Fan, Ting-jun; Zhao, Jun; Hu, Xiu-zhong; Ma, Xi-ya; Zhang, Wen-bo; Yang, Chao-zhong
To evaluate the therapeutic efficiency of tissue-engineered human corneal endothelia (TE-HCEs) on rabbit primary corneal endotheliopathy (PCEP), TE-HCEs reconstructed with monoclonal human corneal endothelial cells (mcHCECs) and modified denuded amniotic membranes (mdAMs) were transplanted into PCEP models of New Zealand white rabbits using penetrating keratoplasty. The TE-HCEs were examined using diverse techniques including slit-lamp biomicroscopy observation and pachymeter and tonometer measurements in vivo, and fluorescent microscopy, alizarin red staining, paraffin sectioning, scanning and transmission electron microscopy observations in vitro. The corneas of transplanted eyes maintained transparency for as long as 200 d without obvious edema or immune rejection. The corneal thickness of transplanted eyes decreased gradually after transplanting, reaching almost the thickness of normal eyes after 156 d, while the TE-HCE non-transplanted eyes were turbid and showed obvious corneal edema. The polygonal corneal endothelial cells in the transplanted area originated from the TE-HCE transplant. An intact monolayer corneal endothelium had been reconstructed with the morphology, cell density and structure similar to those of normal rabbit corneal endothelium. In conclusion, the transplanted TE-HCE can reconstruct the integrality of corneal endothelium and restore corneal transparency and thickness in PCEP rabbits. The TE-HCE functions normally as an endothelial barrier and pump and promises to be an equivalent of HCE for clinical therapy of human PCEP.
Morbidelli, Lucia; Ziche, Marina
The rabbit corneal micropocket angiogenesis assay uses the avascular cornea as a substrate canvas to study angiogenesis in vivo. Through the use of standardized slow-release pellets, a predictable angiogenic response is generated over the course of 1-2 weeks and then quantified. Uniform slow-release pellets are prepared by mixing purified angiogenic growth factors such as basic fibroblast growth factor or vascular endothelial growth factor and a synthetic polymer to allow slow release. A micropocket is surgically created in the rabbit cornea under anesthesia and a pellet implanted. On the days later, the angiogenic response is measured and qualified using a slit lamp, as well as the concomitant vascular phenotype or inflammatory features. The results of the assay are used to assess the ability of potential therapeutic molecules to modulate angiogenesis in vivo, both when released locally or given by ocular formulations or through systemic treatment. In this chapter, the experimental details of the rabbit cornea assay and technical implementations to the original protocol are described.
Yin, Houfa; Qiu, Peijin; Wu, Fang; Zhang, Wei; Teng, Wenqi; Qin, Zhenwei; Li, Chao; Zhou, Jiaojie; Fang, Zhi; Tang, Qiaomei; Fu, Qiuli; Ma, Jian; Yang, Yabo
The scarcity of corneal tissue to treat deep corneal defects and corneal perforations remains a challenge. Currently, small incision lenticule extraction (SMILE)-derived lenticules appear to be a promising alternative for the treatment of these conditions. However, the thickness and toughness of a single piece of lenticule are limited. To overcome these limitations, we constructed a corneal stromal equivalent with SMILE-derived lenticules and fibrin glue. In vitro cell culture revealed that the corneal stromal equivalent could provide a suitable scaffold for the survival and proliferation of corneal epithelial cells, which formed a continuous pluristratified epithelium with the expression of characteristic markers. Finally, anterior lamellar keratoplasty in rabbits demonstrated that the corneal stromal equivalent with decellularized lenticules and fibrin glue could repair the anterior region of the stroma, leading to re-epithelialization and recovery of both transparency and ultrastructural organization. Corneal neovascularization, graft degradation, and corneal rejection were not observed within 3 months. Taken together, the corneal stromal equivalent with SMILE-derived lenticules and fibrin glue appears to be a safe and effective alternative for the repair of damage to the anterior cornea, which may provide new avenues in the treatment of deep corneal defects or corneal perforations. PMID:27651001
Avila, Marcel Y; Narvaez, Mauricio; Castañeda, Juan P
To evaluate the effect of genipin, a natural crosslinking agent, in rabbit eyes. Department of Ophthalmology, Universidad Nacional de Colombia Centro de Tecnologia Oftalmica, Bogotá, Colombia. Experimental study. Ex vivo rabbit eyes (16; 8 rabbits) were treated with genipin 1.00%, 0.50%, and 0.25% for 5 minutes with a vacuum device to increase corneal permeability. Penetration was evaluated using Scheimpflug pachymetry (Pentacam). In the in vivo model (20 rabbits; 1 eye treated, 1 eye with vehicle), corneas were crosslinked with genipin as described. Corneal curvature, corneal pachymetry, and intraocular pressure (IOP) assessments as well as slitlamp examinations were performed 0, 7, 30, and 60 days after treatment. In the ex vivo model, Scheimpflug pachymetry showed deep penetration in the rabbit corneas with an increase in corneal density and a dose-dependent relationship. Corneal flattening was observed in treated eyes (mean 4.4 diopters ± 0.5 [SD]) compared with the control eyes. Pachymetry and IOP were stable in all evaluations. No eye showed toxicity in the anterior chamber or in the lens. Corneal crosslinking induced by genipin produced significant flattening of the cornea with no toxicity in rabbit eyes. This crosslinking could be useful in the treatment of corneal ectasia and in the modification of corneal curvature. None of the authors has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.
Zhang, Zhenhao; Huang, Yue; Xie, Hui; Pan, Juxin; Liu, Fanfei; Li, Xuezhi; Chen, Wensheng; Hu, Jiaoyue; Liu, Zuguo
Purpose Gap junction intercellular communication (GJIC) plays a critical role in the maintenance of corneal endothelium homeostasis. We determined if benzalkonium chloride (BAK) alters GJIC activity in the rabbit corneal endothelium since it is commonly used as a drug preservative in ocular eyedrop preparations even though it can have cytotoxic effects. Methods Thirty-six adult New Zealand albino rabbits were randomly divided into three groups. BAK at 0.01%, 0.05%, and 0.1% was applied twice daily to one eye of each of the rabbits in one of the three groups for seven days. The contralateral untreated eyes were used as controls. Corneal endothelial morphological features were observed by in vivo confocal microscopy (IVCM). Immunofluorescent staining resolved changes in gap junction integrity and localization. Western blot analysis and RT-PCR evaluated changes in levels of connexin43 (Cx43) and tight junction zonula occludens-1 (ZO-1) gene and protein expression, respectively. Cx43 and ZO-1 physical interaction was detected by immunoprecipitation (IP). Primary rabbit corneal endothelial cells were cultured in Dulbecco's Modified Eagle Medium (DMEM) containing BAK for 24 hours. The scrape-loading dye transfer technique (SLDT) was used to assess GJIC activity. Results Topical administration of BAK (0.05%, 0.1%) dose dependently disrupted corneal endothelial cell morphology, altered Cx43 and ZO-1 distribution and reduced Cx43 expression. BAK also markedly induced increases in Cx43 phosphorylation status concomitant with decreases in the Cx43-ZO-1 protein-protein interaction. These changes were associated with marked declines in GJIC activity. Conclusions The dose dependent declines in rabbit corneal endothelial GJIC activity induced by BAK are associated with less Cx43-ZO-1 interaction possibly arising from increases in Cx43 phosphorylation and declines in its protein expression. These novel changes provide additional evidence that BAK containing eyedrop preparations
Kim, Jeong-Ah; Ko, Jung Hwa; Ko, Ah Young; Lee, Hyun Ju; Kim, Mee Kum; Wee, Won Ryang; Lee, Ryang Hwa; Fulcher, Samuel F; Oh, Joo Youn
To investigate the effect of an anti-inflammatory protein, TNF-α stimulated gene/protein (TSG)-6 and an antiapoptotic protein, stanniocalcin (STC)-1 on corneal endothelium in rabbits with transcorneal cryoinjury. Transcorneal freezing (-80°C) was applied to rabbit corneas for 30 seconds. Immediately post injury, either TSG-6 (10 μg/100 μL), STC-1 (10 μg/100 μL), or the same volume of balanced salt solution (BSS) was injected into the anterior chamber. Each eye was examined for corneal opacity, corneal thickness, endothelial cell density, and endothelial hexagonality every 2 to 6 hours for 48 hours post injury. The concentrations of myeloperoxidase (MPO) and IL-1β were measured in the aqueous humor every 6 hours. At 48 hours post injury, each cornea was assayed for TNF-α, IL-1β, IL-6, and MPO, and histologically evaluated with alizarin red-trypan blue staining, hematoxylin-eosin staining, and immunostaining for neutrophils. Tumor necrosis factor-α stimulated gene/protein-6 significantly decreased the development of corneal opacity and edema after cryoinjury compared with STC-1 or BSS. The corneal endothelial cell density and hexagonality were markedly preserved by TSG-6. The mRNA levels of TNF-α, IL-1β, and IL-6 in the cornea and the protein levels of MPO and IL-1β in the aqueous humor and cornea were significantly lower in TSG-6-treated eyes than BSS-treated controls. Similarly, the expression of fibroblast growth factor-2 was reduced by TSG-6 treatment. Histologic evaluation demonstrated that neutrophil infiltration of the cornea was decreased in TSG-6-treated eyes. Tumor necrosis factor-α stimulated gene/protein-6 protected corneal endothelial cells from transcorneal cryoinjury through suppression of inflammation. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.
Kim, Tae-im; Pak, Jhang Ho; Tchah, Hungwon; Lee, Seung-ah; Kook, Michael S
To evaluate the effect of various ceramides on the apoptosis of corneal fibroblasts and to determine the pathway on which they act. Corneal fibroblasts isolated and cultured from New Zealand white rabbits were exposed to various concentrations of ceramide types II and VI and phytoceramide types II and VI, and their apoptotic response was evaluated using an LDH assay and Hoechst and Annexin V staining. Corneal fibroblasts were preincubated with various concentrations of the CPP32-like protease inhibitor Z-VAD-FMK, the caspase-8 inhibitor IETD-CHO, and the caspase-9 inhibitor Z-LEHD-FMK before treatment with ceramide, and apoptotic response was assayed by LDH assay. In addition, cells treated with ceramide or phytoceramide were stained with an antibody to cytochrome c. At concentrations of 20 microM and higher, all 4 ceramides increased fibroblast apoptotic response significantly after 12 hours. Hoechst staining showed shrinkage of the cytoplasm, formation of apoptotic bodies, and nuclear fragmentation after ceramide exposure, and Annexin V staining showed small vesicles around the cell membrane. The CPP32-like protease inhibitor reduced the apoptotic response to all 4 ceramides. The specific caspase-8 inhibitor reduced the apoptotic response to ceramide type VI and phytoceramide types II and VI, whereas the specific caspase-9 inhibitor significantly reduced the apoptotic response to phytoceramide types II and VI. Following exposure to ceramides, corneal fibroblasts stained positively with antibody to cytochrome c. Ceramide induced apoptosis in cultured corneal fibroblasts. This apoptosis involved the caspase cascade and the mitochondrial pathway.
Zhang, Yan-qing; Zhang, Wen-jie; Liu, Wei; Hu, Xiao-jie; Zhou, Guang-dong; Cui, Lei; Cao, Yi-lin
To explore whether skin fibroblasts could be used as a cell source for reconstruction of the corneal stroma. It was an experimental study. Skin fibroblast cells were isolated from newborn rabbits, cultured and expanded in vitro. Cells were labeled with green fluorescence protein (GFP) gene by retro-viral infection. Fibroblasts at passage 3 were seeded on polyglycolic acid (PGA) non-woven fibers to form a cell-scaffold construct. Constructs were then implanted into the adult rabbit corneal stroma layer after being cultured in vitro for 1 week. Engineered stroma were observed continuously and harvested after 8 weeks of transplantation for gross, histological evaluation and Keratocan examination. PGA alone was used as control. The engineered tissue in the cornea became transparent gradually over a period of 8 weeks. Histological analysis showed that engineered stromal lamellar was relatively regular and the orientation of fibers was parallel to the surface of cornea, which is similar to normal cornea. The implanted cells were confirmed by GFP expression under fluorescent microscope, which also express Keratocan. By transmission electron microscopy examination, no significant difference in the diameter of collagen fiber was observed between engineered stroma (33.08 + or - 2.47) nm and normal stroma (t = 1.80, P = 0.0771). Skin fibroblast cells could be used as seed cells for reconstruction of the corneal stroma.
Gore, Daniel M; O'Brart, David; French, Paul; Dunsby, Chris; Allan, Bruce D
To measure depth-specific riboflavin concentrations in corneal stroma using two-photon fluorescence microscopy and compare commercially available transepithelial corneal collagen cross-linking (CXL) protocols. Transepithelial CXL riboflavin preparations--MedioCross TE, Ribocross TE, Paracel plus VibeX Xtra, and iontophoresis with Ricrolin+--were applied to the corneal surface of fresh postmortem rabbit eyes in accordance with manufacturers' recommendations for clinical use. Riboflavin 0.1% (VibeX Rapid) was applied after corneal epithelial debridement as a positive control. After riboflavin application, eyes were snap frozen in liquid nitrogen. Corneal cross sections 35-μm thick were cut on a cryostat, mounted on a slide, and imaged by two-photon fluorescence microscopy. Mean (SD) concentrations were calculated from five globes tested for each protocol. Peak riboflavin concentration of 0.09% (± 0.01) was observed within the most superficial stroma (stromal depth 0-10 μm) in positive controls (epithelium-off). At the same depth, peak stromal riboflavin concentrations for MedioCross TE, Ricrolin+, Paracel/Xtra, and Ribocross TE were 0.054% (± 0.01), 0.031% (0.003), 0.021% (± 0.001), and 0.015% (± 0.004), respectively. At a depth of 300 μm (within the demarcation zone commonly seen after corneal cross-linking), the stromal concentration in epithelium-off positive controls was 0.075% (± 0.006), while at the same depth MedioCross TE and Ricrolin+ achieved 0.018% (± 0.006) and 0.016% (0.002), respectively. None of the remaining transepithelial protocols achieved concentrations above 0.005% at this same 300-μm depth. Overall, MedioCross TE was the best-performing transepithelial formulation. Corneal epithelium is a significant barrier to riboflavin absorption into the stroma. Existing commercial transepithelial CXL protocols achieve relatively low riboflavin concentrations in the anterior corneal stroma when compared to gold standard epithelium-off absorption
Background Acacia honey is a natural product which has proven to have therapeutic effects on skin wound healing, but its potential healing effects in corneal wound healing have not been studied. This study aimed to explore the effects of Acacia honey (AH) on corneal keratocytes morphology, proliferative capacity, cell cycle, gene and protein analyses. Keratocytes from the corneal stroma of six New Zealand white rabbits were isolated and cultured until passage 1. The optimal dose of AH in the basal medium (FD) and medium containing serum (FDS) for keratocytes proliferation was identified using MTT assay. The morphological changes, gene and protein expressions of aldehyde dehydrogenase (ALDH), marker for quiescent keratocytes and vimentin, marker for fibroblasts were detected using q-RTPCR and immunocytochemistry respectively. Flowcytometry was performed to evaluate the cell cycle analysis of corneal keratocytes. Results Cultured keratocytes supplemented with AH showed no morphological changes compared to control. Keratocytes cultured in FD and FDS media supplemented with 0.025% AH showed optimal proliferative potential compared with FD and FDS media, respectively. Gene expressions of ADLH and vimentin were increased in keratocytes cultured with AH enriched media. All proteins were expressed in keratocytes cultured in all media in accordance to the gene expression findings. No chromosomal changes were detected in keratocytes in AH enriched media. Conclusion Corneal keratocytes cultured in media supplemented with 0.025% AH showed an increase in proliferative capacity while retaining their morphology, gene and protein expressions with normal cell cycle. The results of the present study show promising role of AH role in accelerating the initial stage of corneal wound healing. PMID:24885607
Ker-Woon, Choy; Abd Ghafar, Norzana; Hui, Chua Kien; Mohd Yusof, Yasmin Anum
Acacia honey is a natural product which has proven to have therapeutic effects on skin wound healing, but its potential healing effects in corneal wound healing have not been studied. This study aimed to explore the effects of Acacia honey (AH) on corneal keratocytes morphology, proliferative capacity, cell cycle, gene and protein analyses. Keratocytes from the corneal stroma of six New Zealand white rabbits were isolated and cultured until passage 1. The optimal dose of AH in the basal medium (FD) and medium containing serum (FDS) for keratocytes proliferation was identified using MTT assay. The morphological changes, gene and protein expressions of aldehyde dehydrogenase (ALDH), marker for quiescent keratocytes and vimentin, marker for fibroblasts were detected using q-RTPCR and immunocytochemistry respectively. Flowcytometry was performed to evaluate the cell cycle analysis of corneal keratocytes. Cultured keratocytes supplemented with AH showed no morphological changes compared to control. Keratocytes cultured in FD and FDS media supplemented with 0.025% AH showed optimal proliferative potential compared with FD and FDS media, respectively. Gene expressions of ADLH and vimentin were increased in keratocytes cultured with AH enriched media. All proteins were expressed in keratocytes cultured in all media in accordance to the gene expression findings. No chromosomal changes were detected in keratocytes in AH enriched media. Corneal keratocytes cultured in media supplemented with 0.025% AH showed an increase in proliferative capacity while retaining their morphology, gene and protein expressions with normal cell cycle. The results of the present study show promising role of AH role in accelerating the initial stage of corneal wound healing.
Lee, Hyun Soo; Chung, Sung Kun
To evaluate the effect of subconjunctival injection of suramin on corneal neovascularization in rabbits. Corneal neovascularization was induced by silk suturing of the corneal stroma in 40 eyes of 40 male New Zealand white rabbits. Five days after suture placement, all rabbits were randomly divided into 4 groups of 10 rabbits and were treated subconjunctivally with balanced salt solution 0.1 mL (group 1), suramin 0.1 mL (10 mg/mL and 100 mg/mL, groups 2 and 3, respectively), and bevacizumab 2.5 mg/0.1 mL (group 4). Digital photographs of eyes were obtained and analyzed on days 7, 14, and 28 after subconjunctival injections. In addition, vascular endothelial growth factor (VEGF) enzyme-linked immunosorbent assay (ELISA) and immunohistochemical analyses were used to estimate the level of VEGF and the expression of VEGF and basic FGF in neovascularized cornea, respectively. The neovascularized area in control was increased significantly for 14 days after subconjunctival injection, but slightly decreased on day 28. On days 7 and 14, group 4 exhibited greater antiangiogenic effect than group 3, but group 3 exhibited greater antiangiogenic effect than group 4 on day 28. VEGF ELISA analysis showed the mean concentration of VEGF in group 4 was significantly lower than with other treatments for the first 14 days, but the mean concentration of VEGF in group 4 was similar to that with group 3 on day 28. Immunohistochemical analysis showed that the expressions of both VEGF and basic fibroblast growth factor (FGF) were reduced in group 3 and that bevacizumab reduced VEGF expression relative to basic FGF on day 28. Subconjunctival suramin 100 mg/mL exhibited less antiangiogenic effect than bevacizumab 2.5 mg during the early period of treatment, but it had a longer effect than that of bevacizumab later. Therefore, the combination of subconjunctival bevacizumab and suramin may provide a more potent effect in early treatment as well as a longer antiangiogenic effect in
Abd Ghafar, Norzana; Chua, Kien Hui; Wan Ngah, Wan Zurinah; Che Hamzah, Jemaima; Othman, Fauziah; Abd Rahman, Ropilah; Hj Idrus, Ruszymah
The in vivo quiescent corneal stroma keratocytes need to be transformed to activated state in order to obtain sufficient number of cells either for monolayer evaluation or corneal stroma reconstruction. This study aimed to investigate the phenotypic characterization of corneal stromal cells during culture expansion from the limbal region of the cornea. Isolated corneal keratocytes from limbal tissue of New Zealand White Strain rabbits' corneas (n = 6) were culture expanded until three passages. Keratocytes morphology was examined daily with viability, growth rate, number of cell doubling and population doubling time were recorded at each passage. The expression of collagen type 1, aldehyde dehydrogenase (ALDH), lumican and alpha smooth muscle actin (α-SMA) were detected by RT-PCR. Immunocytochemistry was also used to detect ALDH, α-SMA, collagen type I and Cytokeratin-3 (CK3). Growth kinetic study revealed that the growth rate was low at the initial passage but increase to about two folds with concomitant reduction in population doubling time in later passages. Freshly isolated and cultured keratocytes expressed collagen type 1, ALDH and lumican but α-SMA expression was absent. However, α-SMA was expressed along with the other genes during culture expansion. Keratocytes at P1 expressed all the proteins except CK3. These results suggest that cultured keratocytes maintained most of the gene expression profile of native keratocytes while the emergence of α-SMA in serial passages showed a mix population of various phenotypes. The phenotypic characterization of monolayer keratocytes provides useful information before reconstruction of bioengineered tissue or in vitro pharmaceutical applications.
Amano, Shiro; Yokoo, Seiichi; Uchida, Saiko; Yamagami, Satoru; Usui, Tomohiko; Kimura, Yu; Tabata, Yasuhiko
Purpose To isolate fibroblast precursors from rabbit corneal stroma using a sphere-forming assay, to engineer corneal stroma with the precursors and gelatin, and to establish the therapeutic application of precursors in a rabbit corneal stroma. Methods In the in vitro study, a sphere-forming assay was performed to produce precursors from rabbit corneal stroma. Corneal stroma was engineered by cultivating precursors in porous gelatin for one week. In the in vivo study, the engineered corneal stromal sheet with precursors (precursor/gelatin group) or with fibroblasts (fibroblast /gelatin group) or without cells (gelatin group) was transplanted to a pocket of rabbit corneal stroma. Gene expression and extracellular matrix production were examined immunohistochemically in each group one week and four weeks after surgery. Results In the in vitro study, cells in the spheres were BrdU-positive, and their progeny were keratocan-positive. The study also showed that the corneas transplanted with a porous gelatin sheet did not show any opacity four weeks after transplantation in any group. In the gelatin sheet of the precursor/gelatin group, a more intense expression of type I collagen was observed relative to the other two groups four weeks after the surgery. Conclusions Our findings demonstrate that the transplantation of fibroblast precursors combined with gelatin hydrogel into the corneal stroma is a possible treatment strategy for corneal stromal regeneration. PMID:18852871
Mimura, Tatsuya; Amano, Shiro; Yokoo, Seiichi; Uchida, Saiko; Yamagami, Satoru; Usui, Tomohiko; Kimura, Yu; Tabata, Yasuhiko
To isolate fibroblast precursors from rabbit corneal stroma using a sphere-forming assay, to engineer corneal stroma with the precursors and gelatin, and to establish the therapeutic application of precursors in a rabbit corneal stroma. In the in vitro study, a sphere-forming assay was performed to produce precursors from rabbit corneal stroma. Corneal stroma was engineered by cultivating precursors in porous gelatin for one week. In the in vivo study, the engineered corneal stromal sheet with precursors (precursor/gelatin group) or with fibroblasts (fibroblast /gelatin group) or without cells (gelatin group) was transplanted to a pocket of rabbit corneal stroma. Gene expression and extracellular matrix production were examined immunohistochemically in each group one week and four weeks after surgery. In the in vitro study, cells in the spheres were BrdU-positive, and their progeny were keratocan-positive. The study also showed that the corneas transplanted with a porous gelatin sheet did not show any opacity four weeks after transplantation in any group. In the gelatin sheet of the precursor/gelatin group, a more intense expression of type I collagen was observed relative to the other two groups four weeks after the surgery. Our findings demonstrate that the transplantation of fibroblast precursors combined with gelatin hydrogel into the corneal stroma is a possible treatment strategy for corneal stromal regeneration.
Pang, Kunpeng; Du, Liqun; Zhang, Kai; Dai, Chenyang; Ju, Chengqun; Zhu, Jing; Wu, Xinyi
The aim of this study was to construct a rabbit anterior corneal replacement for transplantation using acellular porcine corneal matrix (APCM) and rabbit epithelial or stromal cells. APCM was prepared from fresh porcine cornea treated with 0.5% (wt./vol.) sodium dodecyl sulfate (SDS) solution. The expanded stromal cells were first injected into APCM parallel to its surface and were cultured in a shaking culture system for 7 days to obtain the stromal construct. Next, corneal epithelial cells were cultured on the stromal construct surface for another 7 days to obtain rabbit anterior corneal lamella. The construct had a phenotype similar to that of normal cornea, with high expression of cytokeratin 3 in the epithelial cell layer and vimentin in the stromal cells. More importantly, the construct integrated well with the implanted host corneal tissue, and the implant cornea maintained transparency in the 6-month follow-up, although there was a slight haze in the central corneal area. The endothelium in the surgery cornea had a similar cell density and mosaic pattern with normal cornea as shown by confocal laser corneal microscopy, and the regenerated corneal epithelial cells on the implant surface showed a similar morphology to that of natural epithelial cells. These results demonstrate that the constructed anterior corneal replacement exhibits an excellent biological property for lamellar keratoplasty and might be a possible alternative to human corneal tissue in the future. PMID:27930708
Tao, Xiangchen; Yu, Haiqun; Zhang, Yong; Li, Zhiwei; Jhanji, Vishal; Ni, Shouxiang; Wang, Ya; Mu, Guoying
To evaluate the role of corneal epithelium in riboflavin/ultraviolet-A (UVA) mediated corneal collagen cross-linking treatment. Fifty New Zealand rabbits were divided into 5 groups: UVA treatment with or without corneal epithelium, UVA+riboflavin treatment with or without corneal epithelium, and control without any treatment. All rabbits were sacrificed after irradiation and subsequently 4 mm × 10 mm corneal strips were harvested for biomechanical evaluation. UVA irradiation alone did not enhance the maximal stress and Young's modulus of corneal specimens with (3.15 ± 0.56 mpa, 1.00 ± 0.09 mpa) or without (3.53 ± 0.85 mpa, 0.94 ± 0.21 mpa) the corneal epithelium, compared to specimens in the control group (4.30 ± 0.68 mpa, 1.03 ± 0.24 mpa). However, UVA irradiation combined with riboflavin significantly increased the maximal stress and Young's modulus of corneal specimens with (5.27 ± 1.09 mpa, 1.23 ± 0.23 mpa, P < 0.05) or without (7.16 ± 1.88 mpa, 1.42 ± 0.16 mpa, P < 0.05) corneal epithelium when compared to the control group. The maximal stress and Young's modulus of cornea in UVA+riboflavin and "epithelium-off" group were 35.9% and 15.4% higher compared to the UVA+riboflavin and "epithelium-on" group, respectively (P < 0.05). Our study shows that UVA+riboflavin treatment significantly affects the biomechanical properties of the cornea with and without epithelial removal. However, corneas without epithelium seem to benefit more compared to corneas with the epithelium.
Hao, Zhao-Qin; Song, Jin-Xin; Pan, Shi-Yin; Zhang, Lin; Cheng, Yan; Liu, Xian-Ning; Wu, Jie; Xiao, Xiang-Hua; Gao, Wei; Zhu, Hai-Feng
AIM To observe the therapeutic effect of corneal collagen cross-linking (CXL) in combination with liposomal amphotericin B in fungal corneal ulcers. METHODS New Zealand rabbits were induced fungal corneal ulcers by scratching and randomly divided into 3 groups, i.e. control, treated with CXL, and combined therapy of CXL with 0.25% liposomal amphotericin B (n=5 each). The corneal lesions were documented with slit-lamp and confocal microscopy on 3, 7, 14, 21 and 28d after treatment. The corneas were examined with transmission electron microscopy (TEM) at 4wk. RESULTS A rabbit corneal ulcer model of Fusarium was successfully established. The corneal epithelium defect areas in the two treatment groups were smaller than that in the control group on 3, 7, 14 and 21d (P<0.05). The corneal epithelium defect areas of the combined group was smaller than that of the CXL group (P<0.05) on 7 and 14d, but there were no statistical differences on 3, 21 and 28d. The corneal epithelium defects of the two treatment groups have been healed by day 21. The corneal epithelium defects of the control group were healed on 28d. The diameters of the corneal collagen fiber bundles (42.960±7.383 nm in the CXL group and 37.040±4.160 nm in the combined group) were thicker than that of the control group (24.900±1.868 nm), but there was no difference between the two treatment groups. Some corneal collagen fiber bundles were distorted and with irregular arrangement, a large number of fibroblasts could be seen among them but no inflammatory cells in both treatment groups. CONCLUSION CXL combined with liposomal amphotericin B have beneficial effects on fungal corneal ulcers. The combined therapy could alleviate corneal inflammattions, accelerate corneal repair, and shorten the course of disease. PMID:27990355
Luengo Gimeno, Federico; Lavigne, Victoria; Gatto, Silvia; Croxatto, J Oscar; Correa, Laura; Gallo, Juan E
To evaluate the efficacy of autologous corneal epithelial sheet implantation in restoring transparency of rabbit corneas severely injured by alkaline and the effect of photocoagulation in arresting corneal neovessel ingrowth. Ophthalmology Department, School of Biomedical Sciences, Universidad Austral, Buenos Aires, Argentina. Limbal stem-cell deficiency (LSCD) was induced in 14 rabbits by alkali burns. A limbal cell biopsy was done in the contralateral eye, and the cells were cultured on a fibroblast feeder layer grown on autologous clotted platelet-poor plasma or commercial fibrin for 21 days. Anterior keratectomy was followed by suturing corneal cell sheets over the stroma. If regrowth of vessels occurred, argon laser photocoagulation was applied to them. Rabbits were killed at 30, 60, 90, 180, and 360 days and the corneas processed for histopathology and inmunohistochemistry. A small (2.5 mm(2)) limbal biopsy achieved stem-cell replication in vitro. Corneal clarity and epithelial defects evolved with a trend toward improvement. There was a significant reduction in corneal neovascularization. Histology showed a multilayered stratified epithelium including several epithelial-like cells with clear cytoplasm in the deepest part. There were no signs of intraepithelial mucin cells on the implanted corneas. Immunohistochemical results showed expression of cytokeratins 3 and 12 in the central corneal epithelium and an absence of cytokeratin 19. Autologous limbal epithelial cell transplantation improved the corneal surface in eyes with LSCD. Photocoagulation of neovessel ingrowth was effective over the 1-year follow-up. Results may facilitate the application of this technique in patients.
Li, Xinyu; Li, Zhongguo; Qiu, Liangxiu; Zhao, Changsong; Hu, Zhulin
In order to investigate the effect of nerve growth factor (NGF) on the proliferation of rabbit corneal endothelial cells and epithelial cells, the in vitro cultured rabbit corneal endothelial cells and epithelial cells were treated with different concentrations of NGF. MTT assay was used to examine the clonal growth and proliferation of the cells by determining the absorbency values at 570 nm. The results showed that NGF with three concentrations ranging from 5 U/mL to 500 U/mL enhanced the proliferation of rabbit corneal endothelial cells in a concentration-dependent manner. 50 U/mL and 500 U/mL NGF got more increase of proliferation than that of 5 U/mL NGF did. Meanwhile, 50 U/mL and 500 U/mL NGF could promote the proliferation of the rabbit corneal epithelial cells significantly in a concentration-dependent manner. However, 5 U/mL NGF did not enhance the proliferation of epithelial cells. It was suggested that exogenous NGF can stimulate the proliferation of both rabbit corneal endothelial and epithelial cells, but the extent of modulation is different.
ElKitkat, Rania S; Ebeid, Weam M; Habib, Eman K; Shoukry, Youssef
To investigate the safety of intracameral injection of minimum bactericidal concentration (MBC) of povidone iodine (PI) on the corneal endothelium in a rabbit model as a proposed method of prophylaxis against postoperative endophthalmitis. We included 32 New Zealand white rabbits in the study. Twenty-four rabbits received intracameral injections of 0.1 mL of 0.25% PI, and they were sequentially killed at intervals; first, seventh, and 14th day. The control group included 4 rabbits that received intracameral injections of 0.1 mL normal saline, and 4 rabbits that underwent the same intraocular procedure without injections (sham operated). Slit-lamp examination and ultrasonic corneal pachymetry were performed before and after injections for both eyes. The corneas were histopathologically examined by light and electron microscopy. MBC of PI (0.25%) was toxic to rabbits' corneal endothelium as evident by histopathological changes, corneal edema, and increased corneal thickness on day 1. Signs of healing were obvious on day 7 and were almost complete on day 14, as detected by histopathology, subsidence of corneal edema, and normalization of corneal thickness. MBC (0.25%) of PI was found toxic to the rabbits' corneal endothelium, with progressive regeneration and complete healing within 2 weeks. To our knowledge, we are the first to use MBC of PI in intracameral injection trials. Further studies on primates, which have more comparable regenerative capacity to humans' corneal endothelium, are encouraged to evaluate their endothelial healing response.
Kato, T.; Nakayasu, K.; Hosoda, Y.; Watanabe, Y.; Kanai, A.
AIMS—To investigate the histopathological changes of rabbit corneas after laser in situ keratomileusis (LASIK) and to evaluate the corneal wound healing process. METHODS—A LASIK was performed on white rabbit eyes. Postoperatively, rabbits were killed on days 1 and 7, and at 1, 3, and 9 months. RESULTS—Periodic acid Schiff (PAS) positive material and disorganised collagen fibre were seen along the interface of the corneal flap even 9 months after operation. CONCLUSIONS—The wound healing process still continued at 9 months after LASIK indicating that a much longer time than expected was required for corneal wound healing following LASIK. PMID:10535863
Darrell, R W; Modak, S M; Fox, C L
Norfloxacin is a new synthetic antibiotic with a broad spectrum of activity against gram-positive and gram-negative bacteria, and is more effective than the aminoglycosides against P aeruginosa. In this study norfloxacin was particularly effective in treatment of P aeruginosa infection of the rabbit cornea, and caused no toxicity in normal rabbit eyes after prolonged administration. The addition of silver to norfloxacin enhances its antipseudomonal activity, and broadens its spectrum to include antifungal activity. In this study, silver norfloxacin appears to be the most effective antibiotic against P aeruginosa corneal ulcer in the rabbit. Because of its broad antibacterial spectrum, silver norfloxacin may be useful in the initial treatment of bacterial corneal ulcer before the identity of the bacteria is known. Because of its low toxicity in topical administration, and its antifungal and antibacterial activity, silver norfloxacin may be helpful in prophylaxis against infection in chronic corneal ulcers. Images FIGURE 1 FIGURE 2 FIGURE 3 PMID:6242083
Abe, Kosuke; Hibino, Tsuyoshi; Mishima, Hiroshi; Shimomura, Yoshikazu
SPARC (osteonectin/BM40) is detected in the corneal stroma during the wound-healing process. To understand the metabolism of SPARC in the cornea, we investigated the effects of cytokines and growth factors on SPARC synthesis by rabbit corneal epithelial cells and fibroblasts. Rabbit corneal epithelial cells or fibroblasts were cultured for 3 days with serum-containing minimal essential medium (MEM), then subcultured for 3 days on serum-free MEM with epidermal growth factor (EGF), platelet-derived growth factor (PDGF), transforming growth factor-beta (TGF-beta), or interleukin-1beta (IL-1beta). SPARC concentration in the medium was measured by the ELISA method using anti-SPARC monoclonal antibody. The concentration of SPARC in the conditioned medium of the epithelial cells depended on either cell numbers or cultivation periods. When EGF was added to the medium, the amount of SPARC in the medium decreased. The addition of IL-1beta, PDGF, or TGF-beta did not affect SPARC synthesis by the epithelial cells. The production of SPARC by rabbit corneal fibroblasts was low compared with that by epithelial cells. However, the synthesis of SPARC by corneal fibroblasts was significantly enhanced by the addition of TGF-beta. The addition of IL-1beta, PDGF, or EGF slightly increased SPARC synthesis by corneal fibroblasts. Cytokines and growth factors modulate SPARC synthesis by rabbit corneal epithelial cells and fibroblasts. These results suggest that cytokines and growth factors modulate cell-matrix interaction in corneal wound healing, possibly by regulating SPARC synthesis.
Ashton, P; Wang, W; Lee, V H
The objective of this study was to determine which of the five or six corneal epithelial layers was rate-limiting in the corneal penetration and metabolism of levobunolol in the pigmented rabbit. Corneal penetration and metabolism were evaluated using the isolated cornea in the modified Ussing chamber. Levobunolol and its metabolite, dihydrolevobunolol, were assayed by reversed phase high-performance liquid chromatography using spectrophotometric detection. EDTA (0.1 and 0.5%) and benzalkonium chloride (0.005-0.05%) were used to disrupt the integrity of the corneal epithelial layers. EDTA, which loosened the tight junctions between the superficial corneal epithelial cells, reduced both the transcorneal flux and metabolism of levobunolol. In contrast, benzalkonium chloride, which disrupted the integrity of the outermost corneal epithelial layers, enhanced the transcorneal levobunolol flux while reducing its extent of metabolism. The extent of enhancement in transcorneal flux afforded by 0.025% benzalkonium chloride was comparable to that seen in the deepithelized cornea. Within 5 min of contact by the corneal epithelium with this preservative, the ratio of dihydrolevobunolol concentration on the endothelial to the epithelial side was reduced by two-thirds. Although direct confirmation is required, the above findings are consistent with the hypothesis that the rate-limiting layer to corneal penetration of levobunolol resides in the outermost two to three layers of the corneal epithelium, whereas the metabolic barrier resides in deeper lying regions.
Youm, Jie Hyun; Heo, Jeong-Hwa; Kim, Hyo Myung; Song, Jong-Suk
In Asian countries, laser iridotomy for the treatment of angle-closure glaucoma is a common cause of bullous keratopathy, which may be associated with a shallow anterior chamber and dark iris pigmentation in Asians. Several cases of corneal decompensation after argon laser iridotomy have been reported. In the present study, we evaluated the harmful effects of argon laser iridotomy on the corneal endothelium. Argon laser iridotomy was performed on the right eyes of pigmented rabbits. Changes in corneal thickness and endothelial cell density after laser iridotomy were evaluated. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was performed for assessment of corneal endothelial cell apoptosis. Combined staining with alizarin red and trypan blue, as well as a live/dead cell assay, were performed for evaluation of damage to the corneal endothelium induced by laser iridotomy. Corneal thickness did not change immediately after laser iridotomy; however, a significant increase was observed 24 hours after iridotomy (p = 0.001). The endothelial cell density of laser-treated eyes four days after laser iridotomy was significantly decreased compared with control eyes (p < 0.001). TUNEL staining showed many TUNEL-positive cells in the corneal endothelium and corneal stroma. No endothelial trypan blue-stained cell nuclei were observed after laser iridotomy; however, several large endothelial cells with damaged membrane integrity were observed. The live/dead cell assay clearly showed a large number of dead cells stained red in several areas throughout the entire corneal button 24 hours after iridotomy. Argon laser iridotomy induces corneal endothelial cell apoptosis in pigmented rabbit eyes, resulting in decreased endothelial cell density.
Posch, Leila C.; Zhu, Meifang; Robertson, Danielle M.
Purpose. To evaluate the effects of a chemically preserved multipurpose contact lens care solution (MPS) on the corneal epithelial surface and Pseudomonas aeruginosa (PA) internalization in the rabbit corneal epithelium. Methods. Rabbits were fit in one eye with a silicone hydrogel lens (balafilcon A) soaked overnight in a borate-buffered MPS (BioTrue). The contralateral eye was fit with a lens removed directly from the blister pack containing borate-buffered saline (control). Lenses were worn for 2 hours. Upon lens removal, corneas were challenged ex vivo with invasive PA strain 6487 and assessed for PA internalization. Ultrastructural changes were assessed using scanning electron (SEM) and transmission electron microscopy (TEM). Results. Scanning electron microscopy showed frank loss of surface epithelium in MPS-exposed eyes, while control eyes exhibited occasional loss of surface membranes but retention of intact junctional borders. Transmission electron microscopy data supported and extended SEM findings, demonstrating the presence of epithelial edema in MPS-treated eyes. There was a 12-fold increase in PA uptake into the corneal epithelium following wear of the MPS-treated lens compared to control (P = 0.008). Conclusions. These data demonstrate that corneal exposure to MPS during lens wear damages the surface epithelium and are consistent with our previous clinical data showing an increase in bacterial binding to exfoliated epithelial cells following MPS use with resultant increased risk for lens-mediated infection. These findings also demonstrate that the PA invasion assay may provide a highly sensitive quantitative metric for assessing the physiological impact of lens-solution biocompatibility on the corneal epithelium. PMID:24876286
Fischak, Corinna; Klaus, Robert; Werkmeister, René M.; Hohenadl, Christine; Prinz, Martin; Schmetterer, Leopold
Purpose The present study was performed to investigate the effect of topically administered chitosan-N-acetylcysteine (C-NAC) on corneal wound healing in a rabbit model. Methods A total of 20 New Zealand White rabbits were included in the randomized, masked, placebo-controlled experiment. A monocular epithelial debridement was induced by manual scraping under general anesthesia. Animals were randomized to receive either C-NAC two times daily or placebo. Monitoring of corneal wound healing was performed with ultra-high-resolution optical coherence tomography (OCT) and epithelial fluorescein staining. Measurements were done immediately after and up to 72 hours after wound induction. Results No difference in wound size was found immediately after surgical debridement between the C-NAC group and the placebo group. Wound healing was significantly faster in the C-NAC group compared to the placebo group (p < 0.01 for both methods). A good correlation was found between the OCT technique and the epithelial fluorescein staining in terms of wound size (r = 0.94). Conclusions Administration of C-NAC containing eye drops twice daily leads to a faster corneal wound healing in a rabbit model of corneal debridement as compared to placebo. Ultra-high-resolution OCT is considered a noninvasive, dye-free alternative to conventional fluorescein staining in assessing corneal wound healing also in humans. PMID:28695002
Tanaka, Yuji; Shi, Dong; Kubota, Akira; Takano, Yoshimasa; Fuse, Nobuo; Yamato, Masayuki; Okano, Teruo; Nishida, Kohji
Tissue engineering and transplantation of autogenic grafts have been widely investigated for solving problems on current allograft treatments (i.g., donor shortage and rejection). However, it is difficult to obtain an autogenic corneal stromal replacement that is composed of transparent, tough, and thick collagen constructs by current cell culture-based tissue engineering. Aim of this study is to develop transparent dermis for an autogenic corneal stroma transplantation. This study examined dehydration at 4-8°C and carbodiimide cross-linking on cloudy rabbit dermis (approx. 1.8%-3.8% light transmittance at 550 nm) for dermis optical clearing. Transparency of dehydrated rabbit dermis was founded to be approx. 37.9%-41.4% at 550 nm. Additional cross-linking treatment on dehydrated dermis prevented from swelling and clouding in saline, and improved its transparency to be 56.9% at 550 nm. Rabbit corneal epithelium was found to regenerate on optically cleared dermis in vitro. Furthermore, no abnormal biological response (i.e., inflammation, vascularization, and the barrier defect of epithelia) or no optical functional change on optically cleared dermis was observed during its 4-week autogenic transplantation into rabbit corneal stromal pocket.
Tani, Emiko; Katakami, Chikako; Negi, Akira
The effects of various eye drops on corneal wound healing, particularly in the subepithelial haze area, were investigated histologically following superficial keratectomy in rabbits. Mechanical superficial keratectomy was performed in rabbit eyes. Tranilast, betamethasone, hyaluronic acid, and diclofenac eye drops were administered after the procedure. Physiological saline was used as a control. Corneas were excised 1, 2, 3, and 4 weeks after keratectomy, labeled with 3H-thymidine or 3H-proline, and subjected to autoradiography. In the control and diclofenac groups, corneal haze occurred 3 weeks after keratectomy. Histological examination revealed an accumulation of proliferating keratocytes and active synthesis of collagen in the subepithelial area. In the tranilast and betamethasone groups, formation of corneal haze was reduced compared to the controls. The proliferation of keratocytes and the production of collagen in the corneal stroma were inhibited by these drugs. In the hyaluronic acid group also, corneal haze was decreased. In this group, although the proliferation of keratocytes was activated compared to the controls, abnormal accumulation of keratocytes in the subepithelial area was not detected. Tranilast and betamethasone decrease the formation of subepithelial haze by inhibiting keratocyte proliferation and synthesis of extracellular matrix in the corneal stroma. Hyaluronic acid, on the other hand, inhibits subepithelial haze by promoting physiologic wound healing.
Eshar, D; Wyre, N R; Schoster, J V
A four-year-old, 1·3-kg entire male Holland Lop pet rabbit (Oryctolagus cuniculus) was presented with a two-day history of bilateral epiphora and blepharospasm. Fluorescein staining revealed bilateral medio-ventral corneal ulceration. Initial topical treatment included ophthalmic broad-spectrum antibiotics and artificial tear solutions. Over a six-month period, antibiotics were changed based on corneal culture and sensitivity test results, and periodic corneal debridement was performed. With little to no improvement, and recurrence of the previous clinical signs, surgical intervention was considered but withheld because of individual pet consideration and owner's reluctance. Hydrophilic contact lenses were placed for corneal support but failed and caused a severe ocular response. Corneal collagen shields were placed bilaterally in order to promote corneal healing. Recheck examination performed seven days after placement revealed complete resolution of the ulcer in one eye and major reduction of the corneal ulcer in the contra-lateral eye. © 2011 British Small Animal Veterinary Association.
Zainal Abidin, Fadhilah; Hui, Chua Kien; Luan, Ng Sook; Mohd Ramli, Elvy Suhana; Hun, Lee Ting; Abd Ghafar, Norzana
There has been no effective treatment or agent that is available for corneal injury in promoting corneal wound healing. Previous studies on edible bird's nest extract (EBN) had reported the presence of hormone-like substance; avian epidermal growth factor that could stimulate cell division and enhance regeneration. This study aimed to investigate the effects of EBN on corneal keratocytes proliferative capacity and phenotypical changes. Corneal keratocytes from six New Zealand White Rabbits were isolated and cultured until Passage 1. The proliferative effects of EBN on corneal keratocytes were determined by MTT assay in serum-containing medium (FDS) and serum-free medium (FD). Keratocytes phenotypical changes were morphologically assessed and gene expression of aldehyde dehydrogenase (ALDH), collagen type 1 and lumican were determined through RT-PCR. The highest cell proliferation was observed when both media were supplemented with 0.05% and 0.1% EBN. Cell proliferation was also consistently higher in FDS compared to FD. Both phase contrast micrographs and gene expression analysis confirmed the corneal keratocytes retained their phenotypes with the addition of EBN. These results suggested that low concentration of EBN could synergistically induce cell proliferation, especially in serum-containing medium. This could be a novel breakthrough as both cell proliferation and functional maintenance are important during corneal wound healing. The in vitro test is considered as a crucial first step for nutri-pharmaceutical formation of EBN-based eye drops before in vivo application.
Marino, Gustavo K; Santhiago, Marcony R; Santhanam, Abirami; Lassance, Luciana; Thangavadivel, Shanmugapriya; Medeiros, Carla S; Bose, Karthikeyan; Tam, Kwai Ping; Wilson, Steven E
The purpose of this study was to investigate whether myofibroblast-related fibrosis (scarring) after microbial keratitis was modulated by the epithelial basement membrane (EBM) injury and regeneration. Rabbits were infected with Pseudomonas aeruginosa after epithelial scrape injury and the resultant severe keratitis was treated with topical tobramycin. Corneas were analyzed from one to four months after keratitis with slit lamp photos, immunohistochemistry for alpha-smooth muscle actin (α-SMA) and monocyte lineage marker CD11b, and transmission electron microscopy. At one month after keratitis, corneas had no detectible EBM lamina lucida or lamina densa, and the central stroma was packed with myofibroblasts that in some eyes extended to the posterior corneal surface with damage to Descemet's membrane and the endothelium. At one month, a nest of stromal cells in the midst of the SMA + myofibroblasts in the stroma that were CD11b+ may be fibrocyte precursors to myofibroblasts. At two to four months after keratitis, the EBM fully-regenerated and myofibroblasts disappeared from the anterior 60-90% of the stroma of all corneas, except for one four-month post-keratitis cornea where anterior myofibroblasts were still present in one localized pocket in the cornea. The organization of the stromal extracellular matrix also became less disorganized from two to four months after keratitis but remained abnormal compared to controls at the last time point. Myofibroblasts persisted in the posterior 10%-20% of posterior stroma even at four months after keratitis in the central cornea where Descemet's membrane and the endothelium were damaged. This study suggests that the EBM has a critical role in modulating myofibroblast development and fibrosis after keratitis-similar to the role of EBM in fibrosis after photorefractive keratectomy. Damage to EBM likely allows epithelium-derived transforming growth factor beta (TGFβ) to penetrate the stroma and drive development and
Cejka, Cestmír; Ardan, Taras; Sirc, Jakub; Michálek, Jiří; Beneš, Jiří; Brůnová, Blanka; Rosina, Jozef
Exposure of the cornea to UV radiation from sunlight evokes intraocular inflammation, photokeratitis. Photokeratitis is caused by UVB radiation. It is accompanied by changes of corneal hydration and light absorption. The aim of this study was to examine the effect of two UVB doses on corneal optics in rabbits and to compare these UVB doses with the equivalent exposure of UVB radiation reaching the human cornea from sunlight. Rabbit corneas were irradiated with a daily UVB dose of 0.25 J/cm(2) or 0.5 J/cm(2) for 4 days. One day after finishing the irradiations the rabbits were sacrificed and corneal light absorption measured using our spectrophotometrical method. Corneal hydration was examined using an ultrasonic Pachymeter every experimental day before the irradiation procedure and the last day before sacrificing the animals. Changes in corneal optics appeared after the repeated exposure of the cornea to a UVB dose of 0.25 J/ cm(2) and massively increased after the repeated exposure of the cornea to a UVB dose of 0.5 J/cm(2). The first significant changes in corneal hydration appeared after a single exposure of the cornea to a UVB dose of 0.25 J/cm(2). Changes in corneal hydration appeared after the exposure of the rabbit cornea to a single UVB dose equivalent to 2.6 hours of solar UVB radiation reaching the human cornea, as measured by UVB sensors embedded in the eyes of mannequin heads facing the sun on a beach at noon in July. Repeated exposure of the rabbit cornea to the same UVB dose evoked profound changes in corneal optics. Although comparison of experimental and outdoor conditions are only approximate, the results in rabbits point to the danger for the human eye from UVB radiation when short stays in sunlight are repeated for several consecutive days without UV protection.
A newly-developed macroscope was applied to observe the healing process of corneal epithelial wound in vivo. After removing epithelium of the central cornea, the changes of the corneal surface were observed with the macroscope and the findings were compared with histological examinations. At 12 hours after abrasion, areas unstained with Richardson's staining (R staining) appeared. In the histological section, a single layer of regenerating epithelial cells covered the same area. At 24 and 36 hours after abrasion, the epithelial defects became smaller but surrounding epithelium was rough and showed dot-like staining with R solution. By 2 days, the epithelial defects disappeared. On macroscopic observation, the central corneal surface showed a pavement-like appearance. Histology revealed that the regenerating epithelium still consisted of one or two layers. At 3 days, dot-like stainings were present only in the center and the corneal surface appeared considerably smooth. Histology also showed that regenerating epithelium became columnar and multilayered, thereby suggesting stratification. By 7 days, the abraded corneal surface had recovered its smooth appearance. Histologic sections also demonstrated that the epithelium had regained its normal structure. Thus, using this macroscope, findings suggesting the process of epithelial migration and proliferation could be observed.
Lee, You Kyung; Chung, Sung Kun
To evaluate the effect of thalidomide analogue CC-3052 on corneal neovascularization in the rabbit model. Corneal neovascularization was induced in 15 rabbits by a silk suture in the corneal stroma. At 1 week after suturing, 30 eyes were divided into 5 groups of 6 eyes each. Three groups were treated with topical CC-3052 at 3 different concentrations: 0.25% (group 1), 0.5% (group 2), and 1.0% (group 3). All treatments were performed twice a day for a week. A 0.5% concentration of CC-3052 was injected subconjunctivally once in group 4. In group 5, a topical balanced salt solution was added twice a day for a week as the experimental control group. Rabbit corneas were photographed by a digital camera and examined by the operating microscope. Half of the corneal specimens were analyzed histopathologically, and the other half were used to measure the concentration of tumor necrosis factor α and vascular endothelial growth factor (VEGF) messenger RNA by reverse transcriptase-polymerase chain reaction. The neovascularized area was decreased in all treatment groups compared with the control group. There was a significant difference in the percentage and score of corneal neovascularization between the control and all treatment groups. Inflammation, fibroblast, neovascularization, and anti-VEGF antibody intensities were significantly lower in the control group. The concentration of VEGF and tumor necrosis factor α was significantly lower in the control group. There was no difference between the treatment groups. Topical and subconjunctival administration of thalidomide analogue CC-3052 was found to be effective for the inhibition of corneal neovascularization.
Clarke, Thomas F; Johnson, Thomas E; Burton, Margaret B; Ketzenberger, Bryan; Roach, William P
In the 40 yr since lasers were invented, they have become commonplace in military operations, and while their utility in this setting is undeniable, they also represent a potential hazard for those in contact with them. This threat must be recognized, information must be gathered to understand this injury potential, and the necessary measures must be taken to properly protect those who will work, train, and fight with these systems. The exact mechanisms of laser/tissue interaction at 1540 nm are not well understood. Previous studies and textbooks show remarkable disparity in reporting where 1540 nm laser energy is deposited and the quantity of energy required to cause tissue damage. Rabbit cornea is very similar histologically to that of humans with the exception that it lacks Bowman's membrane. This model has been recommended as a reasonable approximation by past researchers and avoids the use of valuable non-human, primate research animals. A rabbit model was used to demonstrate the ability of the 1540 nm laser to produce corneal injuries. Various energies were applied to find the threshold at which injury is consistently produced. Observations included the appearance of the injury in the rabbit cornea. All rabbits were between 5 and 6 kg. Corneal injury was consistent at energies above 56 J x cm(-2). Injuries involved the deeper corneal stroma rather than only the epithelial layer, thus raising concern for permanent visual disability in those affected. The gross appearance of these injuries was white opaque areas easily seen within the corneal stroma. Data shows conclusively that the 1540 nm laser causes significant corneal damage at reproducible energy levels. Further research is clearly necessary to advance our understanding of the role of Bowman's membrane, the healing properties of the injured cornea, and the epidemiology of laser injury.
Vázquez, Natalia; Chacón, Manuel; Rodríguez-Barrientos, Carlos A.; Merayo-Lloves, Jesús; Naveiras, Miguel; Baamonde, Begoña; Alfonso, Jose F.; Zambrano-Andazol, Iriana; Riestra, Ana C.; Meana, Álvaro
Corneal keratoplasty (penetrating or lamellar) using cadaveric human tissue, is nowadays the main treatment for corneal endotelial dysfunctions. However, there is a worldwide shortage of donor corneas available for transplantation and about 53% of the world’s population have no access to corneal transplantation. Generating a complete cornea by tissue engineering is still a tough goal, but an endothelial lamellar graft might be an easier task. In this study, we developed a tissue engineered corneal endothelium by culturing human corneal endothelial cells on a human purified type I collagen membrane. Human corneal endothelial cells were cultured from corneal rims after corneal penetrating keratoplasty and type I collagen was isolated from remnant cancellous bone chips. Isolated type I collagen was analyzed by western blot, liquid chromatography -mass spectrometry and quantified using the exponentially modified protein abundance index. Later on, collagen solution was casted at room temperature obtaining an optically transparent and mechanically manageable membrane that supports the growth of human and rabbit corneal endothelial cells which expressed characteristic markers of corneal endothelium: zonula ocluddens-1 and Na+/K+ ATPase. To evaluate the therapeutic efficiency of our artificial endothelial grafts, human purified type I collagen membranes cultured with rabbit corneal endothelial cells were transplanted in New Zealand white rabbits that were kept under a minimal immunosuppression regimen. Transplanted corneas maintained transparency for as long as 6 weeks without obvious edema or immune rejection and maintaining the same endothelial markers that in a healthy cornea. In conclusion, it is possible to develop an artificial human corneal endothelial graft using remnant tissues that are not employed in transplant procedures. This artificial endothelial graft can restore the integrality of corneal endothelium in an experimental model of endothelial dysfunction
Énzsöly, Anna; Markó, Katalin; Tábi, Tamás; Szökő, Éva; Zelkó, Romána; Tóth, Miklós; Petrash, J Mark; Mátyus, Péter; Németh, János
The aim of this study is to determine the efficacy of a potent and specific vascular adhesive protein-1/semicarbazide-sensitive amine oxidase (VAP-1/SSAO) inhibitor, LJP 1207, as a potential antiangiogenic and anti-inflammatory agent in the therapy of corneal neovascularization. Corneal neovascularization was induced with intrastromal suturing in rabbits (n = 20). Topical treatment with VAP-1/SSAO inhibitor LJP 1207 (n = 5, 4 times a day), bevacizumab (n = 5, daily), their combination (n = 5) and vehicle only (n = 5, 4 times a day) were applied postoperatively for 2 weeks. The development and extent of corneal neovascularization were evaluated by digital image analysis. At the end of the observation period, the level of corneal and serum VAP-1/SSAO activity was measured fluorometrically and radiochemically. The corneal VAP-1/SSAO activity was significantly elevated in the suture-challenged vehicle-treated group (3,075 ± 1,009 pmol/mg/h) as compared to unoperated controls (464.2 ± 135 pmol/mg/h, p < 0.001). Treatment with LJP 1207 resulted in slower early phase neovascularization compared to vehicle-treated animals (not significant). At days 7-14, there was no significant difference in the extent of corneal neovascularization between inhibitor- and vehicle-treated corneas, even though inhibitor treatment caused a normalization of corneal VAP-1/SSAO activity (885 ± 452 pmol/mg/h). Our results demonstrate that the significant elevation of VAP-1/SSAO activity due to corneal injury can be prevented with VAP-1/SSAO inhibitor LJP 1207 treatment. However, normalization of VAP-1/SSAO activity in this model does not prevent the development of corneal neovascularization.
Marelli, Benedetto; Omenetto, Fiorenzo G.; Funderburgh, James L.; Kaplan, David L.
The worldwide need for human cornea equivalents continues to grow. Few clinical options are limited to allogenic and synthetic material replacements. We hypothesized that tissue engineered human cornea systems based on mechanically robust, patterned, porous, thin, optically clear silk protein films, in combination with human corneal stromal stem cells (hCSSCs), would generate 3D functional corneal stroma tissue equivalents, in comparison to previously developed 2D approaches. Silk film contact guidance was used to control the alignment and distribution of hCSSCs on RGD-treated single porous silk films, which were then stacked in an orthogonally, multi-layered architecture and cultured for 9 weeks. These systems were compared similar systems generated with human corneal fibroblasts (hCFs). Both cell types were viable and preferentially aligned along the biomaterial patterns for up to 9 weeks in culture. H&E histological sections showed that the systems seeded with the hCSSCs displayed ECM production throughout the entire thickness of the constructs. In addition, the ECM proteins tested positive for keratocyte-specific tissue markers, including keratan sulfate, lumican, and keratocan. The quantification of hCSSC gene expression of keratocyte-tissue markers, including keratocan, lumican, human aldehyde dehydrogenase 3A1 (ALDH3A1), prostaglandin D2 synthase (PTDGS), and pyruvate dehydrogenase kinase, isozyme 4 (PDK4), within the 3D tissue systems demonstrated upregulation when compared to 2D single silk films and to the systems generated with the hCFs. Furthermore, the production of ECM from the hCSSC seeded systems and subsequent remodeling of the initial matrix significantly improved cohesiveness and mechanical performance of the constructs, while maintaining transparency after 9 weeks. PMID:28099503
Chen, Wensheng; Li, Zhiyuan; Hu, Jiaoyue; Zhang, Zhenhao; Chen, Lelei; Chen, Yongxiong; Liu, Zuguo
Benzalkonium chloride (BAC) is the most common preservative in ophthalmic preparations. Here, we investigated the corneal alternations in rabbits following exposure to BAC. Twenty-four adult male New Zealand albino rabbits were randomly divided into three groups. BAC at 0.01%, 0.05%, or 0.1% was applied twice daily to one eye each of rabbits for 4 days. The contralateral untreated eyes were used as control. Aqueous tear production and fluorescein staining scores of BAC-treated eyes were compared with those of controls. The structure of the central cornea was examined by in vivo confocal microscopy. Expression of mucin-5 subtype AC (MUC5AC) in conjunctiva was detected by immunostainig on cryosections. Corneal barrier function was assessed in terms of permeability to carboxy fluorescein (CF). The distribution and expression of ZO-1, a known marker of tight junction, and reorganization of the perijunctional actomyosin ring (PAMR) were examined by immunofluorescence analysis. Although there were no significant differences between control and BAC-treated eyes in Schirmer scores, corneal fluorescein scores and the number of conjunctival MUC5AC staining cells, in vivo confocal microscopy revealed significant epithelial and stromal defects in all BAC-treated corneas. Moreover, BAC at 0.1% resulted in significant increases in central corneal thickness and endothelial CF permeability, compared with those in control eyes, and endothelial cell damage with dislocation of ZO-1 and disruption of PAMR. Topical application of BAC can quickly impair the whole cornea without occurrence of dry eye. A high concentration of BAC breaks down the barrier integrity of corneal endothelium, concomitant with the disruption of PAMR and remodeling of apical junctional complex in vivo. PMID:22022526
Wei, Shufang; Zhang, Cuiying; Zhang, Shaoru; Xu, Yanyun; Mu, Guoying
To study the treatment effect of corneal collagen cross-linking (CXL) combined with 440 nm blue light and riboflavin on bacterial corneal ulcer using animal experiments. A total of 21 New Zealand white rabbits that developed Staphylococcus aureus corneal ulcer were randomly divided into three groups. Seven rabbits were used as blank control groups; seven rabbits were treated with CXL combined with riboflavin and 440 nm blue light; and seven rabbits were treated with CXL combined with riboflavin and 370 nm ultraviolet A light. Necrotic tissues or secretions from the ulcer surface, eye secretions, conjunctival hyperemia, hypopyon, corneal infiltration, and pathological changes of the cornea were all observed. The 1st, 3th, and 7th day after CXL treatment, a statistically significant difference was found among the inflammation scores of the three groups. The scores of 440 and 370 groups decreased gradually, significantly lower than that of the control group. Bacterial cultures of 440 and 370 groups turned to be negative while that of the control group remained positive. After 1 day of CXL treatment, pathology pictures of the three groups all showed loss of corneal epithelia with many inflammatory cells in deep stroma. After 7 days of CXL treatment, abscess formed in almost all corneal area in the control group, while in 440 and 370 groups, multilayer healing of corneal epithelia, neovascularization, and many inflammatory cells within ulcers and proliferation of a small amount of fibroblast were seen. CXL combined with riboflavin and 440 nm blue light is effective in treating S. aureus corneal ulcer.
Li, Ying; Chen, Hui J; Zhang, Hua; Wu, Jian G; Hu, Yun T; Ma, Zhi Z
The aim of the study was to investigate wound healing and scar formation in rabbit corneal lamellar wounds repaired with simple interrupted sutures (SIS) or horizontal mattress sutures (HMS). Two parallel 'I'-shaped lamellar cornea wounds were created in one eye of 40 white New Zealand rabbits, while 5 uninjured rabbits were sacrificed to serve as normal controls. One side of the wounds, in the test rabbits, was closed with SIS, while the other side was treated with HMS. Ten days later, the stitches were removed under anesthesia. The animals were sacrificed on days 14 and 21, and months 3 and 6 after the suturing surgery, and corneal samples were subjected to histological and immunofluorescent studies: α-smooth muscle actin (α-SMA) and vimentin were used to detect myofibroblasts and fibroblasts, respectively, and collagen type I and III was used to detect extracellular matrix (ECM) deposition. Relevant mRNA levels were assessed by quantitative polymerase chain reaction (qPCR) to elucidate the differences in wound healing and formation of fibrosis. Macroscopic and hematoxylin and eosin staining observations showed that the two sides of the wounds developed the most prominent fibrotic tissue on day 21. The immunofluorescence and qPCR results showed that HMS wounds produced increased α-SMA, vimentin and collagen type III compared to the SIS wounds on day 14 or 21. The collagen type I expression showed no distinctive difference in SIS and HMS wounds. In conclusion, corneal lamellar wounds treated with SIS developed less fibrotic-related proteins and related mRNA in the early stages of wound healing than wounds treated with HMS. Although differences were not distinct after 3 months, the results of the present study suggest a benefit in choosing SIS over HMS, as at least the initial fibrotic process seems more benign with SIS. Corneal wounds should be carefully sutured, ensuring the tissue is well aligned.
Salomão, Marcella Q; Chaurasia, Shyam S; Sinha-Roy, Abhijit; Ambrósio, Renato; Esposito, Andrew; Sepulveda, Ricardo; Agrawal, Vandana; Wilson, Steven E
To investigate corneal wound healing following ultraviolet-A (UVA)/riboflavin corneal collagen cross-linking (CXL) in rabbit corneas. Thirty-six rabbits were enrolled in the study. Animals were divided into three treatment groups and corneas were analyzed at 24 hours and 4 weeks postoperatively. Thus, each group had 6 rabbits at each time point. Treatment groups were: 1) standard UVA+riboflavin CXL, 2) UVA alone, and 3) riboflavin alone. One eye of each rabbit served as an untreated control eye. TUNEL assay was performed to detect stromal cell apoptosis. Immunocytochemistry was performed to detect the inflammatory marker CD11b expressed in monocytes and the alpha-smooth muscle actin (SMA) marker expressed in myofibroblasts. At 24 hours, corneas from the UVA+riboflavin CXL group had significantly more apoptosis than the UVA alone and riboflavin alone groups. Eyes from all three groups had significantly more inflammatory cell influx into the cornea than unwounded controls. Four weeks after the procedure, many corneas in the UVA+riboflavin CXL group had mild haze, but very few SMA-positive myofibroblasts could be detected in the central cornea. Riboflavin+UVA CXL triggers more anterior keratocyte apoptosis than corneal scrape with UVA alone or riboflavin alone. Inflammation monitored by the monocyte marker CD11b was present, but not statistically different among the three groups. Very little myofibroblast generation could be detected after UVA+riboflavin CXL, indicating that the mild stromal haze associated with this procedure is normally related to transient corneal fibroblast generation rather than more persistent haze due to generation of myofibroblasts. Copyright 2011, SLACK Incorporated.
