.2 μl/min during 100% oxygen breathing (P < 0.001) resulting in a pronounced decrease in retinal oxygen extraction from 2.33 ± 0.51 μl(O2)/min to 0.88 ± 0.14 μl(O2)/min during breathing of 100% oxygen. The method presented in this paper may have significant potential to study oxygen metabolism in hypoxic retinal diseases such as diabetic retinopathy.

  13. Minireview: Fibronectin in retinal disease.

    PubMed

    Miller, Charles G; Budoff, Greg; Prenner, Jonathan L; Schwarzbauer, Jean E

    2017-01-01

    Retinal fibrosis, characterized by dysregulation of extracellular matrix (ECM) protein deposition by retinal endothelial cells, pigment epithelial cells, and other resident cell-types, is a unifying feature of several common retinal diseases. Fibronectin is an early constituent of newly deposited ECM and serves as a template for assembly of other ECM proteins, including collagens. Under physiologic conditions, fibronectin is found in all layers of Bruch's membrane. Proliferative vitreoretinopathy (PVR), a complication of retinal surgery, is characterized by ECM accumulation. Among the earliest histologic manifestations of diabetic retinopathy (DR) is capillary basement membrane thickening, which occurs due to perturbations in ECM homeostasis. Neovascularization, the hallmark of late stage DR as well as exudative age-related macular degeneration (AMD), involves ECM assembly as a scaffold for the aberrant new vessel architecture. Rodent models of retinal injury demonstrate a key role for fibronectin in complications characteristic of PVR, including retinal detachment. In mouse models of DR, reducing fibronectin gene expression has been shown to arrest the accumulation of ECM in the capillary basement membrane. Alterations in matrix metalloproteinase activity thought to be important in the pathogenesis of AMD impact the turnover of fibronectin matrix as well as collagens. Growth factors involved in PVR, AMD, and DR, such as PDGF and TGFβ, are known to stimulate fibronectin matrix assembly. A deeper understanding of how pathologic ECM deposition contributes to disease progression may help to identify novel targets for therapeutic intervention. © 2016 by the Society for Experimental Biology and Medicine.

  14. Retinal oxygen extraction in humans

    NASA Astrophysics Data System (ADS)

    Werkmeister, René M.; Schmidl, Doreen; Aschinger, Gerold; Doblhoff-Dier, Veronika; Palkovits, Stefan; Wirth, Magdalena; Garhöfer, Gerhard; Linsenmeier, Robert A.; Leitgeb, Rainer A.; Schmetterer, Leopold

    2015-10-01

    Adequate function of the retina is dependent on proper oxygen supply. In humans, the inner retina is oxygenated via the retinal circulation. We present a method to calculate total retinal oxygen extraction based on measurement of total retinal blood flow using dual-beam bidirectional Doppler optical coherence tomography and measurement of oxygen saturation by spectrophotometry. These measurements were done on 8 healthy subjects while breathing ambient room air and 100% oxygen. Total retinal blood flow was 44.3 ± 9.0 μl/min during baseline and decreased to 18.7 ± 4.2 μl/min during 100% oxygen breathing (P < 0.001) resulting in a pronounced decrease in retinal oxygen extraction from 2.33 ± 0.51 μl(O2)/min to 0.88 ± 0.14 μl(O2)/min during breathing of 100% oxygen. The method presented in this paper may have significant potential to study oxygen metabolism in hypoxic retinal diseases such as diabetic retinopathy.

  15. Minireview: Fibronectin in retinal disease

    PubMed Central

    Budoff, Greg; Prenner, Jonathan L; Schwarzbauer, Jean E

    2016-01-01

    Retinal fibrosis, characterized by dysregulation of extracellular matrix (ECM) protein deposition by retinal endothelial cells, pigment epithelial cells, and other resident cell-types, is a unifying feature of several common retinal diseases. Fibronectin is an early constituent of newly deposited ECM and serves as a template for assembly of other ECM proteins, including collagens. Under physiologic conditions, fibronectin is found in all layers of Bruch’s membrane. Proliferative vitreoretinopathy (PVR), a complication of retinal surgery, is characterized by ECM accumulation. Among the earliest histologic manifestations of diabetic retinopathy (DR) is capillary basement membrane thickening, which occurs due to perturbations in ECM homeostasis. Neovascularization, the hallmark of late stage DR as well as exudative age-related macular degeneration (AMD), involves ECM assembly as a scaffold for the aberrant new vessel architecture. Rodent models of retinal injury demonstrate a key role for fibronectin in complications characteristic of PVR, including retinal detachment. In mouse models of DR, reducing fibronectin gene expression has been shown to arrest the accumulation of ECM in the capillary basement membrane. Alterations in matrix metalloproteinase activity thought to be important in the pathogenesis of AMD impact the turnover of fibronectin matrix as well as collagens. Growth factors involved in PVR, AMD, and DR, such as PDGF and TGFβ, are known to stimulate fibronectin matrix assembly. A deeper understanding of how pathologic ECM deposition contributes to disease progression may help to identify novel targets for therapeutic intervention. PMID:27798121

  16. Filling in the retinal image

    NASA Technical Reports Server (NTRS)

    Larimer, James; Piantanida, Thomas

    1990-01-01

    The optics of the eye form an image on a surface at the back of the eyeball called the retina. The retina contains the photoreceptors that sample the image and convert it into a neural signal. The spacing of the photoreceptors in the retina is not uniform and varies with retinal locus. The central retinal field, called the macula, is densely packed with photoreceptors. The packing density falls off rapidly as a function of retinal eccentricity with respect to the macular region and there are regions in which there are no photoreceptors at all. The retinal regions without photoreceptors are called blind spots or scotomas. The neural transformations which convert retinal image signals into percepts fills in the gaps and regularizes the inhomogeneities of the retinal photoreceptor sampling mosaic. The filling-in mechamism plays an important role in understanding visual performance. The filling-in mechanism is not well understood. A systematic collaborative research program at the Ames Research Center and SRI in Menlo Park, California, was designed to explore this mechanism. It was shown that the perceived fields which are in fact different from the image on the retina due to filling-in, control some aspects of performance and not others. Researchers have linked these mechanisms to putative mechanisms of color coding and color constancy.

  17. Ruptured retinal arterial macroaneurysm: diagnosis and management.

    PubMed

    Speilburg, Ashley M; Klemencic, Stephanie A

    2014-01-01

    Retinal arterial macroaneurysm is an acquired, focal dilation of a retinal artery, typically occurring within the first three bifurcations of the central retinal artery. The clinical presentation of a retinal arterial macroaneurysm is highly variable, making initial diagnosis difficult and differentials many. Identification of retinal arterial macroaneurysms is crucial to appropriately co-manage with the primary care physician for hypertension control. Prognosis is generally good and observation is often an adequate treatment. However, in cases of macular threat or involvement, some treatment options are available and referral to a retinal specialist is indicated. Copyright © 2013 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

  18. Retinal pigmentary changes in chronic uveitis mimicking retinitis pigmentosa.

    PubMed

    Sevgi, D Damla; Davoudi, Samaneh; Comander, Jason; Sobrin, Lucia

    2017-09-01

    To present retinal pigmentary changes mimicking retinitis pigmentosa (RP) as a finding of advanced uveitis. We retrospectively reviewed charts of patients without a family history of inherited retinal degenerations who presented with retinal pigment changes and signs of past or present intraocular inflammation. Comprehensive eye examination including best-corrected visual acuity, slit-lamp examination and dilated fundus examination was performed on all patients in addition to color fundus photography, optical coherence tomography, fluorescein angiography (FA), and full-field electroretinogram testing. We identified five patients with ages ranging from 33 to 66 years, who presented with RP-like retinal pigmentary changes which were eventually attributed to longstanding uveitis. The changes were bilateral in three cases and unilateral in two cases. Four of five cases presented with active inflammation, and the remaining case showed evidence of active intraocular inflammation during follow-up. This study highlights the overlapping features of advanced uveitis and RP including the extensive pigmentary changes. Careful review of possible past uveitis history, detailed examination of signs of past or present inflammation and ancillary testing, with FA often being most helpful, are required for the correct diagnosis. This is important, because intervention can prevent further damage if the cause of the pigmentary changes is destructive inflammation.

  19. Spectrophotometric retinal oximetry in pigs.

    PubMed

    Traustason, Sindri; Kiilgaard, Jens F; Karlsson, Robert A; Hardarson, Sveinn H; Stefansson, Einar; la Cour, Morten

    2013-04-17

    To assess the validity of spectrophotometric retinal oximetry by comparison to blood gas analysis and intravitreal measurements of partial pressure of oxygen (pO(2)). Female domestic pigs were used for all experiments (n = 8). Oxygen fraction in inspired air was changed using a mixture of room air, pure oxygen, and pure nitrogen, ranging from 5% to 100% oxygen. Femoral arterial blood gas analysis and retinal oximetry were performed at each level of inspiratory oxygen fraction. Retinal oximetry was performed using a commercial instrument, the Oxymap Retinal Oximeter T1. The device simultaneously acquires images at two wavelengths (570 nm and 600 nm), and specialized software automatically detects retinal blood vessels. In three pigs, invasive pO(2) measurements were performed after the initial noninvasive measurements. Comparison of femoral arterial oxygen saturation and the optical density ratio over retinal arteries revealed an approximately linear relationship (R(2) = 0.74, P = 3.4 × 10(-9)). In order to test the validity of applying the arterial calibration to veins, we compared noninvasive oximetry measurements to invasive pO2 measurements in three pigs. This relationship was approximately linear (R(2) = 0.45, P = 0.04). Noninvasive spectrophotometric oximetry is sensitive to changes in oxygen saturation in pigs and correlated with intravitreal pO(2) measurements and with femoral artery pO(2). Pigs present a higher intraindividual variability in retinal oxygen saturation and a lower overall saturation than do humans. The difference between porcine and human eyes makes direct comparisons of measurements difficult.

  20. Retinal AO OCT

    NASA Astrophysics Data System (ADS)

    Zawadzki, Robert J.; Miller, Donald T.

    The last two decades have witnessed extraordinary advances in optical technology to image noninvasively and at high resolution the posterior segment of the eye. Two of the most impactful technological advancements over this period have arguably been optical coherence tomography (OCT) and adaptive optics (AO). The strengths of these technologies complement each other and when combined have been shown to provide unprecedented, micron-scale resolution (<3 μm) in all three dimensions and sensitivity to image the cellular retina in the living eye. This powerful extension of OCT, that is AO-OCT, is the focus of this chapter. It presents key aspects of designing and implementing AO-OCT systems. Particular attention is devoted to the relevant optical properties of the eye that ultimately define these systems, AO componentry and operation tailored for ophthalmic use, and of course use of the latest technologies and methods in OCT for ocular imaging. It surveys the wide range of AO-OCT designs that have been developed for retinal imaging, with AO integrated into every major OCT design configuration. Finally, it reviews the scientific and clinical studies reported to date that show the exciting potential of AO-OCT to image the microscopic retina and fundus in ways not previously possible with other noninvasive methods and a look to future developments in this rapidly growing field.

  1. 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.

  2. Morphometric analyses of retinal sections.

    PubMed

    Chan, Tin Fung; Chiu, Kin; Lok, Carmen Ka Ming; Lau, Ho Wing; So, Kwok-Fai; Chang, Raymond Chuen-Chung

    2012-02-19

    Morphometric analyses of retinal sections have been used in examining retinal diseases. For examples, neuronal cells were significantly lost in the retinal ganglion cell layer (RGCL) in rat models with N-methyl-D-aspartate (NMDA)-induced excitotoxicity(1), retinal ischemia-reperfusion injury(2) and glaucoma(3). Reduction of INL and inner plexiform layer (IPL) thicknesses were reversed with citicoline treatment in rats' eyes subjected to kainic acid-mediated glutamate excitotoxicity(4). Alteration of RGC density and soma sizes were observed with different drug treatments in eyes with elevated intraocular pressure(3,5,6). Therefore, having objective methods of analyzing the retinal morphometries may be of great significance in evaluating retinal pathologies and the effectiveness of therapeutic strategies. The retinal structure is multi-layers and several different kinds of neurons exist in the retina. The morphometric parameters of retina such as cell number, cell size and thickness of different layers are more complex than the cell culture system. Early on, these parameters can be detected using other commercial imaging software. The values are normally of relative value, and changing to the precise value may need further accurate calculation. Also, the tracing of the cell size and morphology may not be accurate and sensitive enough for statistic analysis, especially in the chronic glaucoma model. The measurements used in this protocol provided a more precise and easy way. And the absolute length of the line and size of the cell can be reported directly and easy to be copied to other files. For example, we traced the margin of the inner and outer most nuclei in the INL and formed a line then using the software to draw a 90 degree angle to measure the thickness. While without the help of the software, the line maybe oblique and the changing of retinal thickness may not be repeatable among individual observers. In addition, the number and density of RGCs can also be

  3. Communication: Analytical optimal pulse shapes obtained with the aid of genetic algorithms: Controlling the photoisomerization yield of retinal

    SciTech Connect

    Guerrero, R. D., E-mail: rdguerrerom@unal.edu.co; Arango, C. A., E-mail: caarango@icesi.edu.co; Reyes, A., E-mail: areyesv@unal.edu.co

    2016-07-21

    We recently proposed a Quantum Optimal Control (QOC) method constrained to build pulses from analytical pulse shapes [R. D. Guerrero et al., J. Chem. Phys. 143(12), 124108 (2015)]. This approach was applied to control the dissociation channel yields of the diatomic molecule KH, considering three potential energy curves and one degree of freedom. In this work, we utilized this methodology to study the strong field control of the cis-trans photoisomerization of 11-cis retinal. This more complex system was modeled with a Hamiltonian comprising two potential energy surfaces and two degrees of freedom. The resulting optimal pulse, made of 6 linearlymore » chirped pulses, was capable of controlling the population of the trans isomer on the ground electronic surface for nearly 200 fs. The simplicity of the pulse generated with our QOC approach offers two clear advantages: a direct analysis of the sequence of events occurring during the driven dynamics, and its reproducibility in the laboratory with current laser technologies.« less

  4. Neuroglobin Protection in Retinal Ischemia

    PubMed Central

    Chan, Anita S.Y.; Saraswathy, Sindhu; Rehak, Matus; Ueki, Mari

    2012-01-01

    Purpose. Neuroglobin (Ngb) is a vertebrate globin that is predominantly expressed in the retina and brain. To explore the role of Ngb in retinal neuroprotection during ischemia reperfusion (IR), the authors examined the effect of Ngb overexpression in the retina in vivo by using Ngb-transgenic (Ngb-Tg) mice. Methods. Retinal IR was induced in Ngb overexpressing Ngb-Tg mice and wild type (WT) mice by cannulating the anterior chamber and transiently elevating the IOP for 60 minutes. After Day 7 of reperfusion, the authors evaluated Ngb mRNA and protein expression in nonischemic control as well as ischemic mice and its effect on retinal histology, mitochondrial oxidative stress, and apoptosis, using morphometry and immunohistochemistry, quantitative PCR analysis and Western blot techniques. Results. Ngb-Tg mice without ischemia overexpress Ngb mRNA 11.3-fold (SE ± 0.457, P < 0.05) higher than WT control mice, and this overexpression of Ngb protein was localized to the mitochondria of the ganglion cells, outer and inner plexiform layers, and photoreceptor inner segments. This overexpression of Ngb is associated with decreased mitochondrial DNA damage in Ngb-Tg mice with IR in comparison with WT. Ngb-Tg mice with IR also revealed significant preservation of retinal thickness, significantly less activated caspase 3 protein expression, and apoptosis in comparison with WT mice. Conclusions. Neuroglobin overexpression plays a neuroprotective role against retinal ischemia reperfusion injury due to decreasing of mitochondrial oxidative stress-mediated apoptosis. PMID:22167093

  5. Spatial alignment over retinal scotomas.

    PubMed

    Crossland, Michael D; Bex, Peter J

    2009-03-01

    Perceptual completion can mask the presence of physiological and pathologic retinal scotomas. This psychophysical study used a spatial alignment task to examine the processes underlying this perceptual completion. Similarities between the completion of pathologic and physiological scotomas would be consistent with large-scale reorganization of the visual system in eye disease In five control subjects with no eye disease, Vernier alignment thresholds were measured over the physiological blind spot at the optic nerve head and over equally eccentric temporal retina. For nine subjects with retinal scotomas, alignment thresholds were measured over the maximum vertical extent of the larger scotoma in one eye and at an equal separation and eccentricity in the eye with a smaller or no scotoma In control subjects, alignment thresholds were better over the physiological blind spot than over equally eccentric temporal retina (P < 0.05). Alignment thresholds were no better over pathologic retinal scotomas than more intact, equally eccentric retina (P = 0.9) These quantitative differences implicate different mechanisms for perceptual completion over pathologic and physiological retinal scotomas. Filling in across pathologic scotomas appears to involve higher level image processing-based mechanisms that operate even when their input is interrupted. Filling-in at the optic nerve head involves additional low-level processes that may be hardwired, in which receptive fields span the blind spot and support fine orientation discriminations. These results argue against low-level reorganization of the visual system in people with retinal disease.

  6. Spatial Alignment over Retinal Scotomas

    PubMed Central

    Crossland, Michael D.; Bex, Peter J.

    2013-01-01

    Purpose Perceptual completion can mask the presence of physiological and pathologic retinal scotomas. This psychophysical study used a spatial alignment task to examine the processes underlying this perceptual completion. Similarities between the completion of pathologic and physiological scotomas would be consistent with large-scale reorganization of the visual system in eye disease Methods In five control subjects with no eye disease, Vernier alignment thresholds were measured over the physiological blind spot at the optic nerve head and over equally eccentric temporal retina. For nine subjects with retinal scotomas, alignment thresholds were measured over the maximum vertical extent of the larger scotoma in one eye and at an equal separation and eccentricity in the eye with a smaller or no scotoma Results In control subjects, alignment thresholds were better over the physiological blind spot than over equally eccentric temporal retina (P < 0.05). Alignment thresholds were no better over pathologic retinal scotomas than more intact, equally eccentric retina (P = 0.9) Conclusions These quantitative differences implicate different mechanisms for perceptual completion over pathologic and physiological retinal scotomas. Filling in across pathologic scotomas appears to involve higher level image processing-based mechanisms that operate even when their input is interrupted. Filling-in at the optic nerve head involves additional low-level processes that may be hardwired, in which receptive fields span the blind spot and support fine orientation discriminations. These results argue against low-level reorganization of the visual system in people with retinal disease. PMID:19029023

  7. Near infrared autofluorescence imaging of retinal diseases.

    PubMed

    Skondra, Dimitra; Papakostas, Thanos D; Hunter, Rebecca; Vavvas, Demetrios G

    2012-01-01

    Near infrared autofluorescence (excitation 787 nm, emission >800 nm) is a non-invasive imaging technology that provides information on the distribution of melanin within the retinal pigment epithelial cell/choroid complex. This review contains an introduction to near infrared autofluorescence imaging methods. Characteristics of near infrared imaging in a variety of retinal diseases, including age-related macular degeneration, choroidal nevus, retinal degenerations, retinal dystrophies, central serous chorioretinopathy, pseudoxanthoma elasticum and chloroquine retinopathy, are summarized.

  8. Inherited Retinal Degenerative Disease Clinical Trial Network

    DTIC Science & Technology

    2012-10-01

    the total number of individuals affected by retinitis pigmentosa (RP) and other forms of rare inherited retinal degenerative diseases is estimated at...for autosomal dominant retinitis pigmentosa ). As new interventions become available for clinical evaluation, the creation of such a network will...dominant retinitis pigmentosa at six sites- the CTEC site at University of Utah and five recruitment sites- the Retina Foundation of the Southwest

  9. Infrared and Raman spectroscopic characterizations on new Fe sulphoarsenate hilarionite (Fe2(III)(SO4)(AsO4)(OH)·6H2O): Implications for arsenic mineralogy in supergene environment of mine area

    NASA Astrophysics Data System (ADS)

    Liu, Jing; He, LiLe; Dong, Faqin; Frost, Ray L.

    2017-01-01

    Hilarionite (Fe2 (SO4)(AsO4)(OH)·6H2O) is a new Fe sulphoarsenates mineral, which recently is found in the famous Lavrion ore district, Atliki Prefecture, Greece. The spectroscopic study of hilarionite enriches the data of arsenic mineralogy in supergene environment of a mine area. The infrared and Raman means are used to characterize the molecular structure of this mineral. The IR bands at 875 and 905 cm- 1 are assigned to the antisymmetric stretching vibrations of AsO43 -. The IR bands at 1021, 1086 and 1136 cm- 1 correspond to the possible antisymmetric and symmetric stretching vibrations of SO42 -. The Raman bands at 807, 843 and 875 cm- 1 clearly show that arsenate components in the mineral structure, which are assigned to the symmetric stretching vibrations (ν1) of AsO43 - (807 and 843 cm- 1) and the antisymmetric vibration (ν3) (875 cm- 1). IR bands provide more sulfate information than Raman, which can be used as the basis to distinguish hilarionite from kaňkite. The powder XRD data shows that hilarionite has obvious differences with the mineral structure of kaňkite. The thermoanalysis and SEM-EDX results show that hilarionite has more sulfate than arsenate.

  10. Infrared and Raman spectroscopic characterization of the silicate-carbonate mineral carletonite - KNa4Ca4Si8O18(CO3)4(OH,F)·H2O

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Xi, Yunfei; Scholz, Ricardo; López, Andrés; Belotti, Fernanda Maria

    2013-06-01

    An assessment of the molecular structure of carletonite a rare phyllosilicate mineral with general chemical formula given as KNa4Ca4Si8O18(CO3)4(OH,F)·H2O has been undertaken using vibrational spectroscopy. Carletonite has a complex layered structure. Within one period of c, it contains a silicate layer of composition NaKSi8O18·H2O, a carbonate layer of composition NaCO3·0.5H2O and two carbonate layers of composition NaCa2CO3(F,OH)0.5. Raman bands are observed at 1066, 1075 and 1086 cm-1. Whether these bands are due to the CO32- ν1 symmetric stretching mode or to an SiO stretching vibration is open to question. Multiple bands are observed in the 300-800 cm-1 spectral region, making the attribution of these bands difficult. Multiple water stretching and bending modes are observed showing that there is much variation in hydrogen bonding between water and the silicate and carbonate surfaces.

  11. Ultrasensitive peroxynitrite-based luminescence with L-012 as a screening system for antioxidative/antinitrating substances, e.g. Tylenol (acetaminophen), 4-OH tempol, quercetin and carboxy-PTIO.

    PubMed

    Van Dyke, Knox; Ghareeb, Erica; Van Dyke, Mark; Van Thiel, David H

    2007-01-01

    Previously our group developed a water-soluble antioxidant screening system using the luminescence of the reaction of peroxynitrite and luminol. In the present study we replaced luminol with the luminol-like compound L-012. This increases the production of luminescence approximately 100-fold and therefore, with a higher signal:noise ratio, this new system can detect antioxidation and antinitration effects at lower doses of the inhibitor. We studied acetaminophen (Tylenol) and its metabolite 3-nitroacetaminophen, tyrosine and nitrotyrosine and all these substances were inhibitory in a dose-responsive manner and below micromolar amounts. In addition quercetin, a polyphenol, was highly active (below micromolar amounts) as an antioxidant and antinitrating compound. 4-OH tempol, the stable free radical, superoxide dismutase (SOD) mimetic, was inhibitory in a dose-responsive manner and below micromolar amounts. Carboxy-PTIO was inhibitory at 10 times micromolar amount but not below that dose, which may be related to colour quenching, since the drug is deeply blue, or possibly it is an inhibitor with a slow kinetic profile. Finally, the amino acid tyrosine has been found to be inhibitory in micromolar amounts, similar to acetaminophen. This indicates that tyrosine can act as an antioxidant and antinitration target alone or conjugated in protein, e.g. insulin. (c) 2007 John Wiley & Sons, Ltd.

  12. Photovoltaic Retinal Prosthesis for Restoring Sight to Patients Blinded by Retinal Injury or Degeneration

    DTIC Science & Technology

    2016-02-01

    and various motor prostheses [6][7][8] are constantly improving. Degenerative retinal diseases, such as retinitis pigmentosa and age related macular...AD_______________ Award Number: W81XWH-15-1-0009 TITLE: Photovoltaic Retinal Prosthesis for Restoring Sight to Patients Blinded by Retinal ...DATES COVERED 1 Feb 2015 - 31 Jan 2016 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Photovoltaic Retinal Prosthesis for Restoring Sight to Patients

  13. Transcorneal Electrical Stimulation Therapy for Retinal Disease

    ClinicalTrials.gov

    2012-05-03

    Retinitis Pigmentosa; Macula Off; Primary Open Angle Glaucoma; Hereditary Macular Degeneration; Treated Retina Detachment; Retinal Artery Occlusion; Retinal Vein Occlusion; Non-Arthritic-Anterior-Ischemic Optic-Neuropathy; Hereditary Autosomal Dominant Optic Atrophy; Dry Age Related Macular Degeneration; Ischemic Macula Edema

  14. Inherited Retinal Degenerative Clinical Trial Network

    DTIC Science & Technology

    2009-10-01

    ending in blindness. In the United States, the total number of individuals affected by retinitis pigmentosa (RP) and other forms of rare inherited...AD_________________ AWARD NUMBER: W81XWH-07-1-0720 TITLE: Inherited Retinal Degenerative...Final 3. DATES COVERED 27 Sep 2007 – 29 Sep 2009 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Inherited Retinal Degenerative Clinical Trial Network

  15. Diabetes and Retinal Vascular Dysfunction

    PubMed Central

    Shin, Eui Seok; Sorenson, Christine M.; Sheibani, Nader

    2014-01-01

    Diabetes predominantly affects the microvascular circulation of the retina resulting in a range of structural changes unique to this tissue. These changes ultimately lead to altered permeability, hyperproliferation of endothelial cells and edema, and abnormal vascularization of the retina with resulting loss of vision. Enhanced production of inflammatory mediators and oxidative stress are primary insults with significant contribution to the pathogenesis of diabetic retinopathy (DR). We have determined the identity of the retinal vascular cells affected by hyperglycemia, and have delineated the cell autonomous impact of high glucose on function of these cells. We discuss some of the high glucose specific changes in retinal vascular cells and their contribution to retinal vascular dysfunction. This knowledge provides novel insight into the molecular and cellular defects contributing to the development and progression of diabetic retinopathy, and will aid in the development of innovative, as well as target specific therapeutic approaches for prevention and treatment of DR. PMID:25667739

  16. Exploring the retinal connectome

    PubMed Central

    Anderson, James R.; Jones, Bryan W.; Watt, Carl B.; Shaw, Margaret V.; Yang, Jia-Hui; DeMill, David; Lauritzen, James S.; Lin, Yanhua; Rapp, Kevin D.; Mastronarde, David; Koshevoy, Pavel; Grimm, Bradley; Tasdizen, Tolga; Whitaker, Ross

    2011-01-01

    Purpose A connectome is a comprehensive description of synaptic connectivity for a neural domain. Our goal was to produce a connectome data set for the inner plexiform layer of the mammalian retina. This paper describes our first retinal connectome, validates the method, and provides key initial findings. Methods We acquired and assembled a 16.5 terabyte connectome data set RC1 for the rabbit retina at ≈2 nm resolution using automated transmission electron microscope imaging, automated mosaicking, and automated volume registration. RC1 represents a column of tissue 0.25 mm in diameter, spanning the inner nuclear, inner plexiform, and ganglion cell layers. To enhance ultrastructural tracing, we included molecular markers for 4-aminobutyrate (GABA), glutamate, glycine, taurine, glutamine, and the in vivo activity marker, 1-amino-4-guanidobutane. This enabled us to distinguish GABAergic and glycinergic amacrine cells; to identify ON bipolar cells coupled to glycinergic cells; and to discriminate different kinds of bipolar, amacrine, and ganglion cells based on their molecular signatures and activity. The data set was explored and annotated with Viking, our multiuser navigation tool. Annotations were exported to additional applications to render cells, visualize network graphs, and query the database. Results Exploration of RC1 showed that the 2 nm resolution readily recapitulated well known connections and revealed several new features of retinal organization: (1) The well known AII amacrine cell pathway displayed more complexity than previously reported, with no less than 17 distinct signaling modes, including ribbon synapse inputs from OFF bipolar cells, wide-field ON cone bipolar cells and rod bipolar cells, and extensive input from cone-pathway amacrine cells. (2) The axons of most cone bipolar cells formed a distinct signal integration compartment, with ON cone bipolar cell axonal synapses targeting diverse cell types. Both ON and OFF bipolar cells receive

  17. Retinal Optical Coherence Tomography Imaging

    NASA Astrophysics Data System (ADS)

    Drexler, Wolfgang; Fujimoto, James G.

    The eye is essentially transparent, transmitting light with only minimal optical attenuation and scattering providing easy optical access to the anterior segment as well as the retina. For this reason, ophthalmic and especially retinal imaging has been not only the first but also most successful clinical application for optical coherence tomography (OCT). This chapter focuses on the development of OCT technology for retinal imaging. OCT has significantly improved the potential for early diagnosis, understanding of retinal disease pathogenesis, as well as monitoring disease progression and response to therapy. Development of ultrabroad bandwidth light sources and high-speed detection techniques has enabled significant improvements in ophthalmic OCT imaging performance, demonstrating the potential of three-dimensional, ultrahigh-resolution OCT (UHR OCT) to perform noninvasive optical biopsy of the living human retina, i.e., the in vivo visualization of microstructural, intraretinal morphology in situ approaching the resolution of conventional histopathology. Significant improvements in axial resolution and speed not only enable three-dimensional rendering of retinal volumes but also high-definition, two-dimensional tomograms, topographic thickness maps of all major intraretinal layers, as well as volumetric quantification of pathologic intraretinal changes. These advances in OCT technology have also been successfully applied in several animal models of retinal pathologies. The development of light sources emitting at alternative wavelengths, e.g., around #1,060 nm, not only enabled three-dimensional OCT imaging with enhanced choroidal visualization but also improved OCT performance in cataract patients due to reduced scattering losses in this wavelength region. Adaptive optics using deformable mirror technology, with unique high stroke to correct higher-order ocular aberrations, with specially designed optics to compensate chromatic aberration of the human eye, in

  18. Retinal detachment surgery at Nepal Eye Hospital.

    PubMed

    Malla, O K; Shrestha, S; Shrestha, S P; Byanju, R N; Karki, D B

    2009-01-01

    Retinal diseases are one of the important causes of blindness in Nepal. This study is done with objectives of finding the outcome of retinal detachment surgery. A retrospective analysis of 110 patients who underwent retinal detachment surgery over five year period was conducted in Nepal. Retinal re-attachment was achieved in 94.4% and postoperative visual acuity of 6/36 to 6/6 was achieved in 52.7% (As possible risk factors, myopia was present in 34.5% ophkia in 29%, trauma in 9%, and lattice) degeneration was 5.4%. The study has shown a promising result for the retinal detachment surgery.

  19. Giant retinal tear after pneumatic retinopexy.

    PubMed

    Sinkar, Swati N; Simon, Sumu J; Gilhotra, Jagjit S

    2012-01-01

    To report a case with giant retinal tear after pneumatic retinopexy. To our knowledge, this is only the second case of a giant retinal tear after pneumatic retinopexy reported. This is a descriptive case study. A 43-year-old myopic man underwent pneumatic retinopexy for right eye rhegmatogenous retinal detachment. Postoperative course was complicated by a giant retinal tear, which was treated successfully. Though rare, giant retinal tears can occur after pneumatic retinopexy. The likely mechanism is increased vitreous traction because of expansion of gas in a predisposed myopic eye.

  20. ACUTE RETINAL ARTERIAL OCCLUSIVE DISORDERS

    PubMed Central

    Hayreh, Sohan Singh

    2011-01-01

    The initial section deals with basic sciences; among the various topics briefly discussed are the anatomical features of ophthalmic, central retinal and cilioretinal arteries which may play a role in acute retinal arterial ischemic disorders. Crucial information required in the management of central retinal artery occlusion (CRAO) is the length of time the retina can survive following that. An experimental study shows that CRAO for 97 minutes produces no detectable permanent retinal damage but there is a progressive ischemic damage thereafter, and by 4 hours the retina has suffered irreversible damage. In the clinical section, I discuss at length various controversies on acute retinal arterial ischemic disorders. Classification of acute retinal arterial ischemic disorders These are of 4 types: CRAO, branch retinal artery occlusion (BRAO), cotton wools spots and amaurosis fugax. Both CRAO and BRAO further comprise multiple clinical entities. Contrary to the universal belief, pathogenetically, clinically and for management, CRAO is not one clinical entity but 4 distinct clinical entities – non-arteritic CRAO, non-arteritic CRAO with cilioretinal artery sparing, arteritic CRAO associated with giant cell arteritis (GCA) and transient non-arteritic CRAO. Similarly, BRAO comprises permanent BRAO, transient BRAO and cilioretinal artery occlusion (CLRAO), and the latter further consists of 3 distinct clinical entities - non-arteritic CLRAO alone, non-arteritic CLRAO associated with central retinal vein occlusion and arteritic CLRAO associated with GCA. Understanding these classifications is essential to comprehend fully various aspects of these disorders. Central retinal artery occlusion The pathogeneses, clinical features and management of the various types of CRAO are discussed in detail. Contrary to the prevalent belief, spontaneous improvement in both visual acuity and visual fields does occur, mainly during the first 7 days. The incidence of spontaneous visual

  1. Determination of retinal surface area.

    PubMed

    Nagra, Manbir; Gilmartin, Bernard; Thai, Ngoc Jade; Logan, Nicola S

    2017-09-01

    Previous attempts at determining retinal surface area and surface area of the whole eye have been based upon mathematical calculations derived from retinal photographs, schematic eyes and retinal biopsies of donor eyes. 3-dimensional (3-D) ocular magnetic resonance imaging (MRI) allows a more direct measurement, it can be used to image the eye in vivo, and there is no risk of tissue shrinkage. The primary purpose of this study is to compare, using T2-weighted 3D MRI, retinal surface areas for superior-temporal (ST), inferior-temporal (IT), superior-nasal (SN) and inferior-nasal (IN) retinal quadrants. An ancillary aim is to examine whether inter-quadrant variations in area are concordant with reported inter-quadrant patterns of susceptibility to retinal breaks associated with posterior vitreous detachment (PVD). Seventy-three adult participants presenting without retinal pathology (mean age 26.25 ± 6.06 years) were scanned using a Siemens 3-Tesla MRI scanner to provide T2-weighted MR images that demarcate fluid-filled internal structures for the whole eye and provide high-contrast delineation of the vitreous-retina interface. Integrated MRI software generated total internal ocular surface area (TSA). The second nodal point was used to demarcate the origin of the peripheral retina in order to calculate total retinal surface area (RSA) and quadrant retinal surface areas (QRSA) for ST, IT, SN, and IN quadrants. Mean spherical error (MSE) was -2.50 ± 4.03D and mean axial length (AL) 24.51 ± 1.57 mm. Mean TSA and RSA for the RE were 2058 ± 189 and 1363 ± 160 mm 2 , respectively. Repeated measures anova for QRSA data indicated a significant difference within-quadrants (P < 0.01) which, contrasted with ST (365 ± 43 mm 2 ), was significant for IT (340 ± 40 mm 2 P < 0.01), SN (337 ± 40 mm 2 P < 0.01) and IN (321 ± 39 mm 2 P < 0.01) quadrants. For all quadrants, QRSA was significantly correlated with AL (P < 0.01) and exhibited

  2. Bilateral retinal venous occlusion in pigmentary glaucoma.

    PubMed

    Gupta, Viney; Sony, Parul; Sihota, Ramanjit

    2005-07-01

    The association of central retinal vein occlusion with primary open angle glaucoma is well known. This communication reports the occurrence of branch retinal vein occlusion and central retinal vein occlusion in a case of pigmentary glaucoma. A 32-year-old man presented with old branch retinal vein occlusion in one eye and resolving central retinal vein occlusion in the other eye. Examination revealed bilateral Krukenberg's spindle and hyperpigmented trabecular meshwork. Intraocular pressure was 30 mmHg OU. Topical antiglaucoma medication was prescribed. Intraocular pressure was controlled with topical antiglaucoma medication. The present report suggests that intraocular pressure monitoring is important in eyes even with branch retinal vein occlusion. Pigment dispersion may be the underlying cause for bilateral retinal vein occlusion, especially in young patients.

  3. Retinal ganglion cell axonal compression by retinal vessels in light-induced retinal degeneration

    PubMed Central

    García-Ayuso, Diego; Salinas-Navarro, Manuel; Agudo-Barriuso, Marta; Alarcón-Martínez, Luis; Vidal-Sanz, Manuel

    2011-01-01

    Purpose To analyze the damage produced by light in mydriatic and miotic albino retinas under two different sources of light. Methods Albino Sprague Dawley female rats were exposed to 3,000 lx during 48 h under two different light sources: linear and circular bulbs. Before exposure, their left pupils were dilated. Before and at different times after light exposure (ALE), electroretinographic signals were recorded. One week before processing, retinal ganglion cells (RGCs) were traced by applying fluorogold on the superior colliculi. Just before processing, some animals were intravenously injected with horseradish peroxidase to analyze retinal vascular leakage. At different times ALE, animals were sacrificed and their retinas dissected as whole mounts or cross-sections. Cross-sections were used to study the retinal degeneration and to detect apoptotic nuclei by the transferase dUTP nick end labeling (TUNEL) technique. Whole mounts were used to analyze vascular leakage; investigate the nerve fiber layer, identified by immunodetection of neurofilaments; and quantify the whole population of RGCs identified by fluorogold tracing and Brn3a immunodetection. With the quantitative data, detailed isodensity maps were generated to study the spatial loss of RGCs. Results Phototoxicity causes an immediate and permanent abolishment of the electroretinographic response. Early ALE, photoreceptors degenerate by apoptosis and this death is more severe in mydriatic conditions and under circular bulbs. Photoreceptor loss starts in an arciform dorsomedial retinal area, but at 3 months ALE has spread to the whole retina and there are no differences related to either pupil dilation or light source. Three months ALE, RGC axons show distorted trajectories and abnormal expression of neurofilaments. Six months or more ALE, there is significant death of RGCs caused by axonal strangulation by displaced inner retinal vessels. Topography of the surviving RGCs shows that their loss is not uniform

  4. Esperanzaite, NaCa2Al2(As5+O4)2F4(OH)*2H2O, a new mineral species from the La Esperanza mine, Mexico: descriptive mineralogy and atomic arrangement

    USGS Publications Warehouse

    Foord, E.E.; Hughes, J.M.; Cureton, F.; Maxwell, C.H.; Falster, A.U.; Sommer, A.J.; Hlava, P.F.

    1999-01-01

    Esperanzaite, ideally NaCa2Al2(As5+O4)2F4(OH)??2H2O, Z = 2, is a new mineral species from the La Esperanza mine, Durango State, Mexico. The mineral occurs as blue-green botryoidal crystalline masses on rhyolite, with separate spheres up to 1.5 mm in diameter. The Mohs hardness is 4 1/2 , and the specific gravity, 3.24 (obs.) and 3.36(3) (calc.). Optical properties were measured in 589 nm light. Esperanzaite is biaxial (-), X = Y = Z = colorless, ?? 1.580(1), ?? 1.588(1), and ?? 1.593(1); 2V(obs) is 74(1)??and 2V(calc) is 76.3??. The dispersion is medium, r < v, and the optic axes are oriented according to a ?? Z = +50.5??, b = Y, c ?? X = +35??. The strongest five X-ray-diffraction maxima in the powder pattern [d in A??(I)(hkl)] are: 2.966(100)(131, 311, 031), 3.527(90)(220), 2.700(90)(221,002,040), 5.364(80)(001,020) and 4.796(80)(011). Esperanzaite is monoclinic, a 9.687(5), b 10.7379(6), c 5.5523(7) A??, ?? 105.32(1)??, space group P21/m. The atomic arrangement of esperanzaite was solved by direct methods and Fourier analysis (R = 0.032). The Fundamental Building Block (FBB) is formed of [001] stacks of heteropolyhedral tetramers; the tetramers are formed of two arsenate tetrahedra and two Al octahedra, corner-linked in four-member rings. The FBBs are linked by irregular Na??5 and Ca??8 polyhedra.

  5. Retinitis Pigmentosa and Education Issues

    ERIC Educational Resources Information Center

    Brown, Thomas J.

    2005-01-01

    Retinitis Pigmentosa includes a number of inherited diseases which usually result in blindness. The disease is progressive in nature and begins with the deterioration of cells in the eye responsible for peripheral vision. As the condition worsens there is a gradual loss of peripheral vision and night blindness. Proper educational planning requires…

  6. Hydrothermal synthesis and crystal structures of new uranyl oxalate hydroxides: {alpha}- and {beta}-[(UO{sub 2}){sub 2}(C{sub 2}O{sub 4})(OH){sub 2}(H{sub 2}O){sub 2}] and [(UO{sub 2}){sub 2}(C{sub 2}O{sub 4})(OH){sub 2}(H{sub 2}O){sub 2}].H{sub 2}O

    SciTech Connect

    Duvieubourg, Laurence; Nowogrocki, Guy; Abraham, Francis

    2005-11-15

    Two modifications of the new uranyl oxalate hydroxide dihydrate [UO{sub 2}){sub 2}(C{sub 2}O{sub 4})(OH){sub 2}(H{sub 2}O){sub 2}] (1 and 2) and one form of the new uranyl oxalate hydroxide trihydrate [(UO{sub 2}){sub 2}(C{sub 2}O{sub 4})(OH){sub 2}(H{sub 2}O){sub 2}].H{sub 2}O (3) were synthesized by hydrothermal methods and their structures determined from single-crystal X-ray diffraction data. The crystal structures were refined by full-matrix least-squares methods to agreement indices R(wR)=0.0372(0.0842) and 0.0267(0.0671) calculated for 1096 and 1167 unique observed reflections (I>2{sigma}(I)), for {alpha} (1) and {beta} (2) forms, respectively and to R(wR)=0.0301(0.0737) calculated for 2471 unique observed reflections (I>2{sigma}(I)), for 3. The {alpha}-formmore » of the dihydrate is triclinic, space group P1-bar , Z=1, a=6.097(2), b=5.548(2), c=7.806(3)A, {alpha}=89.353(5), {beta}=94.387(5), {gamma}=97.646(5){sup o}, V=260.88(15)A{sup 3}, {beta}-form is monoclinic, space group C2/c, Z=4, a=12.180(3), b=8.223(2), c=10.777(3)A, {beta}=95.817(4), V=1073.8(5)A{sup 3}. The trihydrate is monoclinic, space group P2{sub 1}/c, Z=4, a=5.5095(12), b=15.195(3), c=13.398(3)A, {beta}=93.927(3), V=1119.0(4)A{sup 3}. In the three structures, the coordination of uranium atom is a pentagonal bipyramid composed of dioxo UO{sub 2}{sup 2+} cation perpendicular to five equatorial oxygen atoms belonging to one bidentate oxalate ion, one water molecule and two hydroxyl ions in trans configuration in 2 and in cis configuration in 1 and 3. The UO{sub 7} polyhedra are linked through hydroxyl oxygen atoms to form different structural building units, dimers [U{sub 2}O{sub 10}] obtained by edge-sharing in 1, chains [UO{sub 6}]{sub {approx}} and tetramers [U{sub 4}O{sub 26}] built by corner-sharing in 2 and 3, respectively. These units are further connected by oxalate entities that act as bis-bidentate to form one-dimensional chains in 1 and bi-dimensional network in 2 and 3. These

  7. Retinal vasculature classification using novel multifractal features

    NASA Astrophysics Data System (ADS)

    Ding, Y.; Ward, W. O. C.; Duan, Jinming; Auer, D. P.; Gowland, Penny; Bai, L.

    2015-11-01

    Retinal blood vessels have been implicated in a large number of diseases including diabetic retinopathy and cardiovascular diseases, which cause damages to retinal blood vessels. The availability of retinal vessel imaging provides an excellent opportunity for monitoring and diagnosis of retinal diseases, and automatic analysis of retinal vessels will help with the processes. However, state of the art vascular analysis methods such as counting the number of branches or measuring the curvature and diameter of individual vessels are unsuitable for the microvasculature. There has been published research using fractal analysis to calculate fractal dimensions of retinal blood vessels, but so far there has been no systematic research extracting discriminant features from retinal vessels for classifications. This paper introduces new methods for feature extraction from multifractal spectra of retinal vessels for classification. Two publicly available retinal vascular image databases are used for the experiments, and the proposed methods have produced accuracies of 85.5% and 77% for classification of healthy and diabetic retinal vasculatures. Experiments show that classification with multiple fractal features produces better rates compared with methods using a single fractal dimension value. In addition to this, experiments also show that classification accuracy can be affected by the accuracy of vessel segmentation algorithms.

  8. 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

  9. 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.

  10. [Humphrey Perimetry and Retinal Diseases].

    PubMed

    Iijima, Hiroyuki

    2016-03-01

    Since, in most eyes with retinal diseases quality of vision is greatly affected by visual field defects including paracentral scotoma and inferior field defects, visual function should be assessed by central 30- or 10-degrree automated static perimetry as well as visual acuity testing. The reduction of light sensitivity, demonstrated in the results of Humphrey central 10-2 perimetry, is more apparent than visual acuity loss in eyes with central serous chorioretinopathy (CSC), in which patients complain of dimness in the visual field of the affected eye. While reduced light sensitivity in eyes with acute CSC is well correlated with the height of subretinal fluid, marked and irreversible light sensitivity loss is demonstrated in the absence of subretinal fluid in eyes with chronic CSC due to structural damage in the photoreceptors. Various degrees of light sensitivity loss are seen in eyes wih age-related macular degeneration corresponding to intraretinal or subretinal pathology including intra- or subretinal fluid, fibrous scarring containing choroidal neovascularization and atrophic changes. The mean deviation (MD) of Humphrey central 10-2 perimetry is useful in predicting the visual outcome in eyes with exudative AMD after photodynamic therapy or intravitreal injection of anti-vascular endothelial growth factor. The progression of retinitis pigmentosa is well assssed with MD of Humphrey central 10-2 perimetry, which decreases linearly in the stage of residual visual field of 10 degrees or less. The age of patients with visual loss below 0.5 is delayed in eyes showing pencil-like configuration of "Traquair's island of visual field", in which a small area of normal light sensitivity around the fixation point is surrounded by absolute scotoma. With less visual acuity loss compared with that seen in eyes with central retinal artery occlusion; eyes with branch retinal artery occlusion show marked visual field defects, which are permanent and profound simulating the

  11. Retinitis Pigmentosa and Other Dystrophies.

    PubMed

    Mrejen, Sarah; Audo, Isabelle; Bonnel, Sébastien; Sahel, José-Alain

    2017-01-01

    Retinitis pigmentosa (RP) is a heterogeneous group of inherited retinal degenerations characterized by progressive degeneration of rod and cone cells that affects predominantly peripheral visual fields. Macular edema may cause additional central visual acuity decrease. Cystoid macular edema (CME) is one of the few treatable causes of visual loss in RP. The prevalence of CME in RP has been found to be between 10 and 20% on fluorescein angiography-based studies, and as high as 49% on reports based on optical coherence tomography. Macular edema can manifest at any stage of the disease and may be unilateral or bilateral. It can be found in any genetic form, but is more often associated with RP caused by CRB1 mutations. The origin of macular edema in RP patients still remains poorly understood. Some mechanisms have been suggested, including antiretinal antibodies (retinal, carbonic anhydrase, and enolase antibodies), vitreous traction, retinal pigment epithelium dysfunction, and Müller cell edema. There is no gold standard therapeutic strategy. Drug therapy is the primary treatment. Systemic carbonic anhydrase inhibitors, such as oral acetazolamide or topical dorzolamide, are still the mainstays of initial therapy. If CME is refractory to acetazolamide, intravitreal corticosteroid injections may be a therapeutic option. However, antivascular endothelium growth factor injections have limited effect and should be avoided. Vitrectomy has also been evaluated, but its exact role remains to be determined. The benefits of these therapies are variable among patients. The establishment of therapeutic approaches is limited by our poor understanding of the pathophysiology of CME in patients with RP. Autoimmune retinopathies (AIRs) are a group of rare diseases characterized by acute or subacute progressive vision loss and are thought to be mediated by autoantibodies specific to retinal antigens. The AIRs encompass paraneoplastic syndromes, such as cancer-associated retinopathy and

  12. High-temperature crystal chemistry of layered calcium borosilicates: CaBSiO4(OH) (datolite), Ca4B5Si3O15(OH)5 (`bakerite') and Ca2B2SiO7 (synthetic analogue of okayamalite)

    NASA Astrophysics Data System (ADS)

    Krzhizhanovskaya, Maria G.; Gorelova, L. A.; Bubnova, R. S.; Pekov, I. V.; Krivovichev, S. V.