Yoshida, Junko; Heflin, Thomas; Zambrano, Andrea; Pan, Qing; Meng, Huan; Wang, Jiangxia; Stark, Walter J.; Daoud, Yassine J.
Purpose: Gamma irradiated corneas in which the donor keratocytes and endothelial cells are eliminated are effective as corneal lamellar and glaucoma patch grafts. In addition, gamma irradiation causes collagen cross inking, which stiffens collagen fibrils. This study evaluated gamma irradiated corneas for use in corneal transplantations in a rabbit model comparing graft clarity, corneal neovascularization, and edema. Methods: Penetrating keratoplasty was performed on rabbits using four types of corneal grafts: Fresh cornea with endothelium, gamma irradiated cornea, cryopreserved cornea, and fresh cornea without endothelium. Slit lamp examination was performed at postoperative week (POW) one, two, and four. Corneal clarity, edema, and vascularization were graded. Confocal microscopy and histopathological evaluation were performed. A P < 0.05 was statistically significant. Results: For all postoperative examinations, the corneal clarity and edema were statistically significantly better in eyes that received fresh cornea with endothelium compared to the other three groups (P < 0.05). At POW 1, gamma irradiated cornea scored better than the cryopreserved and fresh cornea without endothelium groups in clarity (0.9 vs. 1.5 and 2.6, respectively), and edema (0.6 vs. 0.8 and 2.0, respectively). The gamma irradiated corneas, cryopreserved corneas and the fresh corneas without endothelium, developed haze and edema after POW 2. Gamma irradiated cornea remained statistically significantly clearer than cryopreserved and fresh cornea without endothelium during the observation period (P < 0.05). Histopathology indicated an absence of keratocytes in gamma irradiated cornea. Conclusion: Gamma irradiated corneas remained clearer and thinner than the cryopreserved cornea and fresh cornea without endothelium. However, this outcome is transient. Gamma irradiated corneas are useful for lamellar and patch grafts, but cannot be used for penetrating keratoplasty. PMID:26180475
Yoshida, Junko; Heflin, Thomas; Zambrano, Andrea; Pan, Qing; Meng, Huan; Wang, Jiangxia; Stark, Walter J; Daoud, Yassine J
Gamma irradiated corneas in which the donor keratocytes and endothelial cells are eliminated are effective as corneal lamellar and glaucoma patch grafts. In addition, gamma irradiation causes collagen cross inking, which stiffens collagen fibrils. This study evaluated gamma irradiated corneas for use in corneal transplantations in a rabbit model comparing graft clarity, corneal neovascularization, and edema. Penetrating keratoplasty was performed on rabbits using four types of corneal grafts: Fresh cornea with endothelium, gamma irradiated cornea, cryopreserved cornea, and fresh cornea without endothelium. Slit lamp examination was performed at postoperative week (POW) one, two, and four. Corneal clarity, edema, and vascularization were graded. Confocal microscopy and histopathological evaluation were performed. A P < 0.05 was statistically significant. For all postoperative examinations, the corneal clarity and edema were statistically significantly better in eyes that received fresh cornea with endothelium compared to the other three groups (P < 0.05). At POW 1, gamma irradiated cornea scored better than the cryopreserved and fresh cornea without endothelium groups in clarity (0.9 vs. 1.5 and 2.6, respectively), and edema (0.6 vs. 0.8 and 2.0, respectively). The gamma irradiated corneas, cryopreserved corneas and the fresh corneas without endothelium, developed haze and edema after POW 2. Gamma irradiated cornea remained statistically significantly clearer than cryopreserved and fresh cornea without endothelium during the observation period (P < 0.05). Histopathology indicated an absence of keratocytes in gamma irradiated cornea. Gamma irradiated corneas remained clearer and thinner than the cryopreserved cornea and fresh cornea without endothelium. However, this outcome is transient. Gamma irradiated corneas are useful for lamellar and patch grafts, but cannot be used for penetrating keratoplasty.
Barbosa, Flávia Leão; Góes, Rejane Maira; de Faria-E-Sousa, Sidney Júlio; Haddad, Antonio
To investigate the proliferative behavior of the corneal and limbal epithelia after debridement on the central region of the rabbit cornea. After scraping a circular epithelial area, 5 mm in diameter, in the center of the cornea, () H-thymidine ( () H-TdR) was injected intravitreally, and the rabbits killed from 1 to 49 days afterward. The cornea, together with the adjacent conjunctiva, was processed for autoradiography. The regenerating epithelium at the center of the cornea exhibited high frequencies of labeled nuclei when compared to controls. The mitotic indexes for the limbus were comparable in experimental and control eyes. The unique basal stratum of the limbal epithelium exhibited quick proliferation and vertical migration in all eyes. Cells that remained labeled for four weeks or more were observed throughout the corneal epithelium, including its basal stratum, and this did not depend on epithelial damage. Corneal epithelium wounds are healed by sliding and proliferation of cells surrounding the epithelial gap without any evidence for the participation of the limbal epithelium. Daughter cells labeled with () H-TdR were visualized in all layers of the corneal epithelium up to 7 weeks after the DNA precursor injection. However, at this long interval, the only labeled cells in the limbus were in the suprabasal layers.
Kim, Tae-Hyun; Park, Young-Woo; Ahn, Jae-Sang; Ahn, Jeong-Taek; Kim, Se-Eun; Jeong, Man-Bok; Seo, Min-Su; Kang, Kyung-Sun
This study was performed to evaluate the effects of conditioned media (CM) from human amniotic epithelial cells (HAECs) on the corneal wound healing process. Eighteen rabbits (36 eyes) were used and randomly assigned to three groups according treatment: CM from HAECs (group 1), vehicle alone (group 2), and saline (group 3). Corneal alkali injuries were induced with 1 N sodium hydroxide. Each reagent used for treatment evaluation was injected into the dorsal bulbar subconjunctiva and the area of the corneal epithelial defect was measured every other day. Two animals from each group were euthanized at a time on days 3, 7, and 15, and the cornea was removed for histological examination. The sum of the epithelial defect areas measured on day 0 to day 6 as well as day 0 to day 14 in group 1 was significantly smaller than those of other groups. Histological examination revealed that the group 1 corneas had less inflammatory cell infiltration and showed more intact epithelial features compared to the other groups. These results suggest that CM from HAECs promote corneal wound healing in rabbits. PMID:23388445
Sharma, Ajay; Bettis, Daniel I.; Cowden, John W.
Purpose The renin angiotensin system (RAS) has been shown to modulate vascular endothelial growth factor and angiogenesis. In this study we investigated (i) the existence of the RAS components angiotensin converting enzyme (ACE) and angiotensin II receptors (AT1 and AT2) in the rabbit cornea using in vitro and ex vivo models and (ii) the effect of enalapril, an ACE inhibitor, to inhibit angiogenesis in rabbit cornea in vivo. Methods New Zealand White rabbits were used. Cultured corneal fibroblasts and corneal epithelial cells were used for RNA isolation and cDNA preparation using standard molecular biology techniques. PCR was performed to detect the presence of ACE, AT1, and AT2 gene expression. A corneal micropocket assay to implant a vascular endothelial growth factor (VEGF) pellet in the rabbit cornea was used to induce corneal angiogenesis. Rabbits of the control group received sterile water, and the treated group received 3 mg/kg enalapril intramuscularly once daily for 14 days starting from day 1 of pellet implantation. The clinical eye examination was performed by slit-lamp biomicroscopy. We monitored the level of corneal angiogenesis in live animals by stereomicroscopy at days 4, 9, and 14 after VEGF pellet implantation. Collagen type IV and lectin immunohistochemistry and fluorescent microscopy were used to measure corneal angiogenesis in tissue sections of control and enalapril-treated corneas of the rabbits. Image J software was used to quantify corneal angiogenesis in the rabbit eye in situ. Results Our data demonstrated the presence of ACE, AT1, and AT2 expression in corneal fibroblasts. Cells of corneal epithelium expressed AT1 and AT2 but did not show ACE expression. Slit-lamp examination did not show any significant difference between the degree of edema or cellular infiltration between the corneas of control and enalapril-treated rabbits. VEGF pellet implantation caused corneal angiogenesis in the eyes of vehicle-treated control rabbits, and the
Sharma, Ajay; Bettis, Daniel I; Cowden, John W; Mohan, Rajiv R
The renin angiotensin system (RAS) has been shown to modulate vascular endothelial growth factor and angiogenesis. In this study we investigated (i) the existence of the RAS components angiotensin converting enzyme (ACE) and angiotensin II receptors (AT(1) and AT(2)) in the rabbit cornea using in vitro and ex vivo models and (ii) the effect of enalapril, an ACE inhibitor, to inhibit angiogenesis in rabbit cornea in vivo. New Zealand White rabbits were used. Cultured corneal fibroblasts and corneal epithelial cells were used for RNA isolation and cDNA preparation using standard molecular biology techniques. PCR was performed to detect the presence of ACE, AT(1), and AT(2) gene expression. A corneal micropocket assay to implant a vascular endothelial growth factor (VEGF) pellet in the rabbit cornea was used to induce corneal angiogenesis. Rabbits of the control group received sterile water, and the treated group received 3 mg/kg enalapril intramuscularly once daily for 14 days starting from day 1 of pellet implantation. The clinical eye examination was performed by slit-lamp biomicroscopy. We monitored the level of corneal angiogenesis in live animals by stereomicroscopy at days 4, 9, and 14 after VEGF pellet implantation. Collagen type IV and lectin immunohistochemistry and fluorescent microscopy were used to measure corneal angiogenesis in tissue sections of control and enalapril-treated corneas of the rabbits. Image J software was used to quantify corneal angiogenesis in the rabbit eye in situ. Our data demonstrated the presence of ACE, AT(1), and AT(2) expression in corneal fibroblasts. Cells of corneal epithelium expressed AT(1) and AT(2) but did not show ACE expression. Slit-lamp examination did not show any significant difference between the degree of edema or cellular infiltration between the corneas of control and enalapril-treated rabbits. VEGF pellet implantation caused corneal angiogenesis in the eyes of vehicle-treated control rabbits, and the mean area
Kreger, A S; Gray, L D
Extracellular proteases of three cornea-virulent strains of Pseudomonas aeruginosa were isolated by sequential ammonium sulfate precipitation, Ultrogel AcA 54 gel filtration, and flat-bed isoelectric focusing. The purity of the preparations was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis , thin-layer isoelectric focusing in polyacrylamide gel, immunodiffusion and immunoelectrophoretic procedures, and tests for the presence of other known pseudomonal products. Light and electron microscopic examination of rabbit corneal lesions observed 4 to 6 h after the intracorneal injection of submicrogram amounts of the proteases revealed: (i) degeneration and necrosis of epithelium, endothelium, and keratocytes, (ii) infiltration, degeneration, and necrosis of polymorphonuclear leukocytes, (iii) loss of the characteristic weblike pattern, colloidal iron staining, and ruthenium red staining of the stromal proteoglycan ground substance, (iv) dispersal of strucutrally normal appearing collagen fibrils, ground substance, (iv) dispersal of structurally normal appearing collagen fibrils, and (v) accumulation of plasma proteins and fibrin in the necrotic corneas. These structural alterations are very similar to those observed previously during experimental P. aeruginosa keratitis, and this similarity supports the idea that pseudomonal proteases are responsible, at least in part, for the rapid and extensive liquefaction necrosis characteristic of pseudomonal-induced keratitis. In addition, the results support the idea that pseudomonal proteases elicit severe corneal damage by causing the loss of the corneal proteoglycan ground substance, thus resulting in dispersal of undamaged collagen fibrils, weakening of the corneal stroma, and subsequent descemetocele formation and corneal perforation by the anterior chamber pressure. Images PMID:415981
Topical treatment of corneal alkali burns with Gly-thymosin β4 solutions and in situ hydrogels via inhibiting corneal neovascularization and improving corneal epidermal recovery in experimental rabbits.
Zhang, Weili; Nie, Liya; Du, Lina; Chen, Wenyang; Wu, Zhihong; Jin, Yiguang
Corneal alkali burns are a severe disease and commonly encountered in the emergent clinic. A rapid medical treatment for the burn is very important. Gly-thymosin β4 (Gly-Tβ4) is a biomimic derivative of natural thymosin β4. The aim of this study is to evaluate the corneal recovery effects of Gly-Tβ4 topical therapy on alkali burns in rabbit corneas. Rabbit alkali burns were induced with NaOH-contained filter paper. Phosphate-buffered solutions at pH 7.0, Gly-Tβ4 solutions, blank in situ hydrogels, and Gly-Tβ4in situ hydrogels were dropped on the burned corneas. The treatments were continued for 14 days. Conjunctiva hyperemia, corneal edema, intraeye extravasation, hemorrhaging, corneal neovascularization (CNV), and corneal opacity were observed. Corneal immunohistochemistry and histopathology were performed. Gly-Tβ4 solutions led to a lower corneal burn index than the other regimens. Hydrogels may stimulate the burned corneas due to the direct contact of them, and prevent the rapid release of Gly-Tβ4. Gly-Tβ4 significantly inhibited CNV according to the images of the corneas, CNV areas, and CD31 expression. Furthermore, Gly-Tβ4 improved corneal epidermal recovery according to the histopathological result. Gly-Tβ4 solutions are a promising formulation for topical treatment of corneal alkali burns. Copyright © 2017 Elsevier Ltd and ISBI. All rights reserved.
Gouveia, Ricardo M; González-Andrades, Elena; Cardona, Juan C; González-Gallardo, Carmen; Ionescu, Ana M; Garzon, Ingrid; Alaminos, Miguel; González-Andrades, Miguel; Connon, Che J
Ideally, biomaterials designed to play specific physical and physiological roles in vivo should comprise components and microarchitectures analogous to those of the native tissues they intend to replace. For that, implantable biomaterials need to be carefully designed to have the correct structural and compositional properties, which consequently impart their bio-function. In this study, we showed that the control of such properties can be defined from the bottom-up, using smart surface templates to modulate the structure, composition, and bio-mechanics of human transplantable tissues. Using multi-functional peptide amphiphile-coated surfaces with different anisotropies, we were able to control the phenotype of corneal stromal cells and instruct them to fabricate self-lifting tissues that closely emulated the native stromal lamellae of the human cornea. The type and arrangement of the extracellular matrix comprising these corneal stromal Self-Lifting Analogous Tissue Equivalents (SLATEs) were then evaluated in detail, and was shown to correlate with tissue function. Specifically, SLATEs comprising aligned collagen fibrils were shown to be significantly thicker, denser, and more resistant to proteolytic degradation compared to SLATEs formed with randomly-oriented constituents. In addition, SLATEs were highly transparent while providing increased absorption to near-UV radiation. Importantly, corneal stromal SLATEs were capable of constituting tissues with a higher-order complexity, either by creating thicker tissues through stacking or by serving as substrate to support a fully-differentiated, stratified corneal epithelium. SLATEs were also deemed safe as implants in a rabbit corneal model, being capable of integrating with the surrounding host tissue without provoking inflammation, neo-vascularization, or any other signs of rejection after a 9-months follow-up. This work thus paves the way for the de novo bio-fabrication of easy-retrievable, scaffold-free human
Kobayashi, Toyoshige; Kan, Kazutoshi; Nishida, Kohji; Yamato, Masayuki; Okano, Teruo
We have performed clinical applications of cell sheet-based regenerative medicine with human patients in several fields. In order to achieve the mass production of transplantable cell sheets, we have developed automated cell culture systems. Here, we report an automated robotic system utilizing a cell culture vessel, cell cartridge. The cell cartridge had two rooms for epithelial cells and feeder layer cells separating by porous membrane on which a temperature-responsive polymer was covalently immobilized. After pouring cells into this robotic system, cell seeding, medium change, and microscopic examination during culture were automatically performed according to the computer program. Transplantable corneal epithelial cell sheets were successfully fabricated in cell cartridges with this robotic system. Then, fabricated cell sheets were transplanted onto ocular surfaces of rabbit limbal epithelial stem cell deficiency model after 6-h transportation using a portable homothermal container to keep inner temperature at 36 °C. Within one week after transplantation, normal corneal epithelium was successfully regenerated. This automatic cell culture system would be useful for industrialization of tissue-engineered products for regenerative medicine.
Zhang, Zhenhao; Chen, Lelei; Xie, Hui; Dong, Nuo; Chen, Yongxiong; Liu, Zuguo
Preservatives are a major component of the ophthalmic preparations in multi-dose bottles. The purpose of this study was to investigate the acute effect of benzalkonium chloride (BAC), a common preservative used in ophthalmic preparations, on the localization and expression of zonula occludens (ZO)-1 in the rabbit corneal epithelium in vivo. BAC at 0.005%, 0.01%, or 0.02% was topically applied to one eye each of albino rabbits at 5 min intervals for a total of 3 times. The contralateral untreated eyes served as controls. The following clinical indications were evaluated: Schirmer test, tear break-up time (BUT), fluorescein and rose Bengal staining. The structure of central cornea was examined by in vivo confocal microscopy, and the corneal barrier function was evaluated by measurement of corneal transepithelial electrical resistance and permeability to carboxy fluorescein. Whole mount corneas were analyzed by using fluorescence confocal microscopy for the presence of ZO-1, 2, occludin, claudin-1, Ki67 and cell apoptosis in the epithelium. The expression of ZO-1 in the corneal epithelium was also examined by western blot and reverse transcription-polymerase chain reaction analyses. Exposure to BAC resulted in higher rose Bengal staining scores while no significant changes in BUT, Schirmer and corneal florescein scores. It also induced corneal epithelial cell damage, dispersion of ZO-1 and ZO-2 from their normal locus at the superficial layer and disruption of epithelial barrier function. However, the amounts of ZO-1 mRNA and protein in the corneal epithelium were not affected by BAC treatment. Exposure to BAC can quickly impair the corneal epithelium without tear deficiency. BAC disrupts the tight junctions of corneal epithelium between superficial cells in the rabbit corneal epithelium in vivo. PMID:22815857
Chen, Wensheng; Hu, Jiaoyue; Zhang, Zhenhao; Chen, Lelei; Xie, Hui; Dong, Nuo; Chen, Yongxiong; Liu, Zuguo
Preservatives are a major component of the ophthalmic preparations in multi-dose bottles. The purpose of this study was to investigate the acute effect of benzalkonium chloride (BAC), a common preservative used in ophthalmic preparations, on the localization and expression of zonula occludens (ZO)-1 in the rabbit corneal epithelium in vivo. BAC at 0.005%, 0.01%, or 0.02% was topically applied to one eye each of albino rabbits at 5 min intervals for a total of 3 times. The contralateral untreated eyes served as controls. The following clinical indications were evaluated: Schirmer test, tear break-up time (BUT), fluorescein and rose Bengal staining. The structure of central cornea was examined by in vivo confocal microscopy, and the corneal barrier function was evaluated by measurement of corneal transepithelial electrical resistance and permeability to carboxy fluorescein. Whole mount corneas were analyzed by using fluorescence confocal microscopy for the presence of ZO-1, 2, occludin, claudin-1, Ki67 and cell apoptosis in the epithelium. The expression of ZO-1 in the corneal epithelium was also examined by western blot and reverse transcription-polymerase chain reaction analyses. Exposure to BAC resulted in higher rose Bengal staining scores while no significant changes in BUT, Schirmer and corneal florescein scores. It also induced corneal epithelial cell damage, dispersion of ZO-1 and ZO-2 from their normal locus at the superficial layer and disruption of epithelial barrier function. However, the amounts of ZO-1 mRNA and protein in the corneal epithelium were not affected by BAC treatment. Exposure to BAC can quickly impair the corneal epithelium without tear deficiency. BAC disrupts the tight junctions of corneal epithelium between superficial cells in the rabbit corneal epithelium in vivo.
Pot, Simon A.; Liliensiek, Sara J.; Myrna, Kathern E.; Bentley, Ellison; Jester, James V.; Nealey, Paul F.
Purpose. Keratocyte-to-myofibroblast differentiation is a key factor in corneal wound healing. The purpose of this study was to determine the influence of environmental nanoscale topography on keratocyte, fibroblast, and myofibroblast cell behavior Methods. Primary rabbit corneal keratocytes, fibroblasts, and myofibroblasts were seeded onto planar polyurethane surfaces with six patterned areas, composed of anisotropically ordered grooves and ridges with a 400-, 800-, 1200-, 1600-, 2000-, and 4000-nm pitch (pitch = groove + ridge width). After 24 hours cells were fixed, stained, imaged, and analyzed for cell shape and orientation. For migration studies, cells on each patterned surface were imaged every 10 minutes for 12 hours, and individual cell trajectories and migration rates were calculated Results. Keratocytes, fibroblasts, and myofibroblasts aligned and elongated to pitch sizes larger than 1000 nm. A lower limit to the topographic feature sizes that the cells responded to was identified for all three phenotypes, with a transition zone around the 800- to 1200-nm pitch size. Fibroblasts and myofibroblasts migrated parallel to surface ridges larger than 1000 nm but lacked directional guidance on submicron and nanoscale topographic features and on planar surfaces. Keratocytes remained essentially immobile Conclusions. Corneal stromal cells elongated, aligned, and migrated, differentially guided by substratum topographic features. All cell types failed to respond to topographic features approximating the dimensions of individual stromal fibers. These findings contribute to our understanding of corneal stromal cell biology in health and disease and their interaction with biomaterials and their native extracellular matrix. PMID:19875665
Koch, J M; Refojo, M F; Leong, F L
Elastofilcon A silcone rubber contact lenses induce less corneal swelling than no lens wear during sleep, and increasing the central thickness and volume of the lens does not influence its overnight performance. We sought to elucidate whether a silicone rubber lens can promote the distribution of atmospheric O2 on the cornea through a small interpalpebral opening under closed-eye conditions. Three groups of rabbit eyes comprised 12 eyes wearing Silflex (Dk 79.8 barrer) lenses, 12 with elastofilcon A (Dk 340 barrer) lenses, and 12 without lenses. All eyes were surgically closed overnight; six eyes in each group had a complete lid closure and six eyes had a partial tarsorrhaphy that left a small, central gap approximately 3 mm in length. When the lids were opened the next morning, the partially closed elastofilcon A eyes showed less corneal swelling (6.2 +/- 1.4%) than the partially closed no-lens eyes did (9.6 +/- 1.3%) (p less than 0.01), whereas the partially closed Silflex eyes were significantly more swollen (12.8 +/- 2.1%) (p = 0.01) than the other two partially closed groups were. The completely closed eyes showed no significant difference in corneal swelling among the groups. These results indicate that small lid gaps during sleep may lead to less corneal swelling when elastofilcon A lenses are used than with no lenses.
Pot, Simon A; Liliensiek, Sara J; Myrna, Kathern E; Bentley, Ellison; Jester, James V; Nealey, Paul F; Murphy, Christopher J
Keratocyte-to-myofibroblast differentiation is a key factor in corneal wound healing. The purpose of this study was to determine the influence of environmental nanoscale topography on keratocyte, fibroblast, and myofibroblast cell behavior. Primary rabbit corneal keratocytes, fibroblasts, and myofibroblasts were seeded onto planar polyurethane surfaces with six patterned areas, composed of anisotropically ordered grooves and ridges with a 400-, 800-, 1200-, 1600-, 2000-, and 4000-nm pitch (pitch = groove + ridge width). After 24 hours cells were fixed, stained, imaged, and analyzed for cell shape and orientation. For migration studies, cells on each patterned surface were imaged every 10 minutes for 12 hours, and individual cell trajectories and migration rates were calculated. Keratocytes, fibroblasts, and myofibroblasts aligned and elongated to pitch sizes larger than 1000 nm. A lower limit to the topographic feature sizes that the cells responded to was identified for all three phenotypes, with a transition zone around the 800- to 1200-nm pitch size. Fibroblasts and myofibroblasts migrated parallel to surface ridges larger than 1000 nm but lacked directional guidance on submicron and nanoscale topographic features and on planar surfaces. Keratocytes remained essentially immobile. Corneal stromal cells elongated, aligned, and migrated, differentially guided by substratum topographic features. All cell types failed to respond to topographic features approximating the dimensions of individual stromal fibers. These findings contribute to our understanding of corneal stromal cell biology in health and disease and their interaction with biomaterials and their native extracellular matrix.
Ohia, E; Kulkarni, P
Bovine cornea (epithelium and stroma) was transplanted on to the rabbit cornea from which the epithelium and stroma had been removed. Conjuntival hyperemia and edema occurred from day 1-5 post-operation, followed by neovascularization and graft rejection within 7-10 days. Topical dexamethasone (0.1%) and prenisolone (1%) t.i.d. inhibited post-surgical hyperemia, edema, delayed hypersensitivity and neovascularization. These agents and the immunosuppressants (cyclosporin A and rapamycin) inhibited graft rejection observed up to 20 days. After cessation of treatment on the 20th day, grafts remained viable up to 35 days with dexamethasone, 10 days with prednisolone and rapamycin, and 5 days with cyclosporin A.
Fukiage, Chiho; Nakajima, Takeshi; Takayama, Yoshiko; Minagawa, Yoko; Shearer, Thomas R; Azuma, Mitsuyoshi
To evaluate the ability of pituitary adenylate cyclase-activating polypeptide (PACAP) to induce growth of neuronal processes in cultured trigeminal ganglion cells, and to accelerate neurite outgrowth and recovery of corneal sensitivity after creation of a corneal flap in a rabbit model of laser-assisted in situ keratomileusis (LASIK) surgery. Animal study. The cDNA of rabbit PACAP was sequenced, and the expression of PACAP receptors in the trigeminal ganglia from rabbits was quantified by quantitative real-time polymerase chain reaction. Trigeminal ganglion cells were isolated from rabbits and cultured for 48 hours with or without PACAP27 (bioactive N-terminal peptide from PACAP). Cells were stained with antibody against neurofilaments, and neurite outgrowth was quantified by cell counting. In the rabbit LASIK model, a corneal flap with a planned thickness of 130 microm and 8.5 mm diameter was created with a microkeratome. The rabbits then received eyedrops containing PACAP27 four times a day for eight weeks, and corneal sensitivity was measured. Neurite outgrowth was assessed by staining histologic sections of the flap area for cholinesterase. The deduced amino acid sequence of PACAP in rabbit was identical to that of human. PACAP receptor, PAC1, was highly expressed in trigeminal ganglia from newborn and adult rabbits. PACAP27 at 1 microM induced growth of neuronal processes in cultured primary trigeminal ganglion cells. In the LASIK model, extensions of neuronal processes from amputated nerve trunks in cornea were observed after administration of eyedrops containing 1 or 10 microM PACAP27. The 10 microM PACAP27 treatment also greatly accelerated recovery of corneal sensitivity. PACAP may be a candidate drug for ameliorating dry eye after LASIK surgery.
Ichijima, H; Ohashi, J; Petroll, W M; Cavanagh, H D
We studied the effects of 24-hour wear of rigid gas permeable (RGP) contact lenses of varying oxygen transmissibilities on the rabbit cornea by measuring concomitant lactate dehydrogenase (LDH) activity in tears and by in vivo tandem scanning confocal microscopy (TSCM). We used a PMMA lens and rigid gas permeable (RGP) lenses that had Dk/L values ranging from 7 to 64 x 10(-9) (cm/sec) (mL O2/mL mmHg) and a uniform 0.15 mm thickness. After 6- and 24-hour contact lens wear, rabbit tear LDH activity increased according to the decrease in the Dk of RGP lenses. Tear LDH activity after 24 hours of lens wear was higher than after 6 hours. The observed increase in tear LDH activity was correlated with in vivo corneal epithelial morphology by tandem scanning confocal microscopy. The observed severity of desquamation and swelling of corneal epithelial cells was dependent upon the Dk/Ltotal of contact lenses worn, which directly related to the contact lens induced corneal hypoxia. Based on the results of this study, we conclude that: 1) a nap or accidental overnight wear of contact lenses with less than 20 x 10(-9) Dk/Ltotal could cause severe corneal epithelial damage; 2) the ultra high Dk lens appeared to alter the ocular surface least; and 3) TSCM accompanied with tear LDH assay is an objective, non-invasive in vivo method to assess the effect of contact lens wear on the ocular surface over time at the cellular level.
Mikesell, G W
Air Force laser safety standards are developed from laser-exposure data obtained in studies using experimental animals and from biomathematical modeling procedures. Interpretation of research data and predictive modeling calculations are enhanced by knowledge of the temperature values of the tissue absorption sites. Corneal temperature values for the normal, the anesthetized, and the laser-injured Dutch belted rabbit are presented and compared with values obtained in other studies. The corneal temperatures were measured by infrared radiometry.
Eurell, Thomas E.; Johnson, Thomas E.; Roach, William P.
In vitro exposures of explant rabbit corneas to single pulse 1540 nm infrared laser light operating at a pulse width of 0.8 milliseconds resulted in coagulative necrosis of both the corneal epithelium and stroma. Histomorphometric data correlated with increasing tissue radiant exposures. Histologic alterations in the corneal stroma were typical of matrix remodeling within the beam path and reactive to antibodies against matrix metalloproteinase-2. A two-dimensional electrophoretic analysis, using a mini-gel format, was developed to determine if specific corneal protein changes within tissue sections could be detected. Frozen sections taken through the center of the laser lesion were evaluated for proteomic data using tissue isoelectric focusing in the first dimension and polyacrylamide gel electrophoresis in the second dimension. Histomorphometric data describing the extent of the laser lesions were compared to the isoelectric points, molecular weights and relative densities of individual corneal proteins. Increasing radiant exposures of corneal tissues were associated with characteristic histomorphometric and proteomic changes.
Gan, Lisha; Fagerholm, Per; Palmblad, Jan
To study the expression of basic fibroblast growth factor (bFGF) in the early phases of corneal wound healing in the presence or absence of granulocytes. A central penetrating corneal alkali wound was inflicted to one eye in each of 14 rabbits under general anaesthesia. Subsequently, seven of the rabbits were given fucoidin i.v. for 36 hours in order to block the selectins on the vascular endothelium, thus preventing blood granulocytes from entering the tissues. Then, corneas were prepared, stained for bFGF and evaluated by light microscopy. Whereas normal corneal epithelium expressed bFGF weakly, conjunctival epithelium did so strongly, particularly the goblet cells. The corneal endothelium showed medium staining, while keratocytes and vascular endothelial cells did not consistently express bFGF. After 36 hours of wound healing, a marked up-regulation of bFGF expression was observed in the corneal epithelial and endothelial cells, as well as in the keratocytes, that were migrating into the wound. No other changes were noted. None of these features were modulated when granulocyte emigration was prevented by fucoidin administration. The difference in bFGF expression between the corneal and conjunctival epithelium suggests a role for this growth factor in the barrier function at the limbus. Moreover, the specific presence of bFGF in cells migrating into the wound indicates the participation of bFGF in corneal wound healing. Expression of bFGF was independent of granulocytes.
Shi, Wei-yun; Liu, Ting; Xie, Li-xin; Wang, Shen-guo
To study the effects of a biodegradable FK506 drug delivery system (DDS) on the inhibition of corneal rejection, to measure the concentration of FK506 in the aqueous humor and to study the relationship between intraocular concentration of FK506 and its immunosuppressive effects on corneal rejection. Corneal neo-vascularization was induced by 5 - 0 silk sutures in 68 New Zealand rabbits to establish a high risk corneal transplantation model. A unilateral 7 mm diameter central penetrating corneal transplantation was performed with 7.5 mm diameter grafts from health New Zealand rabbit donors. Grafted rabbits were randomized into five groups as follows: Group A: untreated control animals; Group B: DDS anterior chamber recipients without drug; Group C: 1 mg cyclosporine DDS anterior chamber recipients; Group D: 0.1% FK506-olive oil drop recipients; Group E: 0.5 mg FK506 DDS anterior chamber recipients. Grafts were examined with a slit lamp every other day and clinical conditions were scored for up to 28 weeks. The aqueous humor and cornea of Group D and Group E were collected, and the concentration of FK506 was determined. The expression of cytokines IL-2R alpha, MCP-1, Fas and FasL mRNA was detected with in situ hybridization method. The median survival time was (17.9 +/- 4.7) d in Group A (untreated corneal allograft), (20.0 +/- 3.7) d in Group B, (56.3 +/- 8.8) d in Group C, (78.1 +/- 7.2) d in Group D, and over 180 d in Group E. Statistically significant difference (F = 926.37, P = 0.0000) in the survival time of allograft has been found between Group E and other groups. The concentration of FK506 in aqueous humor was (15.7 +/- 2.6) ng/ml in Group E at one week and remained stable for at least 24 weeks, much higher than that in Group D (<0.3 ng/ml). The concentration of FK506 in cornea was also higher in Group E than that in Group D. The expression of cytokines IL-2R alpha and MCP-1 mRNA was detected, but the expression of Fas and FasL mRNA was not detected in Group
Yamada, M; Mashima, Y
Changes in the mitotic rate and epithelial keratin expression of corneal epithelial basal cells following corneal abrasion (7.0 mm in diameter) in rabbits were studied immunohistochemically using antiproliferating cell nuclear antigen (PCNA) monoclonal antibody and anti-epithelial keratin 1 (AE1). In the non-wounded control, the mitotic rate (PCNA positive cells in the basal cell layer) was approximately 4%, and only the superficial cells were stained by AE1 monoclonal antibody. One day after wounding, migrating epithelial cells at the leading edge, which reacted to AE1, showed low mitotic activity. At days 3 and 7, the mitotic rates of basal cells of regenerating epithelium were 3 times higher than that of controls. These basal cells displayed intensive staining with AE1, while the epithelium over the unwounded cornea exhibited a normal pattern limited to superficial cells. By 14 days after injury, the mitotic rate returned to normal and all epithelial cells expressed a normal AE1 staining pattern. Theses results suggest that regeneration of corneal epithelial basal cells involves changes in keratin expression, which might correlate with changes in the mitotic rate.
Mao, Xiaochun; Zhang, Shaowei; Hen, Hui; Du, Longting; Li, Guigang; Li, Bin; Zhang, Hong
This study examined the corneal permeability of topical eye drop solutions added with various corneal penetrating accelerators and gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA) by nuclear magnetic resonance imaging (MRI). Twenty-four New Zealand rabbits were randomly divided into 3 groups according to the random digits table: Gd-DTPA group, in which the rabbits received 23.45% Gd-DTPA; hyaluronic acid group, in which 23.45% Gd-DTPA plus 0.2% hyaluronic acid was administered; azone group, in which 23.45% Gd-DTPA with 0.2% azone was given. Fifty microliters of the eye drops was instilled into the conjunctive sac every 5 min, for a total of 6 applications in each group. Contrast medium signals in the cornea, anterior chamber, posterior chamber, and vitreous body were scanned successively by MRI. The morphology and cell density of the corneal endothelium were examined before and 24 h after the treatment. The results showed that the residence time of Gd-DTPA in the conjunctival sac in the hyaluronic acid and azone groups was longer than that in the Gd-DTPA group. The signals in the anterior chamber of the Gd-DTPA and hyaluronic acid groups were increased slightly, and those in the azone group strengthened sharply. The signal intensity continuously rose over 80 min before reaching plateau. The strengthening rate of signals in the anterior chamber was 19.63% in the Gd-DTPA group, 53.42% in the sodium hyaluronate group, and 226.94% in the azone group. No signal was detected in the posterior chamber or vitreous body in all the 3 groups. Corneal morphology and cell density did not show any significant changes after the treatment in all the 3 groups. It was concluded that azone can significantly improve the corneal permeability of drugs that are similar to Gd-DTPA in molecular weight and molecular size, and MRI is a noninvasive technique that can dynamically detect eye drop metabolism in real time.
Karla, Pradeep K; Pal, Dananjay; Mitra, Ashim K
Multidrug resistance associated protein (MRP) is a major family of efflux transporters involved in drug efflux leading to drug resistance. The objective of this study was to explore physical barriers for ocular drug absorption and to verify if the role of efflux transporters. MRP-2 is a major homologue of MRP family and found to express on the apical side of cell membrane. Cultured Rabbit Corneal Epithelial Cells (rCEC) were selected as an in vitro model for corneal epithelium. [14C]-erythromycin which is a proven substrate for MRP-2 was selected as a model drug for functional expression studies. MK-571, a known specific and potent inhibitor for MRP-2 was added to inhibit MRP mediated efflux. Membrane fraction of rCEC was used for western blot analysis. Polarized transport of [14C]-erythromycin was observed in rCEC and transport from B-->A was significantly high than from A-->B. Permeability's increased significantly from A-->B in the presence of MK-571 and ketoconozole. Uptake of [14C]-erythromycin in the presence of MK-571 was significantly higher than control in rCEC. RT-PCR analysis indicated a unique and distinct band at approximately 498 bp corresponding to MRP-2 in rCEC and MDCK11-MRP-2 cells. Immunoprecipitation followed by Western Blot analysis indicated a specific band at approximately 190 kDa in membrane fraction of rCEC and MDCK11-MRP-2 cells. For the first time we have demonstrated high expression of MRP-2 in rabbit corneal epithelium and its functional activity causing drug efflux. RT-PCR, immunoprecipitation followed by Western blot analysis further confirms the result.
Park, Jin-Heung; Joo, Choun-Ki; Chung, Sung Kun
To compare the antiangiogenic effects of tacrolimus and bevacizumab on corneal neovascularization (CNV) in rabbits. Neovascularization was induced in 32 eyes of 16 rabbits by placing a suture in the corneal stroma. Seven days after suture placement, all rabbits were divided into 4 groups and were treated subconjunctivally with bevacizumab (AVA_sub) 0.05 mL (5 mg/0.05 mL), tacrolimus (TAC_sub) 0.05 mL (0.25 mg/0.05 mL), balanced salt solution (0.05 mL was subconjunctivally injected in 1 eye of each rabbit and applied by eye drops in the other eyes, control group), and tacrolimus eye drops (TAC_drop) (5 mg/5 mL applied 4 times daily). Digital photographs were obtained and surface area of CNV was measured 7 days after subconjunctival injections. Corneal specimens were analyzed histopathologically and were used to measure the concentration of vascular endothelial growth factor (VEGF), tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), interleukin-1 beta (IL-1β), and monocyte chemoattractant protein 1 mRNA by reverse transcription polymerase chain reaction. In digital photographs, the neovascularized area was decreased in all treatment groups (AVA_sub, 0.58; TAC_sub, 0.60; TAC_drop, 0.68) compared with the control group (balanced salt solution, 0.81). Histological examination showed markedly regressed new vessels in treatment groups, and immunohistochemical staining revealed weakly stained anti-VEGF and anti-F4/80 antibodies in treatment groups. In semiquantitative reverse transcription polymerase chain reaction, concentration of VEGF (AVA_sub, 0.24; TAC_drop, 0.18), TNF-α (AVA_sub, 0.19; TAC_sub, 0.24; TAC_drop 0.15), and IL-1β (AVA_sub, 0.19; TAC_sub, 0.33; TAC_drop, 0.18) mRNA were significantly lower in treatment groups than in the control group (VEGF, 0.47; TNF-α, 0.44; IL-1β, 0.87) (P < 0.05). Topical and subconjunctival tacrolimus application may be useful in reducing CNV and have comparable effects to subconjunctival bevacizumab injection.
Kwon, Junki; Heo, Jeong Hwa; Kim, Hyo Myung
Purpose To evaluate and compare the toxic effects of eyedrops containing a fixed combination of 2.0% dorzolamide and 0.5% maleate timolol with or without preservatives on rabbit corneal endothelium. Methods This study was performed with 22 eyes of New Zealand white rabbits. Dorzolamide/timolol eyedrops with preservative (Cosopt group) or without preservative (Cosopt-S group) were diluted with a balanced salt solution at a 1 : 1 ratio. We injected 0.1 mL of diluted Cosopt into the anterior chamber of left eyes and an equal volume of diluted Cosopt-S into the anterior chamber of right eyes. Corneal thickness, corneal haze, and conjunctival injection were measured before and 24 hours after treatment. Endothelial damage was compared between both eyes by vital staining (alizarin red/trypan blue staining), live/dead cell assay, TUNEL assay, and scanning electron microscopy. Results Corneal endothelial damage was severe in the Cosopt group. Cosopt-treated eyes exhibited remarkable corneal edema and prominent apoptosis of endothelial cells. In addition, the live/dead cell assay revealed many dead cells in the endothelium, and scanning electron microscopy analysis showed that corneal endothelial cells exhibited a partial loss of microvilli on the surface as well as extensive destruction of intercellular junctions. However, in the Cosopt-S group, corneal edema was mild and the damage to the corneal endothelium was minimal. Conclusions The main cause of corneal endothelial toxicity was due to the preservative in the dorzolamide/timolol fixed combination eyedrops, and not the active ingredient. Thus, it appears to be safer to use preservative-free eyedrops during the early postoperative period. PMID:26457041
Cassagne, Myriam; Laurent, Camille; Rodrigues, Magda; Galinier, Anne; Spoerl, Eberhard; Galiacy, Stéphane D; Soler, Vincent; Fournié, Pierre; Malecaze, François
We compared an iontophoresis riboflavin delivery technique for transepithelial corneal collagen crosslinking (I-CXL) with a conventional CXL (C-CXL). We designed three experimental sets using 152 New Zealand rabbits to study riboflavin application by iontophoresis using charged riboflavin solution (Ricrolin+) with a 1-mA current for 5 minutes. The first set was to compare riboflavin concentration measured by HPLC in corneas after iontophoresis or conventional riboflavin application. The second set was to analyze autofluorescence and stromal collagen modification immediately and 14 days after I-CXL or C-CXL, by using nonlinear two-photon microscopy (TP) and second harmonic generation (SHG). In the third set, physical modifications after I-CXL and C-CXL were evaluated by stress-strain measurements and by studying corneal resistance against collagenase digestion. Based on HPLC analysis, we found that iontophoresis allowed riboflavin diffusion with 2-fold less riboflavin concentration than conventional application (936.2 ± 312.5 and 1708 ± 908.3 ng/mL, respectively, P < 0.05). Corneal TP and SHG imaging revealed that I-CXL and C-CXL resulted in a comparable increased anterior and median stromal autofluorescence and collagen packing. The stress at 10% strain showed a similar stiffness of corneas treated by I-CXL or C-CXL (631.9 ± 241.5 and 680.3 ± 216.4 kPa, respectively, P = 0.908). Moreover, we observed an increased resistance against corneal collagenase digestion after I-CXL and C-CXL (61.90% ± 5.28% and 72.21% ± 4.32% of remaining surface, respectively, P = 0.154). This experimental study suggests that I-CXL is a promising alternative methodology for riboflavin delivery in crosslinking treatments, preserving the epithelium.
Maurer, J K; Parker, R D; Petroll, W M; Carr, G J; Cavanagh, H D; Jester, J V
We have hypothesized that differences in ocular irritancy are related to differences in extent of initial injury and that, regardless of the processes leading to tissue damage, extent of injury is the primary factor that determines the final outcome of ocular irritation. In previous in vivo confocal microscopic (CM) studies we identified quantifiable differences in the extent of corneal injury occurring with four surfactants (three anionic, one cationic) known to cause different levels of ocular irritation and demonstrated that extent of initial corneal injury was related to the magnitude of cell death. The purpose of this study was to assess the applicability of this hypothesis to a broad sampling of surfactants. Specifically, initial corneal changes induced by seven different surfactants (one anionic, three cationic, three nonionic) were measured by in vivo CM and cell death was measured by an ex vivo live/dead assay. The right eye of each rabbit was treated by placing 10 microl of a surfactant directly on the cornea. Eyes were examined macroscopically and scored for irritation at 3 h and 1 day. At 3 h and 1 day, in vivo CM was used to examine the corneas and quantitate epithelial cell size, epithelial thickness, corneal thickness, and depth of stromal injury. At 3 h and/or at 1 day, corneas were removed and excised regions were placed in culture media containing 2 microM calcein AM and 4 microM ethidium homodimer. Using laser scanning CM, the number of dead epithelial and/or stromal cells in a 300 x 300 x 170-microm3 (xyz) volume of the cornea was determined. In vivo CM and live/dead assay findings revealed three surfactants to affect only the epithelium, three surfactants to affect the epithelium and superficial stroma, and one surfactant to affect the epithelium and deep stroma. Extent of initial corneal injury reflected level of ocular irritation, and magnitude of cell death was related to the extent of initial corneal injury. These findings are consistent
Bucak, Yasin Yücel; Erdurmus, Mesut; Terzi, Elçin Hakan; Kükner, Aysel; Çelebi, Serdal
We aimed to study the inhibitory effects of topical cyclosporine A (CsA) 0.05% on immune-mediated corneal neovascularization, and to compare its efficacy with those of dexamethasone 0.1% and bevacizumab 0.5%. Immune-mediated corneal neovascularization was created in 36 right eyes of 36 rabbits. The rabbits were then randomized into four groups. Group I received CsA 0.05%, Group II received dexamethasone 0.1%, Group III received bevacizumab 0.5%, and Group IV received isotonic saline twice a day for 14 days. The corneal surface covered with neovascular vessels was measured on the photographs. The rabbits were then sacrificed and the corneas excised. Paraffin-embedded sections were stained with hematoxylin-eosin and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay. The means of percent area of corneal neovascularization in Group I, II, III, and IV were 24.4%, 5.9%, 37.1%, and 44.1%, respectively. The inhibitory effect of CsA 0.05% was found to be better than the effect found in the bevacizumab 0.5% and control groups (p = 0.03 and p = 0.02, respectively). CsA 0.05% was found to have significantly lesser inhibitory effects on corneal neovascularization than dexamethasone 0.1% (p < 0.001). Apoptotic cell density was higher in Group III and Group IV than in Group I and Group II. There was no difference between Group I and Group II in terms of apoptotic cell density (p = 0.7). Topical CsA 0.05% was shown to have an inhibitory effect on immune-mediated corneal neovascularization in rabbits.
Toshida, Hiroshi; Tabuchi, Nobuhito; Koike, Daisuke; Koide, Misao; Sugiyama, Keikichi; Nakayasu, Kiyoo; Kanai, Atsushi; Murakami, Akira
A role of vitamin A in the synthesis of hyaluronic acid by skin cells is well known. Hyaluronic acid is produced by corneal epithelial cells and keratocytes in the eye. We investigated whether rabbit corneal epithelial cells and keratocytes release hyaluronic acid after exposure to vitamin A compounds. Rabbit corneal epithelial cells and keratocytes were inoculated with RCGM2 medium and incubated at 37ºC under 5% CO(2) in air for 24 h. The medium was then replaced with medium containing 0.1, 1, 10, or 100 μM retinoic acid or retinol palmitate (VApal) and incubated for another 48 h. Hyaluronic acid release from both corneal epithelial cells and keratocytes during culture was increased by retinoic acid at the lower concentration of 0.1 μM and 1 μM determined with a sandwich binding protein assay kit. However, it was significantly decreased at the higher concentrations of 10 μM and 100 μM, and the cell count determined with a Neutral Red assay kit was also decreased at these concentrations. On the other hand, hyaluronic acid release from corneal epithelial cells during culture was increased by VApal at the lower concentration of 0.1 μM and 1 μM, but there was no significant difference in the cell count for either corneal epithelial cells or keratocytes in the presence of VApal at any concentration. In conclusion, it is suggested that vitamin A stimulates the release of hyaluronic acid from cultured rabbit corneal epithelial cells and keratocytes.
Dutescu, R Michael; Panfil, Claudia; Schrage, Norbert
Ingredients of lubricant eye drops are potentially harmful to the ocular surface. The products Optive, Optive Fusion, Neopt were tested regarding corneal irritability versus Vismed Multi and 0.01% benzalkonium chloride as negative and positive control, respectively. Formulas (30-40μl per hour) were applied hourly in-vitro for six days on rabbit corneas (n=5, per product) cultured in artificial anterior chambers (EVEIT system). Initially, four corneal abrasions (2.4-4.6mm(2)) were induced. All defects were monitored during drop application by fluorescein stains and photographs. To ensure corneal vitality, glucose and lactate concentrations in artificial anterior chamber fluids were determined photometrically. All products showed a complete corneal healing on day 2. Thereafter, all five Optive-treated corneas developed progressive fluorescein-positive epithelial lesions until day six (24.96μm, ±21.45μm, p<0.01). For Optive Fusion three corneas showed corneal erosions on day six (23.11μm, ±37.02μm, p>0.5) while Vismed Multi did not adversely affect the corneal integrity. Glucose/lactate concentrations remained unchanged while lubricants were applied. Histology revealed epithelial loss and severe alterations of the superficial stroma for Optive. Optive Fusion displayed a comparable pathology. Neopt did not significantly affect the corneal healing and integrity. This study suggested a cumulative corneal toxicity of Optive and, to a lesser extent, Optive Fusion most likely caused by its oxidative preservative, SOC. Clinical data are needed to clarify the application frequency at which corneal toxicity might occur. Neopt and Vismed Multi did not affect the corneal integrity. Copyright © 2016 Elsevier GmbH. All rights reserved.
Wang, Peng; Sheng, Minjie; Li, Bing; Jiang, Yaping; Chen, Yihui
Tear high osmotic pressure (HOP) has been recognized as the core mechanism underlying ocular surface inflammation, injury and symptoms and is closely associated with many ocular surface diseases, especially dry eye. The endoplasmic reticulum (ER) is a multi-functional organelle responsible for protein synthesis, folding and transport, biological synthesis of lipids, vesicle transport and intracellular calcium storage. Accumulation of unfolded proteins and imbalance of calcium ion in the ER would induce ER stress and protective unfolded protein response (UPR). Many studies have demonstrated that ER stress can induce cell apoptosis. However, the association between tear HOP and ER stress has not been studied systematically. In the present study, rabbit corneal epithelial cells were treated with HOP and results showed that the production of reactive oxygen species increased markedly, which further activated the ER signaling pathway and ultimately induced cell apoptosis. These findings shed new lights on the pathogenesis and clinical treatment of dry eye and other ocular surface diseases. PMID:27158374
Bao, FangJun; Deng, ManLi; Wang, QinMei; Huang, JinHai; Yang, Jing; Whitford, Charles; Geraghty, Brendan; Yu, Ayong; Elsheikh, Ahmed
The relationship of corneal biomechanical metrics provided by the Ocular Response Analyzer (ORA) and Corvis ST (CVS) with physical intraocular pressure (IOPp) and central corneal thickness (CCT) was evaluated. Thirty fresh enucleated eyes of 30 rabbits were used in ex vivo whole globe inflation experiments. IOPp was measured with a pressure transducer and increased from 7.5 to 37.5 mmHg in steps of 7.5 mmHg while biomechanical data was acquired using the ORA and CVS. At least 3 examinations were performed at each pressure level, where CCT and twelve biomechanical metrics were recorded and analyzed as a function of IOPp. The biomechanical metrics included corneal hysteresis (CH) and corneal resistance factor (CRF), obtained by the ORA. They also included the applanation times (A1T, A2T), lengths (A1L, A2L) and velocities (A1V, A2V), in addition to the highest concavity time (HCT), peak distance (PD), radius (HR) and deformation amplitude (DA), obtained by the CVS. The variation of CCT and the twelve biomechanical metrics for the 30 rabbit eyes tested across the 5 pressure stages considered (inter-pressure differences) were statistically significant (P = 0.00). IOPp was highly to moderately correlated with most biomechanical metrics, especially CRF, A1T, A1V, A2V, PD and DA, while the relationships with CH, A2T, A1L and HCT were poor. IOP has important influences on most corneal biomechanical metrics provided by CVS and ORA. Two biomechanical metrics A1V and HR were influenced by CCT after correcting for the effect of IOP in most pressure stages, while the correlation with others were weak. Comparisons of research groups based on ORA and CVS with different IOPs and CCTs may lead to possible misinterpretations if both or one of which are not considered in the analysis.
Matsuda, Sanae; Hisama, Masayoshi; Shibayama, Hiroharu; Itou, Norihiko; Iwaki, Masahiro
The rabbit corneal epithelium model (RCE model) was developed as a three-dimensional in vitro model to replace animal testing for the assessment of eye tolerance. In the model, a stratified culture of rabbit corneal epithelial cells is grown at the air-liquid interface on an amniotic membrane acting as a parabasal membrane. The alkaline exposure was restored each day in the presence of no irritants, although with the addition of SLS, which is a major irritant, the restoration of deficit was inhibited on the RCE model in a dose-dependent manner. The results of this test were comparable with those of the Draize test, and thus, this method using the RCE model may prove to be a useful and sensitive in vitro eye irritation test. The lauryl fatty chain derivatives, such as polyoxyethylene (9) lauryl ether (PLE), sodium polyoxyethylene (2) lauryl ether sulfate (SPLE), mono glyceryl laurate (MGL), and sodium N-lauroyl-l-glutaminate (SLG), which are widely used as surfactants for toiletry products and cosmetics, were evaluated for in vitro eye irritation potential using the RCE model. SLS, PLE, SPLE, MGL, and SLG inhibited 88.7%, 59.2%, 69.0%, 47.5%, and 15.7% of the restoration of deletion 24h after treatment at a concentration of 0.05%. The IC(50) (50% inhibitory concentration) values of SLS, PLE, SPLE, MGL, and SLG were 0.002%, 0.021%, 0.005%, 0.056%, and 0.448%, respectively. These results indicated that a functional group at the end of lauryl chain is an important factor for inhibiting the restoration of deletion using the RCE model.
Twa, Michael D.; Li, Jiasong; Manapuram, Ravi K.; Menodiado, Floredes M.; Singh, Manmohan; Aglyamov, Salavat; Emelianov, Stanislav; Larin, Kirill V.
Structural properties of the cornea determine the shape and optical quality of the eye. Keratoconus, a structural degeneration of the cornea, is often treated with UV-induced collagen cross-linking to increase tissue resistance to further deformation and degeneration. Optimal treatments would be customized to the individual and consider preexisting structural properties as well as the effects induced by treatment and this requires the capability to noninvasively measure tissue properties. The purpose of this study is to use novel methods of optical elastography to study the effects of UV-induced corneal collagen cross-linking in the rabbit eye. Low-amplitude (<1μm) elastic flexural waves were generated using focused air-pulse stimulation. Elastic wave propagation was measured over a 10x10mm area using Phase Stabilized Swept Source Optical Coherence Elastography (PhS-SSOCE) with a sensitivity of ~ 10 nm. Wave amplitude and velocity were computed and compared in tissues before and after UV cross-linking. Wave amplitude was decreased by the cross-linking treatment, while wave velocity was greater in cross-linked tissue than it was in the untreated cornea. Decreased wave amplitude and increased wave velocity after cross-linking is consistent with increased tissue stiffness. This was confirmed by conventional mechanical tension testing. These results demonstrate that the combination of the PhS-SSOCE and focused air pulse stimulation is capable of measuring low amplitude tissue motion and quantifying corneal stiffness.
Wang, Ming X.; Gray, Trevor; Prabhasawat, Pinnita; Ma, Xiong; Culbertson, William; Forster, Richard; Hanna, Khalil; Tseng, Scheffer C. G.
We conducted a study to determine if preserved human amniotic membrane can reduce corneal haze induced by excimer laser photoablation. Excimer photoablation was performed bilaterally on 40 New Zealand white rabbits with a 6 mm ablation zone and 120 micrometer depth (PTK) using the VISX Star. One eye was randomly covered with a preserved human amniotic membrane and secured using four interrupted 10 - 0 nylon sutures; the other eye served as control. The amniotic membranes were removed at one week, and the corneal haze was graded with a slit-lamp biomicroscopy by three masked corneal specialists (WC, KH and RF) biweekly for the ensuing 12 weeks. Histology and in situ TUNEL staining (for fragmented DNA as an index for apoptosis) was performed at days 1, 3 and 7 and at 12 weeks. One week after excimer photoablation, the amniotic membrane-covered corneas showed more anterior stromal edema, which resolved at the second week. A consistent grading of organized reticular corneal haze was noted among the three masked observers. Such corneal haze peaked at the seventh week in both groups. The amniotic membrane-covered group showed statistically significant less corneal haze (0.50 plus or minus 0.15) than the control groups (1.25 plus or minus 0.35) (p less than 0.001). The amniotic membrane-covered corneas had less inflammatory response at days 1 and 3, showing nearly nil DNA fragmentation on keratocytes on the ablated anterior stromal and less stromal fibroblast activation. There is less altered epithelial cell morphology and less epithelial hyperplasia at 1 week in these amniotic membrane-treated eyes. We concluded from this study that amniotic membrane matrix is effective in reducing corneal haze induced by excimer photoablation in rabbits and may have clinical applications.
Liu, Lin; Li, Yong-Ping; Huang, Shu-Qi; Lin, Jian-Xian; Zhang, Wen-Xin
To evaluate the curative effect of KGF-2 on the alkali-injured rabbit eye and to investigate the mechanism of KGF-2 accelerating corneal epithelial wound healing. Alkali burn was produced in 24 corneas from 24 New Zealand rabbits. Four groups were randomly divided. Three groups (A, B, and C groups) were treated with KGF-2 solution (1, 50, 100 microg/ml, respectively), and one group (D group) was treated with phosphate-buffered saline (PBS) solution. The injured eyes were photographed after the fluorescence staining with a slit lamp and the pictures were analyzed with computer-aided picture analysis system to calculate the rate of corneal epithelial healing. Morphologic and immunohistological examinations (using P63, AE5 and EGFR antibodies) of the cornea were performed. KGF-2 at dosages ranging from 1 microg/ml to 100 microg/ml could enhance the cornea wound healing process. After 24 hours, epithelial healing rate of the 100 microg/ml KGF-2 group and the PBS treated group was 74% and 40%, respectively (P < 0.05). The corneal epithelial healing rate of each group was variable after four days and achieved complete healing after ten days. The P63 positive cells in KGF-2 groups appeared not only in the limbal area but also in the central area. For example, on the seventh day, in the limbal area, the P63 positive cells in the 100 microg/ml KGF-2 group, the PBS treated group and the normal group were 53.8 +/- 2.6, 29.5 +/- 2.2 and 17.0 +/- 2.1, respectively (P = 0.000). At the same time, the P63 positive cells in the non-limbal area in the 100 microg/ml KGF-2 group, the PBS treated group and the normal group were 69.5 +/- 2.8, 19.5 +/- 2.8 and 0, respectively (P = 0.000). These results suggested KGF-2 can stimulate the limbal epithelial stem cells to migrate to the central cornea. KGF-2 can accelerate the healing of alkali burned cornea.
Reichl, S; Bednarz, J; Müller-Goymann, C C
Aims: For the study of transcorneal in vitro permeation of ophthalmic drugs, excised animal cornea or corneal epithelial cell culture are frequently used as a replacement for the human cornea. The main purposes of this study were to reconstruct a complete human organotypic cornea equivalent, consisting of all three different cell types (epithelial, stromal, and endothelial); to test the barrier function of this bio-engineered human cornea using three different model drugs (pilocarpine hydrochloride (PHCl), befunolol hydrochloride (BHCl), and hydrocortisone (HC)); and to determine its usefulness as an in vitro model for prediction of ocular drug absorption into the human eye. Methods: A multilayer tissue construct was created step by step in Transwell cell culture insert using SV-40 immortalised human endothelial and epithelial cells and native stromal cells (fibroblasts). Morphology was characterised by light microscopy using routine H&E staining. Scanning electron microscopy was used to evaluate ultrastructural features. Ocular permeation of drugs across the human cornea construct was tested using modified Franz cells and compared with data obtained from excised porcine cornea and previously described porcine cornea constructs. Results and conclusion: The cornea construct exhibited typical corneal structures such as a monolayer of hexagonally shaped endothelial cells and a multilayered epithelium consisting of seven to nine cell layers with flat superficial cells. The formation of microplicae and microvilli was also confirmed. The human cornea construct showed similar permeation behaviour for all substances compared with excised porcine cornea. However, permeability (permeation coefficients Kp) of the human cornea equivalent (PHCl 13.4•10−6 (SD 3.01•10−6); BHCl 9.88•10−6 (SD 1.79•10−6); HC 5.41•10−6 (SD 0.40•10−6) cm/s) was about 1.6–1.8 fold higher than excised porcine cornea. Compared with data from the porcine cornea construct the
Nagano, Takashi; Hao, Ji-Long; Nakamura, Masatsugu; Nishida, Teruo
To understand the mechanism of corneal ulceration by characterizing the intracellular signaling pathways that regulate collagen degradation by corneal fibroblasts cultured in three-dimensional type I collagen gels. Specifically, the potential roles of protein kinase C (PKC) and protein kinase A (PKA) in collagen degradation were investigated. Rabbit corneal fibroblasts were cultured in three-dimensional type I collagen gels for 24 hours in the presence of plasminogen and in the absence or presence of activators or inhibitors of PKC or PKA. Degradation of collagen fibrils was then evaluated by measurement of released hydroxyproline, and the production of matrix metalloproteinases (MMPs) was assessed by gelatin zymography and immunoblot analysis. The PKC activator phorbol 12-myristate 13-acetate (PMA) increased the extent of collagen degradation by corneal fibroblasts in a dose-dependent manner, with the maximal effect apparent at a concentration of 0.1 microM. The inactive analog 4alpha-PMA had no effect on collagen degradation. The PKC inhibitor H-7 reduced the extent of collagen degradation by corneal fibroblasts in the absence or presence of PMA. Phorbol 12-myristate 13-acetate also increased the production of proMMP-1, -3, and -9 by corneal fibroblasts, whereas H-7 inhibited this effect. Neither the PKA activators 8-bromo-cAMP, isobutylmethylxanthine, and forskolin nor the PKA inhibitor HA1004 affected collagen degradation by corneal fibroblasts. These results demonstrate that PKC plays an important role in collagen degradation by corneal fibroblasts in three-dimensional type I collagen gels, whereas PKA does not appear to participate in this process.
Zheng, Guang-ying; Hao, Li-li; Wang, Rui-na; Lian, Yuan-jun; Tan, Nan
To investigate the influence of TGF-β2 antisense oligonucleotide (ASON) on preventing corneal scar hyperplasia in rabbits and to provide experimental evidence for its clinical application. It was an experimental study. One hundred and ninety two New Zealand white rabbits were randomly divided into 4 groups (groups A, B, C and D). Corneal injury models were established in all groups. There were 48 experimental animals in each group. TGF-β2 ASON was dropped into right eyes in group A, dexamethasone was dropped into right eyes in group B, deionized water was dropped into right eyes in group C and nothing was dropped into right eyes in group D after the operation. The corneas were surgically removed and assessed by hematoxylin eosin (HE) staining, immunohistochemical study and real time PCR at four different time points (4 d, 7 d, 14 d and 28 d) after surgery. HE staining: at the same time point, fibroblasts in the groups A and B were significantly fewer than that in the groups C and D, the difference was statistically significant (P < 0.05), but there was no significant difference between groups A and B or groups C and D. Immunohistochemical observation found that the expression of α-smooth muscle actin (α-SMA) positive fibroblasts could be observed by the 4th day (9.44 ± 0.47/HP), reached a climax by the 7th day (12.50 ± 0.81/HP), and returned to the baseline levels by the 14th day (0.85 ± 0.43/HP) in the group A, which was similar to that in the group B (9.49 ± 0.95, 12.42 ± 0.70, 0.86 ± 0.79/HP) at the same time point (P > 0.05), but it was significantly fewer than that in the group C(20.14 ± 0.78, 18.19 ± 1.28, 4.87 ± 0.58/HP) and group D(20.21 ± 0.92, 18.25 ± 1.39, 5.00 ± 2.217/HP), which was statistical significant (P < 0.05). The staining intensity of fibronectin (FN) in groups A and B was significantly weaker than that in groups C and D. Real time PCR analysis showed that at each time point, the expression of TGF-β2 mRNAs in groups A and B was
Góes, Rejane Maira; Barbosa, Flávia Leão; De Faria-E-Sousa, Sidney Júlio; Haddad, Antonio
The investigation was centered on the morphological features of the conjunctiva-cornea transition (limbus) of the rabbit eye and the proliferative behavior of its epithelium. The eyes were processed for examination with light and electron microscopy, as well as for autoradiography after intravitreal injection of [(3)H]thymidine ([(3)H]TdR). At the sites of extraocular muscle insertion, the vascularization of the stroma extended to the peripheral cornea, and the limbal epithelium was thin with its basal stratum made up by clear cuboidal cells. In between the muscle insertions, the cuboidal clear cells, as well as the stroma blood vessels, were scarce. At the light microscope level, the basement membrane was distinct in the cornea but not in the limbus or the conjunctiva. Autoradiographs demonstrated that, at the limbus, the basal cells migrated very quickly to the suprabasal region and remained there up to the 28-day interval. Labeled cells were identified in all epithelial layers of the cornea, including the basal one, at 21 and 28 days but not in the limbal basal clear cells. The rate of renewal of conjunctival epithelium was similar to that observed for the transition with scarce clear cells. The high-resolution autoradiographs demonstrated that the basal cuboidal clear limbal cells exhibit a quick renewal and that they are not label-retaining cells. These latter ones were detected all over the corneal epithelium and in the suprabasal layers of the limbus up to 28 days, in physiological conditions, without the need of stimulation by damage to the corneal epithelium. (c) 2008 Wiley-Liss, Inc.