    2017-11-01

    The high-temperature behaviour of three Ca borosilicates has been studied by in situ powder high-temperature X-ray diffraction (HTXRD), differential scanning calorimetry and thermogravimetry in the temperature range 30-900 °C for natural samples of datolite, CaBSiO4(OH), and `bakerite', Ca4B5Si3O15(OH)5, and a synthetic analogue of okayamalite, Ca2B2SiO7. The latter was obtained by heating datolite at 800 °C for 5 h. Datolite and bakerite start to dehydroxylate above 700 and 500 °C, respectively, and decompose fully to form a high-temperature modification of okayamalite, HT-Ca2B2SiO7, and wollastonite, CaSiO3 at about 730 °C. Above 900 °C, HT-okayamalite decomposes with the formation of wollastonite, CaSiO3, and metaborate CaB2O4. The latter melts at about 990 °C. Above 1000 °C, only the existence of wollastonite, CaSiO3 and cristobalite, SiO2 was observed. According to the HTXRD data, in the temperature range 30-500 °C, datolite and `bakerite' demonstrate very similar and relatively low volumetric thermal expansion: α v = 29 and 27 × 10-6 °C-1, respectively. A high thermal expansion anisotropy (α max/α min 3) is caused by both the layered character of the crystal structures and the shear deformations of their monoclinic unit cells. The direction of maximum expansion is intermediate between the normal direction to the layers and the (a + c) vector. A possible transformation mechanism from the datolite to the okayamalite structure topology is proposed from geometrical considerations. The synthetic analogue of okayamalite, Ca2B2SiO7, undergoes a reversible polymorphic transition at about 550 °C with a decrease in symmetry from tetragonal to orthorhombic. The crystal structure of the high-temperature (HT) modification of okayamalite was solved from the powder-diffraction data [900 °C: P21212, a = 7.3361(4), b = 7.1987(4), c = 4.8619(4) Å, V = 256.76(3) Å3, R wp = 6.61, R Bragg = 2.68%].

  13. Formation pathway, structural characterization and optimum processing parameters of synthetic topaz – Al{sub 2}SiO{sub 4}(OH,F){sub 2} – by CVD

    SciTech Connect

    Trujillo-Vázquez, E., E-mail: evatrujillo87@gmail.com; Pech-Canul, M.I., E-mail: martin.pech@cinvestav.edu.mx

    2015-10-15

    A novel synthesis route for topaz (Al{sub 2}SiO{sub 4}(OH,F){sub 2}) by chemical vapor deposition (CVD) using Na{sub 2}SiF{sub 6} as solid precursor was developed. Synthesis tests were conducted with and without a flow of nitrogen, positioning the Al(OH){sub 3} substrate at 0° and 90° with respect to the gas flow direction, at 700 and 750 °C, for 60 and 90 min, respectively. It was found that topaz is synthesized through two pathways, directly and indirectly, involving a series of endothermic and exothermic, heterogeneous and homogeneous reactions between Al(OH){sub 3} and SiF{sub 4}(g). Analytical structural determination confirmed existence of orthorhombic polycrystalsmore » with lattice parameters of a =4.6558 Å, b=8.8451 Å and c=8.4069 Å. According to ANOVA, while temperature, time and interaction of substrate angular position with atmosphere (P×A) are the parameters that most significantly influence the variability in the amount of topaz formed – equivalent contributions of 31% – topaz lattice parameters are mostly impacted by the same factors (T, t, P, A), but without the interaction factor. The projected amount of topaz is in good agreement with that obtained in confirmation tests under optimal conditions: Al(OH){sub 3} substrate compact placed at 0°, treated at 750 °C for 90 min in the absence of N{sub 2}. - Highlights: • Topaz synthesis as a unique phase by CVD, using solid precursor Na{sub 2}SiF{sub 6} is feasible. • Two pathways, a series of endothermic/exothermic, heterogeneous/homogeneous reactions. • Crystal structure, orthorhombic polycrystals: a =4.6558 Å, b=8.8451 Å, c=8.4069 Å. • Anova: amount of topaz formed and lattice parameters are impacted by same factors. • Projection of topaz quantity in good agreement with those from confirmation tests.« less

  14. [Peripheral retinal degenerations--treatment recommendations].

    PubMed

    Joussen, A M; Kirchhof, B

    2004-10-01

    This report reviews the clinical appearance of degenerative diseases of the peripheral retina in relationship to the risk of developing a rhegmatogenous retinal detachment. We present recommendations for preventive treatment in eyes at increased risk of developing retinal detachment. Retinal degenerations are common lesions involving the peripheral retina but most of them are clinically insignificant. Lattice degeneration, degenerative retinoschisis, cystic retinal tufts, and very rarely zonular traction tufts can result in rhegmatogenous retinal detachment. Therefore, these lesions have been considered for prophylactic treatment; however, adequate studies have not been performed to date. Most of the peripheral retinal degenerations may not require treatment except in rare, high-risk situations. According to current knowledge there is no higher incidence of secondary pucker or other side effects after laser coagulation. Therefore, generous laser indication is recommended if risk factors apply.

  15. Nonlinear retinal image enhancement for vessel detection

    NASA Astrophysics Data System (ADS)

    Wang, Xiaohong; Jiang, Xudong

    2017-07-01

    Retinal vessel detection is an essential part of the computer-aided diagnosis of eye diseases. Due to non-perfect imaging environment, retinal images often appear with intensity variations and artificial noises. This work proposes a two-step nonlinear retinal image enhancement to compensate for those imperfections of retinal images. The first step reduces intensity fluctuations of the image and the second step attenuates impulsive noise while preserving retinal vessels. Classification on the feature vector extracted from the enhanced retinal images is performed by using a linear SVM classifier. Experimental results demonstrate that the proposed method of two-step nonlinear image enhancement visibly improves the vessel detection performance, achieving better accuracy than that without enhancement process on the both DRIVE and STARE databases.

  16. [Prophylactic treatment of retinal detachment].

    PubMed

    Binder, S; Riss, B

    1981-08-01

    The indications for and results of prophylactic treatment of retinal detachment during a period of five years are reported and compared with the results in the literature. Half of the cases (3 out of 6 eyes) which developed a retinal detachment had been horse-shoe tears combined with a vitreous hemorrhage. For this reason a small buckle operation is recommended in these cases, to prevent further traction. Lattice degeneration should rather be observed than treated, except in special cases: This includes eyes where the fellow eye had a detachment from a lattice degeneration, cases in which one eye is blind from an uncured detachment or has no useful visual acuity, and eyes whose fellow eye has giant tears. In aphakic eyes treatment of lattice degeneration is recommended, because the incidence of detachment from these areas is high, especially in young aphakic cases. In one aphakic eye which had been photocoagulated several times the formation of a preretinal membrane was observed.

  17. Retinal ganglion cells in diabetes

    PubMed Central

    Kern, Timothy S; Barber, Alistair J

    2008-01-01

    Diabetic retinopathy has long been recognized as a vascular disease that develops in most patients, and it was believed that the visual dysfunction that develops in some diabetics was due to the vascular lesions used to characterize the disease. It is becoming increasingly clear that neuronal cells of the retina also are affected by diabetes, resulting in dysfunction and even degeneration of some neuronal cells. Retinal ganglion cells (RGCs) are the best studied of the retinal neurons with respect to the effect of diabetes. Although investigations are providing new information about RGCs in diabetes, including therapies to inhibit the neurodegeneration, critical information about the function, anatomy and response properties of these cells is yet needed to understand the relationship between RGC changes and visual dysfunction in diabetes. PMID:18565995

  18. Retinal Fibrosis in Diabetic Retinopathy

    PubMed Central

    Roy, Sayon; Amin, Shruti; Roy, Sumon

    2015-01-01

    In response to injury, reparative processes are triggered to restore the damaged tissue; however, such processes are not always successful in rebuilding the original state. The formation of fibrous connective tissue is known as fibrosis, a hallmark of the reparative process. For fibrosis to be successful, delicately balanced cellular events involving cell proliferation, cell migration, and extracellular matrix (ECM) remodeling must occur in a highly orchestrated manner. While successful repair may result in a fibrous scar, this often restores structural stability and functionality to the injured tissue. However, depending on the functionality of the injured tissue, a fibrotic scar can have a devastating effect. For example, in the retina, fibrotic scarring may compromise vision and ultimately lead to blindness. In this review, we discuss some of the retinal fibrotic complications and highlight mechanisms underlying the development of retinal fibrosis in diabetic retinopathy. PMID:26675403

  19. Inherited Retinal Degenerative Clinical Trial Network. Addendum

    DTIC Science & Technology

    2013-10-01

    visual impairment usually ending in blindness. In the United States, the total number of individuals affected by retinitis pigmentosa (RP) and other...linica l trial in the NEER network for autosomal dominant retinitis pigmentosa , and the ProgSTAR studies for Stargardt disease) . As new interventions b... retinitis pigmentosa continues at six sites- the CTEC site at University of Utah and five additional recruitment sites- the Retina Foundation of the

  20. Non-syndromic retinitis pigmentosa.

    PubMed

    Verbakel, Sanne K; van Huet, Ramon A C; Boon, Camiel J F; den Hollander, Anneke I; Collin, Rob W J; Klaver, Caroline C W; Hoyng, Carel B; Roepman, Ronald; Klevering, B Jeroen

    2018-03-27

    Retinitis pigmentosa (RP) encompasses a group of inherited retinal dystrophies characterized by the primary degeneration of rod and cone photoreceptors. RP is a leading cause of visual disability, with a worldwide prevalence of 1:4000. Although the majority of RP cases are non-syndromic, 20-30% of patients with RP also have an associated non-ocular condition. RP typically manifests with night blindness in adolescence, followed by concentric visual field loss, reflecting the principal dysfunction of rod photoreceptors; central vision loss occurs later in life due to cone dysfunction. Photoreceptor function measured with an electroretinogram is markedly reduced or even absent. Optical coherence tomography (OCT) and fundus autofluorescence (FAF) imaging show a progressive loss of outer retinal layers and altered lipofuscin distribution in a characteristic pattern. Over the past three decades, a vast number of disease-causing variants in more than 80 genes have been associated with non-syndromic RP. The wide heterogeneity of RP makes it challenging to describe the clinical findings and pathogenesis. In this review, we provide a comprehensive overview of the clinical characteristics of RP specific to genetically defined patient subsets. We supply a unique atlas with color fundus photographs of most RP subtypes, and we discuss the relevant considerations with respect to differential diagnoses. In addition, we discuss the genes involved in the pathogenesis of RP, as well as the retinal processes that are affected by pathogenic mutations in these genes. Finally, we review management strategies for patients with RP, including counseling, visual rehabilitation, and current and emerging therapeutic options. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. Frequency of lattice degeneration and retinal breaks in the fellow eye in retinal detachment.

    PubMed

    Lorentzen, S E

    1988-04-01

    The fellow eye of 100 consecutively admitted cases of retinal detachment was studied with three-mirror examination for the presence of lattice degeneration and retinal breaks. Lattice degeneration was found in 18% and retinal breaks in 20% of fellow eyes.

  2. [Future Developments in Retinal Prostheses].

    PubMed

    Walter, P

    2016-11-01

    Implantable retinal prostheses for the blind are already in use. In blind subjects suffering from retinitis pigmentosa (RP), these systems are able to induce phosphenes. However, the measurable gain in vision is limited. This is due to degeneration in the retina itself and to the technology, which is used in the currently available systems. Research groups and companies are working on solutions and prototypes to improve the outcome of electrical stimulation in the visual system. One improvement will be to enlarge the electrode array in order to restore a larger visual field. A second approach is to enlarge the number of electrodes and to place them at a higher density to improve the spatial resolution of the system. A third concept is to develop a recording unit within the electrode array to analyse ganglion cell behaviour underneath the electrode. This information can than be used to optimise the stimulation pattern. Not only retinal prostheses are under development but also systems to stimulate the retina from the suprachoroidal space, to directly stimulate the optic nerve or the lateral geniculate body or even the primary visual cortex. Georg Thieme Verlag KG Stuttgart · New York.

  3. Extracellular matrix remodeling during retinal development.

    PubMed

    Reinhard, Jacqueline; Joachim, Stephanie C; Faissner, Andreas

    2015-04-01

    The extracellular matrix (ECM) consists of a versatile and dynamic meshwork of proteoglycans and glycoproteins and plays an important functional role in complex tissues such as the developing retina. ECM forms the milieu surrounding retinal cells, constitutes basement membranes and provides structural as well as mechanical support. In addition, ECM molecules regulate the retinal homeostasis and cellular signaling. This review discusses the current state of ECM remodeling and its function during retinal development. In addition, we illustrate how ECM components control axonal growth and guidance of retinal ganglion cells and focus on ECM modulation during de- and regeneration processes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Retinal Macroglial Responses in Health and Disease.

    PubMed

    de Hoz, Rosa; Rojas, Blanca; Ramírez, Ana I; Salazar, Juan J; Gallego, Beatriz I; Triviño, Alberto; Ramírez, José M

    2016-01-01

    Due to their permanent and close proximity to neurons, glial cells perform essential tasks for the normal physiology of the retina. Astrocytes and Müller cells (retinal macroglia) provide physical support to neurons and supplement them with several metabolites and growth factors. Macroglia are involved in maintaining the homeostasis of extracellular ions and neurotransmitters, are essential for information processing in neural circuits, participate in retinal glucose metabolism and in removing metabolic waste products, regulate local blood flow, induce the blood-retinal barrier (BRB), play fundamental roles in local immune response, and protect neurons from oxidative damage. In response to polyetiological insults, glia cells react with a process called reactive gliosis, seeking to maintain retinal homeostasis. When malfunctioning, macroglial cells can become primary pathogenic elements. A reactive gliosis has been described in different retinal pathologies, including age-related macular degeneration (AMD), diabetes, glaucoma, retinal detachment, or retinitis pigmentosa. A better understanding of the dual, neuroprotective, or cytotoxic effect of macroglial involvement in retinal pathologies would help in treating the physiopathology of these diseases. The extensive participation of the macroglia in retinal diseases points to these cells as innovative targets for new drug therapies.

  5. Retinal Macroglial Responses in Health and Disease

    PubMed Central

    de Hoz, Rosa; Rojas, Blanca; Ramírez, Ana I.; Salazar, Juan J.; Gallego, Beatriz I.; Triviño, Alberto; Ramírez, José M.

    2016-01-01

    Due to their permanent and close proximity to neurons, glial cells perform essential tasks for the normal physiology of the retina. Astrocytes and Müller cells (retinal macroglia) provide physical support to neurons and supplement them with several metabolites and growth factors. Macroglia are involved in maintaining the homeostasis of extracellular ions and neurotransmitters, are essential for information processing in neural circuits, participate in retinal glucose metabolism and in removing metabolic waste products, regulate local blood flow, induce the blood-retinal barrier (BRB), play fundamental roles in local immune response, and protect neurons from oxidative damage. In response to polyetiological insults, glia cells react with a process called reactive gliosis, seeking to maintain retinal homeostasis. When malfunctioning, macroglial cells can become primary pathogenic elements. A reactive gliosis has been described in different retinal pathologies, including age-related macular degeneration (AMD), diabetes, glaucoma, retinal detachment, or retinitis pigmentosa. A better understanding of the dual, neuroprotective, or cytotoxic effect of macroglial involvement in retinal pathologies would help in treating the physiopathology of these diseases. The extensive participation of the macroglia in retinal diseases points to these cells as innovative targets for new drug therapies. PMID:27294114

  6. Flickering light increases retinal blood flow.

    PubMed

    Michelson, George; Patzelt, Alexander; Harazny, Joana

    2002-06-01

    To examine the retinal blood flow in normal eyes before and during retinal stimulation by flickering light. A prospective cross-sectional study. PARTICIPANTS AND TESTING: Twenty-seven eyes of 27 normal subjects with a mean age +/- SD of 38 +/- 15 years (study I) and 21 eyes of 21 normal subjects with a mean age +/- SD of 46 +/- 17 years (study II) were examined with respect to capillary retinal blood flow and central retinal artery and central retinal vein blood flow velocities during flickering light stimulation. A luminance flicker light with a frequency of 8 Hz increased the neuronal activity of retinal ganglion cells. In study I, the retinal capillary blood flow was measured before and during flickering by scanning laser Doppler flowmetry (670 nm, Heidelberg Retina Flowmeter). In study II, the blood flow velocities in the central retinal artery and central retinal vein were examined by pulsed Doppler sonography. Change in blood flow velocities in the central retinal artery and vein and in retinal capillary blood flow after full-field flicker stimulation. In study I, measurements of blood flow during retinal flicker stimulation showed a significant increase in the mean value of blood flow +/- SD from 317 +/- 72 arbitrary units to 416 +/- 103 arbitrary units. The change was on average 46 +/- 19%. In study II, the systolic and end-diastolic blood flow velocities in the central retinal artery increased significantly (P < 0.0001): systolic, 9 cm/s to 15 cm/s (+62%); end-diastolic, 2.7 cm/s to 5.3 cm/s (+96%). In the central retinal vein, the systolic and end-diastolic blood flow velocities increased significantly (P < 0.0001): systolic, 4.3 cm/s to 6.7 cm/s (+56%); end-diastolic, 1.8 cm/s to 3.6 cm/s (+100%). The authors found no significant change in blood pressure and heartbeat frequency. Visual stimulation of the retina by flickering light strongly increased the juxtapapillary retinal capillary blood flow and central retinal artery blood flow velocity in normal

  7. Crewmembers in the middeck with the Retinal Photography experiment.

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Mission Pilot Robert Cabana conducting the Retinal Photography life sciences experiment on test subject Mission Specialist Michael Clifford. The Retinal Photography experiment is Detailed Supplementary Objective # 474.

  8. ADULT WITH CHICKENPOX COMPLICATED BY SYSTEMIC VASCULITIS AND BILATERAL RETINAL VASCULITIS WITH RETINAL VASCULAR OCCLUSIONS.

    PubMed

    Murdock, Jennifer; Carvounis, Petros E

    2017-01-01

    To describe an adult with chickenpox resulting in systemic vasculitis and bilateral retinal vascular occlusions. Single case report. A 58-year-old man with chickenpox complicated by disseminated varicella-zoster systemic and retinal vasculitis resulting in a combined arterial and venous occlusion in one eye with multiple branch retinal vein occlusions in the other eye. There was no evidence of retinitis. The patient systemically improved after treatment with acyclovir and steroids; however, his vision remained poor. Chickenpox can be associated with systemic vasculopathy and may rarely result in multiple systemic and ocular infarcts, including severe retinal vascular occlusions.

  9. Topographic changes of retinal layers after resolution of acute retinal detachment.

    PubMed

    Kim, Jae Hui; Park, Do Young; Ha, Hyo Shin; Kang, Se Woong

    2012-10-23

    To investigate changes in thickness profiles of retinal layers after resolution of recent onset rhegmatogenous retinal detachment Spectral domain optical coherence tomography (SD-OCT) scans were performed for 28 patients diagnosed with unilateral inferior half or superior half retinal detachment who underwent retinal reattachment surgery. The thickness of each retinal layer was measured at 3000 μm and 2800 μm in the superior and inferior directions from the foveal center. The thicknesses of each retinal layer of the reattached retina were compared with those of the undetached region of the retina of the same eye. Sixteen patients were diagnosed with superior half and 12 patients were diagnosed with inferior half retinal detachment. The mean duration of retinal detachment was 6.9 ± 3.9 days. SD-OCT scans were performed 10.4 ± 6.9 months after the surgery. The thicknesses of the outer nuclear layer and photoreceptor layer in the reattached retina were significantly thinner than those of the undetached retina (P = 0.012, and P = 0.018, respectively). Our findings suggest that prominent retinal structural sequelae, especially in outer nuclear layer and photoreceptor layer, can be induced by a short duration of retinal detachment. Our findings also underscore the important role of initial retinal injuries that occur within the first several days on the long term structural prognosis. (ClinicalTrials.gov number, NCT01587794).

  10. How Methylation Modifies the Photophysics of the Native All- trans-Retinal Protonated Schiff Base: A CASPT2/MD Study in Gas Phase and in Methanol.

    PubMed

    Barata-Morgado, Rute; Sánchez, M Luz; Muñoz-Losa, Aurora; Martín, M Elena; Olivares Del Valle, Francisco J; Aguilar, Manuel A

    2018-03-22

    A comparison between the free-energy surfaces of the all- trans-retinal protonated Schiff base (RPSB) and its 10-methylated derivative in gas phase and methanol solution is performed at CASSCF//CASSCF and CASPT2//CASSCF levels. Solvent effects were included using the average solvent electrostatic potential from molecular dynamics method. This is a QM/MM (quantum mechanics/molecular mechanics) method that makes use of the mean field approximation. It is found that the methyl group bonded to C10 produces noticeable changes in the solution free-energy profile of the S 1 excited state, mainly in the relative stability of the minimum energy conical intersections (MECIs) with respect to the Franck-Condon (FC) point. The conical intersections yielding the 9- cis and 11- cis isomers are stabilized while that yielding the 13- cis isomer is destabilized; in fact, it becomes inaccessible by excitation to S 1 . Furthermore, the planar S 1 minimum is not present in the methylated compound. The solvent notably stabilizes the S 2 excited state at the FC geometry. Therefore, if the S 2 state has an effect on the photoisomerization dynamics, it must be because it permits the RPSB population to branch around the FC point. All these changes combine to speed up the photoisomerization in the 10-methylated compound with respect to the native compound.

  11. Tatarinovite Ca3Al(SO4)[B(OH)4](OH)6 · 12H2O, a new ettringite-group mineral from the Bazhenovskoe deposit, Middle Urals, Russia, and its crystal structure

    NASA Astrophysics Data System (ADS)

    Chukanov, N. V.; Kasatkin, A. V.; Zubkova, N. V.; Britvin, S. N.; Pautov, L. A.; Pekov, I. V.; Varlamov, D. A.; Bychkova, Ya. V.; Loskutov, A. B.; Novgorodova, E. A.

    2016-12-01

    A new mineral, tatarinovite, ideally Ca3Al(SO4)[B(OH)4](OH)6 · 12H2O, has been found in cavities of rhodingites at the Bazhenovskoe chrysotile asbestos deposit, Middle Urals, Russia. It occurs (1) colorless, with vitreous luster, bipyramidal crystals up to 1 mm across in cavities within massive diopside, in association with xonotlite, clinochlore, pectolite and calcite, and (2) as white granular aggregates up to 5 mm in size on grossular with pectolite, diopside, calcite, and xonotlite. The Mohs hardness is 3; perfect cleavage on (100) is observed. D meas = 1.79(1), D calc = 1.777 g/cm3. Tatarinovite is optically uniaxial (+), ω = 1.475(2), ɛ = 1.496(2). The IR spectrum contains characteristic bands of SO4 2-, CO3 2-, B(OH)4 -, B(OH)3, Al(OH)6 3-, Si(OH)6 2-, OH-, and H2O. The chemical composition of tatarinovite (wt %; ICP-AES; H2O was determined by the Alimarin method; CO2 was determined by selective sorption on askarite) is as follows: 27.40 CaO, 4.06 B2O3, 6.34 A12O3, 0.03 Fe2O3, 2.43 SiO2, 8.48 SO3, 4.2 CO2, 46.1 H2O, total is 99.04. The empirical formula (calculated on the basis of 3Ca apfu) is H31.41Ca3.00(Al0.76Si0.25)Σ1.01 · (B0.72S0.65C0.59)Σ1.96O24.55. Tatarinovite is hexagonal, space gr. P63, a = 11.1110(4) Å, c = 10.6294(6) Å, V = 1136.44(9) A3, Z = 2. Its crystal chemical formula is Ca3(Al0.70Si0.30) · {[SO4]0.34[B(OH)4]0.33[CO3]0.24}{[SO4]0.30[B(OH)4]0.34[CO3]0.30[B(OH)3]0.06}(OH5·73O0.27) · 12H2O. The strongest reflections of the powder X-ray diffraction pattern [ d, Å ( I, %) ( hkl)] are 9.63 (100) (100), 5.556 (30) (110), 4.654 (14) (102), 3.841 (21) (112), 3.441 (12) (211), 2.746 (10) (302), 2.538 (12) (213). Tatarinovite was named in memory of the Russian geologist and petrologist Pavel Mikhailovich Tatarinov (1895-1976), a well-known specialist in chrysotile asbestos deposits. Type specimens have been deposited at the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow.

  12. Peripheral Pigmented Retinal Lesions in Stargardt Disease.

    PubMed

    Zhao, Peter Y; Abalem, Maria Fernanda; Nadelman, Daniel; Qian, Cynthia X; Branham, Kari; Schlegel, Dana; Khan, Naheed; Heckenlively, John R; Jayasundera, Thiran

    2018-04-01

    To investigate the prevalence of peripheral pigmented retinal lesions and associated clinical findings in patients with Stargardt disease. Retrospective case series. Records at a single academic institution were reviewed for patients with genetically confirmed Stargardt disease with peripheral pigmented retinal lesions on wide-field retinal imaging. For this cohort we described demographics, clinical features, and pathogenic variants. Out of 62 patients with Stargardt disease and wide-field retinal imaging, 14 had peripheral pigmented retinal lesions. These flat, subretinal lesions were located in the mid or far periphery and had well-defined borders, resembling congenital hypertrophy of retinal pigment epithelium (CHRPE) lesions. For this group of 14 patients, median age at initial diagnosis of Stargardt disease was 9.5 years, and the median duration of disease was 21.5 years. Median Snellen visual acuity was 20/200, and median central scotoma size was 20.0 degrees. All 14 patients had electroretinographic abnormalities. Four out of 14 patients developed new lesions during clinical follow-up. Wide-field retinal imaging revealed the presence of peripheral pigmented retinal lesions resembling CHRPE lesions in a subset of patients with genetically confirmed Stargardt disease. Presence of these lesions may be associated with severe phenotypes of the disease. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Imaging of retinal and choroidal vascular tumours

    PubMed Central

    Heimann, H; Jmor, F; Damato, B

    2013-01-01

    The most common intraocular vascular tumours are choroidal haemangiomas, vasoproliferative tumours, and retinal haemangioblastomas. Rarer conditions include cavernous retinal angioma and arteriovenous malformations. Options for ablating the tumour include photodynamic therapy, argon laser photocoagulation, trans-scleral diathermy, cryotherapy, anti-angiogenic agents, plaque radiotherapy, and proton beam radiotherapy. Secondary effects are common and include retinal exudates, macular oedema, epiretinal membranes, retinal fibrosis, as well as serous and tractional retinal detachment, which are treated using standard methods (ie, intravitreal anti-angiogenic agents or steroids as well as vitreoretinal procedures, such as epiretinal membrane peeling and release of retinal traction). The detection, diagnosis, and monitoring of vascular tumours and their complications have improved considerably thanks to advances in imaging. These include spectral domain and enhanced depth imaging optical coherence tomography (SD-OCT and EDI-OCT, respectively), wide-angle photography and angiography as well as wide-angle fundus autofluorescence. Such novel imaging has provided new diagnostic clues and has profoundly influenced therapeutic strategies so that vascular tumours and secondary effects are now treated concurrently instead of sequentially, enhancing any opportunities for conserving vision and the eye. In this review, we describe how SD-OCT, EDI-OCT, autofluorescence, wide-angle photography and wide-angle angiography have facilitated the evaluation of eyes with the more common vascular tumours, that is, choroidal haemangioma, retinal vasoproliferative tumours, and retinal haemangioblastoma. PMID:23196648

  14. CRB1 mutations in inherited retinal dystrophies

    PubMed Central

    Bujakowska, Kinga; Audo, Isabelle; Mohand-Saïd, Saddek; Lancelot, Marie-Elise; Antonio, Aline; Germain, Aurore; Léveillard, Thierry; Letexier, Mélanie; Saraiva, Jean-Paul; Lonjou, Christine; Carpentier, Wassila; Sahel, José-Alain; Bhattacharya, Shomi S.; Zeitz, Christina

    2011-01-01

    Mutations in the CRB1 gene are associated with variable phenotypes of severe retinal dystrophies, ranging from Leber Congenital Amaurosis (LCA) to rod-cone dystrophy (also called retinitis pigmentosa (RP)). Moreover, retinal dystrophies resulting from CRB1 mutations may be accompanied by specific fundus features: preservation of the para-arteriolar retinal pigment epithelium (PPRPE) and retinal telangiectasia with exudation (also referred to as Coats-like vasculopathy). In this publication we report seven novel mutations and classify over 150 reported CRB1 sequence variants that were found in more that 240 patients. The data from previous reports was used to analyse a potential correlation between CRB1 variants and the clinical features of respective patients. This meta-analysis suggests that the differential phenotype of patients with CRB1 mutations is due to additional modifying factors rather than particular mutant allele combination. PMID:22065545

  15. THE CELL STRESS MACHINERY AND RETINAL DEGENERATION

    PubMed Central

    Athanasiou, Dimitra; Aguilà, Monica; Bevilacqua, Dalila; Novoselov, Sergey S.; Parfitt, David A.; Cheetham, Michael E.

    2015-01-01

    Retinal degenerations are a group of clinically and genetically heterogeneous disorders characterised by progressive loss of vision due to neurodegeneration. The retina is a highly specialised tissue with a unique architecture and maintaining homeostasis in all the different retinal cell types is crucial for healthy vision. The retina can be exposed to a variety of environmental insults and stress, including light-induced damage, oxidative stress and inherited mutations that can lead to protein misfolding. Within retinal cells there are different mechanisms to cope with disturbances in proteostasis, such as the heat shock response, the unfolded protein response and autophagy. In this review, we discuss the multiple responses of the retina to different types of stress involved in retinal degenerations, such as retinitis pigmentosa, age-related macular degeneration and glaucoma. Understanding the mechanisms that maintain and re-establish proteostasis in the retina is important for developing new therapeutic approaches to fight blindness. PMID:23684651

  16. Rhegmatogenous retinal detachment and uveitis.

    PubMed

    Kerkhoff, Frank T; Lamberts, Querin J; van den Biesen, Pieter R; Rothova, Aniki

    2003-02-01

    To evaluate the frequency, high-risk factors, and visual prognosis of rhegmatogenous retinal detachment (RRD) in patients with uveitis. Retrospective case-control study. We included 1387 consecutive patients with uveitis who consulted our uveitis clinic from January 1990 through December 1997 of whom 43 patients (46 eyes) with RRD were identified. The retinal detachment (RD) controls were 212 consecutive patients with RRD (221 eyes, first occurrence of RD, not associated with uveitis) who were admitted for surgery in the period from April 1999 to April 2000. The uveitis control group consisted of 150 age-matched patients (210 eyes) selected from the entire uveitis series. Retrospective analysis of clinical data. The presence of RRD and eventual risk factors for RRD, such as myopia, retinal lattice degeneration, prior intraocular surgery, anatomic location of uveitis, its specific diagnosis, and clinical manifestations. Furthermore, the surgical and nonsurgical outcomes of RRD, as well as the results of various treatment regimens, were analyzed. RRD was identified in 3.1% of the patients with uveitis. RRD was most frequently associated with panuveitis (6.6%). RRD was associated more frequently with infectious (7.6%) than noninfectious uveitis (2.1%). At the onset of RRD, uveitis was active in most (46%) affected eyes. Proliferative vitreoretinopathy was present in 30% of the uveitic RRD eyes at presentation in contrast to 12% of the RRD control eyes. In uveitic RRD, the retina was reattached in 59% of eyes with a single operation; the final anatomic reattachment rate was 88%. Finally, a visual acuity of less than 20/200 was present in 71% of the uveitic RRD eyes, 10% of which had no light perception. We discovered a high prevalence of RRD in patients with active panuveitis and infectious uveitis and document that uveitis in itself is a risk factor for the development of RRD. The visual prognosis of RRD in uveitis was poor because of the uveitis itself and the

  17. Retinal Implants for Blind Patients

    NASA Astrophysics Data System (ADS)

    Rothermel, Albrecht

    Recently, very promising results have been obtained in clinical trials with eye-prostheses for the blind. There is a chance that advances in surgical techniques, microelectronics design, and material science may lead to the first really useful applications of retinal implants in the near future. This chapter will focus on the actual status of subretinal surgery and implant technologies. Opportunities and limitations of the different technologies will be discussed in terms of patients benefit and technological challenges. Finally, a vision on how the devices may work and look like in the future will be given.

  18. Interventions for asymptomatic retinal breaks and lattice degeneration for preventing retinal detachment.

    PubMed

    Wilkinson, C

    2005-01-25

    Asymptomatic retinal breaks and lattice degeneration are visible lesions that are risk factors for later retinal detachment. Retinal detachments occur when fluid in the vitreous cavity passes through tears or holes in the retina and separates the retina from the underlying retinal pigment epithelium. Creation of an adhesion surrounding retinal breaks and lattice degeneration, with laser photocoagulation or cryotherapy, has been recommended as an effective means of preventing retinal detachment. This therapy is of value in the management of retinal tears associated with the symptoms of flashes and floaters and persistent vitreous traction upon the retina in the region of the retinal break, because such symptomatic retinal tears are associated with a high rate of progression to retinal detachment. Retinal tears and holes unassociated with acute symptoms and lattice degeneration are significantly less likely to be the sites of retinal breaks that are responsible for later retinal detachment. Nevertheless, treatment of these problems is frequently recommended, in spite of the fact that the effectiveness of this therapy is unproven. The purpose of this review is to evaluate the effectiveness of interventions for asymptomatic retinal breaks and lattice degeneration. We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which includes the Cochrane Eyes and Vision Group Trials Register) on The Cochrane Library (Issue 3 2004) MEDLINE (1966 to July 2004) and EMBASE (1980 to August 2004). Textbooks regarding retinal detachment and the reference lists of relevant reports were reviewed for additional study reports. Experts in the field were contacted for details of other published and unpublished studies. This review was designed to include randomised controlled trials in which one treatment for asymptomatic retinal breaks and lattice degeneration was compared to another treatment or to no treatment. One reviewer assessed the search results and collected

  19. Interventions for asymptomatic retinal breaks and lattice degeneration for preventing retinal detachment.

    PubMed

    Wilkinson, Charles P

    2012-03-14

    Asymptomatic retinal breaks and lattice degeneration are visible lesions that are risk factors for later retinal detachment. Retinal detachments occur when fluid in the vitreous cavity passes through tears or holes in the retina and separates the retina from the underlying retinal pigment epithelium. Creation of an adhesion surrounding retinal breaks and lattice degeneration, with laser photocoagulation or cryotherapy, has been recommended as an effective means of preventing retinal detachment. This therapy is of value in the management of retinal tears associated with the symptoms of flashes and floaters and persistent vitreous traction upon the retina in the region of the retinal break, because such symptomatic retinal tears are associated with a high rate of progression to retinal detachment. Retinal tears and holes unassociated with acute symptoms and lattice degeneration are significantly less likely to be the sites of retinal breaks that are responsible for later retinal detachment. Nevertheless, treatment of these problems is frequently recommended, in spite of the fact that the effectiveness of this therapy is unproven. The purpose of this review was to evaluate the effectiveness of interventions for asymptomatic retinal breaks and lattice degeneration. We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 1), MEDLINE (January 1950 to January 2012), EMBASE (January 1980 to January 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 28 January 2012. Textbooks regarding retinal detachment and the reference lists of relevant reports were reviewed for additional study reports. Experts in the field

  20. Interventions for asymptomatic retinal breaks and lattice degeneration for preventing retinal detachment

    PubMed Central

    Wilkinson, Charles P

    2016-01-01

    Background Asymptomatic retinal breaks and lattice degeneration are visible lesions that are risk factors for later retinal detachment. Retinal detachments occur when fluid in the vitreous cavity passes through tears or holes in the retina and separates the retina from the underlying retinal pigment epithelium. Creation of an adhesion surrounding retinal breaks and lattice degeneration, with laser photocoagulation or cryotherapy, has been recommended as an effective means of preventing retinal detachment. This therapy is of value in the management of retinal tears associated with the symptoms of flashes and floaters and persistent vitreous traction upon the retina in the region of the retinal break, because such symptomatic retinal tears are associated with a high rate of progression to retinal detachment. Retinal tears and holes unassociated with acute symptoms and lattice degeneration are significantly less likely to be the sites of retinal breaks that are responsible for later retinal detachment. Nevertheless, treatment of these problems is frequently recommended, in spite of the fact that the effectiveness of this therapy is unproven. Objectives The purpose of this review was to evaluate the effectiveness of interventions for asymptomatic retinal breaks and lattice degeneration. Search methods We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 1), MEDLINE (January 1950 to January 2012), EMBASE (January 1980 to January 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 28 January 2012. Textbooks regarding retinal detachment and the reference lists of relevant reports were reviewed for additional

  1. Cell Therapy Applications for Retinal Vascular Diseases: Diabetic Retinopathy and Retinal Vein Occlusion.

    PubMed

    Park, Susanna S

    2016-04-01

    Retinal vascular conditions, such as diabetic retinopathy and retinal vein occlusion, remain leading causes of vision loss. No therapy exists to restore vision loss resulting from retinal ischemia and associated retinal degeneration. Tissue regeneration is possible with cell therapy. The goal would be to restore or replace the damaged retinal vasculature and the retinal neurons that are damaged and/or degenerating from the hypoxic insult. Currently, various adult cell therapies have been explored as potential treatment. They include mesenchymal stem cells, vascular precursor cells (i.e., CD34+ cells, hematopoietic cells or endothelial progenitor cells), and adipose stromal cells. Preclinical studies show that all these cells have a paracrine trophic effect on damaged ischemic tissue, leading to tissue preservation. Endothelial progenitor cells and adipose stromal cells integrate into the damaged retinal vascular wall in preclinical models of diabetic retinopathy and ischemia-reperfusion injury. Mesenchymal stem cells do not integrate as readily but appear to have a primary paracrine trophic effect. Early phase clinical trials have been initiated and ongoing using mesenchymal stem cells or autologous bone marrow CD34+ cells injected intravitreally as potential therapy for diabetic retinopathy or retinal vein occlusion. Adipose stromal cells or pluripotent stem cells differentiated into endothelial colony-forming cells have been explored in preclinical studies and show promise as possible therapies for retinal vascular disorders. The relative safety or efficacy of these various cell therapies for treating retinal vascular disorders have yet to be determined.

  2. Measurement of retinal blood velocity

    NASA Astrophysics Data System (ADS)

    Winchester, Leonard W., Jr.; Chou, Nee-Yin

    2006-02-01

    A fundus camera was modified to illuminate the retina of a rabbit model with low power laser light in order to obtain laser speckle images. A fast-exposure charge-coupled device (CCD) camera was used to capture laser speckle images of the retina. Image acquisition was synchronized with the arterial pulses of the rabbit to ensure that all images are obtained at the same point in the cardiac cycle. The rabbits were sedated and a speculum was inserted to prevent the eyelid from closing. Both albino (New Zealand; pigmented (Dutch belted) rabbits were used in the study. The rabbit retina is almost avascular. The measurements are obtained for choroidal tissue as well as retinal tissue. Because the retina is in a region of high metabolism, blood velocity is strongly affected by blood oxygen saturation. Measurements of blood velocity obtained over a wide range of O II saturations (58%-100%) showed that blood velocity increases with decreasing O II saturation. For most experiments, the left eye of the rabbit was used for laser measurements whereas the right eye served as a control. No observable difference between pre- and post-experimented eye was noted. Histological examinations of retinal tissue subjected to repeated laser measurements showed no indication of tissue damage.

  3. Fixation Strategies For Retinal Immunohistochemistry

    PubMed Central

    Stradleigh, Tyler W.; Ishida, Andrew T.

    2015-01-01

    Immunohistochemical and ex vivo anatomical studies have provided many glimpses of the variety, distribution, and signaling components of vertebrate retinal neurons. The beauty of numerous images published to date, and the qualitative and quantitative information they provide, indicate that these approaches are fundamentally useful. However, obtaining these images entailed tissue handling and exposure to chemical solutions that differ from normal extracellular fluid in composition, temperature, and osmolarity. Because the differences are large enough to alter intercellular and intracellular signaling in neurons, and because retinae are susceptible to crush, shear, and fray, it is natural to wonder if immunohistochemical and anatomical methods disturb or damage the cells they are designed to examine. Tissue fixation is typically incorporated to guard against this damage and is therefore critically important to the quality and significance of the harvested data. Here, we describe mechanisms of fixation; advantages and disadvantages of using formaldehyde and glutaraldehyde as fixatives during immunohistochemistry; and modifications of widely used protocols that have recently been found to improve cell shape preservation and immunostaining patterns, especially in proximal retinal neurons. PMID:25892361

  4. Interventions for asymptomatic retinal breaks and lattice degeneration for preventing retinal detachment.

    PubMed

    Wilkinson, C

    2001-01-01

    Asymptomatic retinal breaks and lattice degeneration are visible lesions that are risk factors for later retinal detachment. Retinal detachments occur when fluid in the vitreous cavity passes through tears or holes in the retina and separates the retina from the underlying retinal pigment epithelium. Creation of an adhesion surrounding retinal breaks and lattice degeneration, with laser photocoagulation or cryotherapy, has been recommended as an effective means of preventing retinal detachment. This therapy is of value in the management of retinal tears associated with the symptoms of flashes and floaters and persistent vitreous traction upon the retina, because such symptomatic retinal breaks are associated with a high rate of progression to retinal detachment. Retinal tears and holes unassociated with acute symptoms and lattice degeneration are significantly less likely to be the sites of retinal breaks that are responsible for later retinal detachment. Nevertheless, treatment of these problems is frequently recommended, in spite of the fact that the effectiveness of this therapy is unproven. The purpose of this review is to evaluate the effects of interventions for asymptomatic retinal breaks and lattice degeneration. We searched the Cochrane Controlled Trials Register - CENTRAL (which includes the Cochrane Eyes and Vision Group specialized register), MEDLINE and EMBASE. Textbooks regarding retinal detachment and the reference lists of relevant reports were reviewed in an effort to find additional study reports. Experts in the field were contacted for details of other published and unpublished studies. This review was designed to include randomised controlled trials in which one treatment for asymptomatic retinal breaks and lattice degeneration was compared to another treatment or to no treatment. One reviewer assessed the search results and collected relevant studies. Since no studies met the inclusion criteria, no studies were assessed for methodological

  5. Optical Coherence Tomography Angiography in Retinal Diseases

    PubMed Central

    Chalam, K. V.; Sambhav, Kumar

    2016-01-01

    Optical coherence tomography angiography (OCTA) is a new, non-invasive imaging system that generates volumetric data of retinal and choroidal layers. It has the ability to show both structural and blood flow information. Split-spectrum amplitude-decorrelation angiography (SSADA) algorithm (a vital component of OCTA software) helps to decrease the signal to noise ratio of flow detection thus enhancing visualization of retinal vasculature using motion contrast. Published studies describe potential efficacy for OCTA in the evaluation of common ophthalmologic diseases such as diabetic retinopathy, age related macular degeneration (AMD), retinal vascular occlusions and sickle cell disease. OCTA provides a detailed view of the retinal vasculature, which allows accurate delineation of microvascular abnormalities in diabetic eyes and vascular occlusions. It helps quantify vascular compromise depending upon the severity of diabetic retinopathy. OCTA can also elucidate the presence of choroidal neovascularization (CNV) in wet AMD. In this paper, we review the knowledge, available in English language publications regarding OCTA, and compare it with the conventional angiographic standard, fluorescein angiography (FA). Finally, we summarize its potential applications to retinal vascular diseases. Its current limitations include a relatively small field of view, inability to show leakage, and tendency for image artifacts. Further larger studies will define OCTA's utility in clinical settings and establish if the technology may offer a non-invasive option of visualizing the retinal vasculature, enabling us to decrease morbidity through early detection and intervention in retinal diseases. PMID:27195091

  6. A mechanical model of retinal detachment

    NASA Astrophysics Data System (ADS)

    Chou, Tom; Siegel, Michael

    2012-08-01

    We present a model of the mechanical and fluid forces associated with exudative retinal detachments where the retinal photoreceptor cells separate, typically from the underlying retinal pigment epithelium (RPE). By computing the total fluid volume flow arising from transretinal, vascular and RPE pump currents, we determine the conditions under which the subretinal fluid pressure exceeds the maximum yield stress holding the retina and RPE together, giving rise to an irreversible, extended retinal delamination. We also investigate localized, blister-like retinal detachments by balancing mechanical tension in the retina with both the retina-RPE adhesion energy and the hydraulic pressure jump across the retina. For detachments induced by traction forces, we find a critical radius beyond which the blister is unstable to growth. Growth of a detached blister can also be driven by inflamed lesions in which the tissue has a higher choroidal hydraulic conductivity, has insufficient RPE pump activity, or has defective adhesion bonds. We determine the parameter regimes in which the blister either becomes unstable to growth, remains stable and finite-sized, or shrinks, allowing possible healing. The corresponding stable blister radius and shape are calculated. Our analysis provides a quantitative description of the physical mechanisms involved in exudative retinal detachments and can help guide the development of retinal reattachment protocols or preventative procedures.

  7. Digital tracking and control of retinal images

    NASA Astrophysics Data System (ADS)

    Barrett, Steven F.; Jerath, Maya R.; Rylander, Henry G., III; Welch, Ashley J.

    1993-06-01

    Laser induced retinal lesions are used to treat a variety of eye diseases such as diabetic retinopathy and retinal detachment. An instrumentation system has been developed to track a specific lesion coordinate on the retinal surface and provide corrective signals to maintain laser position on the coordinate. High resolution retinal images are acquired via a CCD camera coupled to a fundus camera and video frame grabber. Optical filtering and histogram modification are used to enhance the retinal vessel network against the lighter retinal background. Six distinct retinal landmarks are tracked on the high contrast image obtained from the frame grabber using two-dimensional blood vessel templates. The frame grabber is hosted on a 486 PC. The PC performs correction signal calculations using an exhaustive search on selected image portions. An X and Y laser correction signal is derived from the landmark tracking information and provided to a pair of galvanometer steered mirrors via a data acquisition and control subsystem. This subsystem also responds to patient inputs and the system monitoring lesion growth. This paper begins with an overview of the robotic laser system design followed by implementation and testing of a development system for proof of concept. The paper concludes with specifications for a real time system.

  8. Optical Coherence Tomography Angiography in Retinal Diseases.

    PubMed

    Chalam, K V; Sambhav, Kumar

    2016-01-01

    Optical coherence tomography angiography (OCTA) is a new, non-invasive imaging system that generates volumetric data of retinal and choroidal layers. It has the ability to show both structural and blood flow information. Split-spectrum amplitude-decorrelation angiography (SSADA) algorithm (a vital component of OCTA software) helps to decrease the signal to noise ratio of flow detection thus enhancing visualization of retinal vasculature using motion contrast. Published studies describe potential efficacy for OCTA in the evaluation of common ophthalmologic diseases such as diabetic retinopathy, age related macular degeneration (AMD), retinal vascular occlusions and sickle cell disease. OCTA provides a detailed view of the retinal vasculature, which allows accurate delineation of microvascular abnormalities in diabetic eyes and vascular occlusions. It helps quantify vascular compromise depending upon the severity of diabetic retinopathy. OCTA can also elucidate the presence of choroidal neovascularization (CNV) in wet AMD. In this paper, we review the knowledge, available in English language publications regarding OCTA, and compare it with the conventional angiographic standard, fluorescein angiography (FA). Finally, we summarize its potential applications to retinal vascular diseases. Its current limitations include a relatively small field of view, inability to show leakage, and tendency for image artifacts. Further larger studies will define OCTA's utility in clinical settings and establish if the technology may offer a non-invasive option of visualizing the retinal vasculature, enabling us to decrease morbidity through early detection and intervention in retinal diseases.

  9. Silver nano - a trove for retinal therapies.

    PubMed

    Kalishwaralal, Kalimuthu; Barathmanikanth, Selvaraj; Pandian, Sureshbabu Ram Kumar; Deepak, Venkatraman; Gurunathan, Sangiliyandi

    2010-07-14

    Pathological retinal angiogenesis (neovascularization) is one of the most feared complications among retinal diseases, leading to visual impairment and irreversible blindness. Recent findings made by us on therapeutic applications of biologically synthesized silver nanoparticles (AgNPs) against VEGF induced retinal endothelial cells, elucidates the effectual inhibitory activities of AgNPs over the downstream signaling pathways (Src and AKT/PI3K) leading to retinal angiogenesis. The current review focuses on the imperative role of VEGF induced angiogenesis in the development of retinal neovascularization and despite the fact that several VEGF targeting ocular drugs are available; the review examines the need for a cost economic alternative, thereby suggesting the role of AgNPs as an emerging economic ocular drug for retinal therapies. The current technologies available for the development of targeted and controlled release of drugs is being discussed and a model has been proposed for the amenable targeting mechanism, by which Poly gamma glutamic acid (PGA) capsulated AgNPs conjugated to cyclic RGD peptides carry out a sustained controlled release specifically targeting the neovascularization cells and induce apoptosis unaffecting the normal retinal cells. These constructs consequently affirm the futuristic application of silver nanoparticles as a boon to ocular therapies. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  10. A clinical approach to the diagnosis of retinal vasculitis.

    PubMed

    El-Asrar, Ahmed M Abu; Herbort, Carl P; Tabbara, Khalid F

    2010-04-01

    Retinal vasculitis is a sight-threatening inflammatory eye condition that involves the retinal vessels. Detection of retinal vasculitis is made clinically, and is confirmed with the help of fundus fluorescein angiography. Active vascular disease is characterized by exudates around retinal vessels resulting in white sheathing or cuffing of the affected vessels. In this review, a practical approach to the diagnosis of retinal vasculitis is discussed based on ophthalmoscopic and fundus fluorescein angiographic findings.

  11. Retinoids for Treatment of Retinal Diseases

    PubMed Central

    Palczewski, Krzysztof

    2010-01-01

    Knowledge about retinal photoreceptor signal transduction and the visual cycle required for normal eyesight has expanded exponentially over the past decade. Substantial progress in human genetics has allowed identification of candidate genes and complex networks underlying inherited retinal diseases. Natural mutations in animal models that mimic human diseases have been characterized and advanced genetic manipulation now permits generation of small mammalian models of human retinal diseases. Pharmacological repair of defective visual processes in animal models not only validates their involvement in vision but also provides great promise for developing improved therapies for the millions that are progressing towards blindness or are almost completely robbed of eyesight. PMID:20435355

  12. Retinal detachment associated with traumatic chorioretinal rupture.

    PubMed

    Papakostas, Thanos D; Yonekawa, Yoshihiro; Wu, David; Miller, John B; Veldman, Peter B; Chee, Yewlin E; Husain, Deeba; Eliott, Dean

    2014-01-01

    Traumatic chorioretinal rupture, also known as sclopetaria, is a full-thickness break of the choroid and retina caused by a high-velocity projectile striking or passing adjacent to, but not penetrating, the globe. Previous reports have emphasized that retinal detachment seldom occurs, and observation alone has been the recommended management strategy. However, the authors present herein a series of consecutive patients with retinal detachment associated with sclopetaria and provide a literature review of the topic. They recommend that patients with traumatic chorioretinal rupture be monitored closely for the development of retinal detachment during the first few weeks after the injury. Copyright 2014, SLACK Incorporated.

  13. Surgical treatment of central retinal vein occlusion.

    PubMed

    Berker, Nilufer; Batman, Cosar

    2008-05-01

    The treatment of central retinal vein occlusion (CRVO) is still a subject of debate. Medical therapy efforts, as well as retinal laser photocoagulation, have mostly dealt with management of the sequelae of CRVO, and have shown limited success in improving visual acuity. The unsatisfactory results of such therapeutic efforts led to the development of new treatment strategies focused on the surgical treatment of the occluded retinal vein. The purpose of this review is to summarize the outcomes of commonly reported surgical treatment strategies and to review different opinions on the various surgical approaches to the treatment of CRVO.

  14. Electrical properties of retinal-electrode interface.

    PubMed

    Shah, Samip; Hines, Amy; Zhou, David; Greenberg, Robert J; Humayun, Mark S; Weiland, James D

    2007-03-01

    A critical element of a retinal prosthesis is the stimulating electrode array, which is placed in close proximity to the retina. It is via this retinal-electrode interface that a retinal prosthesis electrically stimulates nerve cells to produce the perception of light. The impedance load seen by the current driver consists of the tissue resistance and the complex electrode impedance. The results in this paper show that the tissue resistance of the retina is significantly greater than that of the vitreous humor in the eye. Circuit models of the electrode-retina interface are used to parameterize the different contributors to the overall impedance.

  15. Roller coaster-associated retinal detachments.

    PubMed

    Shaikh, Saad

    2011-01-01

    The purpose of this study was to report two cases of rhegmatogenous retinal detachment noted immediately after roller coaster riding in an at-risk population. In separate incidents, a 35-year-old woman and a 45-year-old woman, both significantly myopic, presented with visual symptoms after riding roller coasters. Both patients were found to have acute rhegmatogenous retinal detachments associated with myopic degenerative changes. The pathology supported an acute, traumatic etiology for the detachments. Roller coaster riding should be considered an adjunct risk factor for retinal detachment in predisposed patients.

  16. Retinal prostheses: clinical results and future challenges.

    PubMed

    Picaud, Serge; Sahel, José-Alain

    2014-03-01

    Retinal prostheses aim at restoring visual perception in blind patients affected by retinal diseases leading to the loss of photoreceptors, such as age-related macular degeneration or retinitis pigmentosa. Recent clinical trials have demonstrated the feasibility of this approach for restoring useful vision. Despite a limited number of electrodes (60), and therefore of pixels, some patients were able to read words and to recognize high-contrast objects. Face recognition and independent locomotion in unknown urban environments imply technological breakthroughs to increase the number and density of electrodes. This review presents recent clinical results and discusses future solutions to answer the major technological challenges. Copyright © 2014. Published by Elsevier SAS.

  17. Smart image processing system for retinal prosthesis.

    PubMed

    Weiland, James D; Parikh, Neha; Pradeep, Vivek; Medioni, Gerard

    2012-01-01

    Retinal prostheses for the blind have demonstrated the ability to provide the sensation of light in otherwise blind individuals. However, visual task performance in these patients remains poor relative to someone with normal vision. Computer vision algorithms for navigation and object detection were evaluated for their ability to improve task performance. Blind subjects navigating a mobility course had fewer collisions when using a wearable camera system that guided them on a safe path. Subjects using a retinal prosthesis simulator could locate objects more quickly when an object detection algorithm assisted them. Computer vision algorithms can assist retinal prosthesis patients and low-vision patients in general.

  18. Accommodative loss after retinal cryotherapy.

    PubMed

    Uno, Tsuyoshi; Okuyama, Michiko; Tanabe, Tatsuro; Kawamura, Ryosuke; Ideta, Hidenao

    2009-01-01

    To investigate the effects of peripheral retinal cryotherapy on accommodative amplitude in patients with retinal lattice degeneration. Prospective, observational case series. We studied 92 eyes in 69 patients (age range, 13 to 79 years) treated with cryotherapy for lattice degeneration between December 2001 and September 2004. Pretreatment and posttreatment accommodative amplitudes were measured. Acute accommodative loss was calculated from the difference between accommodative amplitudes before treatment and one week after treatment. We investigated the time course of accommodative amplitudes, acute accommodative loss in different age groups and in pretreatment accommodative amplitude groups, the influence of cryotherapy numbers on accommodative amplitude, and the influence of cryotherapy sites on accommodative amplitude. No significant difference was noted between pretreatment and posttreatment accommodative amplitudes in the overall subject cohort. Dividing subjects by age revealed significant decreases in accommodative amplitude only among patients in their 10s and 20s at one and three weeks after treatment. Accommodative amplitude was lowest among those in their 10s, followed by that among those in their 20s (P < .01). Accommodative amplitudes recovered to pretreatment level by six weeks. Acute accommodative loss was greatest in those in their 10s compared with other age groups (P < .01). A significant correlation was observed between acute accommodative loss and cryotherapy numbers (P = .03; r = 0.41). The decrease in accommodative amplitude was greatest at one week after treatment and recovered to pretreatment levels after six weeks. Accommodative amplitude showed the greatest decrease after cryotherapy among patients in their 10s and 20s. A decrease in accommodative amplitude was observed with increased numbers of cryotherapy spots administered.

  19. Retinal pigment epithelium lipofuscin proteomics.

    PubMed

    Ng, Kwok-Peng; Gugiu, Bogdan; Renganathan, Kutralanathan; Davies, Matthew W; Gu, Xiaorong; Crabb, John S; Kim, So Ra; Rózanowska, Malgorzata B; Bonilha, Vera L; Rayborn, Mary E; Salomon, Robert G; Sparrow, Janet R; Boulton, Michael E; Hollyfield, Joe G; Crabb, John W

    2008-07-01

    Lipofuscin accumulates with age in the retinal pigment epithelium (RPE) in discrete granular organelles and may contribute to age-related macular degeneration. Because previous studies suggest that lipofuscin contains protein that may impact pathogenic mechanisms, we pursued proteomics analysis of lipofuscin. The composition of RPE lipofuscin and its mechanisms of pathogenesis are poorly understood in part because of the heterogeneity of isolated preparations. We purified RPE lipofuscin granules by treatment with proteinase K or SDS and showed by light, confocal, and transmission electron microscopy that the purified granules are free of extragranular material and associated membranes. Crude and purified lipofuscin preparations were quantitatively compared by (i) LC MS/MS proteomics analyses, (ii) immunoanalyses of oxidative protein modifications, (iii) amino acid analysis, (iv) HPLC of bisretinoids, and (v) assaying phototoxicity to RPE cells. From crude lipofuscin preparations 186 proteins were identified, many of which appeared to be modified. In contrast, very little protein ( approximately 2% (w/w) by amino acid analysis) and no identifiable protein were found in the purified granules, which retained full phototoxicity to cultured RPE cells. Our analyses showed that granules in purified and crude lipofuscin preparations exhibit no statistically significant differences in diameter or circularity or in the content of the bisretinoids A2E, isoA2E, and all-trans-retinal dimer-phosphatidylethanolamine. The finding that the purified granules contain minimal protein yet retain phototoxic activity suggests that RPE lipofuscin pathogenesis is largely independent of associated protein. The purified granules also exhibited oxidative protein modifications, including nitrotyrosine generated from reactive nitrogen oxide species and carboxyethylpyrrole and iso[4]levuglandin E(2) adducts generated from reactive lipid fragments. This finding is consistent with previous studies

  20. Interfacial photochemistry of retinal proteins

    NASA Astrophysics Data System (ADS)

    Hong, Felix T.

    1999-09-01

    Retinal proteins are membrane-bound protein pigments that contain vitamin A aldehyde (retinal) as the chromophore. They include the visual pigment rhodopsin and four additional ones in the plasma membrane of Halobacterium salinarium (formerly Halobacterium halobium). These proteins maintain a fixed and asymmetric orientation in the membranes, and respond to a light stimulus by generating vectorial charge movement, which can be detected as an electric potential across the membrane or an electric current through the membrane. These phenomena are collectively called the photoelectric effects, which defy a rigorous quantitative treatment by means of either conventional (solution phase) photochemistry or conventional electrophysiology. As an alternative to the mainstream approach, we utilize the analytic tools of electrochemical surface science and electrophysiology to analyze two molecular models of light-induced charge separation and recombination. Being tutorial in nature, this article demands no prior knowledge about the subject. A parsimonious equivalent circuit model is developed. Data obtained from reconstituted bacteriorhodopsin membranes are used to validate the theoretical model and the analytical approach. Data generated and used by critics to refute our approach is shown to actually support it. The present analysis is sufficiently general to be applicable to other pigment-containing membranes, such as the visual photoreceptor membrane and the chlorophyll-based photosynthetic membranes. It provides a coherent description of a wide range of light-induced phenomena associated with various pigment-containing membranes. In contrast, the mainstream approach has been plagued with self-contradictions and paradoxes. Last, but not least, the alternative bioelectrochemical approach also exhibits a predictive power that has hitherto been generally lacking. Comparison of the photoelectric effects is made with regard to bacteriorhodopsin, rhodopsin, and the chlorophyll

  1. Retinal Detachment After Subretinal Stem Cell Transplantation.

    PubMed

    Leung, Ella H; Flynn, Harry W; Albini, Thomas A; Medina, Carlos A

    2016-06-01

    A 60-year-old man with Stargardt's macular dystrophy and visual acuity of 20/400 in the right eye and 20/60 in the left eye underwent a subretinal injection of autologous bone marrow-derived stem cells in the right eye. The patient developed a retinal detachment in the right eye 2 months later that was initially treated with a scleral buckle, but the patient subsequently developed a recurrent retinal detachment with proliferative vitreoretinopathy. A pars plana vitrectomy, membrane peel, fluid-air exchange, endolaser, and silicone oil injection were then performed. The retina remained attached 5 months later, with improvement in visual acuity from hand motions to 20/300 post-vitrectomy. Retinal detachment may occur after subretinal injection of stem cells. Proliferative vitreoretinopathy may develop in these patients, but the visual acuity may return to baseline after retinal reattachment. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:600-601.]. Copyright 2016, SLACK Incorporated.

  2. Retinal fractals and acute lacunar stroke.

    PubMed

    Cheung, Ning; Liew, Gerald; Lindley, Richard I; Liu, Erica Y; Wang, Jie Jin; Hand, Peter; Baker, Michelle; Mitchell, Paul; Wong, Tien Y

    2010-07-01

    This study aimed to determine whether retinal fractal dimension, a quantitative measure of microvascular branching complexity and density, is associated with lacunar stroke. A total of 392 patients presenting with acute ischemic stroke had retinal fractal dimension measured from digital photographs, and lacunar infarct ascertained from brain imaging. After adjusting for age, gender, and vascular risk factors, higher retinal fractal dimension (highest vs lowest quartile and per standard deviation increase) was independently and positively associated with lacunar stroke (odds ratio [OR], 4.27; 95% confidence interval [CI], 1.49-12.17 and OR, 1.85; 95% CI, 1.20-2.84, respectively). Increased retinal microvascular complexity and density is associated with lacunar stroke.

  3. Imaging retinal mosaics in the living eye

    PubMed Central

    Rossi, E A; Chung, M; Dubra, A; Hunter, J J; Merigan, W H; Williams, D R

    2011-01-01

    Adaptive optics imaging of cone photoreceptors has provided unique insight into the structure and function of the human visual system and has become an important tool for both basic scientists and clinicians. Recent advances in adaptive optics retinal imaging instrumentation and methodology have allowed us to expand beyond cone imaging. Multi-wavelength and fluorescence imaging methods with adaptive optics have allowed multiple retinal cell types to be imaged simultaneously. These new methods have recently revealed rod photoreceptors, retinal pigment epithelium (RPE) cells, and the smallest retinal blood vessels. Fluorescence imaging coupled with adaptive optics has been used to examine ganglion cells in living primates. Two-photon imaging combined with adaptive optics can evaluate photoreceptor function non-invasively in the living primate retina. PMID:21390064

  4. Imaging retinal mosaics in the living eye.

    PubMed

    Rossi, E A; Chung, M; Dubra, A; Hunter, J J; Merigan, W H; Williams, D R

    2011-03-01

    Adaptive optics imaging of cone photoreceptors has provided unique insight into the structure and function of the human visual system and has become an important tool for both basic scientists and clinicians. Recent advances in adaptive optics retinal imaging instrumentation and methodology have allowed us to expand beyond cone imaging. Multi-wavelength and fluorescence imaging methods with adaptive optics have allowed multiple retinal cell types to be imaged simultaneously. These new methods have recently revealed rod photoreceptors, retinal pigment epithelium (RPE) cells, and the smallest retinal blood vessels. Fluorescence imaging coupled with adaptive optics has been used to examine ganglion cells in living primates. Two-photon imaging combined with adaptive optics can evaluate photoreceptor function non-invasively in the living primate retina.

  5. Emerging therapies for inherited retinal degeneration.

    PubMed

    Scholl, Hendrik P N; Strauss, Rupert W; Singh, Mandeep S; Dalkara, Deniz; Roska, Botond; Picaud, Serge; Sahel, José-Alain

    2016-12-07

    Inherited retinal degenerative diseases, a genetically and phenotypically heterogeneous group of disorders, affect the function of photoreceptor cells and are among the leading causes of blindness. Recent advances in molecular genetics and cell biology are elucidating the pathophysiological mechanisms underlying these disorders and are helping to identify new therapeutic approaches, such as gene therapy, stem cell therapy, and optogenetics. Several of these approaches have entered the clinical phase of development. Artificial replacement of dying photoreceptor cells using retinal prostheses has received regulatory approval. Precise retinal imaging and testing of visual function are facilitating more efficient clinical trial design. In individual patients, disease stage will determine whether the therapeutic strategy should comprise photoreceptor cell rescue to delay or arrest vision loss or retinal replacement for vision restoration. Copyright © 2016, American Association for the Advancement of Science.

  6. [Retinal vein occlusion in a young patient].

    PubMed

    Zemba, Mihail; Ochinciuc, Uliana; Sarbu, Laura; Avram, Corina; Camburu, Raluca; Stamate, Alina

    2013-01-01

    We present a case report of a 27 years old pacient with central retinal vein occlussion and macular edema. The pacient has a significant reduction of the macular aedema with complete recovery of vision after the treatment.

  7. [Intraocular hypertension after retinal detachment surgery].

    PubMed

    Muşat, O; Cristescu, R; Coman, Corina; Asandi, R

    2012-01-01

    This papers presents a case of a patient with retinal detachment, 3 days ago operated (posterior vitrectomy, internal tamponament with silicon oil 1000) who developed increased ocular pressure following silicon oil output in the anterior chamber.

  8. Screening Diabetic Retinopathy Through Color Retinal Images

    NASA Astrophysics Data System (ADS)

    Li, Qin; Jin, Xue-Min; Gao, Quan-Xue; You, Jane; Bhattacharya, Prabir

    Diabetic Retinopathy (DR) is a common complication of diabetes that damages the eye's retina. Recognition DR as early as possible is very important to protect patients' vision. We propose a method for screening DR and distin-guishing Prolifetive Diabetic Retinopathy (PDR) from Non-Prolifetive Retino-pathy (NPDR) automatatically through color retinal images. This method evaluates the severity of DR by analyzing the appearnce of bright lesions and retinal vessel patterns. The bright lesions are extracted through morphlogical re-consturction. After that, the retinal vessels are automatically extracted using multiscale matched filters. Then the vessel patterns are analyzed by extracting the vessel net density. The experimental results domonstrate that it is a effective solution to screen DR and distinguish PDR from NPDR by only using color retinal images.

  9. Retinal Detachment: Torn or Detached Retina Symptoms

    MedlinePlus

    ... should call your ophthalmologist right away. See a simulation of what vision with a torn or detached ... Feb 20, 2018 Gene Therapy May Be a Game-Changer for People With Inherited Retinal Disease Dec ...

  10. Programming Retinal Stem Cells into Cone Photoreceptors

    DTIC Science & Technology

    2015-12-01

    to program human stem cells directly into cones. Using RNA - seq , we identified several genes that are upregulated in advance of the earliest...reverse vision loss. 15. SUBJECT TERMS Cone photoreceptor, retina, retinal stem cell, Otx2, Onecut1, Blimp1, RNA - seq ., transcription factors, and...1 Keywords: 1. Cone photoreceptor 2. Retina 3. Retinal stem cell 4. Otx2 5. Onecut1 6. Blimp1 7. RNA - seq . 8. Transcription factors 9

  11. Role of Hydrogen Sulfide in Retinal Diseases

    PubMed Central

    Du, Jiantong; Jin, Hongfang; Yang, Liu

    2017-01-01

    As the third gasotransmitter, hydrogen sulfide (H2S) plays a crucial role in the physiology and pathophysiology of many systems in the body, such as the nervous, cardiovascular, respiratory, and gastrointestinal systems. The mechanisms for its effects, including inhibiting ischemic injury, reducing oxidative stress damage, regulating apoptosis, and reducing the inflammation reaction in different systems, have not been fully understood. Recently, H2S and its endogenous synthesis pathway were found in the mammalian retina. This review describes the production and the metabolism of H2S and the evidence of a role of H2S in the retina physiology and in the different retinal diseases, including retinal degenerative diseases and vascular diseases. In the retina, H2S is generated in the presence of cystathionine-β-synthase, cystathionine-γ-lyase, and 3-mercaptopyruvate sulfurtransferase from L-cysteine. The role of endogenous H2S and its physiologic effect in the retina are still elusive. However, strong evidence shows that retina-derived H2S might play protective or deleterious role in the pathogenesis of retinal diseases. For example, by regulating Ca2+ influx, H2S can protect retinal neurons against light-induced degeneration. H2S preconditioning can mediate the anti-apoptotic effect of retinal ganglion cells in retinal ischemia/reperfusion injury. Treatment with H2S in rats relieves diabetic retinopathy by suppressing oxidative stress and reducing inflammation. Further studies would greatly improve our understanding of the pathophysiologic mechanisms responsible for retinal diseases and the potential for the H2S-related therapy of the retinal diseases as well. PMID:28900398

  12. Safety of iPhone retinal photography.

    PubMed

    Hong, Sheng Chiong; Wynn-Williams, Giles; Wilson, Graham

    2017-04-01

    With the advancement in mobile technology, smartphone retinal photography is becoming a popular practice. However, there is limited information about the safety of the latest smartphones used for retinal photography. This study aims to determine the photobiological risk of iPhone 6 and iPhone 6 plus when used in conjunction with a 20Diopter condensing lens for retinal photography. iPhone 6 and iPhone 6 plus (Apple, Cupertino, CA) were used in this study. The geometrical setup of the study was similar to the indirect ophthalmoscopy technique. The phone was set up at one end of the bench with its flash turned on at maximal brightness; a 20 Dioptre lens was placed 15 cm away from the phone. The light that passes through the lens was measured with a spectroradiometer and an illuminance probe at the other end to determine the spectral profile, spatial irradiance, radiant power emitted by the phone's flash. Trigonometric and lens formula were applied to determine the field of view and retinal surface in order to determine the weighted retinal irradiance and weighted retinal radiant exposure. Taking ocular transmission and the distribution of the beam's spatial irradiance into account, the weighted retinal irradiance is 1.40 mW/cm 2 and the weighted retinal radiant exposure is 56.25 mJ/cm 2 . The peak weighted foveal irradiance is 1.61 mW/cm 2 . Our study concluded that the photobiological risk posed by iPhone 6 indirect ophthalmoscopy was at least 1 order of magnitude below the safety limits set by the ISO15004-2.2.

  13. Role of Hydrogen Sulfide in Retinal Diseases.

    PubMed

    Du, Jiantong; Jin, Hongfang; Yang, Liu

    2017-01-01

    As the third gasotransmitter, hydrogen sulfide (H 2 S) plays a crucial role in the physiology and pathophysiology of many systems in the body, such as the nervous, cardiovascular, respiratory, and gastrointestinal systems. The mechanisms for its effects, including inhibiting ischemic injury, reducing oxidative stress damage, regulating apoptosis, and reducing the inflammation reaction in different systems, have not been fully understood. Recently, H 2 S and its endogenous synthesis pathway were found in the mammalian retina. This review describes the production and the metabolism of H 2 S and the evidence of a role of H 2 S in the retina physiology and in the different retinal diseases, including retinal degenerative diseases and vascular diseases. In the retina, H 2 S is generated in the presence of cystathionine-β-synthase, cystathionine-γ-lyase, and 3-mercaptopyruvate sulfurtransferase from L-cysteine. The role of endogenous H 2 S and its physiologic effect in the retina are still elusive. However, strong evidence shows that retina-derived H 2 S might play protective or deleterious role in the pathogenesis of retinal diseases. For example, by regulating Ca 2+ influx, H 2 S can protect retinal neurons against light-induced degeneration. H 2 S preconditioning can mediate the anti-apoptotic effect of retinal ganglion cells in retinal ischemia/reperfusion injury. Treatment with H 2 S in rats relieves diabetic retinopathy by suppressing oxidative stress and reducing inflammation. Further studies would greatly improve our understanding of the pathophysiologic mechanisms responsible for retinal diseases and the potential for the H 2 S-related therapy of the retinal diseases as well.

  14. Retinal remodeling triggered by photoreceptor degenerations.

    PubMed

    Jones, Bryan W; Watt, Carl B; Frederick, Jeanne M; Baehr, Wolfgang; Chen, Ching-Kang; Levine, Edward M; Milam, Ann H; Lavail, Matthew M; Marc, Robert E

    2003-09-08

    Many photoreceptor degenerations initially affect rods, secondarily leading to cone death. It has long been assumed that the surviving neural retina is largely resistant to this sensory deafferentation. New evidence from fast retinal degenerations reveals that subtle plasticities in neuronal form and connectivity emerge early in disease. By screening mature natural, transgenic, and knockout retinal degeneration models with computational molecular phenotyping, we have found an extended late phase of negative remodeling that radically changes retinal structure. Three major transformations emerge: 1) Müller cell hypertrophy and elaboration of a distal glial seal between retina and the choroid/retinal pigmented epithelium; 2) apparent neuronal migration along glial surfaces to ectopic sites; and 3) rewiring through evolution of complex neurite fascicles, new synaptic foci in the remnant inner nuclear layer, and new connections throughout the retina. Although some neurons die, survivors express molecular signatures characteristic of normal bipolar, amacrine, and ganglion cells. Remodeling in human and rodent retinas is independent of the initial molecular targets of retinal degenerations, including defects in the retinal pigmented epithelium, rhodopsin, or downstream phototransduction elements. Although remodeling may constrain therapeutic intervals for molecular, cellular, or bionic rescue, it suggests that the neural retina may be more plastic than previously believed. Copyright 2003 Wiley-Liss, Inc.

  15. Complete Blood Count and Retinal Vessel Diameters

    PubMed Central

    Klein, Barbara E. K.; Klein, Ronald; Myers, Chelsea E.; Lee, Kristine E.

    2010-01-01

    Objective To examine the cross-sectional associations of components of the complete blood count with retinal vessel diameters. Methods The data are from the 1988–1990 baseline examination of the Beaver Dam Eye Study cohort (n=4730). Blood pressure was measured, a medical history including questions on smoking was obtained, and fundus photographs centered on the optic disc were taken and digitized. Retinal arteriole and venule diameters were measured using computer-assisted software. The central retinal arteriole equivalent (CRAE) and central retinal venule equivalent (CRVE) were computed. A complete blood count was done. Results In age and sex adjusted analyses, red blood cell count (RBC), hemoglobin, hematocrit, and white blood cell (WBC) count were all statistically significantly associated with CRVE and CRAE, while platelet count was associated only with CRVE. These relationships persisted in more fully adjusted models, except platelet count became statistically significantly associated with both CRAE and CRVE. Conclusions Blood components as measured in a complete blood count are significant correlates of retinal vessel diameters and should be considered in analyses where retinal blood vessel diameters are outcomes. PMID:21482874

  16. Fractal pattern formation in human retinal vessels

    NASA Astrophysics Data System (ADS)

    Family, Fereydoon; Masters, Barry R.; Platt, Daniel E.

    1989-09-01

    The mechanism for the formation of retinal vessel patterns in the developing human eye is an unresolved question of considerable importance. The current hypothesis is based on the existence of a variable oxygen gradient across the developing photoreceptors which stimulates the release of angiogenic factors which diffuse in the plane of the retina and result in the growth of retinal vessels. This implies that the limiting step in the formation of retinal blood vessels is a diffusion process. To test this hypothesis we have performed a fractal analysis of the human retinal vessels using two different methods. Within the limited range of length scales available in the red-free fundus photographs, we find that the human retinal blood vessels have a self-similar structure with a fractal dimension D ≈ 1.7. Since this value of D is the same as the value found for a diffusion limited growth process, our result supports the hypothesis that diffusion is the fundamental process in the formation of human retinal vessel patterns.

  17. Retinal vascular fractals and cognitive impairment.

    PubMed

    Ong, Yi-Ting; Hilal, Saima; Cheung, Carol Yim-Lui; Xu, Xin; Chen, Christopher; Venketasubramanian, Narayanaswamy; Wong, Tien Yin; Ikram, Mohammad Kamran

    2014-05-01

    Retinal microvascular network changes have been found in patients with age-related brain diseases such as stroke and dementia including Alzheimer's disease. We examine whether retinal microvascular network changes are also present in preclinical stages of dementia. This is a cross-sectional study of 300 Chinese participants (age: ≥60 years) from the ongoing Epidemiology of Dementia in Singapore study who underwent detailed clinical examinations including retinal photography, brain imaging and neuropsychological testing. Retinal vascular parameters were assessed from optic disc-centered photographs using a semiautomated program. A comprehensive neuropsychological battery was administered, and cognitive function was summarized as composite and domain-specific Z-scores. Cognitive impairment no dementia (CIND) and dementia were diagnosed according to standard diagnostic criteria. Among 268 eligible nondemented participants, 78 subjects were categorized as CIND-mild and 69 as CIND-moderate. In multivariable adjusted models, reduced retinal arteriolar and venular fractal dimensions were associated with an increased risk of CIND-mild and CIND-moderate. Reduced fractal dimensions were associated with poorer cognitive performance globally and in the specific domains of verbal memory, visuoconstruction and visuomotor speed. A sparser retinal microvascular network, represented by reduced arteriolar and venular fractal dimensions, was associated with cognitive impairment, suggesting that early microvascular damage may be present in preclinical stages of dementia.

  18. Somatostatin analogues as therapeutics in retinal disease.

    PubMed

    Vasilaki, Anna; Thermos, Kyriaki

    2009-06-01

    Despite the rapid development of new pharmacological and surgical modalities, the treatment of retinal disease all too often results in poor final visual acuity. The primary pathologic mechanism underlying suboptimal visual acuity following retinal disease is cell death. It is induced by a variety of stimuli including ischemia, inflammation, and oxidative stress. New neuroprotective strategies have recently being examined for the prevention of retinal cell death, yet there is still a need for pharmacological agents that are efficacious and lack adverse effects. These could possibly be employed alone or in combination with disease-specific treatments. The neuropeptide somatostatin and its sst(2) receptor selective analogues have been shown to inhibit the ischemia-induced neovascularization in models of retinal ischemia, and to protect from ischemia-induced cell death. The aim of this review is threefold: a) to address the functional role of somatostatin and its receptors in retinal circuitry, b) to present recent evidence supporting the neuroprotective role of somatostatin in experimental models of retinal disease and c) to present the clinical studies that have been performed to date and support the use of somatostatin and its analogues as therapeutics in ophthalmology.

  19. [Juxta-basal retinal dialysis near the ora serrata].

    PubMed

    Slezak, H; Arocker-Mettinger, E

    1989-09-01

    Retinal dialyses near the ora are large, crescent-shaped retinal defects immediately behind the ora serrata. It is assumed that they practically always occur without posterior vitreous detachment and spread within the vitreous base (intrabasal retinal dialysis). However, there are evidently exceptions to this rule: there may be posterior vitreous detachment with the posterior hyaloid membrane which encroach on the anterior margin of the retinal defect; the defect then spreads along the posterior margin of the vitreous base and is hence a juxtabasal retinal dialysis. While the ophthalmoscopic features of intrabasal and juxtabasal retinal dialysis near the ora serrata are always identical, there are distinct biomicroscopic differences between the two forms.

  20. [Ocular electrical stimulation: Therapeutic application and active retinal implants for hereditary retinal degenerations].

    PubMed

    Gekeler, F; Zrenner, E; Bartz-Schmidt, K U

    2015-09-01

    Electrical stimulation has a long history in ophthalmology. Subthreshold electrical stimulation can have beneficial therapeutic effects on hereditary degenerative retinal diseases. Suprathreshold stimulation is able to elicit visual perceptions and, if multielectrode fields are arranged as an array, usable pictures can be perceived by blind patients. This is a review article on the current situation and studies on therapeutic transcorneal electrical stimulation. Moreover, the challenges, surgical concepts and visual results of active retinal implants are discussed. This article gives an overview on transcorneal electrical stimulation and active retinal implants based on published results, with special emphasis on the clinical application. The results of initial controlled studies on therapeutic transcorneal electrical stimulation in hereditary retinal diseases were very promising. The largest controlled study so far in patients with retinitis pigmentosa (RP) has yielded many positive trends and some significant improvements in electrophysiological data. Currently, two retinal implants have regulatory approval, the Argus II retinal prosthesis system® (SecondSight®) and the Alpha-IMS© (Retina Implant AG). Both systems can be used to improve visual perception and under test conditions can achieve visual acuities of 0.02 and 0.04, respectively. In-depth analyses and follow-up studies in larger patient groups are currently planned to definitively clarify the potential of therapeutic transcorneal electrical stimulation in RP patients. The challenges of currently available active retinal implants are the technical biostability and the limited spatial resolution.

  1. Towards automatic detection of abnormal retinal capillaries in ultra-widefield-of-view retinal angiographic exams.

    PubMed

    Zutis, K; Trucco, E; Hubschman, J P; Reed, D; Shah, S; van Hemert, J

    2013-01-01

    Retinal capillary abnormalities include small, leaky, severely tortuous blood vessels that are associated with a variety of retinal pathologies. We present a prototype image-processing system for detecting abnormal retinal capillary regions in ultra-widefield-of-view (UWFOV) fluorescein angiography exams of the human retina. The algorithm takes as input an UWFOV FA frame and returns the candidate regions identified. An SVM classifier is trained on regions traced by expert ophthalmologists. Tests with a variety of feature sets indicate that edge features and allied properties differentiate best between normal and abnormal retinal capillary regions. Experiments with an initial set of images from patients showing branch retinal vein occlusion (BRVO) indicate promising area under the ROC curve of 0.950 and a weighted Cohen's Kappa value of 0.822.

  2. Giant Retinal Tear With Retinal Detachment in Regressed Aggressive Posterior Retinopathy of Prematurity Treated by Laser.

    PubMed

    Chandra, Parijat; Tewari, Ruchir; Salunkhe, Nitesh; Kumawat, Devesh; Kumar, Vinod

    2017-06-29

    Rhegmatogenous retinal detachment after successfully regressed retinopathy of prematurity is a rare occurrence. Late onset rhegmatogenous retinal detachment has been reported infrequently. The authors report a case of aggressive posterior retinopathy of prematurity that underwent uneventful regression after laser photocoagulation and later developed an inoperable closed funnel retinal detachment due to a giant retinal tear. This case represents the earliest development of such complications in regressed aggressive posterior retinopathy of prematurity treated by laser. Development of a giant retinal tear has also not been previously reported after laser treatment. This case highlights that successful regression of severe retinopathy of prematurity does not safeguard against future complications and requires frequent long-term follow-up. [J Pediatr Ophthalmol Strabismus. 2017;54:e34-e36.]. Copyright 2017, SLACK Incorporated.

  3. Lattice degeneration of the retina and retinal detachment.

    PubMed

    Semes, L P

    1992-01-01

    Lattice retinal degeneration is considered the most significant peripheral retinal disorder potentially predisposing to retinal breaks and retinal detachment. Lattice degeneration affects the vitreous and inner retinal layers with secondary changes as deep as the retinal pigment epithelium and perhaps the choriocapillaris. Variations in clinical appearance are the rule; geographically, lattice lesions favor the vertical meridians between the equator and the ora serrata. Lattice degeneration begins early in life and has been reported in sequential generations of the same family. Along with its customary bilateral occurrence, lattice shares other characteristics of a dystrophy. The association between the vitreous and retina in lattice lesions may be responsible for the majority of lattice-induced retinal detachments. The tumultuous event of posterior vitreous separation in the presence of abnormally strong vitreoretinal adherence is the trigger for a retinal tear that, in turn, may lead to retinal detachment. Although retinal holes in young patients with lattice degeneration may play a role in the evolution of retinal detachment, the clinical course of lattice degeneration seems to be one of dormancy rather than of progressive change. This discussion outlines the pathophysiology of lattice retinal degeneration and the relationship of pathophysiology to clinical presentation. The epidemiology of lattice degeneration is summarized, as are the possible precursors to retinal detachment. A clinical characterization of the natural history of lattice degeneration is offered, and interventions for complications are described. To conclude, management strategies from a primary-care standpoint are reviewed.

  4. Long-term safety of human retinal progenitor cell transplantation in retinitis pigmentosa patients.

    PubMed

    Liu, Yong; Chen, Shao Jun; Li, Shi Ying; Qu, Ling Hui; Meng, Xiao Hong; Wang, Yi; Xu, Hai Wei; Liang, Zhi Qing; Yin, Zheng Qin

    2017-09-29

    Retinitis pigmentosa is a common genetic disease that causes retinal degeneration and blindness for which there is currently no curable treatment available. Vision preservation was observed in retinitis pigmentosa animal models after retinal stem cell transplantation. However, long-term safety studies and visual assessment have not been thoroughly tested in retinitis pigmentosa patients. In our pre-clinical study, purified human fetal-derived retinal progenitor cells (RPCs) were transplanted into the diseased retina of Royal College of Surgeons (RCS) rats, a model of retinal degeneration. Based on these results, we conducted a phase I clinical trial to establish the safety and tolerability of transplantation of RPCs in eight patients with advanced retinitis pigmentosa. Patients were studied for 24 months. After RPC transplantation in RCS rats, we observed moderate recovery of vision and maintenance of the outer nuclear layer thickness. Most importantly, we did not find tumor formation or immune rejection. In the retinis pigmentosa patients given RPC injections, we also did not observe immunological rejection or tumorigenesis when immunosuppressive agents were not administered. We observed a significant improvement in visual acuity (P < 0.05) in five patients and an increase in retinal sensitivity of pupillary responses in three of the eight patients between 2 and 6 months after the transplant, but this improvement did not appear by 12 months. Our study for the first time confirmed the long-term safety and feasibility of vision repair by stem cell therapy in patients blinded by retinitis pigmentosa. WHO Trial Registration, ChiCTR-TNRC-08000193 . Retrospectively registered on 5 December 2008.

  5. Toward high-resolution optoelectronic retinal prosthesis

    NASA Astrophysics Data System (ADS)

    Palanker, Daniel; Huie, Philip; Vankov, Alexander; Asher, Alon; Baccus, Steven

    2005-04-01

    It has been already demonstrated that electrical stimulation of retina can produce visual percepts in blind patients suffering from macular degeneration and retinitis pigmentosa. Current retinal implants provide very low resolution (just a few electrodes), while several thousand pixels are required for functional restoration of sight. We present a design of the optoelectronic retinal prosthetic system that can activate a retinal stimulating array with pixel density up to 2,500 pix/mm2 (geometrically corresponding to a visual acuity of 20/80), and allows for natural eye scanning rather than scanning with a head-mounted camera. The system operates similarly to "virtual reality" imaging devices used in military and medical applications. An image from a video camera is projected by a goggle-mounted infrared LED-LCD display onto the retina, activating an array of powered photodiodes in the retinal implant. Such a system provides a broad field of vision by allowing for natural eye scanning. The goggles are transparent to visible light, thus allowing for simultaneous utilization of remaining natural vision along with prosthetic stimulation. Optical control of the implant allows for simple adjustment of image processing algorithms and for learning. A major prerequisite for high resolution stimulation is the proximity of neural cells to the stimulation sites. This can be achieved with sub-retinal implants constructed in a manner that directs migration of retinal cells to target areas. Two basic implant geometries are described: perforated membranes and protruding electrode arrays. Possibility of the tactile neural stimulation is also examined.

  6. Prenylation defects in inherited retinal diseases.

    PubMed

    Roosing, Susanne; Collin, Rob W J; den Hollander, Anneke I; Cremers, Frans P M; Siemiatkowska, Anna M

    2014-03-01

    Many proteins depend on post-translational prenylation for a correct subcellular localisation and membrane anchoring. This involves the covalent attachment of farnesyl or geranylgeranyl residues to cysteines residing in consensus motifs at the C-terminal parts of proteins. Retinal photoreceptor cells are highly compartmentalised and membranous structures, and therefore it can be expected that the proper function of many retinal proteins depends on prenylation, which has been proven for several proteins that are absent or defective in different inherited retinal diseases (IRDs). These include proteins involved in the phototransduction cascade, such as GRK1, the phosphodiesterase 6 subunits and the transducin γ subunit, or proteins involved in transport processes, such as RAB28 and retinitis pigmentosa GTPase regulator (RPGR). In addition, there is another class of general prenylation defects due to mutations in proteins such as AIPL1, PDE6D and rab escort protein-1 (REP-1), which can act as chaperones for subsets of prenylated retinal proteins that are associated with IRDs. REP-1 also is a key accessory protein of geranylgeranyltransferase II, an enzyme involved in the geranylgeranylation of almost all members of a large family of Rab GTPases. Finally, mutations in the mevalonate kinase (MVK) gene, which were known to be principally associated with mevalonic aciduria, were recently associated with non-syndromic retinitis pigmentosa. We hypothesise that MVK deficiency results in a depletion of prenyl moieties that affects the prenylation of many proteins synthesised specifically in the retina, including Rabs. In this review, we discuss the entire spectrum of prenylation defects underlying progressive degeneration of photoreceptors, the retinal pigment epithelium and the choroid.

  7. Interventions for asymptomatic retinal breaks and lattice degeneration for preventing retinal detachment

    PubMed Central

    Wilkinson, Charles P

    2015-01-01

    Background Asymptomatic retinal breaks and lattice degeneration are visible lesions that are risk factors for later retinal detachment. Retinal detachments occur when fluid in the vitreous cavity passes through tears or holes in the retina and separates the retina from the underlying retinal pigment epithelium. Creation of an adhesion surrounding retinal breaks and lattice degeneration, with laser photocoagulation or cryotherapy, has been recommended as an effective means of preventing retinal detachment. This therapy is of value in the management of retinal tears associated with the symptoms of flashes and floaters and persistent vitreous traction upon the retina in the region of the retinal break, because such symptomatic retinal tears are associated with a high rate of progression to retinal detachment. Retinal tears and holes unassociated with acute symptoms and lattice degeneration are significantly less likely to be the sites of retinal breaks that are responsible for later retinal detachment. Nevertheless, treatment of these lesions frequently is recommended, in spite of the fact that the effectiveness of this therapy is unproven. Objectives The objective of this review was to assess the effectiveness and safety of techniques used to treat asymptomatic retinal breaks and lattice degeneration for the prevention of retinal detachment. Search methods We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 2), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to February 2014), EMBASE (January 1980 to February 2014), PubMed (January 1948 to February 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in

  8. Interventions for asymptomatic retinal breaks and lattice degeneration for preventing retinal detachment.

    PubMed

    Wilkinson, Charles P

    2014-09-05

    Asymptomatic retinal breaks and lattice degeneration are visible lesions that are risk factors for later retinal detachment. Retinal detachments occur when fluid in the vitreous cavity passes through tears or holes in the retina and separates the retina from the underlying retinal pigment epithelium. Creation of an adhesion surrounding retinal breaks and lattice degeneration, with laser photocoagulation or cryotherapy, has been recommended as an effective means of preventing retinal detachment. This therapy is of value in the management of retinal tears associated with the symptoms of flashes and floaters and persistent vitreous traction upon the retina in the region of the retinal break, because such symptomatic retinal tears are associated with a high rate of progression to retinal detachment. Retinal tears and holes unassociated with acute symptoms and lattice degeneration are significantly less likely to be the sites of retinal breaks that are responsible for later retinal detachment. Nevertheless, treatment of these lesions frequently is recommended, in spite of the fact that the effectiveness of this therapy is unproven. The objective of this review was to assess the effectiveness and safety of techniques used to treat asymptomatic retinal breaks and lattice degeneration for the prevention of retinal detachment. We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 2), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to February 2014), EMBASE (January 1980 to February 2014), PubMed (January 1948 to February 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials

  9. Genetics Home Reference: neuropathy, ataxia, and retinitis pigmentosa

    MedlinePlus

    ... Share: Email Facebook Twitter Home Health Conditions NARP Neuropathy, ataxia, and retinitis pigmentosa Printable PDF Open All ... Javascript to view the expand/collapse boxes. Description Neuropathy, ataxia, and retinitis pigmentosa ( NARP ) is a condition ...