Santhiago, M R; Singh, V; Barbosa, F L; Agrawal, V; Wilson, S E
This study investigated whether PRM-151 (Promedior, Inc., Malvern, PA), a recombinant form of human pentraxin-2 (PTX-2, also referred to as serum amyloid P, hSAP), that inhibits differentiation of circulating monocytes into fibrocytes and profibrotic macrophages, could modulate generation of myofibroblasts after opacity-producing corneal injury in rabbits, and, therefore, have potential to reduce or prevent haze after PRK. Nine diopter PRK for myopia was performed with the VISX S4 IR laser. Four groups of 6 animals were treated in masked fashion: Group 1: 30 μl of topical PRM-151 (20 mg/ml) 6 times a day for 5 days; Group 2: 30 μl topical vehicle 6 times a day for 5 days; Group 3: 200 μl sub-conjunctival PRM-151 (total injection of 4 mg) immediately after surgery and every other day until day 8; Group 4: 200 μl sub-conjunctival injections of vehicle according to the same schedule as group 3. At one month after PRK, the animals were euthanized and immunohistochemistry was performed for the myofibroblast marker α-smooth muscle actin (SMA). The density of SMA+ cells/400× field in the central stroma was determined in each cornea. Myofibroblast density at one month after surgery was significantly lower (p = 0.006) after sub-conjunctival PRM-151 treatment (5.8 ± 2.8 cells/400× stromal field) compared to sub-conjunctival vehicle treatment (15.3 ± 2.9 cells/400× stromal field). There was no significant (p = 0.27) decrease in stromal myofibroblasts triggered by topical PRM-151 treatment (11.8 ± 6.6 cells/400× stromal field) compared to the topical vehicle treatment (14.2.8 ± 6.2 cells/400× stromal field). PRM-151 inhibits myofibroblast generation when administered by sub-conjunctival injection, but not when administered topically, after opacity-producing corneal injury. This study provides additional confirmation that bone marrow-derived cells contribute to corneal myofibroblast generation.
Abdelkader, Almamoun; Elewah, El-Sayed M; Kaufman, Herbert E
To compare wound healing and morphologic characteristics of the host-donor interface in rabbit corneas after maximum-depth and near-Descemet membrane anterior lamellar keratoplasty. Descriptive analysis of confocal microscopy images after 2 types of deep lamellar keratoplasty (deep stromal dissection vs total stromal resection). Deep anterior lamellar keratoplasty (DALK) was performed in 16 rabbit eyes, with exposure of the Descemet membrane in 8 eyes (deep group) and deep stromal dissection to near the Descemet membrane in 8 eyes (near group). A full-thickness graft devoid of endothelium and Descemet membrane was sutured in place. Confocal examination of lamellar interface and wound edge was performed throughout 6 months. Four days postoperatively, confocal microscopy revealed numerous highly reflective keratocytes at and adjacent to the interface in all eyes, fewer in the deep than the near group. Keratocyte density and reflectivity returned to normal at 4 to 6 weeks (deep) and 8 to 10 weeks (near) postoperatively. In the deep group, the smooth interface showed less scarring. In the near group, stroma-to-stroma healing stimulated more activated keratocytes and hence more haze. Successful DALK requires minimal central healing for clarity but significant suture-stimulated healing at the edge to prevent corneal bulge. Deep anterior lamellar keratoplasty is rarely accompanied by rejection, avoids entrance into the anterior chamber, and can be performed with tissue that does not have living keratocytes. Interface healing is a determinant of the final visual acuity; depth of the lamellar bed is a major determinant of the healing response. Although dissection to bare the Descemet membrane is more difficult, there is less keratocyte activation and scarring.
Pan, Shuling; Li, Li; Xu, Zhiyong; Zhao, Jiao
To explore the effect of leukemia inhibitory factor on corneal nerve regeneration in a rabbit model after laser in situ keratomileusis. Thirty five healthy New Zealand rabbits were divided into three groups for a 6-month observation, the blank control group, the control group, and the treatment group respectively. Laser in situ keratomileusis for myopia was performed on 30 rabbits (60 eyes in total) and then 1 μg/ml LIF eye drops were used four times a day on the left eyes as the treatment group, and the balanced salt solution (BSS) was used on the right eyes as the control group. Nerve regeneration was evaluated by counting the new regenerated nerves in golden chloride staining. The parameters for dry eye include Schirmer I test and tear break-up time were also examined. The number of regenerated nerve fibers in the treatment group was significantly higher than that in the control group at all time points except the 6th month after LASIK (P<0.05). The parameters for dry eye between two groups were compared at each postoperative time point and the results showed they were significantly higher in the LIF-treated group than in the BSS-control group at 2w, 1m, and 3m respectively. Leukemia inhibitory factor can effectively accelerate the corneal nerve regeneration of rabbit eyes after LASIK surgery and decrease the occurrence of dry eye symptoms. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.
Stroobants, A; Fabre, K; Maudgal, P C
We investigated the effect of 6 commercially available non-steroidal anti-inflammatory drug (NSAID) eye drops on the normal corneal epithelium of rabbits. Each drug was instilled into both eyes of 2 rabbits, 5 times a day, for 5 consecutive days. Two additional corneas of one rabbit, without any treatment, served as control. After treatment, the corneas were excised and processed for scanning electron microscopic evaluation. The epithelial changes induced by the drugs were graded by an empirical score system. All test compounds caused alterations in the cell membranes and surface microvilli, or even exfoliation and necrosis of surface cells. The extent of cell damage appeared to be related to the active ingredient in the eye drops, the pH of the solution, and the constituents of the vehicle, especially the type of preservative used.
Torricelli, Andre A. M.; Santhanam, Abirami; Agrawal, Vandana
Purpose To perform a masked study to determine whether resolvin E1 (RvE1), a lipid-derived immunomodulator, could regulate the development of corneal haze and opacity-related myofibroblasts after opacity-generating high correction photorefractive keratectomy (PRK) in rabbits. Methods Three groups of eight rabbits each were included in the study. Nine diopter (D) PRK for myopia was performed in each test cornea, and the eyes were treated with 30 µl of topical solution every 4 h (six times a day) for 5 days starting immediately after PRK. Group 1 was treated with 0.1% RX-10045, a prodrug of an RvE1 analog; group 2 was treated with 0.01% RX-10045; and group 3 was treated with vehicle control solution. At 1 month after PRK, haze was graded at the slit-lamp by a masked observer. Immunohistochemistry for α-smooth muscle actin (SMA) was performed on the central cornea of each test eye to determine the anterior stromal myofibroblast density. Results Corneal opacity was significantly lower in the 0.1% RX-10045 group, but not the 0.01% RX-10045 group, compared to the vehicle control group (p=0.029), at 1 month after −9.0D PRK. At 1 month after −9.0D PRK, SMA+ myofibroblast densities in the anterior stroma were not statistically significantly different among the three groups, although a trend toward lower myofibroblast generation was noted in the 0.1% RX-10045 group. Conclusions Topical 0.1% RX-10045, a prodrug of an RvE1 analog, reduces corneal opacity after haze-generating PRK in rabbits. Further studies are needed to determine the precise points at which RvE1 decreases corneal opacity after injury. PMID:25558174
Torricelli, Andre A M; Santhanam, Abirami; Agrawal, Vandana; Wilson, Steven E
To perform a masked study to determine whether resolvin E1 (RvE1), a lipid-derived immunomodulator, could regulate the development of corneal haze and opacity-related myofibroblasts after opacity-generating high correction photorefractive keratectomy (PRK) in rabbits. Three groups of eight rabbits each were included in the study. Nine diopter (D) PRK for myopia was performed in each test cornea, and the eyes were treated with 30 µl of topical solution every 4 h (six times a day) for 5 days starting immediately after PRK. Group 1 was treated with 0.1% RX-10045, a prodrug of an RvE1 analog; group 2 was treated with 0.01% RX-10045; and group 3 was treated with vehicle control solution. At 1 month after PRK, haze was graded at the slit-lamp by a masked observer. Immunohistochemistry for α-smooth muscle actin (SMA) was performed on the central cornea of each test eye to determine the anterior stromal myofibroblast density. Corneal opacity was significantly lower in the 0.1% RX-10045 group, but not the 0.01% RX-10045 group, compared to the vehicle control group (p=0.029), at 1 month after -9.0D PRK. At 1 month after -9.0D PRK, SMA+ myofibroblast densities in the anterior stroma were not statistically significantly different among the three groups, although a trend toward lower myofibroblast generation was noted in the 0.1% RX-10045 group. Topical 0.1% RX-10045, a prodrug of an RvE1 analog, reduces corneal opacity after haze-generating PRK in rabbits. Further studies are needed to determine the precise points at which RvE1 decreases corneal opacity after injury.
Hu, Jiaoyue; Zhang, Zhenhao; Xie, Hui; Chen, Lelei; Zhou, Yueping; Chen, Wensheng; Liu, Zuguo
To determine if a serine protease inhibitor A3K (SA3K) reduces TNF-α-induced declines in rabbit corneal endothelial junctional barrier integrity. New Zealand rabbit corneas were incubated ex vivo for 24 hours in Dulbecco's modified Eagle's medium (DMEM) containing 10% FBS with or without TNF-α, in the presence or absence of SA3K at different concentrations. Corneal endothelial barrier function permeability was determined based on measurements of FITC-dextran tissue accumulation. Apical junctional complex (AJC) integrity was evaluated of zonula occludens-1 (ZO-1), vascular endothelial (VE)-cadherin, and filamentous actin (F-actin) and associated microtubules, as well as myosin light chain (MLC) by immunofluorescent staining, Western blot analysis, and/or RT-PCR. TNF-α (20 ng/mL) increased corneal endothelial FITC-dextran permeability by 1.8-fold compared with the untreated control. SA3K (100-200 nM) dose dependently suppressed TNF-α-induced increases in permeability. SA3K nearly completely reversed TNF-α-induced disruptions of tight junctional ZO-1 and subjacent adherens junctions VE-cadherin integrity. Interestingly, SA3K reversed TNF-α-induced disruption of AJC linkage to the cytoskeletal F-actin array by restoring F-actin double-band structures. SA3K also attenuated TNF-α-induced microtubule disassembly. Furthermore, SA3K blocked increases in MLC phosphorylation status elicited by TNF-α. SA3K exposure markedly reduced TNF-α-induced disruption of barrier structure and function in the rabbit corneal endothelium by maintaining AJC integrity. These protective effects are due to suppression of MLC activation. SA3K may have, in vivo, a therapeutic potential to offset TNF-α-induced declines in endothelial barrier structural integrity and function.
Wieser, Barbara; Tichy, Alexander; Nell, Barbara
Guinea pigs have a very low threshold of corneal sensitivity and at the same time nearly no reflex tearing compared to dogs, cats, and horses. The question arose whether there is a general correlation between corneal sensitivity and the quantity of reflex tearing. Totally 160 animals of 8 different species (20 animals per species) were investigated. The corneal touch threshold (CTT) was measured with a Cochet-Bonnet esthesiometer. The palpebral fissure length (PFL) was measured with a calliper ruler. The Schirmer tear test (STT) was modified by adapting the width of the STT strip to the PFL of every species. For the STT II, 0.4% oxybuprocaine was applied. Corneal touch threshold: Cows (1.67 g/mm(2)), horses (1.23 g/mm(2)), sheep (1.13 g/mm(2)), goats (1.44 g/mm(2)), dogs (2.16 g/mm(2)), and cats (1.33 g/mm(2)) show similar CTT values. In contrast, rabbits (6.21 g/mm(2)) and guinea pigs (7.75 g/mm(2)) show a significantly lower CTT. Tear Production Difference STT I - STT II: Rabbits have the greatest decline in tear production with 38.4%, followed by sheep (33.3%), dogs (31.1%), cats (24.7%), cows (23.7%), horses (18.0%), and goats (14.0%). Guinea pigs have no decline, but a slight increase of -16.0%. Correlation CTT and STT II - STT I Difference: Pearson's correlation coefficient shows a small, but significant correlation. The coefficient of determination can only forecast a value with 7.1% certainty. The high variance and low reproducibility of results suggest that the measuring devices are inappropriate to assess the evaluated parameters. Therefore, no assured correlation between the corneal sensitivity and the quantity of reflex tearing could be found. © 2012 American College of Veterinary Ophthalmologists.
Sanders, Talia; Pujara, Tarak; Camelo, Serge; Lai, Ching Tat; Van Saarloos, Paul; Beazley, Lyn; Rodger, Jennifer
Corneal refractive surgery is typically performed using a 193-nm excimer laser. However, a recently developed 213-nm solid-state (5th harmonic) Nd:YAG laser presents some practical and user safety advantages, although the biological impact of using this wavelength remains poorly characterized. Here, we provide in vivo and in vitro comparisons of the corneal cellular outcomes after irradiation with 213 and 193 nm wavelengths. New Zealand White rabbits underwent photorefractive keratectomy with -5 diopters and a 6.5-mm optical zone and studied at time points up to 1 year. The development of haze was examined ophthalmologically and by detecting myofibroblasts immunohistochemically. Cell death was quantified using a terminal deoxynucleotidyl transferase-dUTP nick end labeling (TUNEL) assay, and the number of stromal keratocytes undergoing apoptosis estimated histologically. Superoxide dismutase activity was estimated in vitro by enzyme-linked immunosorbent assay in irradiated rabbit corneal keratocytes. Our results demonstrate subtle differences in the cellular outcomes after irradiation with 213- and 193-nm lasers, despite similar degrees of corneal haze developing in both treatment groups. In vivo, the 213-nm laser results in more stable stromal cell numbers, implying a more predictable ablation outcome. In vitro, higher levels of superoxide dismutase in corneal keratocytes irradiated with 213 nm compared with 193 nm wavelengths suggest a better endogenous protection against free radicals induced by laser surgery. The more favorable cellular responses after irradiation with 213 nm compared with 193 nm wavelengths are consistent with good clinical outcomes previously reported. Ablation with a 213 nm wavelength may result in better wound healing, leading to a more reliable correction of refractive errors.
Cosar, C Banu; Kucuk, Mutlu; Celik, Ekrem; Gonen, Tansu; Akyar, Isin; Serteser, Mustafa; Tokat, Fatma; Ince, Umit
To determine the effects of corneal collagen cross-linking (CXL) on the penetration of topical 0.5% moxifloxacin, on the number of colony-forming units (CFUs) in the cornea, and on the clinical course in a rabbit eye model of experimentally induced Pseudomonas aeruginosa keratitis. In this prospective animal study, experimental Pseudomonas corneal ulcers were induced in 56 corneas of 28 albino New Zealand rabbits. The corneas were randomly divided into the following 4 groups: the control group (14 eyes), the MOX group (moxifloxacin) (14 eyes), the MOX + CXL group (14 eyes), and the CXL group (14 eyes). On day 4 of the experiment, the eyes in the control group were enucleated and CFU counting was performed. On day 10 of the experiment, all eyes were enucleated and CFU counting was performed. In the MOX and MOX + CXL groups, the moxifloxacin level in the cornea, aqueous humor, iris, plasma, and serum was measured by reverse-phase high-performance liquid chromatography. The difference in the corneal CFU count between the MOX group and the MOX + CXL group was not significant (P = 0.317). Clinical improvement was greatest in the MOX + CXL group (P < 0.001). The mean corneal moxifloxacin level was 0.391 ± 0.09 μg·mg in the MOX group versus 0.291 ± 0.09 μg·mg in the MOX + CXL group; as such, CXL did not have a significant effect on antibiotic penetrance (P = 0.386). Clinical improvement was greatest in the MOX + CXL group. The synergistic effect of CXL on corneal ulcer treatment is not through antibiotic penetrance.
Zhou, Lei; Beuerman, Roger W; Huang, Liqun; Barathi, Amutha; Foo, Yong Hwee; Li, Sam F Y; Chew, Fook Tim; Tan, Donald
The cornea is the major refracting optical element of the eye and therefore critical for forming a retinal image. The exposed surface of the eye is protected from pathogens by the innate immune system whose components include defensins, naturally occurring peptides with antimicrobial properties, and the physical barrier formed by the outer epithelial layer of the cornea. The proteomic approach has revealed that tear levels of defensins are correlated with the course of healing of an experimental corneal wound. Tears were collected from New Zealand White rabbits prior to (day 0) and daily for 5 days (days 1-5) following a standard unilateral 6 mm diameter corneal epithelial abrasion. Tear protein profiles obtained from wounded and contra-lateral control eyes were compared using SELDI ProteinChip technology. Peptides and proteins of interest were purified by RP-HPLC and characterized by nanoESI-MS/MS. Mass spectra of tears on post-wound day 1, revealed 13 peaks whose level decreased and five that increased. During wound healing the tear protein profile correlated with wound closure. An important finding was that the levels of rabbit defensins (NP-1 and NP-2), which were elevated after wounding returned to normal levels by the time the corneal abrasion healed. Relative quantification of NP-2 in tear fluid prior to (day 0) and after corneal wounding (days 1- 3) was determined using iTRAQ technology. A corneal wound eliminates the barrier function of innate immunity and puts the cornea at risk from microbial attack until the epithelial cells restore the surface barrier. The increased availability of defensins in the tears during healing suggests that these peptides could protect the cornea from microbial attack during a period of increased vulnerability.
Yeh, Jeng-Hsien; Sun, Te-Kung; Chou, Chiang-Ting; Chen, Wei-Chuan; Lee, Jenn-Kuen; Yeh, Hsiao-Chun; Liang, Wei-Zhe; Kuo, Chun-Chi; Shieh, Pochuen; Kuo, Daih-Huang; Jan, Chung-Ren
The effect of sertraline, a selective serotonin reuptake inhibitor (SSRI), on cytosolic free Ca²⁺ concentrations ([Ca²⁺](i)) in a rabbit corneal epithelial cell line (SIRC) is unclear. This study explored whether sertraline changed basal [Ca²⁺](i) levels in suspended SIRC cells by using fura-2 as a Ca²⁺-sensitive fluorescent dye. Sertraline at concentrations between 10-100 μM increased [Ca²⁺](i) in a concentration-dependent manner. The Ca²⁺ signal was reduced by 23% by removing extracellular Ca²⁺. Sertraline induced Mn²⁺ influx, leading to quench of fura-2 fluorescence, suggesting Ca²⁺ influx. This Ca²⁺ influx was inhibited by phospholipase A₂ inhibitor aristolochic acid, but not by store-operated Ca²⁺ channel blockers and protein kinase C/A modulators. In Ca²⁺-free medium, pretreatment with the endoplasmic reticulum Ca²⁺ pump inhibitor thapsigargin, cyclopiazonic acid or 2,5-di-tert-butylhydroquinone greatly inhibited sertraline-induced Ca²⁺ release. Inhibition of phospholipase C with U73122 abolished sertraline-induced [Ca²⁺](i) rise. At concentrations of 5-50 μM, sertraline killed cells in a concentration-dependent manner. The cytotoxic effect of 25 μM sertraline was not reversed by prechelating cytosolic Ca²⁺ with BAPTA/AM. Collectively, in SIRC cells, sertraline induced [Ca²⁺](i) rises by causing phospholipase C-dependent Ca²⁺ release from the endoplasmic reticulum and Ca²⁺ influx via phospholipase A₂-sensitive Ca²⁺ channels. Sertraline-caused cytotoxicity was mediated by Ca²⁺-independent pathways.
Lima, Leandro; Lange, Rogério Ribas; Turner-Giannico, Amália; Montiani-Ferreira, Fabiano
To evaluate endodontic paper point tear test (PPTT) in rabbits and compare changes in corneal touch threshold (CTT) induced by Schirmer tear test (STT) and PPTT. Normal corneal sensitivity recovery time after both tear tests was also measured. Also, mean PPTT and STT values were obtained. Tear production of 20 eyes, from 10 rabbits, was evaluated using STT and the PPTT. Central corneal touch threshold was measured by a Cochet-Bonnet esthesiometer before any tear test was performed (zero time), immediately after the test (1 min), and consecutively at 6, 11, 16, and 26 min. Tests were conducted on three consecutive days: Day 1 - control condition, no tear tests performed only the CTT; Day 2 - CTT before and after PPTT; and Day 3 - CTT before and after STT. CTT values were compared using repeated measures ANOVA. Corneal touch threshold was significantly increased for at least 16 min after STT, indicating STT causes corneal discomfort. No difference was found between CTT following PPTT and controls, indicating PPTT caused minimal corneal discomfort. The mean (±SD) value for STT was 5.2 ± 1.0 mm/min and for PPTT was 13.8 ± 1.5 mm/min. The aqueous fraction of rabbit's tears can be successfully measured by PPTT. This report established reference values for PPTT in rabbits. Additionally, the absence of a significant difference in CTT after PPTT compared with controls shows that PPTT is well tolerated by rabbits. Considering the improved comfort (compared with STT), accuracy, and low cost, PPTT is a bona fide method of measuring aqueous tear production in rabbits. © 2014 American College of Veterinary Ophthalmologists.
Hodson, S A; Lawton, D M
1. Rabbit corneal thickness changes were measured after some of the NaCl in the bathing Ringer solution was substituted by a neutral sugar. 2. The response had three phases which could be closely modelled by three exponentials of different amplitudes and rate constants, originating from the time of the substitution. 3. The first, fastest, phase was interpreted as being driven by the pure osmotic pressure difference developed across the corneal endothelium by the difference between the removed NaCl and the added sugar in the bathing Ringer solution; the second was driven by the diffusion of NaCl out of the stroma; and the third, slowest, phase was driven by the diffusion of the added sugar into the stroma. 4. Consistent with the interpretation, only the third, slowest, phase had its rate constant dependent upon the nature of the substituting neutral sugar. 5. The amplitude of the pure osmotic phase was a linear function of the added sugar. Its amplitude was zero when an equal osmolarity of sugar was substituted for NaCl. 6. It was concluded that the reflexion coefficient of rabbit corneal endothelium to NaCl is the same as that to sucrose, raffinose and stachyose, i.e. about 1. 7. The calculated hydraulic conductivity of the endothelium plus stroma was about the same as that of stroma alone, and it was concluded that the hydraulic conductivity of corneal endothelium is large compared to corneal stroma. 8. It is proposed that most of the hydraulic flow in response to osmotic gradients passes through the cells, whereas salt diffuses through the paracellular route, resulting in an apparent reflexion coefficient of 1. 9. Thus, corneal endothelium is a 'leaky' (12 omega cm2) salt-permeable epithelium and, according to the present study, simultaneously a semi-permeable membrane. To resolve the terminology, we suggest the term 'bi-permeable' for such epithelia which have a high salt permeability but such a very high water permeability as to give apparent reflexion
Nien, Chyong Jy; Flynn, Kevin J.; Chang, Melissa; Brown, Donald; Jester, James V.
PURPOSE To compare the effects of topical cyclosporine A 0.05% (Restasis) with those of prednisolone acetate 1.00% (Pred Forte) on corneal haze after photorefractive keratectomy (PRK). SETTING Gavin Herbert Eye Institute, University of California, Irvine–Orange, California, USA. DESIGN Experimental study. METHODS After −9.00 diopter PRK, 15 rabbits were divided into 3 groups and treated for 4 weeks with prednisolone acetate 1.00% or cyclosporine A 0.05% or neither (control). Corneal haze was measured by in vivo confocal microscopy preoperatively and 2, 4, 6, 8, and 12 weeks postoperatively. At 12 weeks, the corneas were evaluated for collagen organization by ex vivo 2-photon second-harmonic generation and stromal cell density. RESULTS Corneal haze was significantly less in the prednisolone acetate group than in the cyclosporine and control groups during the first 6 weeks postoperatively (P < .02). At 8 weeks, there was no significant difference between the 3 groups. There was no significant difference in haze between the cyclosporine group and control group at any time. The stroma was also significantly thinner in the prednisolone acetate group than in the other groups for the first 4 weeks postoperatively (P < .02). Second-harmonic generation scar thickness measurements at 12 weeks were not significantly different between the groups, although the prednisolone acetate group tended to have lower stromal cell density. CONCLUSION Cyclosporine A 0.05% had no effect on wound healing after PRK, while prednisolone acetate 1.00% significantly reduced peak corneal haze but had no effect on long-term corneal haze after discontinuation of the drug. PMID:21406325
Liu, Chengxing; Feng, Pengfei; Li, Xiaona; Song, Jie; Chen, Weiyi
Refractive surgery not only leads to tissue injury but also evokes mechanical stress increase of the cornea. How the mechanical stress affects the corneal matrix remodeling, specifically, matrix metalloproteinases (MMPs) and their inhibitors (tissue inhibitors of metalloproteinases; TIMPs) is not well understood. In this study, cultured rabbit corneal fibroblasts in vitro were subjected to regimen of 5%, 10%, or 15% equibiaxial stretch at 0.1 Hz for 3 or 24 h. MMP-2 protein level was measured by gelatin zymography and Western blotting. MMP-2, membrane type 1 MMP (MT1-MMP), and TIMP-2 mRNA levels were quantified by real-time quantitative PCR. Extracellular regulated protein kinase (ERK) phosphorylation protein levels were assessed by Western blotting. Our results showed that a 15% stretch resulted in increases in MMP-2 protein, MMP-2 mRNA, and MT1-MMP mRNA levels, but a decrease in TIMP-2 mRNA level. However, a 5% stretch caused decreases in MMP-2 protein and mRNA level, but an increase in TIMP-2 mRNA level, and no change in MT1-MMP mRNA level. A 15% stretch also caused a significant increase in ERK1/2 phosphorylation. Inhibition of the mitogenactivated protein kinase (MEK) pathway with PD98059 attenuated stretch-induced increase in MMP-2 production and ERK activity. These results suggest that small-magnitude stretching may promote corneal matrix synthetic events, whereas large-magnitude stretching promotes corneal matrix degradation by changing the balance between MMPs and TIMPs in corneal fibroblasts. Large-magnitude stretch-induced increase in pro-MMP-2 production was in an ERK-dependent manner. © 2014 by the Society for Experimental Biology and Medicine.
Foltz, Michael S.; Denton, Michael L.; Schuster, Kurt J.; Estlack, Larry E.; Kumru, Semih S.
Corneal organotypic cultures were generated as per existing methods, which included growth on polycarbonate inserts and air-lifting for one week. The corneal simulant cultures were exposed, with real-time IR imaging, to the 2-μm wavelength output of a thulium fiber laser with 4 mm beam diameter for 0.25 seconds in a thermally controlled environment and then assayed for damage. The in vitro threshold (ED 50 value of 12.5 W/cm2) and peak temperature (74.5 °C) at threshold irradiance are compared with rabbit corneal data in the literature.
Sitalakshmi, G; Sudha, B; Madhavan, H N; Vinay, S; Krishnakumar, S; Mori, Yuichi; Yoshioka, Hiroshi; Abraham, Samuel
We evaluated the efficacy of autologous expanded corneal epithelial cell transplants derived from harvested limbal biopsy cultured on a thermoreversible polymer (Mebiol Gel) for the management of unilateral limbal stem cell deficiency (LSCD). Corneal limbal biopsies from 12 rabbits were cultured on a thermoreversible polymer Mebiol Gel at 37 degrees C. Cells were harvested from the dishes after 3 weeks by reducing temperature to 4 degrees C. Autologous transplantation was undertaken to reconstruct the experimentally induced limbal stem cell deficiency in the rabbit eyes. The corneas of both eyes of all rabbits were harvested later for molecular studies. Reparative surgery was a total success in seven rabbits, partial success in two, and failure in three eyes. Histology of the seven successful eyes showed the successful growth of the corneal epithelium. Immunohistochemistry and reverse transcriptase polymerase chain reaction showed the cornea phenotype and stem cell-associated markers in the limbus of the seven successful eyes, indicating the homing of these cells into limbus. In the three failure cases and in the two control rabbit eyes, used in the study, histology showed presence of goblet cells and vascularization in the stroma with abortive formation of corneal epithelium. Our results suggest that transplantation of autologous limbal epithelial cells grown in thermoreversible polymer Mebiol Gel may restore a nearly normal ocular epithelial surface in eyes with unilateral LSCD.
Yamada, Keiko; Young, Robert D; Lewis, Philip N; Shinomiya, Katsuhiko; Meek, Keith M; Kinoshita, Shigeru; Caterson, Bruce; Quantock, Andrew J
To investigate whether mesenchymal-epithelial cell interactions, similar to those described in the limbal stem cell niche in transplant-expired human eye bank corneas, exist in freshly enucleated rabbit eyes and to identify matrix molecules in the anterior limbal stroma that might have the potential to help maintain the stem cell niche. Fresh limbal corneal tissue from adult Japanese white rabbits was obtained and examined in semithin resin sections with light microscopy, in ultrathin sections with transmission electron microscopy, and in three-dimensional (3D) reconstructions from data sets of up to 1,000 serial images from serial block face scanning electron microscopy. Immunofluorescence microscopy with five monoclonal antibodies was used to detect specific sulfation motifs on chondroitin sulfate glycosaminoglycans, previously identified in association with progenitor cells and their matrix in cartilage tissue. In the rabbit limbal cornea, while no palisades of Vogt were present, the basal epithelial cells stained differentially with Toluidine blue, and extended lobed protrusions proximally into the stoma, which were associated with interruptions of the basal lamina. Elongate processes of the mesenchymal cells in the superficial vascularized stroma formed direct contact with the basal lamina and basal epithelial cells. From a panel of antibodies that recognize native, sulfated chondroitin sulfate structures, one (6-C-3) gave a positive signal restricted to the region of the mesenchymal-epithelial cell associations. This study showed interactions between basal epithelial cells and subjacent mesenchymal cells in the rabbit corneal limbus, similar to those that have been observed in the human stem cell niche. A native sulfation epitope in chondroitin sulfate glycosaminoglycans exhibits a distribution specific to the connective tissue matrix of this putative stem/progenitor cell niche.
Ozmen, Mehmet Cuneyt; Hondur, Ahmet; Yilmaz, Guldal; Bilgihan, Kamil; Hasanreisoglu, Berati
To evaluate the histological changes after transepithelial corneal crosslinking (CXL) using partial thickness excimer laser ablation or epithelial ethanol application in an experimental rabbit study. Right eyes of twenty-four rabbits were studied. Four eyes received total epithelial debridement (group I). Four eyes received partial thickness epithelial ablation with excimer laser (group II). Twelve eyes were treated with different durations (30s and 60s) and concentrations (18% to 48%) of ethanol (group III). Riboflavin was applied for 30min intervals along with topical proparacaine drops with benzalkonium chloride, and 370 nm irradiation was performed for 30min, while riboflavin was instilled every 3min. Four eyes (group IV) received 48% ethanol for 30s without riboflavin and irradiation. Eyes were collected after 24h and examined histologically. All eyes in group I showed keratocyte loss in the superficial 300 µ of corneal storma. In group II, 1-4 layers of epithelium were preserved and no keratocyte loss occurred. In group III, CXL after treatment with ethanol up to 24% concentration and up to 60s revealed no keratocyte loss. CXL after treatment with 48% and higher ethanol concentrations yielded keratocyte loss in the superficial 200 µ to 300 µ of cornea. Incomplete excimer laser ablation of the epithelium or treatment with ethanol up to 24% concentration and up to 60s duration yielded no stromal keratocyte loss. To get the same histological appearance seen in epithelial debridement group, partial thickness excimer laser epithelial ablation or ethanol application is not adequate for transepithelial CXL.
Liu, Lin; Li, Yongping; Huang, Shuqi; Lin, Jianxian; Zhang, Wenxin
To determine whether the topical application of keratinocyte growth factor-2 (KGF-2) can enhance corneal epithelial healing in rabbit alkali burned cornea. In addition, the distribution and proliferation of corneal epithelial stem cells in KGF-2-treated and control corneas were investigated to explain their mechanisms of effects on the epithelium. Twenty-four New Zealand eyes were divided into four groups, treated with KGF-2 solution (1, 50, 100 microg/ml) and PBS solution. Eighth millimeter filter paper discs, produced by standard paper punch, were soaked for 15 sec in 0.5N NaOH solution. The alkali-soaked discs were applied to the central cornea, centered on the pupil and held gently in position with forceps for 1 min. The cornea was finally irrigated over 1 mm with 100 ml balanced salt solution (BSS). Keratinocyte growth factor-2 was then applied topically three times a day. The phosphate-buffered saline (PBS) group was served as a control. Each corneal epithelial defect was subsequently photographed every 24 hours with a slit lamp and was measured by computer-assisted digitizer. In each group, two rabbits were sacrificed for light microscopic examination after the interval of 7, 14 and 21 days. Meanwhile, the cornea epithelium was examined hy immunohistochemistry for P63, AE5, EGFR. Topical application of 10 microg/ml to 100 microg/ml KGF-2 significantly accelerated corneal epithelial wound healing when compared with controls. After 24 hours, epithelial healing rate of the 100 microg/ml KGF-2 group and the PBS treated group was (74 +/- 6)% and (40 +/- 8)% (P < 0.05). After 48 hours, the rate of the C group was (94 +/- 6)%, whereas in the control group it was (73 +/- 12)% (P < 0.05). Epithelial defects were often recurrent, which happened only two times in the 100 microg/ml KGF-2-treated group, but many times in the control group. In the corneal epithelial stem cell analysis, the number of the P63 positive cells was higher in the KGF-2-treated
Góes, Rejane Maira; Barbosa, Flávia Leão; de Faria-E-Sousa, Sidney Júlio; Kajiwara, João Kazuyuki; Haddad, Antonio
Damage to the corneal epithelium causes not only a reaction for its repair but also affects other parts of the cornea as well as different components of the anterior segment of the eye. The purpose of this investigation was to analyze the consequences, following epithelial and limbal damage, to the iris of rabbits (Oryctolagus cuniculus). The corneal epithelium was thoroughly scraped followed by surgical excision of the limbus. Next, (3)H-thymidine ((3)H-TdR) was injected intravitreally both into the right (experimental) and left (control) eyes which had their anterior segments processed for autoradiography at intervals of 2, 7 and 21 days after surgery (three rabbits per interval). The irises were also examined with scanning-electron and confocal microscopy after Evans blue injection. There was a high frequency of labeling in the cells of the iris blood vessels in the experimental eye, particularly the endothelial ones. The ratio of labeled cells between experimental and control irises was 40:1, with a population of nuclei increasing by 25% and remaining labeled up to 21 days. There was also an increase in the volume of the iris vasculature as shown by confocal microscopy. The high labeling frequencies of the vascular cells were observed throughout the iris from the ciliary to the pupillary regions. The lesions on the corneal epithelium elicit proliferation of the iris vascular cells, mainly its endothelium, as well as an early breakdown of the blood-aqueous barrier. The daughter cells resulting from the damage to the eye surface were detected up to 21 days after a single injection of (3)H-TdR, most likely due to their slow turnover. As a consequence of this proliferation, the vasculature of the iris increased in volume.
Gallhoefer, Nicolin S; Spiess, Bernhard M; Guscetti, Franco; Hilbe, Monika; Hartnack, Sonja; Hafezi, Farhad; Pot, Simon A
CXL penetration depth is an important variable influencing clinical treatment effect and safety. The purposes of this study were to determine the penetration depth of CXL in rabbit and equine corneas in epithelium-on and epithelium-off procedures and to assess an ex vivo fluorescent biomarker staining assay for objective assessment of CXL penetration depth. CXL treatment was performed according to a standardized protocol on 21 and 17 rabbit eyes and on 12 and 10 equine eyes with and without debridement, respectively. Control corneas were treated similarly, but not exposed to CXL. Hemicorneas were stained with either phalloidin and DAPI to visualize intracellular F-actin and nuclei, or with hematoxylin and eosin. Loss of actin staining was measured and compared between groups. Epithelium-off CXL caused a median actin cytoskeleton loss with a demarcation at 274 μm in rabbits and 173 μm in horses. In non-CXL-treated controls, we observed a median actin cytoskeleton loss with a demarcation at 134 μm in rabbits and 149 μm in horses. No effect was detected in the epithelium-on procedure. CXL penetration depth, as determined by a novel ex vivo fluorescent assay, shows clear differences between species. A distinct effect was observed following epithelium-off CXL treatment in the anterior stroma of rabbits, but no different effect was observed in horses in comparison with nontreated controls. Different protocols need to be established to effectively treat equine patients with infectious corneal disease. © 2015 American College of Veterinary Ophthalmologists.
Song, Jong-Suk; Lee, Jeong Goo; Kay, EunDuck P
To determine whether the elevated level of interleukin (IL)-1beta in aqueous humor after transcorneal freezing upregulates FGF-2 synthesis in rabbit corneal endothelium through PI3-kinase and p38 pathways. Transcorneal freezing was performed in New Zealand White rabbits to induce an injury-mediated inflammation. The concentration of IL-1beta was measured, and the expression of FGF-2, p38, and Akt underwent Western blot analysis. Intracellular location of FGF-2 and actin cytoskeleton was determined by immunofluorescence staining. Massive infiltration of polymorphonuclear leukocytes (PMNs) to the corneal endothelium was observed after freezing, and IL-1beta concentration in the aqueous humor was elevated in a time-dependent manner after freezing. Similarly, FGF-2 expression was increased in a time-dependent manner. When corneal endothelium was stained with anti-FGF-2 antibody, the nuclear location of FGF-2 was observed primarily in the cornea after cryotreatment, whereas FGF-2 in normal corneal endothelium was localized at the plasma membrane. Treatment of the ex vivo corneal tissue with IL-1beta upregulated FGF-2 and facilitated its nuclear location in corneal endothelium. Transcorneal freezing disrupted the actin cytoskeleton at the cortex, and cell shapes were altered from cobblestone morphology to irregular shape. Topical treatment with LY294002 and SB203580 on the cornea after cryotreatment blocked the phosphorylation of Akt and p38, respectively, in the corneal endothelium. These inhibitors also reduced FGF-2 levels and partially blocked morphologic changes after freezing. These data suggest that after transcorneal freezing, IL-1beta released by PMNs into the aqueous humor stimulates FGF-2 synthesis in corneal endothelium via PI3-kinase and p38.
Qiu, Xiao-di; Gong, Lan; Chen, Min-jie
Randomized controlled experimental study to investigate the influence of vitamin A palmitate and bovine recombinant basic fibroblast growth factor (bFGF) on repair of mechanical corneal epithelial defects, conjunctival epithelial cells and goblet cells in rabbits. One hundred and twenty New Zealand rabbits (all males) were selected to establish the mechanical corneal epithelial defects models (scratching out a round area with the diameter of 8 mm in the centre of cornea). Forty eight New Zealand rabbits were randomly divided into 4 groups: group A used lincomycin hydrochloride eye drops (LED) after the model had been established; group B used vitamin A palmitate eye gel and LED; group C used recombinant bFGF eye gel and LED; group D used vitamin A palmitate eye gel, bFGF eye gel and LED. Photo slit lamp examination and measurement of repaired area were performed on day 0, day 1, day 4 and day 7; transmission electron microscopy, histological microscope examination and impression cytology were performed on day 0, day 1, day 4 and day 7 to analysis the morphology and repairment of corneal epithelium, conjunctival epithelial cells and the goblet cells. The variants were tested using analysis of variance and Tukey's test. Statistic analysis showed that on day 1, the size of areas of repaired corneal epithelium was: group A(53.512 +/- 18.850) mm(2), group B (92.194 +/- 14.367) mm(2), group C (89.779 +/- 20.535) mm(2), group D (127.816 +/- 16.379) mm(2). The difference in size of repaired areas between different groups was statistically significant (F = 17.663, P = 0.000), with exception of the difference between groups B and C (P = 0.995). Conjunctival impression cytology showed that, the average number of conjunctival goblet cells per 740 microm x 550 microm at day 1 was decreased, group A (10.083 +/- 4.441), group B (10.667 +/- 3.551), group C (9.583 +/- 4.502), group D (9.167 +/- 5.606). The difference between these four groups was not significant (F = 0.239, P = 0
Nishiofuku, Hideyuki; Matsushima, Shigeru; Taguchi, Osamu; Inaba, Yoshitaka; Yamaura, Hidekazu; Sato, Yozo; Tanaka, Toshihiro; Kichikawa, Kimihiko
Equivalent cross-relaxation rate (ECR) imaging (ECRI) is a measurement technique that can be used to quantitatively evaluate changes in structural organization and cellular density by MRI. The aim of this study was to evaluate the correlation between the ECR value and cellular density in the rabbit VX2 tumor model. Five rabbits implanted with 10 VX2 tumors in the femur muscles were included in this study. We adopted the off-resonance technique with a single saturation transfer pulse frequency of 7 ppm downfield from water resonance. The ECR value was defined as the percentage of signal loss between the unsaturated and saturated images. ECR images were constructed based on the percentage of the ECR value. Pathological specimens were divided into 34 areas and classified into two groups: the viable group and the necrotic group. ECR values were measured and compared between groups. The correlation between the ECR value and cellular density was then determined. The mean ECR value was significantly higher in the viable group than in the necrotic group (61.2% vs. 35.8%). The area under the curve that calculated by receiver operating characteristic curve was 0.991 at 7 ppm. The regression graph showed a linear relationship between the ECR value and cellular density; the correlation coefficient (r) was 0.858. There is a strong association between the ECR value and cellular density in VX2 tumors and so ECRI could be a potentially useful technique for accurately depicting viable and necrotic areas.
Ozmen, Mehmet Cuneyt; Hondur, Ahmet; Yilmaz, Guldal; Bilgihan, Kamil; Hasanreisoglu, Berati
AIM To evaluate the histological changes after transepithelial corneal crosslinking (CXL) using partial thickness excimer laser ablation or epithelial ethanol application in an experimental rabbit study. METHODS Right eyes of twenty-four rabbits were studied. Four eyes received total epithelial debridement (group I). Four eyes received partial thickness epithelial ablation with excimer laser (group II). Twelve eyes were treated with different durations (30s and 60s) and concentrations (18% to 48%) of ethanol (group III). Riboflavin was applied for 30min intervals along with topical proparacaine drops with benzalkonium chloride, and 370 nm irradiation was performed for 30min, while riboflavin was instilled every 3min. Four eyes (group IV) received 48% ethanol for 30s without riboflavin and irradiation. Eyes were collected after 24h and examined histologically. RESULTS All eyes in group I showed keratocyte loss in the superficial 300 µ of corneal storma. In group II, 1-4 layers of epithelium were preserved and no keratocyte loss occurred. In group III, CXL after treatment with ethanol up to 24% concentration and up to 60s revealed no keratocyte loss. CXL after treatment with 48% and higher ethanol concentrations yielded keratocyte loss in the superficial 200 µ to 300 µ of cornea. CONCLUSION Incomplete excimer laser ablation of the epithelium or treatment with ethanol up to 24% concentration and up to 60s duration yielded no stromal keratocyte loss. To get the same histological appearance seen in epithelial debridement group, partial thickness excimer laser epithelial ablation or ethanol application is not adequate for transepithelial CXL. PMID:25540746
Schmitz, Klaus; Schreiber, Wolfram; Behrens-Baumann, Wolfgang
The aim of the presented experimental work was to develop a technique for congruent trephination of donor and recipient corneas in free form using a 193-nm excimer laser and to study the clinical follow-up after the application of the technique in a rabbit model. In 12 New Zealand White rabbits homologous penetrating keratoplasty was performed. Trephination of donor buttons and recipient beds was achieved in six animals by conventional mechanical trephination and in six by excimer laser trephination with a guided laser beam in a non-circular geometry. The surgical procedure and its applicability to human subjects were evaluated and the postoperative clinical course was followed for 6 months. The surgical procedure of full-thickness excimer laser trephination could be performed reproducibly in the animal model both for dissection of the donor buttons and for preparation of the recipient beds. Keratoplasty was performed with kidney-shaped transplants after trephination in free form with the guided laser beam. Postoperative clinical follow-up did not show any differences between the two trephination groups that could be related to the applied trephination technique. After 6 months we observed well-adapted and clear corneal grafts, kidney-shaped in the excimer trephination group and circular in the mechanical trephination group. No side effects on the crystalline lens and the central retina could be clinically observed following excimer laser trephination. We present the first experimental study of keratoplasty with freely selected transplant geometry and perfect congruence of donor button and recipient bed. The application of this technique in certain corneal disorders in humans will offer improved treatment options in the future.
Yamaguchi, Masahiro; Shima, Nobuyuki; Kimoto, Miwa; Ebihara, Nobuyuki; Murakami, Akira; Yamagami, Satoru
To optimize cultured human corneal endothelial cell (cHCEC) sheet transplantation technique for maintenance of cHCEC viability. cHCEC sheets cultured on a collagen scaffold were covered with or without Viscoat® and exposed to humidified air in the incubator. cHCEC sheets with or without Viscoat® were transplanted into cadaveric porcine eyes by the DSAEK technique with full air tamponade and incubated for various time periods. Then cell viability was determined by using the live/dead assay kit. cHCEC sheets with Viscoat® were transplanted into rabbit eyes and the sheets were histologically evaluated before and 14 days after transplantation. A collagen scaffold and Viscoat® were effective for protecting cHCEC from damage due to air exposure in vitro. All cells died after 18 hours of air exposure in porcine eyes in Viscoat® untreated control. In contrast, Viscoat® treatment sustained full cell viability following 2 hours and could maintain approximately 80% viability after 18 hours. In a rabbit model, transplanted cHCEC sheet with Viscoat® maintained cell density at 2803 ± 229 mm(2) (18% cell loss) and expression of N-cadherin, zonula occludens-1, and actin-filament localized to cell boundary as similar as donor HCEC. Viscoat® can contribute to cHCEC protection from damage caused by exposure to air.
Goskonda, V R; Khan, M A; Hutak, C M; Reddy, I K
The purpose of this study was to evaluate the permeability characteristics of a previously reported in vitro corneal model that utilizes SIRC rabbbit corneal cells and to investigate the permeability of three novel esters of phenylephrone chemical delivery systems (CDS) under different pH conditions using this in vitro model. The SIRC rabbit corneal cell line was grown on transwell polycarbonate membranes, and the barrier properties were assessed by measuring transepithelial electrical resistance (TEER) using a voltohmmeter. The permeabilities of esters of phenylephrone CDS across the SIRC cell layers were measured over a pH range 4.0-7. 4. The esters tested include phenylacetyl (1), isovaleryl (2), and pivalyl (3). The SIRC rabbit corneal cell line, when grown on permeable filters, formed tight monolayers of high electrical resistance with TEER values increasing from 71.6 +/- 20.8 Omega.cm2 at day 3 in culture to 2233.42 +/- 15.2 Omega.cm2 at day 8 in culture and remained constant through day 14 in culture. The transepithelial permeability coefficients (Papp) at pH 7.4 ranged from 0.58 x 10(-6) cm/s for the hydrophilic marker, mannitol, to 43. 5 x 10(-6) cm/s for the most lipophilic molecule, testosterone. The Papp at pH 7.4 for phenylephrine was 4.21 x 10(-6) cm/s. The Papp values and the lag times of the three esters of phenylephrone were pH dependent. The Papp for 1, 2, and 3 at pH 7.4 were 14.76 x 10(-6), 13.19 x 10(-6), and 12.86 x 10(-6) cm/s, respectively and the permeabilities decreased at conditions below pH 7.4. The lag times at pH 7.4 were 0.10, 0.17, and 0.12 h for 1, 2, and 3, respectively, and the values increased at lower pH conditions. The TEER values of SIRC cell line observed at day 8 to day 14 in the present investigation are similar to the resistance value reported for rabbit cornea (2 kOmega.cm2). All the esters showed significantly (p < 0.05) higher permeabilities than phenylephrine at pH 7.4. The rate and extent of transport of the drugs
Konstantinovsky, A A; Krasnov, M S; Yamskova, V P; Rybakova, E Yu; Yamskov, I A
We compared wound-healing activity of bioregulators isolated from cattle cornea, serum, and retinal pigment epithelium on in vivo model of experimental corneal injury in rabbits. Bioregulators were instilled into the eye as solutions at a concentration corresponding to 10(-12) mg protein/ml. The animals were sacrificed on day 21 after injury and the corneas were examined histologically. The best wound-healing effect was produced by bioregulators isolated from the cornea and serum and instilled successively into rabbit eyes with an interval of 15-20 min twice a day: multicellular epithelium was observed in the wound, and slight inflammation, in the stroma.
Durak, Ismet; Gürdal, Mehmet; Baysal, Kemal; Ates, Halil; Ozbek, Zeynep; Wang, Zheng; Wu, Albert; Wolosin, J. Mario
Purpose To determine the corneal regenerative capacity of sequentially generated primary, secondary, and tertiary limbal explant outgrowths in a limbal stem cell deficiency (LSCD) surgical model. Methods Two-millimeter-long limbal shallow biopsies were surgically excised from the upper quadrant of the right eye of rabbits and set on preserved amniotic membrane for explant culture. After the generation of primary outgrowth, the biopsies were sequentially transferred to new amniotic membrane to generate secondary and then tertiary outgrowths. Eighteen rabbits were subjected to a 360° limbal peritomy extending into the scleral zone and combined with superficial keratectomy of the corneal periphery and thorough mechanical debridement of the central cornea in their left eye. Right eye outgrowths, six of each generation, were engrafted on the ocular surface. Clinical outcomes (neovascularization, corneal clarity, and corneal fluorescein staining) were graded after 6 months. Post-mortem corneas were compared with histology, immunochemistry for p63 and Krt3, ABCG2-dependent dye exclusion, and capacity for outgrowths in explant culture. Results Immunohistology and western blot of the outgrowths for p63 and Krt3 indicated no differences in expression between the primary and tertiary outgrowths for these two markers of growth and differentiation. Clinically, all rabbits treated with amniotic membrane alone developed severe LSCD. Most rabbits grafted with cell outgrowths from all three outgrowth generations achieved stable (>6 months) recovery of the ocular surface. There were partial failures of grafts performed with two secondary and tertiary outgrowths. However, Kruskal–Wallis statistical analysis of the clinical scores yielded no significant difference between the three groups (p=0.524). Histology showed full anatomic recovery of grafts made with primary and tertiary outgrowths. Krt3 and p63 expression throughout the whole limbal corneal epithelium with primary or
Varsamidou, Efterpi; Markopoulou, Soultana; Karayannopoulou, Georgia; Kalpatsanidis, Antonis; Kokkas, Vassileios; Karampatakis, Vassileios; Goulas, Antonis
To study the effect of acute exposure of rabbit eyes to artificial sunlight in vivo, on the integrity of corneal and conjunctival tissue as well as on the gene expression of the receptor for platelet activating factor (PAFR). New Zealand albino rabbits were immobilized opposite a 300 W Osram Ultra-Vitalux® light bulb with an emission radiation spectrum similar to that of normal sunlight at noon, and exposed to ultraviolet B radiation in the range of the reported threshold for corneal damage. Corneal and third eyelid tissue samples were removed from exposed eyes at 2, 6 and 24 h following the end of the exposure to the bulb light and were subsequently processed for histochemical staining and RNA extraction. The gene expression of PAFR was detected with real time reverse transcription polymerase chain reaction. Some epithelial shedding was detected in the corneal tissue as a result of acute exposure to artificial sunlight. In the eyelid conjunctiva, a marked accumulation of eosinophils was noticed, as early as 2 h post-exposure, apparently directed toward the upper part of the epithelial layer. This effect appears to subside by hour 24. No statistically significant changes in gene expression were detected in the corneal tissue, whereas in the third eyelid, PAFR gene expression was significantly induced, most prominently at t = 2 and 6 h post-exposure. Acute exposure of rabbit eyes to artificial sunlight induced a marked infiltration of eosinophils into the epithelial layer of the conjunctiva but no gross alterations in the cornea or the third eyelid. The gene expression of PAFR was upregulated, as an effect of light exposure, in the third eyelid but not in the cornea.
Twa, Michael D; Giese, Michael J
To determine the repeatability of corneal thickness and keratocyte density using in vivo confocal scanning laser microscopy in a rabbit model of laser in situ keratomileusis. Prospective, experimental animal study. En face tomographic images of corneal tissue were captured from 5 New Zealand white rabbits. Central corneal thickness was compared with conventional ultrasonic pachymetry. Keratocyte density was measured as a function of stromal depth at baseline and 6 weeks after a 130-μm lamellar incision in the following regions: first countable stromal image (30 to 39 μm), anterior stroma (40 to 75 μm), incision zone (76 to 150 μm), mid stroma (151 to 250 μm), and deep stroma (251 to 400 μm). The mean residual difference between ultrasonic and confocal corneal thickness measurements was 2.1 μm (95% confidence interval [CI], -7.0 to 11.2 μm; P = .61). Before the lamellar incision, keratocyte density was highest in the first countable frame of the anterior stroma, 53 800 cells/mm(3) (95% CI, 35 000 to 72 000 cells/mm(3)) and was least in deep stroma, 27 100 cells/mm(3) (95% CI, 22 400 to 32 000 cells/mm(3)). Six weeks after stromal lamellar incision, keratocyte density was unchanged in the first countable frame of the anterior stroma, 43 700 cells/mm(3) (95% CI, 31 800 to 55 500 cells/mm(3); P = .29). There were no changes in cell density in deeper stromal regions. There was excellent agreement between ultrasonic and confocal microscopy measurements of corneal thickness. In vivo repeatability of keratocyte density estimation using scanning laser confocal microscopy is comparable with the results of previous reports using tandem-scanning confocal microscopy. Keratocyte density was more varied, but not significantly different, in the anterior-most corneal stroma 6 weeks after a lamellar incision. Copyright © 2011 Elsevier Inc. All rights reserved.
Hayes, Sally; Kamma-Lorger, Christina S.; Boote, Craig; Young, Robert D.; Quantock, Andrew J.; Rost, Anika; Khatib, Yasmeen; Harris, Jonathan; Yagi, Naoto; Terrill, Nicholas; Meek, Keith M.
Purpose To examine the effect of riboflavin/UVA corneal crosslinking on stromal ultrastructure and hydrodynamic behaviour. Methods One hundred and seventeen enucleated ungulate eyes (112 pig and 5 sheep) and 3 pairs of rabbit eyes, with corneal epithelium removed, were divided into four treatment groups: Group 1 (28 pig, 2 sheep and 3 rabbits) were untreated; Group 2 (24 pig) were exposed to UVA light (3.04 mW/cm2) for 30 minutes and Group 3 (29 pig) and Group 4 (31 pig, 3 sheep and 3 rabbits) had riboflavin eye drops applied to the corneal surface every 5 minutes for 35 minutes. Five minutes after the initial riboflavin instillation, the corneas in Group 4 experienced a 30 minute exposure to UVA light (3.04 mW/cm2). X-ray scattering was used to obtain measurements of collagen interfibrillar spacing, spatial order, fibril diameter, D-periodicity and intermolecular spacing throughout the whole tissue thickness and as a function of tissue depth in the treated and untreated corneas. The effect of each treatment on the hydrodynamic behaviour of the cornea (its ability to swell in saline solution) and its resistance to enzymatic digestion were assessed using in vitro laboratory techniques. Results Corneal thickness decreased significantly following riboflavin application (p<0.01) and also to a lesser extent after UVA exposure (p<0.05). With the exception of the spatial order factor, which was higher in Group 4 than Group 1 (p<0.01), all other measured collagen parameters were unaltered by cross-linking, even within the most anterior 300 microns of the cornea. The cross-linking treatment had no effect on the hydrodynamic behaviour of the cornea but did cause a significant increase in its resistance to enzymatic digestion. Conclusions It seems likely that cross-links formed during riboflavin/UVA therapy occur predominantly at the collagen fibril surface and in the protein network surrounding the collagen. PMID:23349690
Hayes, Sally; Kamma-Lorger, Christina S; Boote, Craig; Young, Robert D; Quantock, Andrew J; Rost, Anika; Khatib, Yasmeen; Harris, Jonathan; Yagi, Naoto; Terrill, Nicholas; Meek, Keith M
To examine the effect of riboflavin/UVA corneal crosslinking on stromal ultrastructure and hydrodynamic behaviour. One hundred and seventeen enucleated ungulate eyes (112 pig and 5 sheep) and 3 pairs of rabbit eyes, with corneal epithelium removed, were divided into four treatment groups: Group 1 (28 pig, 2 sheep and 3 rabbits) were untreated; Group 2 (24 pig) were exposed to UVA light (3.04 mW/cm(2)) for 30 minutes and Group 3 (29 pig) and Group 4 (31 pig, 3 sheep and 3 rabbits) had riboflavin eye drops applied to the corneal surface every 5 minutes for 35 minutes. Five minutes after the initial riboflavin instillation, the corneas in Group 4 experienced a 30 minute exposure to UVA light (3.04 mW/cm(2)). X-ray scattering was used to obtain measurements of collagen interfibrillar spacing, spatial order, fibril diameter, D-periodicity and intermolecular spacing throughout the whole tissue thickness and as a function of tissue depth in the treated and untreated corneas. The effect of each treatment on the hydrodynamic behaviour of the cornea (its ability to swell in saline solution) and its resistance to enzymatic digestion were assessed using in vitro laboratory techniques. Corneal thickness decreased significantly following riboflavin application (p<0.01) and also to a lesser extent after UVA exposure (p<0.05). With the exception of the spatial order factor, which was higher in Group 4 than Group 1 (p<0.01), all other measured collagen parameters were unaltered by cross-linking, even within the most anterior 300 microns of the cornea. The cross-linking treatment had no effect on the hydrodynamic behaviour of the cornea but did cause a significant increase in its resistance to enzymatic digestion. It seems likely that cross-links formed during riboflavin/UVA therapy occur predominantly at the collagen fibril surface and in the protein network surrounding the collagen.
Rezaei Kanavi, Mozhgan; Tabeie, Faraj; Sahebjam, Farzin; Poursani, Nima; Jahanbakhsh, Nazanin; Paymanpour, Pouya; AfsarAski, Sasha
This study was conducted to investigate the effect of combining extremely low frequency-pulsed electromagnetic field (ELF-PEMF) and low-level laser therapy (LLLT) on alkali-burned rabbit corneas. Fifty alkali-burned corneas of 50 rabbits were categorized into five groups: ELF-PEMF therapy with 2 mT intensity (ELF 2) for 2 h daily; LLLT for 30 min twice daily; combined ELF-PEMF and LLLT (ELF + LLLT); medical therapy (MT); and control (i.e., no treatment). Clinical examination and digital photography of the corneas were performed on days 0, 2, 7, and 14. After euthanizing the rabbits, the affected eyes were evaluated by histopathology. The clinical and histopathologic results were compared between the groups. On days 7 and 14, no significant difference in the corneal defect area was evident between the ELF, LLLT, ELF + LLLT, and MT groups. Excluding the controls, none of the study groups demonstrated a significant corneal neovascularization in both routine histopathology and immunohistochemistry for CD31. Keratocyte loss was significantly higher in the MT group than in the ELF, LLLT, and ELF + LLLT groups. Moderate to severe stromal inflammation in the LLLT group was comparable with that in the MT group and was significantly lower than that in the other groups. In conclusion, combining LLLT and ELF was not superior to ELF alone or LLLT alone in healing corneal alkali burns. However, given the lower intensity of corneal inflammation and the lower rate of keratocytes loss with LLLT, this treatment may be superior to other proposed treatment modalities for healing alkali-burned corneas. Copyright © 2016 Elsevier Ltd. All rights reserved.
Karla, Pradeep K.; Pal, Dhananjay; Quinn, Tim; Mitra, Ashim K.
Cornea is considered as a major barrier for ocular drug delivery. Low ocular bioavailability of drugs has been attributed primarily to low permeability across corneal epithelium thus leading to sub-therapeutic concentrations of drug in the eye and treatment failure. The role of drug efflux proteins, particularly the Pglycoprotein in ocular drug bioavailability has been reported. The objective of this research was to determine whether human corneal epithelium expresses multi drug resistance associated proteins contributing to drug efflux by employing both cultured corneal cells and freshly excised rabbit cornea. SV40 HCEC and rPCEC were selected for in-vitro testing. SV40-HCEC and freshly excised rabbit corneas were utilized for transport studies. [3H]-cyclosporine-A and [14C]-erythromycin which are known substrates for ABCC2 and MK-571, a specific inhibitor for MRP were applied in this study. RT-PCR indicated a unique and distinct band at ∼272 bp corresponding to ABCC2 in HCEC, SV40-HCEC, rabbit cornea, rPCEC and MDCKII-MRP2 cells. Also RT-PCR indicated a unique band ∼181 bp for HCEC and SV40-HCEC. Immunoprecipitation followed by Western Blot analysis revealed a specific band at ∼190-kDa in membrane fraction of SV40-HCEC, MDCKII-MRP2 and no band with isotype control. Uptake of [3H]-cyclosporine-A and [14C]-erythromycin in the presence of MK-571 was significantly enhanced than control in both SV40 HCEC and rPCEC. Similarly a significant elevation in (A→B) permeability of [3H]-cyclosporine-A and [14C]-erythromycin was observed in the presence of MK-571 in SV40-HCEC. A→B transport of [3H]-cyclosporine-A was elevated in the presence of MK-571 in freshly excised rabbit cornea indicating potential role of this efflux transporter and high clinical significance of this finding. PMID:17156953
Farid, Marjan; Morishige, Naoyuki; Lam, Larry; Wahlert, Andrew; Steinert, Roger F.; Jester, James V.
Purpose Recent studies have shown that confocal imaging of second harmonic–generated (SHG) signals can detect corneal collagen organization. The purpose of this study was to assess whether SHG signals can detect differences in corneal fibrosis after excimer laser surface ablation (photorefractive keratectomy [PRK]). Methods Rabbits received 9-D PRK in one eye followed by treatment with either mitomycin C (MMC) or vehicle. Corneal haze was measured by in vivo confocal microscopy before and 2, 4, 8, and 12 weeks after surgery. Animals were then killed and corneas were evaluated by visible and nonlinear confocal microscopy. Results PRK induced significant haze in vehicle-treated corneas that peaked at 2 weeks and remained elevated at 12 weeks after surgery. MMC treatment significantly (P = 0.05) reduced corneal haze at 2 weeks and was essentially normal by 12 weeks. Imaging of SHG signals in vehicle-treated eyes showed an anterior layer of collagen forming a honeycomb network blending into a dense mat of irregularly arranged collagen fibers that overlaid normal orthogonally arranged collagen lamellae. MMC treatment showed normal collagen organization at the surface. Fibrotic tissue was associated with a high cell density and alignment of intracellular actin filaments with collagen fiber bundles. In MMC-treated eyes, an anterior acellular zone overlaid a sparsely populated stroma containing isolated and enlarged keratocytes. Conclusions Imaging of SHG signals provides a sensitive means for detection of corneal fibrosis after surface ablation and can be used to assess the effects of antifibrotic therapy on corneal healing after refractive surgery. PMID:18502995
Wollensak, Gregor; Iomdina, Elena; Dittert, Dag-Daniel; Herbst, Hermann
This study was undertaken to investigate the wound healing process of the first 6 weeks after photodynamic cross-linking treatment in the rabbit cornea, using the photosensitizer riboflavin and UVA. After removal of the central epithelium, the right corneas of 8 Chinchilla rabbits were cross-linked with a photosensitizing 0.1% riboflavin solution and UVA light (370 nm; irradiance, 3 mW/cm(2); dose, 5.4 J/cm(2)) for 30 minutes. Two animals were euthanized 3 days, 7 days, 4 weeks, and 6 weeks postoperatively. The corneas of the enucleated eyes were evaluated using 4-microm light microscopic sections with routine stains and avidin-biotin complex immunostaining with anti-alpha-smooth muscle actin. By day 3 after treatment, complete apoptotic damage and loss of the endothelial cells and the stromal keratocytes were found in the irradiated area through the entire thickness of the stroma. There was marked stromal edema (850 +/- 66 vs. 332 +/- 43 microm in the untreated controls; P < 0.01). The epithelium was already closed again. At the margins of the lesion, there was a mild inflammatory reaction with scattered macrophages, lymphocytes, and neutrophils. By day 7, the endothelium was already intact again, and keratocyte repopulation of the posterior stroma was noted. By week 4, the keratocyte repopulation of the anterior stroma was observed with some acellular areas between. By week 6, the cytoarchitecture of the cornea seemed normal again. By weeks 4 and 6, alpha-actin-positive keratocytes were identified, especially in the periphery of the irradiated area. After riboflavin/UVA cross-linking of rabbit cornea, a complete cell loss occurs in the irradiation area with an irradiance of 3 mW/cm(2). The cytotoxic damage is repaired by repopulation after approximately 4-6 weeks. A combination of cross-linking with other procedures such as the implantation of intracorneal rings should be performed only after a sufficient time interval of approximately 2 months, allowing cellular
Liang, H; Baudouin, C; Pauly, A; Brignole-Baudouin, F
Aim: To compare the conjunctival and corneal reactions of commercially available solution of latanoprost (Xalatan) and preservative-free (PF) tafluprost in rabbits. Methods: The rabbits received 50 μl of phosphate-buffered saline (PBS), PF-tafluprost 0.0015%, latanoprost 0.005% or benzalkonium chloride (BAK) 0.02%; all solutions were applied at 5 min intervals for a total of 15 times. The ocular surface toxicity was investigated using slit-lamp biomicroscopy examination, flow cytometry (FCM) and on imprints for CD45 and tumour necrosis factor-receptor 1 (TNFR1) conjunctival impression cytology (CIC) and corneal in vivo confocal microscopy (IVCM). Standard immunohistology also assessed inflammatory/apoptotic cells. Results: Clinical observation and IVCM images showed the highest ocular surface toxicity with latanoprost and BAK, while PF-tafluprost and PBS eyes presented almost normal corneoconjunctival aspects. FCM showed a higher expression of CD45+ and TNFR1+ in latanoprost- or BAK-instilled groups, compared with PF-tafluprost and PBS groups. Latanoprost induced fewer positive cells for inflammatory marker expressions in CIC specimens compared with BAK-alone, both of which were higher than with PF-tafluprost or PBS. Immunohistology showed the same tendency of toxic ranking. Conclusion: The authors confirm that rabbit corneoconjunctival surfaces presented a better tolerance when treated with PF-tafluprost compared with commercially available latanoprost or BAK solution. PMID:18723745
Chesnokova, N B; Beznos, O V; Pavlenko, T A; Zabozlaev, A A; Pavlova, M V
Deepithelialization of the cornea (diameter 7 mm) was performed in rabbits and the rate of defect epithelialization was evaluated. Conjunctival ischemia was modeled by application of graduated alkaline burn. Antioxidant activity and content of nitrates and nitrites was measured in the tear fluid before and after burn by chemiluminescence and Griess methods, respectively. Emoxypin and mexidol promoted healing of corneal epithelial defect at the stage of epitheliocyte migration to the defect area and at the stage of their proliferation, respectively. After treatment with both agents, the area of conjunctival ischemia decreased more rapidly, but the efficiency of mexidol was higher. Antioxidant activity and content of products of NO metabolism in tear fluid decreased after burn. Mexidol, but not emoxypin, increased these parameters. Thus, mexidol and emoxypin have different effects on corneal epithelialization and conjunctival ischemia and effects of mexidol are more pronounced.
Gray, Brad; Binder, Perry S; Huang, Ling C; Hill, Jim; Salvador-Silva, Mercedes; Gwon, Arlene
To compare morphologic differences between freehand diamond or femtosecond laser-assisted penetrating and intrastromal arcuate incisions. Freehand diamond blade, corneal arcuate incisions (180° apart, 60° arc lengths) and 150 kHz femtosecond laser (80% scheimpflug pachymetry depth corneal thickness) arcuate incisions were performed in rabbits. Intrastromal arcuate incisions (100 μm above Descemet's membrane, 100 μm below epithelium) were performed in rabbit corneas (energy 1.2 μJ, spot line separation 3 × 3 μm, 90° side cut angle). Eyes were examined by slit lamp and light microscopy up to 47 days post-procedure. Freehand diamond blade penetrating incisions, and femtosecond laser penetrating and intrastromal arcuate incisions (energy 1.8 μJ, spot line separation 2 × 2 μm) were performed in cadaver eyes. Optical coherence tomography was performed immediately after surgery and the corneas were fixed for light scanning and transmission electron microscopy. The rabbit model showed anterior stromal inflammation with epithelial hyperplasia in penetrating blade and laser penetrating wounds. The laser intrastromal and penetrating incisions showed localized constriction of the stromal layers of the cornea near the wound. In cadaver eyes, penetrating wound morphology was similar between blade and laser whereas intrastromal wounds did not affect the cornea above or below incisions. Penetrating femtosecond laser arcuate incisions have more predictable and controlled outcomes shown by less post-operative scarring than incisions performed with a diamond blade. Intrastromal incisions do not affect uncut corneal layers as demonstrated by histopathology. The femtosecond laser has significant advantages in its ability to make intrastromal incisions which are not achievable by traditional freehand or mechanical diamond blades.
Lea, P.J.; Hollenberg, M.J.; Menon, I.A.; Temkin, R.J.; Persad, S.D.; Basu, P.K. )
The ultrastructure of rabbit cornea endothelial cells was examined by scanning electron microscopy (SEM) in freeze-cleaved corneas using a Hitachi S-570 scanning electron microscope in the high resolution mode (HRSEM). In order to study phototoxic effects in vitro, rabbit corneas (experimental) were cultured as organ culture in the presence of 5 micrograms/ml chlorpromazine (CPZ) and irradiated. For comparison, control 1 corneas were not irradiated but incubated in the dark without CPZ in the medium; control 2 corneas were also kept in the dark but in the presence of CPZ; control 3 corneas were irradiated with no CPZ in the medium. Cellular damage was not seen in the three types of control corneas, but in the experimental corneas the endothelial cells showed extensive disruption of the cell membrane and some deterioration of the intracellular components. Our study confirmed that HRSEM is a satisfactory new technique for visualizing damage of the intracellular organelles of corneal endothelium.
Hutak, Christine M; Kavanagh, Marie E; Reddy, Indra K
Statens Seruminstitut Rabbit Cornea (SIRC) cells were grown on sterile polycarbonate- and polyester-based filter inserts to evaluate the feasibility of substituting the polyester-based filter inserts for use in a previously developed permeability model. The two filter types were compared for differences in cellular growth rate and morphological changes following days 3, 7 and 10 in culture. There were no significant differences in the number of cell layers formed on any day examined. The numbers of cell layers formed with the polycarbonate-based filter inserts were 1.75 +/- 0.09, 2.53 +/- 0.14 and 2.93 +/- 0.16, for days 3, 7 and 10, respectively. The numbers of cell layers formed with the polyester-based filter inserts were 1.79 +/- 0.07, 2.23 +/- 0.11 and 2.90 +/- 0.13, for days 3, 7 and 10, respectively. The SIRC cells had a similar comparative morphology on each of the above days. Active cell growth was seen on each day with signs of maturation evident by day 7 in culture. The polyester-based filter inserts can be substituted in the previously established permeability assay without alteration of morphology or rate of growth, thus allowing confirmation of cell confluency prior to use in the permeability assay. It will also allow for photographic documentation of cell injury prior to recovery studies, without necessitating the preparation of extra samples for fixation at the time of initial injury. Future studies will be required to determine if there will be any alteration in the rate of permeability with a previously tested standard, before adoption of the new filter. Copyright 2002 S. Karger AG, Basel
Cham, Gregory; Pan, James Chuan-Hsin; Lim, Francis; Earnest, Arul; Gopalakrishnakone, P
The Naja sumatrana cobra can spit venom in defense and may result in permanent blindness. The study sought to determine the efficacy of topical heparin, Haffkine antivenom, tetracycline and dexamethasone. Male New Zealand White Rabbits were used. Pooled venom was frozen at -30 degrees C. 0.05 mL of 20 times dilute venom was introduced into the conjunctiva, in groups of three rabbits randomly. Heparin at 5000 IU/mL, Haffkine antivenom or saline control was administered repeatedly on each rabbit's eye over 158 minutes, after a specified delay. In other groups, 1% tetracycline, 0.1% dexamethasone or a placebo ointment was applied and repeated at 24 and 48 hours. All the rabbits were assessed after 24, 48, 72 hours, one and two weeks by an ophthalmologist blinded to the treatment arms. Following ocular envenomation, there was immediate blepharospasm, lacrimal secretions, redness and chemosis; more intense in the normal saline group. The Roper-Hall grades improved, corneas re-epithelialized and inflammation quietened in the heparin and antivenom-treated rabbit eyes compared to controls. Scarring appeared from the first week, but ameliorated in the heparin and antivenom groups. Heparin treatment remained efficacious up to four minutes delay. The tetracycline, dexamethasone and placebo groups had worsening Roper-Hall trends, greater corneal epithelial loss, inflammation and scarring. Combined heparin-tetracycline therapy was as efficacious with heparin alone. Topical heparin or antivenom therapy significantly improved overall outcomes in rabbit corneas exposed to Naja sumatrana venom, compared to tetracycline, dexamethasone and controls. Heparin treatment remains efficacious up to 4 minutes delay.
Hsiue, G H; Lee, S D; Wang, C C; Shiue, M H; Chang, P C
A poly(2-hydroxyethyl methacrylate) (pHEMA)-grafted polymer film was prepared by plasma-induced graft copolymerization onto an elastic material, silicone rubber, and a plastic material, poly(4-methyl-1-pentene) (TPX). The control, Ar plasma-treated and pHEMA-grafted silicone rubber and TPX surfaces were characterized by ESCA, FTIR-ATR, SEM and contact angle techniques. ESCA verified the respective chemical shift of control and Ar plasma-treated films. The presence of the grafted pHEMA was also verified by ESCA. The introduction of pHEMA onto a hydrophobic support provided an adequate surface for rabbit corneal epithelium cell attachment and growth. Cell attachment and growth onto these surfaces were examined by light microscopy. Cell attachment onto the control and Ar plasma-treated surfaces was negligible, while improved attachment and growth of rabbit corneal epithelium cells was demonstrated on the pHEMA-grafted polymeric surface. At 72 h, the pHEMA-grafted silicone rubber surface attached and grew more cells as compared with those on a pHEMA-grafted TPX surface. The pHEMA-grafted silicone rubber surface demonstrated a confluent cell layer after 72 h.
Can Riboflavin Penetrate Stroma Without Disrupting Integrity of Corneal Epithelium in Rabbits? Iontophoresis and Ultraperformance Liquid Chromatography With Electrospray Ionization Tandem Mass Spectrometry.
Novruzlu, Şahin; Türkcü, Ümmühani Özel; Kvrak, İbrahim; Kvrak, Şeyda; Yüksel, Erdem; Deniz, Nuriye Gökçen; Bilgihan, Ayşe; Bilgihan, Kamil
To examine riboflavin concentrations in corneas and aqueous humor from rabbits with standard and transepithelial methods and iontophoresis without disrupting the integrity of the corneal epithelium before corneal collagen cross-linking. Twenty-four eyes of 12 adult New Zealand rabbits were used. They were assigned to 4 groups, each including 6 eyes. Group 1 was exposed to the standard method and given riboflavin 0.1% after epithelial debridement. Group 2 was exposed to the transepithelial method and given benzalkonium chloride (BAC), ethylenediaminetetraacetic acid (EDTA), trometamol (TRIS), hydroxypropylmethylcellulose (HPMC), and riboflavin 0.2% 3 times at 1.5-minute intervals followed by riboflavin 0.2%. Group 3 was given riboflavin 0.1% by using 1-mA electric current for 10 minutes with the help of iontophoresis without using substances disrupting the integrity of the corneal epithelium. Group 4 received the same treatment as did group 3, except that it was given riboflavin 0.2%. Following these treatments, riboflavin concentrations in aqueous humor and corneas were measured with ultraperformance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). Riboflavin concentrations in the cornea and aqueous humor were higher in group 1 (42.4 ± 5.4 μg/g) than in the other groups. They were significantly higher in group 4 (34.2 ± 6.6 μg/g) than in group 2 (24.4 ± 1.2 μg/g) (P = 0.009) and group 3 (23.6 ± 6.1 μg/g) (P = 0.026). There was not a significant difference in corneal riboflavin concentrations between group 2 and group 3 (P = 0.937). Intrastromal and aqueous riboflavin concentrations after administration of riboflavin 0.2% through iontophoresis without disrupting the integrity of the corneal epithelium were lower than those after the standard method, but higher than those after the transepithelial method. In this study, in which riboflavin concentrations were measured with a very sensitive method
Diao, Yu-Mei; Hong, Jing
Human corneal endothelial cells are a non-proliferative cell type. As a result of the increase in corneal endothelium disease, increasing numbers of studies have been conducted in order to promote corneal endothelial cell proliferation. The aim of the present study was to investigate the proliferative effects of Rho-associated protein kinase inhibitor, Y-27632, on rabbit corneal endothelial cells (rCECs). Y-27632 (1, 10 or 30 μM) was added at two different time points to two groups of rCECs. The first group received Y-27632 when rCECs were initially plated, and the second following 72 h of cell growth. Cell morphology and cell adhesion ratios were subsequently observed using light microscopy. A cell counting kit was used to measure the number of viable cells that adhered to culture plates. Cell cycle transitions and levels of Annexin V-positive apoptotic cells were detected using flow cytometry. Cells treated with 1 μM Y-27632 and 10 μM Y-27632 retained their cell shape. At a concentration of 30 μM Y-27632, the cell shape became irregular. Cell adhesion ratios, in 1 μM Y-27632 (36.84%), 10 μM Y-27632 (84.21%) and 30 μM Y-27632 (84.21%) were higher than the adhesion ratio in the control group (P<0.01). The optical densities of rCECs treated with 10 μM or 30 μM Y-27632 following 72 h of cell growth was less than that of the control cells (P<0.01), but higher than that of cells which received Y-27632 at the time of plating (P<0.01). Flow cytometry results also demonstrated that there was a delay in G1 to S phase cell cycle progression in rCECs following administration of 10 μM Y-27632 (P<0.01). Cell apoptosis was inhibited when 10 μM Y-27632 was added, at the time of cell plating, as well as when added following 72 h of cell growth (P<0.01). At a concentration of 10 μM Y-27632, there was an improvement in cell adhesion and an inhibition of the cell cycle in rabbit corneal endothelial cells. In conclusion, Y-27632 has different effects on rCECs when
Kawazu, K; Yamada, K; Nakamura, M; Ota, A
The purpose of this study was to characterize cyclosporin A (CsA) uptake and transport in cultured rabbit corneal epithelial cells (RCECs). CsA uptake was evaluated by measuring time-dependent 3H-CsA accumulation in confluent RCECs. Bidirectional 3H-CsA fluxes were measured across the RCEC layers grown on Transwell-COL culture plate inserts. The anti-P-gp monoclonal antibody C219 was used in western blot analysis to probe for the presence of P-gp in these cells. The accumulation of 3H-CsA was time and temperature dependent. Steady state was reached by 60 minutes. The initial uptake was saturable and was suppressed as a function of increases in preloading with unlabeled CsA. This uptake process was enhanced by metabolic inhibition with either 3-O-methylglucose, MG, or 10 mM NaN3 and 3-O-MG. The largest increase was obtained with 10 mM NaN3 in combination with 3-O-MG. In their presence, uptake increased by 40%. A multidrug-resistance (MDR)-reversing agent (i.e., 500 microM verapamil, 100 microM vincristine, 100 microM progesterone, 100 microM testosterone, 500 microM quinidine, or 100 microM chlorpromazine) significantly increased 3H-CsA accumulation. The largest increase was obtained with 500 microM quinidine (i.e., 36%). Conversely, verapamil and vincristine produced the largest inhibition of 3H-CsA efflux (i.e., 19% and 28%, respectively). However, in the presence of 10 microM unlabeled CsA, 3H-CsA efflux increased. 3H-CsA flux across RCEC layers showed marked directional asymmetry. The stromal (S) to tear (T) side transcellular 3H-CsA permeability coefficient (Ptrans) was approximately seven times higher than that in the T-to-S direction. The S-to-T Ptrans was reduced by an MDR-reversing agent by up to 40%. Western blot analysis of lysates revealed a 170-kDa membrane protein band. These results suggest that in RCEC the tear-side-facing membrane has a P-gp-mediated drug efflux pump. In addition, there is suggestive evidence for the presence of the cytosolic
Jiang, Wei; Sun, Hui-Min; Li, Xiao-Rong; Yuan, Xu-Bo; Wang, Yu-Qing; Zhang, Shu-Xian; Tian, En-Jiang; Yuan, Jia-Qin
To evaluate the combined effect of topical rapamycin (RAPA) eye drop in nanometer vector and poly (lactic acid) (PLA) wafers of cyclosporine A (CsA) in the prevention of acute allograft rejection after rabbit corneal transplantation. Methods It was an experimental study. RAPA was incorporated into the nanometer particles and CsA was incorporated into PLA wafers. A was syngeneic control whose both donor and recipient are New Zealand rabbit. Gray donor corneas were implanted into the 102 recipients of New Zealand albino rabbits with corneal neovascularization who were randomly divided into B, C, D, E, F, G 6 groups to receive the different types of therapy: B was no therapy control; C was eye drop of nanometer vector but no RAPA twice a day, 28 days; D was PLA wafers in the anterior chamber of rabbit eyes but no drugs; E was 0.5% RAPA eye drop of nanometer vector twice a day, 28 days; F was PLA wafers of CsA in the anterior chamber of rabbit eyes; G was PLA wafers of CsA in the anterior chamber of rabbit eyes and 0.5% RAPA eye drop of nanometer vector eye drop twice a day for 28 days together. Postoperative evaluation included slit-lamp biomicroscopy, histopathology and immunohistology, Cytokines related with neovascularization and immunosuppression in the corneal tissue by RT-PCR. The graft survival was assessed by One-Way ANOVA and q test. Corneal allograft survival time: A (100.00 +/- 0.00), B (8.44 +/- 1.24), C (8.89 +/- 2.57), D (8.56 +/- 2.30), E (43.11 +/- 5.58), F (43.67 +/- 9.54), G (72.00 +/- 15.34) d. Group G led to a statistically significant prolongation of transplant survival and was superior than group E and F which was a statistical prolongation compared with group B, C and D (qGE = 11.42, qGF = 11.24, qEB = 13.64, qEC = 13.38, qED = 13.46, qFB = 13.82, qFC = 13.56, qFD = 13.64; P < 0.01). Immunohistopathologically, the grafts were subjected to an immune response contained a dense infiltrate of neutrophils, CD4+ and CD8+ T lymphocytes in the group B
George, Eric M.; Mahdi, Fakhri; Logue, Omar C.; Robinson, Grant G.
Abstract Purpose: Elastin-like polypeptide (ELP) is a bioengineered protein widely applied as a drug carrier due to its biocompatibility and amenability to modification with cell-penetrating peptides (CPPs) and therapeutic agents. The purpose of this study was to determine whether topically applied ELP or CPP-fused ELPs penetrate the corneal barrier. Methods: In vitro binding and cytotoxicity to human corneal epithelial (HCE) cells were determined for ELP or CPP-ELPs. Corneal binding, clearance, and penetration were assessed in a rabbit model following topical application of the fluorescently labeled proteins by quantitative fluorescence imaging and histology. Results: ELP bound to HCE cells in vitro, and binding/uptake was enhanced 2- to 3-fold by the addition of CPPs. When applied topically to rabbit eyes, ELP accumulated in the cornea at levels 7.4-fold higher than did an equivalent dose of immunoglobulin G. Both ELP and a CPP-ELP penetrated the corneal epithelium and were detectable in the stroma. Addition of CPPs to ELP, however, did not significantly enhance corneal uptake or penetration in vivo relative to ELP alone. The polypeptides cleared from the cornea over a period of 20–30 min after application, after which cornea levels reached a steady state of 15–30 μg/mL for up to 3 h. Conclusions: The ELP drug carrier can penetrate the corneal epithelium and accumulate in the stroma. Given its amenability for fusion to multiple types of therapeutic agents, ELP has the potential to serve as a drug carrier for topical ocular applications. PMID:26672799
Brody, D A; Mirvis, D M; Ideker, R E; Cox, J W; Keller, F W; Larsen, R A; Bandura, J P
We studied the relative dipolar and nondipolar content of signal energy throughout ventricular excitation and recovery in 34 isolated, perfused rabbit hearts, suspended in an electrolyte-filled spherical chamber. Computer-processed signals were derived from 20 evenly spaced tank-surface electrodes, and a single, moving, equivalent cardiac dipole generator was optimally fitted to the recorded potentials for each 1-msec sampling interval. Superimposed, time-based plots of signal energy for the 34 preparations showed ventricular excitation to be strikingly more nondipolar than was recovery. In terms of the summed square ratio of nondipolar residual energies, overall nondipolarity of QRS exceed that of ST-T by 41%. Furthermore, the maximum instantaneous ratio during QRS was considerably greater than during the ST-T. Evaluation of paired differences, comparing nondipolar behavior throughout QRS with all of ST-T, proved highly significant (P less than .005). We also found that in contrast to the considerable mobility exhibited by the equivalent QRS dipole, the ST-T dipole locus remained nearly stationary during most of ventricular recovery. Presumably because repolarization is temporally and spatially a relatively diffuse process, it may generate electrical fields which are notably more dipolar than those caused by depolarization.
Davies, Brett W; Panday, Vasudha; Caldwell, Matthew; Scribbick, Frank; Reilly, Charles D
To compare topical interleukin 1 receptor antagonist (IL-1ra) to steroid treatment following photorefractive keratectomy (PRK) in rabbit eyes. Our study is a randomized, investigator-masked study that was approved by the Institutional Animal Care and Use Committee. Following standard PRK, 48 eyes of 24 rabbits were divided into 5 arms: 4 treatment arms and 1 control arm. The right eye of each rabbit served as the treatment eye, and the left eye served as a control. Eyes in treatment arms were randomized to receive either fluorometholone, 0.1%, 4 times a day (Falcon, Fort Worth, Texas), or 2.5, 1.25, or 0.25 mg of IL-1ra 4 times a day. Control eyes received only moxifloxacin hydrochloride, 0.5% (Vigamox; Alcon, Fort Worth, Texas), and a solution of polyethylene glycol 400, 0.4%, and propylene glycol, 0.3% (Systane; Alcon), 4 times a day. Primary outcome measures included weekly evaluation of subjective haze formation and time to corneal reepithelization with clinic examinations, objective haze formation using Pentacam technology (Oculus, Lynnwood, Washington), as well as histological examination for haze thickness 7 weeks after PRK. There was no difference among treatment groups in time to reepithelization. The IL-1ra treatment groups showed a statistically significant reduction in haze formation (P < .001, determined by repeated-measures analysis of variance) on corneal evaluation using the Pentacam 3 weeks after PRK compared with the control group. This effect was comparable to that in the steroid treatment group. There was also a statistically significant effect of the treatment on subjective haze evaluation at weeks 4 and 5 (P < .05, determined by repeated-measures analysis of variance), but this effect lost statistical significance when the steroid group was excluded from the evaluation. In addition, there was no statistically significant difference in histologic evaluation of haze thickness among treatment groups (P = .997). Further studies are needed to
Shao, Yi; Tang, Jing; Zhou, Yueping; Qu, Yangluowa; He, Hui; Liu, Qiuping; Tan, Gang; Li, Wei; Liu, Zuguo
Our objective was to develop a novel lamellar cornealbiomaterial for corneal reconstruction.Theporcine acellular corneal stroma discs (ACSDs) were prepared from de-epithelized fresh porcine corneas (DFPCs) by incubation with 100% fresh human serum and additional electrophoresis at 4°C. Such manipulation removed theanterior corneal stromal cells without residual of DNA content and α-Galantigen. Human serum decellularizing activity on porcineanterior corneal stroma cells is through apoptosis, and associated with the presence of α-Gal epitopes in anterior stroma. ACSDs displayed similar optical, biomechanical properties and ultrastructure to DFPCs, and showed good histocompatibility in rabbit corneal stromal pockets and anterior chamber. Rabbit corneallamellar keratoplasty (LKP) using ACSDs showed no rejection and high transparency of cornea at 2 months after surgery. In vivo confocal laser scanning microscopy and immunostaining analysis showed complete re-epithelization and stromal cell in growth of ACSDs without inflammatory cell infiltration, new blood vessel ingrowth and excessive wound healing. In conclusion, this novel decellularization method may be valuable for preparation of xenogenic corneal tissue for clinical application, ACSDs resulted from this method may be served as a matrix equivalent for LKP in corneal xenotransplantation. PMID:26885261
van Bijsterveld, O P
Central corneal abscess developed in the experimental animal after inoculation of biologically active staphylococcal strains in a paracentral epithelial lesion of the cornea. These abscesses did not ulcerate, developed only with high inocula, occurred more frequently in immunized rabbits. A serpiginous type of ulceration did not develop at the site of the initial epithelial lesion nor at any other place in the cornea. Histologically, the lesions consisted of densely packed polymorphonuclear leukocytes between the corneal lamellae.
Phu, Donna; Orwin, Elizabeth J
The cornea is responsible for functional optical activity of the mammalian eye, as it must remain transparent in order to focus light onto the retina. Corneal disease is the second leading cause worldwide of vision loss . Human donor tissue transplantation in the cornea is associated with problems such as immunorejection and recurring graft failures . Tissue engineering offers a promising alternative to using human donor tissues in treating corneal diseases. A viable tissue-engineered cornea must be mechanically resilient to protect the fragile intraocular components of the eye, and optically transparent to refract light onto the retina. In the native cornea, transparency is maintained by both the cells in the stromal layer and the high organization of the extracellular matrix (ECM). This study aims to combine the effects of aligned collagen fibers and ascorbic acid derivatives to control corneal fibroblast behavior to not only express the appropriate proteins, but also to deposit aligned, small diameter collagen fibers that resemble the highly organized structure of the natural ECM. Results from this study suggest that the combined effect of an aligned scaffolding material and ascorbic acid supplements can create a cell-matrix construct that both downregulates expression of the light scattering protein a-smooth muscle actin (alpha-sma) and supports an increased number of cell layers.
Mota, Francisco Cláudio Dantas; Eurides, Duvaldo; Freitas, Patricia Maria Coletto; Beletti, Marcelo Emílio; Goulart, Michelle Rodriques; Cunha, Lívia Maria Ferreira; da Silva, Luiz Antonio Franco; Fioravanti, Maria Clorinda Soares
The aim of this study was to evaluate the cicatricial repair of perforating cornea in rabbits, by using the N-butyl cyanoacrylate adhesive compared to the 910-polyglactine thread suture through macroscopic and histological assays. Corneas from 18 adult rabbits were perforated and subsequently occluded with N-butyl cyanoacrylate synthetic adhesive (right cornea) or by separated single points using the 910-polyglactine thread (left cornea). The rabbits were divided into groups containing three animals per group. Examination after 7, 15, and 30 days post-operative showed that both the synthetic adhesive and the suture were efficient in the occlusion of the surgical wounds, thus stabilizing the intra-ocular content. The N-butyl cyanoacrylate adhesive was shown to be superior to the 910-polyglactine suture thread with regards to the evolution and the organization of the healing process.
Hwang, Ho Sik; Kim, Man Soo
To determine the effect of riboflavin/ultraviolet-A (365 nm) corneal collagen cross-linking on the transmission of the ultraviolet-visible (UV-VIS) light spectrum through the cornea. Twelve New Zealand white male rabbits were used in this research. Cross-linking was performed unilaterally on the right eyes of the animals while only the epithelium was removed on the left eyes as the control. Seven weeks after cross-linking, the animals were euthanized, and the enucleated eyes were processed for transmission spectroscopy. To confirm that the cross-linking procedures was done successfully on the right corneas, the tensile force-extension relationship was measured using six corneas from three of the rabbits after the transmission spectrum was determined. Seven weeks after cross-linking, ten of the 12 rabbits had clear corneas in the cross-linked and control eyes. The two rabbits with neovascularization and granular opacities in the right corneas were not included in subsequent measurements. In the cross-linked corneas, transmittance was 87.57% at 650 nm, and decreased continuously as the wavelength shortened. From 315 nm, the transmittance rapidly decreased and was 35.52% at 300 nm. In the control corneas, transmittance was 95.95% at 650 nm and decreased continuously as the wavelength shortened. Below 315 nm, the transmittance rapidly decreased, to 40.29% at 300 nm. The transmittance of the cross-linking corneas was 10%-20% lower than that of the control corneas. The difference was 8.38% at 650 nm and increased as the wavelength shortened, reaching a maximum of 20.59% at 320 nm, and decreased rapidly to 4.77% at 300 nm. The tensile force-extension relationship showed that a greater force was necessary to extend the cross-linking corneas over 500 µm than that of the control corneas. The transmittance of the cross-linked corneas was 10%-20% lower than that of the control corneas. The difference increased as the wavelength decrease, reaching a maximum at 320 nm and then
Hwang, Ho Sik
Purpose To determine the effect of riboflavin/ultraviolet-A (365 nm) corneal collagen cross-linking on the transmission of the ultraviolet-visible (UV-VIS) light spectrum through the cornea. Methods Twelve New Zealand white male rabbits were used in this research. Cross-linking was performed unilaterally on the right eyes of the animals while only the epithelium was removed on the left eyes as the control. Seven weeks after cross-linking, the animals were euthanized, and the enucleated eyes were processed for transmission spectroscopy. To confirm that the cross-linking procedures was done successfully on the right corneas, the tensile force-extension relationship was measured using six corneas from three of the rabbits after the transmission spectrum was determined. Results Seven weeks after cross-linking, ten of the 12 rabbits had clear corneas in the cross-linked and control eyes. The two rabbits with neovascularization and granular opacities in the right corneas were not included in subsequent measurements. In the cross-linked corneas, transmittance was 87.57% at 650 nm, and decreased continuously as the wavelength shortened. From 315 nm, the transmittance rapidly decreased and was 35.52% at 300 nm. In the control corneas, transmittance was 95.95% at 650 nm and decreased continuously as the wavelength shortened. Below 315 nm, the transmittance rapidly decreased, to 40.29% at 300 nm. The transmittance of the cross-linking corneas was 10%–20% lower than that of the control corneas. The difference was 8.38% at 650 nm and increased as the wavelength shortened, reaching a maximum of 20.59% at 320 nm, and decreased rapidly to 4.77% at 300 nm. The tensile force-extension relationship showed that a greater force was necessary to extend the cross-linking corneas over 500 µm than that of the control corneas. Conclusions The transmittance of the cross-linked corneas was 10%–20% lower than that of the control corneas. The difference increased as the wavelength decrease
... Injuries Dystrophies - conditions in which parts of the cornea lose clarity due to a buildup of cloudy material Treatments of corneal disorders include medicines, corneal transplantation, and corneal laser surgery. NIH: National Eye Institute
Pi, Liya; Chung, Pei-Yu; Sriram, Sriniwas; Rahman, Masmudur M; Song, Wen-Yuan; Scott, Edward W; Petersen, Bryon E; Schultz, Gregory S
To study the binding of connective tissue growth factor (CTGF) to cystine knot-containing ligands and how this impacts platelet-derived growth factor (PDGF)-B signaling. The binding strengths of CTGF to cystine knot-containing growth factors including vascular endothelial growth factor (VEGF)-A, PDGF-B, bone morphogenetic protein (BMP)-4, and transforming growth factor (TGF)-β1 were compared using the LexA-based yeast two-hybrid system. EYG48 reporter strain that carried a wild-type LEU2 gene under the control of LexA operators and a lacZ reporter plasmid (p80p-lacZ) containing eight high affinity LexA binding sites were used in the yeast two-hybrid analysis. Interactions between CTGF and the tested growth factors were evaluated based on growth of transformed yeast cells on selective media and colorimetric detection in a liquid β-galactosidase activity assay. Dissociation constants of CTGF to VEGF-A isoform 165 or PDGF-BB homo-dimer were measured in surface plasma resonance (SPR) analysis. CTGF regulation in PDGF-B presentation to the PDGF receptor β (PDGFRβ) was also quantitatively assessed by the SPR analysis. Combinational effects of CTGF protein and PDGF-BB on activation of PDGFRβ and downstream signaling molecules ERK1/2 and AKT were assessed in rabbit corneal fibroblast cells by Western analysis. In the LexA-based yeast two-hybrid system, cystine knot motifs of tested growth factors were fused to the activation domain of the transcriptional factor GAL4 while CTGF was fused to the DNA binding domain of the bacterial repressor protein LexA. Yeast co-transformants containing corresponding fusion proteins for CTGF and all four tested cystine knot motifs survived on selective medium containing galactose and raffinose but lacking histidine, tryptophan, and uracil. In liquid β-galactosidase assays, CTGF expressing cells that were co-transformed with the cystine knot of VEGF-A had the highest activity, at 29.88 ± 0.91 fold above controls (P < 0.01). Cells
Chen, Junzhao; Shao, Chunyi; Lu, Wenjuan; Yan, Chenxi; Yao, Qinke; Zhu, Mengyu; Chen, Ping; Gu, Ping; Fu, Yao; Fan, Xianqun
To investigate the effect of the ATP-P2Y2-PI3K/Akt signaling axis on promoting rabbit corneal endothelial cell (RCEC) proliferation in vitro. Five concentrations of adenosine triphosphate (ATP; 1, 10, 25, 50 and 100 μM) were added to RCECs, and the cell proliferation was detected using Cell Counting Kit-8 (CCK8) and Ki67 immunohistochemical staining. Other P2Y2 receptor agonists and antagonists were added to the cells, and the proliferation effect was evaluated using CCK8 to determine the involvement of the P2Y2 receptor. Changes in the expression of phosphorylated Akt in RCECs treated with different concentrations of extracellular ATP and the duration of extracellular ATP on Akt phosphorylation were investigated using Western blotting. The pharmacological profiles with or without the PI3K/Akt pathway inhibitors were also determined using Western blotting. We found that 10 μM ATP strongly promoted RCEC proliferation in vitro. Additionally, 25 μM ATP had a proliferation effect, whereas other concentrations (1, 50 and 100 μM) had no effect compared with the control group. Selective P2Y2 receptor agonists (UTP, ATPγS and Ap4A) showed the same promotion effect, while P2Y2 antagonists and PI3K/Akt inhibitors inhibited the effect of ATP. Moreover, phosphorylated Akt could be induced by the addition of extracellular ATP at all five concentrations and lasted for 1 h. This phosphorylation was prevented by PI3K/Akt inhibitors and a P2Y2 antagonist. These findings showed that 10 μM ATP markedly promoted RCEC proliferation via the P2Y2-PI3K/Akt signaling axis. © 2014 S. Karger AG, Basel.
data in the literature. 15. SUBJECT TERMS corneal organotypic culture, laser, threshold, thermography , Probit 16. SECURITY CLASSIFICATION OF...literature. Keywords: corneal organotypic culture, laser, threshold, thermography , Probit 1. INTRODUCTION Use of lasers has become commonplace...temperature increases from exposure to the 2-µm laser were measured using the IR camera during laser exposure to membranes that were dry , wetted from
Lima, Tiago Barbalho; Ribeiro, Alexandre Pinto; Conceição, Luciano Fernandes da; Bandarra, Marcio; Manrique, Wilson Gomez; Laus, José Luiz
To assess the effects of 0.5% ketorolac tromethamine without preservatives on the expression of iNOS and MMP-9 in alkali burn ulcers. Twelve eyes of 120-day-old male rabbits were treated (TG) every 6 h with 0.5% ketorolac tromethamine and 12 other eyes were treated with saline solution (CG), immediately after the occurrence of ulcers by 1 M sodium hydroxide (NaOH). Re-epithelialization was monitored using fluorescein every 6 h. After 24 h, six corneas (n=6) of each group were collected (M1). The others (n=6) were collected after reepithelialization (M2). At both moments, the inflammatory infiltrate and the conditions of the newly formed epithelium were histologically analyzed. iNOS and MMP-9 were evaluated by immunohistochemistry. Mean epithelialization time in TG was 55 ± 0.84 h. In CG, it was 44 ± 1.06 h (p=0.001). At M1, corneas of TG had lower inflammatory exudation compared with (p <0.001). At M2, TG revealed discrete inflammatory exudation (p>0.05) and lower numbers of epithelial layers compared with CG. The mean iNOS in stromal cells did not differ in TG over both moments compared with CG (p>0.05) At M2, the central corneal region expressed more iNOS in both groups compared with the peripheral region. No significant differences were observed in iNOS scores of epithelial immunostaining between the groups and across M1 and M2 (p=0.69). Epithelial immunostaining scores for MMP-9 did not differ in TG compared with CG (p=0.69). The average immunostaining score of MMP-9 in stromal cells showed no differences between groups or moments. There was no correlation between immunostaining of iNOS and MMP-9 or between the amount of inflammatory cells and immunostaining of iNOS. Use of 0.5% keratolac tromethamine reduced inflammation and delayed reepithelialization in a cornea alkali burn model without impacting the expression of iNOS or MMP-9.
Alaminos, Miguel; Del Carmen Sánchez-Quevedo, María; Muñoz-Avila, José Ignacio; Serrano, Daniel; Medialdea, Santiago; Carreras, Ignacio; Campos, Antonio
To construct a full-thickness biological substitute of the rabbit cornea by tissue engineering. Ten rabbit corneas were surgically excised, and the three main cell types of the cornea (epithelial, stromal, and endothelial cells) were cultured. Genetic profiling of the cultured cells was performed by RT-PCR for the genes COL8 and KRT12. To develop an organotypic rabbit cornea equivalent, we used a sequential culture technique on porous culture inserts. First, endothelial cells were seeded on the base of the inserts. Then, a stroma substitute made of cultured keratocytes entrapped in a gel of human fibrin and 0.1% agarose was developed. Finally, cultured corneal epithelial cells were grown on the surface of the scaffold. Stratification of the epithelial cell layer was promoted by using an air-liquid culture technique. Corneal substitutes were analyzed by light and electron microscopy. All three types of corneal cells were efficiently cultured in the laboratory, expanded, and used to construct a full-thickness cornea substitute. Gene expression analyses confirmed that cultured endothelial cells expressed the COL8 gene, whereas epithelial cells expressed KRT12. Microscopic evaluation of the cornea substitutes demonstrated that epithelial cells tended to form a normal stratified layer and that stromal keratocytes proliferated rapidly in the stromal substitute. The endothelial monolayer exhibited a pattern similar to a normal corneal endothelium. These findings suggest that development of a full-thickness rabbit cornea model is possible in the laboratory and may open new avenues for research.
Klintworth, Gordon K
The term corneal dystrophy embraces a heterogenous group of bilateral genetically determined non-inflammatory corneal diseases that are restricted to the cornea. The designation is imprecise but remains in vogue because of its clinical value. Clinically, the corneal dystrophies can be divided into three groups based on the sole or predominant anatomical location of the abnormalities. Some affect primarily the corneal epithelium and its basement membrane or Bowman layer and the superficial corneal stroma (anterior corneal dystrophies), the corneal stroma (stromal corneal dystrophies), or Descemet membrane and the corneal endothelium (posterior corneal dystrophies). Most corneal dystrophies have no systemic manifestations and present with variable shaped corneal opacities in a clear or cloudy cornea and they affect visual acuity to different degrees. Corneal dystrophies may have a simple autosomal dominant, autosomal recessive or X-linked recessive Mendelian mode of inheritance. Different corneal dystrophies are caused by mutations in the CHST6, KRT3, KRT12, PIP5K3, SLC4A11, TACSTD2, TGFBI, and UBIAD1 genes. Knowledge about the responsible genetic mutations responsible for these disorders has led to a better understanding of their basic defect and to molecular tests for their precise diagnosis. Genes for other corneal dystrophies have been mapped to specific chromosomal loci, but have not yet been identified. As clinical manifestations widely vary with the different entities, corneal dystrophies should be suspected when corneal transparency is lost or corneal opacities occur spontaneously, particularly in both corneas, and especially in the presence of a positive family history or in the offspring of consanguineous parents. Main differential diagnoses include various causes of monoclonal gammopathy, lecithin-cholesterol-acyltransferase deficiency, Fabry disease, cystinosis, tyrosine transaminase deficiency, systemic lysosomal storage diseases (mucopolysaccharidoses
Belknap, Ellen B
Corneal emergencies can be due to a number of different causes and may be vision threatening if left untreated. In an attempt to stabilize the cornea, it is of benefit to place an Elizabethan collar on the patient to prevent further corneal damage. This article discusses the diagnosis, prognosis, and management of corneal emergencies in dogs and cats. Copyright © 2015 Elsevier Inc. All rights reserved.
Robinson, Paulette M; Chuang, Tsai-Der; Sriram, Sriniwas; Pi, Liya; Luo, Xiao Ping; Petersen, Bryon E; Schultz, Gregory S
The role of microRNA (miRNA) regulation in corneal wound healing and scar formation has yet to be elucidated. This study analyzed the miRNA expression pattern involved in corneal wound healing and focused on the effect of miR-133b on expression of several profibrotic genes. Laser-ablated mouse corneas were collected at 0 and 30 minutes and 2 days. Ribonucleic acid was collected from corneas and analyzed using cell differentiation and development miRNA PCR arrays. Luciferase assay was used to determine whether miR-133b targeted the 3' untranslated region (UTR) of transforming growth factor β1 (TGFβ1) and connective tissue growth factor (CTGF) in rabbit corneal fibroblasts (RbCF). Quantitative real-time PCR (qRT-PCR) and Western blots were used to determine the effect of miR-133b on CTGF, smooth muscle actin (SMA), and collagen (COL1A1) in RbCF. Migration assay was used to determine the effect of miR-133b on RbCF migration. At day 2, 37 of 86 miRNAs had substantial expression fold changes. miR-133b had the greatest fold decrease at -14.33. Pre-miR-133b targeted the 3' UTR of CTGF and caused a significant decrease of 38% (P < 0.01). Transforming growth factor β1-treated RbCF had a significant decrease of miR-133b of 49% (P < 0.01), whereas CTGF, SMA, and COL1A1 had significant increases of 20%, 54%, and 37% (P < 0.01), respectively. The RbCF treated with TGFβ1 and pre-miR133b showed significant decreases in expression of CTGF, SMA, and COL1A1 of 30%, 37%, and 28% (P < 0.01), respectively. Finally, there was significant decrease in migration of miR-133b-treated RbCF. Significant changes occur in key miRNAs during early corneal wound healing, suggesting novel miRNA targets to reduce scar formation.
culture of HCECs was possible using adult human serum. We reconstructed the cornea using cultured HCECs and human corneal stroma. The corneal stroma, on which the cell suspension of HCECs was poured, was mildly centrifuged to enhance the HCECs attachment to the stroma. The cell density of HCECs on the reconstructed cornea reached 2,500 cells/mm2. The pump function of the reconstructed cornea was measured with an Ussing chamber. The potential difference in the reconstructed cornea and normal cornea was 0.30 mV and 0.40 mV, respectively; indicating that the pump function of the reconstructed cornea is 75% of that of the normal cornea. The reconstructed cornea was transplanted to a rabbit eye and stayed transparent for 6 months after the operation. Fluorescein labeled cultured HCECs remained on the graft 1 month after the transplantation, indicating that transplanted HCECs contributed to the transparency of the graft. The possibility of using artificial stroma or porcine corneal stroma as a carrier of cultured HCECs was investigated. The artificial stroma made of alkaline-treated collagen could not be sutured but showed good transparency, biocompatibility, and cell-attachability. Porcine corneal stroma, expressing little xeno-sugar antigen alpha-gal epitope, induced no super acute rejection but mild cellular rejection when transplanted in the cornea of animals possessing natural antibody to alpha-gal epitope. The cornea reconstructed with porcine corneal stroma and HCECs had an average cell density of 1721/mm2 and had approximately 60% of the pump function of a normal cornea. As new technologies in corneal transplantation, the application of self immature cells and the direct delivery of cultured HCECs into the anterior chamber were investigated. Part of rat mononuclear cells that were obtained from the bone marrow and injected into the rat anterior chamber transformed into corneal endothelium-like cells, suggesting that self immature cells can transform into corneal
Verstraelen, Sandra; Jacobs, An; De Wever, Bart; Vanparys, Philippe
Measurement of ocular irritancy is a necessary step in the safety evaluation of both industrial and consumer products. Assessment of the acute eye irritation potential is therefore part of the international regulatory requirements for testing of chemicals. The Bovine Corneal Opacity and Permeability (BCOP) assay is generally accepted as a valid in vitro alternative method to the Draize eye irritation test to detect corrosive and severe eye irritants (category 1), but has not proven sensitive enough to discriminate accurately moderate (category 2A/2B) to mild and non-irritating compounds. In the currently accepted BCOP assay, opacity is determined by the amount of light transmission through the cornea, and permeability is determined by the amount of sodium fluorescein dye that passes through all corneal cell layers. Both measurements are used to assign an In Vitro Irritancy Score (IVIS) for prediction of the in vivo ocular irritation potential of a test substance. Nowadays, opacity is measured by an OP-KIT opacitometer providing a center-weighted reading of light transmission by measuring changes in voltage when the transmission of white light passes through the cornea alters. As a consequence, this may underestimate opacity that develops as spots or heterogeneous opaque areas on the periphery of an isolated cornea. A prototype of a laser light-based opacitometer (PLLBO) allowing better measurement of opacities was developed by Van Goethem et al. (2010). This new device showed improved sensitivity to detect subtle changes in corneal transparency. Furthermore, the new opacitometer allowed the analysis of the complete corneal surface and was able to detect more efficiently opaque spots located along the sides of the excised corneas. A further improved prototype of the PLLBO was constructed in combination with a camera and a speckle noise reducer. Treatment conditions of the corneas in the cornea holders were optimized in order to mimic more the real in vivo situation
Fernández, E N; Legarra, A; Martínez, R; Sánchez, J P; Baselga, M
Inbreeding generates covariances between additive and dominance effects (breeding values and dominance deviations). In this work, we developed and applied models for estimation of dominance and additive genetic variances and their covariance, a model that we call "full dominance," from pedigree and phenotypic data. Estimates with this model such as presented here are very scarce both in livestock and in wild genetics. First, we estimated pedigree-based condensed probabilities of identity using recursion. Second, we developed an equivalent linear model in which variance components can be estimated using closed-form algorithms such as REML or Gibbs sampling and existing software. Third, we present a new method to refer the estimated variance components to meaningful parameters in a particular population, i.e., final partially inbred generations as opposed to outbred base populations. We applied these developments to three closed rabbit lines (A, V and H) selected for number of weaned at the Polytechnic University of Valencia. Pedigree and phenotypes are complete and span 43, 39 and 14 generations, respectively. Estimates of broad-sense heritability are 0.07, 0.07 and 0.05 at the base versus 0.07, 0.07 and 0.09 in the final generations. Narrow-sense heritability estimates are 0.06, 0.06 and 0.02 at the base versus 0.04, 0.04 and 0.01 at the final generations. There is also a reduction in the genotypic variance due to the negative additive-dominance correlation. Thus, the contribution of dominance variation is fairly large and increases with inbreeding and (over)compensates for the loss in additive variation. In addition, estimates of the additive-dominance correlation are -0.37, -0.31 and 0.00, in agreement with the few published estimates and theoretical considerations. © 2017 Blackwell Verlag GmbH.
Koulikovska, Marina; Rafat, Mehrdad; Petrovski, Goran; Veréb, Zoltán; Akhtar, Saeed; Fagerholm, Per; Lagali, Neil
Severe shortage of donor corneas for transplantation, particularly in developing countries, has prompted the advancement of bioengineered tissue alternatives. Bioengineered corneas that can withstand transplantation while maintaining transparency and compatibility with host cells, and that are additionally amenable to standardized low-cost mass production are sought. In this study, a bioengineered porcine construct (BPC) was developed to function as a biodegradable scaffold to promote corneal stromal regeneration by host cells. Using high-purity medical-grade type I collagen, high 18% collagen content and optimized EDC-NHS cross-linker ratio, BPCs were fabricated into hydrogel corneal implants with over 90% transparency and four-fold increase in strength and stiffness compared with previous versions. Remarkably, optical transparency was achieved despite the absence of collagen fibril organization at the nanoscale. In vitro testing indicated that BPC supported confluent human epithelial and stromal-derived mesenchymal stem cell populations. With a novel femtosecond laser-assisted corneal surgical model in rabbits, cell-free BPCs were implanted in vivo in the corneal stroma of 10 rabbits over an 8-week period. In vivo, transparency of implanted corneas was maintained throughout the postoperative period, while healing occurred rapidly without inflammation and without the use of postoperative steroids. BPC implants had a 100% retention rate at 8 weeks, when host stromal cells began to migrate into implants. Direct histochemical evidence of stromal tissue regeneration was observed by means of migrated host cells producing new collagen from within the implants. This study indicates that a cost-effective BPC extracellular matrix equivalent can incorporate cells passively to initiate regenerative healing of the corneal stroma, and is compatible with human stem or organ-specific cells for future therapeutic applications as a stromal replacement for treating blinding
... as sand or dust Ultraviolet injuries: Caused by sunlight, sun lamps, snow or water reflections, or arc- ... a corneal injury if you: Are exposed to sunlight or artificial ultraviolet light for long periods of ...
... Causes a Corneal Abrasion? Your eye has other defenses besides the orbital bone: The eyelids and eyelashes ... The Nemours Foundation, iStock, Getty Images, Corbis, Veer, Science Photo Library, Science Source Images, Shutterstock, and Clipart. ...
... lenses to achieve the best vision. Laser vision correction may be an option if you have nearsightedness, ... Editorial team. Related MedlinePlus Health Topics Corneal Disorders Refractive Errors Browse the Encyclopedia A.D.A.M., Inc. ...
... fingernails short, too.Use care when putting in contact lenses. Make sure you clean them properly each day.Don’t sleep in your contact lenses.Trim low-hanging tree branches. Corneal abrasion treatment ...
Schwab, I R
PURPOSE: To evaluate the potential efficacy for autologous and allogeneic expanded corneal epithelial cell transplants derived from harvested limbal corneal epithelial stem cells cultured in vitro for the management of ocular surface disease. METHODS: Human Subjects. Of the 19 human subjects included, 18 (20 procedures) underwent in vitro cultured corneal epithelial cell transplants using various carriers for the epithelial cells to determine the most efficacious approach. Sixteen patients (18 procedures on 17 eyes) received autologous transplants, and 2 patients (1 procedure each) received allogeneic sibling grafts. The presumed corneal epithelial stem cells from 1 patient did not grow in vitro. The carriers for the expanded corneal epithelial cells included corneal stroma, type 1 collagen (Vitrogen), soft contact lenses, collagen shields, and amniotic membrane for the autologous grafts and only amniotic membrane for the allogeneic sibling grafts. Histologic confirmation was reviewed on selected donor grafts. Amniotic membrane as carrier. Further studies were made to determine whether amniotic membrane might be the best carrier for the expanding corneal epithelial cells. Seventeen different combinations of tryspinization, sonication, scraping, and washing were studied to find the simplest, most effective method for removing the amniotic epithelium while still preserving the histologic appearance of the basement membrane of the amnion. Presumed corneal epithelial stem cells were harvested and expanded in vitro and applied to the amniotic membrane to create a composite graft. Thus, the composite graft consisted of the amniotic membrane from which the original epithelium had been removed without significant histologic damage to the basement membrane, and the expanded corneal epithelial stem cells, which had been applied to and had successfully adhered to the denuded amniotic membrane. Animal model. Twelve rabbits had the ocular surface of 1 eye damaged in a standard
Uematsu, Masafumi; Mohamed, Yasser Helmy; Onizuka, Naoko; Ueki, Ryotaro; Inoue, Daisuke; Fujikawa, Azusa; Sasaki, Hitoshi; Kitaoka, Takashi
To evaluate acute corneal permeability changes after instillation of benzalkonium chloride (BAC) using a newly developed in vivo less invasive corneal transepithelial electrical resistance (TER) measurement method in animals and humans. We previously developed an in vivo method for measuring corneal TER using intraocular electrodes in animals. This method can be used to precisely measure the decline of the corneal barrier function after instillation of BAC. To lessen the invasiveness of that procedure, we further refined the method for measuring the corneal TER by developing electrodes that could be placed on the surface of the cornea and in the conjunctival sac instead of inserting them into the anterior chamber. Corneal TER changes before and after exposure to 0.02% BAC were determined in this study using the new device in both rabbits and humans. There was a significant decrease in the corneal TER after exposure of the cornea to 0.02% BAC solution in both rabbits and humans (P<.01). The results of this new less invasive method agreed with those of formerly established anterior chamber methods in rabbit experiments. This new less invasive corneal TER measurement method enables us for the first time to measure TER of the human cornea, allowing safe and reliable investigation of the direct effect of different eye drop treatments on the corneal epithelium. Copyright © 2016 Elsevier Inc. All rights reserved.
Hashimoto, Yoshihide; Funamoto, Seiichi; Sasaki, Shuji; Negishi, Jun; Honda, Takako; Hattori, Shinya; Nam, Kwangwoo; Kimura, Tsuyoshi; Mochizuki, Manabu; Kobayashi, Hisatoshi; Kishida, Akio
The purpose of this study is to demonstrate the feasibility of DALK using a decellularized corneal matrix obtained by HHP methodology. Porcine corneas were hydrostatically pressurized at 980 MPa at 10°C for 10 minutes to destroy the cells, followed by washing with EGM-2 medium to remove the cell debris. The HHP-treated corneas were stained with H-E to assess the efficacy of decellularization. The decellularized corneal matrix of 300 μm thickness and 6.0 mm diameter was transplanted onto a 6.0 mm diameter keratectomy wound. The time course of regeneration on the decellularized corneal matrix was evaluated by haze grading score, fluorescein staining, and immunohistochemistry. H-E staining revealed that no cell nuclei were observed in the decellularized corneal matrix. The decellularized corneal matrices were opaque immediately after transplantation, but became completely transparent after 4 months. Fluorescein staining revealed that initial migration of epithelial cells over the grafts was slow, taking 3 months to completely cover the implant. Histological sections revealed that the implanted decellularized corneal matrix was completely integrated with the receptive rabbit cornea, and keratocytes infiltrated into the decellularized corneal matrix 6 months after transplantation. No inflammatory cells such as macrophages, or neovascularization, were observed during the implantation period. The decellularized corneal matrix improved corneal transparency, and remodelled the graft after being transplanted, demonstrating that the matrix obtained by HHP was a useful graft for corneal tissue regeneration. PMID:26161854
Zhang, Chao; Nie, Xin; Hu, Dan; Liu, Yuan; Deng, Zhihong; Dong, Rui; Zhang, Yongjie; Jin, Yan
Tissue-engineered replacement of diseased or damaged tissue has become a reality for some types of tissue, such as skin and cartilage. Tissue-engineered corneal stroma represents a promising concept to overcome the limitations of cornea replacement with allograft. In this study, porcine cornea was decellularized by a series of extraction methods, and the in vivo biocompatibility of the scaffold was measured subcutaneously in rabbits (n = 8). These were not acutely rejected and no abscesses were observed by hematoxylin and eosin staining at the 8th week, indicating that the scaffolds had good biocompatibility. To investigate the potential value of clinical applications, rabbit stromal keratocytes were implanted onto decellularized scaffolds to fabricate tissue-engineered corneal stroma. Allograft, tissue-engineered corneal stroma, or scaffolds were implanted into a model of corneal ulcer. The survival and reconstruction of corneal transplantation were morphologically evaluated by light and electron microscopy until the 32nd week after implantation. Experiments involving transplantation indicated that the epithelial and stromal defect healed quickly, with improvement in corneal clarity. The integration of the graft was accompanied by neurite ingrowth from the host tissue. By 16 weeks after transplantation, the cornea had gradually regained an intact state similar to that of normal cornea. Our results demonstrate that the tissue-engineered corneal stroma with allogenetic cells is a promising therapeutic method for corneal injury.
phosphoryla- tion, but did not increase proliferation. We have identified in rabbit corneal epithelial cells (RCEC) similar interaction in response to...Inhibitory effect of PGE2 on EGF-induced MAP kinase activity and rabbit corneal epithelial proliferation. Invest Ophthalmol Vis Sci. 2000;41:2164–2169. 4...Dependence of EGF-Induced Increases in Corneal Epithelial Proliferation and Migration on GSK-3 Inactivation Zheng Wang,1 Hua Yang,1 Fan Zhang,1 Zan
Kurtz, Ron M.; Spooner, Greg J. R.; Sletten, Karin R.; Yen, Kimberly G.; Sayegh, Samir I.; Loesel, Frieder H.; Horvath, Christopher; Liu, HsiaoHua; Elner, Victor; Cabrera, Delia; Muenier, Marie-Helene; Sacks, Zachary S.; Juhasz, Tibor
We evaluated the efficacy, safety, and stability of femtosecond laser intrastromal refractive procedures in ex vivo and in vivo models. When compared with longer pulsewidth nanosecond or picosecond laser pulses, femtosecond laser-tissue interactions are characterized by significantly smaller and more deterministic photodisruptive energy thresholds, as well as reduced shock waves and smaller cavitation bubbles. We utilized a highly reliable, all-solid-state femtosecond laser system for all studies to demonstrate clinical practicality. Contiguous tissue effects were achieved by scanning a 5 μm focused laser spot below the corneal surface at pulse energies of approximately 2 - 4 microjoules. A variety of scanning patterns was used to perform three prototype procedures in animal eyes; corneal flap cutting, keratomileusis, and intrastromal vision correction. Superior dissection and surface quality results were obtained for lamellar procedures (corneal flap cutting and keratomileusis). Preliminary in vivo evaluation of intrastromal vision correction in a rabbit model revealed consistent and stable pachymetry changes, without significant inflammation or loss of corneal transparency. We conclude that femtosecond laser technology may be able to perform a variety of corneal refractive procedures with high precision, offering advantages over current mechanical and laser devices and techniques.
Johnson, Thomas E.; Mitchell, Michael A.; Rico, Pedro J.; Fletcher, David J.; Eurell, Thomas E.; Roach, William P.
Mechanisms of tissue damage are investigated for skin and cornea exposures from 1540 nm ('eye safe') laser single pulses of 0.8 milli-seconds. New skin model data point out the advantages of using the Yucatan mini-pig versus the Yorkshire pig for in-vivo skin laser exposures. Major advantages found include similarities in thickness and melanin content when compared with human skin. Histology from Yucatan mini-pig skin exposures and the calculation of an initial ED50 threshold indicate that the main photon tissue interaction may not be solely due to water absorption. In-vitro corneal equivalents compared well with in-vivo rabbit cornea exposure under similar laser conditions. In-vivo and in-vitro histology show that initial energy deposition leading to damage occurs intrastromally, while epithelial cells show no direct injury due to laser light absorption.
To review our previous studies regarding herpes simplex virus type 1 (HSV-1) corneal latency in the rabbit lamellar keratoplasty (LK) and penetrating keratoplasty (PKP) models. Rabbits latently infected with HSV- I received allografts from naive rabbits, and naive rabbits received grafts from rabbits latently infected with HSV-1. In rabbits undergoing LK, viral shedding in tear film and the occurrence of herpetic lesions were investigated for 7 days after operation. In rabbits undergoing PKP, latency-associated transcript (LAT)-positive and -negative HSV- I mutants were used to establish latency. Ninety days after PKP, reactivation of HSV-1 was induced by transcorneal iontophoresis of epinephrine. Viral shedding was then assessed by tear-film swabbing. Donor corneal buttons, recipient corneal rims, and corresponding trigeminal ganglia were analyzed for HSV DNA concentration and viral transcription. In rabbits undergoing LK, the occurrence of positive tear-film cultures and number of days on which corneal epithelial lesions were observed were significantly higher in the operated eyes of latently infected rabbits as compared with controls. In rabbits undergoing PKP, HSV- I could transmit between host and donor tissues both in anterograde and retrograde fashion. LAT-positive virus had a significantly greater ability to transmit. Higher concentrations of HSV DNA detected in cornea and trigeminal ganglia correlated with active viral transcription and higher percentage of viral shedding. Corneas from latently infected rabbits contain HSV-1 DNA that can replicate and transmit after induced reactivation. Our studies provide further evidence for corneal latency of this virus.
Twa, Michael D.; Vantipalli, Srilatha; Singh, Manmohan; Li, Jiasong; Larin, Kirill V.
Corneal biomechanical properties are influenced by several factors, including intraocular pressure, corneal thickness, and viscoelastic responses. Corneal thickness is directly proportional to tissue hydration and can influence corneal stiffness, but there is no consensus on the magnitude or direction of this effect. We evaluated the influence of corneal hydration on dynamic surface deformation responses using optical coherence elastography (OCE). Fresh rabbit eyes (n=10) were prepared by removing the corneal epithelium and dropping with 0.9% saline every 5 minutes for 1 hour, followed by 20% dextran solution every 5 minutes for one hour. Corneal thickness was determined from structural OCT imaging and OCE measurements were performed at baseline and every 20 minutes thereafter. Micron-scale deformations were induced at the apex of the corneal tissue using a spatially-focused (150μm) short-duration (<1ms) air-pulse delivery system. These dynamic tissue responses were measured non-invasively with a phase-stabilized swept source OCT system. The tissue surface deformation response (Relaxation Rate: RR) was quantified as the time constant, over which stimulated tissue recovered from the maximum deformation amplitude. Elastic wave group velocity (GV) was also quantified and correlated with change in corneal thickness due to hydration process. Corneal thickness rapidly increased and remained constant following epithelium removal and changed little thereafter. Likewise, corneal stiffness changed little over the first hour and then decreased sharply after Dextran application (thickness: -46% [-315/682 μm] RR: - 24% [-0.7/2.88 ms-1]; GV: -19% [-0.6/3.2 m/s]). Corneal thickness and corneal stiffness (RR) were well correlated (R2 = .66). Corneal biomechanical properties are highly correlated with tissue hydration over a wide range of corneal thickness and these changes in corneal stiffness are quantifiable using OCE.
Tagawa, Y.; Silverstein, A.M.; Prendergast, R.A.
The local intraocular graft-vs.-host (GVH) reaction, involving the destruction of the corneal endothelial cells of the rabbit host by sensitized donor lymphoid cells, has been used to study the mechanism of corneal allograft rejection. Pretreatment of donor cells with a specific mouse monoclonal hybridoma anti-T cell antibody and complement suppresses the destructive reaction, suggesting that a cellular-immune mechanism is primarily involved. Pretreatment of donor cells with mitomycin-C completely abolishes the local GVH reaction, indicating that the effector lymphocytes must undergo mitosis within the eye before they can engage in target cell destruction. Finally, studies of the local GVH reaction in irradiated leukopenic recipients or in preinflamed rabbit eyes suggest that host leukocytes may contribute nonspecifically to enhance the destructive process. These studies show that the local ocular GVH reaction may provide a useful model for the study of the mechanisms involved in the rejection of corneal allografts.
Tandon, Ashish; Tovey, Jonathan C K; Waggoner, Michael R; Sharma, Ajay; Cowden, John W; Gibson, Daniel J; Liu, Yuanjing; Schultz, Gregory S; Mohan, Rajiv R
This study investigated the efficacy and safety of vorinostat, a deacetylase (HDAC) inhibitor, in the treatment of laser-induced corneal haze following photorefractive keratectomy (PRK) in rabbits in vivo and transforming growth factor beta 1 (TGFβ1) -induced corneal fibrosis in vitro. Corneal haze in rabbits was produced with -9.00 diopters (D) PRK. Fibrosis in cultured human and rabbit corneal fibroblasts was activated with TGFβ1. Vorinostat (25 μm) was topically applied once for 5 minutes on rabbit cornea immediately after PRK for in vivo studies. Vorinostat (0 to 25 μm) was given to human/rabbit corneal fibroblasts for 5 minutes or 48 hours for in vitro studies. Slit-lamp microscopy, TUNEL assay, and trypan blue were used to determined vorinostat toxicity, whereas real-time polymerase chain reaction, immunocytochemistry, and immunoblotting were used to measure its efficacy. Single 5-minute vorinostat (25 μm) topical application on the cornea following PRK significantly reduced corneal haze (P<.008) and fibrotic marker proteins (α-smooth muscle actin and f-actin; P<.001) without showing redness, swelling, or inflammation in rabbit eyes in vivo screened 4 weeks after PRK. Vorinostat reduced TGFβ1-induced fibrosis in human and rabbit corneas in vitro in a dose-dependent manner without altering cellular viability, phenotype, or proliferation. Vorinostat is non-cytotoxic and safe for the eye and has potential to prevent laser-induced corneal haze in patients undergoing PRK for high myopia. Copyright 2012, SLACK Incorporated.
To report a rare case of corneal honeybee sting. The corneal honeybee stinger was removed under slit-lamp guidance using a 27-gauge needle. Corneal edema resolved by 90% the next day after removal of the honeybee stinger without using topical steroids. The patient's condition improved significantly after removal of the corneal honeybee stinger, and corneal edema disappeared. The patient was evaluated in 1 week and then 3 months with permanent mild central corneal opacity.
Degenerative or hereditary corneal diseases are sometimes difficult to discriminate. Corneal dystrophies affect approximately 0.09 % of the population. They are identified by the IC3D classification based on their phenotype, genotype and evidence gathered for their diagnosis. Practically, the ophthalmologist manages functional symptoms, such as recurrent erosions, visual loss and amblyopia, photophobia, foreign body sensation, and sometimes pain and aesthetic concerns. Medical treatments consist of drops to promote healing, ointments, hyperosmotic agents and bandage contact lenses. Less invasive surgical treatments are used as second line therapy (phototherapeutic keratectomy, lamellar keratectomy). More invasive procedures may eventually be utilized (lamellar or penetrating keratoplasty). Anterior lamellar or endothelial keratoplasty are now preferred to penetrating keratoplasty, although the latter still remains the only possible option in some cases. Some rare dystrophies require coordinated and comprehensive medical care. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
Degenerative or hereditary corneal diseases are sometimes difficult to discriminate. Corneal dystrophies affect approximately 0.09% of the population. They are identified by the IC3D classification based on their phenotype, genotype and evidence gathered for their diagnosis. In practice, the ophthalmologist manages functional symptoms such as recurrent erosions, visual loss and amblyopia, photophobia, foreign body sensation, and sometimes pain and aesthetic concerns. Medical treatments consist of drops to promote healing, ointments, hyperosmotic agents and bandage contact lenses. Less invasive surgical treatments are used as second line therapy (phototherapeutic keratectomy, lamellar keratectomy). More invasive procedures may eventually be utilized (lamellar or penetrating keratoplasty). Anterior lamellar or endothelial keratoplasty are now preferred to penetrating keratoplasty, although the latter still remains the only possible option in some cases. Some rare dystrophies require coordinated and comprehensive medical care. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
Choi, Sang Ouk; Jeon, Hyun Sun; Hyon, Joon Young; Oh, Yun-Jung; Wee, Won Ryang; Chung, Tae-young; Shin, Young Joo; Kim, Jeong Won
Background Wound healing of the endothelium occurs through cell enlargement and migration. However, the peripheral corneal endothelium may act as a cell resource for the recovery of corneal endothelium in endothelial injury. Aim To investigate the recovery process of corneal endothelial cells (CECs) from corneal endothelial injury. Methods Three patients with unilateral chemical eye injuries, and 15 rabbit eyes with corneal endothelial chemical injuries were studied. Slit lamp examination, specular microscopy, and ultrasound pachymetry were performed immediately after chemical injury and 1, 3, 6, and 9 months later. The anterior chambers of eyes from New Zealand white rabbits were injected with 0.1 mL of 0.05 N NaOH for 10 min (NaOH group). Corneal edema was evaluated at day 1, 7, and 14. Vital staining was performed using alizarin red and trypan blue. Results Specular microscopy did not reveal any corneal endothelial cells immediately after injury. Corneal edema subsided from the periphery to the center, CEC density increased, and central corneal thickness decreased over time. In the animal study, corneal edema was greater in the NaOH group compared to the control at both day 1 and day 7. At day 1, no CECs were detected at the center and periphery of the corneas in the NaOH group. Two weeks after injury, small, hexagonal CECs were detected in peripheral cornea, while CECs in mid-periphery were large and non-hexagonal. Conclusions CECs migrated from the periphery to the center of the cornea after endothelial injury. The peripheral corneal endothelium may act as a cell resource for the recovery of corneal endothelium. PMID:26378928
Gore, Daniel M; O'Brart, David P; French, Paul; Dunsby, Chris; Allan, Bruce D
To measure corneal riboflavin penetration using different transepithelial iontophoresis protocols. Freshly enucleated rabbit eyes were divided into nine treatment groups of 4 eyes. One group, in which 0.1% wt/vol riboflavin was applied for 30 minutes without iontophoresis after corneal epithelial debridement, acted as a control. The remaining groups were treated with an intact epithelium using different riboflavin formulations and varying iontophoresis current, soak, and rinse times. After riboflavin application, eyes were snap frozen in liquid nitrogen. Corneal cross sections 35 μm thick were then imaged immediately by two-photon fluorescence microscopy, using image processing software to quantify stromal riboflavin concentration at different corneal depths. In the epithelium-on iontophoresis treatment groups, greater stromal riboflavin penetration was achieved with higher-concentration riboflavin solutions, greater iontophoresis dosage, and longer solution contact times. A protocol utilizing 0.25% wt/vol riboflavin with benzalkonium chloride (BAC) 0.01% and two cycles of applied current and subsequent soaking (1 mA 5 minutes, soak 5 minutes; 0.5 mA 5 minutes, soak 5 minutes) achieved similar stromal riboflavin penetration to epithelium-off controls. The best-performing non-BAC-containing protocol produced stromal riboflavin penetration approximately 60% that of epithelium-off controls. Riboflavin solutions containing saline resulted in minimal stromal penetration. Riboflavin loading within the epithelium was equivalent to or higher than that in the subjacent stroma, despite rinsing the ocular surface with balanced salt solution. Modified iontophoresis protocols can significantly improve transepithelial riboflavin penetration in experimental corneal collagen cross-linking.