  10. Retinal Arteriovenous Malformation Assessment Using Swept-Source OCT Angiography.

    PubMed

    Chawla, Rohan; Pujari, Amar; Mittal, Kanhaiya; Rakheja, Vaishali; Markan, Ashish

    2018-03-01

    Swept-source optical coherence tomography angiography (SS-OCTA) is a promising new imaging modality for assessing retinal and choroidal vasculature. Faster scanning speed, large number of A-scan acquisition, and enhanced depth penetration has enhanced the detailed analysis of retinal layers. The authors discuss SS-OCTA features of a rare case of retinal arteriovenous malformation. Image analysis revealed the anomalous large-caliber vessels occupying up to the entire retinal thickness with associated echolucent changes in the inner retinal layers surrounding the retinal vessels, along with disruption of the outer retinal layers, including the inner/outer segments of photoreceptors beneath the large tortuous vessels outside the foveola in absence of any capillary nonperfusion areas or lack of significant macular edema. At the fovea, the outer retinal layers were intact due to a smaller caliber and less-deep extension of the anomalous vessels. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:216-219.]. Copyright 2018, SLACK Incorporated.

  11. Recent Advancements in Retinal Vessel Segmentation.

    PubMed

    L Srinidhi, Chetan; Aparna, P; Rajan, Jeny

    2017-04-01

    Retinal vessel segmentation is a key step towards the accurate visualization, diagnosis, early treatment and surgery planning of ocular diseases. For the last two decades, a tremendous amount of research has been dedicated in developing automated methods for segmentation of blood vessels from retinal fundus images. Despite the fact, segmentation of retinal vessels still remains a challenging task due to the presence of abnormalities, varying size and shape of the vessels, non-uniform illumination and anatomical variability between subjects. In this paper, we carry out a systematic review of the most recent advancements in retinal vessel segmentation methods published in last five years. The objectives of this study are as follows: first, we discuss the most crucial preprocessing steps that are involved in accurate segmentation of vessels. Second, we review most recent state-of-the-art retinal vessel segmentation techniques which are classified into different categories based on their main principle. Third, we quantitatively analyse these methods in terms of its sensitivity, specificity, accuracy, area under the curve and discuss newly introduced performance metrics in current literature. Fourth, we discuss the advantages and limitations of the existing segmentation techniques. Finally, we provide an insight into active problems and possible future directions towards building successful computer-aided diagnostic system.

  12. Retinal remodeling in inherited photoreceptor degenerations.

    PubMed

    Marc, Robert E; Jones, Bryan W

    2003-10-01

    Photoreceptor degenerations initiated in rods or the retinal pigmented epithelium usually evoke secondary cone death and sensory deafferentation of the surviving neural retina. In the mature central nervous system, deafferentation evokes atrophy and connective re-patterning. It has been assumed that the neural retina does not remodel, and that it is a passive survivor. Screening of advanced stages of human and rodent retinal degenerations with computational molecular phenotyping has exposed a prolonged period of aggressive negative remodeling in which neurons migrate along aberrant glial columns and seals, restructuring the adult neural retina (1). Many neurons die, but survivors rewire the remnant inner plexiform layer (IPL), forming thousands of novel ectopic microneuromas in the remnant inner nuclear layer (INL). Bipolar and amacrine cells engage in new circuits that are most likely corruptive. Remodeling in human and rodent retinas emerges regardless of the molecular defects that initially trigger retinal degenerations. Although remodeling may constrain therapeutic intervals for molecular, cellular, or bionic rescue, the exposure of intrinsic retinal remodeling by the removal of sensory control in retinal degenerations suggests that neuronal organization in the normal retina may be more plastic than previously believed.

  13. Nanomaterials and Retinal Toxicity | Science Inventory | US ...

    EPA Pesticide Factsheets

    The neuroretina should be considered as a potential site of nanomaterial toxicity. Engineered nanomaterials may reach the retina through three potential routes of exposure including; intra­ vitreal injection of therapeutics; blood-borne delivery in the retinal vasculature and then crossing the blood-retinal barrier; and through the choroidal blood supply, crossing the Bruch's membrane and the retinal pigment epithelium (RPE). The blood-retinal barrier is functionally similar to the blood-brain barrier, normally restricting transport of larger sized materials, but particles in the lower nanomaterial size range can be expected to transit. The blood flow to the retinal choroid is, on a tissue mass basis, one of the highest in the body raising the potential for rapid delivery of nanomaterials to the RPE. In vitro, RPE cells rapidly uptake nano particles, transport and agglomerate them in the perinuclear cytoplasm. In vivo studies have shown that the eye can uptake nanomaterials and retain them longer than many other tissues after cessation of exposure. Toxicity from nanomaterials to the neural retina or the RPE would be expected to follow common mechanisms identified for other tissues including generation of reactive oxygen species, alteration of cellular redox status, altered intracellular signaling, and release of toxic metal ions from soluble metallic particles. The retina and other ocular tissues, however, have potential for additional phototoxic mechanism

  14. Reprogramming the metabolome rescues retinal degeneration.

    PubMed

    Park, Karen Sophia; Xu, Christine L; Cui, Xuan; Tsang, Stephen H

    2018-05-01

    Metabolomics studies in the context of ophthalmology have largely focused on identifying metabolite concentrations that characterize specific retinal diseases. Studies involving mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy have shown that individuals suffering from retinal diseases exhibit metabolic profiles that markedly differ from those of control individuals, supporting the notion that metabolites may serve as easily identifiable biomarkers for specific conditions. An emerging branch of metabolomics resulting from biomarker studies, however, involves the study of retinal metabolic dysfunction as causes of degeneration. Recent publications have identified a number of metabolic processes-including but not limited to glucose and oxygen metabolism-that, when perturbed, play a role in the degeneration of photoreceptor cells. As a result, such studies have led to further research elucidating methods for prolonging photoreceptor survival in an effort to halt degeneration in its early stages. This review will explore the ways in which metabolomics has deepened our understanding of the causes of retinal degeneration and discuss how metabolomics can be used to prevent retinal degeneration from progressing to its later disease stages.

  15. Clinical applications of retinal gene therapy.

    PubMed

    Lipinski, Daniel M; Thake, Miriam; MacLaren, Robert E

    2013-01-01

    Many currently incurable forms of blindness affecting the retina have a genetic etiology and several others, such as those resulting from retinal vascular disturbances, respond to repeated, potentially indefinite administration of molecular based treatments. The recent clinical advances in retinal gene therapy have shown that viral vectors can deliver genes safely to the retina and the promising initial results from a number of clinical trials suggest that certain diseases may potentially be treatable. Gene therapy provides a means of expressing proteins within directly transduced cells with far greater efficacy than might be achieved by traditional systemic pharmacological approaches. Recent developments have demonstrated how vector gene expression may be regulated and further improvements to vector design have limited side effects and improved safety profiles. These recent steps have been most significant in bringing gene therapy into the mainstream of ophthalmology. Nevertheless translating retinal gene therapy from animal research into clinical trials is still a lengthy process, including complexities in human retinal diseases that have been difficult to model in the laboratory. The focus of this review is to summarize the genetic background of the most common retinal diseases, highlight current concepts of gene delivery technology, and relate those technologies to pre-clinical and clinical gene therapy studies. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Functional and Behavioral Metrics for Evaluating Laser Retinal Damage

    DTIC Science & Technology

    2006-01-01

    pigmentosa , and retinal detachment10. mfERG response characteristics have been shown to vary depending on the part of the retina that is affected by a...DoD Controlling Office is (insert controlling DoD office). 20100715258 Functional and behavioral metrics for evaluating laser retinal damage Cheryl...potential for and severity of laser eye injury and retinal damage is increasing . Sensitive and accurate methods to evaluate and follow laser retinal

  17. Towards a Completely Implantable, Light-Sensitive Intraocular Retinal Prosthesis

    DTIC Science & Technology

    2001-10-25

    electronic retinal prosthesis is under development to treat retinitis pigmentosa and age-related macular degeneration, two presently incurable...34Preservation of the inner retina in retinitis pigmentosa . A morphometric analysis," Arch Ophthalmol, vol. 115, no. 4, pp. 511-515, Apr.1997...Towards a completely implantable, light-sensitive intraocular retinal prosthesis. M.S. Humayun, J.D. Weiland, B. Justus1, C. Merrit1, J. Whalen, D

  18. Inherited Retinal Degenerative Disease Clinical Trial Network. Addendum

    DTIC Science & Technology

    2010-10-01

    by retinitis pigmentosa (RP) and other forms of rare inherited retinal degenerative diseases is estimated at approximately 200,000 individuals. RP... Retinitis Pigmentosa ). NNRI is awaiting final protocol review and HRPO approval for NNRI and the three enrolling clinical sites- the CTEC site at...acid) in individuals with autosomal dominant retinitis pigmentosa , with the ability to expand the enrollment to individuals with autosomal recessive

  19. Stimulation of a Suprachoroidal Retinal Prosthesis Drives Cortical Responses in a Feline Model of Retinal Degeneration.

    PubMed

    Aplin, Felix P; Fletcher, Erica L; Luu, Chi D; Vessey, Kirstan A; Allen, Penelope J; Guymer, Robyn H; Shepherd, Robert K; Shivdasani, Mohit N

    2016-10-01

    Retinal prostheses have emerged as a promising technology to restore vision in patients with severe photoreceptor degeneration. To better understand how neural degeneration affects the efficacy of electronic implants, we investigated the function of a suprachoroidal retinal implant in a feline model. Unilateral retinal degeneration was induced in four adult felines by intravitreal injection of adenosine triphosphate (ATP). Twelve weeks post injection, animals received suprachoroidal electrode array implants in each eye, and responses to electrical stimulation were obtained using multiunit recordings from the visual cortex. Histologic measurements of neural and glial changes in the retina at the implant site were correlated with cortical thresholds from individual stimulating electrodes. Adenosine triphosphate-injected eyes displayed changes consistent with mid-to-late stage retinal degeneration and remodeling. A significant increase in electrical charge was required to induce a cortical response from stimulation of the degenerated retina compared to that in the fellow control eye. Spatial and temporal characteristics of the electrically evoked cortical responses were no different between eyes. Individual electrode thresholds varied in both the control and the ATP-injected eyes and were correlated with ganglion cell density. In ATP-injected eyes, cortical threshold was also independently correlated with an increase in the extent of retinal gliosis. These data suggest that even when ganglion cell density remains unaffected, glial changes in the retina following degeneration can influence the efficacy of suprachoroidal electrical stimulation. A better understanding of how glial change impacts retinal prosthesis function may help to further the optimization of retinal implants.

  20. Novel method for edge detection of retinal vessels based on the model of the retinal vascular network and mathematical morphology

    NASA Astrophysics Data System (ADS)

    Xu, Lei; Zheng, Xiaoxiang; Zhang, Hengyi; Yu, Yajun

    1998-09-01

    Accurate edge detection of retinal vessels is a prerequisite for quantitative analysis of subtle morphological changes of retinal vessels under different pathological conditions. A novel method for edge detection of retinal vessels is presented in this paper. Methods: (1) Wavelet-based image preprocessing. (2) The signed edge detection algorithm and mathematical morphological operation are applied to get the approximate regions that contain retinal vessels. (3) By convolving the preprocessed image with a LoG operator only on the detected approximate regions of retinal vessels, followed by edges refining, clear edge maps of the retinal vessels are fast obtained. Results: A detailed performance evaluation together with the existing techniques is given to demonstrate the strong features of our method. Conclusions: True edge locations of retinal vessels can be fast detected with continuous structures of retinal vessels, less non- vessel segments left and insensitivity to noise. The method is also suitable for other application fields such as road edge detection.

  1. Progress toward the maintenance and repair of degenerating retinal circuitry.

    PubMed

    Vugler, Anthony A

    2010-01-01

    Retinal diseases such as age-related macular degeneration and retinitis pigmentosa remain major causes of severe vision loss in humans. Clinical trials for treatment of retinal degenerations are underway and advancements in our understanding of retinal biology in health/disease have implications for novel therapies. A review of retinal biology is used to inform a discussion of current strategies to maintain/repair neural circuitry in age-related macular degeneration, retinitis pigmentosa, and Type 2 Leber congenital amaurosis. In age-related macular degeneration/retinitis pigmentosa, a progressive loss of rods/cones results in corruption of bipolar cell circuitry, although retinal output neurons/photoreceptive melanopsin cells survive. Visual function can be stabilized/enhanced after treatment in age-related macular degeneration, but in advanced degenerations, reorganization of retinal circuitry may preclude attempts to restore cone function. In Type 2 Leber congenital amaurosis, useful vision can be restored by gene therapy where central cones survive. Remarkable progress has been made in restoring vision to rodents using light-responsive ion channels inserted into bipolar cells/retinal ganglion cells. Advances in genetic, cellular, and prosthetic therapies show varying degrees of promise for treating retinal degenerations. While functional benefits can be obtained after early therapeutic interventions, efforts should be made to minimize circuitry changes as soon as possible after rod/cone loss. Advances in retinal anatomy/physiology and genetic technologies should allow refinement of future reparative strategies.

  2. Low Vision Rehabilitation of Retinitis Pigmentosa. Practice Report

    ERIC Educational Resources Information Center

    Rundquist, John

    2004-01-01

    Retinitis pigmentosa is a rod-cone dystrophy, commonly genetic in nature. Approximately 60-80% of those with retinitis pigmentosa inherit it by an autosomal recessive transmission (Brilliant, 1999). There have been some reported cases with no known family history. The symptoms of retinitis pigmentosa are decreased acuity, photophobia, night…

  3. Posterior Retinal Hemorrhages during Retcam Examination for Retinopathy of Prematurity.

    PubMed

    Chandra, Parijat; Azad, Rajvardhan

    2016-11-07

    Retcam-assisted retinopathy of prematurity (ROP) screening is a commonly used safe examination procedure. A preterm baby born at 32 weeks gestation age developed extensive posterior retinal hemorrhages during retinal imaging using the RetCam. Retinal hemorrhages spontaneously resolved. As tele screening is becomes more popular, proper training for Retcam usage is essential.

  4. Repetitive magnetic stimulation improves retinal function in a rat model of retinal dystrophy

    NASA Astrophysics Data System (ADS)

    Rotenstreich, Ygal; Tzameret, Adi; Levi, Nir; Kalish, Sapir; Sher, Ifat; Zangen, Avraham; Belkin, Michael

    2014-02-01

    Vision incapacitation and blindness associated with retinal dystrophies affect millions of people worldwide. Retinal degeneration is characterized by photoreceptor cell death and concomitant remodeling of remaining retinal cells. Repetitive Magnetic Stimulation (RMS) is a non-invasive technique that creates alternating magnetic fields by brief electric currents transmitted through an insulated coil. These magnetic field generate action potentials in neurons, and modulate the expression of neurotransmitter receptors, growth factors and transcription factors which mediate plasticity. This technology has been proven effective and safe in various psychiatric disorders. Here we determined the effect of RMS on retinal function in Royal College of Surgeons (RCS) rats, a model for retinal dystrophy. Four week-old RCS and control Spargue Dawley (SD) rats received sham or RMS treatment over the right eye (12 sessions on 4 weeks). RMS treatment at intensity of at 40% of the maximal output of a Rapid2 stimulator significantly increased the electroretinogram (ERG) b-wave responses by up to 6- or 10-fold in the left and right eye respectively, 3-5 weeks following end of treatment. RMS treatment at intensity of 25% of the maximal output did not significant effect b-wave responses following end of treatment with no adverse effect on ERG response or retinal structure of SD rats. Our findings suggest that RMS treatment induces delayed improvement of retinal functions and may induce plasticity in the retinal tissue. Furthermore, this non-invasive treatment may possibly be used in the future as a primary or adjuvant treatment for retinal dystrophy.

  5. Retrospective study of rhegmatogenous retinal detachments secondary to round retinal holes.

    PubMed

    Williams, Katie M; Dogramaci, Mahmut; Williamson, Tom H

    2012-01-01

    The authors aim to analyze the incidence, characteristics, surgical management, and outcome of patients presenting to St Thomas' Hospital with a rhegmatogenous retinal detachment secondary to atrophic round retinal holes. This is a retrospective collation of patients presenting to a single surgeon with a round hole-associated retinal detachment between 2001 and 2009. Specific collation of demographics, retinal detachment features, choice of management, complications, requirement for further surgery, and ultimate surgical success with final visual acuity is reported. Fifty-six patients with a retinal detachment secondary to a round hole were identified (4.49% incidence). The cohort had a median age of 28.9 years (range 14 to 39) and a female predominance (64%). The median spherical equivalent refractive error was -5.5 diopters (range -1 to -18). The commonest quadrant with retinal holes was the inferotemporal quadrant (40% of patients). Approximately half of our cohort were identified to have lattice degeneration at any site and in either eye. The majority of patients received an external nondrainage procedure (92%) with cryotherapy (88%) and an explant (94%). Three patients required further surgery to achieve retinal reattachment and 12% required surgery for a retinal detachment in the fellow eye. At final follow-up, 78% achieved a visual acuity of 0.18 logMAR (6/12 Snellen) or better and the median final visual acuity was 0.00 logMAR (6/6 Snellen). Retinal detachments secondary to round holes have consistent characteristic features (young, myopic, female, inferior detachment). Surgical management is increasingly advocated and most achieve primary surgical success with a good final visual acuity.

  6. Inferior retinal light exposure is more effective than superior retinal exposure in suppressing melatonin in humans

    NASA Technical Reports Server (NTRS)

    Glickman, Gena; Hanifin, John P.; Rollag, Mark D.; Wang, Jenny; Cooper, Howard; Brainard, George C.

    2003-01-01

    Illumination of different areas of the human retina elicits differences in acute light-induced suppression of melatonin. The aim of this study was to compare changes in plasma melatonin levels when light exposures of equal illuminance and equal photon dose were administered to superior, inferior, and full retinal fields. Nine healthy subjects participated in the study. Plexiglass eye shields were modified to permit selective exposure of the superior and inferior halves of the retinas of each subject. The Humphrey Visual Field Analyzer was used both to confirm intact full visual fields and to quantify exposure of upper and lower visual fields. On study nights, eyes were dilated, and subjects were exposed to patternless white light for 90 min between 0200 and 0330 under five conditions: (1) full retinal exposure at 200 lux, (2) full retinal exposure at 100 lux, (3) inferior retinal exposure at 200 lux, (4) superior retinal exposure at 200 lux, and (5) a dark-exposed control. Plasma melatonin levels were determined by radioimmunoassay. ANOVA demonstrated a significant effect of exposure condition (F = 5.91, p < 0.005). Post hoc Fisher PLSD tests showed significant (p < 0.05) melatonin suppression of both full retinal exposures as well as the inferior retinal exposure; however, superior retinal exposure was significantly less effective in suppressing melatonin. Furthermore, suppression with superior retinal exposure was not significantly different from that of the dark control condition. The results indicate that the inferior retina contributes more to the light-induced suppression of melatonin than the superior retina at the photon dosages tested in this study. Findings suggest a greater sensitivity or denser distribution of photoreceptors in the inferior retina are involved in light detection for the retinohypothalamic tract of humans.

  7. [Stickler syndrome with rhegmatogenous retinal detachment].

    PubMed

    Watanabe, Hiroka; Kohzaki, Kenichi; Kubo, Hiroyuki; Okano, Kiichiro; Watanabe, Akira; Tsuneoka, Hiroshi

    2010-05-01

    Stickler syndrome is an autosomal dominant disease characterized by various disorders of the eyes and the connective tissues throughout the body. It can arise from a mutation in the collagen associated gene. We present a case of Stickler syndrome with rhegmatogenous retinal detachment. A 10-years-old boy was referred to us with rhegmatogenous retinal detachment of the right eye. His family history included eye disease and a cleft palate. He had high myopia, vitreous liquefaction and lattice degeneration in the both eye. He also had a cleft palate and a broad nasal bridge. His condition was diagnosed as Stickler syndrome. We performed vitrectomy, scleral buckling and encircling, and silicone oil injection in the right eye. We also did a reattachment of the retina in the right eye. Pediatric retinal detachment may indicate the presence of Stickler syndrome and a complete examination of the eye as well as a full family history must be obtained in such cases.

  8. Computer-aided retinal photocoagulation system

    NASA Astrophysics Data System (ADS)

    Barrett, Steven F.; Wright, Cameron H.; Jerath, Maya R.; Lewis, R. Stephen; Dillard, Bryan C.; Rylander, Henry G.; Welch, Ashley J.

    1996-01-01

    Researchers at the University of Texas at Austin's Biomedical Engineering Laser Laboratory and the U.S. Air Force Academy's Department of Electrical Engineering are developing a computer-assisted prototype retinal photocoagulation system. The project goal is to rapidly and precisely automatically place laser lesions in the retina for the treatment of disorders such as diabetic retinopathy and retinal tears while dynamically controlling the extent of the lesion. Separate prototype subsystems have been developed to control lesion parameters (diameter or depth) using lesion reflectance feedback and lesion placement using retinal vessels as tracking landmarks. Successful subsystem testing results in vivo on pigmented rabbits using an argon continuous wave laser are presented. A prototype integrated system design to simultaneously control lesion parameters and placement at clinically significant speeds is provided.

  9. Automated retinal layer segmentation and characterization

    NASA Astrophysics Data System (ADS)

    Luisi, Jonathan; Briley, David; Boretsky, Adam; Motamedi, Massoud

    2014-05-01

    Spectral Domain Optical Coherence Tomography (SD-OCT) is a valuable diagnostic tool in both clinical and research settings. The depth-resolved intensity profiles generated by light backscattered from discrete layers of the retina provide a non-invasive method of investigating progressive diseases and injury within the eye. This study demonstrates the application of steerable convolution filters capable of automatically separating gradient orientations to identify edges and delineate tissue boundaries. The edge maps were recombined to measure thickness of individual retinal layers. This technique was successfully applied to longitudinally monitor changes in retinal morphology in a mouse model of laser-induced choroidal neovascularization (CNV) and human data from age-related macular degeneration patients. The steerable filters allow for direct segmentation of noisy images, while novel recombination of weaker segmentations allow for denoising post-segmentation. The segmentation before denoising strategy allows the rapid detection of thin retinal layers even under suboptimal imaging conditions.

  10. Retinal thickness measurement after phacoemulsification.

    PubMed

    Cohen, Kenneth L; Patel, Sheel B; Ray, Neepa

    2004-07-01

    To measure macular thickness using the Retinal Thickness Analyzer (RTA) (Talia Technologies, Ltd.) before and after routine phacoemulsification. Ophthalmology Clinic, Ambulatory Care Center, University of North Carolina at Chapel Hill, School of Medicine, and the University of North Carolina Hospitals, Chapel Hill, North Carolina, USA. Thirty-five nonconsecutive patients scheduled for phacoemulsification and posterior chamber intraocular lens implantation were recruited. The best corrected visual acuity (BCVA) and macular thickness in the surgical and nonsurgical eyes were measured with the RTA prior to surgery and 1 and 6 weeks after surgery. Wilcoxon signed rank tests were used to evaluate each index of macular thickness--the mean posterior pole, perifoveal, and foveal thicknesses--over the 3 time periods and to compare the indices before surgery in surgical and nonsurgical eyes. Spearman correlations were computed for each index and the BCVA. Significance was assessed at the 5% level. Preoperatively, all indices were higher in surgical [corrected] eyes than in nonsurgical [corrected] eyes. In surgical eyes, all indices decreased from preoperatively to 6 weeks after surgery. In nonsurgical eyes, there was no change. The BCVA in surgical eyes improved from before surgery to 1 week and 6 weeks after surgery. In surgical eyes, there were nonsignificant negative correlations between each index and the BCVA before surgery and 1 and 6 weeks after surgery. In nonsurgical eyes, there were nonsignificant negative correlations between each index and the BCVA preoperatively and 6 weeks after surgery, except for a significant negative correlation for the foveal index at 6 weeks. Measurements by the RTA indicate that the decrease in macular thickness indices in surgical eyes from before surgery to 6 weeks after routine phacoemulsification is an artifact of imaging the retina through hazy media. Therefore, the results must be interpreted in the context of the clinical

  11. Preservation of retinotopic map in retinal degeneration

    PubMed Central

    Xie, John; Wang, Gene-Jack; Yow, Lindy; Humayun, Mark S.; Weiland, James D.; Cela, Carlos J.; Jadvar, Hossein; Lazzi, Gianluca; Dhrami-Gavazi, Elona; Tsang, Stephen H.

    2015-01-01

    Retinal degenerations trigger the loss of photoreceptors and cause the remaining de-afferented neural retina to undergo remodeling. Concerns over this potential retinal synaptic reorganization following visual loss have raised questions regarding the usefulness of visual restoration via retinal electrical stimulation. We have used quantitative positron emission tomography (PET) and 2-deoxy-2-[18F]fluoro-d-glucose (FDG) to objectively evaluate the connection between the retina and the primary visual cortex under both light and transcorneal electrical stimulation (TcES) in five subjects with retinal degeneration (RD) who have had more than ten years of light-perception-only best visual acuity and five age-matched normal-sighted controls. All subjects underwent quantitative PET with FDG as the metabolic tracer during stimulation of the right eye under both light stimulation condition and transcorneal electrical stimulation (TcES) using ERG-Jet contact lens electrode. Cortical activation maps from each stimulation condition were obtained using statistical parametric mapping. TcES phosphene threshold current and qualitative visual cortex activation from both stimulation conditions were compared between the two subject groups. Average phosphene threshold current was 0.72 ± 0.18 mA for the five normal-sighted controls and 3.08 ± 2.01 mA for the retinal degenerative subjects. Phosphene threshold current was significantly higher in retinal degenerative subjects compared to normal-sighted controls (p < 0.05). We found both light stimulation and TcES resulted in retinotopically mapped primary visual cortex activation in both groups. In addition, the patterns of early visual area activation between the two subject groups are more similar during TcES than light stimulation. Our findings suggest primary visual cortex continues to maintain its retinotopy in RD subjects despite prolonged visual loss. PMID:22685713

  12. 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

  13. Reading Visual Braille with a Retinal Prosthesis

    PubMed Central

    Lauritzen, Thomas Z.; Harris, Jordan; Mohand-Said, Saddek; Sahel, Jose A.; Dorn, Jessy D.; McClure, Kelly; Greenberg, Robert J.

    2012-01-01

    Retinal prostheses, which restore partial vision to patients blinded by outer retinal degeneration, are currently in clinical trial. The Argus II retinal prosthesis system was recently awarded CE approval for commercial use in Europe. While retinal prosthesis users have achieved remarkable visual improvement to the point of reading letters and short sentences, the reading process is still fairly cumbersome. This study investigates the possibility of using an epiretinal prosthesis to stimulate visual braille as a sensory substitution for reading written letters and words. The Argus II retinal prosthesis system, used in this study, includes a 10 × 6 electrode array implanted epiretinally, a tiny video camera mounted on a pair of glasses, and a wearable computer that processes the video and determines the stimulation current of each electrode in real time. In the braille reading system, individual letters are created by a subset of dots from a 3 by 2 array of six dots. For the visual braille experiment, a grid of six electrodes was chosen out of the 10 × 6 Argus II array. Groups of these electrodes were then directly stimulated (bypassing the camera) to create visual percepts of individual braille letters. Experiments were performed in a single subject. Single letters were stimulated in an alternative forced choice (AFC) paradigm, and short 2–4-letter words were stimulated (one letter at a time) in an open-choice reading paradigm. The subject correctly identified 89% of single letters, 80% of 2-letter, 60% of 3-letter, and 70% of 4-letter words. This work suggests that text can successfully be stimulated and read as visual braille in retinal prosthesis patients. PMID:23189036

  14. Reading visual braille with a retinal prosthesis.

    PubMed

    Lauritzen, Thomas Z; Harris, Jordan; Mohand-Said, Saddek; Sahel, Jose A; Dorn, Jessy D; McClure, Kelly; Greenberg, Robert J

    2012-01-01

    Retinal prostheses, which restore partial vision to patients blinded by outer retinal degeneration, are currently in clinical trial. The Argus II retinal prosthesis system was recently awarded CE approval for commercial use in Europe. While retinal prosthesis users have achieved remarkable visual improvement to the point of reading letters and short sentences, the reading process is still fairly cumbersome. This study investigates the possibility of using an epiretinal prosthesis to stimulate visual braille as a sensory substitution for reading written letters and words. The Argus II retinal prosthesis system, used in this study, includes a 10 × 6 electrode array implanted epiretinally, a tiny video camera mounted on a pair of glasses, and a wearable computer that processes the video and determines the stimulation current of each electrode in real time. In the braille reading system, individual letters are created by a subset of dots from a 3 by 2 array of six dots. For the visual braille experiment, a grid of six electrodes was chosen out of the 10 × 6 Argus II array. Groups of these electrodes were then directly stimulated (bypassing the camera) to create visual percepts of individual braille letters. Experiments were performed in a single subject. Single letters were stimulated in an alternative forced choice (AFC) paradigm, and short 2-4-letter words were stimulated (one letter at a time) in an open-choice reading paradigm. The subject correctly identified 89% of single letters, 80% of 2-letter, 60% of 3-letter, and 70% of 4-letter words. This work suggests that text can successfully be stimulated and read as visual braille in retinal prosthesis patients.

  15. Fundus Autofluorescence Lifetime Patterns in Retinitis Pigmentosa.

    PubMed

    Dysli, Chantal; Schürch, Kaspar; Pascal, Escher; Wolf, Sebastian; Zinkernagel, Martin S

    2018-04-01

    We investigated whether fundus autofluorescence (FAF) lifetimes in patients with retinitis pigmentosa display a disease-specific lifetime pattern. Fundus autofluorescence lifetime imaging ophthalmoscopy (FLIO) was performed in two spectral channels (498-560 and 560-720 nm) after excitation with a 473 nm pulsed laser in patients with retinitis pigmentosa and compared to healthy controls of a similar age range. Corresponding FAF intensity and spectral domain optical coherence tomography (OCT) data, as well as best corrected visual acuity (BCVA) were acquired and compared to fluorescence lifetime data. We investigated 43 eyes from 43 patients with retinitis pigmentosa (mean age 45 ± 15 years) and compared them to eyes of 13 age-matched healthy participants. Mean FAF lifetimes were prolonged in areas of photoreceptor atrophy with preserved retinal pigment epithelium (RPE) (P = 0.0036) and even longer in areas with total atrophy of photoreceptors and RPE (P = 0.0002). The prevalence of perifoveal ring structures characterized by prolonged fluorescence lifetimes in FLIO was higher (63% vs. 49%) and the rings were wider compared to the hyperautofluorescent rings in qualitative fundus autofluorescence intensity images. In the central fovea with intact retinal layer structure identified by OCT, fluorescence lifetimes were slightly prolonged compared to those of age-matched healthy controls (short spectral channel [SSC], P = 0.0044; long spectral channel [LSC], P = 0.0128). Short lifetimes within the macular center were negatively correlated with BCVA (R2 = 0.33, P < 0.0001) as well as the greatest diameter of the ellipsoid band in OCT. FLIO in retinitis pigmentosa reveals characteristic patterns that allow identification of areas of photoreceptor atrophy, RPE atrophy, and remaining photoreceptor segments in areas of RPE atrophy. Fluorescence lifetimes can be used to identify ellipsoid zone loss that correlates with functional parameters.

  16. Two actinide-organic frameworks constructed by a tripodal flexible ligand: Occurrence of infinite ((UO{sub 2})O{sub 2}(OH){sub 3}){sub 4n} and hexanuclear (Th{sub 6}O{sub 4}(OH){sub 4}) motifs

    SciTech Connect

    Liang, Lingling; Zhang, Ronglan; Zhao, Jianshe, E-mail: jszhao@nwu.edu.cn

    2016-11-15

    Two new actinide metal-organic frameworks were constructed by using a tripodal flexible ligand tris (2-carboxyethyl) isocyanurate (H{sub 3}tci) under hydrothermal condition. The combination of H{sub 3}tci and uranyl nitrate hexahydrate in aqueous solution leads to the isolation of [(UO{sub 2}){sub 2}(H{sub 2}O){sub 4}]{sub 0.5}(tci){sub 2}(UO{sub 2}){sub 4}(OH){sub 4}·18H{sub 2}O (1), which contains two distinct UO{sub 2}{sup 2+} coordination environments. Four uranyl cations, linked through μ{sub 3}-OH respectively, result in the edge-sharing ribbons. Then, the layer structure is constructed by U-O clusters linked through other eight-coordinated uranyl unions, giving rise to a porous structure in the space. Topological analysis reveals thatmore » complex 1 belongs to a (4, 8)-connected net with a schläfli symbol of (3{sup 4.}2{sup 6.}3){sub 2}(3{sup 4.}4{sup 6.}5{sup 6.}6{sup 8.}7{sup 3.}8). Th{sub 3}(tci){sub 2}O{sub 2}(OH){sub 2}(H{sub 2}O){sub 3}·12H{sub 2}O (2) generated by the reaction of H{sub 3}tci and thorium nitrate tetrahydrate, possesses nine-fold coodinated Th(IV) centers with a monocapped square antiprismatic geometry. The hexamers “Th{sub 6}O{sub 4}(OH){sub 4}” motifs are connected together by the carboxylate groups, showing a three-dimensional structures. Complex 2 takes on an 8-connected architecture and the point symbol is (4{sup 24.}6{sup 4}). - Graphical abstract: Two new 3D actinide metal-organic frameworks were constructed by using a tripodal flexible ligand tris (2-carboxyethyl) isocyanurate (H3tci) and their topological structures were displayed. The infinite ((UO{sub 2})O{sub 2}(OH){sub 3}){sub 4n} and hexanuclear (Th{sub 6}O{sub 4}(OH){sub 4}) motifs were found in the title actinides networks.« less

  17. New nonlinear optical potassium iodate K[IO{sub 3}] and borates K{sub 3}[B{sub 6}O{sub 10}]Br, KTa[B{sub 4}O{sub 6}(OH){sub 4}](OH){sub 2}{center_dot}1.33H{sub 2}O-Synthesis, structures and relation to the properties

    SciTech Connect

    Belokoneva, Elena L., E-mail: elbel@geol.msu.ru; Stefanovich, Sergej Yu; Dimitrova, Olga V.

    2012-11-15

    Three optically uniaxial non-centrosymmetric potassium compounds, iodate K[IO{sub 3}] and two borates K{sub 3}[B{sub 6}O{sub 10}]Br, KTa[B{sub 4}O{sub 6}(OH){sub 4}](OH){sub 2}{center_dot}1.33H{sub 2}O have been synthesized and characterized by single-crystal X-ray diffraction. The materials were synthesized through hydrothermal techniques using initial reagents and mineralizers. All the compounds are trigonal-hexagonal: the space groups are R3 (K[IO{sub 3}]), R3m (K[B{sub 6}O{sub 10}]Br) and P-62m (KTa[B{sub 4}O{sub 6}(OH){sub 4}](OH){sub 2}{center_dot}1.33H{sub 2}O). Powder second-harmonic generation (SHG) measurements on crystals, using 1064 nm Nd:YAG laser radiation, indicate the materials are all phase-matchable and have strong second-order nonlinearities. The correlation with the perovskite structure has been foundmore » and described for K,Br-borate and K-iodate. Structure-properties relation is discussed and attributed to stereo-active lone-pair on I{sup 5+} and asymmetrical bonds in the compounds. The role of K atoms is pronounced from crystal chemistry point of view, contributing optical nonlinearities. - Graphical abstract: Structure-properties relation is attributed to stereo-active lone-pair on I{sup 5+} and asymmetrical bonds in the compounds with the crucial role of K atoms, K[IO{sub 3}] structure along 3-fold axis with umbrella-like IO{sub 3}-group and with octahedral coordination-analog with perovskite. Highlights: Black-Right-Pointing-Pointer Syntheses in hydrothermal conditions trigonal KIO{sub 3}, K{sub 3}[B{sub 6}O{sub 10}]Br and KTa[B{sub 4}O{sub 6}(OH){sub 4}](OH){sub 2}. Black-Right-Pointing-Pointer Correlation with the perovskite, found for K-iodate and K,Br-borate. Black-Right-Pointing-Pointer Structure-properties relation, attributed to I{sup 5+} lone-pair and asymmetric bonds including K-atoms. Black-Right-Pointing-Pointer The compounds are phase matchable and strongly nonlinear from powder SHG measurements. Black

  18. The surface morphology of retinal breaks and lattice retinal degeneration. A scanning electron microscopic study.

    PubMed

    Robinson, M R; Streeten, B W

    1986-02-01

    In 14 of 110 eye bank eyes, lesions characteristic of peripheral retinal surface pathology were examined by scanning electron microscopy (SEM). These included operculated and flap tears, trophic round holes, lattice degeneration with holes, and paravascular retinal "pitting" degeneration. By SEM, the edges of the retinal breaks were covered by smooth cellular membranes, merging peripherally with a meshwork of vitreous fibrils. The membrane cells had poorly defined borders, a pitted surface, and variable numbers of microvilli consistent with glia. Lattice surfaces and foci of paravascular retinal degeneration were covered by similar membrane, but showed characteristic differences. It appears that breaks in the internal limiting membrane always stimulate proliferation of preretinal glial membranes. Similar cellular morphology of the membranes associated with breaks is consistent with a common cell of origin. Limited proliferation of these membranes suggests that surface gliosis is normally inhibited when the cells contact either intact basement membrane or vitreous.

  19. CLINICAL PRESENTATIONS AND OUTCOMES OF RHEGMATOGENOUS RETINAL DETACHMENT IN RETINITIS PIGMENTOSA.

    PubMed

    Dave, Vivek P; Jalali, Subhadra; Nayaka, Ashraya; Pappuru, Rajeev R; Pathengay, Avinash; Das, Taraprasad

    2016-07-01

    To describe the clinical presentations and outcomes of rhegmatogenous retinal detachments (RRD) in eyes with retinitis pigmentosa. A retrospective review of all patients of retinitis pigmentosa with RRD from January 1990 to December 2013 at a tertiary eye care institute. Of total 28,622 patients of retinitis pigmentosa over a 23-year period, 17 eyes of 17 patients had RRD. Mean age at presentation was 34.53 ± 16.42 years (median 32 years). Median duration of decreased vision attributed to RRD was 6 months. Ten eyes (59%) had cataract and 3 eyes (18%) had history of cataract surgery. Thirteen eyes (76%) had inferior retinal detachment; 9 eyes (53%) had lattice with retinal holes; and 8 eyes (47%) had atrophic retinal holes. There were no horse-shoe tears, giant retinal tears, dialysis, and macular holes related RRD. Majority (82%) of retinal breaks were in the inferotemporal quadrant. Only 3 eyes (18%) had proliferative vitreoretinopathy at presentation. Twelve eyes at presentation had best-corrected visual acuity <20/200 and 6 eyes had only light perception. The macula was involved by the detachment in all cases. Mean preoperative visual acuity was 1.4 ± 0.88 logarithm of the minimum angle of resolution (median 1.3, range 3-0.1; 20/502). Surgery was not advised in 6 eyes (35% patients); 5 eyes (30%) underwent scleral buckling and 6 eyes (35%) underwent vitrectomy. Median follow-up was 5 months. Reattachment rate at last follow-up was 91% (15 eyes). Mean postoperative best-corrected visual acuity recorded was 1.06 ± 0.8 (median 1, range 3-0.1; 20/229) (P = 0.15). Eight eyes at last visit had best-corrected visual acuity <20/200. Of the 11 eyes operated, 4 improved in vision and 7 retained the preoperative vision. The incidence of RRD in retinitis pigmentosa is very low. Presentation, although delayed, is at a younger age. Horse-shoe tears and proliferative vitreoretinopathy are uncommon; cataract is a common coexisting pathology. Surgical reattachment rates

  20. The Blood-Retinal Barrier in the Management of Retinal Disease: EURETINA Award Lecture.

    PubMed

    Cunha-Vaz, José

    2017-01-01

    Retinal diseases are the main causes of blindness in the Western world. Diabetic retinopathy and age-related macular degeneration continue to increase in prevalence and as main causes of vision loss. Intravitreal anti-VEGF and steroid injections have raised new expectations for their successful treatment. These agents act by stabilizing the blood-retinal barrier (BRB). Our group defined the BRB by identifying for the first time the tight junctions that unite retinal endothelial cells and are the basis for the inner BRB, an observation later confirmed in retinal pigment epithelial cells and in brain vessels. A major role of active transport processes was also identified. Today, the BRB is understood to play a fundamental role in retinal function in both health and disease. Retinal edema, an ubiquitous manifestation of retinal disease, is directly associated with breakdown of the BRB and with vision loss. In its most common form (i.e., vasogenic edema), due to breakdown of the BRB, Starling's law of capillary filtration may be used to interpret the mechanisms of fluid accumulation in the retina. The main factors involved in the development of retinal edema are BRB permeability, capillary hydrostatic pressure, tissue hydrostatic pressure, tissue osmotic pressure, and plasma osmotic pressure. In the clinical environment, breakdown of the BRB has been identified by fluorescein angiography and vitreous fluorometry, requiring the intravenous administration of fluorescein. An OCT-based method, OCT-Leakage, recently introduced by our group is capable of noninvasively identifying and quantifying sites of alteration of the BRB by mapping areas of lower-than-normal optical reflectivity, thus reflecting changes in the retinal extracellular fluid. We found good correspondence between the location of increased areas of low optical reflectivity identified by OCT-Leakage and the main sites of leakage on fluorescein angiography. Furthermore, with OCT-Leakage the areas of abnormal

  1. RETINAL NEOVASCULARIZATION FROM A PATIENT WITH CUTIS MARMORATA TELANGIECTATICA CONGENITA.

    PubMed

    Sassalos, Thérèse M; Fields, Taylor S; Levine, Robert; Gao, Hua

    2018-03-14

    To report a rare case of peripheral retinal neovascularization in a patient diagnosed with cutis marmorata telangiectatica congenita (CMTC). Observational case report. A 16-year-old girl was referred to clinic for retinal evaluation. The patient had a clinical diagnosis of CMTC later confirmed by skin biopsy. Examination revealed temporal peripheral retinal sheathing, as well as lattice degeneration in both eyes. Wide-field fluorescein angiogram showed substantive peripheral retinal nonperfusion with evidence of vascular leakage from areas of presumed retinal neovascularization. The patient subsequently had pan retinal photocoagulation laser treatment to each eye without complication. Cutis marmorata telangiectatica congenita is a rare vascular condition known to affect multiple organ systems including the eyes. Although ocular manifestations of CMTC are rare, instances of congenital glaucoma, suprachoroidal hemorrhage, and bilateral total retinal detachments resulting in secondary neovascular glaucoma have been reported. Our patient demonstrates the first reported findings of peripheral nonperfusion and retinal neovascularization related to CMTC in a 16-year-old girl. We propose early retinal examination, wide-field fluorescein angiogram, and early pan retinal photocoagulation laser treatment in patients with peripheral nonperfusion and retinal neovascularization from CMTC.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.

  2. Reduced light sensitivity due to impaired retinal perfusion in branch retinal vein occlusion.

    PubMed

    Iijima, Hiroyuki

    2018-03-01

    To study the reduction in light sensitivity in areas where impaired retinal perfusion was established by fluorescein angiogram (FA) in eyes with branch retinal vein occlusion (BRVO) that recovered from retinal edema and hemorrhage. Retrospective observational case series. A study of the reduction in light sensitivity demonstrated by total deviation display of the Humphrey perimetry program 30-2 in 43 eyes from 42 patients with BRVO, whose perfusion status was assessed by FA images taken at least 6 months after disease onset. Each of the 15 retinal squares in the FA images, corresponding to the 15 Humphrey test points around the fixation point in the affected vertical hemisphere, was classified as either perfused, partially perfused, or non-perfused. Correlation between light sensitivity and perfusion status was investigated by three evaluators in a total of 645 squares, 15 squares from each of the 43 subject eyes. In 459 retinal squares (71.2%) with complete agreement on the perfusion status among the three evaluators, light sensitivity was significantly different among retinal squares of perfused (median: - 4.0 dB, n = 258), partially perfused (median: - 8.0 dB, n = 41), and non-perfused (median: - 16.0 dB, n = 160) (P < .000001, Kruskal-Wallis test). Light sensitivity is decreased in retinal areas exhibiting impaired perfusion, likely due to neuronal loss in the inner retinal layer in eyes with chronic BRVO.

  3. Peripheral Retinal Vascular Patterns in Patients with Rhegmatogenous Retinal Detachment in Taiwan

    PubMed Central

    Chen, San-Ni; Hwang, Jiunn-Feng; Wu, Wen-Chuan

    2016-01-01

    This is an observational study of fluorescein angiography (FA) in consecutive patients with rhegmatogenous retinal detachment (RRD) in Changhua Christian Hospital to investigate the peripheral retinal vascular patterns in those patients. All patients had their age, sex, axial length (AXL), and refraction status (RF) recorded. According to the findings in FA of the peripheral retina, the eyes were divided into 4 groups: in group 1, there was a ramified pattern of peripheral retinal vasculature with gradual tapering; in group 2, there was an abrupt ending of peripheral vasculature with peripheral non-perfusion; in group 3, there was a curving route of peripheral vasculature forming vascular arcades or anastomosis; and in group 4, the same as in group 3, but with one or more wedge-shaped avascular notches. Comparisons of age, sex, AXL, and RF, association of breaks with lattice degeneration and retinal non-perfusion, surgical procedures utilized, and mean numbers of operations were made among the four groups. Of the 73 eyes studied, there were 13 eyes (17.8%) in group 1, 3 eyes (4.1%) in group 2, 40 eyes (54.8%) in group 3 and 17 eyes (23.3%) in group 4. Significant differences in age, AXL and RF, and association of retinal breaks to non-perfusion were noted among the four groups. Patients in group 1 had older ages, while younger ages were noted in groups 3 and 4. Eyes in group 1 had the shortest average AXL and were least myopic in contrast to the eyes in groups 3 and 4. Association of retinal breaks and retinal non-perfusion was significantly higher in groups 2, 3 and 4 than in group 1. In conclusion, peripheral vascular anomalies are common in cases with RRD. Patients with peripheral non-perfusion tend to be younger, with longer axial length and have the breaks associated with retinal non-perfusion. PMID:26909812

  4. Peripheral Retinal Vascular Patterns in Patients with Rhegmatogenous Retinal Detachment in Taiwan.

    PubMed

    Chen, San-Ni; Hwang, Jiunn-Feng; Wu, Wen-Chuan

    2016-01-01

    This is an observational study of fluorescein angiography (FA) in consecutive patients with rhegmatogenous retinal detachment (RRD) in Changhua Christian Hospital to investigate the peripheral retinal vascular patterns in those patients. All patients had their age, sex, axial length (AXL), and refraction status (RF) recorded. According to the findings in FA of the peripheral retina, the eyes were divided into 4 groups: in group 1, there was a ramified pattern of peripheral retinal vasculature with gradual tapering; in group 2, there was an abrupt ending of peripheral vasculature with peripheral non-perfusion; in group 3, there was a curving route of peripheral vasculature forming vascular arcades or anastomosis; and in group 4, the same as in group 3, but with one or more wedge-shaped avascular notches. Comparisons of age, sex, AXL, and RF, association of breaks with lattice degeneration and retinal non-perfusion, surgical procedures utilized, and mean numbers of operations were made among the four groups. Of the 73 eyes studied, there were 13 eyes (17.8%) in group 1, 3 eyes (4.1%) in group 2, 40 eyes (54.8%) in group 3 and 17 eyes (23.3%) in group 4. Significant differences in age, AXL and RF, and association of retinal breaks to non-perfusion were noted among the four groups. Patients in group 1 had older ages, while younger ages were noted in groups 3 and 4. Eyes in group 1 had the shortest average AXL and were least myopic in contrast to the eyes in groups 3 and 4. Association of retinal breaks and retinal non-perfusion was significantly higher in groups 2, 3 and 4 than in group 1. In conclusion, peripheral vascular anomalies are common in cases with RRD. Patients with peripheral non-perfusion tend to be younger, with longer axial length and have the breaks associated with retinal non-perfusion.

  5. Retinal prosthesis safety: alterations in microglia morphology due to thermal damage and retinal implant contact.

    PubMed

    Opie, Nicholas L; Greferath, Ursula; Vessey, Kirstan A; Burkitt, Anthony N; Meffin, Hamish; Grayden, David B; Fletcher, Erica L

    2012-11-27

    In order to develop retinal implants with a large number of electrodes, it is necessary to ensure that they do not cause damage to the neural tissue by the heat that the electrical circuits generate. Knowledge about the threshold of the amount of power that induces damage will assist in developing power budgets for retinal implants. Heat-induced retinal damage was evaluated by measuring changes in the morphology of the resident immune cells, the microglia, which are the first cells to respond to retinal trauma. Microglial soma and arbor areas were assessed in rat retinal tissues in vitro to determine the effects of increasing temperatures, implant contact, and heating and implant contact combined. In response to increasing incubation temperatures (no implant), microglial somas enlarged and arbor areas retracted, indicative of retinal stress. Thermal damage thresholds, defined as a significant change in microglial morphology from that observed at the upper limit of normal body temperature, occurred at a temperature of 38.7 °C. Implant contact, induced when a passive implant was placed on the retina, also caused similar morphological alterations in microglia, indicating retinal damage. Heated-implant contact exacerbated the effects of temperature alone but still resulted in a thermal damage threshold of 38.7 °C, the same as with heating alone. Our conservative recommendations are that implanted retinal electronics keep power dissipations to less than 19 mW/mm(2) to stay below the microglial thermal damage threshold (2.1 °C) and to comply with international standards for implantable devices (2 °C).

  6. Retinal Changes in an ATP-Induced Model of Retinal Degeneration

    PubMed Central

    Aplin, Felix P.; Vessey, Kirstan A.; Luu, Chi D.; Guymer, Robyn H.; Shepherd, Robert K.; Fletcher, Erica L.

    2016-01-01

    In rodents and felines, intravitreal administration of adenosine triphosphate (ATP) has been shown to induce photoreceptor death providing a tractable model of retinal degeneration in these species. This study investigated the long term effects of photoreceptor loss in an ATP induced feline model of retinal degeneration. Six normal sighted felines were unilaterally blinded using intravitreal ATP injections and assessed using electroretinography (ERG) and optical coherence tomography (OCT). At 30 h (n = 3) or 12 weeks (n = 3) post-injection, the animals were euthanized and the eyes enucleated. Retinae were sectioned and labeled using immunohistochemistry for markers of cell death, neural remodeling and gliosis. Ongoing cell death and retinal degeneration was observed in the outer retina at both 30 h and 12 weeks following unilateral ATP injection. Markers of mid to late-stage retinal remodeling such as cell displacement and aberrant neurite growth were observed in the inner retina at 12 weeks post-injection. Ganglion cells appeared to remain intact in ATP injected eyes. Müller cell gliosis was observed throughout the inner and outer retina, in some parts completely enveloping and/or displacing the surviving neural tissue. Our data suggests that the ATP injected feline retina continues to undergo progressive retinal degeneration and exhibits abnormalities consistent with a description of retinal remodeling commonly seen in other models of retinal degeneration. These findings validate the use of intravitreal ATP injection in feline as a large animal model of retinal degeneration which may aid in development of therapies aiming to restore visual function after photoreceptor degeneration. PMID:27199678

  7. Laser-induced retinal nerve fiber layer (NFL) damage

    NASA Astrophysics Data System (ADS)

    Zwick, Harry; Gagliano, Donald A.; Zuclich, Joseph A.; Stuck, Bruce E.; Belkin, Michael

    1995-05-01

    Retinal nerve fiber layer (NFL) damage can be induced by retinal laser photocoagulation. This type of thermal injury involves degeneration in both descending and ascending directions from the photic injury site. We have repeated early studies in evaluation of the acute phases of the injury process. Our findings indicate that the ascending or Wallerian portion of the NFL degeneration requires less time than the descending portion; an early neural debris channel occurs in close proximity to retinal vessels and appears to enter the optic disc in close proximity to the retinal vasculature. Angiography of the ascending debris sheath suggests possible capillary pattern modulation associated with this neural debris sheath. Retinal traction evident in with other acute injuries appears at 2 weeks and disappears after 8 weeks suggesting secondary control factors other than retinal hemorrhage in the development of retinal traction bands.

  8. An Unusual Case of Extensive Lattice Degeneration and Retinal Detachment.

    PubMed

    Mathew, David J; Sarma, Saurabh Kumar; Basaiawmoit, Jennifer V

    2016-07-01

    Lattice degeneration of the retina is not infrequently encountered on a dilated retinal examination and many of them do not need any intervention. We report a case of atypical lattice degeneration variant with peripheral retinal detachment. An asymptomatic 35-year-old lady with minimal refractive error was found to have extensive lattice degeneration, peripheral retinal detachment and fibrotic changes peripherally with elevation of retinal vessels on dilated retinal examination. There were also areas of white without pressure, chorioretinal scarring and retinal breaks. All the changes were limited to beyond the equator but were found to span 360 degrees. She was treated with barrage laser all around to prevent extension of the retinal detachment posteriorly. She remained stable till her latest follow-up two years after the barrage laser. This case is reported for its rarity with a discussion of the probable differential diagnoses. To the best of our knowledge, this is the first report of such findings in lattice degeneration.

  9. Retinal microglia are activated by systemic fungal infection.

    PubMed

    Maneu, Victoria; Noailles, Agustina; Megías, Javier; Gómez-Vicente, Violeta; Carpena, Núria; Gil, M Luisa; Gozalbo, Daniel; Cuenca, Nicolás

    2014-05-15

    We determined whether systemic fungal infection could cause activation of retinal microglia and, therefore, could be potentially harmful for patients with retinal degenerative diseases. Activation of retinal microglia was measured in a model of sublethal invasive candidiasis in C57BL/6J mice by confocal immunofluorescence and flow cytometry analysis, using anti-CD11b, anti-Iba1, anti-MHCII, and anti-CD45 antibodies. Systemic fungal infection causes activation of retinal microglia, with phenotypic changes in morphology, surface markers expression, and microglial relocation in retinal layers. As an excessive or prolonged microglial activation may lead to chronic inflammation with severe pathological side effects, causing or worsening the course of retinal dystrophies, a systemic infection may represent a risk factor to be considered in patients with ocular neurodegenerative diseases, such as diabetic retinopathy, glaucoma, age-related macular degeneration, or retinitis pigmentosa. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  10. Noggin 1 overexpression in retinal progenitors affects bipolar cell generation.

    PubMed

    Messina, Andrea; Bridi, Simone; Bozza, Angela; Bozzi, Yuri; Baudet, Marie-Laure; Casarosa, Simona

    2016-01-01

    Waves of Bone Morphogenetic Proteins (BMPs) and their antagonists are present during initial eye development, but their possible roles in retinogenesis are still unknown. We have recently shown that noggin 1, a BMP antagonist, renders pluripotent cells able to differentiate into retinal precursors, and might be involved in the maintenance of retinal structures in the adult vertebrate eye. Here, we report that noggin 1, differently from noggin 2 and noggin 4, is expressed during all phases of Xenopus laevis retinal development. Gain-of-function experiments by electroporation in the optic vesicle show that overexpression of noggin 1 significantly decreases the number of bipolar cells in the inner nuclear layer of the retina, without significantly affecting the generation of the other retinal cell types. Our data suggest that BMP signaling could be involved in the differentiation of retinal progenitors into specific retinal subtypes during late phases of vertebrate retinal development.

  11. Retinal Vascular Changes are a Marker for Cerebral Vascular Diseases.

    PubMed

    Moss, Heather E

    2015-07-01

    The retinal circulation is a potential marker of cerebral vascular disease because it shares origin and drainage with the intracranial circulation and because it can be directly visualized using ophthalmoscopy. Cross-sectional and cohort studies have demonstrated associations between chronic retinal and cerebral vascular disease, acute retinal and cerebral vascular disease, and chronic retinal vascular disease and acute cerebral vascular disease. In particular, certain qualitative features of retinopathy, retinal artery occlusion, and increased retinal vein caliber are associated with concurrent and future cerebrovascular events. These associations persist after accounting for confounding variables known to be disease-causing in both circulations, which supports the potential use of retinal vasculature findings to stratify individuals with regards to cerebral vascular disease risk.

  12. Retinal Artery Occlusion Secondary to Buerger's Disease (Thromboangiitis Obliterans).

    PubMed

    Eris, Erdem; Sucu, Mehmet Emin; Perente, Irfan; Alkın, Zeynep; Ozkaya, Abdullah; Tarakcioglu, Hatice Nur

    2017-01-01

    Purpose. To report a case report of one patient suffering from retinal artery occlusion secondary to Buerger's disease, in order to raise awareness to this etiology in the differential diagnosis of retinal artery occlusion. Methods. A retrospective case report of a patient with retinal artery occlusion secondary to Buerger's disease. Data retrieved from the medical records included exposure, complaints, visual acuity, clinical findings and imaging, laboratory assessment, treatment, disease course, and visual outcome. Results. Diagnosis of retinal artery occlusion secondary to Buerger's disease was established based on ruling out other causes of retinal artery occlusion. Inflammatory retinal vascular disease, permanent vision loss, and macular atrophy were shown in this case. Conclusion. The very first case of central retinal artery occlusion (CRAO) in a 64-year-old male patient with Buerger's disease. Although diagnosing CRAO based on both fundoscopic and fluorescein angiographic findings is not difficult, revealing underlying condition of CRAO occasionally could be challenging.

  13. Retinal Artery Occlusion Secondary to Buerger's Disease (Thromboangiitis Obliterans)

    PubMed Central

    Sucu, Mehmet Emin; Perente, Irfan; Tarakcioglu, Hatice Nur

    2017-01-01

    Purpose. To report a case report of one patient suffering from retinal artery occlusion secondary to Buerger's disease, in order to raise awareness to this etiology in the differential diagnosis of retinal artery occlusion. Methods. A retrospective case report of a patient with retinal artery occlusion secondary to Buerger's disease. Data retrieved from the medical records included exposure, complaints, visual acuity, clinical findings and imaging, laboratory assessment, treatment, disease course, and visual outcome. Results. Diagnosis of retinal artery occlusion secondary to Buerger's disease was established based on ruling out other causes of retinal artery occlusion. Inflammatory retinal vascular disease, permanent vision loss, and macular atrophy were shown in this case. Conclusion. The very first case of central retinal artery occlusion (CRAO) in a 64-year-old male patient with Buerger's disease. Although diagnosing CRAO based on both fundoscopic and fluorescein angiographic findings is not difficult, revealing underlying condition of CRAO occasionally could be challenging. PMID:28491481

  14. Retinal vascular changes are a marker for cerebral vascular diseases

    PubMed Central

    Moss, Heather E.

    2016-01-01

    The retinal circulation is a potential marker of cerebral vascular disease because it shares origin and drainage with the intracranial circulation and because it can be directly visualized using ophthalmoscopy. Cross sectional and cohort studies have demonstrated associations between chronic retinal and cerebral vascular disease, acute retinal and cerebral vascular disease and chronic retinal vascular disease and acute cerebral vascular disease. In particular, certain qualitative features of retinopathy, retinal artery occlusion and increased retinal vein caliber are associated with concurrent and future cerebrovascular events. These associations persist after accounting for confounding variables known to be disease-causing in both circulations, which supports the potential use of retinal vasculature findings to stratify individuals with regards to cerebral vascular disease risk. PMID:26008809

  15. Progressive outer retinal necrosis (PORN) in AIDS patients: a different appearance of varicella-zoster retinitis.

    PubMed

    Pavesio, C E; Mitchell, S M; Barton, K; Schwartz, S D; Towler, H M; Lightman, S

    1995-01-01

    Retinal infections caused by the varicella-zoster virus (VZV) have been reported in immunocompetent and immunocompromised individuals. Two cases of a VZV-related retinitis are described with the characteristic features of the recently described progressive outer retinal necrosis (PORN) syndrome. Both patients suffered from the acquired immunodeficiency syndrome (AIDS) with greatly reduced peripheral blood CD4+ T lymphocyte counts, and presented with macular retinitis without vitritis. The disease was bilateral in one case and unilateral in the other. The clinical course was rapidly progressive with widespread retinal involvement and the development of rhegmatogenous retinal detachment with complete loss of vision in the affected eyes despite intensive intravenous antiviral therapy. VZV DNA was identified in vitreous biopsies, by molecular techniques based on the polymerase chain reaction (PCR), in both patients. At present, the use of very high-dose intravenous acyclovir may be the best therapeutic option in these patients for whom the visual prognosis is poor. Intravitreal antiviral drugs could also contribute to the management of these cases.

  16. 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

  17. Retinal blood vessels are damaged in a rat model of NMDA-induced retinal degeneration.

    PubMed

    Ueda, Kaori; Nakahara, Tsutomu; Hoshino, Maya; Mori, Asami; Sakamoto, Kenji; Ishii, Kunio

    2010-11-12

    Retinal ischemia-reperfusion causes capillary degeneration but the mechanisms of damage are not well understood. The NMDA receptor plays an important role in neuronal damage after ischemia-reperfusion. Therefore, we determined whether retinal blood vessels are damaged structurally and functionally in a rat model of retinal degeneration induced by NMDA. At 7 days after a single intravitreal injection of NMDA (200nmol) into the eye, loss of retinal ganglion cells and thinning of the inner plexiform layer were observed. Endothelial cells disappeared in some regressing vessels and empty basement membrane sleeves were left as remnants of the vessels. The number of basement membrane sleeves was increased in the NMDA-treated retina and non-perfused vessels were found in the injured retina. These results indicate that retinal blood vessels are damaged in the NMDA-induced retinal degeneration model. Neuronal cells may play a role in maintaining normal structure and function of the vasculature in the retina. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  18. Visual Acuity is Related to Parafoveal Retinal Thickness in Patients with Retinitis Pigmentosa and Macular Cysts

    PubMed Central

    Brockhurst, Robert J.; Gaudio, Alexander R.; Berson, Eliot L.

    2008-01-01

    Purpose To quantify the prevalence and effect on visual acuity of macular cysts in a large cohort of patients with retinitis pigmentosa. Methods In 316 patients with typical forms of retinitis pigmentosa, we measured visual acuities with Early Treatment Diabetic Retinopathy Study (ETDRS) charts, detected macular cysts with optical coherence tomography (OCT), and quantified retinal thicknesses by OCT. We used the FREQ, LOGISTIC, and GENMOD procedures of SAS to evaluate possible risk factors for cyst prevalence and the MIXED procedure to quantify the relationships of visual acuity to retinal thickness measured at different locations within the macula. Results We found macular cysts in 28% of the patients, 40% of whom had cysts in only one eye. Macular cysts were seen most often in patients with dominant disease and not at all in patients with X-linked disease (p = 0.006). In eyes with macular cysts, multiple regression analysis revealed that visual acuity was inversely and independently related to retinal thickness at the foveal center (p = 0.038) and within a ring spanning an eccentricity of 5° to 10° from the foveal center (p = 0.004). Conclusions Macular cysts are a common occurrence in retinitis pigmentosa, especially among patients with dominantly-inherited disease. Visual acuity is influenced by edema in the parafovea, as well as in the fovea. PMID:18552390

  19. Reactive retinal microglia, neuronal survival and the formation of retinal folds and detachments

    PubMed Central

    Fischer, Andy J.; Zelinka, Christopher; Milani-Nejad, Nima

    2014-01-01

    Reactive microglia and macrophages are prevalent in damaged retinas. Accordingly, we investigate how the activation or ablation of microglia/macrophages influences the survival of neurons in the chick retina in vivo. We applied intraocular injections of interleukin 6 (IL6) to stimulate the reactivity of microglia/macrophages and clodronate-liposomes to ablate microglia/macrophages. Activation of the microglia/macrophages with IL6 delays the death of retinal neurons from N-methyl-D-aspartate (NMDA) -induced excitotoxicity. In addition, activation of microglia/macrophages combined with colchicine-mediated retinal damage diminished the survival of ganglion cells. Application of IL6 after an excitotoxic insult greatly exacerbates the damage, and causes widespread retinal detachments and folds, accompanied by accumulation of microglia/macrophages in the subretinal space. Damage-induced retinal folds and detachments were significantly reduced by the ablation of microglia/macrophages. We conclude that microglial reactivity is detrimental to the survival of ganglion cells in colchicine-damaged retinas and detrimental to the survival of photoreceptors in retinal folds. In addition, we conclude that IL6-treatment transiently protects amacrine and bipolar cells against an excitotoxic insult. We propose that suppressing reactivity of microglia/macrophages may be an effective means to lessen the damage and vision loss resulting from damage, in particular during retinal detachment injuries. PMID:25231952

  20. a Review of Retinal Prosthesis Approaches

    NASA Astrophysics Data System (ADS)

    Kien, Tran Trung; Maul, Tomas; Bargiela, Andrzej

    Age-related macular degeneration and retinitis pigmentosa are two of the most common diseases that cause degeneration in the outer retina, which can lead to several visual impairments up to blindness. Vision restoration is an important goal for which several different research approaches are currently being pursued. We are concerned with restoration via retinal prosthetic devices. Prostheses can be implemented intraocularly and extraocularly, which leads to different categories of devices. Cortical Prostheses and Optic Nerve Prostheses are examples of extraocular solutions while Epiretinal Prostheses and Subretinal Prostheses are examples of intraocular solutions. Some of the prostheses that are successfully implanted and tested in animals as well as humans can restore basic visual functions but still have limitations. This paper will give an overview of the current state of art of Retinal Prostheses and compare the advantages and limitations of each type. The purpose of this review is thus to summarize the current technologies and approaches used in developing Retinal Prostheses and therefore to lay a foundation for future designs and research directions.

  1. Retinal Imaging Techniques for Diabetic Retinopathy Screening

    PubMed Central

    Goh, James Kang Hao; Cheung, Carol Y.; Sim, Shaun Sebastian; Tan, Pok Chien; Tan, Gavin Siew Wei; Wong, Tien Yin

    2016-01-01

    Due to the increasing prevalence of diabetes mellitus, demand for diabetic retinopathy (DR) screening platforms is steeply increasing. Early detection and treatment of DR are key public health interventions that can greatly reduce the likelihood of vision loss. Current DR screening programs typically employ retinal fundus photography, which relies on skilled readers for manual DR assessment. However, this is labor-intensive and suffers from inconsistency across sites. Hence, there has been a recent proliferation of automated retinal image analysis software that may potentially alleviate this burden cost-effectively. Furthermore, current screening programs based on 2-dimensional fundus photography do not effectively screen for diabetic macular edema (DME). Optical coherence tomography is becoming increasingly recognized as the reference standard for DME assessment and can potentially provide a cost-effective solution for improving DME detection in large-scale DR screening programs. Current screening techniques are also unable to image the peripheral retina and require pharmacological pupil dilation; ultra-widefield imaging and confocal scanning laser ophthalmoscopy, which address these drawbacks, possess great potential. In this review, we summarize the current DR screening methods using various retinal imaging techniques, and also outline future possibilities. Advances in retinal imaging techniques can potentially transform the management of patients with diabetes, providing savings in health care costs and resources. PMID:26830491

  2. Novel retinal findings in peroxisomal biogenesis disorders.

    PubMed

    O'Bryhim, B E; Kozel, B A; Lueder, G T

    2018-01-29

    Peroxisomal biogenesis disorders are caused by disruption of long chain fatty acid metabolism due to mutations in PEX genes. Individuals with these disorders often have vision loss due to optic atrophy and pigmentary retinopathy. We report an unusual retinal manifestation of peroxisomal biogenesis disorder.

  3. The Retinitis Pigmentosa Student: Selected Aspects.

    ERIC Educational Resources Information Center

    Sullivan, Franklin N.

    1984-01-01

    The characteristic features of RP (retinitis pigmentosa-an untreatable conditions usually resulting in night blindness) are discussed and functioning considerations in the classroom (including the use of protective devices and mobility aids) are noted. Classroom modifications such as darklined paper and black pens are suggested. (CL)

  4. A Psychophysical Test for Retinitis Pigmentosa.

    ERIC Educational Resources Information Center

    Corwin, Thomas R; Mancini, Michael

    A new test designed to detect an hereditary eye disease called retinitis pigmentosa (RP) is described. This condition is revealed by pigmentation in the retina, but early diagnosis is difficult because the symptoms are subtle, and since it is genetically recessive it frequently occurs in families with no history of early blindness. In many cases…

  5. Unsupervised Retinal Vessel Segmentation Using Combined Filters

    PubMed Central

    Oliveira, Wendeson S.; Teixeira, Joyce Vitor; Ren, Tsang Ing; Cavalcanti, George D. C.; Sijbers, Jan

    2016-01-01

    Image segmentation of retinal blood vessels is a process that can help to predict and diagnose cardiovascular related diseases, such as hypertension and diabetes, which are known to affect the retinal blood vessels’ appearance. This work proposes an unsupervised method for the segmentation of retinal vessels images using a combined matched filter, Frangi’s filter and Gabor Wavelet filter to enhance the images. The combination of these three filters in order to improve the segmentation is the main motivation of this work. We investigate two approaches to perform the filter combination: weighted mean and median ranking. Segmentation methods are tested after the vessel enhancement. Enhanced images with median ranking are segmented using a simple threshold criterion. Two segmentation procedures are applied when considering enhanced retinal images using the weighted mean approach. The first method is based on deformable models and the second uses fuzzy C-means for the image segmentation. The procedure is evaluated using two public image databases, Drive and Stare. The experimental results demonstrate that the proposed methods perform well for vessel segmentation in comparison with state-of-the-art methods. PMID:26919587

  6. Retinal haemorrhage in infants with pertussis.

    PubMed

    Raoof, Naz; Pereira, Susana; Dai, Shuan; Neutze, Jocelyn; Grant, Cameron Charles; Kelly, Patrick

    2017-12-01

    It has been hypothesised that paroxysmal coughing in infantile pertussis (whooping cough) could produce retinal haemorrhages identical to those seen in abusive head trauma. We aimed to test this hypothesis. This is a prospective study of infants hospitalised with pertussis in Auckland, New Zealand, from 2009 to 2014. The clinical severity of pertussis was categorised. All infants recruited had retinal examination through dilated pupils by the paediatric ophthalmology service using an indirect ophthalmoscope. Forty-eight infants with pertussis, aged 3 weeks to 7 months, were examined after a mean of 18 days of coughing. Thirty-nine had severe pertussis and nine had mild pertussis. All had paroxysmal cough, and all were still coughing at the time of examination. No retinal haemorrhages were seen. We found no evidence to support the hypothesis that pertussis may cause the pattern of retinal haemorrhages seen in abusive head trauma in infants. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  7. A continuum model of retinal electrical stimulation

    NASA Astrophysics Data System (ADS)

    Joarder, Saiful A.; Abramian, Miganoosh; Suaning, Gregg J.; Lovell, Nigel H.; Dokos, Socrates

    2011-10-01

    A continuum mathematical model of retinal electrical stimulation is described. The model is represented by a passive vitreous domain, a thin layer of active retinal ganglion cell (RGC) tissue adjacent to deeper passive neural layers of the retina, the retinal pigmented epithelium (RPE) and choroid thus ending at the sclera. To validate the model, in vitro epiretinal responses to stimuli from 50 µm disk electrodes, arranged in a hexagonal mosaic, were recorded from rabbit retinas. 100 µs/phase anodic-first biphasic current pulses were delivered to the retinal surface in both the mathematical model and experiments. RGC responses were simulated and recorded using extracellular microelectrodes. The model's epiretinal thresholds compared favorably with the in vitro data. In addition, simulations showed that single-return bipolar electrodes recruited a larger area of the retina than twin-return or six-return electrodes arranged in a hexagonal layout in which a central stimulating electrode is surrounded by six, eqi-spaced returns. Simulations were also undertaken to investigate the patterns of RGC activation in an anatomically-accurate model of the retina, as well as RGC activation patterns for subretinal and suprachoroidal bipolar stimulation. This paper was originally submitted for the special issue containing contributions from the Sixth Biennial Research Congress of The Eye and the Chip.

  8. [Retinal detachment with retinoschisis--case report].

    PubMed

    Cristescu, R; Muşat, O; Toma, Oana; Coma, Corina; Gabej, Ioana; Burcea, M

    2013-01-01

    We present the case of a 43 year old patient diagnosed with rhegmatogenous retinal detachment and retinoschizis, a rare case of disease association. Surgery is recommended and we practice 23 gauge vitrectomy, laser retinopexy, criopexy in the periphery and internal heavy oil tamponade. Postoperatory evolution was favorable.

  9. Photovoltaic retinal prosthesis with high pixel density

    NASA Astrophysics Data System (ADS)

    Mathieson, Keith; Loudin, James; Goetz, Georges; Huie, Philip; Wang, Lele; Kamins, Theodore I.; Galambos, Ludwig; Smith, Richard; Harris, James S.; Sher, Alexander; Palanker, Daniel

    2012-06-01

    Retinal degenerative diseases lead to blindness due to loss of the `image capturing' photoreceptors, while neurons in the `image-processing' inner retinal layers are relatively well preserved. Electronic retinal prostheses seek to restore sight by electrically stimulating the surviving neurons. Most implants are powered through inductive coils, requiring complex surgical methods to implant the coil-decoder-cable-array systems that deliver energy to stimulating electrodes via intraocular cables. We present a photovoltaic subretinal prosthesis, in which silicon photodiodes in each pixel receive power and data directly through pulsed near-infrared illumination and electrically stimulate neurons. Stimulation is produced in normal and degenerate rat retinas, with pulse durations of 0.5-4 ms, and threshold peak irradiances of 0.2-10 mW mm-2, two orders of magnitude below the ocular safety limit. Neural responses were elicited by illuminating a single 70 µm bipolar pixel, demonstrating the possibility of a fully integrated photovoltaic retinal prosthesis with high pixel density.

  10. Photovoltaic Retinal Prosthesis with High Pixel Density

    PubMed Central

    Mathieson, Keith; Loudin, James; Goetz, Georges; Huie, Philip; Wang, Lele; Kamins, Theodore I.; Galambos, Ludwig; Smith, Richard; Harris, James S.; Sher, Alexander; Palanker, Daniel

    2012-01-01

    Retinal degenerative diseases lead to blindness due to loss of the “image capturing” photoreceptors, while neurons in the “image processing” inner retinal layers are relatively well preserved. Electronic retinal prostheses seek to restore sight by electrically stimulating surviving neurons. Most implants are powered through inductive coils, requiring complex surgical methods to implant the coil-decoder-cable-array systems, which deliver energy to stimulating electrodes via intraocular cables. We present a photovoltaic subretinal prosthesis, in which silicon photodiodes in each pixel receive power and data directly through pulsed near-infrared illumination and electrically stimulate neurons. Stimulation was produced in normal and degenerate rat retinas, with pulse durations from 0.5 to 4 ms, and threshold peak irradiances from 0.2 to 10 mW/mm2, two orders of magnitude below the ocular safety limit. Neural responses were elicited by illuminating a single 70 μm bipolar pixel, demonstrating the possibility of a fully-integrated photovoltaic retinal prosthesis with high pixel density. PMID:23049619

  11. Retinal Imaging Techniques for Diabetic Retinopathy Screening.

    PubMed

    Goh, James Kang Hao; Cheung, Carol Y; Sim, Shaun Sebastian; Tan, Pok Chien; Tan, Gavin Siew Wei; Wong, Tien Yin

    2016-02-01

    Due to the increasing prevalence of diabetes mellitus, demand for diabetic retinopathy (DR) screening platforms is steeply increasing. Early detection and treatment of DR are key public health interventions that can greatly reduce the likelihood of vision loss. Current DR screening programs typically employ retinal fundus photography, which relies on skilled readers for manual DR assessment. However, this is labor-intensive and suffers from inconsistency across sites. Hence, there has been a recent proliferation of automated retinal image analysis software that may potentially alleviate this burden cost-effectively. Furthermore, current screening programs based on 2-dimensional fundus photography do not effectively screen for diabetic macular edema (DME). Optical coherence tomography is becoming increasingly recognized as the reference standard for DME assessment and can potentially provide a cost-effective solution for improving DME detection in large-scale DR screening programs. Current screening techniques are also unable to image the peripheral retina and require pharmacological pupil dilation; ultra-widefield imaging and confocal scanning laser ophthalmoscopy, which address these drawbacks, possess great potential. In this review, we summarize the current DR screening methods using various retinal imaging techniques, and also outline future possibilities. Advances in retinal imaging techniques can potentially transform the management of patients with diabetes, providing savings in health care costs and resources. © 2016 Diabetes Technology Society.

  12. Automatic grading of retinal vessel caliber.

    PubMed

    Li, Huiqi; Hsu, Wynne; Lee, Mong Li; Wong, Tien Yin

    2005-07-01

    New clinical studies suggest that narrowing of the retinal blood vessels may be an early indicator of cardiovascular diseases. One measure to quantify the severity of retinal arteriolar narrowing is the arteriolar-to-venular diameter ratio (AVR). The manual computation of AVR is a tedious process involving repeated measurements of the diameters of all arterioles and venules in the retinal images by human graders. Consistency and reproducibility are concerns. To facilitate large-scale clinical use in the general population, it is essential to have a precise, efficient and automatic system to compute this AVR. This paper describes a new approach to obtain AVR. The starting points of vessels are detected using a matched Gaussian filter. The detected vessels are traced with the help of a combined Kalman filter and Gaussian filter. A modified Gaussian model that takes into account the central light reflection of arterioles is proposed to describe the vessel profile. The width of a vessel is obtained by data fitting. Experimental results indicate a 97.1% success rate in the identification of vessel starting points, and a 99.2% success rate in the tracking of retinal vessels. The accuracy of the AVR computation is well within the acceptable range of deviation among the human graders, with a mean relative AVR error of 4.4%. The system has interested clinical research groups worldwide and will be tested in clinical studies.

  13. Dynamic eye phantom for retinal oximetry measurements

    NASA Astrophysics Data System (ADS)

    Lemaillet, Paul; Ramella-Roman, Jessica C.

    2009-11-01

    Measurements of oxygen saturation and flow in the retina can yield information about eye health and the onset of eye pathologies such as diabetic retinopathy. Recently, we developed a multiaperture camera that uses the division of the retinal image into several wavelength-sensitive subimages to compute retinal oxygen saturation. The calibration of such instruments is particularly difficult due to the layered structure of the eye and the lack of alternative measurement techniques. For this purpose, we realize an in vitro model of the human eye composed of a lens, the retina vessel, and three layers: the choroid, the retinal pigmented epithelium, and the sclera. The retinal vessel is modeled with a microtube connected to a micropump and a hemoglobin reservoir in a closed circulatory system. Hemoglobin oxygenation in the vessel could be altered using a reversible fuel cell. The sclera is represented by a Spectralon slab. The optical properties of the other layers are mimicked using titanium dioxide as a scatterer, ink as an absorber, and epoxy as a supporting structure. The optical thickness of each layer of the eye phantom is matched to each respective eye layer.

  14. Enhanced retinal responses in Huntington's disease patients.

    PubMed

    Pearl, Jocelynn R; Heath, Laura M; Bergey, Dani E; Kelly, John P; Smith, Corrie; Laurino, Mercy Y; Weiss, Avery; Price, Nathan D; LaSpada, Albert; Bird, Thomas D; Jayadev, Suman

    2017-01-01

    Huntington's disease (HD) is a fatal progressive neurodegenerative disease characterized by chorea, cognitive impairment and psychiatric symptoms. Retinal examination of HD patients as well as in HD animal models have shown evidence of retinal dysfunction. However, a detailed retinal study employing clinically available measurement tools has not been reported to date in HD. The goal of this study was to assess retinal responses measured by electroretinogram (ERG) between HD patients and controls and evaluate any correlation between ERG measurements and stage of disease. Eighteen patients and 10 controls with inclusion criteria of ages 18-70 years (average age HD subjects: 52.1 yrs and control subjects: 51.9 yrs) were recruited for the study. Subjects with previous history of retinal or ophthalmologic disease were excluded. Retinal function was examined by full-field ERG in both eyes of each subject. Amplitudes and latencies to increasing flash intensities in both light- and dark-adaptation were measured in all subjects. Statistical analyses employed generalized estimating equations, which account for repeated measures per subject. We analyzed the b-wave amplitudes of ERG response in all flash intensities and with 30 Hz flicker stimulation. We found statistically significant increased amplitudes in HD patients compared to controls at light-adapted (photopic) 24.2 and 60.9 cd.sec/m2 intensities, dark-adapted (scotopic, red flash) 0.22 cd.sec/m2 intensity, and a trend toward significance at light-adapted 30 Hz flicker. Furthermore, we found a significant increase in light-adapted ERG response from female compared to male HD patients, but no significant difference between gender amongst controls. We also noted a positive association between number of CAG repeats and ERG response at the smallest light adapted intensity (3.1 cd.sec/m2). ERG studies revealed significantly altered retinal responses at multiple flash intensities in subjects with an HD

  15. [Genetic diagnostic testing in inherited retinal dystrophies].

    PubMed

    Kohl, S; Biskup, S

    2013-03-01

    Inherited retinal dystrophies are clinically and genetically highly heterogeneous. They can be divided according to the clinical phenotype and course of the disease, as well as the underlying mode of inheritance. Isolated retinal dystrophies (i.e., retinitis pigmentosa, Leber's congenital amaurosis, cone and cone-rod dystrophy, macular dystrophy, achromatopsia, congenital stationary nightblindness) and syndromal forms (i.e., Usher syndrome, Bardet-Biedl syndrome) can be differentiated. To date almost 180 genes and thousands of distinct mutations have been identified that are responsible for the different forms of these blinding illnesses. Until recently, there was no adequate diagnostic genetic testing available. With the development of the next generation sequencing technologies, a comprehensive genetic screening analysis for all known genes for inherited retinal dystrophies has been established at reasonable costs and in appropriate turn-around times. Depending on the primary clinical diagnosis and the presumed mode of inheritance, different diagnostic panels can be chosen for genetic testing. Statistics show that in 55-80 % of the cases the genetic defect of the inherited retinal dystrophy can be identified with this approach, depending on the initial clinical diagnosis. The aim of any genetic diagnostics is to define the genetic cause of a given illness within the affected patient and family and thereby i) confirm the clinical diagnosis, ii) provide targeted genetic testing in family members, iii) enable therapeutic intervention, iv) give a prognosis on disease course and progression and v) in the long run provide the basis for novel therapeutic approaches and personalised medicine. Georg Thieme Verlag KG Stuttgart · New York.

  16. Retinal and Choroidal Folds in Papilledema

    PubMed Central

    Sibony, Patrick A.; Kupersmith, Mark J.; Feldon, Steven E.; Wang, Jui-Kai; Garvin, Mona

    2015-01-01

    Purpose To determine the frequency, patterns, associations, and biomechanical implications of retinal and choroidal folds in papilledema due to idiopathic intracranial hypertension (IIH). Methods Retinal and choroidal folds were studied in patients enrolled in the IIH Treatment Trial using fundus photography (n = 165 study eyes) and spectral-domain optical coherence tomography (SD-OCT; n = 125). We examined the association between folds and peripapillary shape, retinal nerve fiber layer (RNFL) thickness, disc volume, Frisén grade, acuity, perimetric mean deviation, intraocular pressure, intracranial pressure, and refractive error. Results We identified three types of folds in IIH patients with papilledema: peripapillary wrinkles (PPW), retinal folds (RF), and choroidal folds (CF). Frequency, with photos, was 26%, 19%, and 1%, respectively; SD-OCT frequency was 46%, 47%, and 10%. At least one type of fold was present in 41% of patients with photos and 73% with SD-OCT. Spectral-domain OCT was more sensitive. Structural parameters related to the severity of papilledema were associated with PPW and RF, whereas anterior deformation of the peripapillary RPE/basement membrane layer was associated with CF and RF. Folds were not associated with vision loss at baseline. Conclusions Folds in papilledema are biomechanical signs of stress/strain on the optic nerve head and load-bearing structures induced by intracranial hypertension. Folds are best imaged with SD-OCT. The patterns of retinal and choroidal folds are the products of a complex interplay between the degree of papilledema and anterior deformation of the load-bearing structures (sclera and possibly the lamina cribrosa), both modulated by structural geometry and material properties of the optic nerve head. (ClinicalTrials.gov number, NCT01003639.) PMID:26335066

  17. Antibiotics Reduce Retinal Cell Survival In Vitro.

    PubMed

    Lindsey, Amy E; Townes-Anderson, Ellen

    2017-11-02

    Antibiotics such as gentamicin (an aminoglycoside) and penicillin (a beta-lactam antibiotic) are routinely used in retinal cell and explant cultures. In many cases, these in vitro systems are testing parameters regarding photoreceptor transplantation or preparing cells for transplantation. In vivo, milligram doses of gentamicin are neurotoxic to the retina. However, little is known about the effects of antibiotics to retina in vitro and whether smaller doses of gentamicin are toxic to retinal cells. To test toxicity, retinal cells were dissociated from tiger salamander, placed in culture, and treated with either 20 μg/ml gentamicin, 100 μg/ml streptomycin, 100 U/ml antibiotic/antimycotic, 0.25 μg/ml amphotericin B, or 100 U/ml penicillin G. All dosages were within manufacturer's recommended levels. Control cultures had defined medium only. Cells were fixed at 2 h or 7 days. Three criteria were used to assess toxicity: (1) survival of retinal neurons, (2) neuritic growth of photoreceptors assessed by the development of presynaptic varicosities, and (3) survival and morphology of Mueller cells. Rod cells were immunolabeled for rod opsin, Mueller cells for glial fibrillary acidic protein, and varicosities for synaptophysin. Neuronal cell density was reduced with all pharmacological treatments. The number of presynaptic varicosities was also significantly lower in both rod and cone photoreceptors in treated compared to control cultures; further, rods were more sensitive to gentamicin than cones. Penicillin G (100 U/ml) was overall the least inhibitory and amphotericin B the most toxic of all the agents to photoreceptors. Mueller cell survival was reduced with all treatments; reduced survival was accompanied by the appearance of proportionally fewer stellate and more rounded glial morphologies. These findings suggest that even microgram doses of antibiotic and antimycotic drugs can be neurotoxic to retinal cells and reduce neuritic regeneration in cell

  18. Interphotoreceptor matrix components in retinal cell transplants.

    PubMed

    Juliusson, B; Mieziewska, K; Bergström, A; Wilke, K; Van Veen, T; Ehinger, B

    1994-05-01

    To further investigate the functional potential of retinal transplants we have used immunocytochemistry to study the distribution of four different interphotoreceptor matrix (IPM)-specific components in rabbit retinal transplants. The different components were: interphotoreceptor retinoid-binding protein (IRBP), chondroitin-6-sulfate, F22 antigen and peanut agglutinin (PNA) binding structures. IRBP acts as a retinoid-transport protein between the neural retina and the retinal pigment epithelium. Chondroitin-6-sulfate is a glycosaminoglycan and a part of the insoluble IPM skeleton. The identity and role of the F22 antigen is not known. However, it is a 250 kDa protein localized to specific extracellular compartments such as teh IPM. PNA is a lectin with a high binding affinity for D-galactose-beta (1-3) N-acetyl-D-galactosamine disaccharide linkages and binds to IPM domains surrounding cones, but not rods. The transplants (15-day-old embryonic rabbit retina) were placed between the neural retina and retinal pigment epithelium in adult hosts. The transplants developed the typical rosette formations with photoreceptors toward the center. IRBP labeling was distinct in the IPM in the host retina. However, no IRBP labeling could be detected in the transplants. The chondroitin-6-sulfate and F22 antibodies strongly labeled the IPM in the host retina and corresponding structures in the center of rosettes. A cone-specific labeling with PNA could be seen in the host retina. In the transplants, however, PNA labeling appeared in association with many more photoreceptors than in the host retina. There is no previous study available on the IPM in retinal cell transplants.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Photovoltaic retinal prosthesis: implant fabrication and performance

    NASA Astrophysics Data System (ADS)

    Wang, Lele; Mathieson, K.; Kamins, T. I.; Loudin, J. D.; Galambos, L.; Goetz, G.; Sher, A.; Mandel, Y.; Huie, P.; Lavinsky, D.; Harris, J. S.; Palanker, D. V.

    2012-08-01

    The objective of this work is to develop and test a photovoltaic retinal prosthesis for restoring sight to patients blinded by degenerative retinal diseases. A silicon photodiode array for subretinal stimulation has been fabricated by a silicon-integrated-circuit/MEMS process. Each pixel in the two-dimensional array contains three series-connected photodiodes, which photovoltaically convert pulsed near-infrared light into bi-phasic current to stimulate nearby retinal neurons without wired power connections. The device thickness is chosen to be 30 µm to absorb a significant portion of light while still being thin enough for subretinal implantation. Active and return electrodes confine current near each pixel and are sputter coated with iridium oxide to enhance charge injection levels and provide a stable neural interface. Pixels are separated by 5 µm wide trenches to electrically isolate them and to allow nutrient diffusion through the device. Three sizes of pixels (280, 140 and 70 µm) with active electrodes of 80, 40 and 20 µm diameter were fabricated. The turn-on voltages of the one-diode, two-series-connected diode and three-series-connected diode structures are approximately 0.6, 1.2 and 1.8 V, respectively. The measured photo-responsivity per diode at 880 nm wavelength is ˜0.36 A W-1, at zero voltage bias and scales with the exposed silicon area. For all three pixel sizes, the reverse-bias dark current is sufficiently low (<100 pA) for our application. Pixels of all three sizes reliably elicit retinal responses at safe near-infrared light irradiances, with good acceptance of the photodiode array in the subretinal space. The fabricated device delivers efficient retinal stimulation at safe near-infrared light irradiances without any wired power connections, which greatly simplifies the implantation procedure. Presence of the return electrodes in each pixel helps to localize the current, and thereby improves resolution.

  20. Retinal Prosthesis System for Advanced Retinitis Pigmentosa: A Health Technology Assessment.

    PubMed

    2016-01-01

    Retinitis pigmentosa is a group of genetic disorders that involves the breakdown and loss of photoreceptors in the retina, resulting in progressive retinal degeneration and eventual blindness. The Argus II Retinal Prosthesis System is the only currently available surgical implantable device approved by Health Canada. It has been shown to improve visual function in patients with severe visual loss from advanced retinitis pigmentosa. The objective of this analysis was to examine the clinical effectiveness, cost-effectiveness, budget impact, and safety of the Argus II system in improving visual function, as well as exploring patient experiences with the system. We performed a systematic search of the literature for studies examining the effects of the Argus II retinal prosthesis system in patients with advanced retinitis pigmentosa, and appraised the evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria, focusing on visual function, functional outcomes, quality of life, and adverse events. We developed a Markov decision-analytic model to assess the cost-effectiveness of the Argus II system compared with standard care over a 10-year time horizon. We also conducted a 5-year budget impact analysis. We used a qualitative design and an interview methodology to examine patients' lived experience, and we used a modified grounded theory methodology to analyze information from interviews. Transcripts were coded, and themes were compared against one another. One multicentre international study and one single-centre study were included in the clinical review. In both studies, patients showed improved visual function with the Argus II system. However, the sight-threatening surgical complication rate was substantial. In the base-case analysis, the Argus II system was cost-effective compared with standard care only if willingness-to-pay was more than $207,616 per quality-adjusted life-year. The 5-year budget

  1. Retinal Prosthesis System for Advanced Retinitis Pigmentosa: A Health Technology Assessment

    PubMed Central

    Lee, Christine; Tu, Hong Anh; Weir, Mark; Holubowich, Corinne

    2016-01-01

    Background Retinitis pigmentosa is a group of genetic disorders that involves the breakdown and loss of photoreceptors in the retina, resulting in progressive retinal degeneration and eventual blindness. The Argus II Retinal Prosthesis System is the only currently available surgical implantable device approved by Health Canada. It has been shown to improve visual function in patients with severe visual loss from advanced retinitis pigmentosa. The objective of this analysis was to examine the clinical effectiveness, cost-effectiveness, budget impact, and safety of the Argus II system in improving visual function, as well as exploring patient experiences with the system. Methods We performed a systematic search of the literature for studies examining the effects of the Argus II retinal prosthesis system in patients with advanced retinitis pigmentosa, and appraised the evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria, focusing on visual function, functional outcomes, quality of life, and adverse events. We developed a Markov decision-analytic model to assess the cost-effectiveness of the Argus II system compared with standard care over a 10-year time horizon. We also conducted a 5-year budget impact analysis. We used a qualitative design and an interview methodology to examine patients’ lived experience, and we used a modified grounded theory methodology to analyze information from interviews. Transcripts were coded, and themes were compared against one another. Results One multicentre international study and one single-centre study were included in the clinical review. In both studies, patients showed improved visual function with the Argus II system. However, the sight-threatening surgical complication rate was substantial. In the base-case analysis, the Argus II system was cost-effective compared with standard care only if willingness-to-pay was more than $207,616 per quality-adjusted life

  2. 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

  3. [Preventive treatment of retinal detachment in aphakic eyes].

    PubMed

    Regnault, F; Bregeat, P

    1977-01-01

    We have examined 243 cases with retinal detachment occurring within 6 months following cataract surgery. In 92 of them retinal tear was due to lattice degeneration, in 66 to snail track degeneration and in 17 to equatorial degeneration. 290 other patients had preventive treatments. In this group, there were only 10 cases of retinal detachment. 9 out of 22 patients who had no preventive treatment suffered retinal detachments. There are two reasons for the occurrence of this retinal detachment in the 6 months following cataract surgery in eyes where retinal degenerations are found: (1) surgical trauma even with cryoextraction is responsible for traction of the vitreous base, (2) rapid disappearance of the hyaluronic acid in the aphakic vitreous is responsible for the degradation of the vitreous with formation of large zones of liquid vitreous. When adhesion between the vitreous and the retinal degeneration area remains, the traction is responsible for retinal tear or retinal detachment. The importance of the preventive treatment of retinal lesions prior to cataract surgery should be stressed.

  4. QUININE TOXICITY: MULTIMODAL RETINAL IMAGING AND ELECTRORETINOGRAPHY FINDINGS.

    PubMed

    Su, Daniel; Robson, Anthony G; Xu, David; Lightman, Susan; Sarraf, David

    2017-01-01

    To report the multimodal retinal imaging and electroretinography (ERG) findings of two cases with quinine toxicity. Retrospective case series describing the retinal imaging and ERG findings in two patients with retinal toxicity due to remote quinine exposure. Color fundus photography, fundus autofluorescence, spectral domain optical coherence tomography, and full-field ERG findings are described. Two patients with longstanding decreased vision were found to have bilateral optic disk pallor and retinal vascular attenuation indicative of chronic sequela after acute quinine toxicity. Inner retinal atrophy was identified on spectral domain optical coherence tomography, and full-field ERG was consistent with generalized inner retinal dysfunction in both patients. Fundus autofluorescence failed to demonstrate any evidence of outer retinal or retinal pigment epithelial abnormalities. Quinine toxicity may be associated with vision loss secondary to inner retinal atrophy. We report two cases with a clear history of acute quinine exposure leading to similar retinal imaging findings and distinctive ERG abnormalities. Clinicians should be aware of this uncommon condition as ingestion history may be remote.