Moore, Phillip Anthony
The cornea is naturally transparent. Anything that interferes with the cornea's stromal architecture, contributes to blood vessel migration, increases corneal pigmentation, or predisposes to corneal edema, disrupts the corneas transparency and indicates corneal disease. The color, location, and shape and pattern of a corneal lesion can help in determining the underlying cause for the disease. Corneal disease is typically divided into congenital or acquired disorders. Congenital disorders, such as corneal dermoids are rare in cats, whereas acquired corneal disease associated with nonulcerative or ulcerative keratitis is common. Primary ocular disease, such as tear film instability, adenexal disease (medial canthal entropion, lagophthalmus, eyelid agenesis), and herpes keratitis are associated with the majority of acquired corneal disease in cats. Proliferative/eosinophilic keratitis, acute bullous keratopathy, and Florida keratopathy are common feline nonulcerative disorders. Nonprogressive ulcerative disease in cats, such as chronic corneal epithelial defects and corneal sequestration are more common than progressive corneal ulcerations.
Inoue, Tomoyuki; Hara, Yuko; Kobayashi, Takeshi; Zheng, Xiaodong; Suzuki, Takashi; Shiraishi, Atsushi; Ohashi, Yuichi
To describe a characteristic form of the corona sign and its clinical relevance to the degree of corneal endothelial decompensation and investigate the underlying mechanism using a rabbit model. These observational cases include 31 patients undergoing penetrating keratoplasty (PKP) and 15 patients undergoing Descemet stripping automated endothelial keratoplasty (DSAEK) with special attention to the circumferentially developed corneal epithelial edema. We also conducted a laboratory observation of horizontal water flow in the rabbit cornea. We consistently observed the corona sign at the superior periphery during the initial stage of corneal endothelial decompensation after PKP. With progressive corneal endothelial cellular loss, the epithelial edema gradually expanded circumferentially in the periphery. The endothelial cellular density associated with the corona sign significantly (P < 0.01) decreased compared with that without the sign. The endothelial cellular density decreased significantly (P < 0.05) in cases with a circumferential corona sign compared with a superior corona sign. After DSAEK, however, the corneal epithelial edema subsided from the center but persisted peripherally as a corona sign in all cases. By 3 months postoperatively, the epithelial edema was confined to the superior periphery along with uneventful corneal endothelial healing. Rabbit experiments showed that total corneal endothelial decompensation decreased the horizontal intracorneal water migration (Inoue-Ohashi phenomenon) in the corneal periphery and induced peripheral corneal edema. The slit-lamp microscopic findings of the corona-like epithelial edema in the peripheral cornea are associated with the stage of corneal endothelial function. To support this, the developmental mechanism of the corona sign was demonstrated experimentally.
Evaluating the toxicity/fixation balance for corneal cross-linking with sodium hydroxymethylglycinate (SMG) and riboflavin-UVA (CXL) in an ex vivo rabbit model using confocal laser scanning fluorescence microscopy
Kim, Su-Young; Babar, Natasha; Takaoka, Anna; Zyablitskaya, Mariya; Nagasaki, Takayuki; Trokel, Stephen L.; Paik, David C.
Purpose To develop methods to delineate the relationship between endothelial cell toxicity and tissue fixation (toxicity/fixation) using sodium hydroxymethylglycinate (SMG), a formaldehyde releaser, and riboflavin-UVA (CXL) for therapeutic tissue cross-linking of the cornea. Methods Eleven (11) fresh cadaveric rabbit heads were used for ex vivo corneal cross-linking simulation. Following epithelial debridement, the tissue was exposed to 1/4 Max (9.765mM) or 1/3Max (13.02mM) SMG at pH 8.5 for 30min or riboflavin-UVA (CXL). The contralateral cornea served as a paired control. Post-exposure, cross-linking efficacy was determined by thermal denaturation temperature (Tm) and endothelial damage was assessed using calcein AM and ethidium homodimer staining (Live/Dead Kit). Confocal laser scanning fluorescence microscopy was used to generate live/dead cell counts following a standardized algorithm. Results The ΔTm following CXL, 1/3 SMG, and 1/4 SMG was 2.19±0.91°C, 1.33±0.49 °C, and 1.10 ±0.46 °C, respectively. Endothelial cell damage was expressed as the percent of dead cells/live + dead cells counted per high powered field. The values were 2.95±1.74% (control) and 8.86±11.10% (CXL) [p=0.390]; 0.98±0.20% (control) and 19.53±32.22% (1/3max SMG) [p=0.426]; and 2.70±2.37% (control) and 2.84±2.24% (1/4 max SMG) [p=0.938];. The values for endothelial toxicity were then indexed over the shift in Tm in order to yield a toxicity/fixation index. The values were as follows: 2.70 for CXL, 13.95 for 1/3 max, and 0.13 for 1/4 max. Conclusions Quarter max (1/4 Max = 9.765mM) SMG effectively cross-linked tissue and was non-toxic to endothelial cells. Thus, SMG is potentially a compound that could achieve both desired effects. PMID:26807905
Jang, In-Keun; Ahn, Jae-Il; Shin, Jun-Seop; Kwon, Young-Sam; Ryu, Yang-Hwan; Lee, Jeong-Kyu; Park, Jung-Keug; Song, Kye-Yong; Yang, Eun-Kyung; Kim, Jae-Chan
The purpose of this article was to evaluate the graft efficacy of reconstructed corneal layer, composed of autologous corneal epithelium and fibroblasts on a lyophilized amniotic membrane (LAM), in a severely alkali-burned corneal model. After biopsy specimens were obtained from the left eyes of 24 rabbits, the corneal epithelial cells and fibroblasts were expanded in vitro and the corneal layer was reconstructed on LAM. Thirty-six eyes of rabbits underwent alkali burn (1 N NaOH, 30 s) to create a limbal deficiency and a deeply damaged corneal stroma. Four weeks later, group 1 underwent a graft of the reconstructed corneal layer composed of autologous corneal epithelium and fibroblasts on LAM. Group 2 was transplanted with a graft of the reconstructed autologous corneal epithelium, and group 3 served as a control without surgery. Wound healing and stabilization of the ocular surfaces occurred much faster in group 1 than in groups 2 and 3. The eyes in group 3 revealed typical limbal deficiencies with conjuctivalization and persistent corneal epithelial defects. However, the corneas in group 1 developed only mild peripheral neovascularization. Immunohistochemical staining in group 1 demonstrated that p63, cytokeratin 3, E-cadherin, transforming growth factor (TGF)-beta1, and collagen IV were expressed strongly in the corneal epithelium and basement membrane. On the basis of these results, transplantation of the reconstructed corneal layer, composed of autologous corneal epithelium and fibroblasts on LAM, partially accelerated the recovery of the alkali-injured rabbit ocular surface, and might be useful therapeutically for the treatment of patients with severely damaged cornea.
Gupta, Suneel; Rodier, Jason T.; Sharma, Ajay; Giuliano, Elizabeth A.; Sinha, Prashant R.; Hesemann, Nathan P.; Ghosh, Arkasubhra; Mohan, Rajiv R.
Corneal scarring is due to aberrant activity of the transforming growth factor β (TGFβ) signaling pathway following traumatic, mechanical, infectious, or surgical injury. Altered TGFβ signaling cascade leads to downstream Smad (Suppressor of mothers against decapentaplegic) protein-mediated signaling events that regulate expression of extracellular matrix and myogenic proteins. These events lead to transdifferentiation of keratocytes into myofibroblasts through fibroblasts and often results in permanent corneal scarring. Hence, therapeutic targets that reduce transdifferentiation of fibroblasts into myofibroblasts may provide a clinically relevant approach to treat corneal fibrosis and improve long-term visual outcomes. Smad7 protein regulates the functional effects of TGFβ signaling during corneal wound healing. We tested that targeted delivery of Smad7 using recombinant adeno-associated virus serotype 5 (AAV5-Smad7) delivered to the corneal stroma can inhibit corneal haze post photorefractive keratectomy (PRK) in vivo in a rabbit corneal injury model. We demonstrate that a single topical application of AAV5-Smad7 in rabbit cornea post-PRK led to a significant decrease in corneal haze and corneal fibrosis. Further, histopathology revealed lack of immune cell infiltration following AAV5-Smad7 gene transfer into the corneal stroma. Our data demonstrates that AAV5-Smad7 gene therapy is relatively safe with significant potential for the treatment of corneal disease currently resulting in fibrosis and impaired vision. PMID:28339457
Gupta, Suneel; Rodier, Jason T; Sharma, Ajay; Giuliano, Elizabeth A; Sinha, Prashant R; Hesemann, Nathan P; Ghosh, Arkasubhra; Mohan, Rajiv R
Corneal scarring is due to aberrant activity of the transforming growth factor β (TGFβ) signaling pathway following traumatic, mechanical, infectious, or surgical injury. Altered TGFβ signaling cascade leads to downstream Smad (Suppressor of mothers against decapentaplegic) protein-mediated signaling events that regulate expression of extracellular matrix and myogenic proteins. These events lead to transdifferentiation of keratocytes into myofibroblasts through fibroblasts and often results in permanent corneal scarring. Hence, therapeutic targets that reduce transdifferentiation of fibroblasts into myofibroblasts may provide a clinically relevant approach to treat corneal fibrosis and improve long-term visual outcomes. Smad7 protein regulates the functional effects of TGFβ signaling during corneal wound healing. We tested that targeted delivery of Smad7 using recombinant adeno-associated virus serotype 5 (AAV5-Smad7) delivered to the corneal stroma can inhibit corneal haze post photorefractive keratectomy (PRK) in vivo in a rabbit corneal injury model. We demonstrate that a single topical application of AAV5-Smad7 in rabbit cornea post-PRK led to a significant decrease in corneal haze and corneal fibrosis. Further, histopathology revealed lack of immune cell infiltration following AAV5-Smad7 gene transfer into the corneal stroma. Our data demonstrates that AAV5-Smad7 gene therapy is relatively safe with significant potential for the treatment of corneal disease currently resulting in fibrosis and impaired vision.
Uzunalli, G; Soran, Z; Erkal, T S; Dagdas, Y S; Dinc, E; Hondur, A M; Bilgihan, K; Aydin, B; Guler, M O; Tekinay, A B
Defects in the corneal stroma caused by trauma or diseases such as macular corneal dystrophy and keratoconus can be detrimental for vision. Development of therapeutic methods to enhance corneal regeneration is essential for treatment of these defects. This paper describes a bioactive peptide nanofiber scaffold system for corneal tissue regeneration. These nanofibers are formed by self-assembling peptide amphiphile molecules containing laminin and fibronectin inspired sequences. Human corneal keratocyte cells cultured on laminin-mimetic peptide nanofibers retained their characteristic morphology, and their proliferation was enhanced compared with cells cultured on fibronectin-mimetic nanofibers. When these nanofibers were used for damaged rabbit corneas, laminin-mimetic peptide nanofibers increased keratocyte migration and supported stroma regeneration. These results suggest that laminin-mimetic peptide nanofibers provide a promising injectable, synthetic scaffold system for cornea stroma regeneration. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Chen, Varda; Landshman, Nahum; Belkin, Michael
The effect of repeated low power He-Ne laser on rabbit's corneal epithelium was studied after 3 daily sessions. Under certain irradiation parameters, low power He-Ne laser irradiation was found to change the mitotic rate in the basal layer of intact corneal epithelium. Three daily irradiations for 3 or 10 minutes increased the mitotic index while 30 minutes irradiations decreased it.
Schultz, C L; Morck, D W; McKay, S G; Olson, M E; Buret, A
Using a new animal model, the aims of this study were to assess the role played by purified lipopolysaccharide (LPS) and neutrophils in the pathogenesis of acute red-eye reactions (ARE) and corneal ulcers. In addition, IL-1 alpha was assessed for its implications in the formation of corneal ulcers. Following corneal abrasion, eyes of rabbits underwent single or double exposures to various doses of LPS from Pseudomonas aeruginosa or Serratia marcescens. This protocol induced ARE symptoms, and their severity depended on the dosage, number of LPS exposures, and type of LPS used (LPS from S. marcescens showing highest virulence). Corneal ulcers were induced by delivering a high dose of Serratia LPS (100 micrograms) followed by a low dose (10 micrograms). Histopathological examination revealed that both ARE and corneal ulceration were associated with prominent neutrophil infiltration. In addition, many lymphocytes and other monocytic cells infiltrated ulcerated ocular tissue. Tear fluids obtained from ulcerated eyes contained high concentrations of a protein recognized by anti-rabbit IL-1 alpha antibodies as demonstrated by immunoblotting studies. The results indicate that LPS can induce ARE and corneal ulceration in the absence of any live bacteria. Moreover, the findings implicate the accumulation of neutrophils and IL-1 alpha-related proteins in the pathogenesis of ARE and corneal ulcers.
Twining, S.S.; Wilson, P.M.
The vitamin A-deficient keratinized cornea is very susceptible to ulceration possibly due to altered stromal components. In this study the proteoglycans present in the corneal stroma of vitamin A-deficient, pair-fed and normal rabbits were compared. Rabbits after weaning were placed on a vitamin A deficient diet, the same diet with retinyl palmitate added (pair-fed) or normal rabbit chow. After 5 months, the corneas of the vitamin A-deficient animals became keratinized. The corneal components were then labeled by injection of /sup 3/H-leucine and Na/sup 35/SO/sub 4/ into the anterior chamber of the eyes on 3 successive days. On the 4th day the animals were sacrificed the corneas removed and dissected. The labeled corneal stromas were extracted with 4 M GuHCl and the components separated on a DEAE-Sepharose column. The proteoglycans were eluted with 0.5 M and 1.0 M NaCl. The 1.0 M NaCl fraction (mainly keratin sulfate proteoglycans) was increased 25% in the vitamin A-deficient corneas over that for the pair-fed and normal corneas. These proteoglycans from the deficient corneas gave a different elution pattern on Octyl-Sepharose eluted with a Triton X-100 gradient than those from the pair-fed corneas. The total labeled proteoglycans were similar in the stromas from the 3 types of rabbits. These results indicate the various corneal proteoglycan ratios differ under vitamin A deficiency conditions.
Williams, Lynn B; Pinard, Chantale L
Corneal ulceration is commonly diagnosed by equine veterinarians. A complete ophthalmic examination as well as fluorescein staining, corneal cytology, and corneal bacterial (aerobic) and fungal culture and sensitivity testing are necessary for all infected corneal ulcers. Appropriate topical antibiotics, topical atropine, and systemic NSAIDs are indicated for all corneal ulcers. If keratomalacia (melting) is observed, anticollagenase/antiprotease therapy, such as autologous serum, is indicated. If fungal infection is suspected, antifungal therapy is a necessity. Subpalpebral lavage systems allow convenient, frequent, and potentially long-term therapy. Referral corneal surgeries provide additional therapeutic options when the globe's integrity is threatened or when improvement has not been detected after appropriate therapy.
Koizumi, Noriko; Okumura, Naoki; Kinoshita, Shigeru
This review describes our recent attempts to develop new therapeutic modalities for corneal endothelial disease using animal models including non-human primate model in which the proliferative ability of corneal endothelial cells is severely limited, as is the case in humans. First, we describe our attempt to develop new surgical treatments using cultivated corneal endothelial cells for advanced corneal endothelial dysfunction. It includes two different approaches; a "corneal endothelial cell sheet transplantation" with cells grown on a type-I collagen carrier, and a "cell-injection therapy" combined with the application of Rho-kinase (ROCK) inhibitor. Recently, it was reported that the selective ROCK inhibitor, Y-27632, promotes cell adhesion and proliferation and inhibits the apoptosis of primate corneal endothelial cells in culture. When cultivated corneal endothelial cells were injected into the anterior chamber of animal eyes in the presence of ROCK inhibitor, endothelial cell adhesion was promoted and the cells achieved a high cell density and a morphology similar to corneal endothelial cells in vivo. We are also trying to develop a novel medical treatment for the early phase of corneal endothelial disease by the use of ROCK inhibitor eye drops. In rabbit and monkey experiments using partial endothelial dysfunction models, corneal endothelial wound healing was accelerated by the topical application of ROCK inhibitor to the ocular surface, and resulted in the regeneration of a corneal endothelial monolayer with a high endothelial cell density. We are now trying to advance the clinical application of these new therapies for patients with corneal endothelial dysfunction. Copyright © 2011 Elsevier Ltd. All rights reserved.
Lazcano-Gomez, Gabriel; Ancona-Lezama, David; Gil-Carrasco, Felix; Jimenez-Roman, Jesus
Purpose To determine whether topical application of travoprost 0.004% induces changes in corneal biomechanical properties affecting intraocular pressure (IOP) values in rabbits. Methods Both eyes of 10 New Zealand rabbits were measured 3 times with the Ocular Response Analyzer (ORA) before treatment. Each measurement included corneal hysteresis (CH), corneal resistance factor (CRF), corneal-corrected IOP (IOPcc), and Goldmann equivalent IOP (IOPg). A drop of travoprost 0.004% was applied once daily in right eyes for 3 months; left eyes received no treatments. After 3 months of treatment both eyes of all rabbits were again measured 3 times. After complete keratectomy of both eyes, tissues prepared with hematoxylin-eosin stain were analyzed by means of light microscopy. Results The mean pre- and post-treatment IOPg, respectively, for right eyes was 9.92 ± 5.64 mm Hg and 7.62 ± 2.99 mm Hg (P = 0.027); IOPcc, 19.81 ± 5.25 mm Hg and 17.79 ± 4.09 mm Hg (P = 0.063); CRF, 1.65 ± 1.63 mm Hg and 2.18 ± 2.50 mm Hg (P = 0.266); and CH, 2.79 ± 1.74 mm Hg and 2.64 ± 2.08 mm Hg (P = 0.72). Mean post-treatment right and left eye IOPg values were, respectively, 7.62 ± 2.99 and 10.30 ± 4.40 (P = 0.002); IOPcc, 17.79 ± 4.09 mm Hg and 20.37 ± 4.32 mm Hg (P = 0.009); CRF, 1.65 ± 1.63 mm Hg and 2.17 ± 2.47 mm Hg (P = 0.274); and CH, 2.79 ± 1.74 mm Hg and 2.54 ± 2.08 mm Hg (P = 0.575). No difference in CH and CRF was observed between treated and untreated eyes. Conclusions Post-treatment reduction of IOP in treated eyes was a direct hypotensive effect of travoprost 0.004% and was not affected by changes in corneal biomechanical properties (CH and CRF), resulting in real lower IOP values. PMID:27330476
Abd Ghafar, Norzana; Ker-Woon, Choy; Hui, Chua Kien; Mohd Yusof, Yasmin Anum; Wan Ngah, Wan Zurinah
The study aimed to evaluate the effects of Acacia honey (AH) on the migration, differentiation and healing properties of the cultured rabbit corneal fibroblasts. Stromal derived corneal fibroblasts from New Zealand White rabbit (n = 6) were isolated and cultured until passage 1. In vitro corneal ulcer was created using a 4 mm corneal trephine onto confluent cultures and treated with basal medium (FD), medium containing serum (FDS), with and without 0.025 % AH. Wound areas were recorded at day 0, 3 and 6 post wound creation. Genes and proteins associated with wound healing and differentiation such as aldehyde dehydrogenase (ALDH), vimentin, alpha-smooth muscle actin (α-SMA), collagen type I, lumican and matrix metalloproteinase 12 (MMP12) were evaluated using qRT-PCR and immunocytochemistry respectively. Cells cultured with AH-enriched FDS media achieved complete wound closure at day 6 post wound creation. The cells cultured in AH-enriched FDS media increased the expression of vimentin, collagen type I and lumican genes and decreased the ALDH, α-SMA and MMP12 gene expressions. Protein expression of ALDH, vimentin and α-SMA were in accordance with the gene expression analyses. These results demonstrated AH accelerate corneal fibroblasts migration and differentiation of the in vitro corneal ulcer model while increasing the genes and proteins associated with stromal wound healing.
Yin, Zhaohong; Pintea, Victorina; Lin, Yanping; Hammock, Bruce D.
Purpose. The purpose of this study was to determine whether 25-hydroxyvitamin D3 (25(OH)D3) and/or its active metabolite, 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3), can enhance corneal epithelial barrier function. The authors also determined if corneas contain mRNA for the vitamin D receptor (VDR) and 1α-hydroxylase, the enzyme required to convert 25(OH)D3 to 1,25(OH)2D3, and measured vitamin D metabolite concentrations in aqueous and vitreous humor. Methods. RT-PCR was used to examine mouse, rabbit, and human corneal epithelial VDR and 1α-hydroxylase mRNA. Vitamin D metabolites were measured using a selective vitamin D derivatizing agent and mass spectroscopy. Barrier function experiments were performed by measuring inulin permeability (IP) and/or transepithelial resistance (TER) in control, 25(OH)D3-, and 1,25(OH)2D3-treated human and rabbit corneal epithelial monolayers cultured on permeable inserts. Ca2+ was removed, then reintroduced to the culture medium while IP and TER readings were taken. Occludin levels were examined using Western blotting. Results. All corneal samples were positive for both VDR and 1α-hydroxylase mRNA. All vitamin D metabolites except for unhydroxylated vitamin D3 were detected in aqueous and vitreous humor. Epithelial cells showed increased TER, decreased IP, and increased occludin levels when cultured with 25(OH)D3 and 1,25(OH)2D3. Conclusions. We conclude that corneas contain mRNA for VDR and 1α-hydroxylase as well as significant vitamin D concentrations. 25(OH)D3 and its active metabolite 1,25(OH)2D3, both enhance corneal epithelial barrier function. PMID:21715350
Wang, Kai-di; Zhang, Jin-song; Yan, Pan-shi
To study the corneal permeability of three different pirenzepine eye-drop solutions and provide reference for further clinical use. Sixty-three New Zealand white rabbits were divided into three groups. Each group of rabbits received 2% pirenzepine (pirenzepine group), 2% pirenzepine with 0.1% hyaluronic acid (hyaluronic acid group), or 2% pirenzepine with 0.1% azone (azone group). One drop eye-drops was applied to conjunctive sac every 5 min for six times. Aqueous samples were obtained from each group at 0.5, 1.0, 2.0, 4.0, 8.0, 12.0, 24.0 h after the last drop, respectively. Concentration of pirenzepine in these samples was determined by the HPLC (high pressure liquid chromatography). Stimulation symptom of rabbit eyes was also observed. The concentrations of pirenzepine in aqueous humor were (0.40 +/- 0.06) microg/ml at 0.5 h, (0.53 +/- 0.03) microg/ml at 1.0 h, (1.52 +/- 0.33) microg/ml at 2.0 h and (0.15 +/- 0.02) microg/ml at 4.0 h in pirenzepine group. Aqueous humor concentration of pirenzepine in both 2% pirenzepine with 0.1% azone and 2% pirenzepine with 0.1% hyaluronic acid were significantly higher than that of single pirenzepine application, and their bioavailability in the groups with combinations of pirenzepine with 0.1% azone or 0.1% hyaluronic acid were 23.0 times and 3.4 times higher than that of single pirenzepine usage. No obvious irritate symptom was found in rabbit of all three groups after eye-drop applying. The combination application of pirenzepine with azone or hyaluronic acid has higher corneal permeability compared with pirenzepine alone. This result indicates that azone and hyaluronic acid could be used in pirenzepine eye-drop solution to increase corneal permeability.
Gatlin, Joel; Melkus, Michael W; Padgett, Angela; Petroll, W Matthew; Cavanagh, H Dwight; Garcia, J Victor; Jester, James V
Numerous studies have shown that fibroblasts play an important role in corneal wound healing, however, the dynamic cellular events underlying wound tissue organization and contraction remain unclear. The purpose of this study was to develop a system to enable live cell imaging of corneal wound healing fibroblasts in situ. To this end, concentrated preparations of an RD114 pseudotyped MLV-based vector expressing the enhanced green fluorescent protein (EGFP) were evaluated in vitro for gene transfer efficiency using cultured rabbit corneal keratocytes. Primary rabbit keratocytes were efficiently labeled in vitro (up to 50% EGFP(+)) at a low multiplicity of infection (MOI=10). To evaluate this gene transfer vector in vivo, rabbit corneal fibroblasts were transduced by direct application of vector supernatant to injured corneas following lamellar keratectomy. Fluorescent fibroblasts were then visualized in situ using epifluorescence microscopy and multiphoton confocal microscopy of excised fresh tissue at multiple time points from 14 days to four months following gene transfer. Fourteen days post-transduction, labeled fibroblasts expressing EGFP were readily detectable by fluorescence microscopy. Detectable fluorescence was noted up to eight weeks post-transduction. Labeled fibroblasts were detected in clusters located predominantly along the margin circumscribing the wound and to a lesser extent within the wound area. Cell growth in clusters was suggestive of the expansion of individual transduced clones. High-resolution imaging showed fluorescent fibroblasts to have a broad, flattened, dendritic morphology, distinct from the spindle shape of cultured fibroblasts. Utilizing multiphoton confocal microscopy, three-dimensional imaging of viable, labeled cells showed wound healing fibroblasts to be extensively interconnected and multi-layered within the corneal wound. These results demonstrate that rabbit corneal fibroblasts can be efficiently transduced in vitro and in
Hillyer, E V
Pet rabbits are becoming more common, and rabbit owners are demanding quality veterinary care. This article provides a broad overview of pet rabbit medicine, which is a relatively new field compared to laboratory and farm rabbit medicine. The most common differential diagnoses for presenting complaints are summarized in table form. Disease conditions are reviewed individually in the text. Sources of further information on veterinary care of rabbits are listed throughout the text, in an appendix, and in the references.
Tandon, Ashish; Tovey, Jonathan C.K.; Waggoner, Michael R.; Sharma, Ajay; Cowden, John W.; Gibson, Daniel J.; Liu, Yuanjing; Schultz, Gregory S.; Mohan, Rajiv R.
PURPOSE This study investigated the efficacy and safety of vorinostat, a deacetylase (HDAC) inhibitor, in the treatment of laser-induced corneal haze following photorefractive keratectomy (PRK) in rabbits in vivo and transforming growth factor beta 1 (TGFβ1) -induced corneal fibrosis in vitro. METHODS Corneal haze in rabbits was produced with −9.00 diopters (D) PRK. Fibrosis in cultured human and rabbit corneal fibroblasts was activated with TGFβ1. Vorinostat (25 μm) was topically applied once for 5 minutes on rabbit cornea immediately after PRK for in vivo studies. Vorinostat (0 to 25 μm) was given to human/rabbit corneal fibroblasts for 5 minutes or 48 hours for in vitro studies. Slit-lamp microscopy, TUNEL assay, and trypan blue were used to determined vorinostat toxicity, whereas real-time polymerase chain reaction, immunocytochemistry, and immunoblotting were used to measure its efficacy. RESULTS Single 5-minute vorinostat (25 μm) topical application on the cornea following PRK significantly reduced corneal haze (P<.008) and fibrotic marker proteins (α-smooth muscle actin and f-actin; P<.001) without showing redness, swelling, or inflammation in rabbit eyes in vivo screened 4 weeks after PRK. Vorinostat reduced TGFβ1-induced fibrosis in human and rabbit corneas in vitro in a dose-dependent manner without altering cellular viability, phenotype, or proliferation. CONCLUSIONS Vorinostat is non-cytotoxic and safe for the eye and has potential to prevent laser-induced corneal haze in patients undergoing PRK for high myopia. PMID:22386369
Although comparison phakometry has been used by a number of studies to measure posterior corneal shape, these studies have not calculated the size of the posterior corneal zones of reflection they assessed. This paper develops paraxial equations for calculating posterior corneal zones of reflection, based on standard keratometry equations and equivalent mirror theory. For targets used in previous studies, posterior corneal reflection zone sizes were calculated using paraxial equations and using exact ray tracing, assuming spherical and aspheric corneal surfaces. Paraxial methods and exact ray tracing methods give similar estimates for reflection zone sizes less than 2 mm, but for larger zone sizes ray tracing methods should be used.
Zhou, Chuanqing; Yu, Lei; Ren, Qiushi
Purpose: To study correlation among corneal asphericity, higher-order aberrations and visual performance for eyes of virgin myopia and postoperative laser in situ keratomileusis (LASIK). Methods: There were 320 candidates 590 eyes for LASIK treatment included in this study. The mean preoperative spherical equivalence was -4.35+/-1.51D (-1.25 to -9.75), with astigmatism less than 2.5 D. Corneal topography maps and contrast sensitivity were measured and analyzed for every eye before and one year after LASIK for the analysis of corneal asphericity and wavefront aberrations. Results: Preoperatively, only 4th and 6th order aberration had significant correlation with corneal asphericity and apical radius of curvature (p<0.001). Postoperatively, all 3th to 6th order aberrations had statistically significant correlation with corneal asphericity (p<0.01), but only 4th and 6th order aberration had significant correlation with apical radius of curvature (p<0.05). The asymmetrical aberration like coma had significant correlation with vertical offset of pupil center (p<0.01). Preoperatively, corneal aberrations had no significant correlation with visual acuity and area under the log contrast sensitivity (AULCSF) (P>0.05). Postoperatively, corneal aberrations still didn't have significant correlation with visual acuity (P>0.05), but had significantly negative correlation with AULCSF (P<0.01). Corneal asphericity had no significant correlation with AULCSF before and after the treatment (P>0.05). Conclusions: Corneal aberrations had different correlation with corneal profile and visual performance for eyes of virgin myopia and postoperative LASIK, which may be due to changed corneal profile and limitation of metrics of corneal aberrations.
Spaulding, Glen F.; Goodwin, Thomas J.; Aten, Laurie; Prewett, Tacey; Fitzgerald, Wendy S.; OConnor, Kim; Caldwell, Delmar; Francis, Karen M.
Spheroids of corneal tissue about 5 mm in diameter have been grown in a bioreactor from an in vitro culture of primary rabbit corneal cells to illustrate the production of optic cells from aggregates and tissue. In comparison with corneal tissues previously grown in vitro by other techniques, this tissue approximates intact corneal tissue more closely in both size and structure. This novel three-dimensional tissue can be used to model cell structures and functions in normal and abnormal corneas. Efforts continue to refine the present in vitro method into one for producing human corneal tissue to overcome the chronic shortage of donors for corneal transplants: The method would be used to prepare corneal tissues, either from in vitro cultures of a patient s own cells or from a well-defined culture from another human donor known to be healthy. As explained in several articles in prior issues of NASA Tech Briefs, generally cylindrical horizontal rotating bioreactors have been developed to provide nutrient-solution environments conducive to the 30 NASA Tech Briefs, October 2003 growth of delicate animal cells, with gentle, low-shear flow conditions that keep the cells in suspension without damaging them. The horizontal rotating bioreactor used in this method, denoted by the acronym "HARV," was described in "High-Aspect-Ratio Rotating Cell-Culture Vessel" (MSC-21662), NASA Tech Briefs, Vol. 16, No. 5 (May, 1992), page 150.
Uematsu, Masafumi; Mohamed, Yasser Helmy; Onizuka, Naoko; Ueki, Ryotaro; Inoue, Daisuke; Fujikawa, Azusa; Sasaki, Hitoshi; Kitaoka, Takashi
To investigate the corneal toxicity of Xalatan and three latanoprost generics using transepithelial electrical resistance (TER) and scanning electron microscopy (SEM). Corneal TER changes after a 60-s exposure to Xalatan (latanoprost 0.005% preserved with 0.02% BAC), and latanoprost generics (Latanoprost PF BAC free, Latanoprost Nitten SB containing sodium benzoate and Latanoprost Towa containing 0.01% BAC with sodium chloride polysorbate 80 as additive) were measured in living rabbits. Corneal damage was also examined by SEM. Hank's balanced salt solution (HBSS) was used as a control. There was a significant decrease in the corneal TER after exposure of the cornea to Xalatan (p < 0.01) and all latanoprost generics (p < 0.01: Latanoprost PF, p < 0.05: Latanoprost Nitten SB, Latanoprost Towa) as compared to HBSS. All latanoprost generics showed less TER decrease in the corneal TER as compared to Xalatan (p < 0.01). SEM revealed that superficial cells of Xalatan-treated corneas were damaged and exhibited degenerated microvilli. Conversely, the superficial cells of corneas exposed to HBSS or all latanoprost generics appeared normal and had normal microvilli under SEM examinations. The corneal toxicity of Xalatan is greater than that of latanoprost generics. Xalatan contains 0.02% BAC, which may be responsible for the corneal toxicity.
Tsai, Ching-Yao; Woung, Lin-Chung; Yen, Jiin-Cherng; Tseng, Po-Chen; Chiou, Shih-Hwa; Sung, Yen-Jen; Liu, Kuan-Ting; Cheng, Yung-Hsin
Oxidative damage to cornea can be induced by alkaline chemical burn which may cause vision loss or blindness. Recent studies showed that exogenous application of natural antioxidants may be a potential treatment for corneal wound healing. However, low ocular bioavailability and short residence time are the limiting factors of topically administered antioxidants. Ferulic acid (FA) is a natural phenolic compound and an excellent antioxidant. The study was aimed to investigate the effects of FA in corneal epithelial cells (CECs) under oxidative stress and evaluate the feasibility of use the thermosensitive chitosan-based hydrogel containing FA for corneal wound healing. The results demonstrated that post-treatment of FA on CECs could decrease the inflammation-level and apoptosis. In the rabbit corneal alkali burn model, post-treatment FA-loaded hydrogel may promote the corneal wound healing. The results of study suggest that FA-loaded hydrogel may have the potential applications in treating corneal alkali burn.
Chen, Hongbin; Chen, Zhenghua; Xu, Ying
To test the safe clinical application of sufentanil as topical ophthalmic drops by examining treated rabbit eyes for ophthalmic irritation signs or short-time toxic reactions. Twenty-four rabbits were randomly divided into 8 groups (n = 3): The ocular toxicity at 14 d after eye drop ad- ministration was evaluated in groups 1 to 4, and at 30 d post- administration in groups 5 to 8. Groups 1 and 5 were treated with blank vehicle and served as normal controls. The left eyes of rabbits in groups 2 and 6 were exposed to low-dose sufentanil.(5 μg, 2 drops within 5 min), groups 3 and 7 received moderate-dose sufentanil (7.5 μg, 3 drops within 10 min), and groups 4 and 8 received high-dose sufentanil.(10 μg, 4 drops within 15 min). As self-controls, the right eyes of each rabbit were administered an equivalent amount of sodium chloride (9 g/L) at the same drop intervals. At 14 and 30 d after exposure to sufentanil, ophthalmic irritation signs were evaluated and corneas were stained with fluorescein and observed by slit-lamp microscopy. Corneal endothelial counts were performed and toxic reactions were evaluated. Multiple parameters were compared in the control and experimental groups by visual inspection and slit-lamp examination at 14 and 30 d after sufentanil administration. No evidence of irritation signs (including corneal opacity, conjunctival congestion, or edema), eye secretions, iris abnormalities, or temporal eye closure were noted. Corneal en- dothelial cell counts did not significantly differ between the control and experimental groups. Light microscopy revealed no pathological or morphological injury to the cornea, conjunctiva, iris, ciliary body, retina, or optic nerve in either group. The same observation outcomes were noted at 14 and 30 d after administration. Single ocular administration of sufentanil at a dose of 5-10 μg in rabbits yields no ocular irritation or toxic responses at 14 or 30 d following eye drop delivery.
Jordan, Dinah G
When filling prescriptions for a rabbit, it is important to know whether the rabbit is a pet or is being raised as a source of food for human consumption. Several drugs widely used for pet rabbits are prohibited from exralabel use in animals raised for food production. The list of banned drugs should always be perused prior to filling a prescription for a rabbit being raised for food production. Since no veterinary-approved products exist for rabbits and most medications must be compounded, pharmacists are likely to encounter prescriptions for rabbits in their practice. A basic understanding of rabbit anatomy, physiolgy and common diseases will assist pharmacists in distinguishing between safe and dangerous drugs for administration to rabbits.
Jiang, Yan; Fu, Wei-Cai; Zhang, Lin
To explore mechanism of nduction of fibroblast to corneal endothelial cell. Rabbit conjunctiva fibroblasts were used as feeder cells, rabbit oral mucosa epithelial cells were used as seed cells, and human denuded amniotic membrane was used as carrier to establish tissue engineering corneal endothelium. The transformation effect was observed. As concentration of mitomycin C increased, cell survival rate gradually decreased, cell proliferation was obviously inhibited when concentration≥25 μg/mL; 5 days after being treated by 5 μg/mL mitomycin C, cell body was enlarged and extended without cell fusion, however after being treated by 0.5 μg/mL mitomycin C, cell body was significantly proliferated and gradually fused; after 3 weeks of culture, stratified epithelium appeared on rabbit oral mucosa epithelial cells, differentiation layers were 4-5 and were well differentiated, the morphology was similar to corneal endothelial cells; Under electron microscope, surface layer of cells were polygonal, tightly connected to another with microvilli on the border, there was hemidesmosome between basal cells and human denuded amniotic membrane. Fibroblast cells have the potential of multi-directional differentiation, effective induction can promote emergence of intercellular desmosomes between seed cells and emergence of epithelial surface microvilli, and differentiate to the corneal endothelial cell. However, clinical application still needs more research and safety evaluation. Copyright © 2014 Hainan Medical College. Published by Elsevier B.V. All rights reserved.
Lewis, Leroy C.; Trammell, David R.
A disposable rabbit for transferring radioactive samples in a pneumatic transfer system comprises aerated plastic shaped in such a manner as to hold a radioactive sample and aerated such that dissolution of the rabbit in a solvent followed by evaporation of the solid yields solid waste material having a volume significantly smaller than the original volume of the rabbit.
Lewis, L.C.; Trammell, D.R.
A disposable rabbit for transferring radioactive samples in a pneumatic transfer system comprises aerated plastic shaped in such a manner as to hold a radioactive sample and aerated such that dissolution of the rabbit in a solvent followed by evaporation of the solid yields solid waste material having a volume significantly smaller than the original volume of the rabbit.
Zhang, Yan Qing; Zhang, Wen Jie; Liu, Wei; Hu, Xiao Jie; Zhou, Guang Dong; Cui, Lei; Cao, Yilin
Previously, we successfully engineered a corneal stromal layer using corneal stromal cells. However, the limited source and proliferation potential of corneal stromal cells has driven us to search for alternative cell sources for corneal stroma engineering. Based on the idea that the tissue-specific environment may alter cell fate, we proposed that dermal fibroblasts could switch their phenotype to that of corneal stromal cells in the corneal environment. Thus, dermal fibroblasts were harvested from newborn rabbits, seeded on biodegradable polyglycolic acid (PGA) scaffolds, cultured in vitro for 1 week, and then implanted into adult rabbit corneas. After 8 weeks of implantation, nearly transparent corneal stroma was formed, with a histological structure similar to that of its native counterpart. The existence of cells that had been retrovirally labeled with green fluorescence protein (GFP) demonstrated the survival of implanted cells. In addition, all GFP-positive cells that survived expressed keratocan, a specific marker for corneal stromal cells, and formed fine collagen fibrils with a highly organized pattern similar to that of native stroma. However, neither dermal fibroblast-PGA construct pre-incubated in vitro for 3 weeks nor chondrocyte-PGA construct could form transparent stroma. The results demonstrated that neonatal dermal fibroblasts could switch their phenotype in the new tissue environment under restricted conditions. The functional restoration of corneal transparency using dermal fibroblasts suggests that they could be an alternative cell source for corneal stroma engineering.
Ko, Match W L; Dongming Wei; Leung, Christopher K S
Corneal indentation is adapted for the design and development of a characterization method for corneal hysteresis behavior - Corneal Indentation Hysteresis (CIH). Fourteen porcine eyes were tested using the corneal indentation method. The CIH measured in enucleated porcine eyes showed indentation rate and intraocular pressure (IOP) dependences. The CIH increased with indentation rate at lower IOP (<; 25 mmHg) and decreased with indentation rate at higher IOP (> 25 mmHg). The CIH was linear proportional to the IOP within an individual eye. The CIH was positively correlated with the IOP, corneal in-plane tensile stress and corneal tangent modulus (E). A new method based on corneal indentation for the measurement of Corneal Indentation Hysteresis in vivo is developed. To our knowledge, this is the first study to introduce the corneal indentation hysteresis and correlate the corneal indentation hysteresis and corneal tangent modulus.
Becker, Ulrich; Ehrhardt, Carsten; Schneider, Marc; Muys, Leon; Gross, Dorothea; Eschmann, Klaus; Schaefer, Ulrich F; Lehr, Claus-Michael
The purpose of this study was to evaluate the potential value of different epithelial cell culture systems as in vitro models for studying corneal permeability. Transformed human corneal epithelial (HCE-T) cells and Statens Serum Institut rabbit corneal (SIRC) cells were cultured on permeable filters. SkinEthic human corneal epithelium (S-HCE) and Clonetics human corneal epithelium (C-HCE) were received as ready-to-use systems. Excised rabbit corneas (ERCs) and human corneas (EHCs) were mounted in Ussing chambers, and used as references. Barrier properties were assessed by measuring transepithelial electrical resistance, and by determining the apparent permeability of markers with different physico-chemical properties, namely, fluorescein, sodium salt; propranolol hydrochloride; moxaverine hydrochloride; timolol hydrogenmaleate; and rhodamine 123. SIRC cells and the S-HCE failed to develop epithelial barrier properties, and hence were unable to distinguish between the permeation markers. Barrier function and the power to differentiate compound permeabilities were evident with HCE-T cells, and were even more pronounced in the case of C-HCE, corresponding very well with data from ERCs and EHCs. A net secretion of rhodamine 123 was not observed with any of the models, suggesting that P-glycoprotein or similar efflux systems have no significant effects on corneal permeability. Currently available corneal epithelial cell culture systems show differences in epithelial barrier function. Systems lacking functional cell-cell contacts are of limited value for assessing corneal permeability, and should be critically evaluated for other purposes.
Acosta, L; Castro, M; Fernandez, M; Oliveres, E; Gomez-Demmel, E; Tartara, L
To assess the efficacy of platelet rich plasma (PRP) in the treatment of extensive corneal ulcers in albino rabbits. New Zealand rabbits, divided in 3 groups, were used for the study. Corneal ulcers of 10mm diameter were made. Rabbits blood was extracted for the preparation of the PRP of the corresponding group. The blood was processed by differential centrifugation. The first group, named control, was treated with sterile saline every 8h. The second group, named gel, was treated with deproteinized extract gel beef fat every 8h, and the third group, named PRP received one PRP drop on the first and third day of monitoring. The rabbits were monitored, by taking photographs, each day for the 7 days that the study lasted. A better outcome was observed in the group with deproteinized extract gel beef fat (GE group), and the PRP group (PL group), in comparison with the control group (CO group) (P<.05). The PRP showed to be just as effective as the commercial product (Solcoseryl®), for the regeneration of the extensive and deep corneal ulcers. Besides, it stands out as a no surgical procedure is required, and there is easy access, low cost and reduced doses. Copyright © 2013 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.
Raj, K. Mohan; Reddy, P. Arun Subhash; Kumar, Vikram Chella
The corneal arcus consists of cholesterol, phospholipids and triglycerides. As serum triglyceride is one of the accurate of lipid metabolic state, greater importance was given, and it was found to be elevated in 72% of patients and a positive correlation with increasing age. This suggests a strong correlation between impairment of lipid metabolism and incidence of corneal arcus. PMID:26015693
Raj, K Mohan; Reddy, P Arun Subhash; Kumar, Vikram Chella
The corneal arcus consists of cholesterol, phospholipids and triglycerides. As serum triglyceride is one of the accurate of lipid metabolic state, greater importance was given, and it was found to be elevated in 72% of patients and a positive correlation with increasing age. This suggests a strong correlation between impairment of lipid metabolism and incidence of corneal arcus.
Ringvold, Amund; Anderssen, Erlend; Kjønniksen, Inge
To evaluate whether the content of ascorbic acid in the corneal epithelium and aqueous humor reflects seasonal fluctuations in parallel with environmental changes. Reindeer, cattle, rabbits, and humans were examined, to cover a broad spectrum of overlapping habitats. Ascorbic acid was determined by high-performance liquid chromatography. The thickness of the corneal epithelium was measured, and the number of cells was counted in the tissue sections. Three groups of reindeer eyes were used, two of them collected during summer, the third group during winter. Ascorbate content did not show seasonal variation in either the corneal epithelium or the aqueous humor, whereas epithelial thickness and number of cells decreased significantly from summer to winter. In cattle, ascorbate content, thickness of the epithelium, and number of cells were lower in animals tended indoors compared with those tended outdoors, whereas ascorbate level in the aqueous humor remained similar in both cases. The rabbit showed significantly reduced ascorbate content in the corneal epithelium but not in the aqueous humor in tarsorrhaphy-treated eyes. This procedure did not change epithelial thickness, but the number of cells was slightly increased. The mean epithelial thickness in human corneas successively decreased with increasing latitude and decreasing radiation exposure from the summer season in Oslo to the midnight sun, polar night, conditions in Tromsø, 10 degrees far north, although the differences did not reach statistical significance. Ambient radiation is needed to sustain high ascorbic acid concentration in the corneal epithelium. Corneal epithelial thickness and number of cells are prone to seasonal fluctuations regulated by ambient radiation. In contrast, ascorbate content of the aqueous humor is uninfluenced by environmental change. It is suggested that seasonal adaptation of mammalian corneal epithelium in response to variation in ambient radiation may be nature's strategy for
Doss, James D.; Hutson, Richard L.
The disclosure relates to a circulating saline electrode for changing corneal shape in eyes. The electrode comprises a tubular nonconductive electrode housing having an annular expanded base which has a surface substantially matched to a subject corneal surface. A tubular conductive electrode connected to a radiofrequency generating source is disposed within the electrode housing and longitudinally aligned therewith. The electrode has a generally hemispherical head having at least one orifice. Saline solution is circulated through the apparatus and over the cornea to cool the corneal surface while radiofrequency electric current emitted from the electrode flows therefrom through the cornea to a second electrode, on the rear of the head. This current heats the deep corneal stroma and thereby effects corneal reshaping as a biological response to the heat.
Kling, Sabine; Hafezi, Farhad
In recent years, the interest in corneal biomechanics has strongly increased. The material properties of the cornea determine its shape and therefore play an important role in corneal ectasia and related pathologies. This review addresses the molecular origin of biomechanical properties, models for their description, methods for their characterisation, techniques for their modification, and computational simulation approaches. Recent research has focused on developing non-contact techniques to measure the biomechanical properties in vivo, on determining structural and molecular abnormalities in pathological corneas, on developing and optimising techniques to reinforce the corneal tissue and on the computational simulation of surgical interventions. A better understanding of corneal biomechanics will help to improve current refractive surgeries, allow an earlier diagnosis of ectatic disorders and a better quantification of treatments aiming at reinforcing the corneal tissue. © 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists.
Raghunathan, Vijay Krishna; Thomasy, Sara M; Strøm, Peter; Yañez-Soto, Bernardo; Garland, Shaun P; Sermeno, Jasmyne; Reilly, Christopher M; Murphy, Christopher J
Corneal wound healing is an enormously complex process that requires the simultaneous cellular integration of multiple soluble biochemical cues, as well as cellular responses to the intrinsic chemistry and biophysical attributes associated with the matrix of the wound space. Here, we document how the biomechanics of the corneal stroma are altered through the course of wound repair following keratoablative procedures in rabbits. Further we documented the influence that substrate stiffness has on stromal cell mechanics. Following corneal epithelial debridement, New Zealand white rabbits underwent phototherapeutic keratectomy (PTK) on the right eye (OD). Wound healing was monitored using advanced imaging modalities. Rabbits were euthanized and corneas were harvested at various time points following PTK. Tissues were characterized for biomechanics with atomic force microscopy and with histology to assess inflammation and fibrosis. Factor analysis was performed to determine any discernable patterns in wound healing parameters. The matrix associated with the wound space was stiffest at 7days post PTK. The greatest number of inflammatory cells were observed 3days after wounding. The highest number of myofibroblasts and the greatest degree of fibrosis occurred 21days after wounding. While all clinical parameters returned to normal values 400days after wounding, the elastic modulus remained greater than pre-surgical values. Factor analysis demonstrated dynamic remodeling of stroma occurs between days 10 and 42 during corneal stromal wound repair. Elastic modulus of the anterior corneal stroma is dramatically altered following PTK and its changes coincide initially with the development of edema and inflammation, and later with formation of stromal haze and population of the wound space with myofibroblasts. Factor analysis demonstrates strongest correlation between elastic modulus, myofibroblasts, fibrosis and stromal haze thickness, and between edema and central corneal
O'Donnell, Clare; Wolffsohn, James S
To examine the academic literature on the grading of corneal transparency and to assess the potential use of objective image analysis. Reference databases of academic literature were searched and relevant manuscripts reviewed. Annunziato, Efron (Millennium Edition) and Vistakon-Synoptik corneal oedema grading scale images were analysed objectively for relative intensity, edges detected, variation in intensity and maximum intensity. In addition, corneal oedema was induced in one subject using a low oxygen transmissibility (Dk/t) hydrogel contact lens worn for 3h under a light eye patch. Recovery from oedema was monitored over time using ultrasound pachymetry, high and low contrast visual acuity measures, bulbar hyperaemia grading and transparency image analysis of the test and control eyes. Several methods for assessing corneal transparency are described in the academic literature, but none have gained widespread use in clinical practice. The change in objective image analysis with printed scale grade was best described by quadratic parametric or sigmoid 3-parameter functions. 'Pupil image scales' (Annunziato and Vistakon-Synoptik) were best correlated to average intensity; however, the corneal section scale (Efron) was strongly correlated to variations in intensity. As expected, patching an eye wearing a low Dk/t hydrogel contact lens caused a significant (F = 119.2, p < 0.001) 14.3% increase in corneal thickness, which gradually recovered under open eye conditions. Corneal section image analysis was the most affected parameter and intensity variation across the slit width, in isolation, was the strongest correlate, accounting for 85.8% of the variance with time following patching, and 88.7% of the variance with corneal thickness. Corneal oedema is best determined objectively by the intensity variation across the width of a corneal section. This can be easily measured using a slit-lamp camera connected to a computer. Oedema due to soft contact lens wear is not
Kusano, Mao; Uematsu, Masafumi; Kumagami, Takeshi; Sasaki, Hitoshi; Kitaoka, Takashi
We evaluated acute changes in corneal barrier function after instillation with preservatives using corneal transepithelial electric resistance (TER) in vivo and cytotoxicity tests in vitro. The corneal TER of live rabbits was measured using a volt-ohm meter and silver/silver chloride electrodes. The cornea was exposed to the preservatives benzalkonium chloride (BAC; 0.001%, 0.002%, 0.005%, 0.01%, and 0.02%), 0.04% paraben, 0.5% chlorobutanol, 0.005% chlorhexidine digluconate, 2% boric acid, and 0.01% ethylenediaminetetraacetic acid, and then changes in the TER were monitored for 60 seconds. Cultured normal rabbit corneal epithelial cells were exposed to the same preservatives for 60 seconds in vitro, and cell viability was evaluated using the WST-1 assay. The TER instantly decreased and became significantly lower than the control within 10 seconds after instillation with 0.01% and 0.02% BAC (P < 0.01) and within 60 seconds after that with 0.005% BAC (P < 0.01). The TER decreased concomitantly with increasing BAC concentration. Cell viability after instillation with 0.005%, 0.01%, and 0.02% BAC for 60 seconds was significantly lower than that of the control (P < 0.0001). None of the other preservatives significantly altered the TER or cell viability. Decreases in the TER correlated with cell viability (r = 0.94, P < 0.0001). Instillation with BAC immediately disrupted the corneal epithelium. Corneal epithelial cell death is supposed to be associated with a decline in barrier function; thus, corneal TER measurement in vivo can assess the acute toxicity of preservatives added to ophthalmic drugs.
Bloom, D C; Devi-Rao, G B; Hill, J M; Stevens, J G; Wagner, E K
Infectious virus assays and PCR amplification of DNA and RNA were used to investigate herpes simplex virus (HSV) DNA replication and gene expression in the rabbit corneal model for virus reactivation in vivo. We used carefully defined latency-associated transcript-negative (LAT-) and LAT+ promoter mutants of the 17syn+ strain of HSV type 1. In agreement with earlier studies using a more extensive LAT- deletion mutant, the 17 delta Pst(LAT-) virus reactivated with extremely low frequency upon epinephrine induction. In contrast to our findings with murine latency models, amounts of viral DNA recovered from rabbit ganglia latently infected with either LAT+ or LAT- virus were equivalent. Also in contrast with the murine models, no net increase in viral DNA was seen in latently infected rabbit trigeminal ganglia induced to reactivate in vivo by iontophoresis of epinephrine. Despite this, transcription of lytic-phase genes could be detected within 4 h following induction of rabbits latently infected with either LAT+ or LAT- virus; this transcription diminished by 16 h following induction. These results are discussed in relation to models for the mechanism of action of HSV LAT. Images PMID:8107194
Kim, Mee Kum; Hara, Hidetaka
Corneal allo-transplantation is a well-established technique to treat corneal blindness. However, the limited availability of human donors demands the exploration of alternative treatments such as corneal xenotransplantation (e.g., pigs as donors) and bioengineered corneas. Since the first attempt of corneal xenotransplantation using a donor pig cornea in 1844, great advances have been made in the development of genetically-engineered pigs, effective immunosuppressive protocols and the establishment of guidelines for the conduction of clinical trials. We highlight immunological and physio-anatomical barriers of corneal xenotransplantation, recent progress of corneal xenotransplantation in non-human-primates studies, and regulatory guidelines to conduct clinical trials for corneal xenotransplantation.
Phu, Donna; Wray, Lindsay S; Warren, Robert V; Haskell, Richard C; Orwin, Elizabeth J
Corneal blindness is a significant problem treated primarily by corneal transplants. Donor tissue supply is low, creating a growing need for an alternative. A tissue-engineered cornea made from patient-derived cells and biopolymer scaffold materials would be widely accessible to all patients and would alleviate the need for donor sources. Previous work in this lab led to a method for electrospinning type I collagen scaffolds for culturing corneal fibroblasts ex vivo that mimics the microenvironment in the native cornea. This electrospun scaffold is composed of small-diameter, aligned collagen fibers. In this study, we investigate the effect of scaffold nanostructure and composition on the phenotype of corneal stromal cells. Rabbit-derived corneal fibroblasts were cultured on aligned and unaligned collagen type I fibers ranging from 50 to 300 nm in diameter and assessed for expression of α-smooth muscle actin, a protein marker upregulated in hazy corneas. In addition, the optical properties of the cell-matrix constructs were assessed using optical coherence microscopy. Cells grown on collagen scaffolds had reduced myofibroblast phenotype expression compared to cells grown on tissue culture plates. Cells grown on aligned collagen type I fibers downregulated α-smooth muscle actin protein expression significantly more than unaligned collagen scaffolds, and also exhibited reduced overall light scattering by the tissue construct. These results suggest that aligned collagen type I fibrous scaffolds are viable platforms for engineering corneal replacement tissue.
Goswami, Dinesh G.; Tewari-Singh, Neera; Agarwal, Rajesh
The vesicating agents sulfur mustard (SM) and lewisite (LEW) are potent chemical warfare agents that primarily cause damage to the ocular, skin, and respiratory systems. However, ocular tissue is the most sensitive organ, and vesicant exposure results in a biphasic injury response, including photophobia, corneal lesions, corneal edema, ulceration, and neovascularization, and may cause loss of vision. There are several reports on ocular injury from exposure to SM, which has been frequently used in warfare. However, there are very few reports on ocular injury by LEW, which indicate that injury symptoms appear instantly after exposure and faster than SM. In spite of extensive research efforts, effective therapies for vesicant-induced ocular injuries, mainly to the most affected corneal tissue, are not available. Hence, we have established primary human corneal epithelial (HCE) cells and rabbit corneal organ culture models with the SM analog nitrogen mustard (NM), which have helped to test the efficacy of potential therapeutic agents. These agents will then be further evaluated against in vivo SM- and LEW-induced corneal injury models, which will assist in the development of potential broad-spectrum therapies against vesicant-induced ocular injuries. PMID:27327041
Li, Naiyang; Wang, Xiaoran; Wan, Pengxia; Huang, Minghai; Wu, Zheng; Liang, Xuanwei; Liu, Ying; Ge, Jian; Huang, Junqi; Wang, Zhichong
Tectonic lamellar keratoplasty (TLKP) is a primary surgical procedure to improve the condition of the recipient bed in high-risk corneal transplantation. It is usually performed for a secondary optical penetrating keratoplasty (PKP). The present study was undertaken to explore a new strategy for TLKP using acellular corneal stroma (ACS) prepared by decellularization. ACS for TLKP was prepared from cat cornea by decellularization. The efficiency of the decellularization was examined by hematoxylin and eosin (H&E) staining and through DNA content analysis. Twenty-eight New Zealand white rabbits, as recipients, were assigned to one of two groups that had different material for their TLKP. The TLKP was combined with a central optical PKP as a single-stage procedure. Either ACS or fresh cat corneal lamella, 11.25 mm in diameter, was used for the TLKP in these two groups. After TLKP, a 6.5-mm full-thickness cat cornea was placed in the central cornea of each recipient rabbit for PKP. Clinical outcomes and the histology of the transplants were compared post-operatively. ACS for TLKP prolonged the survival of the transplants. The mean survival time of the transplants in the ACS group (36.4±4.3 days) was longer than for those in the control group (14.0±2.2 days, p<0.05). The ACS group showed a significantly smaller neovascularization area compared to the control group. The areas of corneal neovascularization were 5.3±1.1 mm² and 45.2±4.9 mm² (p<0.05), respectively, after two weeks, and 25.1±4.7 mm² and 105.3±12.4 mm² (p<0.05), respectively, after four weeks. Histology revealed that fewer inflammatory cells were infiltrating the transplants in the ACS group than those in the control group. The use of ACS for TLKP prolonged the survival of corneal transplants, reduced corneal neovascularization, and prevented from infiltration of inflammatory cells. It is a feasible and effective strategy to prolong the survival of transplants in high-risk corneal transplantation.
Lamm, Vladimir; Hara, Hidetaka; Mammen, Alex; Dhaliwal, Deepinder; Cooper, David K C
Approximately 39 million people are blind worldwide, with an estimated 285 million visually impaired. The developing world shoulders 90% of the world's blindness, with 80% of causative diseases being preventable or treatable. Blindness has a major detrimental impact on the patient, community, and healthcare spending. Corneal diseases are significant causes of blindness, affecting at least 4 million people worldwide. The prevalence of corneal disease varies between parts of the world. Trachoma, for instance, is the second leading cause of blindness in Africa, after cataracts, but is rarely found today in developed nations. When preventive strategies have failed, corneal transplantation is the most effective treatment for advanced corneal disease. The major surgical techniques for corneal transplantation include penetrating keratoplasty (PK), anterior lamellar keratoplasty, and endothelial keratoplasty (EK). Indications for corneal transplantation vary between countries, with Fuchs' dystrophy being the leading indication in the USA and keratoconus in Australia. With the exception of the USA, where EK will soon overtake PK as the most common surgical procedure, PK is the overwhelming procedure of choice. Success using corneal grafts in developing nations, such as Nepal, demonstrates the feasibility of corneal transplantation on a global scale. The number of suitable corneas from deceased human donors that becomes available will never be sufficient, and so research into various alternatives, for example stem cells, amniotic membrane transplantation, synthetic and biosynthetic corneas, and xenotransplantation, is progressing. While each of these has potential, we suggest that xenotransplantation holds the greatest potential for a corneal replacement. With the increasing availability of genetically engineered pigs, pig corneas may alleviate the global shortage of corneas in the near future.
Lamm, Vladimir; Hara, Hidetaka; Mammen, Alex; Dhaliwal, Deepinder; Cooper, David K.C.
Approximately 39 million people are blind worldwide, with an estimated 285 million visually impaired. The developing world shoulders 90% of the world’s blindness, with 80% of causative diseases being preventable or treatable. Blindness has a major detrimental impact on the patient, community, and healthcare spending. Corneal diseases are significant causes of blindness, affecting at least 4 million people worldwide. The prevalence of corneal disease varies among parts of the world. Trachoma, for instance, is the second leading cause of blindness in Africa, after cataracts, but is rarely found today in developed nations. When preventive strategies have failed, corneal transplantation is the most effective treatment for advanced corneal disease. The major surgical techniques for corneal transplantation include penetrating keratoplasty (PK), anterior lamellar keratoplasty (ALK), and endothelial keratoplasty (EK). Indications for corneal transplantation vary among countries, with Fuchs’ dystrophy being the leading indication in the U.S. and keratoconus in Australia. With the exception of the US, where EK will soon overtake PK as the most common surgical procedure, PK is the overwhelming procedure of choice. Success using corneal grafts in developing nations, such as Nepal, demonstrates the feasibility of corneal transplantation on a global scale. The number of suitable corneas from deceased human donors that becomes available will never be sufficient, and so research into various alternatives, e.g., stem cells, amniotic membrane transplantation, synthetic and biosynthetic corneas, and xenotransplantation, is progressing. While each of these has potential, we suggest that xenotransplantation holds the greatest potential for a corneal replacement. With the increasing availability of genetically-engineered pigs, pig corneas may alleviate the global shortage of corneas in the near future. PMID:25268248
Beutelspacher, Sven Christoph; Ardjomand, Navid; Tan, Peng Hong; Patton, Gillian Sarah; Larkin, D Frank P; George, Andrew J T; McClure, Myra O
In this study we compare the ability of self-inactivating Human Immunodeficiency Virus 1 (HIV-1) and Equine Infectious Anaemia Virus (EIAV)-based vectors to mediate gene transfer to rabbit and human corneas and to a murine corneal endothelial cell line. Both vectors were pseudotyped with vesicular stomatitis virus-G (VSV-G) envelope and contained marker transgenes under the control of an internal CMV promoter. For specificity of action, the heterologous promoter in the EIAV-vector was exchanged for an inducible E-Selectin promoter, previously shown to regulate gene-expression in a plasmid system. We show that EIAV is more efficient than HIV in transducing human and rabbit corneal endothelial cells. Rabbit corneal endothelial cells are transduced in higher quantity than human corneal endothelial cells. In the inducible system, however, we detected impairment between the vector and its internal E-Selectin promoter. Instead of controlled transgene expression or silencing of promoter activity, the U3-modified long-terminal-repeats (LTR) impaired the conditional activity of the E-Selectin promoter. Significant transgene expression was seen without stimulation of the inducible promoter. We show efficient transduction by lentiviruses of a corneal endothelial cell line and of full thickness corneas from different species, confirming that those vectors would be appropriate tools for gene therapy of selected corneal diseases. However, the modification within the U3-LTR did not adequately allow regulated transgene expression. These findings have important implications for vector design for diagnostic or therapeutic opportunities.
Colombres, Gustavo A; Gramajo, Ana L; Arrambide, Maria P; Juarez, Silvina M; Arevalo, J Fernando; Bar, Jorge; Juarez, Claudio P; Luna, Jose D
Purpose To report corneal epithelial defects (CEDs) and delayed epithelial healing after intravitreal bevacizumab (IVB) injection and to describe delayed corneal epithelial healing with topical administration of bevacizumab in an experimental rabbit model. Methods A retrospective chart review was performed on 850 eyes of 850 patients with neovascular eye disease and diabetic macular edema who had received 1.25 to 2.5 mg IVB. In the experimental arm of the study, photorefractive keratectomy was used to create a 3 mm CED in the right eyes of 18 New Zealand rabbits which were then randomized to three equal groups. All rabbits received topical antibiotics, additionally those in group A received topical bevacizumab and animals in group B were treated with topical corticosteroids. The rate of epithelial healing was assessed at different time points using slitlamp photography. Results In the clinical study, seven eyes of seven subjects developed CEDs the day after IVB injection. All of these eyes had preexisting corneal edema. The healing period ranged from 3 to 38 days (average 11 days) despite appropriate medical management. In the experimental study, topical bevacizumab and corticosteroids both significantly hindered corneal epithelial healing at 12 and 24 hours. Conclusion Bevacizumab was demonstrated to cause CEDs in clinical settings. Moreover, corneal epithelial healing was delayed by topical application of bevacizumab, in the experimental model. These short-term results suggest that corneal edema may be considered as a risk factor for epithelial defects after IVB. PMID:22454702
Krachmer, J H
Pellucid marginal degeneration of the cornea is a bilateral, clear, inferior, peripheral corneal-thinning disorder. Protrusion of the cornea occurs above a band of thinning, which is located 1 to 2 mm from the limbus and measures 1 to 2 mm in width. American ophthalmologists are generally not familiar with the condition because most of the literature concerning pellucid degeneration is European. Four cases are described. This condition is differentiated from other noninflammatory cornel-thinning disorders such as keratoconus, keratoglobus, keratotorus, and posterior keratoconus. It is also differentiated from peripheral corneal disorders associated with inflammation such as Terrien's peripheral corneal degeneration, Mooren's ulcers, and ulcers from connective tissue disease.