  5. Activated retinal glia mediated axon regeneration in experimental glaucoma.

    PubMed

    Lorber, Barbara; Guidi, Alessandra; Fawcett, James W; Martin, Keith R

    2012-01-01

    Glaucoma, a leading cause of blindness, is a neurodegenerative disease characterized by progressive loss of retinal ganglion cell axons in the optic nerve and their cell bodies in the retina. Reactive retinal glial changes have been observed in glaucoma but the role of such glial changes in the pathogenesis of the condition remains unclear. In the present study we found that retinal ganglion cells in an experimental animal model of glaucoma have an increased axon regenerative potential. Regeneration of adult rat retinal ganglion cell axons after optic nerve crush was significantly increased in vivo when combined with intraocular pressure-induced experimental glaucoma. This enhanced axon regeneration response was correlated with a significant increase in activation of glial fibrillary acidic protein+retinal glia. Using a dissociated retinal ganglion cell culture model we showed that reducing the number of activated retinal glia with a glial specific toxin, α-Aminoadipic acid, significantly reduced the growth potential of retinal ganglion cells from glaucomatous rat eyes, suggesting that activated retinal glia mediate, at least in part, the growth promoting effect. This was shown to be mediated by both membrane-bound and soluble glial-derived factors. Neurotrophin and ciliary neurotrophic/leukemia inhibitory factor blockers did not affect the regenerative potential, excluding these growth factors as principal mediators of the enhanced growth response occurring in glaucomatous retinal cultures. These observations are the first to reveal that retinal ganglion cells from glaucomatous rat eyes have an enhanced regenerative capacity. Furthermore, our results suggest that activated retinal glia mediate at least part of this response. Further work to understand and enhance the regeneration-promoting effect of activated retinal glia is required to determine if this approach could be useful as part of a therapeutic strategy to encourage optic nerve regeneration in glaucoma

  6. [Bilateral retinal detachment after laser in situ keratomileusis].

    PubMed

    Kohzaki, Kenichi; Sano, Yuta; Toda, Kazushige; Mitooka, Katsuya; Nakamura, Yosuke; Kitahara, Kenji

    2004-09-01

    We report a case of bilateral retinal detachment after laser in situ keratomileusis(LASIK). A 49-year-old man received multiple laser photocoagulation for retinal lattice degeneration in both eyes and retinal tears in the left eye. He underwent bilateral LASIK in another country about 6 months after the laser photocoagulation. After the LASIK his eyes showed bilateral retinal detachment, 2 weeks later in the right eye and 5 months later in the left eye. We had to perform retinal detachment surgery four times, scleral buckling, vitrectomy, silicone oil tamponade, and removal of the silicone oil for the right eye, and one scleral buckling procedure for the left eye to achieve retinal attachment. Soon after each retinal surgery, we recognized diffuse flap edema and interface haze, three times in the right cornea and one time in the left, although this corneal flap edema subsided without any sequel. In this case, laser photocoagulation had been done several times to prevent retinal detachment in both eyes. However, retinal detachment occurred 2 weeks after LASIK in the right eye, and therefore, the LASIK procedure was considered to be the main factor influencing the development of the retinal detachment. The left eye showed retinal detachment 5 months after LASIK and we thought it possible that this retinal detachment occurred as a natural consequence of myopia. We believe it is important to hava a thorough funduscopic examination done before LASIK and it is necessary to pay attention to corneal edema and interface haze after retinal detachment surgery for post-LASIK patients.

  7. Pseudophakic retinal detachment with ruptured posterior lens capsule.

    PubMed

    Singalavanija, Apichart; Thongbun, Ornhathai; Tongsai, Sasima

    2005-11-01

    The relationship between retinal detachment and posterior lens capsule rupture in pseudophakic patients was studied. Records of patients with pseudophakic retinal detachment who were admitted to Siriraj Hospital from 1992 to 2004 were reviewed. The patients were divided into 2 main groups: 1) The study group (pseudophakic retinal detachment) 79 eyes (78 cases) which was subdivided into group 1a) pseudophakic retinal detachment with intact posterior lens capsule (50 eyes), and group 1b) pseudophakic retinal detachment with ruptured posterior lens capsule (29 eyes); 2) The control group 99 eyes (90 cases) which was subdivided into group 2a) pseudophakic patients with intact posterior lens capsule (83 eyes), and group 2b) pseudophakic patients with ruptured posterior lens capsule (16 eyes). The relationship between pseudophakic retinal detachment and posterior lens capsule rupture was analyzed by Chi-square test, and risk factors were analyzed by multiple logistic regression. Retinal detachment in pseudophakic patients was found more often in males more than in females, and the average age was 57.9 +/- 11.8 years, the retinal detachment was related to posterior lens capsule rupture (p = 0.003). Patients with pseudophakic retinal detachment with a ruptured posterior lens capsule had a risk 5.7 times greater than pseudophakic patients with an intact posterior lens capsule (adjusted Odds ratio = 5.716, 95% CI = 2.118-15.427). The present study showed that posterior lens capsule rupture increased the risk of retinal detachment. Ophthalmologists should be aware of retinal detachment development after YAG capsulotomy, especially in patients who have other risk factors such as myopia, lattice degeneration, retinal break, or previous retinal detachment surgery.

  8. Avulsed retinal vessels with and without retinal breaks--treatment and extended follow-up.

    PubMed

    Theodossiadis, G P; Koutsandrea, C N

    1985-01-01

    Between 1975 and 1984 65 cases of avulsed retinal vessels were studied. Of these 57 had avulsed vessels with retinal tear and 8 without. Of the affected eyes: 55.38 per cent were emmetropic, while myopia was present only in 29.23 per cent. Degenerative alterations (lattice-like lesions) were found in 4.61 per cent of cases. Argon laser treatment was applied in 30 cases (Group A), episcleral sponge implant with cryopexy and, in some instances, subsequent laser treatment in 34 cases (Group B). In one case vitrectomy with endodiathermy was performed. With the silastic sponge implants (Group B) we tried to obtain a high buckle in order to achieve immobilisation of the avulsed vessel through contact with the implant. The implants were applied in cases of avulsed vessels located posterior to the equator. Group B (sponge implant) showed fewer haemorrhagic recurrences after treatment than did Group A (laser application), the difference however was not statistically significant. It is also worth mentioning that in Group B the avulsed vessels which were occluded or empty of blood were to a statistically significant extent more numerous than in the laser-treated Group A. Retinal breaks with one or more avulsed retinal vessels constitute a distinct but uncommon clinical entity, which was first noted by Clark in 1962. Retinal vessels can also be avulsed by vitreous traction without a concurrent retinal tear, but can also be avulsed by vitreous traction without a concurrent retinal tear, but this condition is found much more rarely.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. TWENTY-FIVE-GAUGE PARS PLANA VITRECTOMY IN COMPLEX RETINAL DETACHMENTS ASSOCIATED WITH GIANT RETINAL TEAR.

    PubMed

    Kumar, Vinod; Kumawat, Devesh; Bhari, Anju; Chandra, Parijat

    2018-04-01

    To study the structural and functional outcomes of 25-gauge pars plana vitrectomy in giant retinal tear-associated retinal detachments. Seventeen eyes of 17 patients with giant retinal tear, who underwent 25-gauge pars plana vitrectomy over a period of 15 months at a tertiary eye care center by a single surgeon, were recruited in this retrospective interventional study. Giant retinal tears were mostly traumatic (35.3%) or associated with myopia (35.3%) and occurred in young (mean age 25.7 years) males (94.1%). Most eyes had best-corrected visual acuity ≤20/1,200 (in 82.3%), foveal detachment (in 88.2%), and proliferative vitreoretinopathy ≤Grade B (in 82.3%). The giant retinal tear extent was more than 180° in 29.4% and the fellow eye was involved in 35.2% of eyes. All eyes underwent 25-gauge pars plana vitrectomy with encircling band in 41.1%, perfluorocarbon liquid use in 82.3%, and endotamponade with sulphur hexafluoride (23.6%) or silicone oil (76.4%). At mean follow-up of 10.2 months, reattachment rate was 88.2%. Only 35.2% of eyes achieved final visual acuity ≥20/80 with a cause of poor vision being cataract, secondary glaucoma, macular pucker, and corneal edema. Twenty-five-gauge pars plana vitrectomy can achieve excellent attachment rates in eyes with giant retinal tear-associated retinal detachment. It can be as efficient as larger-gauge vitrectomy, at the same time retaining all advantages of smaller-gauge surgery.

  10. HIF-1α stabilization reduces retinal degeneration in a mouse model of retinitis pigmentosa.

    PubMed

    Olivares-González, Lorena; Martínez-Fernández de la Cámara, Cristina; Hervás, David; Millán, José María; Rodrigo, Regina

    2018-05-01

    Retinitis pigmentosa (RP) is a group of inherited retinal dystrophies characterized by progressive and irreversible loss of vision due to rod and cone degeneration. Evidence suggests that an inappropriate oxygen level could contribute to its pathogenesis. Rod cell death could increase oxygen concentration, reduce hypoxia-inducible factor 1 (HIF-1α) and contribute to cone cell death. The purposes of this study were: 1) to analyze the temporal profile of HIF-1α, its downstream effectors VEGF, endothelin-1 (ET-1), iNOS, and glucose transporter 1 (GLUT1), and neuroinflammation in retinas of the murine model of rd10 ( retinal degeneration 10) mice with RP; 2) to study oxygen bioavailability in these retinas; and 3) to investigate how stabilizing HIF-1α proteins with dimethyloxaloglycine (DMOG), a prolyl hydroxylase inhibitor, affects retinal degeneration, neuroinflammation, and antioxidant response in rd10 mice. A generalized down-regulation of HIF-1α and its downstream targets was detected in parallel with reactive gliosis, suggesting high oxygen levels during retinal degeneration. At postnatal d 18, DMOG treatment reduced photoreceptor cell death and glial activation. In summary, retinas of rd10 mice seem to be exposed to a hyperoxic environment even at early stages of degeneration. HIF-1α stabilization could have a temporal neuroprotective effect on photoreceptor cell survival, glial activation, and antioxidant response at early stages of RP.-Olivares-González, L., Martínez-Fernández de la Cámara, C., Hervás, D., Millán, J. M., Rodrigo, R. HIF-1α stabilization reduces retinal degeneration in a mouse model of retinitis pigmentosa.

  11. Changes in retinal oxygen saturation, choroidal thickness, and retinal nerve fibre layer.

    PubMed

    Du, Shaolin; Gao, Xinbo; Zhang, Xiulan; Wang, Jiawei; Huang, Wenbin; Zhou, Minwen; Wang, Wei; Li, Xingyi; Zhang, Yichi; Lam, Dennis S C

    2015-04-01

    To investigate the changes of retinal oxygen saturation (Sat O2) concentrations, choroidal thickness (CT), and retinal nerve fibre layer (RNFL) in eyes with trabeculectomy-required acute primary angle closure (APAC). Prospective, longitudinal study. Twenty-three eyes with trabeculectomy-required APAC were recruited. Retinal oximetry was performed at postoperative day one and again at approximately 1 month. CT and the RNFL were tested on the same day. A paired t test and Pearson correlation were used for analysis. Mean Sat O2 increased in retinal arterioles from 88.74% ± 14.36% at postoperative day 1 to 96.61% ± 18.42% at 1 month (p = 0.049). The mean diameter of the arterioles was statistically different between postoperative day 1 and 1 month (p = 0.044), as was the mean diameter of the venules (p = 0.027). APAC eyes at postoperative 1 month had a thinner mean CT, compared with day 1 (p = 0.002). No significant difference was found in the RNFL between postoperative day 1 and 1 month (p > 0.05). The Sat O2 in retinal arterioles correlated with the mean diameter of the arterioles at postoperative day 1 (r = -0.482, p = 0.020) and at 1 month (r = -0.463, p = 0.026). No significant correlation was found between retinal Sat O2 and other parameters. Increased Sat O2 in retinal arterioles, changed vessel diameter, and thinner CT from postoperative day 1 to 1 month suggest gradual recovery from APAC. However, the different pathophysiologies for APAC still need further study to prove. Copyright © 2015 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

  12. Variable involvement of the perivascular retinal tissue in carbonic anhydrase inhibitor induced relaxation of porcine retinal arterioles in vitro.

    PubMed

    Kehler, Anne Katrine; Holmgaard, Kim; Hessellund, Anders; Aalkjaer, Christian; Bek, Toke

    2007-10-01

    Inhibition of carbonic anhydrase in the eye is an important treatment modality for reducing the intraocular pressure in glaucoma. However, evidence suggests that carbonic anhydrase inhibition also exerts a relaxing effect on the vessels in the optic nerve, and it has been suggested that this vasorelaxing effect is a result of an interplay between the perivascular tissue and constituents in the retinal vascular wall. However, the exact nature of this interplay is unknown. Isolated porcine retinal arterioles and arterioles with preserved perivascular retinal tissue were mounted in a myograph. After precontraction with the prostaglandin analogue U46619, the vasorelaxing effect of the carbonic anhydrase inhibitors methyl bromopyruvate, ethyl bromopyruvate, acetazolamide, and dorzolamide were studied. All the examined carbonic anhydrase inhibitors induced a significant relaxation of retinal arterioles. There was no significant difference between the effect of the different carbonic anhydrase inhibitors in the presence of perivascular retinal tissue. However, in the isolated retinal arterioles the vasodilating effect of dorzolamide was significantly lower, and the vasodilating effect of acetazolamide almost disappeared. A further elucidation of the mechanisms of action of carbonic anhydrase-induced dilation of retinal arterioles may contribute to a better understanding of the regulation of retinal blood flow. The perivascular retinal tissue may play a significant role in diameter control of retinal arterioles.

  13. Retinal area detector from scanning laser ophthalmoscope (SLO) images for diagnosing retinal diseases.

    PubMed

    Haleem, Muhammad Salman; Han, Liangxiu; van Hemert, Jano; Li, Baihua; Fleming, Alan

    2015-07-01

    Scanning laser ophthalmoscopes (SLOs) can be used for early detection of retinal diseases. With the advent of latest screening technology, the advantage of using SLO is its wide field of view, which can image a large part of the retina for better diagnosis of the retinal diseases. On the other hand, during the imaging process, artefacts such as eyelashes and eyelids are also imaged along with the retinal area. This brings a big challenge on how to exclude these artefacts. In this paper, we propose a novel approach to automatically extract out true retinal area from an SLO image based on image processing and machine learning approaches. To reduce the complexity of image processing tasks and provide a convenient primitive image pattern, we have grouped pixels into different regions based on the regional size and compactness, called superpixels. The framework then calculates image based features reflecting textural and structural information and classifies between retinal area and artefacts. The experimental evaluation results have shown good performance with an overall accuracy of 92%.

  14. Evolution of outer retinal folds occurring after vitrectomy for retinal detachment repair.

    PubMed

    dell'Omo, Roberto; Tan, H Stevie; Schlingemann, Reinier O; Bijl, Heico M; Lesnik Oberstein, Sarit Y; Barca, Francesco; Mura, Marco

    2012-12-03

    To assess the evolution of outer retinal folds (ORFs) occurring after repair of rhegmatogenous retinal detachment (RRD) using spectral domain-optical coherence tomography (sd-OCT) and fundus autofluorescence (FAF), and to discuss their pathogenesis. Twenty patients were operated on with 25-gauge pars plana vitrectomy and 20% sulfur hexafluoride gas injection for primary macula-off RRD repair and were followed prospectively. Sd-OCT and FAF images were recorded at 1, 3 and 6 months postoperatively. ORFs appeared on sd-OCT as hyperreflective lesions consisting of folded inner segment/outer segment of photoreceptors band and external limiting membrane band. Corresponding lines of increased or decreased autofluorescence were observed on FAF. Over the follow-up, the thick hypoautofluorescent lines progressively evolved to thick hyperautofluorescent lines and to thin hyperautofluorescent lines and eventually disappeared. Concomitantly, OCT scans revealed that the corresponding hyperreflective lesions decreased in number, height, and size. In six cases FAF assessment at month 6 was precluded by cataract development. ORFS tend to resolve spontaneously within a few months from operation leaving no or subtle abnormalities at the level of the outer retinal layers. OCT is superior to FAF to follow the evolution of orfs in phakic eyes. The following factors might be involved in ORFS pathogenesis: structural changes occurring in the detached retina, residual pockets of subretinal fluid after retinal reattachment, intravitreal gas, unintentional retinal translocation, and intraoperative or perioperative hypotony.

  15. The development of melanopsin-containing retinal ganglion cells in mice with early retinal degeneration.

    PubMed

    Ruggiero, Linda; Allen, Charles N; Brown, R Lane; Robinson, David W

    2009-01-01

    In mammals, the neuronal pathways by which rod and cone photoreceptors mediate vision have been well documented. The roles that classical photoreceptors play in photoentrainment, however, have been less clear. In mammals, intrinsically photosensitive retinal ganglion cells (ipRGCs) that express the photopigment melanopsin project directly to the suprachiasmatic nucleus of the hypothalamus, the site of the circadian clock, and thereby contribute to non-image-forming responses to light. Classical photoreceptors are not necessary for photoentrainment as loss of rods and cones does not eliminate light entrainment. Conflicting evidence arose, however, when attenuated phase-shifting responses were observed in the retinal-degenerate CBA/J mouse. In this study, we examined the time course of retinal degeneration in CBA/J mice and used these animals to determine if maturation of the outer retina regulates the morphology, number and distribution of ipRGCs. We also examined whether degeneration during the early development of the outer retina can alter the function of the adult circadian system. We report that dendritic stratification and distribution of ipRGCs was unaltered in mice with early retinal degeneration, suggesting that normal development of the outer retina was not necessary for these processes. We found, however, that adult CBA/J mice have greater numbers of ipRGCs than controls, implicating a role for the outer retinal photoreceptors in regulating developmental cell death of ipRGCs.

  16. RETINAL PIGMENT EPITHELIAL ATROPHY AFTER ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR INJECTIONS FOR RETINAL ANGIOMATOUS PROLIFERATION.

    PubMed

    Hata, Masayuki; Yamashiro, Kenji; Oishi, Akio; Ooto, Sotaro; Tamura, Hiroshi; Miyata, Manabu; Ueda-Arakawa, Naoko; Kuroda, Yoshimasa; Takahashi, Ayako; Tsujikawa, Akitaka; Yoshimura, Nagahisa

    2017-11-01

    To investigate the incidence rate and risk factors for development of retinal pigment epithelial (RPE) atrophy during anti-vascular endothelial growth factor (anti-VEGF) treatment for retinal angiomatous proliferation. This study included 46 eyes with treatment-naive retinal angiomatous proliferation. All patients were treated with ranibizumab or aflibercept injections. Color fundus photography, spectral-domain optical coherence tomography, and fundus autofluorescence were evaluated for RPE atrophy diagnosis. Baseline characteristics and gene polymorphisms of ARMS2 A69S, and CFH I62V were analyzed for association with development and progression of RPE atrophy. Among 21 eyes treated with ranibizumab without preexisting RPE atrophy at baseline, 5 eyes (23.8%) developed RPE atrophy at 12 months. Among 20 eyes treated with aflibercept without preexisting RPE atrophy at baseline, 10 eyes (50.0%) developed RPE atrophy at 12 months. Refractile drusen at baseline was associated with RPE atrophy development at 12 months (P = 0.014), and the progression rate of RPE atrophy area was negatively correlated with subfoveal choroidal thickness at baseline (R = -0.595, P = 0.019). Gene polymorphisms were not associated with RPE atrophy. Retinal pigment epithelial atrophy developed in 36.6% during 12 months after anti-VEGF treatment for retinal angiomatous proliferation. The presence of refractile drusen at baseline was identified as a novel significant risk factor for RPE atrophy development.

  17. Retinal ganglion cell neuroprotection by an angiotensin II blocker in an ex vivo retinal explant model.

    PubMed

    White, Andrew J R; Heller, Janosch P; Leung, Johahn; Tassoni, Alessia; Martin, Keith R

    2015-12-01

    An ex vivo organotypic retinal explant model was developed to examine retinal survival mechanisms relevant to glaucoma mediated by the renin angiotensin system in the rodent eye. Eyes from adult Sprague Dawley rats were enucleated immediately post-mortem and used to make four retinal explants per eye. Explants were treated either with irbesartan (10 µM), vehicle or angiotensin II (2 μM) for four days. Retinal ganglion cell density was estimated by βIII tubulin immunohistochemistry. Live imaging of superoxide formation with dihydroethidium (DHE) was performed. Protein expression was determined by Western blotting, and mRNA expression was determined by RT-PCR. Irbesartan (10 µM) almost doubled ganglion cell survival after four days. Angiotensin II (2 µM) reduced cell survival by 40%. Sholl analysis suggested that irbesartan improved ganglion cell dendritic arborisation compared to control and angiotensin II reduced it. Angiotensin-treated explants showed an intense DHE fluorescence not seen in irbesartan-treated explants. Analysis of protein and mRNA expression determined that the angiotensin II receptor At1R was implicated in modulation of the NADPH-dependent pathway of superoxide generation. Angiotensin II blockers protect retinal ganglion cells in this model and may be worth further investigation as a neuroprotective treatment in models of eye disease. © The Author(s) 2015.

  18. Human retinal microvascular imaging using adaptive optics scanning light ophthalmoscopy.

    PubMed

    Chui, Toco Y P; Mo, Shelley; Krawitz, Brian; Menon, Nikhil R; Choudhury, Nadim; Gan, Alexander; Razeen, Moataz; Shah, Nishit; Pinhas, Alexander; Rosen, Richard B

    2016-01-01

    Retinal microvascular imaging is an especially promising application of high resolution imaging since there are increasing options for therapeutic intervention and need for better structural and functional biomarkers to characterize ocular and systemic vascular diseases. Adaptive optics scanning light ophthalmoscopy (AOSLO) is an emerging technology for improving in vivo imaging of the human retinal microvasculature, allowing unprecedented visualization of retinal microvascular structure, measurements of blood flow velocity, and microvascular network mapping. This high resolution imaging technique shows significant potential for studying physiological and pathological conditions of the retinal microvasculature noninvasively. This review will briefly summarize the abilities of in vivo human retinal microvasculature imaging in healthy controls, as well as patients with diabetic retinopathy, retinal vein occlusion, and sickle cell retinopathy using AOSLO and discuss its potential contribution to scientific research and clinical applications.

  19. Adaptive Optics Technology for High-Resolution Retinal Imaging

    PubMed Central

    Lombardo, Marco; Serrao, Sebastiano; Devaney, Nicholas; Parravano, Mariacristina; Lombardo, Giuseppe

    2013-01-01

    Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of optical aberrations. The direct visualization of the photoreceptor cells, capillaries and nerve fiber bundles represents the major benefit of adding AO to retinal imaging. Adaptive optics is opening a new frontier for clinical research in ophthalmology, providing new information on the early pathological changes of the retinal microstructures in various retinal diseases. We have reviewed AO technology for retinal imaging, providing information on the core components of an AO retinal camera. The most commonly used wavefront sensing and correcting elements are discussed. Furthermore, we discuss current applications of AO imaging to a population of healthy adults and to the most frequent causes of blindness, including diabetic retinopathy, age-related macular degeneration and glaucoma. We conclude our work with a discussion on future clinical prospects for AO retinal imaging. PMID:23271600

  20. Can Commercially Available Handheld Retinal Cameras Effectively Screen Diabetic Retinopathy?

    PubMed

    Cuadros, Jorge; Bresnick, George

    2017-01-01

    Organizations that care for people with diabetes have increasingly adopted telemedicine-based diabetic retinopathy screening (TMDRS) as a way to increase adherence to recommended retinal exams. Recently, handheld retinal cameras have emerged as a low-cost, lightweight alternative to traditional bulky tabletop retinal cameras. Few published clinical trials have been performed on handheld retinal cameras. Peer-reviewed articles about commercially available handheld retinal cameras have concluded that they are a usable alternative for TMDRS, however, the clinical results presented in these articles do not meet criteria published by the United Kingdom Diabetic Eye Screening Programme and the American Academy of Ophthalmology. The future will likely remedy the shortcomings of currently available handheld retinal cameras, and will create more opportunities for preventing diabetic blindness.

  1. Can Commercially Available Handheld Retinal Cameras Effectively Screen Diabetic Retinopathy?

    PubMed Central

    Cuadros, Jorge; Bresnick, George

    2016-01-01

    Organizations that care for people with diabetes have increasingly adopted telemedicine-based diabetic retinopathy screening (TMDRS) as a way to increase adherence to recommended retinal exams. Recently, handheld retinal cameras have emerged as a low-cost, lightweight alternative to traditional bulky tabletop retinal cameras. Few published clinical trials have been performed on handheld retinal cameras. Peer-reviewed articles about commercially available handheld retinal cameras have concluded that they are a usable alternative for TMDRS, however, the clinical results presented in these articles do not meet criteria published by the United Kingdom Diabetic Eye Screening Programme and the American Academy of Ophthalmology. The future will likely remedy the shortcomings of currently available handheld retinal cameras, and will create more opportunities for preventing diabetic blindness. PMID:28264174

  2. Contribution of Microglia-Mediated Neuroinflammation to Retinal Degenerative Diseases

    PubMed Central

    Madeira, Maria H.; Boia, Raquel; Santos, Paulo F.; Ambrósio, António F.; Santiago, Ana R.

    2015-01-01

    Retinal degenerative diseases are major causes of vision loss and blindness worldwide and are characterized by chronic and progressive neuronal loss. One common feature of retinal degenerative diseases and brain neurodegenerative diseases is chronic neuroinflammation. There is growing evidence that retinal microglia, as in the brain, become activated in the course of retinal degenerative diseases, having a pivotal role in the initiation and propagation of the neurodegenerative process. A better understanding of the events elicited and mediated by retinal microglia will contribute to the clarification of disease etiology and might open new avenues for potential therapeutic interventions. This review aims at giving an overview of the roles of microglia-mediated neuroinflammation in major retinal degenerative diseases like glaucoma, age-related macular degeneration, and diabetic retinopathy. PMID:25873768

  3. Cellular Reparative Mechanisms of Mesenchymal Stem Cells for Retinal Diseases

    PubMed Central

    Ding, Suet Lee Shirley; Kumar, Suresh; Mok, Pooi Ling

    2017-01-01

    The use of multipotent mesenchymal stem cells (MSCs) has been reported as promising for the treatment of numerous degenerative disorders including the eye. In retinal degenerative diseases, MSCs exhibit the potential to regenerate into retinal neurons and retinal pigmented epithelial cells in both in vitro and in vivo studies. Delivery of MSCs was found to improve retinal morphology and function and delay retinal degeneration. In this review, we revisit the therapeutic role of MSCs in the diseased eye. Furthermore, we reveal the possible cellular mechanisms and identify the associated signaling pathways of MSCs in reversing the pathological conditions of various ocular disorders such as age-related macular degeneration (AMD), retinitis pigmentosa, diabetic retinopathy, and glaucoma. Current stem cell treatment can be dispensed as an independent cell treatment format or with the combination of other approaches. Hence, the improvement of the treatment strategy is largely subjected by our understanding of MSCs mechanism of action. PMID:28788088

  4. Contribution of microglia-mediated neuroinflammation to retinal degenerative diseases.

    PubMed

    Madeira, Maria H; Boia, Raquel; Santos, Paulo F; Ambrósio, António F; Santiago, Ana R

    2015-01-01

    Retinal degenerative diseases are major causes of vision loss and blindness worldwide and are characterized by chronic and progressive neuronal loss. One common feature of retinal degenerative diseases and brain neurodegenerative diseases is chronic neuroinflammation. There is growing evidence that retinal microglia, as in the brain, become activated in the course of retinal degenerative diseases, having a pivotal role in the initiation and propagation of the neurodegenerative process. A better understanding of the events elicited and mediated by retinal microglia will contribute to the clarification of disease etiology and might open new avenues for potential therapeutic interventions. This review aims at giving an overview of the roles of microglia-mediated neuroinflammation in major retinal degenerative diseases like glaucoma, age-related macular degeneration, and diabetic retinopathy.

  5. Mechanism by which Untwisting of Retinal Leads to Productive Bacteriorhodopsin Photocycle States

    SciTech Connect

    Wolter, Tino; Elstner, Marcus; Fischer, Stefan

    2014-01-01

    Relaxation of the twisted-retinal photoproduct state triggers proton-coupled reaction cycle in retinal proteins. A key open question is whether the retinal relaxation path is governed by the intrinsic torsional properties of the retinal or rather by the interactions of the retinal with protein and water groups, given the crowded protein environments in which the retinal resides. We address this question by performing systematic quantum mechanical/molecular mechanical molecular dynamics computations of retinal dynamics in bacteriorhodopsin at different temperatures, reaction path computations, and assessment of the vibrational fingerprints of the retinal molecule. Our results demonstrate a complex dependence of the retinal dynamicsmore » and preferred geometry on temperature. As the temperature increases, the retinal dihedral angle samples values largely determined by its internal conformational energy. The protein environment shapes the energetics of retinal relaxation and provides hydrogen-bonding partners that stabilize the retinal geometry.« less

  6. Unilateral retinitis pigmentosa. A case report.

    PubMed

    Nazar, C; Feldman, M; González, R; Espinoza, R

    2017-06-01

    A 27-year-old woman with a history of nyctalopia and constriction of visual field of the right eye. The ophthalmological examination showed a visual field and electroretinogram that were compatible with unilateral retinitis pigmentosa (RP). After a one year follow-up, the unilateral condition remained. Unilateral retinitis pigmentosa is a rare condition, with a frequency between 0.2%-5% of the RP. It mainly affects women and older age groups than bilateral RP. For a definitive diagnosis, it is necessary to have a funduscopy and electroretinogram (ERG) altered unilaterally, and exclude infectious, inflammatory, and vascular causes. Copyright © 2016 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.

  7. Presumed solitary circumscribed retinal astrocytic proliferation.

    PubMed

    Asensio-Sánchez, V M; Díaz-Cabanas, L

    2017-03-01

    Presumed solitary circumscribed retinal astrocytic proliferation (PSCRAP) is a small defined solitary lesion. A 58-year-old man had an opaque yellow retinal lesion inferonasal to the optic disc. Fluorescein angiography showed mild early hyperfluorescence and late fluorescence. Ultrasound showed no calcification. Autofluorescence disclosed moderate hyperautofluorescence. Optical coherence tomography showed the mass with a snowball configuration and a smooth surface. More than one year later, the lesion was unchanged. PSCRAP is a benign stable lesion. The main importance lies in its differentiation from well-circumscribed yellow-white lesions of the retina. Copyright © 2016 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.

  8. Bilateral Giant Retinal Tear and Sequential Vitrectomy.

    PubMed

    Mustapha, Mushawiahti; Roufail Franzco, Edward

    2017-01-01

    To describe the excellent outcome of surgery for bilateral giant retinal tears (GRTs) with better options of endotamponade. This is a case report of a 62-year-old man who presented with bilateral GRTs and associated retinal detachment. The tear in the right eye was supero-temporal and silicone oil was used as an endotamponade. The tear in the left eye was infero-temporal and perfluorocarbon liquid was used as an endotamponade. The outcome at 6 months after surgery was excellent with visual acuities of 6/6 in both eyes. Improved availability of endotamponade agents allows repair of bilateral GRTs to be done at the same time, with good surgical outcomes.

  9. Bilateral Giant Retinal Tear and Sequential Vitrectomy

    PubMed Central

    Mustapha, Mushawiahti; Roufail Franzco, Edward

    2017-01-01

    Purpose To describe the excellent outcome of surgery for bilateral giant retinal tears (GRTs) with better options of endotamponade. Methods This is a case report of a 62-year-old man who presented with bilateral GRTs and associated retinal detachment. The tear in the right eye was supero-temporal and silicone oil was used as an endotamponade. The tear in the left eye was infero-temporal and perfluorocarbon liquid was used as an endotamponade. Results The outcome at 6 months after surgery was excellent with visual acuities of 6/6 in both eyes. Conclusion Improved availability of endotamponade agents allows repair of bilateral GRTs to be done at the same time, with good surgical outcomes. PMID:28924443

  10. New imaging techniques in retinal vasculitis.

    PubMed

    Mesquida, Marina; Llorens, Víctor; Adán, Alfredo

    2017-09-20

    The term retinal vasculitis (RV) encompasses a heterogeneous group of sight-threatening conditions that are included in the intraocular inflammatory diseases that affect the posterior segment of the eye. Based on the nature of the inflammatory process, RV are classified into predominantly inflammatory or ischaemic (occlusive RV). The diagnosis is clinical and the aetiology can be infectious or non-infectious (immune-mediated). RV can be an isolated ocular syndrome or be associated with a systemic disease, of which they can represent the first manifestation. New retinal imaging techniques such as ultra-wide field fluorescein angiography and optical coherence tomography angiography will help us classify the RV and aid the diagnostic process, which can be challenging and require a multidisciplinary approach. Therefore, clinical knowledge of RV is essential for prompt diagnosis and to establish the appropriate treatment. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

  11. Adaptive Optics Imaging in Retinal Vasculitis.

    PubMed

    Mahendradas, Padmamalini; Vala, Ruchi; Kawali, Ankush; Akkali, Mukund C; Shetty, Rohit

    2016-12-23

    To study the sheathing of retinal vasculitis in various systemic autoimmune diseases using adaptive optics imaging (AOI). Prospective, observational case series with six patients: Behçet disease (n = 1); systemic lupus erythematosus (n = 1); idiopathic retinal vasculitis (n = 2); granulomatosis with polyangiitis (n = 1); and Takayasu aorta arteritis (n = 1). Fundus photograph (FP), fundus fluorescein angiography (FFA) were done in all cases at presentation. Using the Image J software, perivascular sheathing and wall-to-wall diameter of the vessel involved were measured on AOI at time of presentation and on follow-up. AOI was able to pick the pipe-stem sheathing in SLE and IRV(I) and parallel sheathing in rest, which correlated with FP and FFA. Moreover, the decrease and a complete resolution in the sheathing were also noted by AOI on follow-up. AOI can be used as an additional investigative tool for diagnosis and to monitor the disease course during the treatment.

  12. Tenascins in Retinal and Optic Nerve Neurodegeneration

    PubMed Central

    Reinhard, Jacqueline; Roll, Lars; Faissner, Andreas

    2017-01-01

    Tenascins represent key constituents of the extracellular matrix (ECM) with major impact on central nervous system (CNS) development. In this regard, several studies indicate that they play a crucial role in axonal growth and guidance, synaptogenesis and boundary formation. These functions are not only important during development, but also for regeneration under several pathological conditions. Additionally, tenascin-C (Tnc) represents a key modulator of the immune system and inflammatory processes. In the present review article, we focus on the function of Tnc and tenascin-R (Tnr) in the diseased CNS, specifically after retinal and optic nerve damage and degeneration. We summarize the current view on both tenascins in diseases such as glaucoma, retinal ischemia, age-related macular degeneration (AMD) or diabetic retinopathy. In this context, we discuss their expression profile, possible functional relevance, remodeling of the interacting matrisome and tenascin receptors, especially under pathological conditions. PMID:29109681

  13. Retinal Detachment due to CrossFit Training Injury.

    PubMed

    Joondeph, Stephanie A; Joondeph, Brian C

    2013-01-01

    The purpose of this paper is to describe a traumatic retinal detachment occurring as a result of CrossFit training using an elastic exercise band. The patient sustained an ocular injury from an elastic band during CrossFit training, resulting in a giant retinal dialysis and retinal detachment, which were successfully repaired. Trainers and athletes need to be aware of the potential for ocular injury from elastic exercise bands and take appropriate precautions.

  14. Retinal Detachment due to CrossFit Training Injury

    PubMed Central

    Joondeph, Stephanie A.; Joondeph, Brian C.

    2013-01-01

    The purpose of this paper is to describe a traumatic retinal detachment occurring as a result of CrossFit training using an elastic exercise band. The patient sustained an ocular injury from an elastic band during CrossFit training, resulting in a giant retinal dialysis and retinal detachment, which were successfully repaired. Trainers and athletes need to be aware of the potential for ocular injury from elastic exercise bands and take appropriate precautions. PMID:24106626

  15. Progressive Outer Retinal Necrosis and Immunosuppressive Therapy in Myasthenia Gravis

    PubMed Central

    Coisy, Solène; Ebran, Jean-Marc; Milea, Dan

    2014-01-01

    Introduction Progressive outer retinal necrosis (PORN) is a rare but devastating infectious retinitis associated with varicella zoster virus (VZV) and responsible for severe visual loss. Case Report A 59-year-old man treated for generalized myasthenia with oral azathioprine and prednisone presented with severe unilateral necrotizing retinitis. Polymerase chain reaction of the aqueous and vitreous humors was diagnostic for VZV PORN. Conclusion VZV PORN is a severe potential ocular complication of immunosuppression, prompting urgent diagnosis and appropriate treatment. PMID:24926266

  16. Progressive outer retinal necrosis and immunosuppressive therapy in myasthenia gravis.

    PubMed

    Coisy, Solène; Ebran, Jean-Marc; Milea, Dan

    2014-01-01

    Progressive outer retinal necrosis (PORN) is a rare but devastating infectious retinitis associated with varicella zoster virus (VZV) and responsible for severe visual loss. A 59-year-old man treated for generalized myasthenia with oral azathioprine and prednisone presented with severe unilateral necrotizing retinitis. Polymerase chain reaction of the aqueous and vitreous humors was diagnostic for VZV PORN. VZV PORN is a severe potential ocular complication of immunosuppression, prompting urgent diagnosis and appropriate treatment.

  17. Restoration of the Retinal Structure and Function after Injury

    DTIC Science & Technology

    2014-04-01

    head impact may result in traumatic retinopathy due to damage of retinal pigment epithelium (RPE) and photoreceptors, leading to loss of sight...and the loss of sight is permanent. This study is focused on development of the animal model of traumatic retinopathy and evaluation of the role of...constructive retinal plasticity in elimination or reduction of retinal scotomata and scarring. We established a model of traumatic retinopathy using

  18. Scleral buckling for retinal detachment in patients with retinoblastoma

    SciTech Connect

    Buzney, S.M.; Pruett, R.C.; Regan, C.D.

    1984-10-15

    Three children (two girls and one boy) with bilateral retinoblastoma each developed a presumed rhegmatogenous retinal detachment in one eye. All three eyes had previously received radiation and cryotherapy. In each case the retinal detachment responded promptly to conventional surgical methods via scleral buckling in the area of treated retinoblastoma and presumed retinal break. All three eyes have retained useful vision for follow-up periods of 3.5 to 12 years.

  19. Avascular Retinal Findings in a Child With Achondroplasia.

    PubMed

    Hua, Hong-Uyen T; Tran, Kimberly D; Medina, Carlos A; Fallas, Brenda; Negron, Cathy; Berrocal, Audina M

    2017-03-01

    The authors present clinical and angiographic findings in a 12-year-old girl with achondroplasia who presented with bilateral retinal peripheral nonperfusion and unilateral rhegmatogenous retinal detachment, which has not been previously described in achondroplasia. This report contributes incremental knowledge regarding aberrant retinal vascular phenomena observed in pediatric disease states and implicates the possible role of mutations in the FGFR3 gene in peripheral vascular abnormalities. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:272-274.]. Copyright 2017, SLACK Incorporated.

  20. Human bone marrow mesenchymal stem cells for retinal vascular injury.

    PubMed

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

    2017-09-01

    To examine the potential of intravitreally implanted human bone marrow-derived mesenchymal stem cells (BMSCs) to affect vascular repair and the blood-retina barrier in mice and rats with oxygen-induced retinopathy, diabetic retinopathy or retinal ischaemia-reperfusion damage. Three study groups (oxygen-induced retinopathy group: 18 C57BL/6J mice; diabetic retinopathy group: 15 rats; retinal ischaemia-reperfusion model: 18 rats) received BMSCs injected intravitreally. Control groups (oxygen-induced retinopathy group: 12 C57BL/6J mice; diabetic retinopathy group: 15 rats; retinal ischaemia-reperfusion model: 18 rats) received an intravitreal injection of phosphate-buffered saline. We applied immunohistological techniques to measure retinal vascularization, spectroscopic measurements of intraretinally extravasated fluorescein-conjugated dextran to quantify the blood-retina barrier breakdown, and histomorphometry to assess retinal thickness and retinal ganglion cell count. In the oxygen-induced retinopathy model, the study group with intravitreally injected BMSCs as compared with the control group showed a significantly (p = 0.001) smaller area of retinal neovascularization. In the diabetic retinopathy model, study group and control group did not differ significantly in the amount of intraretinally extravasated dextran. In the retinal ischaemia-reperfusion model, on the 7th day after retina injury, the retina was significantly thicker in the study group than in the control group (p = 0.02), with no significant difference in the retinal ganglion cell count (p = 0.36). Intravitreally implanted human BMSCs were associated with a reduced retinal neovascularization in the oxygen-induced retinopathy model and with a potentially cell preserving effect in the retinal ischaemia-reperfusion model. Intravitreal BMSCs may be of potential interest for the therapy of retinal vascular disorders. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley

  1. Retinal Biochemistry, Physiology and Cell Biology.

    PubMed

    Smith, Ricardo Luiz; Sivaprasad, Sobha; Chong, Victor

    2016-01-01

    The vitreous, the vasculature of the retina, macular pigments, phototransduction, retinal pigment epithelium, Bruch's membrane and the extracellular matrix, all play an important role in the normal function of the retina as well as in diseases. Understanding the pathophysiology allows us to target treatment. As ocular angiogenesis, immunity and inflammation are covered elsewhere, those subjects will not be discussed in this chapter. © 2016 S. Karger AG, Basel.

  2. Dog Models for Blinding Inherited Retinal Dystrophies

    PubMed Central

    Komáromy, András M.

    2015-01-01

    Abstract Spontaneous canine models exist for several inherited retinal dystrophies. This review will summarize the models and indicate where they have been used in translational gene therapy trials. The RPE65 gene therapy trials to treat childhood blindness are a good example of how studies in dogs have contributed to therapy development. Outcomes in human clinical trials are compared and contrasted with the result of the preclinical dog trials. PMID:25671556

  3. The Bisretinoids of Retinal Pigment Epithelium

    PubMed Central

    Sparrow, Janet R.; Gregory-Roberts, Emily; Yamamoto, Kazunori; Blonska, Anna; Ghosh, Shanti Kaligotla; Ueda, Keiko; Zhou, Jilin

    2012-01-01

    The retina exhibits an inherent autofluorescence that is imaged ophthalmoscopically as fundus autofluorescence. In clinical settings, fundus autofluorescence examination aids in the diagnosis and follow-up of many retinal disorders. Fundus autofluorescence originates from the complex mixture of bisretinoid fluorophores that are amassed by retinal pigment epithelial (RPE) cells as lipofuscin. Unlike the lipofuscin found in other cell-types, this material does not form as a result of oxidative stress. Rather, the formation is attributable to non-enzymatic reactions of vitamin A aldehyde in photoreceptor cells; transfer to RPE occurs upon phagocytosis of photoreceptor outer segments. These fluorescent pigments accumulate even in healthy photoreceptor cells and are generated as a consequence of the light capturing function of the cells. Nevertheless, the formation of this material is accelerated in some retinal disorders including recessive Stargardt disease and ELOVL-4-related retinal degeneration. As such, these bisretinoid side-products are implicated in the disease processes that threaten vision. In this article, we review our current understanding of the composition of RPE lipofuscin, the structural characteristics of the various bisretinoids, their related spectroscopic features and the biosynthetic pathways by which they form. We will revisit factors known to influence the extent of the accumulation and therapeutic strategies being used to limit bisretinoid formation. Given their origin from vitamin A aldehyde, an isomer of the visual pigment chromophore, it is not surprising that the bisretinoids of retina are light sensitive molecules. Accordingly, we will discuss recent findings that implicate the photodegradation of bisretinoid in the etiology of age-related macular degeneration. PMID:22209824

  4. Investigation of Laser-Induced Retinal Damage.

    DTIC Science & Technology

    1992-04-22

    may t used therapeutically to increase the content of AA in sensitive ocular tissue Supported by AFOSR-91-0208, NEI EY-08213, and Rei~ rr , - "revent...8 x 10 It.,dS magnetic resonance; HPCL . high pressure liquid chrom- erythrocytes/mL. I- atography; RPE, retinal pigmented epithelium. Reaction mixture...1982) The reversibility of the vitamin C redox system: R. Liss, electrochemical reasons and biological aspects. Z. Nat- son and M. M. LaVail) pp. 469

  5. Automated retinal robotic laser system instrumentation

    NASA Astrophysics Data System (ADS)

    Barrett, Steven F.; Wright, Cameron H. G.; Jerath, Maya R.; Lewis, R. Stephen, II; Dillard, Bryan C.; Rylander, Henry G., III; Welch, Ashley J.

    1995-05-01

    Researchers at the University of Texas at Austin's Biomedical Engineering Laser Laboratory investigating the medical applications of lasers have worked toward the development of a retinal robotic laser system. The ultimate goal of this ongoing project is to precisely place and control the depth of laser lesions for the treatment of various retinal diseases such as diabetic retinopathy and retinal tears. Researchers at the USAF Academy's Department of Electrical Engineering have also become involved with this research due to similar interests. Separate low speed prototype subsystems have been developed to control lesion depth using lesion reflectance feedback parameters and lesion placement using retinal vessels as tracking landmarks. Both subsystems have been successfully demonstrated in vivo on pigmented rabbits using an argon continuous wave laser. Work is ongoing to build a prototype system to simultaneously control lesion depth and placement. The instrumentation aspects of the prototype subsystems were presented at SPIE Conference 1877 in January 1993. Since then our efforts have concentrated on combining the lesion depth control subsystem and the lesion placement subsystem into a single prototype capable of simultaneously controlling both parameters. We have designed this combined system CALOSOS for Computer Aided Laser Optics System for Ophthalmic Surgery. An initial CALOSOS prototype design is provided. We have also investigated methods to improve system response time. The use of high speed non-standard frame rate CCD cameras and high speed local bus frame grabbers hosted on personal computers are being investigated. A review of system testing in vivo to date is provided in SPIE Conference proceedings 2374-49 (Novel Applications of Lasers and Pulsed Power, Dual-Use Applications of Lasers: Medical session).

  6. Dog models for blinding inherited retinal dystrophies.

    PubMed

    Petersen-Jones, Simon M; Komáromy, András M

    2015-03-01

    Spontaneous canine models exist for several inherited retinal dystrophies. This review will summarize the models and indicate where they have been used in translational gene therapy trials. The RPE65 gene therapy trials to treat childhood blindness are a good example of how studies in dogs have contributed to therapy development. Outcomes in human clinical trials are compared and contrasted with the result of the preclinical dog trials.

  7. Objective Detection of Retinal Vessel Pulsation

    PubMed Central

    Morgan, William H.; Abdul-Rahman, Anmar; Yu, Dao-Yi; Hazelton, Martin L.; Betz-Stablein, Brigid; Lind, Christopher R. P.

    2015-01-01

    Purpose Retinal venous pulsation detection is a subjective sign, which varies in elevated intracranial pressure, venous obstruction and glaucoma. To date no method can objectively measure and identify pulsating regions. Method Using high resolution video-recordings of the optic disk and retina we measured fluctuating light absorption by haemoglobin during pulsation. Pulsation amplitude was calculated from all regions of the retinal image video-frames in a raster pattern. Segmented retinal images were formed by objectively selecting regions with amplitudes above a range of threshold values. These were compared to two observers manually drawing an outline of the pulsating areas while viewing video-clips in order to generate receiver operator characteristics. Results 216,515 image segments were analysed from 26 eyes in 18 research participants. Using data from each eye, the median area under the receiver operator curve (AU-ROC) was 0.95. With all data analysed together the AU-ROC was 0.89. We defined the ideal threshold amplitude for detection of any pulsating segment being that with maximal sensitivity and specificity. This was 5 units (95% confidence interval 4.3 to 6.0) compared to 12 units before any regions were missed. A multivariate model demonstrated that ideal threshold amplitude increased with increased variation in video-sequence illumination (p = 0.0119), but between the two observers (p = 0.0919) or other variables. Conclusion This technique demonstrates accurate identification of retinal vessel pulsating regions with no areas identified manually being missed with the objective technique. The amplitude values are derived objectively and may be a significant advance upon subjective ophthalmodynamometric threshold techniques. PMID:25643350

  8. Retinal prosthetics, optogenetics, and chemical photoswitches.

    PubMed

    Marc, Robert; Pfeiffer, Rebecca; Jones, Bryan

    2014-10-15

    Three technologies have emerged as therapies to restore light sensing to profoundly blind patients suffering from late-stage retinal degenerations: (1) retinal prosthetics, (2) optogenetics, and (3) chemical photoswitches. Prosthetics are the most mature and the only approach in clinical practice. Prosthetic implants require complex surgical intervention and provide only limited visual resolution but can potentially restore navigational ability to many blind patients. Optogenetics uses viral delivery of type 1 opsin genes from prokaryotes or eukaryote algae to restore light responses in survivor neurons. Targeting and expression remain major problems, but are potentially soluble. Importantly, optogenetics could provide the ultimate in high-resolution vision due to the long persistence of gene expression achieved in animal models. Nevertheless, optogenetics remains challenging to implement in human eyes with large volumes, complex disease progression, and physical barriers to viral penetration. Now, a new generation of photochromic ligands or chemical photoswitches (azobenzene-quaternary ammonium derivatives) can be injected into a degenerated mouse eye and, in minutes to hours, activate light responses in neurons. These photoswitches offer the potential for rapidly and reversibly screening the vision restoration expected in an individual patient. Chemical photoswitch variants that persist in the cell membrane could make them a simple therapy of choice, with resolution and sensitivity equivalent to optogenetics approaches. A major complexity in treating retinal degenerations is retinal remodeling: pathologic network rewiring, molecular reprogramming, and cell death that compromise signaling in the surviving retina. Remodeling forces a choice between upstream and downstream targeting, each engaging different benefits and defects. Prosthetics and optogenetics can be implemented in either mode, but the use of chemical photoswitches is currently limited to downstream

  9. Retinal stem/progenitor cells in the ciliary marginal zone complete retinal regeneration: a study of retinal regeneration in a novel animal model.

    PubMed

    Miyake, Ayumi; Araki, Masasuke

    2014-07-01

    Our research group has extensively studied retinal regeneration in adult Xenopus laevis. However, X. laevis does not represent a suitable model for multigenerational genetics and genomic approaches. Instead, Xenopus tropicalis is considered as the ideal model for these studies, although little is known about retinal regeneration in X. tropicalis. In the present study, we showed that a complete retina regenerates at approximately 30 days after whole retinal removal. The regenerating retina was derived from the stem/progenitor cells in the ciliary marginal zone (CMZ), indicating a novel mode of vertebrate retinal regeneration, which has not been previously reported. In a previous study, we showed that in X. laevis, retinal regeneration occurs primarily through the transdifferentiation of retinal pigmented epithelial (RPE) cells. RPE cells migrate to the retinal vascular membrane and reform a new epithelium, which then differentiates into the retina. In X. tropicalis, RPE cells also migrated to the vascular membrane, but transdifferentiation was not evident. Using two tissue culture models of RPE tissues, it was shown that in X. laevis RPE culture neuronal differentiation and reconstruction of the retinal three-dimensional (3-D) structure were clearly observed, while in X. tropicalis RPE culture neither ßIII tubulin-positive cells nor 3-D retinal structure were seen. These results indicate that the two Xenopus species are excellent models to clarify the cellular and molecular mechanisms of retinal regeneration, as these animals have contrasting modes of regeneration; one mode primarily involves RPE cells and the other mode involves stem/progenitor cells in the CMZ. © 2014 Wiley Periodicals, Inc.

  10. Quantitative analysis of retinal changes in hypertension

    NASA Astrophysics Data System (ADS)

    Giansanti, Roberto; Boemi, Massimo; Fumelli, Paolo; Passerini, Giorgio; Zingaretti, Primo

    1995-05-01

    Arterial hypertension is a high prevalence disease in Western countries and it is associated with increased risk for cardiovascular accidents. Retinal vessel changes are common findings in patients suffering from long-standing hypertensive disease. Morphological evaluations of the fundus oculi represent a fundamental tool for the clinical approach to the patient with hypertension. A qualitative analysis of the retinal lesions is usually performed and this implies severe limitations both in the classification of the different degrees of the pathology and in the follow-up of the disease. A diagnostic system based on a quantitative analysis of the retinal changes could overcome these problems. Our computerized approach was intended for this scope. The paper concentrates on the results and the implications of a computerized approach to the automatic extraction of numerical indexes describing morphological details of the fundus oculi. A previously developed image processing and recognition system, documented elsewhere and briefly described here, was successfully tested in pre-clinical experiments and applied in the evaluation of normal as well as of pathological fundus. The software system was developed to extract indexes such as caliber and path of vessels, local tortuosity of arteries and arterioles, positions and angles of crossings between two vessels. The reliability of the results, justified by their low variability, makes feasible the standardization of quantitative parameters to be used both in the diagnosis and in the prognosis of hypertension, and also allows prospective studies based upon them.

  11. Enhancing retinal images by nonlinear registration

    NASA Astrophysics Data System (ADS)

    Molodij, G.; Ribak, E. N.; Glanc, M.; Chenegros, G.

    2015-05-01

    Being able to image the human retina in high resolution opens a new era in many important fields, such as pharmacological research for retinal diseases, researches in human cognition, nervous system, metabolism and blood stream, to name a few. In this paper, we propose to share the knowledge acquired in the fields of optics and imaging in solar astrophysics in order to improve the retinal imaging in the perspective to perform a medical diagnosis. The main purpose would be to assist health care practitioners by enhancing the spatial resolution of the retinal images and increase the level of confidence of the abnormal feature detection. We apply a nonlinear registration method using local correlation tracking to increase the field of view and follow structure evolutions using correlation techniques borrowed from solar astronomy technique expertise. Another purpose is to define the tracer of movements after analyzing local correlations to follow the proper motions of an image from one moment to another, such as changes in optical flows that would be of high interest in a medical diagnosis.

  12. [Stem cell therapy for retinal diseases].

    PubMed

    Balmer, J; Stanzel, B V; Fischer, M D

    2015-09-01

    Due to an ageing population the incidence and prevalence of retinal diseases and visual disabilities will continue to grow. A great number of patients would principally be able to benefit from a stem cell-based therapy. To introduce readers to the terminology and current concepts associated with stem cell therapy in ocular research and to provide an overview of the current status of preclinical and clinical research. We performed a systematic review of relevant entries on ocular stem cell therapy for retinal diseases in PubMed and ClinicalTrials.gov. Differences between various stem cell types are displayed systematically, followed by a discussion of preclinical studies. Translational aspects are highlighted leading to the first clinical trials, including surgical and ethical facets. In preclinical studies, photoreceptor cell precursors and retinal pigment epithelium (RPE) cells were differentiated and subretinally transplanted into animal models. Besides exclusion of a teratoma formation, some functional improvements were also observed. Intraocular transplantation of stem cell-derived RPE cells was the first successful clinical application of pluripotent stem cells in man. Promising results of preclinical and clinical studies have identified important challenges and confirmed the potential of stem cell therapy for ophthalmology.

  13. Psychosocial Risk Factors and Retinal Microvascular Signs

    PubMed Central

    Jensen, Richard A.; Shea, Steven; Ranjit, Nalini; Diez-Roux, Ana; Wong, Tien Y.; Klein, Ronald; Klein, Barbara E. K.; Cotch, Mary Frances; Siscovick, David S.

    2010-01-01

    The association between psychosocial risk factors and retinal microvascular signs was examined in the Multi-Ethnic Study of Atherosclerosis. Subjects were recruited from Baltimore, Maryland; Chicago, Illinois; Forsyth County, North Carolina; Los Angeles County, California; New York, New York; and St. Paul, Minnesota. Levels of depressive symptoms, trait anger, trait anxiety, chronic burdens, emotional support, and cynical distrust were assessed by questionnaire (from July 2000 to July 2002). Digital retinal images (from August 2002 to January 2004) from 6,147 participants were used to evaluate retinopathy and retinal vascular caliber. After controlling for potential confounding factors, the authors found that subjects without access to emotional support (Enriched Social Support Instrument score of <19 vs. ≥19) had 60% greater odds of retinopathy (odds ratio = 1.6, 95% confidence interval (CI): 1.3, 2.0). Subjects with high Spielberger trait-anxiety scale scores (≥22 vs. ≤14) and subjects with high depressive symptoms (Center for Epidemiology Studies Depression Scale score, ≥16 vs. <16) were also more likely to have retinopathy (odds ratio = 1.4, 95% CI: 1.1, 1.9 and odds ratio = 1.5, 95% CI: 1.2, 1.9), respectively. In this cross-sectional study, lack of emotional support, increased trait anxiety, and more depressive symptoms were associated with retinopathy signs, independently of other known risk factors. PMID:20035010

  14. Finite element modeling of retinal prosthesis mechanics

    NASA Astrophysics Data System (ADS)

    Basinger, B. C.; Rowley, A. P.; Chen, K.; Humayun, M. S.; Weiland, J. D.

    2009-10-01

    Epiretinal prostheses used to treat degenerative retina diseases apply stimulus via an electrode array fixed to the ganglion cell side of the retina. Mechanical pressure applied by these arrays to the retina, both during initial insertion and throughout chronic use, could cause sufficient retinal damage to reduce the device's effectiveness. In order to understand and minimize potential mechanical damage, we have used finite element analysis to model mechanical interactions between an electrode array and the retina in both acute and chronic loading configurations. Modeling indicates that an acute tacking force distributes stress primarily underneath the tack site and heel edge of the array, while more moderate chronic stresses are distributed more evenly underneath the array. Retinal damage in a canine model chronically implanted with a similar array occurred in correlating locations, and model predictions correlate well with benchtop eyewall compression tests. This model provides retinal prosthesis researchers with a tool to optimize the mechanical electrode array design, but the techniques used here represent a unique effort to combine a modifiable device and soft biological tissues in the same model and those techniques could be extended to other devices that come into mechanical contact with soft neural tissues.

  15. Automated quality assessment of retinal fundus photos.

    PubMed

    Paulus, Jan; Meier, Jörg; Bock, Rüdiger; Hornegger, Joachim; Michelson, Georg

    2010-11-01

    Automated, objective and fast measurement of the image quality of single retinal fundus photos to allow a stable and reliable medical evaluation. The proposed technique maps diagnosis-relevant criteria inspired by diagnosis procedures based on the advise of an eye expert to quantitative and objective features related to image quality. Independent from segmentation methods it combines global clustering with local sharpness and texture features for classification. On a test dataset of 301 retinal fundus images we evaluated our method on a given gold standard by human observers and compared it to a state of the art approach. An area under the ROC curve of 95.3% compared to 87.2% outperformed the state of the art approach. A significant p-value of 0.019 emphasizes the statistical difference of both approaches. The combination of local and global image statistics models the defined quality criteria and automatically produces reliable and objective results in determining the image quality of retinal fundus photos.

  16. [Rhegmatogenous retinal detachments. Seasonal variation and incidence].

    PubMed

    Thelen, U; Gerding, H; Clemens, S

    1997-09-01

    Seasonal variations in the relative incidence of rhegmatogenous retinal detachment were reported as a trend in several studies on the database of relatively limited cohort sizes. An analysis on this topic was performed with a long-term database. A total of 3073 files of patients with rhegmatogenous retinal detachment, covering 11 years of observation, were reviewed for this study. Patients with signs of long-standing detachment or other predisposing diseases were excluded, so that a basic study population of 2314 patients remained for the analysis. The averaged seasonal incidence of rhegmatogenous detachments revealed a significant (P < 0.005) mid-summer peak (n in July = 228) and a winter trough (mean of December-January = 161; difference = 36%). Phase and curve fitting of the seasonal variations in the number of retina detachment cases was similar to the seasonal variation of the astronomic duration of the day (P < 0.001). The relation was closer compared to the average duration of light exposure per day calculated from behavioural data and the astronomic length of light phase (P < 0.0002). This long-time study revealed a close correlation of the relative seasonal incidence of retinal detachment and the seasonal variation of light hours per day. So far, this observations cannot be explained pathogenetically. Two basic hypotheses ought to be investigated further: (1) The influence of light on the generation of toxic oxygen radicals and the subsequent destruction of the vitreous and (2) possible light-induced changes in vitreoretinal adhesion.

  17. Rhegmatogenous retinal detachment following intravitreal ocriplasmin.

    PubMed

    Madi, Haifa A; Haynes, Richard J; Depla, Diana; de la Cour, Morten D; Lesnik-Oberstein, Sarit; Muqit, Mahi M K; Patton, Niall; Price, Nick; Steel, David H W

    2016-12-01

    To describe the characteristics and outcomes of patients presenting with rhegmatogenous retinal detachment (RRD) after ocriplasmin (OCP) injection. Retrospective, multi-centre, observational case series with case note review. Eight patients with symptomatic vitreomacular traction (six with concomitant macular hole) were diagnosed with RRD after a median of 16 days (range 3-131 days) post-OCP injection. Presentation was within 3 weeks of the OCP injection in six of the cases. Five patients presented with symptoms post-OCP, and three were diagnosed asymptomatically on planned visits. Seven cases were phakic, one had high myopia (>8 dioptres), and two cases had lattice degeneration. Following RRD surgery, hole closure was achieved in 5/6 MH cases. The final median BCVA at 7 months was 20/80 (range 20/40-20/1200) similar to the baseline BCVA 20/80, with four patients gaining ≥1 line of vision compared to baseline but three losing ≥3 lines. RRD is a non-negligible risk associated with intravitreal OCP, and it should be used with caution in eyes with high myopia and peripheral retinal pathology predisposing to RRD. Detailed peripheral retinal examination is recommended pre- and postoperatively at all visits. Patients should be advised to seek attention if symptoms recur after initial presentation.

  18. [Optogenetics and prosthetic treatment of retinal degeneration].

    PubMed

    Kirpichnikov, M P; Ostrovskiy, M A

    2015-01-01

    This is a review of the current state of optogenetics-based research in the field of ophthalmology and physiology of vision. Optogenetics employs an interdisciplinary approach that amalgamates gene engineering, optics, and physiology. It involves exogenous expression of a light-activated protein in a very particular retinal cell enabling regulation (stimulation vs. inhibition) of its physiological activity. The experience with gene therapy came in very useful for optogenetics. However, unlike gene therapy, which is aimed at repairing damaged genes or replacing them with healthy ones, optogenetics is focused on protein genes delivery for further molecular control of the cell. In retina, the loss of photoreceptors is not necessarily followed by neuronal loss (at least ganglion cells remain intact), which determines the practicability of prosthetic treatment. Clinical trials can now be considered, owing to the first successful conversion of ganglion cells of mouse degenerative retinas into artificial photoreceptive cells with ON and OFF receptive fields, which is crucial for spatial vision. The following issues are reviewed here in detail: 1. Choice of cell targets within the degenerative retina. 2. Strategy of utilizing the existing light-sensitive agents and development of new optogenetic tools. 3. Gene delivery and expression in retinal cells. 4. Methods of evaluating the treatment success. 5. Selection criteria for optogenetic prosthetics. The conclusion discusses currently unsolved problems and prospects for optogenetic approaches to retinal prosthetics.

  19. Aldose reductase mediates retinal microglia activation

    SciTech Connect

    Chang, Kun-Che; Shieh, Biehuoy; Petrash, J. Mark, E-mail: mark.petrash@ucdenver.edu

    2016-04-29

    Retinal microglia (RMG) are one of the major immune cells in charge of surveillance of inflammatory responses in the eye. In the absence of an inflammatory stimulus, RMG reside predominately in the ganglion layer and inner or outer plexiform layers. However, under stress RMG become activated and migrate into the inner nuclear layer (INL) or outer nuclear layer (ONL). Activated RMG in cell culture secrete pro-inflammatory cytokines in a manner sensitive to downregulation by aldose reductase inhibitors. In this study, we utilized CX3CR1{sup GFP} mice carrying AR mutant alleles to evaluate the role of AR on RMG activation and migrationmore » in vivo. When tested on an AR{sup WT} background, IP injection of LPS induced RMG activation and migration into the INL and ONL. However, this phenomenon was largely prevented by AR inhibitors or in AR null mice, or was exacerbated in transgenic mice that over-express AR. LPS-induced increases in ocular levels of TNF-α and CX3CL-1 in WT mice were substantially lower in AR null mice or were reduced by AR inhibitor treatment. These studies demonstrate that AR expression in RMG may contribute to the proinflammatory phenotypes common to various eye diseases such as uveitis and diabetic retinopathy. - Highlights: • AR inhibition prevents retinal microglial activation. • Endotoxin-induced ocular cytokine production is reduced in AR null mice. • Overexpression of AR spontaneously induces retinal microglial activation.« less

  20. Management of Giant Retinal Tear Detachments.

    PubMed

    Berrocal, Maria H; Chenworth, Megan L; Acaba, Luis A

    2017-01-01

    Giant retinal tears (GRTs) are full-thickness circumferential tears of more than 90 degrees of the retina that are associated with vitreous detachment. They are related to ocular trauma, high myopia, aphakia, pseudophakia, genetic mutations involving collagen and young age. GRTs comprise 1.5% of all rhegmatogenous retinal detachments and the average age of incidence is 42 years. GRTs are more common in males, as 72% of all cases occur in males. The incidence of GRTs in the general population is estimated to be 0.05 per 100,000 individuals. Common techniques used in the management of GRTs include fluid-air exchange, pneumatic retinopexy, scleral buckling, primary vitrectomy with gas or silicone oil tamponade, and combined scleral buckle-vitrectomies. However, management of GRTs poses a great challenge to physicians due to the high risk of intra- and post-operative complications and the many technical difficulties involved. The advent of perfluorocarbon liquids (PFCL) and the use of micro-incisional surgery for the treatment of GRTs has provided new opportunities for the management of GTRs. Today, retinal reattachment can be achieved in 94-100% of cases.

  1. Gene replacement therapy for retinal CNG channelopathies.

    PubMed

    Schön, Christian; Biel, Martin; Michalakis, Stylianos

    2013-10-01

    Visual phototransduction relies on the function of cyclic nucleotide-gated channels in the rod and cone photoreceptor outer segment plasma membranes. The role of these ion channels is to translate light-triggered changes in the second messenger cyclic guanosine 3'-5'-monophosphate levels into an electrical signal that is further processed within the retinal network and then sent to higher visual centers. Rod and cone photoreceptors express distinct CNG channels. The rod photoreceptor CNG channel is composed of one CNGB1 and three CNGA1 subunits, whereas the cone channel is formed by one CNGB3 and three CNGA3 subunits. Mutations in any of these channel subunits result in severe and currently untreatable retinal degenerative diseases like retinitis pigmentosa or achromatopsia. In this review, we provide an overview of the human diseases and relevant animal models of CNG channelopathies. Furthermore, we summarize recent results from preclinical gene therapy studies using adeno-associated viral vectors and discuss the efficacy and translational potential of these gene therapeutic approaches.

  2. [Visual rehabilitation in patients with retinitis pigmentosa].

    PubMed

    de Castro, Celina Tamaki Monteiro; Berezovsky, Adriana; de Castro, Danilo Dimas Monteiro; Salomão, Solange Rios

    2006-01-01

    To determine which low-vision aids could be useful to patients with retinitis pigmentosa and also the benefits that the rehabilitation program could provide based on visual acuity and/or daily visual tasks. A group of 30 patients with retinitis pigmentosa aged from 7 to 73 years were enrolled in this study. Visual acuity and visual function tests (visual field, full-field electroretinogram) was performed and low-vision aids tested. Information about the use of the remaining vision was obtained. After choosing the best optical or electronic devices and before their prescription, a low-vision training program was carried out. The best corrected visual acuity varied from HM (hand movements) to 20/40 for distance and visual acuity better than 16M to 0.5M for near. 90% of the patients had optical devices prescribed: 13 for near, 9 for distance, 2 electronic devices and 3 filters. Three patients with extremely narrow visual field and very low visual acuity were referred to orientation and mobility. The low-vision aids were useful for the retinitis pigmentosa patients: telescopes, hand-held magnifiers, stand magnifiers, half-eye base-in prism lenses, electronic devices and illumination control were beneficial to enhance visual acuity and visual efficiency. The prescription of low-vision aids was helpful in daily-life activities and a high level of satisfaction with the implemented visual rehabilitation program was reported.

  3. Optimal retinal cyst segmentation from OCT images

    NASA Astrophysics Data System (ADS)

    Oguz, Ipek; Zhang, Li; Abramoff, Michael D.; Sonka, Milan

    2016-03-01

    Accurate and reproducible segmentation of cysts and fluid-filled regions from retinal OCT images is an important step allowing quantification of the disease status, longitudinal disease progression, and response to therapy in wet-pathology retinal diseases. However, segmentation of fluid-filled regions from OCT images is a challenging task due to their inhomogeneous appearance, the unpredictability of their number, size and location, as well as the intensity profile similarity between such regions and certain healthy tissue types. While machine learning techniques can be beneficial for this task, they require large training datasets and are often over-fitted to the appearance models of specific scanner vendors. We propose a knowledge-based approach that leverages a carefully designed cost function and graph-based segmentation techniques to provide a vendor-independent solution to this problem. We illustrate the results of this approach on two publicly available datasets with a variety of scanner vendors and retinal disease status. Compared to a previous machine-learning based approach, the volume similarity error was dramatically reduced from 81:3+/-56:4% to 22:2+/-21:3% (paired t-test, p << 0:001).

  4. Two Japanese cases of battered child syndrome with retinal hemorrhage.

    PubMed

    Hosokawa, T; Hayasaka, S; Yabata, K; Tateda, H

    1986-01-01

    We present 2 cases of battered child syndrome with retinal hemorrhage. Case 1 is a 6-year-old boy who was blinded in both eyes following abuse by his mother's common-law husband. Retinal hemorrhages and optic atrophy were found in both eyes. Case 2 is a 6-month-old boy who developed dyspnea following episodes of abuse by his mother's common-law husband. Retinal hemorrhages were visible in both fundi. We believe that retinal hemorrhage is the most frequent clinical finding in abused children and its presence should alert the ophthalmologist to suspect battered child syndrome.

  5. The influence of retinal eye diseases on painting.

    PubMed

    Ivanišević, Petar; Ivanišević, Milan

    2015-03-01

    In this work the possible influences of some retinal eye problems on paintings of several famous artists are considered. The change of painting styles and artistic expression in different periods and ages in a group of world-wide well-known painters are described and correlated with known or suspected retinal diseases. Some of them largely became recognizable because of that. Contemplations are offered about the effects of retinal diseases in the works of Degas, Munch, Cézanne, O'Keeffe, Constable and Goya. Retinal eye diseases have a significant impact on the work of selected famous painters.

  6. Genetic determinants of hyaloid and retinal vasculature in zebrafish

    PubMed Central

    Alvarez, Yolanda; Cederlund, Maria L; Cottell, David C; Bill, Brent R; Ekker, Stephen C; Torres-Vazquez, Jesus; Weinstein, Brant M; Hyde, David R; Vihtelic, Thomas S; Kennedy, Breandan N

    2007-01-01

    Background The retinal vasculature is a capillary network of blood vessels that nourishes the inner retina of most mammals. Developmental abnormalities or microvascular complications in the retinal vasculature result in severe human eye diseases that lead to blindness. To exploit the advantages of zebrafish for genetic, developmental and pharmacological studies of retinal vasculature, we characterised the intraocular vasculature in zebrafish. Results We show a detailed morphological and developmental analysis of the retinal blood supply in zebrafish. Similar to the transient hyaloid vasculature in mammalian embryos, vessels are first found attached to the zebrafish lens at 2.5 days post fertilisation. These vessels progressively lose contact with the lens and by 30 days post fertilisation adhere to the inner limiting membrane of the juvenile retina. Ultrastructure analysis shows these vessels to exhibit distinctive hallmarks of mammalian retinal vasculature. For example, smooth muscle actin-expressing pericytes are ensheathed by the basal lamina of the blood vessel, and vesicle vacuolar organelles (VVO), subcellular mediators of vessel-retinal nourishment, are present. Finally, we identify 9 genes with cell membrane, extracellular matrix and unknown identity that are necessary for zebrafish hyaloid and retinal vasculature development. Conclusion Zebrafish have a retinal blood supply with a characteristic developmental and adult morphology. Abnormalities of these intraocular vessels are easily observed, enabling application of genetic and chemical approaches in zebrafish to identify molecular regulators of hyaloid and retinal vasculature in development and disease. PMID:17937808

  7. Stem cells in retinal regeneration: past, present and future

    PubMed Central

    Ramsden, Conor M.; Powner, Michael B.; Carr, Amanda-Jayne F.; Smart, Matthew J. K.; da Cruz, Lyndon; Coffey, Peter J.

    2013-01-01

    Stem cell therapy for retinal disease is under way, and several clinical trials are currently recruiting. These trials use human embryonic, foetal and umbilical cord tissue-derived stem cells and bone marrow-derived stem cells to treat visual disorders such as age-related macular degeneration, Stargardt's disease and retinitis pigmentosa. Over a decade of analysing the developmental cues involved in retinal generation and stem cell biology, coupled with extensive surgical research, have yielded differing cellular approaches to tackle these retinopathies. Here, we review these various stem cell-based approaches for treating retinal diseases and discuss future directions and challenges for the field. PMID:23715550

  8. Characteristics of rhegmatogenous retinal detachment after refractive surgery: comparison with myopic eyes with retinal detachment.

    PubMed

    Kang, Hae Min; Lee, Christopher Seungkyu; Park, Hyun Joo; Lee, Kyu Ho; Byeon, Suk Ho; Koh, Hyoung Jun; Lee, Sung Chul

    2014-03-01

    To evaluate the characteristics of rhegmatogenous retinal detachment (RD) in patients with previous laser in situ keratomileusis (LASIK) and compare them to RD in patients with previous laser assisted subepithelial keratomileusis (LASEK) and myopic patients with no previous refractive surgery. Retrospective, comparative case series. In 106 eyes of 106 patients with RD, patients with previous refractive surgery included 21 eyes after LASIK and 13 eyes after LASEK; 72 myopic patients with refractive errors of -3.0 diopters or less were grouped as the R (-) group. Characteristics of RD included distribution of RD and associated retinal breaks, location and number of retinal breaks, presence of lattice degeneration, and axial lengths. The mean interval between refractive surgery and the onset of rhegmatogenous RD was 63.7 ± 43.5 months, occurring across a broad spectrum of time intervals. There were no significant differences among the LASIK group, the LASEK group, and the R (-) group in axial length (26.8 mm vs 26.4 mm vs 26.9 mm, respectively); in mean number of retinal holes/tears, (2.1/1.5, 0.9/1.4, 1.5/1.6, respectively); or in the presence of lattice degeneration (52.4% vs 46.2% vs 43.1%, respectively). Distribution of RD and associated retinal breaks were also not significantly different; retinal holes and tears were more prevalent in the temporal quadrants, and inferotemporal quadrants were the most commonly detached areas in both the LASEK and LASIK groups and in the R (-) group. Myopia is a well-known risk factor for rhegmatogenous RD and may contribute more to the development of RD in myopic patients after refractive surgery, rather than refractive surgery itself. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Retinal and choroidal vascular features in patients with retinitis pigmentosa imaged by OCT based microangiography.

    PubMed

    Rezaei, Kasra A; Zhang, Qinqin; Chen, Chieh-Li; Chao, Jennifer; Wang, Ruikang K

    2017-07-01

    To image vascular features of retinitis pigmentosa (RP) using optical coherence tomography angiography (OCTA). Patients with RP were imaged by spectral domain optical coherence tomography based angiography (OCTA). The optical microangiography (OMAG) algorithm was applied to scanned datasets to generate 3D OCTA retinal angiograms, i.e., OMAG angiograms. Motion tracking was used to minimize artifacts due to eye movement, and large field of view OMAG angiograms were achieved through a montage scanning protocol. For better visualization, depth volumes were segmented to separate the superficial retinal layers from deep outer retinal layers. The choriocapillaris and other choroidal layers were also segmented. To investigate the changes in retinal architecture, the inner segment/outer segment (IS/OS) junction to RPE layer was segmented to generate en face structural images through averaging intensity projection. Color fundus images and/or Goldmann visual fields were available for comparison of the findings to OMAG images. A total of 25 eyes (13 patients, seven women and six men) diagnosed with RP at various stages were enrolled in this study from October 2014 to January 2016 and imaged by OCTA. The resulting OMAG angiograms provided detailed visualization of retinal and choroidal vascular networks presented within the retina and choroid in a large field of view (FOV) (∼6.7 mm × 6.7 mm). All patients with a severity score greater than 3 showed abnormal microvasculature in both deep retinal and choroidal layers on OMAG images. Images of patients with a score of 4 indicating only peripheral abnormalities demonstrated relatively normal vasculature networks. Microvascular changes in the retinal and choroidal vasculature correlate with structural changes in the slab from IS/OS junction to RPE layer. OCTA is useful in evaluating the microvascular changes in a large FOV encompassing the maculae of patients with RP. The large FOV of OMAG angiograms, enabled by the motion

  10. Surgical management of retinal diseases: proliferative diabetic retinopathy and traction retinal detachment.

    PubMed

    Cruz-Iñigo, Yousef J; Acabá, Luis A; Berrocal, Maria H

    2014-01-01

    Current indications for pars plana vitrectomy in patients with proliferative diabetic retinopathy (PDR) include vitreous hemorrhage, tractional retinal detachment (TRD), combined tractional and rhegmatogenous retinal detachment (CTRRD), diabetic macular edema associated with posterior hyaloidal traction, and anterior segment neovascularization with media opacities. This chapter will review the indications, surgical objectives, adjunctive pharmacotherapy, microincision surgical techniques, and outcomes of diabetic vitrectomy for PDR, TRD, and CTRRD. With the availability of new microincision vitrectomy technology, wide-angle microscope viewing systems, and pharmacologic agents, vitrectomy can improve visual acuity and achieve long-term anatomic stability in eyes with severe complications from PDR. © 2014 S. Karger AG, Basel

  11. Retinal Waves Modulate an Intraretinal Circuit of Intrinsically Photosensitive Retinal Ganglion Cells

    PubMed Central

    Arroyo, David A.; Kirkby, Lowry A.

    2016-01-01

    Before the maturation of rod and cone photoreceptors, the developing retina relies on light detection by intrinsically photosensitive retinal ganglion cells (ipRGCs) to drive early light-dependent behaviors. ipRGCs are output neurons of the retina; however, they also form functional microcircuits within the retina itself. Whether ipRGC microcircuits exist during development and whether they influence early light detection remain unknown. Here, we investigate the neural circuit that underlies the ipRGC-driven light response in developing mice. We use a combination of calcium imaging, tracer coupling, and electrophysiology experiments to show that ipRGCs form extensive gap junction networks that strongly contribute to the overall light response of the developing retina. Interestingly, we found that gap junction coupling was modulated by spontaneous retinal waves, such that acute blockade of waves dramatically increased the extent of coupling and hence increased the number of light-responsive neurons. Moreover, using an optical sensor, we found that this wave-dependent modulation of coupling is driven by dopamine that is phasically released by retinal waves. Our results demonstrate that ipRGCs form gap junction microcircuits during development that are modulated by retinal waves; these circuits determine the extent of the light response and thus potentially impact the processing of early visual information and light-dependent developmental functions. SIGNIFICANCE STATEMENT Light-dependent functions in early development are mediated by intrinsically photosensitive retinal ganglion cells (ipRGCs). Here we show that ipRGCs form an extensive gap junction network with other retinal neurons, including other ipRGCs, which shapes the retina's overall light response. Blocking cholinergic retinal waves, which are the primary source of neural activity before maturation of photoreceptors, increased the extent of ipRGC gap junction networks, thus increasing the number of light

  12. Higher retinal vessel oxygen saturation: investigating its relationship with macular oedema in retinitis pigmentosa patients.

    PubMed

    Bojinova, Rossiana I; Schorderet, Daniel F; Valmaggia, Christophe; Türksever, Cengiz; Schoetzau, Andreas; Todorova, Margarita G

    2018-03-06

    Primary objective-to investigate the effect of retinal vessel oxygen saturation (SO 2 ) on macular oedema (ME) in retinitis pigmentosa (RP) patients. Secondary objective-to link the presence of ME to metabolic (oxygen saturation of retinal vessels, SO 2 ), functional (multifocal electroretinography, mfERG) and structural (Spectral Domain Optical Coherent Tomography, SD-OCT) alterations in RP. Prospective, cross-sectional, non-interventional study. Patients with typical RP (N = 37) and controls (N = 19), who underwent retinal vessel Oximetry (RO), SD-OCT and mfERG, were included. A computer-based program of the retinal vessel analyser unit (IMEDOS Systems UG, Jena, Germany) was used to measure SO 2 . We evaluated the mean SO 2 , in all major retinal arterioles (oxygen saturation in retinal arterioles, A-SO 2 , %) and venules (oxygen saturation in retinal venules, V-SO 2 , %). MfERG responses were averaged in zones (zone 1 (0-3°), zone 2 (3-8°) and zone 3 (8-15°)) and compared to corresponding areas of the OCT. The effect of ME on SO 2 was evaluated dividing the RP in two subgroups: with clinical appearance of ME (ME-RP) and without it (no-ME-RP). Parallel recording and juxtaposition of metabolic (SO 2 ) to structural (OCT) and functional-(mfERG) measures. Mean ( ± SD) A-SO 2 and V-SO 2 were higher in no-ME-RP (96.77% (±6.31) and 59.93% (±7.76)) and even higher in the ME-RP (99.82% (±6.21) and 65.63% (±7.63)), compared to controls (93.15% (±3.76) and 53.77% (±3.70), p ≤ 0.006). The subgroup ME-RP differed significantly from the subgroup no-ME-RP by increased A-SO 2 and V-SO 2 , p ≤ 0.026. The presence of ME confirmed a different relationship between the altered SO 2 and the vessel diameters, against the functional and structural parameters. Based on our results, the presence of macular oedema indicates a tendency toward greater alteration of the metabolic function in RP patients.

  13. Photovoltaic retinal prosthesis: implant fabrication and performance

    PubMed Central

    Wang, Lele; Mathieson, K; Kamins, T I; Loudin, J D; Galambos, L; Goetz, G; Sher, A; Mandel, Y; Huie, P; Lavinsky, D; Harris, J S; Palanker, D V

    2012-01-01

    Objective To develop and test a photovoltaic retinal prosthesis for restoring sight to patients blinded by degenerative retinal diseases. Approach A silicon photodiode array for subretinal stimulation has been fabricated by a silicon-integrated-circuit/MEMS process. Each pixel in the two-dimensional array contains three series-connected photodiodes, which photovoltaically convert pulsed near-infrared light into bi-phasic current to stimulate nearby retinal neurons without wired power connections. The device thickness is chosen to be 30 μm to absorb a significant portion of light while still being thin enough for subretinal implantation. Active and return electrodes confine current near each pixel and are sputter coated with iridium oxide to enhance charge injection levels and provide a stable neural interface. Pixels are separated by 5 μm-wide trenches to electrically isolate them and to allow nutrient diffusion through the device. Three sizes of pixels (280μm, 140 μm, and 70 μm) with active electrodes of 80 μm, 40 μm and 20 μm in diameter were fabricated. Main results The turn-on voltages of one-, two- and three-series-connected photodiode structures are approximately 0.6V, 1.2V and 1.8V, respectively. The measured photo-responsivity per diode at 880 nm wavelength is ~0.36 A/W, at zero voltage bias and scales with the exposed silicon area. For all three pixel sizes, the reverse-bias dark current is sufficiently low (<100 pA) for our application. Pixels of all three sizes reliably elicit retinal responses at safe near-infrared light irradiances, with good acceptance of the photodiode array in the subretinal space. Significance The fabricated device delivers efficient retinal stimulation at safe near-infrared light irradiances without any wired power connections, which greatly simplifies the implantation procedure. Presence of the return electrodes in each pixel helps to localize the current, and thereby improves resolution. PMID:22791690

  14. Rhegmatogenous retinal detachment and conventional surgical treatment.

    PubMed

    Golubovic, M

    2013-01-01

    The aim of the paper was to present the efficacy and indications for application of conventional surgical treatment of retinal detachment by using external implants, that is,application of encircling band and buckle. This study comprised patients from the University Eye Clinic in Skopje. A total of 33 patients were diagnosed and surgically treated in the period between May 2010 and August 2011. Conventional surgery was applied in smaller number of patients whose changes of the vitreous body were manifested by detachment of posterior hyaloid membrane, syneresis, with appearance of a small number of pigment cells in the vitreous body and synchysis, and the very retina was with fresh detachment without folds or epiretinal changes (that is, PVR A grade). There were a larger number of patients with more distinct proliferative changes of the vitreous body and of the retina, grades PVR B to C1-C2, and who also underwent the same surgical approach. Routine ophthalmologic examinations were performed, including: determination of visual acuity by Snellen's optotypes, determination of eye pressure with Schiotz's tonometer, examination of anterior segment on biomicroscopy, indirect biomicroscopy of posterior eye segment (vitreous body and retina) and examination on biomicroscopy with Goldmann prism, B scan echography of the eyes before and after surgical treatment. Conventional treatment was used by external application of buckle or application of buckle and encircling band. In case of one break, radial buckle was applied and in case of multiple breaks in one quadrant limbus parallel buckle was applied. Besides buckle, encircling band was applied in patients with total or subtotal retinal detachment with already present distinct changes in the vitreous body (PVR B or C1-C2) and degenerative changes in the vitreous body. Breaks were closed with cryopexy. The results obtained have shown that male gender was predominant and that the disease was manifested in younger male adults

  15. A method for volumetric retinal tissue oxygen tension imaging.

    PubMed

    Felder, Anthony E; Wanek, Justin; Teng, Pang-Yu; Blair, Norman P; Shahidi, Mahnaz

    2018-01-01

    Inadequate retinal oxygenation occurs in many vision-threatening retinal diseases, including diabetic retinopathy, retinal vascular occlusions, and age-related macular degeneration. Therefore, techniques that assess retinal oxygenation are necessary to understand retinal physiology in health and disease. The purpose of the current study is to report a method for the three-dimensional (3D) imaging of retinal tissue oxygen tension (tPO 2 ) in rats. Imaging was performed in Long Evans pigmented rats under systemic normoxia (N = 6) or hypoxia (N = 3). A vertical laser line was horizontally scanned on the retina and a series of optical section phase-delayed phosphorescence images were acquired. From these images, phosphorescence volumes at each phase delay were constructed and a 3D retinal tPO 2 volume was generated. Retinal tPO 2 volumes were quantitatively analyzed by generating retinal depth profiles of mean tPO 2 (M tPO2 ) and the spatial variation of tPO 2 (SV tPO2 ). The effects of systemic condition (normoxia/hypoxia) and retinal depth on M tPO2 and SV tPO2 were determined by mixed linear model. Each 3D retinal tPO 2 volume was approximately 500 × 750 × 200 μm (horizontal × vertical × depth) and consisted of 45 en face tPO 2 images through the retinal depth. M tPO2 at the chorioretinal interface was significantly correlated with systemic arterial oxygen tension (P = 0.007; N = 9). There were significant effects of both systemic condition and retinal depth on M tPO2 and SV tPO2 , such that both were lower under hypoxia than normoxia and higher in the outer retina than inner retina (P < 0.001). For the first time, 3D imaging of retinal tPO 2 was demonstrated, with potential future application for assessment of physiological alterations in animal models of retinal diseases.

  16. Pathogenesis of rhegmatogenous retinal detachment: predisposing anatomy and cell biology.

    PubMed

    Mitry, Danny; Fleck, Brian W; Wright, Alan F; Campbell, Harry; Charteris, David G

    2010-01-01

    The pathogenesis of rhegmatogenous retinal detachment is complex, and our knowledge of the exact mechanism of vitreoretinal attachment and detachment remains incomplete. We performed a Medline, Ovid, and EMBASE search using search words rhegmatogenous, retinal detachment, vitreous, and retinal adhesion. All appropriate articles were reviewed, and the evidence was compiled. Cortical vitreous contains fibrillar collagens type II, V/XI, and IX. The inner limiting membrane of the retina contains collagens type I, IV, VI, and XVIII as well as numerous other glycoproteins and potential adhesion molecules. The distribution and age-related changes in the structure of these molecules play an important role in the formation of a retinal break, which may compromise and disrupt the normal mechanisms of neurosensory retinal adhesion. Rhegmatogenous retinal detachment development is intimately related to changes in the fibrillar structure of the aging vitreous culminating in posterior vitreous detachment with regions of persistent and tangential vitreoretinal traction predisposing to retinal tear formation. A complex interplay of factors such as weakening of vitreoretinal adhesion, posterior migration of the vitreous base, and molecular changes at the vitreoretinal interface are important in predisposing to focal areas of vitreoretinal traction precipitating rhegmatogenous retinal detachment. Once formed, the passage of liquefied vitreous through a retinal break may overwhelm normal neurosensory-retinal pigment epithelium adhesion perpetuating and extending detachment and causing visual loss. To understand the molecular events underlying rhegmatogenous retinal detachment so that new therapies can be developed, it is important to appreciate the structural organization of the vitreous, the biology underlying vitreous liquefaction and posterior vitreous detachment, and the mechanisms of vitreoretinal attachment and detachment.

  17. RETINAL DISEASES IN A TERTIARY HOSPITAL IN SOUTHERN NIGERIA.

    PubMed

    Uhumwangho, O M; Itina, E I

    2015-01-01

    Retinal diseases are an important and common cause of ophthalmic consultation. To determine the pattern of retinal diseases in the ophthalmic department of a tertiary hospital in Southern Nigeria. A retrospective review of the case folders of patients with retinal pathologies seen between 2012 and 2013 was performed. Relevant demographic and clinical data was recorded. Analysis was performed for frequencies, proportions and percentages with the GraphPad Instat Software, Inc. version V2.05a program, San Diego, CA. There were 185 patients made of 94 (50.8%) males and 91 (49.2%) females with a peak age group of 61-70 years, (range 1-85 years) who made consultations for retinal diseases. Age related macular degeneration, 37(15.0%), and macula hole, 10(4.0%), were the common macula pathologies while retinal detachment, 11(4.5%), was the most common condition that required emergency vitreo-retinal surgical intervention. Diabetic retinopathy/maculopathy, 31(12.6%), hypertensive retinopathy 22(8.9%), and retinal vascular occlusion 12(4.8%), were the common retinal vascular diseases found. Bilateral visual impairment (low vision and blindness) from retinal diseases was present in 28(14.4%) persons. The common vitreo-retinal treatment options were use of intravitreal antivascular endothelial growth factors 32(13.0%), laser 16(6.5%), and vitreoretinal surgery in 22(8.9%) eyes. Retinal diseases remain an important cause of ophthalmic consultation and visual loss. Provision of facilities to manage these conditions will improve service delivery and quality of lives of affected patients.

  18. All-trans-retinal dimer formation alleviates the cytotoxicity of all-trans-retinal in human retinal pigment epithelial cells.

    PubMed

    Li, Jie; Zhang, Yanli; Cai, Xianhui; Xia, Qingqing; Chen, Jingmeng; Liao, Yi; Liu, Zuguo; Wu, Yalin

    2016-09-14

    Effective clearance of all-trans-retinal (atRAL) from retinal pigment epithelial (RPE) cells is important for avoiding its cytotoxicity. However, the metabolism of atRAL in RPE cells is poorly clarified. The present study was designed to analyze metabolic products of atRAL and to compare the cytotoxicity of atRAL versus its derivative all-trans-retinal dimer (atRAL-dimer) in human RPE cells. We found that all-trans-retinol (atROL) and a mixture of atRAL condensation metabolites including atRAL-dimer and A2E were generated after incubating RPE cells with atRAL for 6h, and the amount of atRAL-dimer was significantly higher than that of A2E. In the eyes of Rdh8 -/- Abca4 -/- mice, a mouse model with defects in retinoid cycle that displays some symbolic characteristics of age-related macular degeneration (AMD), the level of atRAL-dimer was increased compared to wild-type mice, and was even much greater than that of A2E & isomers. The cytotoxicity of atRAL-dimer was reduced compared with its precursor atRAL. The latter could provoke intracellular reactive oxygen species (ROS) overproduction, increase the mRNA expression of several oxidative stress related genes (Nrf2, HO-1, and γ-GCSh), and induce ΔΨm loss in RPE cells. By contrast, the abilities of atRAL-dimer to induce intracellular ROS and oxidative stress were much weaker versus that of concentration-matched atRAL, and atRAL-dimer exhibited no toxic effect on mitochondrial function at higher concentrations. In conclusion, the formation of atRAL-dimer during atRAL metabolic process ameliorates the cytotoxicity of atRAL by reducing oxidative stress. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  19. Changes in Retinal Function and Cellular Remodeling Following Experimental Retinal Detachment in a Rabbit Model

    PubMed Central

    Ofri, Ron; Sandalon, Shai; Weinberger, Dov; Livnat, Tami

    2017-01-01

    Purpose. To explore functional electroretinographic (ERG) changes and associated cellular remodeling following experimental retinal detachment in a rabbit model. Methods. Retinal detachment was created in ten rabbits by injecting 0.1 ml balanced salt solution under the retina. Fundus imaging was performed 0, 3, 7, 14, and 21 days postoperatively. ERGs were recorded pre- and 7 and 21 days postoperatively. Eyes were harvested on day 21 and evaluated immunohistochemically (IHC) for remodeling of second- and third-order neurons. Results. Retinal reattachment occurred within two weeks following surgery. No attenuation was observed in the photopic or scotopic a- and b-waves. A secondary wavefront on the descending slope of the scotopic b-wave was the only ERG result that was attenuated in detached retinas. IHC demonstrated anatomical changes in both ON and OFF bipolar cells. Bassoon staining was observed in the remodeled dendrites. Amacrine and horizontal cells did not alter, but Muller cells were clearly reactive with marked extension. Conclusion. Retinal detachment and reattachment were associated with functional and anatomical changes. Exploring the significance of the secondary scotopic wavefront and its association with the remodeling of 2nd- and 3rd-order neurons will shade more light on functional changes and recovery of the retina. PMID:28491466

  20. The fellow eye in retinal detachment: findings from the Scottish Retinal Detachment Study.

    PubMed

    Mitry, D; Singh, J; Yorston, D; Siddiqui, M A Rehman; Murphy, A L; Wright, A F; Fleck, B W; Campbell, H; Charteris, D G

    2012-01-01

    To characterise the predisposing pathology and clinical features in the fellow eyes of patients recruited as part of the Scottish Retinal Detachment Study. The Scottish Retinal Detachment Study was a 2-year prospectively recruited population-based epidemiology study that sought to recruit all incident cases of primary rhegmatogenous retinal detachment (RRD) in Scotland. A total of 1202 incident cases of primary RRD were recruited in Scotland, over a 2-year period and in 94% (1130 cases) detailed data on the clinical features of fellow eyes with RRD were available. Full-thickness retinal breaks were found in 8.4% (95/1130) of fellow eyes on presentation. Lattice degeneration was present in 14.5% (164/1130) of fellow eyes. Thirteen per cent (148/1130) of affected fellow eyes had a best corrected visual acuity of 6/18 or worse with previous RRD, the second most common cause of poor vision. Overall, 7.3% (88/1202) of cases had RRD in both eyes; 60% of cases with consecutive bilateral RRD presented before the macula were affected. Rhegmatogenous pathology in the fellow eye represents an important threat to vision. Fellow-eye detachments are more common in pseudophakic individuals and those with a more myopic refractive error. Fellow-eye RRD has a greater likelihood of prompt presentation.