Zhou, Hong-Yan; Hao, Ji-Long; Bi, Miao-Miao; Wang, Shuang; Zhang, Hong; Zhang, Wen-Song
AIM Excessive dissolve of corneal tissue induced by MMPs which were activated by cytokins and chemokines will lead to corneal ulcer. The molecular mechanism of Lipoxin A4 (LXA4) on corneal collagen degradation in three dimensions was investigated. METHODS Rabbit corneal fibroblasts were harvested and suspended in serum-free MEM. Type I collagen, DMEM, collagen reconstitution buffer and corneal fibroblast suspension were mixed on ice. The resultant mixture solidified in an incubator, after which test reagents and plasminogen was overlaid and the cultures were returned to the incubator. The supernatants from collagen gel incubations were collected and the amount of hydroxyproline in the hydrolysate was measured. Immunoblot analysis of MMP-1, -3 and TMMP-1,-2 was performed. MMP-2,-9 was detected by the method of Gelatin zymography. Cytotoxicity assay was measured. RESULTS LXA4 inhibited corneal collagen degradation in a dose and time manner. LXA4 inhibited the IL-1β induced increases in the pro-MMP-1, -2, -3, -9 and active MMP-1, -2, -3, -9 in a concentration dependent manner. LXA4 could also inhibit the IL-1β induced increases in TIMP-1, -2. CONCLUSION As a potent anti-inflammation reagent, LXA4 can inhibit corneal collagen degradation induced by IL-1β in corneal fibroblasts thus inhibiting corneal dissolving pathology process. PMID:23550231
Hull, D.S.; Riley, M.V.; Csukas, S.; Green, K.
Rabbit corneal endothelial cells perfused with 5 X 10(-6)M rose bengal and exposed to incandescent light demonstrated no alteration of either total of or percent oxidized glutathione after 1 hr. Addition of 5400 U/ml catalase to the perfusing solution had no effect on total glutathione levels but caused a marked reduction in percent oxidized glutathione in corneas exposed to light as well as in those not exposed to light. Substitution of sucrose for glucose in the perfusing solution had no effect on total or percent oxidized glutathione. Perfusion of rabbit corneal endothelium with 0.5 mM chlorpromazine and exposure to ultraviolet (UV) light resulted in no change in total glutathione content. A marked reduction in percent oxidized glutathione occurred, however, in corneas perfused with 0.5 mM chlorpromazine both in the presence and absence of UV light. It is concluded that photodynamically induced swelling of corneas is not the result of a failure of the glutathione redox system.
Kaur, Harmeet; Chaurasia, Shyam S.; de Medeiros, Fabricio W.; Agrawal, Vandana; Salomao, Marcella Q.; Singh, Nirbhai; Ambati, Balamurali K.; Wilson, Steven E.
Myofibroblast development and haze generation in the corneal stroma is mediated by cytokines, including transforming growth factor beta (TGF β), and possibly other cytokines. This study examined the effects of stromal PDGF-β blockade on the development of myofibroblasts in response to -9.0 diopter photorefractive keratectomy in the rabbit. Rabbits that had haze generating photorefractive keratectomy (PRK, for 9 diopters of myopia) in one eye were divided into three different groups: stromal application of plasmid pCMV.PDGFRB.23KDEL expressing a subunit of PDGF receptor b (domains 2-3, which bind PDGF-B), stromal application of empty plasmid pCMV, or stromal application of balanced salt solution (BSS). The plasmids (at a concentration 1000 ng/μl) or BSS was applied to the exposed stroma immediately after surgery and every 24 hours for 4-5 days until the epithelium healed. The group treated with pCMV.PDGFRB.23KDEL showed lower αSMA+ myofibroblast density in the anterior stroma compared to either control group (P≤ 0.001). Although there was also lower corneal haze at the slit lamp at one month after surgery, the difference in haze after PDGF-B blockade was not statistically significant compared to either control group. Stromal PDGF-B blockade during the early postoperative period following PRK decreases stromal αSMA+ myofibroblast generation. PDGF is an important modulator of myofibroblast development in the cornea. PMID:19133260
Liu, G S; Trope, G E; Basu, P K
Beta blockers inhibit corneal re-epithelialization. This may be due to beta-2 receptor controlled mechanisms. To investigate this possibility we performed a randomized, double-masked study involving 60 rabbit iatrogenic induced corneal ulcers produced with iodine vapour. Two beta specific drug compounds were tested, namely, betaxolol hydrochloride 0.25% (Alcon) (beta 1) and L132-468 (Sandoz, Basel) 0.25% (beta 2), and phosphate-buffered solution (PBS) as control. There was no statistical difference in the wound healing rates among all groups at 24 hours but there were significant differences at 48 hours (p less than 0.01). At 72 hours, the L132-468 treated groups showed significantly less healing than the betaxolol hydrochloride treated group. The PBS-treated group was healed at this time. By 20th post burning day, SEM revealed that betaxolol hydrochloride treated corneas were completely healed with normal epithelial microvilli. The L132-468 treated corneas were also healed but desquamation and abnormal cells were observed. In conclusion, beta-2 blockers inhibit corneal re-epithelialization more potently than beta-1 blockers.
Cejka, Cestmir; Holan, Vladimir; Trosan, Peter; Zajicova, Alena; Javorkova, Eliska; Cejkova, Jitka
The aim of this study was to examine whether mesenchymal stem cells (MSCs) and/or corneal limbal epithelial stem cells (LSCs) influence restoration of an antioxidant protective mechanism in the corneal epithelium and renewal of corneal optical properties changed after alkali burns. The injured rabbit corneas (with 0.25 N NaOH) were untreated or treated with nanofiber scaffolds free of stem cells, with nanofiber scaffolds seeded with bone marrow MSCs (BM-MSCs), with adipose tissue MSCs (Ad-MSCs), or with LSCs. On day 15 following the injury, after BM-MSCs or LSCs nanofiber treatment (less after Ad-MSCs treatment) the expression of antioxidant enzymes was restored in the regenerated corneal epithelium and the expressions of matrix metalloproteinase 9 (MMP9), inducible nitric oxide synthase (iNOS), α-smooth muscle actin (α-SMA), transforming growth factor-β1 (TGF-β1), and vascular endothelial factor (VEGF) were low. The central corneal thickness (taken as an index of corneal hydration) increased after the injury and returned to levels before the injury. In injured untreated corneas the epithelium was absent and numerous cells revealed the expressions of iNOS, MMP9, α-SMA, TGF-β1, and VEGF. In conclusion, stem cell treatment accelerated regeneration of the corneal epithelium, restored the antioxidant protective mechanism, and renewed corneal optical properties. PMID:27057279
Nearsightedness surgery - discharge; Refractive surgery - discharge; LASIK - discharge; PRK - discharge ... You had refractive corneal surgery to help improve your vision. This surgery uses a laser to reshape your cornea. It corrects mild-to-moderate nearsightedness, ...
Elhalis, Hussain; Azizi, Behrooz; Jurkunas, Ula V.
Fuchs endothelial corneal dystrophy (FECD) is characterized by progressive loss of corneal endothelial cells, thickening of Descement’s membrane and deposition of extracellular matrix in the form of guttae. When the number of endothelial cells becomes critically low, the cornea swells and causes loss of vision. The clinical course of FECD usually spans 10–20 years. Corneal transplantation is currently the only modality used to restore vision. Over the last several decades genetic studies have detected several genes, as well as areas of chromosomal loci associated with the disease. Proteomic studies have given rise to several hypotheses regarding the pathogenesis of FECD. This review expands upon the recent findings from proteomic and genetic studies and builds upon recent advances in understanding the causes of this common corneal disorder. PMID:20964980
... ency/presentations/100082.htm Corneal transplant - series—Normal anatomy To use the sharing features on this page, ... Bethesda, MD 20894 U.S. Department of Health and Human Services National Institutes of Health Page last updated: ...
Denis, Heidi M
Corneal disease is common in equine ophthalmology and requires vigilant monitoring and appropriate therapy to optimize the outcome. Many equine corneal diseases, particularly those that progress rapidly, may benefit from surgical intervention. These include descemetoceles, deep corneal lacerations and ulcers, corneal perforation/iris prolapse, ulcerative keratitis, corneal stromal abscesses, and corneoscleral neoplasia. Indications for corneal transplantation include optical, tectonic, therapeutic, and cosmetic purposes. Corneal transplantation is most often implemented in equine patients for tectonic and therapeutic reasons when a cornea is compromised by corneal stromal abscess, iris prolapse, or neoplasia. This article provides an outline of when to consider surgical intervention for corneal disease, the procedures available and expected outcomes, and how appropriate early surgical intervention can dramatically improve the end result.
Lai, Jui-Yang; Cheng, Hsiao-Yun; Ma, David Hui-Kang
Hyaluronic acid (HA) is a linear polysaccharide naturally found in the eye and therefore is one of the most promising biomaterials for corneal endothelial regenerative medicine. This study reports, for the first time, the development of overrun-processed porous HA hydrogels for corneal endothelial cell (CEC) sheet transplantation and tissue engineering applications. The hydrogel carriers were characterized to examine their structures and functions. Evaluations of carbodiimide cross-linked air-dried and freeze-dried HA samples were conducted simultaneously for comparison. The results indicated that during the fabrication of freeze-dried HA discs, a technique of introducing gas bubbles in the aqueous biopolymer solutions can be used to enlarge pore structure and prevent dense surface skin formation. Among all the groups studied, the overrun-processed porous HA carriers show the greatest biological stability, the highest freezable water content and glucose permeability, and the minimized adverse effects on ionic pump function of rabbit CECs. After transfer and attachment of bioengineered CEC sheets to the overrun-processed HA hydrogel carriers, the therapeutic efficacy of cell/biopolymer constructs was tested using a rabbit model with corneal endothelial dysfunction. Clinical observations including slit-lamp biomicroscopy, specular microscopy, and corneal thickness measurements showed that the construct implants can regenerate corneal endothelium and restore corneal transparency at 4 weeks postoperatively. Our findings suggest that cell sheet transplantation using overrun-processed porous HA hydrogels offers a new way to reconstruct the posterior corneal surface and improve endothelial tissue function. PMID:26296087
Marcos, Susana; Requejo-Isidro, Jose; Merayo-Lloves, Jesus; Acuña, A. Ulises; Hornillos, Valentin; Carrillo, Eugenia; Pérez-Merino, Pablo; del Olmo-Aguado, Susana; del Aguila, Carmen; Amat-Guerri, Francisco; Rivas, Luis
Acanthamoeba keratitis is a serious pathogenic corneal disease, with challenging diagnosis. Standard diagnostic methods include corneal biopsy (involving cell culture) and in vivo reflection corneal microscopy (in which the visualization of the pathogen is challenged by the presence of multiple reflectance corneal structures). We present a new imaging method based on fluorescence sectioned microscopy for visualization of Acanthamoeba. A fluorescent marker (MT-11-BDP), composed by a fluorescent group (BODIPY) inserted in miltefosine (a therapeutic agent against Acanthamoeba), was developed. A custom-developed fluorescent structured illumination sectioned corneal microscope (excitation wavelength: 488 nm; axial/lateral resolution: 2.6 μm/0.4-0.6 μm) was used to image intact enucleated rabbit eyes, injected with a solution of stained Acanthamoeba in the stroma. Fluorescent sectioned microscopic images of intact enucleated rabbit eyes revealed stained Acanthamoeba trophozoites within the stroma, easily identified by the contrasted fluorescent emission, size and shape. Control experiments show that the fluorescent maker is not internalized by corneal cells, making the developed marker specific to the pathogen. Fluorescent sectioned microscopy shows potential for specific diagnosis of Acanthamoeba keratitis. Corneal confocal microscopy, provided with a fluorescent channel, could be largely improved in specificity and sensitivity in combination with specific fluorescent marking. PMID:23082290
Fielder, A R; Winder, A F; Sheraidah, G A; Cooke, E D
Corneal arcus presents many puzzling features. The correlation between its incidence and serum lipid levels is poor and, using immunoelectrophoresis, we have only been able to identify low-density lipoprotein inconsistently in corneae containing this deposition. Infrared thermography has shown us that arcus commences in the warmest regions of the cornea. We have considered the possible relevance of our biochemical and thermographic findings to other problems with corneal arcus such as its irreversibility, anatomical distribution, and clear zone.
Gao, Feng; Lin, Tao; Pan, Yingzhe
Diabetic keratopathy is an ocular complication that occurs with diabetes. In the present study, the effect of diabetic keratopathy on corneal optical density, central corneal thickness, and corneal endothelial cell count was investigated. One hundred and eighty diabetic patients (360 eyes) were enrolled in the study during the period from March, 2012 to March, 2013. The patients were divided into three age groups: <5, 5-10 and >10 years, with 60 patients per group (120 eyes). During the same period, 60 healthy cases (120 eyes) were selected and labeled as the normal control group. The Pentacam was used to measure the corneal optical density, and central corneal thickness. Specular microscopy was used to examine the corneal endothelial cell density. The coefficient of partial correlation was used to control age and correlate the analysis between the corneal optical density, corneal endothelial cell density, and central corneal thickness. The stage of the disease, the medial and intimal corneal optical density and central corneal thickness was analyzed in the diabetes group. The corneal optical density in the diabetes group increased compared with that of the normal control group. The medial and intimal corneal optical density and central corneal thickness were positively correlated with the course of the disease. However, the corneal endothelial cell density was not associated with the course of diabetes. There was a positive association between the medial and intimal corneal optical density and central corneal thickness of the diabetic patients. In conclusion, the results of the present study show that medial and intimal corneal optical density and central corneal thickness were sensitive indicators for early diabetic keratopathy.
Gao, Feng; Lin, Tao; Pan, Yingzhe
Diabetic keratopathy is an ocular complication that occurs with diabetes. In the present study, the effect of diabetic keratopathy on corneal optical density, central corneal thickness, and corneal endothelial cell count was investigated. One hundred and eighty diabetic patients (360 eyes) were enrolled in the study during the period from March, 2012 to March, 2013. The patients were divided into three age groups: <5, 5–10 and >10 years, with 60 patients per group (120 eyes). During the same period, 60 healthy cases (120 eyes) were selected and labeled as the normal control group. The Pentacam was used to measure the corneal optical density, and central corneal thickness. Specular microscopy was used to examine the corneal endothelial cell density. The coefficient of partial correlation was used to control age and correlate the analysis between the corneal optical density, corneal endothelial cell density, and central corneal thickness. The stage of the disease, the medial and intimal corneal optical density and central corneal thickness was analyzed in the diabetes group. The corneal optical density in the diabetes group increased compared with that of the normal control group. The medial and intimal corneal optical density and central corneal thickness were positively correlated with the course of the disease. However, the corneal endothelial cell density was not associated with the course of diabetes. There was a positive association between the medial and intimal corneal optical density and central corneal thickness of the diabetic patients. In conclusion, the results of the present study show that medial and intimal corneal optical density and central corneal thickness were sensitive indicators for early diabetic keratopathy. PMID:27588090
Kimura, Kazuhiro; Zhou, Hongyan; Orita, Tomoko; Kobayashi, Shinya; Wada, Tomoyuki; Nakamura, Yoshikuni; Nishida, Teruo; Sonoda, Koh-Hei
We examined the effect of all-trans retinoic acid on collagen degradation mediated by corneal fibroblasts. Rabbit corneal fibroblasts were cultured with or without all-trans retinoic acid in a three-dimensional collagen gel, and the extent of collagen degradation was determined by measurement of hydroxyproline in acid hydrolysates of culture supernatants. Matrix metalloproteinase expression was examined by immunoblot analysis and gelatin zymography. The abundance and phosphorylation state of the endogenous nuclear factor-kappaB inhibitor IκB-α were examined by immunoblot analysis. Corneal ulceration was induced by injection of lipopolysaccharide into the central corneal stroma of rabbits and was assessed by observation with a slitlamp microscope. All-trans retinoic acid inhibited interleukin-1β-induced collagen degradation by corneal fibroblasts in a concentration- and time-dependent manner. It also attenuated the release and activation of matrix metalloproteinases as well as the phosphorylation and degradation of IκB-α induced by interleukin-1β in these cells. Topical application of all-trans retinoic acid suppressed corneal ulceration induced by injection of lipopolysaccharide into the corneal stroma. All-trans retinoic acid inhibited collagen degradation mediated by corneal fibroblasts exposed to interleukin-1β, with this effect being accompanied by suppression of nuclear factor-kappaB signalling as well as of matrix metalloproteinase release and activation in these cells. All-trans retinoic acid also attenuated lipopolysaccharide-induced corneal ulceration in vivo. Our results therefore suggest that all-trans retinoic acid might prove effective for the treatment of patients with corneal ulceration. © 2016 Royal Australian and New Zealand College of Ophthalmologists.
Teoh, Stephen C B; Lee, Jong-Jian; Fam, Han-Bor
We report the complications and management of a retained bee sting injury to the cornea. The case highlights the acute and chronic management of an uncommon injury and its pathogenesis. A 67-year-old man was attacked by a swarm of bees and was referred for severe chemosis on the right eye. A retained corneal bee stinger (ovipositor) was seen but removal was only partially successful. He subsequently developed a large corneal epithelial defect, anterior uveitis, intractable glaucoma, traumatic cataract, toxic optic neuropathy, and corneal scarring. We reviewed the literature on corneal bee sting injuries and their complications. Inflammation was controlled with topical steroids and the patient underwent a combined phacoemulsification and trabeculectomy with mitomycin-C for uncontrolled glaucoma. However, optic neuropathy did not resolve. Corneal bee sting injuries are uncommon but can result in severe sight-threatening complications such as toxic optic neuropathy. Early recognition of the possible complications and appropriate treatment may help to prevent permanent loss of vision. Removal of a retained corneal bee stinger remains controversial.
Swinger, C A; Kornmehl, E W; York, S; Forman, J S
A corneal mold is described that provides an MK corneal button of normal thickness and curvature from an edematous, post-mortem button. The uniform, processed tissue can then be used for experimental refractive surgery.
Lanza, Michele; Cennamo, Michela; Iaccarino, Stefania; Irregolare, Carlo; Bifani, Mario; Gironi Carnevale, Ugo Antonello
This study was designed to evaluate the correlation between corneal biomechanical and morphological data in healthy eyes, eyes that underwent myopic photorefractive keratectomy (PRK), keratoconus affected eyes, and keratoconus affected eyes that underwent corneal collagen crosslinking (CCC). Complete clinical eye examination of all eyes was followed by tomographic (Pentacam, Oculus, Wetzlar, Germany) and biomechanical (Corvis ST, Oculus, Wetzlar, Germany) evaluation. Differences among Corvis ST (CST) parameters in the different groups have been performed. Linear regression between central corneal thickness (CCT), intraocular pressure (IOP), and anterior corneal curvature measured with Sim'K (KM), versus corneal deformation parameters measured with Corvis ST in the different groups, has been run using SPSS software version 18.0. We evaluated 64 healthy eyes of 64 patients with a mean refractive error of −0.65 ± 1.68 D (measured as spherical equivalent), 17 eyes of 17 patients that underwent myopic PRK for a mean refractive defect of −4.91 ± 2.05 D (measured as spherical equivalent), 16 eyes of 16 patients affected by keratconus (stage 2-3 of Amsler Classification), and 13 eyes of 13 patients affected by keratoconus that underwent CCC. Our data suggest that corneal curvature would have a greater influence on corneal deformation than CCT; in fact KM values are more strongly associated with more CST parameters both about corneal change in shape and both about the corneal ability to come back at original shape. PMID:25054144
Thomasy, Sara M.; Krishna Raghunathan, Vijay; Winkler, Moritz; Reilly, Christopher M.; Sadeli, Adeline R.; Russell, Paul; Jester, James V.; Murphy, Christopher J.
The rabbit is commonly used to evaluate new corneal prosthetics and study corneal wound healing. Knowledge of the stiffness of the rabbit cornea would better inform design and fabrication of keratoprosthetics and substrates with relevant mechanical properties for in vitro investigations of corneal cellular behavior. This study determined the elastic modulus of the rabbit corneal epithelium, anterior basement membrane (ABM), anterior and posterior stroma, Descemet’s membrane (DM) and endothelium using atomic force microscopy (AFM). In addition, three-dimensional collagen fiber organization of the rabbit cornea was determined using nonlinear optical high-resolution macroscopy. Elastic modulus as determined by AFM for each corneal layer was: epithelium 0.57 ± 0.29 kPa (mean ± SD), ABM 4.5 ± 1.2 kPa, anterior stroma 1.1 ± 0.6 kPa, posterior stroma 0.38 ± 0.22 kPa, DM 11.7 ± 7.4 kPa, and endothelium 4.1 ± 1.7 kPa. Biophysical properties, including elastic modulus, are unique for each layer of the rabbit cornea and are dramatically softer in comparison to the corresponding regions of the human cornea. Collagen fiber organization is also dramatically different between the two species with markedly less intertwining observed in the rabbit versus human cornea. Given that substratum stiffness considerably alters corneal cell behavior, keratoprosthetics that incorporate mechanical properties simulating the native human cornea may not elicit optimal cellular performance in rabbit corneas that have dramatically different elastic moduli. These data will allow for the design of substrates that better mimic the biomechanical properties of the corneal cellular environment. PMID:24084333
Ari, Seyhmus; Nergiz, Yusuf; Aksit, Ihsan; Sahin, Alparslan; Cingu, Kursat; Caca, Ihsan
To evaluate the effects of intracameral injection of ranibizumab and bevacizumab on the corneal endothelium by scanning electron microscopy (SEM). Twenty-eight female rabbits were randomly divided into four equal groups. Rabbits in groups 1 and 2 underwent intracameral injection of 1 mg/0.1 mL and 0.5 mg/0.05 mL ranibizumab, respectively; group 3 was injected with 1.25 mg/0.05 mL bevacizumab. All three groups were injected with a balanced salt solution (BSS) into the anterior chamber of the left (fellow) eye. None of the rabbits in group 4 underwent an injection. Corneal thickness and intraocular pressure were measured before the injections, on the first day, and in the first month after injection. The rabbits were sacrificed and corneal tissues were excised in the first month after injection. Specular microscopy was used for the corneal endothelial cell count. Endothelial cell density was assessed and comparisons drawn between the groups and the control. Micrographs were recorded for SEM examination. The structure of the corneal endothelial cells, the junctional area of the cell membrane, the distribution of microvillus, and the cell morphology of the eyes that underwent intracameral injection of vascular endothelial growth factor (VEGF), BSS, and the control group were compared. Corneal thickness and intraocular pressure were not significantly different between the groups that underwent anti-VEGF or BSS injection and the control group on the first day and in the first month of injection. The corneal endothelial cell count was significantly diminished in all three groups; predominantly in group 1 and 2 (P<0.05). The SEM examination revealed normal corneal endothelial histology in group 3 and the control group. Eyes in group 1 exhibited indistinctness of corneal endothelial cell borders, microvillus loss in the luminal surface, excessive blebbing, and disintegration of intercellular junctions. In group 2, the cell structure of the corneal endothelium
Fukuda, Masamichi; Takeda, Nobuo; Shibata, Shinsuke; Shibata, Naoko; Shibata, Teppei; Sugiyama, Kazuhisa; Sasaki, Hiroshi
To examine the relevance of concentration of benzalkonium chloride (BAK) on the cornea, we investigated the effects of latanoprost containing BAK alone and in combination with other antiglaucoma drug classes on corneal epithelium in vitro in a cultured rabbit corneal cell line (SIRC) and in vivo, using a corneal resistance device (CRD). [In vitro] staten's seruminstitut rabbit corneal cells were exposed to 0.005% latanoprost for 30s, followed by either phosphate buffered saline (control), 0.1% brimonidine, 0.5% timolol, 1% dorzolamide, or 1% brinzolamide. The number of viable cells was counted at 8, 15, and 30min. [In vivo] Albino rabbits were administered one drop of 0.005% latanoprost, followed 5min later by one drop of an agent from the in vitro trial. This was repeated every 15min for a total of three times. The change in corneal barrier function was assessed by measuring the corneal resistance at 2 and 30min after the final administration. [In vitro] At 8min, the viable cell count in the latanoprost+dorzolamide group was significantly lower than in the control group. At 15 and 30min, all treatment groups, except the latanoprost+brimonidine group, demonstrated significantly lower viable cell counts than the control group. [In vivo] At 2min after the final eye drop, the latanoprost+timolol group and the latanoprost+brinzolamide group demonstrated significantly lower corneal resistance than did the latanoprost+brimonidine group. No significant difference was observed between the agents at 30min. In conclusion, when combining latanoprost containing benzalkonium chloride with other classes of antiglaucoma drugs, brimonidine may cause the least corneal damage, and the number of drug administrations may be an important factor.
Igarashi, Tsutomu; Ohsawa, Ikuroh; Kobayashi, Maika; Igarashi, Toru; Suzuki, Hisaharu; Iketani, Masumi; Takahashi, Hiroshi
In phacoemulsification, ultrasound induces hydroxyl radical (·OH) formation, damaging corneal endothelium. Whether H2 can prevent such oxidative damage in phacoemulsification was examined by in vitro and in vivo studies. H2 was dissolved in a commercial irrigating solution. The effects of H2 against ·OH generation were first confirmed in vitro by electron-spin resonance (ESR) and hydroxyphenyl fluorescein (HPF). ESR showed a significantly decreased signal magnitude, and fluorescence intensity by oxidized HPF was significantly less in the H2-dissolved solution. The effects of H2 in phacoemulsification were evaluated in rabbits, comparing H2-dissolved and control solutions. Five hours after the procedure, the whole cornea was excised and subjected to image analysis for corneal edema, real-time semiquantitative PCR (qPCR) for heme oxygenase (HO)-1, catalase (CAT), superoxide dismutase 1 (SOD1), and SOD2 mRNA, and immunohistochemistry. Corneal edema was significantly less and the increases in anti-oxidative HO-1, CAT and SOD2 mRNA expressions were significantly suppressed in the H2 group. In addition, corneal endothelial cell expressions of two oxidative stress markers, 4-HNE and 8-OHdG, were significantly lower in the H2 group. In conclusion, H2 dissolved in the ocular irrigating solution protected corneal endothelial cells from phacoemulsification-induced oxidative stress and damage. PMID:27498755
Du, Jun; Zheng, Guang-Ying; Wen, Cheng-Lin; Zhang, Xiao-Fang; Zhu, Yu
AIM To evaluate the clinical value of wedge resection at corneal limbus in patients with traumatic corneal scarring and high irregular astigmatism. METHODS Patients with traumatic corneal astigmatism received wedge resection at least 6mo after suture removal from corneal wound. The uncorrected distance visual acuities (UCVA) and best corrected distance visual acuities (BCVA), pre- and post-operation astigmatism, spherical equivalent (SE), safety and complications were evaluated. RESULTS Ten eyes (10 patients) were enrolled in this study. Mean follow-up time after wedge resection was 37.8±15.4mo (range, 20-61mo). The mean UCVA improved from +1.07±0.55 logMAR to +0.43±0.22 logMAR (P=0.000) and the mean BCVA from +0.50±0.30 logMAR to +0.15±0.17 logMAR (P=0.000). The mean astigmatism power measured by retinoscopy was -2.03±2.27 D postoperatively and -2.83±4.52 D preoperatively (P=0.310). The mean SE was -0.74±1.61 D postoperatively and -0.64±1.89 D preoperatively (P=0.601). Two cases developed mild pannus near the sutures. No corneal perforation, infectious keratitis or wound gape occurred. CONCLUSION Corneal-scleral limbal wedge resection with compression suture is a safe, effective treatment for poor patients with high irregular corneal astigmatism after corneal-scleral penetrating injury. Retinoscopy can prove particularly useful for high irregular corneal astigmatism when other measurements are not amenable. PMID:27366685
Lee, Hun; Park, Si Yoon; Yong Kang, David Sung; Ha, Byoung Jin; Choi, Jin Young; Kim, Eung Kweon; Seo, Kyoung Yul; Kim, Tae-Im
To evaluate the effects of photorefractive keratectomy (PRK) combined with corneal wavefront-guided ablation profiles and hyperaspheric ablation profiles on changes in higher-order aberrations (HOAs). Yonsei University College of Medicine and Eyereum Clinic, Seoul, South Korea. Comparative observational case series. Medical records of patients who had corneal wavefront-guided hyperaspheric PRK, corneal wavefront-guided mild-aspheric PRK, or non-corneal wavefront-guided mild-aspheric PRK were analyzed. The logMAR uncorrected distance visual acuity (UDVA), manifest refraction spherical equivalent (MRSE), and changes in corneal aberrations (root-mean-square [RMS] HOAs, spherical aberration, coma) were evaluated 1, 3, and 6 months postoperatively. The records of 61 patients (96 eyes) were reviewed. There was no statistically significant difference in logMAR UDVA or MRSE between the 3 groups at any timepoint. Corneal RMS HOAs were significantly smaller in the corneal wavefront-guided hyperaspheric group and the corneal wavefront-guided mild-aspheric group than in the noncorneal wavefront-guided mild-aspheric group at each timepoint. Corneal spherical aberration was significantly smaller for corneal wavefront-guided hyperaspheric PRK than for noncorneal wavefront-guided mild-aspheric PRK 6 months postoperatively. Changes in corneal spherical aberration (preoperatively and 6 months postoperatively) in corneal wavefront-guided hyperaspheric PRK were significantly smaller than in corneal wavefront-guided mild-aspheric PRK (P = .046). Corneal coma was significantly smaller with corneal wavefront-guided hyperaspheric PRK and corneal wavefront-guided mild-aspheric PRK than with noncorneal wavefront-guided mild-aspheric PRK 3 months and 6 months postoperatively. Corneal wavefront-guided hyperaspheric PRK induced less corneal spherical aberration 6 months postoperatively than corneal wavefront-guided mild-aspheric PRK and noncorneal wavefront-guided mild-aspheric PRK
Benezra, Miriam; Greenberg, Roseanne S; Masur, Sandra K
Within the multidomain structure of ZO-1 are motifs responsible for ZO-1's localization to intercellular junctions and its newly demonstrated localization to the leading edge of lamellipodia in corneal fibroblasts. Since ZO-1 also has two nuclear localization signals, this study was undertaken to determine whether stimuli associated with wounding would induce nuclear translocation of ZO-1 Immunocytochemistry and immunoblot analysis were used to localize endogenous and exogenous ZO-1 in nuclear and cytoplasmic sites in corneal fibroblasts and 293T fibroblasts, with and without myc-ZO-1 transfection. Cells were serum starved by growth for 48 hours in DMEM/F12 with 0.2% FBS and subsequently were either scrape wounded or treated with 10% FBS, PDGF, or FGF-2 for 6 hours. For immunoblot analysis, after lysis, the nuclear and cytosolic fractions were separated and analyzed by SDS-PAGE. Cells on companion coverslips were fixed with 3% p-formaldehyde and permeabilized with 1% Triton before immunocytochemical detection of ZO-1 and nuclear proteins. ZO-1 was rarely detected in the nucleus of serum-starved corneal fibroblasts. In contrast, it colocalized with nucleolin in the nucleoli of corneal fibroblasts after serum-starved cells were treated with 10% FBS, PDGF, or FGF-2. Immunoblot analysis confirmed the immunocytochemical results: Little ZO-1 was detected in the nuclear fraction of lysates of serum-starved cells, but ZO-1 was found in the nuclear fractions of rabbit corneal and 293T fibroblasts treated with 10% FBS, PDGF, or FGF-2. Furthermore in scrape-wounded corneal fibroblasts, ZO-1 was localized to nucleoli of both serum-starved and serum-treated cells. Localization of ZO-1 to nucleoli of corneal and 293T fibroblasts under proliferative and promigratory conditions suggests a physiologically significant interaction of ZO-1 with proteins in nucleoli during the healing process.
Strong, Travis D; Tangeman, Sarah; Ben-Shlomo, Gil; Haynes, Joseph; Allbaugh, Rachel A
To present the clinicopathologic features of a Domestic Short-haired cat with spontaneous, intermediate-grade corneal fibrosarcoma, possibly secondary to chronic corneal irritation associated with a corneal sequestrum. A 12-year-old, spayed female Domestic Short-haired cat was evaluated for a slowly growing, pink, exophytic mass affecting the left cornea. The cat had presented 6 years previously for bilateral brown corneal sequestra, as well as 3 years previously for a small pale growth on the left cornea hypothesized to be an epithelial inclusion cyst and a corneal ulcer affecting the right eye. Incisional biopsy of the corneal mass indicated intermediate-grade corneal fibrosarcoma within the corneal stroma. Owing to the potential for malignant behavior, the left globe was enucleated. Routine systemic staging was performed prior to surgery with no evidence of metastasis. Definitive diagnosis of corneal fibrosarcoma was made through histopathologic examination of the incisional biopsy. There was an elevated mitotic index, indicating an intermediate-grade phenotype. Histopathology of the enucleated globe substantiated the initial findings, and complete tumor resection was confirmed. Subjacent to the corneal fibrosarcoma, there was a region of necrotic tissue suggestive of a corneal sequestrum. Six months after diagnosis and enucleation, the patient remained healthy with no signs of local spread or distant metastasis. To the authors' knowledge, this is the first documented case of a corneal fibrosarcoma in a cat. © 2016 American College of Veterinary Ophthalmologists.
Pitz, S; Jahn, R; Frisch, L; Duis, A; Pfeiffer, N
Background: The performance and results of corneal tattooing are described in a case series of 11 patients suffering from a disfiguring corneal scar using a technique similar to conventional dermatography. Methods: Drawing ink in different shades was applied into the anterior corneal stroma by punctures performed with a conventional spatula needle. Results: Up to 4 years after surgery all patients still had satisfactory staining of the formerly cosmetically disfiguring corneal scar. Conclusion: Tattooing of unsightly corneal scars proved to be an efficient and easy to perform technique, yielding acceptable results during follow up. PMID:11914207
Robertson, Danielle M.; Rogers, Nathan A.; Petroll, W. Matthew; Zhu, Meifang
Pseudomonas aeruginosa is a pathogenic gram-negative organism that has the ability to cause blinding corneal infections following trauma and during contact lens wear. In this study, we investigated the directional movement and orientation of an invasive corneal isolate of P. aeruginosa in the corneal stroma during infection of ex vivo and in vivo rabbit corneas using multiphoton fluorescence and second harmonic generation (SHG) imaging. Ex vivo, rabbit corneas were subject to three partial thickness wounds prior to inoculation. In vivo, New Zealand white rabbits were fit with P. aeruginosa laden contact lenses in the absence of a penetrating wound. At all time points tested, infiltration of the corneal stroma by P. aeruginosa revealed a high degree of alignment between the bacteria and collagen lamellae ex vivo (p < 0.001). In vivo, P. aeruginosa traveled throughout the stroma in discrete regions or bands. Within each region, the bacteria showed good alignment with collagen lamellae (P = 0.002). Interestingly, in both the in vitro and in vivo models, P. aeruginosa did not appear to cross the corneal limbus. Taken together, our findings suggest that P. aeruginosa exploits the precise spacing of collagen lamellae in the central cornea to facilitate spread throughout the stroma. PMID:28397809
Okumura, Naoki; Okazaki, Yugo; Inoue, Ryota; Nakano, Shinichiro; Fullwood, Nigel J; Kinoshita, Shigeru; Koizumi, Noriko
Ripasudil (Glanatec), a selective Rho-associated coiled coil-containing protein kinase (ROCK) inhibitor, was approved in Japan in September 2014 for the treatment of glaucoma and ocular hypertension. The purpose of this study was to investigate the effect of ripasudil eye drops on corneal endothelial morphology, as ROCK signaling is known to modulate the actin cytoskeleton. Morphological changes in the corneal endothelium were evaluated in human subjects by specular and slit-lamp microscopy, following topical administration of ripasudil. We also used a rabbit model to evaluate the effect of ripasudil on clinical parameters of the corneal endothelium. Twenty-four hours after ripasudil application, corneal specimens were evaluated by phalloidin staining, immunohistochemical analysis, and electron microscopy. Specular microscopy revealed morphological changes in human eyes, and slit-lamp microscopy showed guttae-like findings. The rabbit model showed morphological changes similar to those seen in human eyes after ripasudil administration. Electron microscopy demonstrated that these alterations are due to the formation of protrusions along the cell-cell borders, but this formation is transient. Expression of corneal endothelial function-related markers was not disrupted; corneal thickness and corneal volume were not changed; and no cell death was observed following ripasudil administration. Ripasudil induces transient guttae-like findings in humans, most likely due to protrusion formation along intracellular borders caused by the reduction in actomyosin contractility of the corneal endothelial cells. No severe adverse effects were observed. Physicians should be aware that ROCK inhibitors can cause these guttae-like findings, to avoid misdiagnosing patients as having Fuchs endothelial corneal dystrophy. (www.umin.ac.jp/ctr number, UMIN000018340.).
Sung, Shijun; Bajwa, Neha; Deng, Sophie X.; Taylor, Zachary; Grundfest, Warren
Well-regulated corneal water content is critical for ocular health and function and can be adversely affected by a number of diseases and injuries. Current clinical practice limits detection of unhealthy corneal water content levels to central corneal thickness measurements performed by ultrasound or optical coherence tomography. Trends revealing increasing or decreasing corneal thickness are fair indicators of corneal water content by individual measurements are highly inaccurate due to the poorly understood relationship between corneal thickness and natural physiologic variation. Recently the utility of THz imaging to accuarately measure corneal water content has been explored on with rabbit models. Preliminary experiments revealed that contact with dielectric windows confounded imaging data and made it nearly impossible to deconvolve thickness variations due to contact from thickness variations due to water content variation. A follow up study with a new optical design allowed the acquisition of rabbit data and the results suggest that the observed, time varying contrast was due entirely to the water dynamics of the cornea. This paper presents the first ever in vivo images of human cornea. Five volunteers with healthy cornea were recruited and their eyes were imaged three times over the course of a few minutes with our novel imaging system. Noticeable changes in corneal reflectivity were observed and attributed to the drying of the tear film. The results suggest that clinically compatible, non-contact corneal imaging is feasible and indicate that signal acquired from non-contact imaging of the cornea is a complicated coupling of stromal water content and tear film.
Ehlers, Niels; Hjortdal, Jesper; Nielsen, Kim
Corneal transplantation was conceptualized at the end of the 18th century, but it took more than 100 years before human corneal grafting was introduced. The greatest step forward was the demonstration by Filatov that corneal tissue can be collected and used post mortem. The history of eye banking includes the development of preservation techniques. Storage in cold to minimize microbial growth and tissue disintegration was first choice but during the last 30 years this has been taken over by warm storage (organ culture) where the donor cornea proves its sterility and vitality before being transferred to the recipient. The long-term organ culture storage makes exchange between centres possible and allows for histocompatibility matching. The internationalization led to the establishing of the European Eye Bank Association but also to an increasing number of governmental regulations. Developments in years to come may lead to control of graft biomechanics and optics. This technical development tends to favour a centralization.
Filip, M; Cârstocea, B; Beşleagă, C
Corneal transplant become a surgical procedure which is performed with success in more many ophthalmological medico-surgical centers. This way it raised a fully experience concerning selection of cases and the preservation of the graft, surgical technique and the graft rejection. The authors present a general view of the problems concerning keratoplasty making a briefly summary of the indications, contraindications and prognosis of this technique, screening of donor tissue and a little larger one the surgical technique with his problems: trephining, preserving the donor tissue and placing the graft, and also the postoperative problems--suture removal, visual correction and corneal transplant rejection.
Although corneal abrasions are commonly seen in primary care settings, the primary care literature contains scant references on detecting and managing this problem. This article provides an overview of corneal abrasion assessment and treatment. Four common etiologies of abrasion are discussed: traumatic abrasion, contact lens abrasion, foreign body abrasion, and recurrent erosion. Parameters for the history and physical examination are outlined, including sections on contact lens removal, lid eversion, and fluorescein staining. Treatment regimens for each of the etiologies are discussed, with a focus on current research on using pressure eye patches as an intervention. Indications for referral to an ophthalmologist are noted.
Kim, Tae-im; Chung, Jae Lim; Hong, Jin Pyo; Min, Kyung; Seo, Kyoung Yul; Kim, Eung Kweon
Vascular endothelial growth factor (VEGF) is essential for neovascularization, but the use of anti-VEGF therapies to inhibit neovascularization may influence epithelial wound healing. Here, the effects of bevacizumab on corneal epithelial wound healing time in rabbit models, cell proliferation, and expression of integrins in human corneal epithelial and fibroblast cells were evaluated. To compare epithelial wound healing times, epithelial defect sizes were measured after application of bevacizumab topical eye drops at 0, 0.5, 1.0, 1.5, 2.5, or 5 mg/mL, twice daily, to mechanically debrided epithelia of rabbit corneas. The cellular covering of wounded areas and expression of Ki67 were assessed after scrape injuries in cultures of human corneal epithelial and fibroblast cells. Expression of cell surface integrins and collagens was measured using plates coated with mouse monoclonal antibodies against human adhesion molecules, and relevant mRNA levels were assessed by reverse-transcription-polymerase chain reaction (RT-PCR). The application of bevacizumab topical eye drops at 1.0, 1.5, 2.5, or 5 mg/mL delayed rabbit corneal epithelial healing. Cell cultures growing under high concentrations of bevacizumab showed delay in the proliferation of corneal epithelial and fibroblast cells. Surface expression of mRNA encoding integrins and collagens were decreased by 1.5 mg/mL of bevacizumab. Bevacizumab delayed corneal epithelial wound healing and inhibited integrin expression. When bevacizumab is used to reduce the development of new corneal vessels, slight delays in epithelial wound healing are possible and cellular proliferation is to be expected.
Lindstrom, R L
The functional status of the endothelium and sustained corneal deturgescence after corneal preservation are of great clinical importance and have been primary goals in the development of corneal storage media. In our investigational studies we have specifically addressed the improvement of the quality of donor tissue after 4 degrees C storage, the extension of corneal preservation time, the enhancement of corneal wound healing, and the reduction of the normal progressive loss of endothelial cells postkeratoplasty. Specifically we have developed in vitro HCE cell and epithelial cell culture models that can accurately reflect the response of human corneal tissue in vivo. These models have been utilized to study the effects of growth factors and medium components in relation to their biocompatibility and efficacy in the development of improved corneal preservation solutions. Our laboratory investigated in vitro conditions that allowed human corneal endothelium to shift from a nonproliferative state, in which they remain viable and metabolically active, to a proliferative, mitotically active state. Isolation techniques developed in our laboratory have enabled the establishment of primary and subsequent subcultures of human corneal endothelium that retain the attributes of native endothelium. These in vitro conditions maintain HCE cells in a proliferative state, actively undergoing mitosis. A quantitative bioassay has been developed to determine the effects of various test medium in the stimulation or inhibition of DNA synthesis. In attempting to learn more about the events that occur during in vitro endothelial cell isolation, cell reattachment, extracellular matrix interaction and migrating during subculture, SEM was done on isolated HCE cells incubated in CSM. These studies suggest that the components of the extracellular matrix modulate the growth response of HCE cells, and play a role in regulating proliferation and migration. These observations are important in
Ghoghawala, Shahed Y; Mannis, Mark J; Pullar, Christine E; Rosenblatt, Mark I; Isseroff, R Rivkah
Beta-adrenergic receptor (AR) antagonists are frequently prescribed ophthalmic drugs, yet previous investigations into how catecholamines affect corneal wound healing have yielded conflicting With the use of an integrated pharmacologic and genetic approach, the authors investigated how the beta-AR impacts corneal epithelial healing. Migratory rates of cultured adult murine corneal epithelial (AMCE) cells and in vivo corneal wound healing were examined in beta2-AR(+/+) and beta2-AR(-/-) mice. Signaling pathways were evaluated by immunoblotting. results. The beta-AR agonist isoproterenol decreased AMCE cell migratory speed to 70% of untreated controls, and this was correlated with a 0.60-fold decrease in levels of activated phospho-ERK (P-ERK). Treatment with the beta-AR antagonist (timolol) increased speed 33% and increased P-ERK 2.4-fold (P < 0.05). The same treatment protocols had no effect on AMCE cells derived from beta2-AR(-/-) mice; all treatment groups showed statistically equivalent migratory speeds and ERK phosphorylation. In beta2-AR(+/+) animals, the beta-AR agonist (isoproterenol) delayed the rate of in vivo corneal wound healing by 79%, whereas beta-AR antagonist (timolol) treatment increased the rate of healing by 16% (P < 0.05) compared with saline-treated controls. In contrast, in the beta2-AR(-/-) mice, all treatment groups demonstrated equivalent rates of wound healing. Additionally, murine corneal epithelial cell expressed the catecholamine-synthesizing enzyme tyrosine hydroxylase and detectable levels of epinephrine (184.5 pg/mg protein). The authors provide evidence of an endogenous autocrine catecholamine signaling pathway dependent on an intact beta2-AR for the modulation of corneal epithelial wound repair.
Zheng, Luo Luo; Vanchinathan, Vijay; Dalal, Roopa; Noolandi, Jaan; Waters, Dale J; Hartmann, Laura; Cochran, Jennifer R; Frank, Curtis W; Yu, Charles Q; Ta, Christopher N
We evaluated the biocompatibility of a poly(ethylene glycol) and poly(acrylic acid) (PEG/PAA) interpenetrating network hydrogel designed for artificial cornea in a rabbit model. PEG/PAA hydrogel measuring 6 mm in diameter was implanted in the corneal stroma of twelve rabbits. Stromal flaps were created with a microkeratome. Randomly, six rabbits were assigned to bear the implant for 2 months, two rabbits for 6 months, two rabbits for 9 months, one rabbit for 12 months, and one rabbit for 16 months. Rabbits were evaluated monthly. After the assigned period, eyes were enucleated, and corneas were processed for histology and immunohistochemistry. There were clear corneas in three of six rabbits that had implantation of hydrogel for 2 months. In the six rabbits with implant for 6 months or longer, the corneas remained clear in four. There was a high rate of epithelial defect and corneal thinning in these six rabbits. One planned 9-month rabbit developed extrusion of implant at 4 months. The cornea remained clear in the 16-month rabbit but histology revealed epithelial in-growth. Intrastromal implantation of PEG/PAA resulted in a high rate of long-term complications.
Zheng, Luo Luo; Vanchinathan, Vijay; Dalal, Roopa; Noolandi, Jaan; Waters, Dale J.; Hartmann, Laura; Cochran, Jennifer R.; Frank, Curtis W.; Yu, Charles Q.; Ta, Christopher N.
We evaluated the biocompatibility of a poly(ethylene glycol) and poly(acrylic acid) (PEG/PAA) interpenetrating network hydrogel designed for artificial cornea in a rabbit model. PEG/PAA hydrogel measuring 6 mm in diameter was implanted in the corneal stroma of twelve rabbits. Stromal flaps were created with a microkeratome. Randomly, six rabbits were assigned to bear the implant for 2 months, two rabbits for 6 months, two rabbits for 9 months, one rabbit for 12 months, and one rabbit for 16 months. Rabbits were evaluated monthly. After the assigned period, eyes were enucleated, and corneas were processed for histology and immunohistochemistry. There were clear corneas in three of six rabbits that had implantation of hydrogel for 2 months. In the six rabbits with implant for 6 months or longer, the corneas remained clear in four. There was a high rate of epithelial defect and corneal thinning in these six rabbits. One planned 9-month rabbit developed extrusion of implant at 4 months. The cornea remained clear in the 16-month rabbit but histology revealed epithelial in-growth. Intrastromal implantation of PEG/PAA resulted in a high rate of long-term complications. PMID:25778285
Schultz, R O; Peters, M A; Sobocinski, K; Nassif, K; Schultz, K J
Corneal epithelial lesions can be found in approximately one-half of asymptomatic patients with diabetes mellitus. These lesions are transient and clinically resemble the keratopathy seen in staphylococcal keratoconjunctivitis. Staphylococcal organisms, however, can be isolated in equal percentages from diabetic patients without keratopathy. Diabetic peripheral neuropathy was found to be related to the presence of diabetic keratopathy after adjusting for age with analysis of covariance. The strongest predictor of both keratopathy and corneal fluorescein staining was vibration perception threshold in the toes (P less than 0.01); and the severity of keratopathy was directly related to the degree of diminution of peripheral sensation. Other predictors of keratopathy were: reduced tear breakup time (P less than 0.03), type of diabetes (P less than 0.01), and metabolic status as indicated by c-peptide fasting (P less than 0.01). No significant relationships were found between the presence of keratopathy and tear glucose levels, endothelial cell densities, corneal thickness measurements, the presence of S epidermidis, or with duration of disease. It is our conclusion that asymptomatic epithelial lesions in the nontraumatized diabetic cornea can occur as a manifestation of generalized polyneuropathy and probably represent a specific form of corneal neuropathy. Images FIGURE 1 FIGURE 2 FIGURE 3 PMID:6676964
Batawi, Hatim; Kothari, Nikisha; Camp, Andrew; Bernhard, Luis; Karp, Carol L.; Galor, Anat
Purpose We report the case of a 77-year-old man with no history of keratoconus or other ectatic disorders who presented with corneal hydrops in the setting of a corneal ulcer. The risk factors, pathogenesis and treatment options of corneal hydrops are discussed. Method This is an observational case report study. Results A 77-year-old man presented with a 1-day history of severe pain, redness, mucous discharge and photophobia in the right eye. A slit-lamp examination of the right eye showed an area of focal corneal edema and protrusion. Within the area of edema and protrusion, there was an infiltrate with an overlying epithelial defect consistent with an infectious corneal ulcer. The Seidel test showed no leakage, so a clinical diagnosis of corneal hydrops associated with nonperforated corneal ulcer was made. With appropriate antibiotic treatment, the corneal ulcer and hydrops both resolved over a 1-month period. Conclusion Corneal hydrops can occur in the setting of corneal infections. PMID:26889160
Marcos, Susana; Kling, Sabine; Bekesi, Nandor; Dorronsoro, Carlos
The combination of air-puff systems with real-time corneal imaging (i.e. Optical Coherence Tomography (OCT), or Scheimpflug) is a promising approach to assess the dynamic biomechanical properties of the corneal tissue in vivo. In this study we present an experimental system which, together with finite element modeling, allows measurements of corneal biomechanical properties from corneal deformation imaging, both ex vivo and in vivo. A spectral OCT instrument combined with an air puff from a non-contact tonometer in a non-collinear configuration was used to image the corneal deformation over full corneal cross-sections, as well as to obtain high speed measurements of the temporal deformation of the corneal apex. Quantitative analysis allows direct extraction of several deformation parameters, such as apex indentation across time, maximal indentation depth, temporal symmetry and peak distance at maximal deformation. The potential of the technique is demonstrated and compared to air-puff imaging with Scheimpflug. Measurements ex vivo were performed on 14 freshly enucleated porcine eyes and five human donor eyes. Measurements in vivo were performed on nine human eyes. Corneal deformation was studied as a function of Intraocular Pressure (IOP, 15-45 mmHg), dehydration, changes in corneal rigidity (produced by UV corneal cross-linking, CXL), and different boundary conditions (sclera, ocular muscles). Geometrical deformation parameters were used as input for inverse finite element simulation to retrieve the corneal dynamic elastic and viscoelastic parameters. Temporal and spatial deformation profiles were very sensitive to the IOP. CXL produced a significant reduction of the cornea indentation (1.41x), and a change in the temporal symmetry of the corneal deformation profile (1.65x), indicating a change in the viscoelastic properties with treatment. Combining air-puff with dynamic imaging and finite element modeling allows characterizing the corneal biomechanics in-vivo.
Parra, Felix I.; Catto, Peter J.
We compare two different derivations of the gyrokinetic equation: the Hamiltonian approach in Dubin D H E et al (1983 Phys. Fluids 26 3524) and the recursive methodology in Parra F I and Catto P J (2008 Plasma Phys. Control. Fusion 50 065014). We prove that both approaches yield the same result at least to second order in a Larmor radius over macroscopic length expansion. There are subtle differences in the definitions of some of the functions that need to be taken into account to prove the equivalence.
Petroll, W Matthew; Weaver, Matthew; Vaidya, Saurabh; McCulley, James P; Cavanagh, H Dwight
The purpose of this study was to develop and test hardware and software modifications to allow quantitative full-thickness corneal imaging using the Heidelberg Retina Tomograph (HRT) Rostock Corneal Module. A personal computer-controlled motor drive with positional feedback was integrated into the system to allow automated focusing through the entire cornea. The left eyes of 10 New Zealand white rabbits were scanned from endothelium to epithelium. Image sequences were read into a custom-developed program for depth calculation and measurement of sublayer thicknesses. Three-dimensional visualizations were also generated using Imaris. In 6 rabbits, stack images were registered, and depth-dependent counts of keratocyte nuclei were made using Metamorph. The mean epithelial and corneal thickness measured in the rabbit were 47 ± 5 μm and 373 ± 25 μm, respectively (n = 10 corneas); coefficients of variation for repeated scans were 8.2% and 2.1%. Corneal thickness measured using ultrasonic pachymetry was 374 + 17 μm. The mean overall keratocyte density measured in the rabbit was 43,246 ± 5603 cells per cubic millimeter in vivo (n = 6 corneas). There was a gradual decrease in keratocyte density from the anterior to posterior cornea (R = 0.99), consistent with previous data generated in vitro. This modified system allows high-resolution 3-dimensional image stacks to be collected from the full-thickness rabbit cornea in vivo. These data sets can be used for interactive visualization of corneal cell layers, measurement of sublayer thickness, and depth-dependent keratocyte density measurements. Overall, the modifications significantly expand the potential quantitative research applications of the HRT Rostock Cornea Module microscope.
Leonard, Elissa K; Pai, Vincent H; Amberg, Philip; Gardner, Jens; Orwin, Elizabeth J
Mechanical strain is an important signal that influences the behavior and properties of cells in a wide variety of tissues. Physiologically similar mechanical strain can revert cultured cells to a more normal phenotype. Here, we have demonstrated that 3% equibiaxial (EB) and uniaxial strains confer favorable protein expression in cultured rabbit corneal fibroblasts (RCFs), with approximately 35% and 65% reduction in expression of α-smooth muscle actin (α-SMA), respectively. We have designed a novel bioreactor that is capable of imparting up to 7% EB strain and up to 6% EB strain using a cornea-shaped post. Additional features of the bioreactor include the application of shear stress to cells in culture and the ability to image cells using optical coherence microscopy (OCM) without being removed from the system. Copyright © 2012 Wiley Periodicals, Inc.
Amrite, Aniruddha C.; Edelhauser, Henry F.; Kompella, Uday B.
Purpose To develop pharmacokinetics models to describe the disposition of small lipophilic molecules in the cornea and retina after periocular (subconjunctival or posterior subconjunctival) administration. Methods Compartmental pharmacokinetics analysis was performed on the corneal and retinal data obtained after periocular administration of 3 mg of celecoxib (a selective COX-2 inhibitor) to Brown Norway (BN) rats. Berkeley Madonna, a differential and difference equation–based modeling software, was used for the pharmacokinetics modeling. The data were fit to different compartment models with first-order input and disposition, and the best fit was selected on the basis of coefficient of regression and Akaike information criteria (AIC). The models were validated by using the celecoxib data from a prior study in Sprague-Dawley (SD) rats. The corneal model was also fit to the corneal data for prednisolone at a dose of 2.61 mg in albino rabbits, and the model was validated at two other doses of prednisolone (0.261 and 26.1 mg) in these rabbits. Model simulations were performed with the finalized model to understand the effect of formulation on corneal and retinal pharmacokinetics after periocular administration. Results Celecoxib kinetics in the BN rat cornea can be described by a two-compartment (periocular space and cornea, with a dissolution step for periocular formulation) model, with parallel elimination from the cornea and the periocular space. The inclusion of a distribution compartment or a dissolution step for celecoxib suspension did not lead to an overall improvement in the corneal data fit compared with the two-compartment model. The more important parameter for enhanced fit and explaining the apparent lack of an increase phase in the corneal levels is the inclusion of the initial leak-back of the dose from the periocular space into the precorneal area. The predicted celecoxib concentrations from this model also showed very good correlation (r = 0
Ma, Hongxia; Zheng, Lin; Liu, Yunbo; Zhao, Chenyan; Harrison, Tim J.; Ma, Yuyuan; Sun, Shuhua; Zhang, Jingang; Wang, Youchun
Background A recent study provided evidence that farmed rabbits in China harbor a novel hepatitis E virus (HEV) genotype. Although the rabbit HEV isolate had 77–79% nucleotide identity to the mammalian HEV genotypes 1 to 4, their genomic organization is very similar. Since rabbits are used widely experimentally, including as models of infection, we investigated whether they constitute an appropriate animal model for human HEV infection. Methods Forty-two SPF rabbits were divided randomly into eleven groups and inoculated with six different isolates of rabbit HEV, two different doses of a second-passage rabbit HEV, and with genotype 1 and 4 HEV. Sera and feces were collected weekly after inoculation. HEV antigen, RNA, antibody and alanine aminotransferase in sera and HEV RNA in feces were detected. The liver samples were collected during necropsy subject to histopathological examination. Findings Rabbits inoculated with rabbit HEV became infected with HEV, with viremia, fecal virus shedding and high serum levels of viral antigens, and developed hepatitis, with elevation of the liver enzyme, ALT. The severity of disease corresponded to the infectious dose (genome equivalents), with the most severe hepatic disease caused by strain GDC54-18. However, only two of nine rabbits infected with HEV genotype 4, and none infected with genotype 1, developed hepatitis although six of nine rabbits inoculated with the genotype 1 HEV and in all rabbits inoculated with the genotype 4 HEV seroconverted to be positive for anti-HEV IgG antibody by 14 weeks post-inoculation. Conclusions These data indicate that rabbits are an appropriate model for rabbit HEV infection but are not likely to be useful for the study of human HEV. The rabbit HEV infection of rabbits may provide an appropriate parallel animal model to study HEV pathogenesis. PMID:20161794
Yu, Ji-guo; Bao, Fang-jun; Feng, Yi-fan; Whitford, Charles; Ye, Ting; Huang, Yan-bing; Wang, Qin-mei; Elsheikh, Ahmed
To determine the biomechanical response of the rabbit cornea to inflation under posterior and anterior pressure. Twelve Japanese white rabbits were included in the study. A randomly selected eye from each animal was subjected to posterior pressure in an inflation test rig, and the other eye was subjected to anterior pressure after manually reversing its curvature. Specimens were loaded by cycles of pressure up to 40 mmHg, and the experimentally obtained pressure-deformation data were used to derive the stress-strain behavior of each eye using an inverse modeling procedure. The differences between the two groups in corneal thickness, diameter, and intraocular pressure (IOP) were not statistically significant (P=.935, .879 and .368, respectively). Corneas tested under posterior pressure displayed significantly higher stiffness (as measured by the tangent modulus) than those inflated by anterior pressure (P<.001). Cornea is a nonlinear viscoelastic tissue that presents different mechanical properties when tested under posterior and anterior pressure. The determination of the behavior under both forms of pressure could contribute to the construction of accurate finite element simulations of corneal behavior and the correction of tonometric IOP measurements. The difference in mechanical behavior between anteriorly and posteriorly loaded corneas in the study, although significant, could have been partly affected by the changes in microstructure possibly caused by changing corneal form to enable anterior loading. Copyright 2013, SLACK Incorporated.
Wang, Shang; Larin, Kirill V.
Noninvasive high-resolution depth-resolved measurement of corneal biomechanics is of great clinical significance for improving the diagnosis and optimizing the treatment of various degenerated ocular diseases. Here, we report a micro-scale optical coherence elastography (OCE) method that enables noncontact assessment of the depthwise elasticity distribution in the cornea. The OCE system combines a focused air-puff device with phase-sensitive optical coherence tomography (OCT). Low-pressure short-duration air stream is used to load the cornea with the localized displacement at micron level. The phase-resolved OCT detection with nano-scale sensitivity probes the induced corneal deformation at various locations within a scanning line, providing the ultra-fast imaging of the corneal lamb wave propagation. With spectral analysis, the amplitude spectra and the phase spectra are available for the estimation of the frequency range of the lamb wave and the quantification of the wave propagation, respectively. Curved propagation paths following the top and bottom corneal boundaries are selected inside the cornea for measuring the phase velocity of the lamb wave at the major frequency components over the whole depths. Our pilot experiments on ex vivo rabbit eyes indicate the distinct stiffness of different layers in the cornea, including the epithelium, the anterior stroma, the posterior stroma, and the innermost region, which demonstrates the feasibility of this micro-scale OCE method for noncontact depth-resolved corneal elastography. Also, the quantification of the lamb wave dispersion in the cornea could lead to the measurement of the elastic modulus, suggesting the potential of this method for quantitative monitoring of the corneal biomechanics.
Egorov, E A; Kalinin, N I; Kiiasov, A P
The efficacy of corneregel, a drug containing pantothenic acid, a component of coenzyme A, in healing of corneal wounds has been evaluated. The study was carried out on 19 rabbits (38 eyes) with standard corneal defect made with a 5-mm trephine for lamellar transplantation of the cornea, divided into 2 groups: 1) instillations of corneregel (10 eyes) and 0.25% levomycetin solution (10 eyes) and 2) 20% solcoseryl gel (9 eyes) and 0.25% levomycetin (9 eyes). Time course of changes were evaluated by biomicroscopy (fluorescent test), histologically (hematoxylin-eosin staining), and immunohistochemically after 1, 2, 4, 7, 30, and 90 days. Proliferative activity was studied by expression of the proliferating cell nuclear antigen and the migration capacity of cells by expression of alpha-smooth muscle actin. The terms of epithelialization were as follows: corneregel 10 +/- 7 h, 20% solcoseryl gel 108 +/- 10 h, levomycetin 124 +/- 6.93 h. Earlier epithelialization in the corneregel group was apparently due to increased expression of alpha-smooth muscle actin and increase in the cell migration capacity. Hence, corneregel is recommended for practical use as a stimulant of reparative regeneration of the cornea.
Schmitz, K; Lang, G K; Behrens-Baumann, W
The postoperative clinical course after penetrating keratoplasty and trephination in free form using a guided excimer laser beam has been published before. Here the findings of light-microscopy comparing corneal wound healing after experimental penetrating keratoplasty after laser trephination and after conventional mechanical trephination are presented. Homologous penetrating keratoplasty was performed on 12 NZW rabbits (6 animals with mechanical trephination, 6 animals with excimer laser trephination). The cutting edges achieved by both trephination techniques were examined by light microscopy in the remaining donor rings. During the postoperative follow-up animals were sacrificed at 3 and 6 weeks and at 3 months. Corneal specimens were retrieved and corneal healing processes were evaluated by light microscopy. The cutting edges of corneal excisions with the excimer laser demonstrated a high precision with only minimal collateral damage to adjacent tissue structures. At the different intervals both trephination groups demonstrated comparable stages of corneal wound healing regarding epithelial regeneration, stromal fibroblast migration with collagen synthesis and Descemet repair by endothelial synthesis of basement membrane. After 6 months corneal specimens of both groups demonstrated complete healing with nearly parallel orientation of newly synthesised collagen lamellae. Corneal thickness in the wound areas did not differ significantly from normal corneal tissue. Experimental follow-up studies to evaluate the feasibility of the developed technology of laser trephination in the living eye have shown no differences between conventional mechanical and excimer laser trephination with a guided beam. The present histology study also does not demonstrate any significant differences in corneal wound healing between the two trephination groups. Although excimer laser trephination along metal masks has now been established for several years, the here presented technique
Okumura, Naoki; Okazaki, Yugo; Inoue, Ryota; Kakutani, Kazuya; Nakano, Shinichiro; Kinoshita, Shigeru; Koizumi, Noriko
Ripasudil (Glanatec), a selective rho-associated coiled coil-containing protein kinase (ROCK) inhibitor, was approved as a glaucoma and ocular hypertension treatment in Japan in 2014. The purpose of this study was to investigate the feasibility of using ripasudil eye drops to treat corneal endothelial injuries. Cultured human corneal endothelial cells (HCECs) were treated with ripasudil, and 5-bromo-2'-deoxyuridine (BrdU) incorporation was evaluated by ELISA. A rabbit corneal endothelial damage model was also created by mechanically scraping the corneal endothelium, followed by topical ripasudil eye drop application for 2 weeks. The anterior segment was evaluated by slit-lamp microscopy, and central corneal thickness was measured by ultrasound pachymetry. Corneal specimens were evaluated by phalloidin staining and immunohistochemical analysis using antibodies against Ki67, N-cadherin, and Na+/K+-ATPase. Many more BrdU-positive cells were observed among the HCECs treated with ripasudil (0.3-30 μM) than among the control HCECs. Ripasudil-treated eyes in a rabbit model showed 91.5 ± 2.0% Ki67-positive cells after 48 hours, whereas control eyes showed 52.6 ± 1.3%. Five of six corneas became transparent in ripasudil-treated eyes, whereas zero of six corneas became transparent in the control eyes. Regenerated cell densities were higher in the eyes treated with ripasudil than in eyes treated with vehicle. Eyes treated with ripasudil expressed N-cadherin and Na+/K+-ATPase in almost all CECs, whereas this expression was decreased in control eyes. Ripasudil promoted corneal endothelial wound healing, supporting its development as eye drops for treating acute corneal endothelial damage due to eye surgeries, especially cataract surgery.
Wand, Kerstin; Neuhann, Raphael; Ullmann, Andrea; Plank, Katharina; Baumann, Michael; Ritter, Roland; Griffith, May; Lohmann, Chris P; Kobuch, Karin
To evaluate riboflavin-UV-A crosslinking as an alternative suture-free fixation method for biosynthetic corneal collagen implants. A range of cell-free corneal implants consisting of recombinant human collagen type III were examined. In vitro, the implants were crosslinked with different riboflavin solutions and irradiations. Ex vivo, the biosynthetic corneal implants were placed on the anterior cornea of porcine and rabbit eyes after performing deep anterior lamellar keratoplasty with a trephine, femtosecond laser, or excimer laser. UV-A crosslinking was performed with isotonic or hypotonic riboflavin at either standard or rapid procedure. The corneas were excised, fixed in PFA 4%, and embedded in paraffin. Crosslinking effects on the implants and the adhesion between implant and corneal bed were evaluated by slit-lamp biomicroscopy, optical coherence tomography (OCT) images, and histologically. After the crosslinking procedure, the implants showed different degrees of thinning. The accuracy of cutting the corneal bed was highest with the excimer laser. Good adhesion of the implant in the corneal bed could be demonstrated in OCT images. This was more accurate in porcine eyes than in rabbit eyes. Histologically, crosslinks between implant and corneal stroma were demonstrated. There was no difference between standard and rapid crosslinking procedures. Riboflavin-UV-A crosslinking as a fixation method for biosynthetic corneal collagen implants was demonstrated to be promising. It can reduce suture-related complications such as haze formation and surface irregularity. Stability of the implants, especially shrinkage after riboflavin-UV-A crosslinking, needs to be further evaluated. Biostability, integration, and long-term outcome are further evaluated in in vivo animal experiments.
Wacker, Katrin; McLaren, Jay W.; Kane, Katrina M.; Baratz, Keith H.; Patel, Sanjay V.
Purpose To assess corneal hydration control across a range of severity of Fuchs' endothelial corneal dystrophy (FECD) by measuring the percent recovery per hour (PRPH) of central corneal thickness after swelling the cornea and to determine its association with corneal morphologic parameters. Methods Twenty-three corneas of 23 phakic FECD patients and 8 corneas of 8 healthy control participants devoid of guttae were graded (modified Krachmer scale). Effective endothelial cell density (ECDe) was determined from the area of guttae and local cell density in confocal microscopy images. Steady-state corneal thickness (CTss) and standardized central corneal backscatter were derived from Scheimpflug images. Corneal swelling was induced by wearing a low-oxygen transmissible contact lens for 2 hours in the morning. De-swelling was measured over 5 hours after lens removal or until corneal thickness returned to CTss. Percent recovery per hour was 100 × (1 – e−k), where k was determined from CT(t) = (de−kt) + CTss, and where d was the initial change from CTss. Results After contact lens wear, corneas swelled by 9% (95% CI 9–10). Percent recovery per hour was 49%/h (95% CI 41–57) in controls and 37%/h in advanced FECD (95% CI 29–43, P = 0.028). Low PRPH was associated with disease severity, low ECDe, and increased anterior and posterior corneal backscatter. Anterior backscatter was associated with PRPH in a multivariable model (R2 = 0.44). Conclusions Corneal hydration control is impaired in advanced FECD and is inversely related to anterior corneal backscatter. Anterior corneal backscatter might serve as an indicator of impaired endothelium in FECD. PMID:27661858
Okumura, Naoki; Koizumi, Noriko; Ueno, Morio; Sakamoto, Yuji; Takahashi, Hiroaki; Tsuchiya, Hideaki; Hamuro, Junji; Kinoshita, Shigeru
Corneal endothelial dysfunction accompanied by visual disturbance is a primary indication for corneal transplantation. We previously reported that the adhesion of corneal endothelial cells (CECs) to a substrate was enhanced by the selective ROCK inhibitor Y-27632. It is hypothesized that the inhibition of ROCK signaling may manipulate cell adhesion properties, thus enabling the transplantation of cultivated CECs as a form of regenerative medicine. In the present study, using a rabbit corneal endothelial dysfunction model, the transplantation of CECs in combination with Y-27632 successfully achieved the recovery of corneal transparency. Complications related to cell injection therapy, such as the abnormal deposition of the injected cells as well as the elevation of intraocular pressure, were not observed. Reconstructed corneal endothelium with Y-27632 exhibited a monolayer hexagonal cell shape with a normal expression of function-related markers, such as ZO-1, and Na(+)/K(+)-ATPase, whereas reconstruction without Y-27632 exhibited a stratified fibroblastic phenotype without the expression of markers. Moreover, transplantation of CECs in primates in the presence of the ROCK inhibitor also achieved the recovery of long-term corneal transparency with a monolayer hexagonal cell phenotype at a high cell density. Taken together, these results suggest that the selective ROCK inhibitor Y-27632 enables cultivated CEC-based therapy and that the modulation of Rho-ROCK signaling activity serves to enhance cell engraftment for cell-based regenerative medicine. Copyright © 2012 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.
Yuan, Jin; Zhai, Jia-jie; Huang, Xi; Zhou, Shi-you
Abstract Purpose The aim of this study was to investigate the sensitization, pharmacokinetics, and absorption of FK506 after corneal transplantation. Methods New Zealand albino rabbits were divided into normal and corneal transplantation groups. Each group was divided into 5 subgroups—saline, blank matrix, high-dose, medium-dose, and low-dose, respectively. There were 10 rabbits in each subgroup. One drop (25 μL) of FK506 was administered topically to both eyes of the rabbits 4 times daily for 30 days. Thirty days later, 5 rabbits of each subgroup were sacrificed after the administration of the last dose. Both eyes were enucleated; the left eye was used for pathologic examination and the right eye for the determination of FK506 distribution. The other 5 rabbits in each subgroup were sacrificed 14 days after the former 5 rabbits were sacrificed, and their eyes were enucleated for pathologic examination and tissue distribution determination as the former 5 rabbits in each subgroup (the second batch). Results Fluorescein staining and local ocular reaction provided evidence that there were no significant differences between control and FK506-instilled eyes in the rabbit model at any of the tested doses. Histologic examination revealed no ocular abnormality in the rabbits instilled with any doses of FK506 eyedrop. The peak serum concentration (Cmax) of systemic absorption ranged from 4.31±0.79 ng/mL to 14.89±6.85 ng/mL. Conclusion Our study suggests that up to 0.1% FK506 administered 4 times a day (q.i.d.) topically is safe for the rabbit eye. However, further safety studies are required in view of systemic adverse effects. PMID:22136074
Yuan, Jin; Zhai, Jia-jie; Huang, Xi; Zhou, Shi-you; Chen, Jia-qi
The aim of this study was to investigate the sensitization, pharmacokinetics, and absorption of FK506 after corneal transplantation. New Zealand albino rabbits were divided into normal and corneal transplantation groups. Each group was divided into 5 subgroups--saline, blank matrix, high-dose, medium-dose, and low-dose, respectively. There were 10 rabbits in each subgroup. One drop (25 μL) of FK506 was administered topically to both eyes of the rabbits 4 times daily for 30 days. Thirty days later, 5 rabbits of each subgroup were sacrificed after the administration of the last dose. Both eyes were enucleated; the left eye was used for pathologic examination and the right eye for the determination of FK506 distribution. The other 5 rabbits in each subgroup were sacrificed 14 days after the former 5 rabbits were sacrificed, and their eyes were enucleated for pathologic examination and tissue distribution determination as the former 5 rabbits in each subgroup (the second batch). Fluorescein staining and local ocular reaction provided evidence that there were no significant differences between control and FK506-instilled eyes in the rabbit model at any of the tested doses. Histologic examination revealed no ocular abnormality in the rabbits instilled with any doses of FK506 eyedrop. The peak serum concentration (C(max)) of systemic absorption ranged from 4.31±0.79 ng/mL to 14.89±6.85 ng/mL. Our study suggests that up to 0.1% FK506 administered 4 times a day (q.i.d.) topically is safe for the rabbit eye. However, further safety studies are required in view of systemic adverse effects.
We evaluated the refractive consequences of corneal transplants using a biomechanical model with homogeneous and inhomogeneous Young's modulus distributions within the cornea, taking into account ablation of some stromal tissue. A FEM model was used to simulate corneal transplants in diseased cornea. The diseased cornea was modeled as an axisymmetric structure taking into account a nonlinearly elastic, isotropic formulation. The model simulating the penetrating keratoplasty procedure gives more change in the postoperative corneal curvature when compared to the models simulating the anterior and posterior lamellar graft procedures. When a lenticle shaped tissue was ablated in the graft during the anterior and posterior keratoplasty, the models provided an additional correction of about -3.85 and -4.45 diopters, respectively. Despite the controversy around the corneal thinning disorders treatment with volume removal procedures, results indicate that significant changes in corneal refractive power could be introduced by a corneal transplantation combined with myopic laser ablation.
Chaurasia, Shyam S.; Lim, Rayne R.; Lakshminarayanan, Rajamani; Mohan, Rajiv R.
Corneal diseases are the third leading cause of blindness globally. Topical nonsteroidal anti-inflammatory drugs (NSAIDs), steroids, antibiotics and tissue transplantation are currently used to treat corneal pathological conditions. However, barrier properties of the ocular surface necessitate high concentration of the drugs applied in the eye repeatedly. This often results in poor efficacy and several side-effects. Nanoparticle-based molecular medicine seeks to overcome these limitations by enhancing the permeability and pharmacological properties of the drugs. The promise of nanomedicine approaches for treating corneal defects and restoring vision without side effects in preclinical animal studies has been demonstrated. Numerous polymeric, metallic and hybrid nanoparticles capable of transporting genes into desired corneal cells to intercept pathologic pathways and processes leading to blindness have been identified. This review provides an overview of corneal diseases, nanovector properties and their applications in drug-delivery and corneal disease management. PMID:25941990
Zernii, E Yu; Gancharova, O S; Ishutina, I E; Baksheeva, V E; Golovastova, M O; Kabanova, E I; Savchenko, M S; Serebryakova, M V; Sotnikova, L F; Zamyatnin, A A; Philippov, P P; Senin, I I
Perioperative corneal abrasion is an ophthalmic complication commonly found in patients underwent general anesthesia. In this study, correlations between development of corneal injury and proteomic changes in tear film during general anesthesia were examined using an animal (rabbit) model. Being started after 1-h anesthesia, the process of accumulation of pathological changes in the cornea unequivocally led clinically significant abrasions following 3-6 h of the narcosis. The corneal damage was associated with alterations in profiles of major proteins of the tear film. Analysis of the tear proteome pointed to depression of lachrymal glands function, and suggested serotransferrin, serum albumin and annexin A1 as potential tear markers of the complication. The tear film alterations included fast drop of total antioxidant activity and activity of superoxide dismutase, and decrease in interleukin-4 and increase in interleukin-6 content indicating development of oxidative and pro-inflammatory responses. These findings suggest antioxidant and anti-inflammatory therapy as prospective approach for prevention/treatment of perioperative corneal abrasions. The observed anesthesia-induced effects should be considered in any study of ocular surface diseases employing anesthetized animals.
Hazra, Sarbani; Nandi, Sudip; Naskar, Deboki; Guha, Rajdeep; Chowdhury, Sushovan; Pradhan, Nirparaj; Kundu, Subhas C; Konar, Aditya
Successful repair of a damaged corneal surface is a great challenge and may require the use of a scaffold that supports cell growth and differentiation. Amniotic membrane is currently used for this purpose, in spite of its limitations. A thin transparent silk fibroin film from non-mulberry Antheraea mylitta (Am) has been developed which offers to be a promising alternative. The silk scaffolds provide sufficient rigidity for easy handling, the scaffolds support the sprouting, migration, attachment and growth of epithelial cells and keratocytes from rat corneal explants; the cells form a cell sheet, preserve their phenotypes, express cytokeratin3 and vimentin respectively. The films also support growth of limbal stem cell evidenced by expression of ABCG2. The cell growth on the silk film and the amniotic membrane is comparable. The implanted film within the rabbit cornea remains transparent, stable. The clinical examination as well as histology shows absence of any inflammatory response or neovascularization. The corneal surface integrity is maintained; tear formation, intraocular pressure and electroretinography of implanted eyes show no adverse changes. The silk fibroin film from non-mulberry silk worms may be a worthy candidate for use as a corneal scaffold.
Hazra, Sarbani; Nandi, Sudip; Naskar, Deboki; Guha, Rajdeep; Chowdhury, Sushovan; Pradhan, Nirparaj; Kundu, Subhas C.; Konar, Aditya
Purpose: Successful repair of a damaged corneal surface is a great challenge and may require the use of a scaffold that supports cell growth and differentiation. Amniotic membrane is currently used for this purpose, in spite of its limitations. A thin transparent silk fibroin film from non-mulberry Antheraea mylitta (Am) has been developed which offers to be a promising alternative. The silk scaffolds provide sufficient rigidity for easy handling, the scaffolds support the sprouting, migration, attachment and growth of epithelial cells and keratocytes from rat corneal explants; the cells form a cell sheet, preserve their phenotypes, express cytokeratin3 and vimentin respectively. The films also support growth of limbal stem cell evidenced by expression of ABCG2. The cell growth on the silk film and the amniotic membrane is comparable. The implanted film within the rabbit cornea remains transparent, stable. The clinical examination as well as histology shows absence of any inflammatory response or neovascularization. The corneal surface integrity is maintained; tear formation, intraocular pressure and electroretinography of implanted eyes show no adverse changes. The silk fibroin film from non-mulberry silk worms may be a worthy candidate for use as a corneal scaffold. PMID:26908015
Lin, Chien Chen; Ritch, Robert; Lin, Shang Ming; Ni, Mei-Hui; Chang, Yu-Chung; Lu, Yi Lung; Lai, Hong Ji; Lin, Feng-Huei
The purpose of this study is to develop a novel scaffold, derived from fish scales, as an alternative functional material with sufficient mechanical strength for corneal regenerative applications. Fish scales, which are usually considered as marine wastes, were acellularized, decalcified and fabricated into collagen scaffolds. The microstructure of the acellularized scaffold was imaged by scanning electron microscopy (SEM). The acellularization and decalcification treatments did not affect the naturally 3-dimentional, highly centrally-oriented micropatterned structure of the material. To assess the cytocompatibility of the scaffold with corneal cells, rabbit corneal cells were cultured on the scaffold and examined under SEM and confocal microscopy at different time periods. Rapid cell proliferation and migration on the scaffold were observed under SEM and confocal microscopy. The highly centrally-oriented micropatterned structure of the scaffold was beneficial for efficient nutrient and oxygen supply to the cells cultured in the three-dimensional matrices, and therefore it is useful for high-density cell seeding and spreading. Collectively, we demonstrate the superior cellular conductivity of the newly developed material. We provide evidences for the feasibility of the scaffold as a template for corneal cells growth and migration, and thus the fish scale-derived scaffold can be developed as a promising material for tissue-engineering of cornea.
Sharma, Ajay; Mehan, Maneesh M; Sinha, Sunilima; Cowden, John W; Mohan, Rajiv R
Trichostatin A (TSA), a histone deacetylase inhibitor, has been shown to suppress TGF-beta-induced fibrogenesis in many nonocular tissues. The authors evaluated TSA cytotoxicity and its antifibrogenic activity on TGF-beta-driven fibrosis in the cornea with the use of in vitro and in vivo models. Human corneal fibroblasts (HSFs) were used for in vitro studies, and New Zealand White rabbits were used for in vivo studies. Haze in the rabbit cornea was produced with photorefractive keratectomy (PRK) using excimer laser. Trypan blue exclusion and MTT assays evaluated TSA cytotoxicity to the cornea. Density of haze in the rabbit eye was graded with slit lamp biomicroscopy. Real-time PCR, immunoblotting, or immunocytochemistry was used to measure alpha-smooth muscle actin (SMA), fibronectin, and collagen type IV mRNA or protein levels. TUNEL assay was used to detect cell death. TSA concentrations of 250 nM or less were noncytotoxic and did not alter normal HSF morphology or proliferation. TGF-beta1 treatment of HSF significantly increased mRNA and protein levels of SMA (9-fold), fibronectin (2.5-fold), and collagen type IV (2-fold). TSA treatment showed 60% to 75% decreases in TGF-beta1-induced SMA and fibronectin mRNA levels and 1.5- to 3.0-fold decreases in protein levels but had no effect on collagen type IV mRNA or protein levels in vitro. Two-minute topical treatment of TSA on rabbit corneas subjected to -9 D PRK significantly decreased corneal haze in vivo. TSA inhibits TGF-beta1-induced accumulation of extracellular matrix and myofibroblast formation in the human cornea in vitro and markedly decreases haze in rabbit cornea in vivo.
Okumura, Naoki; Kakutani, Kazuya; Inoue, Ryota; Matsumoto, Daiki; Shimada, Tomoki; Nakahara, Makiko; Kiyanagi, Yumiko; Itoh, Takehiro; Koizumi, Noriko
The corneal endothelium maintains corneal transparency by its pump and barrier functions; consequently, its decompensation due to any pathological reason causes severe vision loss due to corneal haziness. Corneal transplantation is the only therapeutic choice for treating corneal endothelial dysfunction, but associated problems, such as a shortages of donor corneas, the difficulty of the surgical procedure, and graft failure, still need to be resolved. Regenerative medicine is attractive to researchers as a means of providing innovative therapies for corneal endothelial dysfunction, as it now does for other diseases. We previously demonstrated the successful regeneration of corneal endothelium in animal models by injecting cultured corneal endothelial cells (CECs) in combination with a Rho kinase (ROCK) inhibitor. The purpose of the present study was to optimize the vehicle for clinical use in cell-based therapy. Our screening of cell culture media revealed that RELAR medium promoted CEC adhesion. We then modified RELAR medium by removing hormones, growth factors, and potentially toxic materials to generate a cell therapy vehicle (CTV) composed of amino acid, salts, glucose, and vitamins. Injection of CECs in CTV enabled efficient engraftment and regeneration of the corneal endothelium in the rabbit corneal endothelial dysfunction model, with restoration of a transparent cornea. The CECs retained >85% viability after a 24 hour preservation as a cell suspension in CTV at 4°C and maintained their potency to regenerate the corneal endothelium in vivo. The vehicle developed here is clinically applicable for cell-based therapy aimed at treating the corneal endothelium. Our strategy involves the generation of vehicle from a culture medium appropriate for a given cell type by removing materials that are not favorable for clinical use. PMID:27355373
Armitage, W John
Currently, cryopreservation is the only method that offers the prospect of truly long-term storage of living cells and tissues. Despite some successful cryopreserved corneal grafts, freezing has been shown to damage the endothelium. When isolated cells are frozen, there are two principal mechanisms of damage: intracellular freezing, which occurs at high cooling rates, and solution effect injury at low cooling rates. When tissues are frozen, there are additional factors that appear to render cells more susceptible to intracellular freezing. Lower cooling rates appear to overcome this when freezing cornea. Vitrification is a way of achieving ice-free cryopreservation, but it also poses considerable challenges owing to the very high solute concentrations required to achieve vitrification at practicable cooling rates. Encouraging results have also been reported for cornea frozen using non-permeating cryoprotectants, which could lead to simpler methods of corneal cryopreservation.
Sharma, S L; Bajaj, R; Sharma, R
510 cases of corneal ulceration were studied for the presence of fungus as a causative organism. Fungus was found in 87 (17.5%) most common fungus found was aspergillus. Mucor was found in 16 cases (18.1%) which is higher than earlier reports. History of trauma specially with vegetative matter and the application of steriods for one purpose or the other is a factor of importance as noted in this study.
Ruggiero, Jason; Keller, Christopher; Porco, Travis; Naseri, Ayman; Sretavan, David W
To develop a rabbit model for continuous curvilinear capsulorhexis (CCC) instruction. University of California San Francisco, San Francisco, California, USA. Experimental study. Isolated rabbit lenses were immersed in 2% to 8% paraformaldehyde (PFA) fixative from 15 minutes to 6 hours. Rabbit eyes were treated by substituting aqueous with 2% to 4% PFA for 30 minutes to 6 hours, followed by washes with a balanced salt solution. Treated lenses and eyes were held in purpose-designed holders using vacuum. A panel of 6 cataract surgeons with 5 to 15 years of experience performed CCC on treated lenses and eyes and responded to a questionnaire regarding the utility of these models for resident teaching using a 5-item Likert scale. The expert panel found that rabbit lenses treated with increasing amounts of fixative simulated CCC on human lens capsules from the third to the seventh decade of life. The panel also found fixative-treated rabbit eyes to simulate some of the experience of CCC within the human anterior chamber but noted a shallower anterior chamber depth, variation in pupil size, and corneal clouding under some treatment conditions. Experienced cataract surgeons who performed CCC on these rabbit models strongly agreed that isolated rabbit lenses treated with fixative provide a realistic simulation of CCC in human patients and that both models were useful tools for capsulorhexis instruction. Results indicate that rabbit lenses treated with 8% PFA for 15 minutes is a model with good fidelity for CCC training. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.
Bromberg, Nancy M
Isobutyl cyanoacrylate tissue adhesive (BCTA) was used in the treatment of refractory superficial corneal ulcers in 17 dogs, one cat, and one rabbit, present 2 weeks to 7 months (mean 6.8 weeks +/- 6.1) prior to referral. Little to no sedation was required in the majority of cases, with only topical anesthetic applied prior to debridement and BCTA application. The presence of the tissue adhesive caused mild discomfort for several days after application, as reported by the owners. The ulcers healed, and the tissue adhesive sloughed in approximately 3 weeks (+/- 1 week). Mild neovascularization of the cornea resolved with topical corticosteroids. The use of BCTA offers a simple, safe and noninvasive treatment for refractory corneal ulcers.
Galvis, Virgilio; Tello, Alejandro; Carreño, Néstor I.; Ortiz, Alvaro I.; Barrera, Rodrigo; Rodriguez, Carlos Julián; Ochoa, Miguel E.
We performed a retrospective interventional case series including 80 eyes of 48 patients with keratoconus (KC) who were treated with modified corneal cross-linking (CXL) for KC (with a partial deepithelization in a pattern of stripes). The average follow-up was 5.8 years (with a minimum of 5 years). At the last follow-up visit, compared with preoperative values, there were no significant changes in spherical equivalent, average keratometry, corneal thickness, corneal hysteresis, or corneal resistance factor. The distance-corrected visual acuity was 20/39 preoperatively and 20/36 postoperatively (P = 0.3). The endothelial cell count decreased by 4.7% (P < 0.005). These findings suggest that this modified corneal CXL technique is a safe and effective alternative to halt the progression of KC up to five years after the procedure. However, some concerns remain as to whether this technique can affect in some degree the corneal endothelial cells. PMID:27199574
Wang, Ling; Lu, Luo
Purpose The purpose of the study is to understand how extracellular stresses, such as ultraviolet (UV) irradiation, affect corneal epithelial cells. Cell volume changes, damage to corneal epithelial integrity, and cellular responses were assessed after exposure to UVC stresses. Methods Primary human and rabbit corneal epithelial cells were exposed to UVC light in culture conditions. Ultraviolet C irradiation–induced changes in cell size and volume were measured by real-time microscopy and self-quenching of the fluorescent dye calcein, respectively. The effects of UVC irradiation on Src and focal adhesion kinase (FAK) phosphorylation and FAK-dependent integrin signaling were detected by ELISA, immunoblotting, and immunostaining. Results Ultraviolet C irradiation induced both size and volume shifts in human and rabbit corneal epithelial cells. Ultraviolet C irradiation-induced decrease of cell volume elicited activation of Src and FAK, characterized by increased phosphorylations of SrcY416, FAKY397, and FAKY925. In addition, immunostaining studies showed UVC irradiation–induced increases in phosphorylation of FAK and formation of integrin β5 clustering. Application of Kv channel blockers, including 4-aminopyridine (4-AP), α-DTX, and depressing substance-1 (BDS-1), effectively suppressed UVC irradiation–induced cell volume changes, and subsequently inhibited UVC irradiation–induced phosphorylation of Src/FAK, and formation of integrin β5 clustering, suggesting UVC irradiation–induced volume changes and Src/FAK activation. Hyperosmotic pressure–induced volume decreases were measured in comparison with effects of UVC irradiation on volume and Src/FAK activation. However, Kv channel blocker, 4-AP, had no effect on hyperosmotic pressure–induced responses. Conclusions The present study demonstrates that UVC irradiation–induced decreases in cell volume lead to Src/FAK activation due to a rapid loss of K ions through membrane Kv channels. PMID:27978555
Dreier, Britta; Thomasy, Sara M; Mendonsa, Rima; Raghunathan, Vijay Krishna; Russell, Paul; Murphy, Christopher J
The transformation of fibroblasts to myofibroblasts is critical to corneal wound healing, stromal haze formation, and scarring. It has recently been demonstrated that the provision of biomimetic substratum topographic cues inhibits the progression toward the myofibroblast phenotype under the influence of transforming growth factor β1 (TGF-β1). The objective of this study was to determine the effect of another fundamental biophysical cue, substrate compliance, on TGF-β1-induced myofibroblast transformation of primary corneal cells isolated from human and rabbit corneas. Human and rabbit corneal fibroblasts were cultured on surfaces of varying substrate compliance (4-71 kPa) and tissue culture plastic (TCP) (> 1 gigapascal [GPa]). Cells were cultured in media containing TGF-β1 at concentrations of 0, 1, or 10 ng/mL for 72 hours. RNA and protein were collected from cells cultured on polyacrylamide gels and TCP and were analyzed for the expression of α-smooth muscle actin (α-SMA), a key marker of myofibroblast transformation, using quantitative PCR, immunocytochemistry, and Western blot. Cells grown on more compliant substrates demonstrated significantly reduced amounts of α-SMA mRNA compared with TCP. Immunocytochemistry and Western blot analysis determining the presence of α-SMA corroborated this finding, thus confirming a reduced transformation to the myofibroblast phenotype on more compliant substrates compared with cells on TCP in the presence of TGF-β1. These data indicate that substrate compliance modulates TGF-β1-induced expression of α-SMA and thus influences myofibroblast transformation in the corneal stroma. This provides further evidence that biomimetic biophysical cues inhibit myofibroblast transformation and participate in stabilizing the native cellular phenotype.
Kim, Cinoo; Kim, Keun Ho; Han, Young Keun; Wee, Won Ryang; Lee, Jin Hak; Kwon, Ji-Won
To investigate the 5-year results of corneal tattooing for cosmetic repair in disfigured eyes and identify the risk factors associated with complications. Corneal tattooing was performed in patients with stable corneal opacity and blind eyes. A total of 147 eyes of 147 patients who were followed up for at least 5 years after tattooing were enrolled in the study. The following valuables were included as potential risk factors for long-term complications: age, sex, duration of opacity before tattooing, and the presence of calcific plaque. Corneal tattooing was also performed in 6 rabbit eyes, and the stained eyes were enucleated at 6 months postoperatively for histological analysis. The average follow-up time after surgery was 65 ± 5 months. Long-term complications such as reopacification or increased opacity, fading of color, and epithelial growth developed in 12% of the tattooed eyes between 2 and 4 years after surgery and most required reoperation. Univariate analysis of risk factors affecting recurrence or complications revealed no statistically significant differences among candidate factors. Histological results of the tattooed rabbit eyes showed that clumps of blackish granules were present in the anterior half of the stroma without any infiltration of inflammatory cells to the adjacent layers. Corneal tattooing in disfigured eyes provided a good cosmetic outcome more than 5 years after surgery.
Bennett, David; Taylor, Zachary; Tewari, Pria; Sung, Sijun; Maccabi, Ashkan; Singh, Rahul; Culjat, Martin; Grundfest, Warren; Hubschman, Jean-Pierre; Brown, Elliott
Terahertz corneal hydration sensing has shown promise in ophthalmology applications and was recently shown to be capable of detecting water concentration changes of about two parts in a thousand in ex vivo corneal tissues. This technology may be effective in patient monitoring during refractive surgery and for early diagnosis and treatment monitoring in diseases of the cornea. In this work, Fuchs dystrophy, cornea transplant rejection, and keratoconus are discussed, and a hydration sensitivity of about one part in a hundred is predicted to be needed to successfully distinguish between diseased and healthy tissues in these applications. Stratified models of corneal tissue reflectivity are developed and validated using ex vivo spectroscopy of harvested porcine corneas that are hydrated using polyethylene glycol solutions. Simulation of the cornea's depth-dependent hydration profile, from 0.01 to 100 THz, identifies a peak in intrinsic reflectivity contrast for sensing at 100 GHz. A 100 GHz hydration sensing system is evaluated alongside the current standard ultrasound pachymetry technique to measure corneal hydration in vivo in four rabbits. A hydration sensitivity, of three parts per thousand or better, was measured in all four rabbits under study. This work presents the first in vivo demonstration of remote corneal hydration sensing.
Pini, Roberto; Basile, Venere; Ambrosini, Stefano; Vannelli, Gabriella; Rossi, Francesca; Menabuoni, Luca; Pratesi, Riccardo; Monici, Monica
Laser welding of corneal tissue is an alternative technique to conventional suturing procedures in ophthalmic surgery. The welding effect is achieved after staining the wound with a chromophore (Indocyanine Green, shortly: ICG) and then irradiating it with a low power diode laser. We present a study on the healing process of corneal wounds using Multispectral Imaging Autofluorescence Microscopy (MIAM). This technique is based on the characterization of fluorescence arising from tissue components (autofluorescence): it is particularly useful in studying corneal tissue, because it is mainly composed of type I collagen, one of the most important endogenous fluorophores. Laser welding tests of the cornea were carried out on rabbits in which full thickness corneal cuts of about 5 mm were sutured using a diode laser emitting at 810 nm, with a power of 80 mW. Bioptic sections of rabbit corneas were examined in a follow up study of 90 days after surgery, and the results were complementary to histological analysis performed in previous studies. Autofluorescence images showed a faster healing process and a better reorganization of the architecture of stromal fibers, in comparison with conventional suturing procedures. MIAM technique can represent a new tool to study the morphology of corneal tissue, offering some real advantages with respect to standard histological analysis. In fact, it does not require any chemical manipulation of the samples, providing information on the biological structure by directly monitoring distribution and emission intensity of endogenous fluorophores.
Wang, Xiaokun; Majumdar, Shoumyo; Ma, Garret; Sohn, Jeeyeon; Yiu, Samuel C; Stark, Walter; Al-Qarni, Awad; Edward, Deepak P; Elisseeff, Jennifer H
To evaluate the crosslinking effect of functionalized chondroitin sulfate (CS) in an ex vivo rabbit cornea model. Chondroitin sulfate molecules were chemically modified with the N-hydroxysuccinimide (NHS) group. Enucleated rabbit eyes were crosslinked with 2, 5, or 10 mg/mL CS-NHS solution for 30 or 60 minutes. The CS-NHS penetration, corneal swelling ratio, Young's modulus, and ultrastructure of the crosslinked corneas were characterized. In addition, rabbit corneas were further treated with a collagenase-chondroitinase solution to create an ex vivo keratoconus (KC)-like model. The KC model corneas were crosslinked with a standard riboflavin-ultraviolet (UV) method or alternatively with CS-NHS. Corneal mechanics, ultrastructure, and keratocyte gene expression were evaluated after UV and CS-NHS crosslinking. CS-NHS effectively penetrated into the corneal stroma within 60 minutes of treatment initiation. CS-NHS crosslinking reduced the swelling ratio by 35%, increased Young's modulus by 20%, and increased collagen fibril diameter and density. CS-NHS crosslinking improved corneal mechanics of KC model corneas to levels comparable to those with UV crosslinking. Moreover, CS-NHS crosslinking demonstrated significant downregulation of proinflammatory gene expression of keratocytes, indicating a potential protective effect imparted by CS-NHS during crosslinking. Our results demonstrated that CS-NHS can reinforce normal and KC model corneal mechanics, and restore collagen density and alignment in KC model corneas without causing extensive keratocyte apoptosis and proinflammatory gene upregulation. Therefore, CS-NHS crosslinking can potentially provide an effective, safe, and biocompatible means of corneal reinforcement.
Kang, Pauline; Swarbrick, Helen
To describe the time course of changes in both peripheral refraction and corneal topography in myopic adults wearing myopic orthokeratology (OK) lenses. Nineteen adult myopes were fitted with OK lenses in both eyes for overnight wear. Central and peripheral refraction and corneal topography were measured along the horizontal meridian at baseline and after 1, 4, 7 and 14 nights of lens wear. At baseline, refraction was myopic at all positions along the horizontal meridian. Two weeks of OK lens wear caused a significant change in refraction where the general trend was a hyperopic shift in spherical equivalent (M) except at 35° in the nasal visual field where there was instead a myopic shift in M. The most significant change in M occurred between baseline and after 1 night of OK lens wear and the effect became less dramatic across subsequent days of OK treatment. Similarly, OK caused significant change in corneal refractive power at all positions along the horizontal corneal chord. There was a reduction in corneal power or flattening of the cornea at all positions except at 2.4 mm and 2.8 mm on the nasal cornea where there was an increase in corneal refractive power or steepening of the cornea. This change was most apparent after 1 night of OK lens wear and, similar to changes in peripheral refraction, changes in corneal refractive power on subsequent days of OK treatment became less marked. Orthokeratology caused significant changes in both peripheral refraction and corneal topography. The greatest change in refraction and corneal refractive power across the horizontal corneal meridian occurred during the first night of OK lens wear. Subsequent changes in both peripheral refraction and corneal topography were less dramatic, in the same manner as reported changes in apical radius and central refraction after OK. This study confirms that with OK treatment, the peripheral retina experiences myopic defocus, which is conjectured to underlie the observed slowing of myopia
Zhou, Hongyan; Kimura, Kazuhiro; Orita, Tomoko; Nishida, Teruo; Sonoda, Koh-Hei
Corneal fibroblasts contribute to collagen remodeling in the corneal stroma in part by mediating collagen degradation. Given that corneal structure is influenced by sex hormone status, we examined the effects of sex hormones on collagen degradation by corneal fibroblasts. Rabbit corneal fibroblasts were cultured in three-dimensional collagen gels with or without sex hormones including 17β-estradiol, progesterone, testosterone, and dehydroepiandrosterone (DHEA). Collagen degradation was determined by measurement of hydroxyproline after acid hydrolysis. The expression and activity of matrix metalloproteinases (MMPs) were evaluated by immunoblot analysis and gelatin zymography. The phosphorylation of mitogen-activated protein kinases (MAPKs) and the nuclear factor-kappa B (NF-κB) inhibitor NF kappa B Inhibitor-alpha (IκB-α) in corneal fibroblasts was examined by immunoblot analysis. Cell proliferation and viability were evaluated by measurement of bromodeoxyuridine incorporation and the release of lactate dehydrogenase, respectively. 17β-Estradiol and progesterone each inhibited interleukin (IL)-1β-induced collagen degradation by corneal fibroblasts in a concentration-dependent manner, whereas testosterone and DHEA had no such effect. MMP expression and activation in corneal fibroblasts exposed to IL-1β were also inhibited by 17β-estradiol and progesterone. These female sex hormones did not affect cell proliferation or viability. Both 17β-estradiol and progesterone inhibited the IL-1β-induced phosphorylation of p38 MAPK without affecting that of the MAPKs extracellular Signal-regulated Kinase (ERK) or c-jun N-terminal kinase (JNK). 17β-Estradiol also inhibited the IL-1β-induced phosphorylation of IκB-α. 17β-Estradiol and progesterone inhibited MMP expression and activity in IL-1β-stimulated corneal fibroblasts and thereby suppressed collagen degradation by these cells.
Pan, Hongwei; Chen, Jiansu; Xu, Jintang; Chen, Miaojiao; Ma, Rong
The transformation of quiescent keratocytes to active phenotypes and the ensuing fibrotic response play important roles in corneal scar formation. This study aims to observe the antifibrotic effect of peroxisome proliferator-activated receptor-gamma (PPARgamma) agonist on corneal fibroblasts cultured in vitro, and to explore the potential application of peroxisome proliferator-activated receptor agonist to the prevention of corneal opacity following wound repair. Rabbit corneal keratocytes were cultured in a medium containing 10% serum to induce their transformation to fibroblasts and myofibroblasts, which are similar to those that repair corneas. After incubation with the PPARgamma agonist pioglitazone at different concentrations, the effect of pioglitazone on the migration, contractility, and viability of corneal fibroblasts was examined. The secretion of matrix metalloproteinase-2 and matrix metalloproteinase-9 was determined by gelatin zymography, and the synthesis of collagen I and fibronectin was investigated by western blotting. Treatment with pioglitazone at concentrations ranging from 1 to 10 mum significantly decreased corneal fibroblast migration, as determined by scrape-wound assay, inhibited corneal fibroblast-induced collagen lattice contraction, and reduced MMP-2 and MMP-9 secretion into the supernatant of cell cultures in a dose-dependent manner. The expression of fibronectin was significantly decreased, while the expression of collagen I was only decreased when treated with 10 mum pioglitazone. Cell viability was not evidently changed compared to the control. This in vitro study demonstrated the anti-fibrotic effect of pioglitazone, suggesting that activation of PPARgamma may be a new approach for the treatment of corneal opacity and scar formation in the corneal wound healing process.
Uematsu, Masafumi; Mohamed, Yasser Helmy; Onizuka, Naoko; Ueki, Ryotaro; Inoue, Daisuke; Fujikawa, Azusa; Kitaoka, Takashi
To develop a device that is capable of easily measuring corneal transepithelial electrical resistance (TER) and changes in the corneal barrier function. We had previously developed an in vivo method for measuring corneal TER using intraocular electrode. This method can be used to precisely measure the decline of the corneal barrier function after instillation of benzalkonium chloride (BAC). In order to lessen the invasiveness of that procedure, we further refined the method for measuring the corneal TER by developing electrodes that could be placed on the cornea and in the conjunctival sac instead of inserting them into the anterior chamber. TER was then calculated by subtracting the electrical resistance, which lacked the corneal epithelial input, from the whole electrical resistance that was measured between the electrodes. Slit lamp examination and scanning electron microscopy (SEM) were used to determine safety of the new device. Corneal TER changes after exposure to 0.02% BAC were determined using the new device as well as SEM and transmission electron microscopy (TEM). Slit lamp examination before and after exposure of rabbits' corneas to the sensor confirmed safety of the device. SEM examination revealed no difference of the corneal epithelium which exposed to the new device with normal corneas. SEM and TEM pictures revealed damaged microvilli and tight junctions after instillation of 0.02% BAC. TER change after treatment with 0.02%BAC was similar to those determined by the established anterior chamber method. We succeeded to develop a less invasive device for corneal TER measurement in vivo in animals. This new device may be applicable in the future for clinical use in humans. Copyright © 2015 Elsevier Inc. All rights reserved.
Nagai, Noriaki; Ito, Yoshimasa; Okamoto, Norio; Shimomura, Yoshikazu
Indomethacin (IMC) has been shown to reduce post-operative inflammation and to decrease intraocular irritation after cataract extraction and in cystoid macular edema; however, the clinical use of its most commonly used eye drops is limited due to topical side-effects that include burning sensation, irritation and epithelial keratitis. It is known that decreasing direct cell stimulation and reducing the amount applied via increasing bioavailability are useful for improving these issues. In this study, we designed ophthalmic formulations containing 0.5% IMC nanoparticles using zirconia beads and Bead Smash 12 (IMCnano eye drops; particle size 76 ± 59 nm, mean ± S.D.), and investigated the corneal toxicity of these IMCnano eye drops. IMCnano eye drops are tolerated better by a human cornea epithelial cell line (HCE-T) than commercially available NDSAIDs preparations (IMC, pranoprofen, diclofenac, bromfenac and nepafenac eye drops), and corneal wound healing in rat eyes with debrided corneal epithelium instilled with IMCnano eye drops is significantly better than that of eyes instilled with commercially available IMC eye drops. In addition, the accumulation of IMC in HCE-T cells treated with the IMCnano eye drops for 30 min was 19.9% that of the accumulation from commercially available IMC eye drops. On the other hand, the corneal penetration of IMC from IMCnano eye drops was significantly greater than in the case of the commercially available IMC eye drops in both in vivo and in vitro studies using rabbit corneas. Taken together, we hypothesize that a nanoparticle formulation reduces the corneal toxicity of IMC eye drops, probably because the accumulation of IMC from IMCnano eye drops in the eye is lower than that from commercially available IMC eye drops. In addition, the nanoparticle formulation may allow a decrease in the amount of IMC used due to the increase in bioavailability, resulting in reduced drug toxicity. These findings provide significant information
Twa, Michael D.; Li, Jiasong; Vantipalli, Srilatha; Singh, Manmohan; Aglyamov, Salavat; Emelianov, Stanislav; Larin, Kirill V.
Corneal collagen cross-linking (CXL) is a clinical treatment for keratoconus that structurally reinforces degenerating ocular tissue, thereby limiting disease progression. Clinical outcomes would benefit from noninvasive methods to assess tissue material properties in affected individuals. Regional variations in tissue properties were quantified before and after CXL in rabbit eyes using optical coherence elastography (OCE) imaging. Low-amplitude (<1µm) elastic waves were generated using micro air-pulse stimulation and the resulting wave amplitude and speed were measured using phase-stabilized swept-source OCE. OCE imaging following CXL treatment demonstrates increased corneal stiffness through faster elastic wave propagation speeds and lower wave amplitudes. PMID:24877005
Luengo Gimeno, Federico; Gatto, Silvia; Ferro, José; Croxatto, Juan Oscar; Gallo, Juan Eduardo
Purpose Platelet-rich plasma (PRP) is an autologous substance with adhesive properties. We aimed at developing and testing the efficacy of a method for PRP preparation in rabbits. Materials and methods An in vitro study was carried out to obtain PRP from forty rabbits and to analyze the number of platelets and type of substance needed to trigger platelet activation. To induce platelet activation, 5%, 10%, 25% and 50% CaCl solutions were used. Then, an in vivo study was performed in twelve rabbits to test PRP adhesiveness in lamellar corneal graft. A control group made up of six rabbits underwent corneal transplantation without using PRP. Results 5% CaCl was the most effective concentration in activating PRP, with a mean time of 19 minutes. An attached corneal flap was seen 3 months after surgery. A detached corneal button was seen in all controls. Conclusion Our method was able to produce rabbit-derived PRP with suitable properties for soft tissue adhesion. These results could be useful for researchers of the growing fields of tissue repair and experimental transplantation. PMID:17005053
Marshall, Kemba L
Using laboratory animal medicine as an established resource, companion animal veterinarians have access to many physiologic and basic science studies that we can now merge with our clinical impressions. By working with reference laboratories, companion animal veterinarians are poised to accelerate our knowledge of the normal rabbit rapidly. The aim of this article is to discuss normal hematopoiesis and infectious and metabolic diseases that specifically target the hemolymphatic system. Additionally, photographic representation of cell types is provided.
Fukuda, Masamichi; Inoue, Amane; Sasaki, Kazuyuki; Takahashi, Nobuo
Pharmacokinetic studies of antibacterial agents for infectious eye diseases have usually been performed on normal rabbit eyes. In this study, the intraocular penetration of fluoroquinolone ophthalmic solutions was determined in normal rabbit eyes and in rabbit eyes that had the corneal epithelium intentionally removed. We determined the intraocular penetration of ofloxacin (OFLX), levofloxacin (LVFX), and norfloxacin (NFLX), fluoroquinolone ophthalmic solutions that are already on the market and undergoing clinical studies, by injecting 50 microl of each solution into the cul-de-sacs of rabbit eyes three times at 15-min intervals. The drug concentration at 10, 30, 60, 120, and 240 min after final instillation was determined by high-performance liquid chromatography. The maximum concentration in the aqueous humor of normal rabbit eyes was 2.09 +/- 1.56 microg/ml (60 min, OFLX), 2.57 +/- 1.00 microg/ml (30 min, LVFX), and 0.42 +/- 0.12 microg/ml (120 min, NFLX). The drug concentration in the aqueous humor of eyes with intentionally removed corneal epithelium was 12.50 +/- 5.62 microg/ml (30 min, OFLX), 9.02 +/- 2.45 microg/ml (60 min, LVFX), and 8.54 +/- 5.17 microg/ml (30 min, NFLX). The drug penetration of the eye drops into eyes with removed corneal epithelium was around 6 times (OFLX), 3.5 times (LVFX), and 20 times (NFLX) higher than the penetration into the eye with normal cornea. Among the pharmacokinetic parameters of the three ophthalmic solutions according to the one-compartment model, the maximum concentration in the aqueous and the area under the concentration-time curve in the aqueous tended to be higher in the eyes with intentionally removed corneal epithelia than in those with normal corneas.
Sun, Yuan; Zhang, Ting; Zhou, Yuehua; Liu, Manli; Zhou, Yugui; Yang, Xiaonan; Weng, Shengbei; To, Chi-Ho; Liu, Quan
To evaluate outcomes, reversibility, and wound healing response after the femtosecond laser-assisted endokeratophakia procedure in a rabbit model. Allogeneic rabbit corneal lenticules were cryopreserved in liquid nitrogen for 3 months. Twenty rabbits underwent the monocular endokeratophakia procedure and were divided into four groups according to the follow-up periods. The first three groups were killed at 3 days, 2 weeks, and 6 months after endokeratophakia, respectively. The rabbits in the fourth group received re-extraction of implanted lenticules at 6 months after endokeratophakia and were killed at 1 month after re-extraction. The rabbits were monitored by slit-lamp microscopy, ultrasonic pachymetry, in vivo confocal microscopy, optical coherence tomography (OCT), Corvis ST tonometry (Oculus Optikgeräte, Wetzlar, Germany), and Ocular Response Analyzer (Reichert Ophthalmic Instruments, Depew, NY). The tissue responses were analyzed by immunohistochemistry and transmission electron microscopy. After endokeratophakia, corneal clarity improved continually with time. The changes in the refraction and corneal thickness were stable after implantation and could be reversed after re-extracting the lenticules. The interfaces were clearly visible on confocal microscopy and transmission electron microscopy images over the entire follow-up period. There were significant numbers of TUNEL-positive keratocytes in lenticules after endokeratophakia. CD11b-positive cells and deposition of fibronectin and tenascin were observed at earlier follow-up times. No alpha-smooth muscle actin-positive fibroblasts could be detected. In addition, the corneal biomechanics parameters were not significantly increased after endokeratophakia. The endokeratophakia procedure using allogeneic cryopreserved lenticules was clinically stable and could be reversed. The wound healing response was mild, limited, and produced no scars. [J Refract Surg. 2016;32(8):569-576.]. Copyright 2016, SLACK
Bai, Jian-Hai; Su, Sheng; Huang, Lei; Zhang, Yan-Yan; Wang, Yun-Song; Guo, Mei-Hua; Yang, Hong-Bin; Cui, Hao
The aim of this study was to optimize reverse iontophoretic (RI) extraction of ferric/ferrous ions from the cornea. Group I consisted of the right eye corneas from 20 normal rabbits. Corneal blood staining was induced in 60 right eyes. The corneal depths from the endothelium to the epithelium layers were divided into three groups by slit-lamp examination: Group II, one-third corneal thickness; Group III, one-half corneal thickness; Group IV, full corneal thickness. RI was performed using vertical diffusion cells. The lower chamber was loaded with glutathione bicarbonate Ringer's buffer (GBR; pH 7.0) or vitamin C (12.5 mg/mL) and GBR (pH 7.0), while the upper chamber was filled with 1 mL GBR. Progress of corneal blood staining removal was evaluated. Application of 1.5 mA to the cornea increased flux by 1.72- and 2.19-fold in Groups III and IV, respectively, but not in Groups I or II, compared to the control. When vitamin C was included, we observed significant flux increases in the controls (1.5-, 2.06-, 2.60-, and 4.59-fold) for Groups I, II, III, and IV, and under RI conditions for Groups III and IV. Following RI, the corneal endothelia appeared similar to corneas from untreated control rabbits, while Draize scores were zero. These results suggested that extracellular ferric/ferrous ions could be extracted from the cornea in vitro by RI, and that vitamin C reduced Fe(3+) to Fe(2+) in the cornea and altered its permselectivity, thus increasing the RI contribution to iron extraction.
Tandon, Ashish; Sharma, Ajay; Rodier, Jason T; Klibanov, Alexander M; Rieger, Frank G; Mohan, Rajiv R
This study examined the effects of BMP7 gene transfer on corneal wound healing and fibrosis inhibition in vivo using a rabbit model. Corneal haze in rabbits was produced with the excimer laser performing -9 diopters photorefractive keratectomy. BMP7 gene was introduced into rabbit keratocytes by polyethylimine-conjugated gold nanoparticles (PEI2-GNPs) transfection solution single 5-minute topical application on the eye. Corneal haze and ocular health in live animals was gauged with stereo- and slit-lamp biomicroscopy. The levels of fibrosis [α-smooth muscle actin (αSMA), F-actin and fibronectin], immune reaction (CD11b and F4/80), keratocyte apoptosis (TUNEL), calcification (alizarin red, vonKossa and osteocalcin), and delivered-BMP7 gene expression in corneal tissues were quantified with immunofluorescence, western blotting and/or real-time PCR. Human corneal fibroblasts (HCF) and in vitro experiments were used to characterize the molecular mechanism mediating BMP7's anti-fibrosis effects. PEI2-GNPs showed substantial BMP7 gene delivery into rabbit keratocytes in vivo (2×10(4) gene copies/ug DNA). Localized BMP7 gene therapy showed a significant corneal haze decrease (1.68±0.31 compared to 3.2±0.43 in control corneas; p<0.05) in Fantes grading scale. Immunostaining and immunoblot analyses detected significantly reduced levels of αSMA (46±5% p<0.001) and fibronectin proteins (48±5% p<0.01). TUNEL, CD11b, and F4/80 assays revealed that BMP7 gene therapy is nonimmunogenic and nontoxic for the cornea. Furthermore, alizarin red, vonKossa and osteocalcin analyses revealed that localized PEI2-GNP-mediated BMP7 gene transfer in rabbit cornea does not cause calcification or osteoblast recruitment. Immunofluorescence of BMP7-transefected HCFs showed significantly increased pSmad-1/5/8 nuclear localization (>88%; p<0.0001), and immunoblotting of BMP7-transefected HCFs grown in the presence of TGFβ demonstrated significantly enhanced pSmad-1/5/8 (95%; p<0.001) and
Tandon, Ashish; Sharma, Ajay; Rodier, Jason T.; Klibanov, Alexander M.; Rieger, Frank G.; Mohan, Rajiv R.
This study examined the effects of BMP7 gene transfer on corneal wound healing and fibrosis inhibition in vivo using a rabbit model. Corneal haze in rabbits was produced with the excimer laser performing -9 diopters photorefractive keratectomy. BMP7 gene was introduced into rabbit keratocytes by polyethylimine-conjugated gold nanoparticles (PEI2-GNPs) transfection solution single 5-minute topical application on the eye. Corneal haze and ocular health in live animals was gauged with stereo- and slit-lamp biomicroscopy. The levels of fibrosis [α-smooth muscle actin (αSMA), F-actin and fibronectin], immune reaction (CD11b and F4/80), keratocyte apoptosis (TUNEL), calcification (alizarin red, vonKossa and osteocalcin), and delivered-BMP7 gene expression in corneal tissues were quantified with immunofluorescence, western blotting and/or real-time PCR. Human corneal fibroblasts (HCF) and in vitro experiments were used to characterize the molecular mechanism mediating BMP7’s anti-fibrosis effects. PEI2-GNPs showed substantial BMP7 gene delivery into rabbit keratocytes in vivo (2×104 gene copies/ug DNA). Localized BMP7 gene therapy showed a significant corneal haze decrease (1.68±0.31 compared to 3.2±0.43 in control corneas; p<0.05) in Fantes grading scale. Immunostaining and immunoblot analyses detected significantly reduced levels of αSMA (46±5% p<0.001) and fibronectin proteins (48±5% p<0.01). TUNEL, CD11b, and F4/80 assays revealed that BMP7 gene therapy is nonimmunogenic and nontoxic for the cornea. Furthermore, alizarin red, vonKossa and osteocalcin analyses revealed that localized PEI2-GNP-mediated BMP7 gene transfer in rabbit cornea does not cause calcification or osteoblast recruitment. Immunofluorescence of BMP7-transefected HCFs showed significantly increased pSmad-1/5/8 nuclear localization (>88%; p<0.0001), and immunoblotting of BMP7-transefected HCFs grown in the presence of TGFβ demonstrated significantly enhanced pSmad-1/5/8 (95%; p<0.001) and
Li, Fang; Hao, Peng; Liu, Guangjie; Wang, Weiyi; Han, Ruifang; Jiang, Zhixin; Li, Xuan
To investigate the effects of hyaluronic acid (HA) on the inflammation of corneal fibroblasts induced by lipopolysaccharide (LPS). Primary rabbit corneal keratocytes were isolated with collagenase. The keratocytes were cultured in a serum-containing medium to induce corneal fibroblasts, which represented the wound repair phenotype of corneal keratocytes. Corneal fibroblasts were treated with LPS with or without 4-methylumbelliferone (4-MU) / high molecular weight hyaluronic acid (HMWHA). The gene expression was evaluated via real-time PCR, immunofluorescence, and western blot. The release of inflammatory cytokines and HA was determined by ELISA. Three types of hyaluronan synthase (HAS) were detected in corneal fibroblasts. LPS stimulation caused the up-regulation of HAS1 and HAS2 expression in corneal fibroblasts. LPS-induced HAS2 expression was significantly inhibited by 4-MU, and accompanied by decreased HA release by the corneal fibroblasts. In the corneal fibroblasts, 4-MU reduced the LPS-stimulated up-regulation of inflammatory cytokines including IL-1, IL-6, IL-8, TNF-α, and also attenuated the LPS-induced up-regulation of inflammatory related receptors including TLR2, TLR4, CD44, and CXCR1. HMWHA treatment resulted in a significant decline in the expression of IL-6, IL-8, TLR4, and CXCR1 responded to LPS stimulation. Consistent with mRNA expression of level, the up-regulation of the release of IL-6 and IL-8 induced by LPS in corneal fibroblasts was significantly attenuated by 4-MU and HMWHA. The LPS-induced expression of IL-8 and its receptor CXCR1 at both the mRNA and protein level were significantly attenuated by 4-MU and HMWHA. The inhibitor of HA synthesis 4-MU, and HMWHA successfully reduced LPS-induced inflammation in corneal fibroblasts. The mechanism might be via the inhibition of LPS-induced TLR4 up-regulation.
Li, Zhiwei; Wang, Yumeng; Xu, Yanyun; Jhanji, Vishal; Zhang, Chunxiao; Mu, Guoying
To evaluate the fragility of cornea after UVA/riboflavin crosslinking (CXL). Sixty New Zealand rabbits received UVA/riboflavin crosslinking treatment (wavelength 365 nm, irradiance 3.0 mW/cm, and total dose 5.4 J/cm) on right eyes. Animals were sacrificed before and immediately after treatment (day 0), day 1, 3, 7, and 28 after treatment. A 4×10 mm corneal strip for biomechanical evaluation was harvested after sacrifice. The corneal fragility was evaluated by measurement of elongation rate, whereby the elongation rate equals elongation length/baseline length. The Youngs modulus and maximal stress were 1.41±0.51 MPa and 5.56±1.84 MPa before CXL, and increased to 2.31±0.68 MPa (P=0.008) and 9.25±2.74 MPa (P=0.04), respectively, on day 0, then maintained a stable level within a 28 days follow-up. The elongation rate was 62.04±9.34% before CXL and decreased to 48.95%±8.24% (P=0.02) on day 0, then maintained a stable level within a 28 days follow-up. This study showed an increase in the corneal fragility after UVA/riboflavin crosslinking along with an increase in the corneal stiffness. A long-term follow-up should be taken to evaluate the potential deleterious effect of the increasing corneal fragility after UVA/riboflavin crosslinking.
Kim, Yoo C.; Grossniklaus, Hans E.; Edelhauser, Henry F.; Prausnitz, Mark R.
Purpose. This study tested the hypothesis that highly targeted intrastromal delivery of bevacizumab using coated microneedles allows dramatic dose sparing compared with subconjunctival and topical delivery for treatment of corneal neovascularization. Methods. Stainless steel microneedles 400 μm in length were coated with bevacizumab. A silk suture was placed in the cornea approximately 1 mm from the limbus to induce corneal neovascularization in the eyes of New Zealand white rabbits that were divided into different groups: untreated, microneedle delivery, topical eye drop, and subconjunctival injection of bevacizumab. All drug treatments were initiated 4 days after suture placement and area of neovascularization was measured daily by digital photography for 18 days. Results. Eyes treated once with 4.4 μg bevacizumab using microneedles reduced neovascularization compared with untreated eyes by 44% (day 18). Eyes treated once with 2500 μg bevacizumab using subconjunctival injection gave similar results to microneedle-treated eyes. Eyes treated once with 4.4 μg subconjunctival bevacizumab showed no significant effect compared with untreated eyes. Eyes treated with 52,500 μg bevacizumab by eye drops three times per day for 14 days reduced the neovascularization area compared with untreated eyes by 6% (day 18), which was significantly less effective than the single microneedle treatment. Visual exam and histological analysis showed no observable effect of microneedle treatment on corneal transparency or microanatomical structure. Conclusions. This study shows that microneedles can target drug delivery to corneal stroma in a minimally invasive way and demonstrates effective suppression of corneal neovascularization after suture-induced injury using a much lower dose compared with conventional methods. PMID:25212779
Howes, E.L.; Cruse, V.K.; Kwok, M.T.
A severe keratitis can be produced after the direct injection of bacterial endotoxin, or lipopolysaccharide (LPS), in rabbits. Corneal inflammation can progress to scarring and vascularization within a 2 to 3 week period. Pretreatment with systemic adrenal corticosteroids (triamcinolone) prevents this response. Limbal cellular and vascular events were studied during the first 20 hr after injection of LPS in treated and nontreated rabbits. Perivascular limbal inflammatory cells were counted and limbal vascular permeability was assessed by extravasation of 131I-albumin and 125I-fibrinogen in the cornea. Corticosteroids decreased but did not prevent the early protein extravasation and profoundly altered the inflammatory cell population around blood vessels at the limbus. Mononuclear cells, particularly mononuclear phagocytes, were sharply reduced. It is proposed that these cell types play an important role in the perpetuation and amplification of the inflammatory response in this reaction.
Baehr, E. F. (Inventor)
A corneal seal device is provided which, when placed in an incision in the eye, permits the insertion of a surgical tool or instrument through the device into the eye. The device includes a seal chamber which opens into a tube which is adapted to be sutured to the eye and serves as an entry passage for a tool. A sealable aperture in the chamber permits passage of the tool through the chamber into the tube and hence into the eye. The chamber includes inlet ports adapted to be connected to a regulated source of irrigation fluid which provides a safe intraocular pressure.
Whitson, Jess T; Cavanagh, H Dwight; Lakshman, Neema; Petroll, W Matthew
The corneal toxicity of 2 intraocular pressure-lowering agents was compared in a rabbit cornea model with New Zealand White rabbits. Corneal epithelial morphology and cell size were assessed by in vivo confocal microscopy. Baseline microscopic examinations were performed on 1 eye of each animal. Two weeks later, the eyes were bathed for 3 min in travoprost 0.004% preserved without benzalkonium chloride (BAK( or latanoprost 0.005% preserved with 0.02% BAK; the eyes were then rinsed with balanced salt solution, and the corneas were again examined by confocal microscopy (n=4/group). A second group of animals was exposed to the medications through a dosing regimen of 1 drop/min (lpar3 drops total) (n=4/group). In eyes treated with travoprost without BAK (3-min bath), superficial epithelial cells were similar to baseline, as indicated by their visible cell borders and bright nuclei. In contrast, the surface cells in eyes treated with latanoprost were significantly smaller and brighter and had less distinct borders. Surface cell size was significantly smaller as compared with baseline size and as compared with rabbits treated with travoprost without BAK for 3 min. Similar effects on corneal epithelial cell morphology were observed with the 1-drop/min dosing regimen. In this rabbit model, travoprost 0.004% preserved without BAK did not cause corneal epithelial toxicity; latanoprost 0.005% induced superficial cell loss, most likely caused by the presence of a relatively high concentration of BAK (0.02%).
Dawson, Emma; Maino, Anna; Lee, John
Corneal tattoos have been previously used in managing corneal pathologies. We describe a case of a 28-year-old male who presented with intractable binocular diplopia, which was relieved with a corneal tattoo. This is a novel application of corneal tattooing for the alleviation of intractable binocular diplopia.
Farooq, Asim V; Soin, Ketki; Williamson, Samantha; Joslin, Charlotte E; Cortina, Maria S; Tu, Elmer Y
To report the association of chronic ocular hypotony with the development of progressive corneal ectasia and hydrops. Retrospective case series. Three patients with ocular hypotony were referred for corneal evaluation and found to have ectasia and acute corneal hydrops in their hypotonous eye(s). Clinically, the globes were easily deformable with either external digital palpation and/or simple blinking. All 3 patients had a history of chronic iridocyclitis, including one with juvenile idiopathic arthritis. In each case, the area of thinning was narrow and arcuate in configuration, distinctive from other ectatic disorders. Also uncharacteristically, the acute hydrops resolved rapidly within 2 to 3 weeks without surgical intervention. In 1 case, severe thinning with perforation occurred requiring urgent penetrating keratoplasty. This case series demonstrates a unique clinical entity in which corneal ectasia and hydrops developed in the setting of ocular hypotony and easily deformable corneas, in a pattern unlike previously described forms of ectasia. Acute hydrops, even with associated corneal perforation, demonstrated a short and self-limited course. Corneal ectasia and irregular astigmatism should be suspected as a cause of unexplained visual loss in the ever-increasing number of patients with chronic, stable ocular hypotony. Further study is warranted to determine the pathophysiology of corneal ectasia in this setting, which may include mechanical and inflammatory factors.
Higuchi, Akihiro; Inoue, Hiroyoshi; Kaneko, Yoshio; Oonishi, Erina; Tsubota, Kazuo
The ocular surface is strongly affected by oxidative stress, which causes many ocular diseases including dry eye. Previously, we showed that selenium compounds, e.g., selenoprotein P and Se-lactoferrin, were candidates for treatment of dry eye. This paper shows the efficacy of Se-lactoferrin for the treatment of dry eye compared with Diquas as a control drug using two dry eye models and incorporation of lactoferrin into corneal epithelial cells via lactoferrin receptors. We show the efficacy of Se-lactoferrin eye drops in the tobacco smoke exposure rat dry eye model and short-term rabbit dry eye model, although Diquas eye drops were only effective in the short-term rabbit dry eye model. These results indicate that Se-lactoferrin was useful in the oxidative stress-causing dry eye model. Se-lactoferrin was taken into corneal epithelium cells via lactoferrin receptors. We identified LRP1 as the lactoferrin receptor in the corneal epithelium involved in lactoferrin uptake. Se-lactoferrin eye drops did not irritate the ocular surface of rabbits. Se-lactoferrin was an excellent candidate for treatment of dry eye, reducing oxidative stress by a novel mechanism.
Higuchi, Akihiro; Inoue, Hiroyoshi; Kaneko, Yoshio; Oonishi, Erina; Tsubota, Kazuo
The ocular surface is strongly affected by oxidative stress, which causes many ocular diseases including dry eye. Previously, we showed that selenium compounds, e.g., selenoprotein P and Se-lactoferrin, were candidates for treatment of dry eye. This paper shows the efficacy of Se-lactoferrin for the treatment of dry eye compared with Diquas as a control drug using two dry eye models and incorporation of lactoferrin into corneal epithelial cells via lactoferrin receptors. We show the efficacy of Se-lactoferrin eye drops in the tobacco smoke exposure rat dry eye model and short-term rabbit dry eye model, although Diquas eye drops were only effective in the short-term rabbit dry eye model. These results indicate that Se-lactoferrin was useful in the oxidative stress-causing dry eye model. Se-lactoferrin was taken into corneal epithelium cells via lactoferrin receptors. We identified LRP1 as the lactoferrin receptor in the corneal epithelium involved in lactoferrin uptake. Se-lactoferrin eye drops did not irritate the ocular surface of rabbits. Se-lactoferrin was an excellent candidate for treatment of dry eye, reducing oxidative stress by a novel mechanism. PMID:27833152
Koprowski, Robert; Lanza, Michele; Irregolare, Carlo
Efficacy and high availability of surgery techniques for refractive defect correction increase the number of patients who undergo to this type of surgery. Regardless of that, with increasing age, more and more patients must undergo cataract surgery. Accurate evaluation of corneal power is an extremely important element affecting the precision of intraocular lens (IOL) power calculation and errors in this procedure could affect quality of life of patients and satisfaction with the service provided. The available device able to measure corneal power have been tested to be not reliable after myopic refractive surgery. Artificial neural networks with error backpropagation and one hidden layer were proposed for corneal power prediction. The article analysed the features acquired from the Pentacam HR tomograph, which was necessary to measure the corneal power. Additionally, several billion iterations of artificial neural networks were conducted for several hundred simulations of different network configurations and different features derived from the Pentacam HR. The analysis was performed on a PC with Intel(®) Xeon(®) X5680 3.33 GHz CPU in Matlab(®) Version 22.214.171.1244 (R2010b) with Signal Processing Toolbox Version 7.1 (R2010b), Neural Network Toolbox 7.0 (R2010b) and Statistics Toolbox (R2010b). A total corneal power prediction error was obtained for 172 patients (113 patients forming the training set and 59 patients in the test set) with an average age of 32 ± 9.4 years, including 67% of men. The error was at an average level of 0.16 ± 0.14 diopters and its maximum value did not exceed 0.75 dioptres. The Pentacam parameters (measurement results) providing the above result are tangential anterial/posterior. The corneal net power and equivalent k-reading power. The analysis time for a single patient (a single eye) did not exceed 0.1 s, whereas the time of network training was about 3 s for 1000 iterations (the number of neurons in the hidden layer was 400).
Enders, Philip; Holtick, Udo; Schaub, Friederike; Tuchscherer, Armin; Hermann, Manuel M; Scheid, Christoph; Cursiefen, Claus; Bachmann, Björn O
To assess the capability of Scheimpflug-based densitometry of the cornea to quantify light chain deposits in patients with active monoclonal gammopathies. This is a case-control study in which data from a leading tertiary university center in myeloma care were analyzed. Ten eyes of 5 patients with monoclonal gammopathy and 26 eyes of 13 healthy controls undergoing clinical evaluation and Scheimpflug-based measurements were included in the study. The main outcome measures were densitometry data of the 4 corneal layers-anterior layer (AL), central layer (CL), posterior layer, and total layer (TL)-in 4 different annuli (central annular zone 0-2 mm, intermediate annular zone 2-6 mm, peripheral annular zone 6-10 mm, and total annular zone 0-12 mm). In 8 eyes of 4 patients with IgG-based gammopathy, corneal light backscatter was highest in the AL and decreased with increasing corneal depth. The peripheral annular zone showed a higher densitometry value compared with the corneal center. Compared with healthy controls, the AL (P < 0.001), the CL (P < 0.001), and the TL (P < 0.001) had significantly higher corneal light backscatter in patients with gammopathy in the total and the peripheral annular zones. In one patient with predominantly IgA-based disease, corneal light backscatter was not elevated. Scheimpflug-based densitometry of the cornea is able to quantify opacification by immunoglobulin G light chain deposits in monoclonal gammopathies. This noninvasive technique can complement presently used in vivo confocal microscopy and corneal photography to objectivize corneal changes. Densitometry might allow monitoring of corneal immunoglobulin deposits in follow-up examinations.