  1. Duration of spiral aftereffect as a function of retinal size, retinal place, and hemiretinal transfer.

    DOT National Transportation Integrated Search

    1964-01-01

    This experiment has shown that, although both rods and cones mediate the spiral aftereffect, cone areas give a larger response. Increasing size of the retinal image results in longer durations of SAE but rods are more affected by this increase than a...

  2. Surgery for retinal detachment in patients with giant retinal tear: etiologies, management strategies, and outcomes.

    PubMed

    Gonzalez, Marco A; Flynn, Harry W; Smiddy, William E; Albini, Thomas A; Tenzel, Paul

    2013-01-01

    To evaluate etiologies, management, and outcomes for patients with giant retinal tears undergoing initial surgery at a single institution. Noncomparative, retrospective, consecutive case series at a university referral center including 79 eyes of 77 patients. Blunt trauma constituted 22% of cases. All patients underwent pars plana vitrectomy with gas or silicone oil tamponade. Eighty-five percent (67 eyes) underwent an encircling scleral buckle. Perfluorocarbon liquids were used in 71% (61 eyes). Eighteen percent (14 eyes) underwent re-operation for recurrent retinal detachment. Ninety-two percent (73 eyes) achieved anatomic success with one or more surgical procedures. Visual acuity at last follow-up was at least 20/400 in 84.9% of patients (28 of 33) with 3 clock hours compared to 65.2% (30 of 46) with tears greater than 3 clock hours. Patients with giant retinal tear undergoing surgery achieved high rates of anatomic success, but re-operations were frequent. Better visual outcomes were associated with smaller circumferential dimensions in the giant retinal tears. Copyright 2013, SLACK Incorporated.

  3. Retinal penetration of calpain inhibitors in rats after oral administration.

    PubMed

    Shirasaki, Yoshihisa; Yamaguchi, Masazumi; Miyashita, Hiroyuki

    2006-12-01

    Calpain-mediated proteolysis has been involved in neuronal cell death of retinal neurological degeneration. An aldehyde-based calpain inhibitor, SJA6017 (1), was effective following oral administration in a rat retinal ischemia model but had low oral bioavailability. The aim of this study was to identify calpain inhibitors with good retinal penetration after oral dosing. The orally bioavailable inhibitors, hemiacetal 3 (SNJ-1715), amphipathic ketoamide 5 (SNJ-1945), and pyridine ketoamide 6 (SNJ-2008), were evaluated for their retinal pharmacokinetic (PK) profiles. The retinal drug exposure of these inhibitors was more than tenfold higher than 1. Among these compounds, 5 exhibited the most favorable retinal PK properties, such as good penetration and long half-life. Comparisons of 5 and the structurally related ketoamide 6 suggested that the presence of a methoxy diethylene glycol moiety resulted in the inhibitor with high penetration into the retina and the sustained high retinal levels. Ketoamide 5 was selected as the development candidate for the treatment of retinal diseases.

  4. Vitrectomy of rhegmatogenous retinal detachment in morning glory syndrome.

    PubMed

    Yang, Xiao-Li; Zhang, Xi

    2010-01-01

    We report a case of retinal detachment in morning glory syndrome(MGS). We think that identification of the retinal break, removal of the traction force by vitrectomy, the use of long-acting gas as endotamponade, all contributed to the successful treatment of the disease. The pathogenic mechanisms of the disease and the function of B-scan to the diagnosis are included.

  5. Spectrally optimal illuminations for diabetic retinopathy detection in retinal imaging

    NASA Astrophysics Data System (ADS)

    Bartczak, Piotr; Fält, Pauli; Penttinen, Niko; Ylitepsa, Pasi; Laaksonen, Lauri; Lensu, Lasse; Hauta-Kasari, Markku; Uusitalo, Hannu

    2017-04-01

    Retinal photography is a standard method for recording retinal diseases for subsequent analysis and diagnosis. However, the currently used white light or red-free retinal imaging does not necessarily provide the best possible visibility of different types of retinal lesions, important when developing diagnostic tools for handheld devices, such as smartphones. Using specifically designed illumination, the visibility and contrast of retinal lesions could be improved. In this study, spectrally optimal illuminations for diabetic retinopathy lesion visualization are implemented using a spectrally tunable light source based on digital micromirror device. The applicability of this method was tested in vivo by taking retinal monochrome images from the eyes of five diabetic volunteers and two non-diabetic control subjects. For comparison to existing methods, we evaluated the contrast of retinal images taken with our method and red-free illumination. The preliminary results show that the use of optimal illuminations improved the contrast of diabetic lesions in retinal images by 30-70%, compared to the traditional red-free illumination imaging.

  6. Functional and anatomical remodeling in human retinal detachment.

    PubMed

    de Souza, Clairton F; Kalloniatis, Michael; Polkinghorne, Philip J; McGhee, Charles N J; Acosta, Monica L

    2012-04-01

    Rhegmatogenous retinal detachment is by far the most common indication for retinal surgery and a major cause of severe vision loss. Increased levels of glutamate found in the vitreous of human patients and persistent remodeling, even after reattachment, suggest substantial neurochemical, functional and anatomical changes have occurred in the detached retina. Therefore, this study was designed to characterize the morphological changes and glutamate receptor functionality in human rhegmatogenous retinal detachment. A cation channel permeating probe, agmatine (1-amino-4-guanidobutane; AGB), was employed to track endogenous and kainate (KA) driven channel functionality combined with immunocytochemical characterization of cellular remodeling. In the detached retina increased AGB permeability was identified in the outer retina while there was a decrease in the inner retina in basal conditions. KA receptors exhibited increased AGB permeability in ON bipolar cells and decreased permeability in calbindin labeled inner retinal cells. All retinal detachment samples demonstrated ectopic synaptic protein expression, photoreceptor processes extending toward the inner retina, and other remodeling features of retinal degeneration. These anatomical changes have been demonstrated in animal studies and are novel features unreported in primary cases of human retinal detachment. We conclude that deafferentation in retinal detachment leads to alteration of the glutamatergic pathway. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Peripheral 360 degrees retinectomy in complex retinal detachment.

    PubMed

    Banaee, Touka; Hosseini, Seyyedeh Maryam; Eslampoor, Alireza; Abrishami, Majid; Moosavi, Mirnaghi

    2009-06-01

    To report the functional and anatomical results and complications of 360 degrees peripheral retinectomy for management of complicated retinal detachment. Patients with complicated retinal detachment underwent pars plana vitrectomy, 360 degrees retinectomy, intraoperative endolaser, and internal tamponade with silicone oil. Postoperative visual acuity, intraocular pressure, retinal status, need for reoperation, and complications are presented. Twenty eyes of 19 patients with a mean age of 32.4 years (8-75 years) underwent pars plana vitrectomy and 360 degrees peripheral retinectomy for complicated retinal detachment due to anterior proliferative vitreoretinopathy, unstable edge of retinal break, anterior hyaloidal fibrovascular proliferation, retinal incarceration in scleral wound, and 300 degrees giant retinal tear. Intraoperative reattachment was achieved in 18 eyes. Mean postoperative follow-up time was 24.2 months (2-70 months). Retina was attached in 14 eyes (70%) in the last visit. Eight eyes (40%) had 5/200 or greater visual acuity. Preoperative and postoperative visual acuities did not have significant correlation (Spearman correlation coefficient = 0.291). There was no relation between diagnosis and anatomical outcome (P > 0.2). Relaxing peripheral 360 degrees retinectomy is an effective procedure for flattening the retina in complicated retinal detachments when no other option is available.

  8. Increased Prevalence of Flammer Syndrome in Patients with Retinitis Pigmentosa.

    PubMed

    Konieczka, K; Koch, S; Schoetzau, A; Todorova, M G

    2016-04-01

    "Retinitis pigmentosa" refers to a group of degenerative eye diseases with a genetic background. Flammer syndrome encompasses a set of symptoms and signs, mainly but not exclusively related to dysregulation of blood vessels. The purpose of the present study was to determine, with the help of a questionnaire, whether symptoms of Flammer syndrome occur more often in patients with retinitis pigmentosa than in controls. 76 patients with retinitis pigmentosa (members of the Swiss patient organization for retinitis pigmentosa) and 274 control subjects answered a questionnaire (Flammer Syndrome Questionnaire) on 15 symptoms and signs of Flammer syndrome. Seven of 15 symptoms and signs of Flammer syndrome were significantly more often positive in retinitis pigmentosa patients than in controls. Six additional symptoms and signs occurred non-significantly more often and 2 non-significantly less often in patients with retinitis pigmentosa. Retinitis pigmentosa patients suffer significantly more often from symptoms and signs of the Flammer syndrome than control subjects. This includes low body mass index, low blood pressure, feeling cold, migraine, increased smell perception and perfectionism. The reason for this association between retinitis pigmentosa and Flammer syndrome and the potential implications need to be determined. Georg Thieme Verlag KG Stuttgart · New York.

  9. Retinal oximeter for the blue-green oximetry technique

    NASA Astrophysics Data System (ADS)

    Denninghoff, Kurt R.; Sieluzycka, Katarzyna B.; Hendryx, Jennifer K.; Ririe, Tyson J.; Deluca, Lawrence; Chipman, Russell A.

    2011-10-01

    Retinal oximetry offers potential for noninvasive assessment of central venous oxyhemoglobin saturation (SO2) via the retinal vessels but requires a calibrated accuracy of +/-3% saturation in order to be clinically useful. Prior oximeter designs have been hampered by poor saturation calibration accuracy. We demonstrate that the blue-green oximetry (BGO) technique can provide accuracy within +/-3% in swine when multiply scattered light from blood within a retinal vessel is isolated. A noninvasive on-axis scanning retinal oximeter (ROx-3) is constructed that generates a multiwavelength image in the range required for BGO. A field stop in the detection pathway is used in conjunction with an anticonfocal bisecting wire to remove specular vessel reflections and isolate multiply backscattered light from the blood column within a retinal vessel. This design is tested on an enucleated swine eye vessel and a retinal vein in a human volunteer with retinal SO2 measurements of ~1 and ~65%, respectively. These saturations, calculated using the calibration line from earlier work, are internally consistent with a standard error of the mean of +/-2% SO2. The absolute measures are well within the expected saturation range for the site (-1 and 63%). This is the first demonstration of noninvasive on-axis BGO retinal oximetry.

  10. Epigenomics of Retinal Development in Mice and Humans.

    PubMed

    Lonfat, Nicolas; Cepko, Connie

    2017-05-03

    In this issue of Neuron, Aldiri et al. (2017) present an analysis of epigenetic changes during retinal development, and use these data to probe reprogramming of retinal iPSC cells, as well as the origin of retinoblastoma cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Retinal Photodamage Mediated by All-trans-retinal†

    PubMed Central

    Maeda, Tadao; Golczak, Marcin; Maeda, Akiko

    2012-01-01

    Accumulation of all-trans-retinal (all-trans-RAL), reactive vitamin A aldehyde, is one of the key factors in initiating retinal photodamage. This photodamage is characterized by progressive retinal cell death evoked by light exposure in both an acute and chronic fashion. Photo-activated rhodopsin releases all-trans-RAL which is subsequently transported by ATP–binding cassette transporter 4 and reduced to all-trans-retinol by all-trans-retinol dehydrogenases located in photoreceptor cells. Any interruptions in the clearing of all-trans-RAL in the photoreceptors can cause an accumulation of this reactive aldehyde and its toxic condensation products. This accumulation may result in the manifestation of retinal dystrophy including human retinal degenerative diseases such as Stargardt’s disease and age-related macular degeneration. Here, we discuss the mechanisms of all-trans-RAL clearance in photoreceptor cells by sequential enzymatic reactions, the visual (retinoid) cycle, and potential molecular pathways of retinal photodamage. We also review recent imaging technologies to monitor retinal health status as well as novel therapeutic strategies preventing all-trans-RAL-associated retinal photodamage. PMID:22428905

  12. The Edge Detectors Suitable for Retinal OCT Image Segmentation

    PubMed Central

    Yang, Jing; Gao, Qian; Zhou, Sheng

    2017-01-01

    Retinal layer thickness measurement offers important information for reliable diagnosis of retinal diseases and for the evaluation of disease development and medical treatment responses. This task critically depends on the accurate edge detection of the retinal layers in OCT images. Here, we intended to search for the most suitable edge detectors for the retinal OCT image segmentation task. The three most promising edge detection algorithms were identified in the related literature: Canny edge detector, the two-pass method, and the EdgeFlow technique. The quantitative evaluation results show that the two-pass method outperforms consistently the Canny detector and the EdgeFlow technique in delineating the retinal layer boundaries in the OCT images. In addition, the mean localization deviation metrics show that the two-pass method caused the smallest edge shifting problem. These findings suggest that the two-pass method is the best among the three algorithms for detecting retinal layer boundaries. The overall better performance of Canny and two-pass methods over EdgeFlow technique implies that the OCT images contain more intensity gradient information than texture changes along the retinal layer boundaries. The results will guide our future efforts in the quantitative analysis of retinal OCT images for the effective use of OCT technologies in the field of ophthalmology. PMID:29065594

  13. Accuracy of retinal oximetry: a Monte Carlo investigation

    PubMed Central

    Liu, Wenzhong; Jiao, Shuliang

    2013-01-01

    Abstract. Retinal hemoglobin oxygen saturation (sO2) level is believed to be associated with the pathophysiology of several leading blinding diseases. Methods to properly measure retinal sO2 have been investigated for decades; however, the accuracy of retinal oximetry is still considered to be limited. The Monte Carlo simulation of photon transport in retina to examine how the accuracy of retinal oximetry is affected by local parameters is discussed. Fundus photography was simulated in a multilayer retinal model, in which a single vessel segment with 0.7  sO2 was embedded, at six optical wavelengths. Then, 200 million photons were traced in each simulation to ensure statistically stable results. The optical reflectance and energy deposit were recorded to measure sO2 using both the reflection method (existing retinal oximetry) and a new absorption method, photoacoustic ophthalmoscopy (PAOM). By varying the vessel diameter and melanin concentration in the retinal pigment epithelium, the relative error of sO2 measurement in the reflection method increased with increasing vessel diameter and melanin concentration; in comparison, the sO2 measurement was insensitive to these two parameters in PAOM. The results suggest that PAOM potentially can be a more accurate tool in quantifying retinal sO2. PMID:23733019

  14. A Qualitative Self-Study of Retinitis Pigmentosa

    ERIC Educational Resources Information Center

    Fourie, Robert James

    2007-01-01

    Retinitis Pigmentosa (RP) is a retinal degenerative disease causing progressive blindness. Most research on RP is biomedical, and mostly from an observer perspective, therefore poorly reflecting the lived experience of having RP. Accordingly, the researcher conducted a retrospective qualitative self-study, to analyze reflections on his own…

  15. Retinal Remodeling: Concerns, Emerging Remedies and Future Prospects.

    PubMed

    Krishnamoorthy, Vidhyasankar; Cherukuri, Pitchaiah; Poria, Deepak; Goel, Manvi; Dagar, Sushma; Dhingra, Narender K

    2016-01-01

    Deafferentation results not only in sensory loss, but also in a variety of alterations in the postsynaptic circuitry. These alterations may have detrimental impact on potential treatment strategies. Progressive loss of photoreceptors in retinal degenerative diseases, such as retinitis pigmentosa and age-related macular degeneration, leads to several changes in the remnant retinal circuitry. Müller glial cells undergo hypertrophy and form a glial seal. The second- and third-order retinal neurons undergo morphological, biochemical and physiological alterations. A result of these alterations is that retinal ganglion cells (RGCs), the output neurons of the retina, become hyperactive and exhibit spontaneous, oscillatory bursts of spikes. This aberrant electrical activity degrades the signal-to-noise ratio in RGC responses, and thus the quality of information they transmit to the brain. These changes in the remnant retina, collectively termed "retinal remodeling", pose challenges for genetic, cellular and bionic approaches to restore vision. It is therefore crucial to understand the nature of retinal remodeling, how it affects the ability of remnant retina to respond to novel therapeutic strategies, and how to ameliorate its effects. In this article, we discuss these topics, and suggest that the pathological state of the retinal output following photoreceptor loss is reversible, and therefore, amenable to restorative strategies.

  16. Retinal vessel changes in galactose-fed dogs.

    PubMed

    Kobayashi, T; Kubo, E; Takahashi, Y; Kasahara, T; Yonezawa, H; Akagi, Y

    1998-06-01

    Retinal lesions similar to those in human early-stage diabetic retinopathy have been reported to occur in dogs fed galactose for long periods. Investigations of retinal changes, however, have been limited to studies of the intact retinal vasculature isolated by trypsin digestion. To document the onset and progression of retinal lesions in galactose-fed dogs by the common clinical techniques of fundus color photography and fluorescein angiography. Fourteen 6-month-old male beagles made aphakic in 1 eye were divided into a control group (4 dogs), receiving a diet containing 30% cellulose, and a galactosemic group (10 dogs), receiving a diet containing 30% galactose. The progression of retinal changes in these dogs was periodically monitored by color fundus photography and fluorescein angiography. Dogs fed a 30% galactose diet for 28 to 41 months were observed by fluorescein angiography and color fundus photography to develop, in order of frequency, microaneurysms, retinal hemorrhages, intraretinal microvascular abnormalities, retinal nonperfused areas, and varicose and serpiginous veins. These findings are similar to the early clinical retinal changes observed in humans with diabetes. These results confirm that galactosemic dogs are an appropriate and suitable animal model for investigating human diabetic retinopathy.

  17. Deblurring adaptive optics retinal images using deep convolutional neural networks.

    PubMed

    Fei, Xiao; Zhao, Junlei; Zhao, Haoxin; Yun, Dai; Zhang, Yudong

    2017-12-01

    The adaptive optics (AO) can be used to compensate for ocular aberrations to achieve near diffraction limited high-resolution retinal images. However, many factors such as the limited aberration measurement and correction accuracy with AO, intraocular scatter, imaging noise and so on will degrade the quality of retinal images. Image post processing is an indispensable and economical method to make up for the limitation of AO retinal imaging procedure. In this paper, we proposed a deep learning method to restore the degraded retinal images for the first time. The method directly learned an end-to-end mapping between the blurred and restored retinal images. The mapping was represented as a deep convolutional neural network that was trained to output high-quality images directly from blurry inputs without any preprocessing. This network was validated on synthetically generated retinal images as well as real AO retinal images. The assessment of the restored retinal images demonstrated that the image quality had been significantly improved.

  18. Deblurring adaptive optics retinal images using deep convolutional neural networks

    PubMed Central

    Fei, Xiao; Zhao, Junlei; Zhao, Haoxin; Yun, Dai; Zhang, Yudong

    2017-01-01

    The adaptive optics (AO) can be used to compensate for ocular aberrations to achieve near diffraction limited high-resolution retinal images. However, many factors such as the limited aberration measurement and correction accuracy with AO, intraocular scatter, imaging noise and so on will degrade the quality of retinal images. Image post processing is an indispensable and economical method to make up for the limitation of AO retinal imaging procedure. In this paper, we proposed a deep learning method to restore the degraded retinal images for the first time. The method directly learned an end-to-end mapping between the blurred and restored retinal images. The mapping was represented as a deep convolutional neural network that was trained to output high-quality images directly from blurry inputs without any preprocessing. This network was validated on synthetically generated retinal images as well as real AO retinal images. The assessment of the restored retinal images demonstrated that the image quality had been significantly improved. PMID:29296496

  19. Retinal oximeter for the blue-green oximetry technique

    PubMed Central

    Denninghoff, Kurt R.; Sieluzycka, Katarzyna B.; Hendryx, Jennifer K.; Ririe, Tyson J.; DeLuca, Lawrence; Chipman, Russell A.

    2011-01-01

    Retinal oximetry offers potential for noninvasive assessment of central venous oxyhemoglobin saturation (SO2) via the retinal vessels but requires a calibrated accuracy of ±3% saturation in order to be clinically useful. Prior oximeter designs have been hampered by poor saturation calibration accuracy. We demonstrate that the blue-green oximetry (BGO) technique can provide accuracy within ±3% in swine when multiply scattered light from blood within a retinal vessel is isolated. A noninvasive on-axis scanning retinal oximeter (ROx-3) is constructed that generates a multiwavelength image in the range required for BGO. A field stop in the detection pathway is used in conjunction with an anticonfocal bisecting wire to remove specular vessel reflections and isolate multiply backscattered light from the blood column within a retinal vessel. This design is tested on an enucleated swine eye vessel and a retinal vein in a human volunteer with retinal SO2 measurements of ∼1 and ∼65%, respectively. These saturations, calculated using the calibration line from earlier work, are internally consistent with a standard error of the mean of ±2% SO2. The absolute measures are well within the expected saturation range for the site (–1 and 63%). This is the first demonstration of noninvasive on-axis BGO retinal oximetry. PMID:22029366

  20. The Edge Detectors Suitable for Retinal OCT Image Segmentation.

    PubMed

    Luo, Su; Yang, Jing; Gao, Qian; Zhou, Sheng; Zhan, Chang'an A

    2017-01-01

    Retinal layer thickness measurement offers important information for reliable diagnosis of retinal diseases and for the evaluation of disease development and medical treatment responses. This task critically depends on the accurate edge detection of the retinal layers in OCT images. Here, we intended to search for the most suitable edge detectors for the retinal OCT image segmentation task. The three most promising edge detection algorithms were identified in the related literature: Canny edge detector, the two-pass method, and the EdgeFlow technique. The quantitative evaluation results show that the two-pass method outperforms consistently the Canny detector and the EdgeFlow technique in delineating the retinal layer boundaries in the OCT images. In addition, the mean localization deviation metrics show that the two-pass method caused the smallest edge shifting problem. These findings suggest that the two-pass method is the best among the three algorithms for detecting retinal layer boundaries. The overall better performance of Canny and two-pass methods over EdgeFlow technique implies that the OCT images contain more intensity gradient information than texture changes along the retinal layer boundaries. The results will guide our future efforts in the quantitative analysis of retinal OCT images for the effective use of OCT technologies in the field of ophthalmology.

  1. 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

  2. Automated retinal fovea type distinction in spectral-domain optical coherence tomography of retinal vein occlusion

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    Spectral-domain Optical Coherence Tomography (SD-OCT) is a non-invasive modality for acquiring high- resolution, 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), glaucoma and retinal vein occlusion (RVO). Disease diagnosis, assessment, and treatment will require a patient to undergo multiple OCT scans, possibly using multiple scanners, to accurately and precisely gauge disease activity, progression and treatment success. However, cross-vendor imaging and patient movement may result in poor scan spatial correlation potentially leading to incorrect diagnosis or treatment analysis. The retinal fovea is the location of the highest visual acuity and is present in all patients, thus it is critical to vision and highly suitable for use as a primary landmark for cross-vendor/cross-patient registration for precise comparison of disease states. However, the location of the fovea in diseased eyes is extremely challenging to locate due to varying appearance and the presence of retinal layer destroying pathology. Thus categorising and detecting the fovea type is an important prior stage to automatically computing the fovea position. Presented here is an automated cross-vendor method for fovea distinction in 3D SD-OCT scans of patients suffering from RVO, categorising scans into three distinct types. OCT scans are preprocessed by motion correction and noise filing followed by segmentation using a kernel graph-cut approach. A statistically derived mask is applied to the resulting scan creating an ROI around the probable fovea location from which the uppermost retinal surface is delineated. For a normal appearance retina, minimisation to zero thickness is computed using the top two retinal surfaces. 3D local minima detection and layer thickness analysis are used

  3. 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%.

  4. Course of Ocular Function in PRPF31 Retinitis Pigmentosa.

    PubMed

    Hafler, Brian P; Comander, Jason; Weigel DiFranco, Carol; Place, Emily M; Pierce, Eric A

    2016-01-01

    Mutations in pre-mRNA splicing factors are the second most common cause of autosomal dominant retinitis pigmentosa, and a major cause of vision loss. The development of gene augmentation therapy for disease caused by mutations in PRPF31 necessitates defining pretreatment characteristics and disease progression of patients with PRPF31-related retinitis pigmentosa. We show rates of decline of visual field area -6.9% per year and 30-Hz flicker cone response of -9.2% per year, which are both similar to observed rates for retinitis pigmentosa. We hypothesize that RNA splicing factor retinitis pigmentosa will be amenable to treatment by AAV-mediated gene therapy, and that understanding the clinical progression rates of PRPF31 retinitis pigmentosa will help with the design of gene therapy clinical trials.

  5. Intrinsic optical signal imaging of retinal physiology: a review.

    PubMed

    Yao, Xincheng; Wang, Benquan

    2015-09-01

    Intrinsic optical signal (IOS) imaging promises to be a noninvasive method for high-resolution examination of retinal physiology, which can advance the study and diagnosis of eye diseases. While specialized optical instruments are desirable for functional IOS imaging of retinal physiology, in depth understanding of multiple IOS sources in the complex retinal neural network is essential for optimizing instrument designs. We provide a brief overview of IOS studies and relationships in rod outer segment suspensions, isolated retinas, and intact eyes. Recent developments of line-scan confocal and functional optical coherence tomography (OCT) instruments have allowed in vivo IOS mapping of photoreceptor physiology. Further improvements of the line-scan confocal and functional OCT systems may provide a feasible solution to pursue functional IOS mapping of human photoreceptors. Some interesting IOSs have already been detected in inner retinal layers, but better development of the IOS instruments and software algorithms is required to achieve optimal physiological assessment of inner retinal neurons.

  6. Intrinsic optical signal imaging of retinal physiology: a review

    NASA Astrophysics Data System (ADS)

    Yao, Xincheng; Wang, Benquan

    2015-09-01

    Intrinsic optical signal (IOS) imaging promises to be a noninvasive method for high-resolution examination of retinal physiology, which can advance the study and diagnosis of eye diseases. While specialized optical instruments are desirable for functional IOS imaging of retinal physiology, in depth understanding of multiple IOS sources in the complex retinal neural network is essential for optimizing instrument designs. We provide a brief overview of IOS studies and relationships in rod outer segment suspensions, isolated retinas, and intact eyes. Recent developments of line-scan confocal and functional optical coherence tomography (OCT) instruments have allowed in vivo IOS mapping of photoreceptor physiology. Further improvements of the line-scan confocal and functional OCT systems may provide a feasible solution to pursue functional IOS mapping of human photoreceptors. Some interesting IOSs have already been detected in inner retinal layers, but better development of the IOS instruments and software algorithms is required to achieve optimal physiological assessment of inner retinal neurons.

  7. Retinal origin of direction selectivity in the superior colliculus.

    PubMed

    Shi, Xuefeng; Barchini, Jad; Ledesma, Hector Acaron; Koren, David; Jin, Yanjiao; Liu, Xiaorong; Wei, Wei; Cang, Jianhua

    2017-04-01

    Detecting visual features in the environment, such as motion direction, is crucial for survival. The circuit mechanisms that give rise to direction selectivity in a major visual center, the superior colliculus (SC), are entirely unknown. We optogenetically isolate the retinal inputs that individual direction-selective SC neurons receive and find that they are already selective as a result of precisely converging inputs from similarly tuned retinal ganglion cells. The direction-selective retinal input is linearly amplified by intracollicular circuits without changing its preferred direction or level of selectivity. Finally, using two-photon calcium imaging, we show that SC direction selectivity is dramatically reduced in transgenic mice that have decreased retinal selectivity. Together, our studies demonstrate a retinal origin of direction selectivity in the SC and reveal a central visual deficit as a consequence of altered feature selectivity in the retina.

  8. Nondiabetic retinal pathology - prevalence in diabetic retinopathy screening.

    PubMed

    Nielsen, Nathan; Jackson, Claire; Spurling, Geoffrey; Cranstoun, Peter

    2011-07-01

    To determine the prevalence of photographic signs of nondiabetic retinal pathology in Australian general practice patients with diabetes. Three hundred and seven patients with diabetes underwent retinal photography at two general practices, one of which was an indigenous health centre. The images were assessed for signs of pathology by an ophthalmologist. Signs of nondiabetic retinal pathology were detected in 31% of subjects with adequate photographs. Features suspicious of glaucoma were detected in 7.7% of subjects. Other abnormalities detected included signs of age related macular degeneration (1.9%), epiretinal membranes (2.4%), vascular pathology (9.6%), chorioretinal lesions (2.9%), and congenital disc anomalies (2.9%). Indigenous Australian patients were more likely to have signs of retinal pathology and glaucoma. Signs of nondiabetic retinal pathology were frequently encountered. In high risk groups, general practice based diabetic retinopathy screening may reduce the incidence of preventable visual impairment, beyond the benefits of detection of diabetic retinopathy alone.

  9. The cost-effectiveness of the Argus II retinal prosthesis in Retinitis Pigmentosa patients

    PubMed Central

    2014-01-01

    Background Retinitis Pigmentosa (RP) is a hereditary genetic disease causing bilateral retinal degeneration. RP is a leading cause of blindness resulting in incurable visual impairment and drastic reduction in the Quality of life of the patients. Second Sight Medical Products Inc. developed Argus II, a retinal prosthesis system for treating RP. Argus II is the world’s first ever-commercial implant intended to restore some vision in the blind patients. The objective of this study was to assess the cost-effectiveness of the Argus® II Retinal Prosthesis System (Argus II) in Retinitis Pigmentosa (RP) patients. Method A multi -state transition Markov model was developed to determine the cost-effectiveness of Argus II versus usual care in RP from the perspective of healthcare payer. A hypothetical cohort of 1000 RP patients aged 46 years followed up over a (lifetime) 25-year time horizon. Health outcomes were expressed as quality adjusted life years (QALYs) and direct healthcare costs expressed in 2012 €. Results are reported as incremental cost per ratios (ICERs) with outcomes and costs discounted at an annual rate of 3.5%. Results The ICER for Argus II was €14,603/QALY. Taking into account the uncertainty in model inputs the ICER was €14,482/QALY in the probabilistic analysis. In the scenarios of an assumption of no reduction on cost across model visual acuity states or a model time horizon as short as 10 years the ICER increased to €31,890/QALY and €49,769/QALY respectively. Conclusion This economic evaluation shows that Argus II is a cost-effective intervention compared to usual care of the RP patients. The lifetime analysis ICER for Argus II falls below the published societal willingness to pay of EuroZone countries. PMID:24731533

  10. Towards real time speckle controlled retinal photocoagulation

    NASA Astrophysics Data System (ADS)

    Bliedtner, Katharina; Seifert, Eric; Stockmann, Leoni; Effe, Lisa; Brinkmann, Ralf

    2016-03-01

    Photocoagulation is a laser treatment widely used for the therapy of several retinal diseases. Intra- and inter-individual variations of the ocular transmission, light scattering and the retinal absorption makes it impossible to achieve a uniform effective exposure and hence a uniform damage throughout the therapy. A real-time monitoring and control of the induced damage is highly requested. Here, an approach to realize a real time optical feedback using dynamic speckle analysis is presented. A 532 nm continuous wave Nd:YAG laser is used for coagulation. During coagulation, speckle dynamics are monitored by a coherent object illumination using a 633nm HeNe laser and analyzed by a CMOS camera with a frame rate up to 1 kHz. It is obvious that a control system needs to determine whether the desired damage is achieved to shut down the system in a fraction of the exposure time. Here we use a fast and simple adaption of the generalized difference algorithm to analyze the speckle movements. This algorithm runs on a FPGA and is able to calculate a feedback value which is correlated to the thermal and coagulation induced tissue motion and thus the achieved damage. For different spot sizes (50-200 μm) and different exposure times (50-500 ms) the algorithm shows the ability to discriminate between different categories of retinal pigment epithelial damage ex-vivo in enucleated porcine eyes. Furthermore in-vivo experiments in rabbits show the ability of the system to determine tissue changes in living tissue during coagulation.

  11. Ethnic variation in rhegmatogenous retinal detachments

    PubMed Central

    Chandra, A; Banerjee, P; Davis, D; Charteris, D

    2015-01-01

    Purpose We aimed to investigate the clinical variation of rhegmatogenous retinal detachments (RD) in patients of different ethnicities. Methods Patients presenting with a primary RD from two ethnic groups were recruited from our tertiary referral hospital between August 2010 and December 2012. Patients who self-reported their ethnic origin either as European Caucasian (EC) or South Asian (SA) were included. Exclusion criteria included trauma, previous vitreoretinal procedures, age under 18 years, complicated cataract surgery and the presence of syndromes known to be associated with a high prevalence of RD. Detailed phenotypic data were collected. Descriptive and comparative statistical analyses were undertaken. Results 1269 Patients were recruited. 1173 (92.4%) were EC. Mean age of onset was 58.3 years (EC) and 54.5 years (SA) (P=0.006). 75.3% EC and 58.4% SA were phakic (P<0.001). 12.8% of EC and 19.4% of SA patients had a lattice retinal degeneration in the affected eye (P=0.003). Refractive myopia was greater in SA patients (mean: −6.1DS) than EC (−4.2DS) (P=0.032). Additionally, SA patients had a greater mean axial length (25.65 mm) than EC (25.06 mm) (P=0.014). No differences were demonstrated in laterality, family history, type of retinal break or macular status. Conclusions SA patients present with RD at an earlier age and have a more severe phenotype than ECs. Future management strategies for RD may need to reflect these differences. PMID:25853394

  12. Computing retinal contour from optical biometry.

    PubMed

    Faria-Ribeiro, Miguel; López-Gil, Norberto; Navarro, Rafael; Lopes-Ferreira, Daniela; Jorge, Jorge; González-Méijome, Jose Manuel

    2014-04-01

    To describe a new methodology that derives horizontal posterior retinal contours from partial coherence interferometry (PCI) and ray tracing using the corneal topography. Corneal topography and PCI for seven horizontal visual field eccentricities correspondent to the central 60 degrees of the posterior pole were obtained in 55 myopic eyes. A semicustomized eye model based on the subject's corneal topography and the Navarro eye model was generated using Zemax-EE software. The model was used to compute the optical path length in the seven directions where PCI measurements were obtained. Vitreous chamber depth was computed using the PCI values obtained at each of those directions. Matlab software was developed to fit the best conic curve to the set of points previously obtained. We tested the limit in the accuracy of the methodology when the actual cornea of the subject is not used and for two different lens geometries. A standard eye model can induce an error in the retina sagitta estimation of the order of hundreds of micrometers in comparison with the semicustomized eye model. However, the use of a different lens model leads to an error of the order of tens of micrometers. The apical radius and conic constant of the average fit were -11.91 mm and -0.15, respectively. In general, a nasal-temporal asymmetry in the retina contour was found, showing mean larger values of vitreous chamber depth in the nasal side of the eye. The use of a semicustomized eye model, together with optical path length measured by PCI for different angles, can be used to predict the retinal contour within tenths of micrometers. This methodology can be useful in studies trying to understand the effect of peripheral retinal location on myopia progression as well as modeling the optics of the human eye for a wide field.

  13. Gene therapy for inherited retinal degenerations.

    PubMed

    Dalkara, Deniz; Sahel, José-Alain

    2014-03-01

    Gene therapy is quickly becoming a reality applicable in the clinic for inherited retinal diseases. Progress over the past decade has moved proof-of-concept gene therapies from bench to bedside. The remarkable success in safety and efficacy, in the phase I/II clinical trials for the form of the severe childhood-onset blindness, Leber's Congenital Amaurosis (LCA) type II (due to mutations in the RPE65 gene) generated significant interest and opened up possibilities for a new era of retinal gene therapies. Success in these clinical trials was due to combining the favorable features of both the retina as a target organ and adeno-associated virus (AAV) as a vector. The retina offers several advantages for gene therapy approaches. It is an anatomically defined structure that is readily accessible for therapy and has some degree of immune privilege, making it suitable for application of viral vectors. AAV, on the other hand, is a non-pathogenic helper dependent virus that has little immunogenicity. This viral vector transduces quiescent cells efficiently and thanks to its small size diffuses well in the interneural matrix, making it suitable for applications in neural tissue. Building on this initial clinical success with LCA II, we have now many opportunities to extend this proof-of-concept to other retinal diseases. This article will discuss what are some of the most imminent targets for such therapies and what are the challenges that we face in moving these therapies to the clinic. Copyright © 2014 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  14. Balance between autophagic pathways preserves retinal homeostasis

    PubMed Central

    Natalia-Rodríguez-Muela; Koga, Hiroshi; García-Ledo, Lucía; de la Villa, Pedro; de la Rosa, Enrique J.; Cuervo, Ana María; Boya, Patricia

    2013-01-01

    Summary Aging contributes to the appearance of several retinopathies and is the largest risk factor for aged-related macular degeneration, major cause of blindness in the elderly population. Accumulation of undegraded material as lipofuscin represents a hallmark in many pathologies of the aged eye. Autophagy is a highly conserved intracellular degradative pathway that plays a critical role in the removal of damaged cell components to maintain the cellular homeostasis. A decrease in autophagic activity with age observed in many tissues has been proposed to contribute to the aggravation of age-related diseases. However, the participation of different autophagic pathways to the retina physiopathology remains unknown. Here we describe a marked reduction in macroautophagic activity in the retina with age, which coincides with an increase in chaperone-mediated autophagy (CMA). This increase in CMA is also observed during retinal neurodegeneration in the Atg5flox/flox; nestin-Cre mice, a mouse model with downregulation of macroautophagy in neuronal precursors. In contrast to other cell types, this autophagic cross-talk in retinal cells is not bi-directional and CMA inhibition renders cone photoreceptor very sensitive to stress. Temporal and cell-type specific differences in the balance between autophagic pathways may be responsible for the specific pattern of visual loss that occurs with aging. Our results show for the first time a cross-talk of different lysosomal proteolytic systems in the retina during normal aging and may help the development of new therapeutic intervention for age-dependent retinal diseases. PMID:23521856

  15. Patterned retinal coagulation with a scanning laser

    NASA Astrophysics Data System (ADS)

    Palanker, Daniel; Jain, ATul; Paulus, Yannis; Andersen, Dan; Blumenkranz, Mark S.

    2007-02-01

    Pan-retinal photocoagulation in patients with diabetic retinopathy typically involves application of more than 1000 laser spots; often resulting in physician fatigue and patient discomfort. We present a semi-automated patterned scanning laser photocoagulator that rapidly applies predetermined patterns of lesions; thus, greatly improving the comfort, efficiency and precision of the treatment. Patterns selected from a graphical user interface are displayed on the retina with an aiming beam, and treatment can be initiated and interrupted by depressing a foot pedal. To deliver a significant number of burns during the eye's fixation time, each pulse should be considerably shorter than conventional 100ms pulse duration. We measured coagulation thresholds and studied clinical and histological outcomes of the application of laser pulses in the range of 1-200ms in pigmented rabbits. Laser power required for producing ophthalmoscopically visible lesions with a laser spot of 132μm decreased from 360 to 37mW with pulse durations increasing from 1 to 100ms. In the range of 10-100ms clinically and histologically equivalent light burns could be produced. The safe therapeutic range of coagulation (ratio of the laser power required to produce a rupture to that for a light burn) decreased with decreasing pulse duration: from 3.8 at 100ms, to 3.0 at 20ms, to 2.5 at 10ms, and to 1.1 at 1ms. Histology demonstrated increased confinement of the thermal damage with shorter pulses, with coagulation zone limited to the photoreceptor layer at pulses shorter than 10ms. Durations of 10-20ms appear to be a good compromise between the speed and safety of retinal coagulation. Rapid application of multiple lesions greatly improves the speed, precision, and reduces pain in retinal photocoagulation.

  16. 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.

  17. Developing Cellular Therapies for Retinal Degenerative Diseases

    PubMed Central

    Bharti, Kapil; Rao, Mahendra; Hull, Sara Chandros; Stroncek, David; Brooks, Brian P.; Feigal, Ellen; van Meurs, Jan C.; Huang, Christene A.; Miller, Sheldon S.

    2014-01-01

    Biomedical advances in vision research have been greatly facilitated by the clinical accessibility of the visual system, its ease of experimental manipulation, and its ability to be functionally monitored in real time with noninvasive imaging techniques at the level of single cells and with quantitative end-point measures. A recent example is the development of stem cell–based therapies for degenerative eye diseases including AMD. Two phase I clinical trials using embryonic stem cell–derived RPE are already underway and several others using both pluripotent and multipotent adult stem cells are in earlier stages of development. These clinical trials will use a variety of cell types, including embryonic or induced pluripotent stem cell–derived RPE, bone marrow– or umbilical cord–derived mesenchymal stem cells, fetal neural or retinal progenitor cells, and adult RPE stem cells–derived RPE. Although quite distinct, these approaches, share common principles, concerns and issues across the clinical development pipeline. These considerations were a central part of the discussions at a recent National Eye Institute meeting on the development of cellular therapies for retinal degenerative disease. At this meeting, emphasis was placed on the general value of identifying and sharing information in the so-called “precompetitive space.” The utility of this behavior was described in terms of how it could allow us to remove road blocks in the clinical development pipeline, and more efficiently and economically move stem cell–based therapies for retinal degenerative diseases toward the clinic. Many of the ocular stem cell approaches we discuss are also being used more broadly, for nonocular conditions and therefore the model we develop here, using the precompetitive space, should benefit the entire scientific community. PMID:24573369

  18. Histogenesis of retinal dysplasia in trisomy 13

    PubMed Central

    Chan, Ada; Lakshminrusimha, Satyan; Heffner, Reid; Gonzalez-Fernandez, Federico

    2007-01-01

    Background Although often associated with holoprosencephaly, little detail of the histopathology of cyclopia is available. Here, we describe the ocular findings in a case of trisomy 13 to better understand the histogenesis of the rosettes, or tubules, characteristic of the retinal dysplasia associated with this condition. Methods A full pediatric autopsy was performed of a near term infant who died shortly after birth from multiple congenital anomalies including fused facial-midline structures. A detailed histopathological study of the ocular structures was performed. The expression of interphotoreceptor retinoid-binding protein (IRBP), cellular retinal-binding protein (CRALBP), rod opsin, and Sonic Hedgehog (Shh) were studied by immunohistochemistry. Results Holoprosencephaly, and a spectrum of anatomical findings characteristic of Patau's syndrome, were found. Cytogenetic studies demonstrated trisomy 13 [47, XY, +13]. The eyes were fused but contained two developed separate lenses. In contrast, the cornea, and angle structures were hypoplastic, and the anterior chamber had failed to form. The retina showed areas of normally laminated neural retina, whereas in other areas it was replaced by numerous neuronal rosettes. Histological and immunohistochemical studies revealed that the rosettes were composed of differentiated retinal neurons and Müller cell glia. In normally laminated retina, Shh expression was restricted to retinal-ganglion cells, and to a population of neurons in the inner zone of the outer nuclear layer. In contrast, Shh could not be detected in the dysplastic rosettes. Conclusion The histopathology of cyclopia appears to be more complex than what may have been previously appreciated. In fact, the terms "cyclopia" and "synophthalmia" are misnomers as the underlying mechanism is a failure of the eyes to form separately during development. The rosettes found in the dysplastic retina are fundamentally different than those of retinoblastoma, being

  19. Programming Retinal Stem Cells into Cone Photoreceptors

    DTIC Science & Technology

    2015-12-01

    photoreceptor gene, Otx2. Two of these genes appeared to promote Otx2 expression in the developing mouse retina . These results provided a key link between...reverse vision loss. 15. SUBJECT TERMS Cone photoreceptor, retina , retinal stem cell, Otx2, Onecut1, Blimp1, RNA-seq., transcription factors, and...12 9. Appendices……………………………………………………………13-16 Introduction: The cone photoreceptors of the retina are required for high acuity and color

  20. Digital Tracking and Control of Retinal Images

    DTIC Science & Technology

    1993-05-01

    this exciting project. Your work has formed the basis for this research and many others. At UT I have made many friends. I would like to thank Chris...17 years of my life. You worked harder than I did these past three years keeping everybody happy. I love you. This research was sponsored in part by...the Texas Coordinating Board and in part by the Office of Naval Research under grant N00014-91-J-1564. v DIGITAL TRACKING AND CONTROL OF RETINAL IMAGES

  1. The Role of Cytochrome P450 Epoxygenases in Retinal Angiogenesis

    PubMed Central

    Capozzi, Megan E.; McCollum, Gary W.; Penn, John S.

    2014-01-01

    Purpose. The purpose of this study was to investigate the role(s) of cytochrome P450 epoxygenases (CYPs) and their products, the epoxyeicosatrienoic acids (EETs), in hypoxia-induced VEGF production and pathologic retinal angiogenesis. Methods. Human retinal astrocytes, Müller cells, and retinal microvascular endothelial cells (HRMEC) were exposed to hypoxia, and relative CYP2C expression was measured by RT-PCR. Astrocyte and Müller cell VEGF production was measured by ELISA after exposure to hypoxia and treatment with the general CYP inhibitor, SKF-525a. Human retinal microvascular endothelial cells were treated with the CYP product, 11,12-epoxyeicosatrienoic acid [EET], or SKF-525a in the presence or absence of VEGF. Proliferation of HRMEC and tube formation were assayed. Oxygen-induced retinopathy (OIR) was induced in newborn rats. Retinal CYP2C11 and CYP2C23 expression were measured by RT-PCR. The OIR rats received SKF-525a by intravitreal injection and p