Zhou, Hongyan; Kimura, Kazuhiro; Orita, Tomoko; Nishida, Teruo; Sonoda, Koh-Hei
To examine the effect of medroxyprogesterone 17-acetate (MPA) on interleukin-1β (IL-1β)-induced collagen degradation by corneal fibroblasts. Rabbit corneal fibroblasts were cultured in three-dimensional collagen gels with or without MPA. Collagen degradation was determined by measurement of hydroxyproline after acid hydrolysis. The expression or activity of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) was evaluated by immunoblot analysis or gelatin zymography. The phosphorylation of mitogen-activated protein kinases (MAPKs) in corneal fibroblasts was examined by immunoblot analysis. Cell proliferation and viability were evaluated by measurement of bromodeoxyuridine incorporation and the release of lactate dehydrogenase, respectively. MPA inhibited IL-1β-induced collagen degradation by corneal fibroblasts in a concentration- and time-dependent manner. MMP expression and activation as well as TIMP expression in corneal fibroblasts exposed to IL-1β were also inhibited by MPA. MPA had no effect on cell proliferation or viability. MPA inhibited the IL-1β-induced phosphorylation of p38 MAPK without affecting that of the MAPKs ERK or JNK. IL-1β-induced MMP expression and activation as well as collagen degradation were also blocked by the p38 MAPK inhibitor SB203580. MPA inhibited MMP expression and thereby suppressed collagen degradation by corneal fibroblasts induced by IL-1β. Furthermore, inhibition of p38 MAPK phosphorylation by MPA may contribute to its inhibition of collagen degradation.
Kim, Kyoung Woo; Park, Soo Hyun; Lee, Soo Jin; Kim, Jae Chan
To maintain corneal transparency, corneal endothelial cells (CECs) exert a pump function against aqueous inflow. However, human CECs are arrested in the G1-phase and non-proliferative in vivo. Thus, treatment of corneal endothelial decompensation is limited to corneal transplantation, and grafts are vulnerable to immune rejection. Here, we show that ribonuclease (RNase) 5 is more highly expressed in normal human CECs compared to decompensated tissues. Furthermore, RNase 5 up-regulated survival of CECs and accelerated corneal endothelial wound healing in an in vitro wound of human CECs and an in vivo cryo-damaged rabbit model. RNase 5 treatment rapidly induced accumulation of cytoplasmic RNase 5 into the nucleus, and activated PI3-kinase/Akt pathway in human CECs. Moreover, inhibition of nuclear translocation of RNase 5 using neomycin reversed RNase 5-induced Akt activation. As a potential strategy for proliferation enhancement, RNase 5 increased the population of 5-bromo-2′-deoxyuridine (BrdU)-incorporated proliferating CECs with concomitant PI3-kinase/Akt activation, especially in CECs deprived of contact-inhibition. Specifically, RNase 5 suppressed p27 and up-regulated cyclin D1, D3, and E by activating PI3-kinase/Akt in CECs to initiate cell cycle progression. Together, our data indicate that RNase 5 facilitates corneal endothelial wound healing, and identify RNase 5 as a novel target for therapeutic exploitation. PMID:27526633
Knotts, F. B.; Cook, M. L.; Stevens, J. G.
Herpes simplex virus (HSV) type 1 induces a long-standing latent infection in the central nervous system of mice and rabbits. The infection was extablished in the brain stems of rabbits after corneal inoculation of the virus, and in the spinal cords of mice after rear footpad infection. In these animals, infectious virus could not be recovered by direct isolation from tissues; it was detected only after the tissues were maintained as organ cultures in vitro. PMID:4353820
Kadhim, Yasir Jawad; Farhood, Qasim K
Background Central corneal thickness (CCT) is an important indicator of corneal status. Its measurement provides valid information about corneal physiological condition and possible changes associated with diseases, traumas, and hypoxia. It is an integral part for interpretation of intraocular pressure and glaucoma patient management and in prerefractive procedure assessment. Objective The aim of this study is to determine the mean CCT among a normal Iraqi population and to correlate between CCT and age, gender, refraction, and corneal curvature. Patients and methods This cross-sectional study was carried out at Ibn Al-Haitham Teaching Eye Hospital. A total of 418 eyes from 209 healthy individuals with an age range from 20 to 75 years were studied. CCT was measured by ultrasound pachymeter. Refraction was measured using an auto-refractor and confirmed by trial lenses and retinoscopy to calculate the spherical equivalent. Corneal curvature was measured using an auto-refracto-keratometer to calculate the average corneal curvature (AVK). Results The mean CCT was 543.95±32.58 μm with a range from 422 to 636 μm. CCT was not affected by gender. CCT significantly negatively correlated with age and AVK. CCT significantly positively correlated with the spherical equivalence. Conclusion and recommendation Among an Iraqi population, CCT significantly decreased with age. Myopics had significantly thinner corneas. There was weak but significant negative correlation between CCT and corneal curvature. We recommend further studies about the relationship between central corneal thickness and other ocular parameters in Iraqi population such as the axial length. PMID:27932859
Khachikian, Stephen S; Belin, Michael W; Ciolino, Joseph B
To establish the normal distribution for intrasubject (right eye/left eye) central corneal pachymetry in a refractive surgery population. A retrospective analysis was performed on 1448 eyes of 724 consecutive patients evaluated for refractive surgery. Pachymetric data were obtained from the Pentacam Eye Scanner. Right and left eye pachymetry values were compared for the corneal apex, pupil center, and thinnest point. Statistical analysis was performed to determine normal levels of variance. The average apex reading was 539.3+/-36.8 microm, median 542 microm, and mode 539 microm (range: 411 to 664 microm). Values for the pupil center (average 538.7 microm) and thinnest point (average 536.1 microm) followed a similar distribution. The average pachymetry difference between fellow eyes was 8.8+/-7.2 microm at the apex, 8.9+/-8.3 microm at the pupil center, and 9.0+/-8.3 microm at the thinnest region. Individuals with a greater than 23.2 microm apical pachymetry difference represent less than 5% of the population. Individuals with an apical difference greater than 30.4 microm represent less than 0.5%. Pachymetric asymmetry outside the normal range should alert the clinician to examine for other parameters that are more established refractive surgery risk factors.
Meek, Keith M.; Knupp, Carlo
The corneal stroma plays several pivotal roles within the eye. Optically, it is the main refracting lens and thus has to combine almost perfect transmission of visible light with precise shape, in order to focus incoming light. Furthermore, mechanically it has to be extremely tough to protect the inner contents of the eye. These functions are governed by its structure at all hierarchical levels. The basic principles of corneal structure and transparency have been known for some time, but in recent years X-ray scattering and other methods have revealed that the details of this structure are far more complex than previously thought and that the intricacy of the arrangement of the collagenous lamellae provides the shape and the mechanical properties of the tissue. At the molecular level, modern technologies and theoretical modelling have started to explain exactly how the collagen fibrils are arranged within the stromal lamellae and how proteoglycans maintain this ultrastructure. In this review we describe the current state of knowledge about the three-dimensional stromal architecture at the microscopic level, and about the control mechanisms at the nanoscopic level that lead to optical transparency. PMID:26145225
Meek, Keith M; Knupp, Carlo
The corneal stroma plays several pivotal roles within the eye. Optically, it is the main refracting lens and thus has to combine almost perfect transmission of visible light with precise shape, in order to focus incoming light. Furthermore, mechanically it has to be extremely tough to protect the inner contents of the eye. These functions are governed by its structure at all hierarchical levels. The basic principles of corneal structure and transparency have been known for some time, but in recent years X-ray scattering and other methods have revealed that the details of this structure are far more complex than previously thought and that the intricacy of the arrangement of the collagenous lamellae provides the shape and the mechanical properties of the tissue. At the molecular level, modern technologies and theoretical modelling have started to explain exactly how the collagen fibrils are arranged within the stromal lamellae and how proteoglycans maintain this ultrastructure. In this review we describe the current state of knowledge about the three-dimensional stromal architecture at the microscopic level, and about the control mechanisms at the nanoscopic level that lead to optical transparency. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.
Camellin, Massimo; Guidotti, Jacopo Maria; Arba Mosquera, Samuel
To evaluate the efficacy and safety of Corneal-Wavefront guided transepithelial photorefractive keratectomy (TransPRK) after corneal collagen cross linking (CXL) in keratoconic patients. In this retrospective, non-comparative, consecutive case series, 39 keratoconic eyes underwent Corneal-Wavefront guided TransPRK for the correction of aberrations at least 4 months after conventional CXL at SEKAL Rovigo Microsurgery Centre, Rovigo, Italy. Two eyes (5%) underwent a secondary laser retreatment for the improvement of post-operative visual acuity and were not included in this retrospective analysis. The mean age of the patients was 35±12 years (19-64 years) at the time of the surgery. Keratron-Scout (Optikon) topographer was used for diagnostic tests and a flying-spot laser (AMARIS; SCHWIND eye-tech-solutions) was used for the refractive surgery. Complete ophthalmic examinations were performed before and after the surgery (4-36 months postoperatively with a mean follow up time of 10±8 months). Preoperatively, eyes showed irregular astigmatism up to 8D. At last postoperative follow-up, 21 eyes (57%) had UDVA better than 20/40, and six eyes (16%) had UDVA of 20/20. Twenty-three eyes (62%) were within 1.50D of attempted correction in spherical equivalent (mean deviation from target was +1.09±2.36D, range -2.50 to +7.38D). No eye lost 2 Snellen lines of CDVA, and 15 eyes (41%) had an increase of more than 2 lines. Corneal-Wavefront guided transepithelial PRK ablation profiles after conventional CXL yields to good visual, optical, and refractive results. These treatments are safe and efficacious for the correction of refracto-therapeutic problems in keratoconic patients. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.
Mimura, Tatsuya; Yokoo, Seiichi; Yamagami, Satoru
Human corneal endothelial cells (HCECs) do not replicate after wounding. Therefore, corneal endothelial deficiency can result in irreversible corneal edema. Descemet stripping automated endothelial keratoplasty (DSAEK) allows selective replacement of the diseased corneal endothelium. However, DSAEK requires a donor cornea and the worldwide shortage of corneas limits its application. This review presents current knowledge on the tissue engineering of corneal endothelium using cultured HCECs. We also provide our recent work on tissue engineering for DSAEK grafts using cultured HCECs. We reconstructed DSAEK grafts by seeding cultured DiI-labelled HCECs on collagen sheets. Then HCEC sheets were transplanted onto the posterior stroma after descemetorhexis in the DSAEK group. Severe stromal edema was detected in the control group, but not in the DSAEK group throughout the observation period. Fluorescein microscopy one month after surgery showed numerous DiI-labelled cells on the posterior corneal surface in the DSAEK group. Frozen sections showed a monolayer of DiI-labelled cells on Descemet’s membrane. These findings indicate that cultured adult HCECs, transplanted with DSAEK surgery, maintain corneal transparency after transplantation and suggest the feasibility of performing DSAEK with HCECs to treat endothelial dysfunction. PMID:24955745
Torricelli, Andre A M; Santhanam, Abirami; Wu, Jiahui; Singh, Vivek; Wilson, Steven E
The corneal wound healing response, including the development of stromal opacity in some eyes, is a process that often leads to scarring that occurs after injury, surgery or infection to the cornea. Immediately after epithelial and stromal injury, a complex sequence of processes contributes to wound repair and regeneration of normal corneal structure and function. In some corneas, however, often depending on the type and extent of injury, the response may also lead to the development of mature vimentin+ α-smooth muscle actin+ desmin+ myofibroblasts. Myofibroblasts are specialized fibroblastic cells generated in the cornea from keratocyte-derived or bone marrow-derived precursor cells. The disorganized extracellular matrix components secreted by myofibroblasts, in addition to decreased expression of corneal crystallins in these cells, are central biological processes that result in corneal stromal fibrosis associated with opacity or "haze". Several factors are associated with myofibroblast generation and haze development after PRK surgery in rabbits, a reproducible model of scarring, including the amount of tissue ablated, which may relate to the extent of keratocyte apoptosis in the early response to injury, irregularity of stromal surface after surgery, and changes in corneal stromal proteoglycans, but normal regeneration of the epithelial basement membrane (EBM) appears to be a critical factor determining whether a cornea heals with relative transparency or vision-limiting stromal opacity. Structural and functional abnormalities of the regenerated EBM facilitate prolonged entry of epithelium-derived growth factors such as transforming growth factor β (TGF-β) and platelet-derived growth factor (PDGF) into the stroma that both drive development of mature myofibroblasts from precursor cells and lead to persistence of the cells in the anterior stroma. A major discovery that has contributed to our understanding of haze development is that keratocytes and corneal
Wang, Feng-yun; Lu, Xiao-he; Zhang, Cai-xia; Bai, Lang; Zhang, Jing; Zhong, Yan-yan; Wang, Shuang-shuang
To evaluate the impact of hyphema secondary to high intraocular pressure on corneal pathology in rabbits. Thirty adult New Zealand rabbit were randomized into 3 equal groups, and in each rabbit, one eye served as the experimental eye with the other as the control eye. In the experimental eye, autoblood was injected into the anterior chamber to induce high intraocular pressure maintained for 3, 5, or 8 days. Only saline was injected into the control eye. After the injections, the cornea was observed with slit-lamp microscopy, and at 3, 5, or 8 days, the experimental and control eyes were taken from the 3 groups for microscopic examination of the corneas to detect the occurrence of cornea bloodstain with prolonged high intraocular pressure. Corneal edema, elastic fibers changes, growth of new blood vessels, changes of eosinophils, fibroblasts, lymphocytes and plasma cells, as well as the pathological changes of the corneal layers were observed and compared between the experimental and control eyes. Maintenance of high intraocular pressure for 8 days resulted in the most severe corneal edema and thickening, and histopathologically, the corneal stroma showed widened space between the elastic fibers and obvious fiber distortion. Neovascularization was seen in the marginal cornea where eosinophil infiltration occurred with a small number of lymphocytes, plasma cells and fiber cells. All the three groups showed more obvious edema in the posterior than in the anterior cornea. Prolonged hyphema with ocular hypertension results in aggravation of corneal edema, and corneal blood staining does not occur until 8 days of high intraocular pressure but corneal elastic fiber disruption can be seen, suggesting the impending irreversible pathological changes of cornea.
Clarkson, D M; Phillips, C I
The extraction of the rabbit lens is described using a 25 G irrigating needle and a 22 G aspirating needle; at the latter's bevelled tip lens fragmentation occurs due to the longitudinal ultrasonic vibrations generated there--an 'acoustic horn' causes the tip to vibrate with large amplitudes. The use of small needles allows considerable manoeuvrability in the anterior chamber and usually eliminates the need for corneal suturing. Push-pull coupled syringes equate the volume of irrigation with that of aspiration. This procedure makes possible lens extraction through an aperture in the anterior capsule of the rabbit's lens and a similar machine is being constructed for trial on human cataract. Images PMID:1009054
Whitcher, J. P.; Srinivasan, M.; Upadhyay, M. P.
Diseases affecting the cornea are a major cause of blindness worldwide, second only to cataract in overall importance. The epidemiology of corneal blindness is complicated and encompasses a wide variety of infectious and inflammatory eye diseses that cause corneal scarring, which ultimately leads to functional blindness. In addition, the prevalence of corneal disease varies from country to country and even from one population to another. While cataract is responsible for nearly 20 million of the 45 million blind people in the world, the next major cause is trachoma which blinds 4.9 million individuals, mainly as a result of corneal scarring and vascularization. Ocular trauma and corneal ulceration are significant causes of corneal blindness that are often underreported but may be responsible for 1.5-2.0 million new cases of monocular blindness every year. Causes of childhood blindness (about 1.5 million worldwide with 5 million visually disabled) include xerophthalmia (350,000 cases annually), ophthalmia neonatorum, and less frequently seen ocular diseases such as herpes simplex virus infections and vernal keratoconjunctivitis. Even though the control of onchocerciasis and leprosy are public health success stories, these diseases are still significant causes of blindness--affecting a quarter of a million individuals each. Traditional eye medicines have also been implicated as a major risk factor in the current epidemic of corneal ulceration in developing countries. Because of the difficulty of treating corneal blindness once it has occurred, public health prevention programmes are the most cost-effective means of decreasing the global burden of corneal blindness. PMID:11285665
Goswami, Dinesh G; Tewari-Singh, Neera; Dhar, Deepanshi; Kumar, Dileep; Agarwal, Chapla; Ammar, David A; Kant, Rama; Enzenauer, Robert W; Petrash, J Mark; Agarwal, Rajesh
Purpose To evaluate the toxic effects and associated mechanisms in corneal tissue exposed to vesicating agent, nitrogen mustard (NM), a bi-functional alkylating analog of chemical warfare agent sulfur mustard (SM). Methods Toxic effects and associated mechanisms were examined in maximal affected corneal tissue employing corneal cultures and human corneal epithelial (HCE) cells exposed to nitrogen mustard (NM). Results Analysis of ex vivo rabbit corneas showed that NM exposure increased apoptotic cell death, epithelial thickness, epithelial-stromal separation and levels of VEGF, COX-2 and MMP-9. In HCE cells, NM exposure resulted in a dose-dependent decrease in cell viability and proliferation, which was associated with DNA damage in terms of an increase in p53 ser15, total p53 and H2A.X ser139 levels. NM exposure also induced caspase-3 and PARP cleavage, suggesting their involvement in NM-induced apoptotic death in rabbit cornea and HCE cells. Similar to rabbit cornea, NM exposure caused an increase in COX-2, MMP-9 and VEGF levels in HCE cells, indicating a role of these molecules and related pathways in NM-induced corneal inflammation, epithelial-stromal separation and neovascularization. NM exposure also induced activation of AP-1 transcription factor proteins and upstream signaling pathways including MAPKs and Akt, suggesting that these could be key factors involved in NM-induced corneal injury. Conclusion Results from this study provide insight into the molecular targets and pathways that could be involved in NM-induced corneal injuries laying the background for further investigation of these pathways in vesicant–induced ocular injuries, which could be helpful in the development of targeted therapies. PMID:26555588
Knappe, S; Stachs, O; Guthoff, R
Wearing orthokeratology contact lenses (OCL, Hecht-see free; Hecht, Germany) overnight can change corneal refraction by up to -4.5 dioptre (dpt) based on corneal adaptation to the double reverse surface of the OCL. This allows a temporary independence on glasses or contact lenses. It is known that the central corneal thickness decreases while the corneal thickness in the periphery probably increases. The aim of this study was to investigate the corneal changes of volunteers wearing OCL with in vivo confocal microscopy. Five young adults (mean 22.8 years, three female, two male) with low to moderate myopia (range -1.75 to -3.5 dpt; sphere equivalent -2.7+/-0.59 dpt) were fitted with OCL of reverse-geometry design in both eyes. Lenses were worn in both eyes overnight and were removed immediately in the morning. The volunteers were examined with in vivo confocal microscopy using a combination of Heidelberg retina tomograph II and the Rostock cornea module before wearing the OCL and after the 1(st), 3(rd), 5(th), 7(th), 13(th), 20(th) and 25(th) nights. The central and mid-peripheral total corneal thickness as well as the epithelial thickness were examined in the morning between 7.30 am and 9.30 am. The central and the mid-peripheral epithelial corneal thickness was reduced significantly (p<0.05) from day 1 to the 13(th) day. This stabilized later until the the examination was concluded. No significant changes (p>0.05) were found in the central or mid-peripheral total corneal thickness after 25 days of wearing the OCL. Wearing OCL leads to a reduction in the central corneal epithelial thickness. Our inability to find an increase in mid-peripheral total and epithelial corneal thickness may be because the expected increase of the mid-peripheral cornea is limited to a defined area, which makes repeated measurements at a particular point difficult.
Maharana, Prafulla K; Dubey, Aditi; Jhanji, Vishal; Sharma, Namrata; Das, Sujata; Vajpayee, Rasik B
Corneal ectasias include a group of disorders characterised by progressive thinning, bulging and distortion of the cornea. Keratoconus is the most common disease in this group. Other manifestations include pellucid marginal degeneration, Terrien's marginal degeneration, keratoglobus and ectasias following surgery. Advanced ectasias usually present with loss of vision due to high irregular astigmatism. Management of these disorders is difficult due to the peripheral location of ectasia and associated severe corneal thinning. Newer contact lenses such as scleral lenses are helpful in a selected group of patients. A majority of these cases requires surgical intervention. This review provides an update on the current treatment modalities available for management of advanced corneal ectasias.
Vinciguerra, Paolo; Mencucci, Rita; Romano, Vito; Spoerl, Eberhard; Camesasca, Fabrizio I; Favuzza, Eleonora; Azzolini, Claudio; Mastropasqua, Rodolfo; Vinciguerra, Riccardo
To compare biomechanical effect, riboflavin penetration and distribution in transepithelial corneal collagen cross-linking with iontophoresis (I-CXL), with standard cross linking (S-CXL) and current transepithelial protocol (TE-CXL). The study was divided into two different sections, considering, respectively, rabbit and human cadaver corneas. In both sections corneas were divided according to imbibition protocols and irradiation power. Imaging mass spectrometry by matrix-assisted laser desorption/ionization (MALDI-IMS) and stress-strain measurements were used. Forty-eight rabbit and twelve human cadaver corneas were evaluated. MALDI-IMS showed a deep riboflavin penetration throughout the corneal layers with I-CXL, with a roughly lower concentration in the deepest layers when compared to S-CXL, whereas with TE-CXL penetration was considerably less. In rabbits, there was a significant increase (by 71.9% and P = 0.05) in corneal rigidity after I-CXL, when compared to controls. In humans, corneal rigidity increase was not significantly different among the subgroups. In rabbits, I-CXL induced a significant increase in corneal stiffness as well as better riboflavin penetration when compared to controls and TE-CXL but not to S-CXL. Stress-strain in human corneas did not show significant differences among techniques, possibly because of the small sample size of groups. In conclusion, I-CXL could be a valid alternative to S-CXL for riboflavin delivery in CXL, preserving the epithelium.
Lim, Chris H L; Turner, Angus; Lim, Blanche X
Published audits have demonstrated that corneal abrasions are a common presenting eye complaint. Eye patches are often recommended for treating corneal abrasions despite the lack of evidence for their use. This systematic review was conducted to determine the effects of the eye patch when used to treat corneal abrasions. The objective of this review was to assess the effects of patching for corneal abrasion on healing and pain relief. We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 4), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to May 2016), EMBASE (January 1980 to May 2016), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to May 2016), System for Information on Grey Literature in Europe (OpenGrey) (January 1995 to May 2016), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), 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. We last searched the electronic databases on 9 May 2016. We also searched the reference lists of included studies, unpublished 'grey' literature and conference proceedings and contacted pharmaceutical companies for details of unpublished trials. We included randomised and quasi-randomised controlled trials that compared patching the eye with no patching to treat simple corneal abrasions. Two authors independently assessed the risk of bias and extracted data. Investigators were contacted for further information regarding the quality of trials. The primary outcome was healing at 24, 48 and 72 hours while secondary outcomes included measures of pain, quality of life and adverse effects. We graded the certainty of the evidence using GRADE. We included 12 trials which
Rosahn, Paul D.; Hu, Ch'uan-K'uei
Observations on an epidemic of rabbit pox occurring in an isolated animal room during the winter of 1933–34 are reported. The clinical manifestations, consisting of a generalized papular eruption involving the skin and mucous membranes, together with blepharitis, ophthalmia, nasal discharge and lymphadenopathy were essentially similar to those noted in a pox epidemic of the previous year. This was true in general also of the pathological findings except that vacuolization, local necrosis and vesicle formation were seen in the epidermis, while in the previous year the microscopic pathology in the skin was confined to the corium. Evidence was presented indicating that the infection can be transmitted through the medium of a personal carrier, and that transmission in this manner can occur during the incubation period or before a definite diagnosis is possible. The findings also demonstrated that the etiological agents responsible for the disease reported here and that of the previous year were immunologically related, and that the immunity in recovered animals effectively persisted during the entire period for which data are available, 9 to 12 months. It appeared also that young animals suckling an immune doe were more refractory to the development of the lesions of rabbit pox than were the young of susceptible does. PMID:19870418
Basu, P K; Avaria, M; Jankie, R
We have studied in rabbits the effect of subconjunctivally injected hydrocortisone on the polymorphonuclear leucocyte invasion of corneal wounds at different times after an injury. One group of rabbits was treated with the steroid (hydrocortisone group) and the other not (control group). After making nonpenetrating trephine incisions on the cornea we obtained cellular samples by the impression technique at a given postoperative period (2, 4, or 6 hours), and then the animal was killed. The cornea was processed for histological study of the infiltrating cells. At any postoperative period the number of polymorphonuclear leucocytes in the corneal wounds of the hydrocortisone group was significantly less than the number in the identical wounds of the control group (p less than 0.01 to 0.001). Images PMID:7317321
SHAHRAKI, Kourosh; HOSSEINI, Seyed-Rafi; AMINI FARD, Atefeh; SHADEMAN, Hashem; SHAHRAKI, Kianoush; SALARI, Amir Masood; AMINI FARD, Mohammad-Naeim
We aimed to compare the therapeutic effects of topical 1% sodium hyaluronate (Healon) or hydroxypropyl methylcellulose (HPMC) for the treatment of alkali-induced epithelial corneal defects. An alkali burn was produced in 30 corneas of 30 New Zealand White rabbits, using a 7.5-mm-diameter trephine. The rabbits were randomly divided into three groups. Four times a day, one group was treated with 1% sodium hyaluronate, one with HPMC, and one (the control group) with physiologic saline. During the treatment period, the size of the epithelial defect was observed every day, up to day 17, using a slit-lamp biomicroscope (with fluorescein). Sodium hyaluronate significantly accelerated the wound healing process compared with saline and increased the healing rate to an even greater extent compared with HPMC. Sodium hyaluronate, but not HPMC, is an effective wound-healing adjuvant for alkali-induced corneal epithelial defects.
Crooke, Almudena; Guzman-Aranguez, Ana; Mediero, Aranzazu; Alarma-Estrany, Pilar; Carracedo, Gonzalo; Pelaez, Teresa; Peral, Assumpta; Pintor, Jesús
We have investigated the effect of melatonin and its analogues on rabbit corneal epithelial wound healing. New Zealand rabbits were anaesthetised and wounds were made by placing Whatman paper discs soaked in n-heptanol on the cornea. Melatonin and analogues (all 10 nmol) were instilled. Wound diameter was measured every 2 hours by means of fluorescein application with a Topcon SL-8Z slit lamp. Melatonin antagonists (all 10 nmol) were applied 2 hours before the application of the n-heptanol-soaked disc and then every 6 hours together with melatonin. To confirm the presence of MT2 receptors in corneal epithelial cells immunohistochemistry, Western blot and RT-PCR assays in native tissue and in rabbit corneal epithelial cells were performed. The tear components were extracted then processed by HPLC to quantify melatonin in tears. Migration assays revealed that melatonin and particularly the treatment with the MT2 agonist IIK7, accelerated the rate of healing (p < 0.001). The application of the non-selective melatonin receptor antagonist luzindole and the MT2 antagonist DH97 (but not prazosin), prevented the effect of melatonin on wound healing (both p < 0.001). Immunohistochemistry, Western blot and RT-PCR assays showed the presence of MT2 melatonin receptor in corneal epithelial cells. In addition, we have identified melatonin in tears and determined its daily variations. These data suggest that MT2 receptors are implicated in the effect of melatonin on corneal wound healing regulating migration rate. This suggests the potential use of melatonin and its analogues to enhance epithelial wound healing in ocular surface disease.
Liu, Xian-Ning; Zhu, Xiu-Ping; Wu, Jie; Wu, Zheng-Jie; Yin, Yong; Xiao, Xiang-Hua; Su, Xin; Kong, Bin; Pan, Shi-Yin; Yang, Hua; Cheng, Yan; An, Na; Mi, Sheng-Li
AIM To assess acellular ostrich corneal matrix used as a scaffold to reconstruct a damaged cornea. METHODS A hypertonic saline solution combined with a digestion method was used to decellularize the ostrich cornea. The microstructure of the acellular corneal matrix was observed by transmission electron microscopy (TEM) and hematoxylin and eosin (H&E) staining. The mechanical properties were detected by a rheometer and a tension machine. The acellular corneal matrix was also transplanted into a rabbit cornea and cytokeratin 3 was used to check the immune phenotype. RESULTS The microstructure and mechanical properties of the ostrich cornea were well preserved after the decellularization process. In vitro, the methyl thiazolyl tetrazolium results revealed that extracts of the acellular ostrich corneas (AOCs) had no inhibitory effects on the proliferation of the corneal epithelial or endothelial cells or on the keratocytes. The rabbit lamellar keratoplasty showed that the transplanted AOCs were transparent and completely incorporated into the host cornea while corneal turbidity and graft dissolution occurred in the acellular porcine cornea (APC) transplantation. The phenotype of the reconstructed cornea was similar to a normal rabbit cornea with a high expression of cytokeratin 3 in the superficial epithelial cell layer. CONCLUSION We first used AOCs as scaffolds to reconstruct damaged corneas. Compared with porcine corneas, the anatomical structures of ostrich corneas are closer to those of human corneas. In accordance with the principle that structure determines function, a xenograft lamellar keratoplasty also confirmed that the AOC transplantation generated a superior outcome compared to that of the APC graft. PMID:27158598
Chu, Hsiao-Sang; Lin, Chung-Tien; Chow, Lu-Ping; Chen, Chih-Ta; Hu, Fung-Rong
Purpose To evaluate the effects and underlying mechanisms of early and late subconjunctival injection of bevacizumab on the inhibition of corneal neovascularization (NV). Methods Corneal NV was induced by closed eye contact lens wear followed by a silk suture tarsorrhaphy in rabbits. Weekly subconjunctival injections of bevacizumab (5.0 mg) for 1 month were started immediately (early treatment group) or 1 month after induction of corneal NV with continuous induction (late treatment group). The severity of corneal NV was evaluated. Immunostaining was used to evaluate the intracorneal diffusion of bevacizumab, and the existence of pericytes and smooth muscle cells around the NV. The expression of AM-3K, an anti-macrophage antibody, vascular endothelial growth factor (VEGF) with its receptors (VEGFR1 and VEGFR2), and vascular endothelial apoptosis were also evaluated. Western blot analysis was performed to quantify the expression level of VEGF, VEGFR1 and VEGFR2 on corneal epithelium and stroma in different groups. Results Early treatment with bevacizumab inhibited corneal NV more significantly than late treatment. Intracorneal diffusion of bevacizumab was not different among different groups. Immunostaining showed pericytes and smooth muscle cells around newly formed vessels as early as 2 weeks after induction. Immunostaining and Western blot analysis showed that VEGF, VEGFR1, and VEGFR2 on corneal stroma increased significantly in no treatment groups and late treatment groups, but not in early treatment group. Bevacizumab significantly inhibited macrophage infiltration in the early but not late treatment group. Sporadic vascular endothelial apoptosis was found at 4 weeks in the late but not early treatment group. Conclusions Early but not late injection of bevacizumab inhibited corneal NV. Late injection of bevacizumab did not alter macrophage infiltration, and can't inhibit the expression of VEGF, VEGFR1, and VEGFR2 on corneal vessels. The inhibition of corneal NV
Uematsu, Masafumi; Kumagami, Takeshi; Shimoda, Kenichiro; Kusano, Mao; Teshima, Mugen; To, Hideto; Kitahara, Takashi; Kitaoka, Takashi; Sasaki, Hitoshi
To determine the element that modulates benzalkonium chloride (BAC) toxicity by using a new electrophysiological method to evaluate acute corneal barrier dysfunction induced by travoprost Z with sofZia (Travatan Z(®)), travoprost with 0.015% BAC (Travatan(®)), and its additives. Corneal transepithelial electrical resistance (TER) was measured in live white Japanese rabbits by 2 Ag/AgCl electrodes placed in the anterior aqueous chamber and on the cornea. We evaluated corneal TER changes after a 60-s exposure to travoprost Z, travoprost, and 0.015% BAC. Similarly, TER changes were evaluated after corneas were exposed for 60 s to the travoprost additives ethylenediaminetetraacetic acid disodium salt, boric acid, mannitol, trometamol, and polyoxyethylene hydrogenated castor oil 40 (HCO-40) with or without BAC. Corneal damage was examined after exposure to BAC with or without travoprost additives using scanning electron microscopy (SEM) and a cytotoxicity assay. Although no decreases of TER were noted after exposure to travoprost Z with sofZia and travoprost with 0.015% BAC, a significant decrease of corneal TER was observed after 0.015% BAC exposure. With the exception of BAC, no corneal TER decreases were observed for any travoprost additives. After corneal exposure to travoprost additives with BAC, HCO-40 was able to prevent the BAC-induced TER decrease. SEM observations and the cytotoxicity assay confirmed that there was a remarkable improvement of BAC-induced corneal epithelial toxicity after addition of HCO-40 to the BAC. Travoprost Z with sofZia and travoprost with BAC do not induce acute corneal barrier dysfunction. HCO-40 provides protection against BAC-induced corneal toxicity.
Dean, B S; Krenzelok, E P
Cyanoacrylate-containing adhesives such as Super Glue, Krazy Glue, and a vast array of artificial nail adhesives are monomers which rapidly polymerize and bond in the presence of water or weak bases. Inadvertent contact with skin or tissue can also cause rapid bonding with resultant irritation. To assess the magnitude of problems associated with ocular contamination involving cyanoacrylates, a 12-month prospective study was conducted. 34 cases (21 adult and 13 pediatric) were collected. In all cases, contaminated eyes were thoroughly irrigated with tepid water for 15 minutes. 15 patients (44%) suffered a corneal abrasion, as determined by ophthalmic exam, necessitating treatment with antibiotics, cycloplegics, and patching. Individuals reporting complete resolution were irrigated with 20 minutes of exposure, while patients suffering mechanical injury delayed decontamination for a minimum of 15 minutes. In addition to immediate irrigation of eyes exposed to cyanoacrylates, we recommend an ophthalmologic evaluation to rule out the possibility of mechanical injury.
Niederkorn, Jerry Y.
Corneal transplants have been successfully performed in human subjects for over 100 years and enjoy an immune privilege that is unrivaled in the field of transplantation. Immune privilege is defined as the reduced incidence and tempo in the immune rejection of corneal allografts compared to other categories of organ allografts performed under the same conditions. Skin allografts transplanted across various MHC or minor histocompatibility barriers undergo rejection in approximately 100% of the hosts. By contrast, orthotopic corneal allografts experience long-term survival in 50% to >90% of the hosts, depending on the histocompatibility barriers that confront the host. The capacity of corneal allografts to evade immune rejection is attributable to multiple anatomical, physiological, and immunoregulatory conditions that conspire to prevent the induction and expression of alloimmunity. PMID:23360158
Brunette, Isabelle; Sherknies, Denis; Terry, Mark A; Chagnon, Miguel; Bourges, Jean-Louis; Meunier, Jean
To characterize the 3-D corneal shape deformation incurred by Fuchs corneal dystrophy and pseudophakic bullous keratopathy by using the integrated analysis of Orbscan (Bausch & Lomb Surgical, Rochester, NY) topographic maps of affected and normal corneas. One hundred thirty-seven patients with Fuchs dystrophy or pseudophakic keratopathy were divided into three groups according to the severity of the disease: mild (central corneal thickness [CCT], 500-710 μm; n = 46); moderate (710-775 μm; n = 45), and severe (775-1100 μm; n = 46). A control group included 411 normal subjects matched for age and refractive spherical equivalent (three control subjects for each subject with Fuchs or pseudophakic keratopathy). The four groups were compared by using 3-D corneal shape atlases illustrating mean anterior elevation, posterior elevation, and pachymetry. Whereas the atlases showed little anterior surface deformation, the posterior surface presented a significant central bulging toward the anterior chamber. The thinnest point was displaced away from the center, toward the superior nasal midperiphery. The corneal periphery remained relatively unaffected by the disease, except in the final stage. 3-D atlases provided detailed new information on the 3-D corneal shape deformation incurred by Fuchs corneal dystrophy throughout disease progression.
Theophanous, Christos; Jacobs, Deborah S; Hamrah, Pedram
To illustrate that corneal neuralgia may be the basis for refractory dry eye syndrome after laser-assisted in situ keratomileusis (LASIK). The methodology used is that of a retrospective medical record review of a small case series. Three male patients, aged 30 to 48 years, referred in 2012 for dry eye syndrome refractory to treatment within 1 year of LASIK or LASIK enhancement are reported. Each patient gave history of eye pain, light sensitivity, and difficulty with visual activities beginning within 2 months of LASIK or LASIK enhancement. Best-corrected visual acuity was 20/15 or 20/20 in each of the six eyes. Tear-centered models and metrics did not explain persistent symptoms, which was consistent with inadequate response to standard dry eye treatments used before referral and reported here. In vivo confocal microscopy was abnormal at presentation in each case and was followed over time. Treatments undertaken subsequent to referral included autologous serum tears (three cases), PROSE (Prosthetic Replacement of the Ocular Surface Ecosystem) treatment (two cases), and systemic agents for pain, anxiety, or depression (three cases). By the end of 2013, at a mean of 23 months after LASIK or LASIK enhancement, symptoms improved in all three patients. Patients with persistent dry eye symptoms out of proportion to clinical signs after LASIK have a syndrome that may best be classified as corneal neuralgia. In vivo confocal microscopy can be informative as to the neuropathic basis of this condition. In keeping with current understanding of complex regional pain syndrome, early multimodal treatment directed toward reducing peripheral nociceptive signaling is warranted to avoid subsequent centralization and persistence of pain. Distinguishing this syndrome from typical post-LASIK dry eye remains a challenge.
Samoilă, O; Totu, Lăcrămioara; Călugăru, M
A variety of corneal pathology can lead to corneal ulcers and perforations. A deep corneal ulcer may need surgical treatment to allow good volume restoration and reepithelisation. Corneal perforation must be sealed and when the perforation is large, the task of repairing the defect can be underwhelming. The elegant solution is the corneal transplant, but this is not always readily available, especially in undeveloped countries. We present here two cases with different solutions to seal the perforated cornea: the first one has a large peripheral defect and it is successfully sealed with scleral patch and the second one is central with small perforation and is successfully sealed with multilayered amniotic membrane. Both cases are followed for over 12 months and demonstrate good corneal restoration (both on clinical examination and corneal topography). Sclera and amniotic membrane can be used to seal corneal defects when corneal transplant is not readily available.
Hamdy Abdelaziz, Mohamed; Fouad Ghoneim, Dina; Abdelkawi Ahmed, Salwa; Taher, Ibraheim Mohyeldin; Abdel-Salam, Ahmed Medhat
Recurrent corneal erosion occurs when the wounded corneal epithelium failed to adhere to the underlying stroma. Therefore, this work aimed to assess the effect of treatment of corneal injury using Q- switched Nd:YAG laser. Twenty one New Zealand male rabbits weighing 2-2.5 kg and 3 months old were classified into three main groups. The control group: did not received any treatment (n=3 rabbits). The rest of the animals (n= 18 rabbits), corneal epithelium was injured by syringe needle and blade 15 and divided into:(A) Normal healing group: which was divided into three subgroups (n=3 rabbits each), and the animals were left for normal healing for1 day, 1 week, and 4 weeks respectively, (B) Laser treated group: divided into three subgroups (n=3 rabbit seach) and subjected to anterior stromal puncture using Q-switched Nd: YAG laser on corneal sub-epithelium or superficial stroma, and the animals were left for 1 day, 1 week, and 4 weeksrespectively. After the demonstrated periods, the corneas were isolated for estimation of total protein content, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), total antioxidative capacity (TAC), total oxidative capacity (TOC) and oxidative stress index (OSI). The present results of corneal total protein showed increment in the percentage change in normal healed groups after 1 day, 1 week and 4 weeks by values of 93%, 68% and 39%. In Q-switched Nd: YAG laser treated group the results showed better improvement in corneal protein than normal healed group with percentage changes of 58%, 29%, and 7.5% respectively. In SDS- PAGE, a protein band at 110 KD appeared in the migrating epithelium for both normal healed group and Q-switched Nd:YAG laser treated group with changes in the peaks intensities at middle and low molecular weight regions. Moreover, after 4 weeks the peak at 110 KD disappeared in the wounded epithelium treated with Q-switched Nd:YAG. After four weeks, the OSI in laser treated corneas showed pronounced
Hamdy Abdelaziz, Mohamed; Fouad Ghoneim, Dina; Abdelkawi Ahmed, Salwa; Taher, Ibraheim Mohyeldin; Abdel- Salam, Ahmed Medhat
Introduction: Recurrent corneal erosion occurs when the wounded corneal epithelium failed to adhere to the underlying stroma. Therefore, this work aimed to assess the effect of treatment of corneal injury using Q- switched Nd:YAG laser. Method: Twenty one New Zealand male rabbits weighing 2-2.5 kg and 3 months old were classified into three main groups. The control group: did not received any treatment (n=3 rabbits). The rest of the animals (n= 18 rabbits), corneal epithelium was injured by syringe needle and blade 15 and divided into:(A) Normal healing group: which was divided into three subgroups (n=3 rabbits each), and the animals were left for normal healing for1 day, 1 week, and 4 weeks respectively, (B) Laser treated group: divided into three subgroups (n=3 rabbit seach) and subjected to anterior stromal puncture using Q-switched Nd: YAG laser on corneal sub-epithelium or superficial stroma, and the animals were left for 1 day, 1 week, and 4 weeksrespectively. After the demonstrated periods, the corneas were isolated for estimation of total protein content, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), total antioxidative capacity (TAC), total oxidative capacity (TOC) and oxidative stress index (OSI). Results: The present results of corneal total protein showed increment in the percentage change in normal healed groups after 1 day, 1 week and 4 weeks by values of 93%, 68% and 39%. In Q-switched Nd: YAG laser treated group the results showed better improvement in corneal protein than normal healed group with percentage changes of 58%, 29%, and 7.5% respectively. In SDS- PAGE, a protein band at 110 KD appeared in the migrating epithelium for both normal healed group and Q-switched Nd:YAG laser treated group with changes in the peaks intensities at middle and low molecular weight regions. Moreover, after 4 weeks the peak at 110 KD disappeared in the wounded epithelium treated with Q-switched Nd:YAG. After four weeks, the OSI in laser
Savino, Gustavo; Battendieri, Remo; Riso, Monica; Traina, Salvatore; Poscia, Andrea; DʼAmico, Giovanni; Caporossi, Aldo
To evaluate the corneal topography and the topographic changes after ptosis surgery on patients affected by congenital and acquired blepharoptosis. Twenty eyes of 17 patients affected by acquired and congenital ptosis underwent surgical correction through anterior levator complex tightening. Computerized tomography (Syrius Sistem; CSO) was used to analyze any change in corneal astigmatism (CYL), simulated keratometry, anterior corneal symmetry index front, apical keratometry front, and central corneal thickness. Visual acuity, margin reflex distance, and levator function were also measured. After surgical ptosis repair, corneal topography demonstrated a reduction in average keratometry of 0.15 ± 0.47 diopters (D) and in corneal astigmatism of 0.26 ± 1.12 D. Significant differences were found in apical keratometry front (-1.84 ± 1.76 D) and in best-corrected visual acuity (-0.18 ± 0.06 logMAR) in the postoperative examinations. Central corneal thickness did not show significant differences between preoperative and postoperative examinations. Postoperative topographic maps showed a reduction of symmetry index front (0.10 ± 0.64 D). Eyelid ptosis modifies anterior corneal surface inducing refractive errors and modifying corneal astigmatism in patients, thus affecting the quality of vision. The surgical correction of blepharoptosis induces anterior corneal surface modification, restoring corneal symmetry and regular corneal astigmatism. Postoperative corneal topography showed normal corneal contours.
Williams, Keryn A; Irani, Yazad D
Despite ever-increasing understanding of the genetic underpinnings of many corneal dystrophies, gene therapy designed to ameliorate disease has not yet been reported in any human patient. In this review, we explore the likely reasons for this apparent failure of translation. We identify the requirements for success: the genetic defect involved must have been identified and mapped, vision in the affected patient must be significantly impaired or likely to be impaired, no better or equivalently effective treatment must be available, the treatment must be capable of modulating corneal pathology, and delivery of the construct to the appropriate cell must be practicable. We consider which of the corneal dystrophies might be amenable to treatment by genetic manipulations, summarize existing therapeutic options for treatment, and explore gene editing using clustered regularly interspaced short palindromic repeat/Cas and other similar transformative technologies as the way of the future. We then summarize recent laboratory-based advances in gene delivery and the development of in vitro and in vivo models of the corneal dystrophies. Finally, we review recent experimental work that has increased our knowledge of the pathobiology of these conditions.
Lee, Eun Kyoung; Kwon, Ji-Won; Hyon, Joon Young; Han, Young Keun
To evaluate the levels of satisfaction among physicians who have undergone corneal refractive surgery. This study included 212 eyes of 107 consecutive patients who underwent laser in situ keratomileusis or laser sub-epithelial keratomileusis surgery. Patients were divided into two groups: one group of physicians and one group of other healthcare workers (HCWs). The physicians' group was also subdivided into two different groups: surgeons or doctors using microscopes and medical physicians. The main outcome measures were scale scores obtained by using the Visual Function Index-14 questionnaires; uncorrected distance visual acuity (UDVA), residual spherical equivalent (SE), optical zone diameter, and residual corneal thickness were also compared between the groups. No significant differences in preoperative parameters, with the exception of the ratio of types of refractive surgery, were noted between the physicians and the HCWs group. Additionally, no differences between the groups were noted in the postoperative UDVA, residual SE, optical zone diameter, residual corneal thickness, and level of satisfaction. When comparing the two subgroups of physicians, the differences in satisfaction rates were not statistically significant, even in terms of the performance of delicate manual work. No statistically significant differences in the clinical outcomes and satisfaction scores were detected after surgery between the physicians and HCWs groups, nor were any significant differences detected between the surgeons and medical physicians groups. Corneal refractive surgery can conceivably be recommended even for physicians who perform intensive near vision-dependent activities and delicate operations.
Leonard, Brian C; Yañez-Soto, Bernardo; Raghunathan, Vijay Krishna; Abbott, Nicholas L; Murphy, Christopher J
Mucins are large glycoproteins expressed by epithelial cells of both the conjunctiva and cornea, and principle components of the glycocalyx. They are thought to play an important role in determining the interactions between the cornea/conjunctiva and the overlying tear film. The purpose of this study was to characterize the membrane-associated corneal mucin expression pattern from multiple species commonly used in ophthalmic research and drug development to better define the biochemical attributes of the ocular surface. Humans, rhesus macaques and dogs were found to have a very similar pattern of mucin expression, with mucin 16 (MUC16) being the most prevalent mucin transcript. In contrast, the rabbit had a unique mucin expression pattern with all mucin transcripts expressed at relatively similar levels. To determine if there were spatial differences in expression, peripheral and central corneal epithelium were individually isolated and evaluated for mucin expression. In all species examined, MUC1, MUC4 and MUC16 had higher peripheral corneal expression when compared with central, which reached statistical significance in MUC1 (rhesus and dog). The data demonstrated variation in corneal epithelial membrane-associated mucin expression between species, with the rabbit having a distinct expression pattern. These differences may be reflective of the environment, pathogen exposure or tear film dynamics of the respective species. The species differences, as well as regional mucin expression patterns, characterized in this study further define the biochemical composition of the ocular surface and may play an important role in tear film stability.
Clinical aspects and prognosis of corneal burns mainly depend on the agent responsible for the trauma. The most severe burns are caustic burns, which should be classified as burns caused by basic agents, associated with deep and prolonged injuries, and burns caused by acidic agents, associated with more superficial injuries. At the acute stage, caustic burns induce epithelial defects, corneal edema, and ischemic necrosis of the limbus, conjunctiva, iris and ciliary body. At the early stage, reepithelialization occurs and is often associated with corneal vascularization and stromal infiltrates, followed by corneal scar formation. At the chronic stage, the following complications are possible: corneal scars, limbal stem cell insufficiency, lachrymal insufficiency, irregular astigmatism, ocular surface fibrosis, cataract, glaucoma, decreased intraocular pressure, and ocular atrophy. The Ropper-Hall classification is based on the extent of limbal ischemia. Thermal burns induce epithelial defects at the acute stage, with the more severe forms giving the same complications as caustic burns. Radiation-related burns can be caused by ultraviolet radiations (acute epithelial keratitis, pterygium, droplet-like keratitis), microwaves, infrared radiations, ionizing radiations or, laser radiations. Electrical burns are often a result of torture and give corneal stroma opacification.
Jankov II, Mirko R.; Jovanovic, Vesna; Nikolic, Ljubisa; Lake, Jonathan C.; Kymionis, Georgos; Coskunseven, Efekan
Corneal collagen cross-linking (CXL) with riboflavin and ultraviolet-A (UVA) is a new technique of corneal tissue strengthening by using riboflavin as a photosensitizer and UVA to increase the formation of intra and interfibrillar covalent bonds by photosensitized oxidation. Keratocyte apoptosis in the anterior segment of the corneal stroma all the way down to a depth of about 300 microns has been described and a demarcation line between the treated and untreated cornea has been clearly shown. It is important to ensure that the cytotoxic threshold for the endothelium has not been exceeded by strictly respecting the minimal corneal thickness. Confocal microscopy studies show that repopulation of keratocytes is already visible 1 month after the treatment, reaching its pre-operative quantity and quality in terms of functional morphology within 6 months after the treatment. The major indication for the use of CXL is to inhibit the progression of corneal ectasias, such as keratoconus and pellucid marginal degeneration. CXL may also be effective in the treatment and prophylaxis of iatrogenic keratectasia, resulting from excessively aggressive photoablation. This treatment has also been used to treat infectious corneal ulcers with apparent favorable results. Combination with other treatments, such as intracorneal ring segment implantation, limited topography-guided photoablation and conductive keratoplasty have been used with different levels of success. PMID:20543933
Executive Summary Objective The purpose of this project was to determine the role of corneal implants in the management of corneal thinning disease conditions. An evidence-based review was conducted to determine the safety, effectiveness and durability of corneal implants for the management of corneal thinning disorders. The evolving directions of research in this area were also reviewed. Subject of the Evidence-Based Analysis The primary treatment objectives for corneal implants are to normalize corneal surface topography, improve contact lens tolerability, and restore visual acuity in order to delay or defer the need for corneal transplant. Implant placement is a minimally invasive procedure that is purported to be safe and effective. The procedure is also claimed to be adjustable, reversible, and both eyes can be treated at the same time. Further, implants do not limit the performance of subsequent surgical approaches or interfere with corneal transplant. The evidence for these claims is the focus of this review. The specific research questions for the evidence review were as follows: Safety Corneal Surface Topographic Effects: Effects on corneal surface remodelling Impact of these changes on subsequent interventions, particularly corneal transplantation (penetrating keratoplasty [PKP]) Visual Acuity Refractive Outcomes Visual Quality (Symptoms): such as contrast vision or decreased visual symptoms (halos, fluctuating vision) Contact lens tolerance Functional visual rehabilitation and quality of life Patient satisfaction: Disease Process: Impact on corneal thinning process Effect on delaying or deferring the need for corneal transplantation Clinical Need: Target Population and Condition Corneal ectasia (thinning) comprises a range of disorders involving either primary disease conditions such as keratoconus and pellucid marginal corneal degeneration or secondary iatrogenic conditions such as corneal thinning occurring after LASIK refractive surgery. The condition
Verstraelen, Jessica; Reichl, Stephan
Preclinical studies addressing the transcorneal absorption of ophthalmic drugs are mainly performed using ex vivo animal corneas and in vitro corneal cell culture models, leaving open the question of transferability to humans in an in vivo situation. While passive drug absorption through corneal tissue is well understood, little is known about the expression of transporter proteins and active drug transport in human and animal corneas as well as corneal cell culture models. Therefore, the aim of this study was to conduct an expression analysis of four multidrug resistance-associated proteins (MRP1, 2, 4 and 5) in various in vitro and ex vivo corneal models, leading to a better understanding of the comparability of different corneal models regarding drug absorption and transferability to humans. Two well-established in vitro human corneal models, the HCE-T epithelial model and the more organotypic Hemicornea construct, both of which are based on the SV40 immortalized human corneal epithelial cell line HCE-T, were analyzed, as were excised rabbit and porcine cornea. Specimens of abraded epithelia from human donor corneas were also tested. MRP mRNA expression was determined via reverse transcriptase polymerase chain reaction. Protein expression was examined using Western blot experiments and immunohistochemistry. The functional activity of the MRP efflux transporter was detected in transport assays using specific marker and inhibitor substances. The functional expression of all of the tested MRP transporters was detected in the HCE-T epithelial model. Hemicornea constructs displayed a similar expression pattern for MRP1, 4 and 5, whereas no MRP2 protein expression or activity was detected. However, excised animal corneas exhibited different expression profiles. In porcine cornea, no functional expression of MRP1, 2, or 5 was observed, and we failed to detect MRP4 expression in rabbit cornea. The results suggest that MRP1, 2, 4, and 5 are expressed in the human corneal
Yang, Yong-mei; Wu, Xin-yi; Du, Li-qun
To study the expression and location of connective tissue growth factor (CTGF) and transforming growth factor-beta(1) (TGF-beta(1)) protein and mRNA in rabbit cornea during the wound healing process. To assess the interaction between CTGF and TGF-beta(1), as well as the Smad signaling pathway involved. Twenty-six Albino white rabbits were used as experimental animals and randomly divided into 4 groups: (1) CONTROL GROUP: two rabbits. (2) Simple corneal injury group: a 3 mm diameter and 0.05 mm depth corneal tissue was excised by a trephine at the anterior central cornea as a corneal wound model in 12 rabbits. Two rabbits were randomly sacrificed at 2 h, 6 h, 1 d, 3 d, 7 d and 21 d after the trauma. (3) TGF-beta(1) antibodies treated group: 6 rabbits were injected with TGF-beta(1) antibodies (15.5 microg) subconjunctivally after corneal trephine. Two rabbits were randomly sacrificed at 3 d, 7 d and 21 d after the injection. (4) Smad4 antibodies treated group: 6 rabbits were injected with Smad4 antibodies (20 microg) subconjunctivally after corneal trephine. Two rabbits were randomly sacrificed at 3 d, 7 d and 21 d after the injection. Protein of CTGF, TGF-beta(1), and FN was assessed with immunohistochemistry. CTGF and type one collagen mRNA were measured in by in situ hybridization. (1) CTGF protein or mRNA did not exist in normal rabbit corneas, but TGF-beta(1) protein was expressed in normal rabbit cornea epithelium. (2) Cornea fibroblasts activated 6 h after the operation. Expression of CTGF, TGF-beta(1), FN protein and mRNA of CTGF and type one collagen were upregulated after cornea injury, and reached the highest level in 3 days. The expression was reduced to the basal level 21 days later. (3) Injection of TGF-beta(1) antibodies reduced the expression of CTGF, TGF-beta(1) and FN in the cornea stroma and down-regulated the expression of CTGF in corneal epithelial cells. (4) Injection of Smad4 antibodies inhibited the expression of TGF in the stroma but did not
Aldebasi, Yousef H.; Mohamed, Hala A.; Aly, Salah M.
Aim This study aimed to investigate the pathogenic effect of bacteria causing infectious keratitis among patients through experimental study conducted on rabbits’ eyes with the aid of histopathology as eye infection is a common disease in developing countries that may complicate to loss of vision. Methodology 100 swab samples were collected from human infected eyes, at Qassim region during 2012, for the isolation of Pseudomonas aeruginosa and Staphylococcus aureus. The isolated pathogenic bacteria were tested to various antibiotics using some selected antibiotics discs through agar-well diffusion method. Then, experimental study conducted on 27 rabbits. The rabbits were divided randomly into three equal groups, each containing 9 rabbits. Rabbits of group (1) served as control group (Negative Control) and their eyes were inoculated with the buffer only. Rabbits of group (2) were inoculated through eyes with the isolated Pseudomonas aeruginosa. Rabbits of group (3) were inoculated through eyes with the isolated Staphylococcus aureus. Results Out of 100 collected swab samples from human infected eyes, Pseudomonas aeruginosa and Staphylococcus aureus were isolated with a total percentage of 25.21% and 15.65%; respectively and used in this study. Both bacterial isolates were sensitive to Gentamicin and Cefuroxime. Clinically, experimentally infected rabbits by Pseudomonas aeruginosa, revealed varying degree corneal abrasions, corneal abscess and dense corneal opacity. Histopathologically, at 3rd day post-infection (PI), the cornea revealed polymorpho-nuclear cells infiltration with loss of the outer epithelial lining. At 7th day PI, neutrophils were seen in the stroma. At 15th day PI, proliferation of fibroblasts and new vascularisation were seen in the stroma. Clinically, rabbits experimentally infected with Staphylococcus aureus, revealed corneal ulcers and focal abscesses. Histopathologically, at 3rd and 7th day PI, the cornea revealed edema and infiltration of
Choi, Hyuk Jin; Kim, Mee Kum; Lee, Hyun Ju; Ko, Jung Hwa; Jeong, So Hee; Lee, Jae-Il; Oh, Byoung-Chol; Kang, Hee Jung; Wee, Won Ryang
PURPOSE. To solve the shortage of donor corneas, a decellularizing method based on hypertonic saline treatment was introduced, and a favorable outcome was observed in pig-to-rabbit lamellar corneal transplantation. This study was an investigation of the efficacy of pig-to-nonhuman primate lamellar corneal transplantation, using both decellularized and fresh porcine corneas to assess feasibility as a substitute for human corneas. METHODS. Nine Chinese rhesus macaques underwent lamellar corneal transplantation using both decellularized (n = 5) and fresh (n = 4) porcine corneas. Clinically acceptable graft size (7.5 mm in diameter) and minimal immunosuppression based on topical and systemic corticosteroids were applied. Rejection signs, histology of porcine grafts, and serial changes in recipients' blood profile, including memory T-cell subset, anti-α-Gal and donor pig-specific antibodies, and complement were evaluated. Changes in aqueous complement concentration were also assessed at 4 weeks after transplantation. RESULTS. Of the decellularized porcine lamellar grafts, 80% remained transparent for more than 6 months, whereas half of the fresh porcine lamellar grafts developed chronic rejection. Rejected grafts showed extensive cellular infiltration, predominantly CD8(+) T lymphocytes and macrophages. Immunologic profiles of the recipients with rejected grafts showed a significant increase in the concentration of aqueous complement, an enhancement of memory T cells, and an abrupt increase in donor pig-specific antibodies. CONCLUSIONS. The findings suggested that decellularized porcine cornea could be a promising substitute for human corneal allograft. Fresh porcine cornea may be a feasible option for a substitute if combined with more potent immunosuppression or if obtained from transgenic pigs with complement-regulatory proteins.
Myrna, Kathern E.; Mendonsa, Rima; Russell, Paul; Pot, Simon A.; Liliensiek, Sara J.; Jester, James V.; Nealey, Paul F.; Brown, Donald
Purpose. The transition of corneal fibroblasts to the myofibroblast phenotype is known to be important in wound healing. The purpose of this study was to determine the effect of topographic cues on TGFβ-induced myofibroblast transformation of corneal cells. Methods. Rabbit corneal fibroblasts were cultured on nanopatterned surfaces having topographic features of varying sizes. Cells were cultured in media containing TGFβ at concentrations ranging from 0 to 10 ng/mL. RNA and protein were collected from cells cultured on topographically patterned and planar substrates and analyzed for the myofibroblast marker α-smooth muscle actin (αSMA) and Smad7 expression by quantitative real time PCR. Western blot and immunocytochemistry analysis for αSMA were also performed. Results. Cells grown on patterned surfaces demonstrated significantly reduced levels of αSMA (P < 0.002) compared with planar surfaces when exposed to TGFβ; the greatest reduction was seen on the 1400 nm surface. Smad7 mRNA expression was significantly greater on all patterned surfaces exposed to TGFβ (P < 0.002), whereas cells grown on planar surfaces showed equal or reduced levels of Smad7. Western blot analysis and αSMA immunocytochemical staining demonstrated reduced transition to the myofibroblast phenotype on the 1400 nm surface when compared with cells on a planar surface. Conclusions. These data demonstrate that nanoscale topographic features modulate TGFβ-induced myofibroblast differentiation and αSMA expression, possibly through upregulation of Smad7. It is therefore proposed that in the wound environment, native nanotopographic cues assist in stabilizing the keratocyte/fibroblast phenotype while pathologic microenvironmental alterations may be permissive for increased myofibroblast differentiation and the development of fibrosis and corneal haze. PMID:22232431
Myrna, Kathern E; Mendonsa, Rima; Russell, Paul; Pot, Simon A; Liliensiek, Sara J; Jester, James V; Nealey, Paul F; Brown, Donald; Murphy, Christopher J
The transition of corneal fibroblasts to the myofibroblast phenotype is known to be important in wound healing. The purpose of this study was to determine the effect of topographic cues on TGFβ-induced myofibroblast transformation of corneal cells. Rabbit corneal fibroblasts were cultured on nanopatterned surfaces having topographic features of varying sizes. Cells were cultured in media containing TGFβ at concentrations ranging from 0 to 10 ng/mL. RNA and protein were collected from cells cultured on topographically patterned and planar substrates and analyzed for the myofibroblast marker α-smooth muscle actin (αSMA) and Smad7 expression by quantitative real time PCR. Western blot and immunocytochemistry analysis for αSMA were also performed. Cells grown on patterned surfaces demonstrated significantly reduced levels of αSMA (P < 0.002) compared with planar surfaces when exposed to TGFβ; the greatest reduction was seen on the 1400 nm surface. Smad7 mRNA expression was significantly greater on all patterned surfaces exposed to TGFβ (P < 0.002), whereas cells grown on planar surfaces showed equal or reduced levels of Smad7. Western blot analysis and αSMA immunocytochemical staining demonstrated reduced transition to the myofibroblast phenotype on the 1400 nm surface when compared with cells on a planar surface. These data demonstrate that nanoscale topographic features modulate TGFβ-induced myofibroblast differentiation and αSMA expression, possibly through upregulation of Smad7. It is therefore proposed that in the wound environment, native nanotopographic cues assist in stabilizing the keratocyte/fibroblast phenotype while pathologic microenvironmental alterations may be permissive for increased myofibroblast differentiation and the development of fibrosis and corneal haze.
Reddy, Jagadesh C; Rapuano, Christopher J; Nagra, Parveen K; Hammersmith, Kristin M
To evaluate and compare the visual outcomes and recurrence patterns of corneal stromal dystrophies after excimer laser phototherapeutic keratectomy (PTK) in eyes with and without a corneal graft. Retrospective, comparative case series. setting: Cornea Service, Wills Eye Institute, Philadelphia Pennsylvania. study population: The patients were divided into 2 groups. Group 1 comprised patients with no graft who underwent PTK (22 eyes of 15 patients), and group 2 comprised patients who underwent PTK over a previous full-thickness graft (18 eyes of 14 patients). intervention: All patients underwent PTK for decreased vision, symptoms of recurrent erosions, or both. main outcome measures: Visual outcomes and recurrence patterns of corneal stromal dystrophies. Preoperative and postoperative best-corrected visual acuities were 0.46 ± 0.25 and 0.51 ± 0.27 (P = .56), respectively, in group 1 and 0.16 ± 0.13 and 0.21 ± 0.18 (P = .25), respectively, in group 2. Mean preoperative spherical equivalent was 1.54 ± 2.59 diopters (D) and -5.10 ± 5.81 D (P = .01) in groups 1 and 2, respectively, and mean postoperative spherical equivalent was 0.44 ± 1.8 D and -1.8 ± 4.25 D (P = .19) in groups 1 and 2, respectively. There was no statistically significant difference in the efficacy (P = .73) and safety (P = .62) indices between the 2 groups. In group 1, mild recurrence was seen in 7 eyes (32%) and significant recurrence was seen in 4 eyes (18%) at a mean of 32 and 47 months after PTK, respectively. In group 2, mild recurrence was seen in 5 eyes (28%) and significant recurrence was seen in 5 eyes (28%) at a mean of 36 and 50 months after PTK, respectively. PTK improved central corneal clarity, alleviated symptoms resulting from recurrent erosions, and improved visual acuity in both groups. Copyright © 2013 Elsevier Inc. All rights reserved.
Röck, Daniel; Wude, Johanna; Yoeruek, Efdal; Bartz-Schmidt, Karl Ulrich; Röck, Tobias
BACKGROUND This study aimed to investigate factors limiting corneal donation at the University Hospital Tübingen. MATERIAL AND METHODS We retrospectively studied all hospital deaths from January 2012 to December 2015, considering each deceased patient as a potential corneal donor. During this period an ophthalmic resident managed corneal donor procurement on a full-time basis. Various factors limiting corneal donation were examined. RESULTS Among the 3412 deaths, 2937 (86.1%) displayed nonfulfillment of corneal donation. Consent for corneal donation was obtained in 475 cases (13.9%). The mean annual corneal donation rate was 13.9 donors per 100 deaths (range: 11.2-17.8). The leading causes of nonfulfillment of corneal donations were refusal to donate (49.8%, 1698 cases) and medical contraindications (23.6%, 805 cases). After next-of-kin interview of 2173 potential donors (109 potential donors were excluded because of logistical problems), willingness to participate in corneal donation was present in 475 cases (21.9%), whereas in 1698 cases (78.1%) corneal donation was refused. CONCLUSIONS Our study showed refusal to donate is the most important factor limiting corneal donation. It seems that increasing the knowledge of people about corneal donation through public education and media are necessary to address the corneal shortage.
Torricelli, Andre A. M.; Santhanam, Abirami; Wu, Jiahui; Singh, Vivek; Wilson, Steven E.
The corneal wound healing response, including the development of stromal opacity in some eyes, is a process that often leads to scarring that occurs after injury, surgery or infection to the cornea. Immediately after epithelial and stromal injury, a complex sequence of processes contributes to wound repair and regeneration of normal corneal structure and function. In some corneas, however, often depending on the type and extent of injury, the response may also lead to the development of mature vimentin+ α-smooth muscle actin+ desmin+ myofibroblasts. Myofibroblasts are specialized fibroblastic cells generated in the cornea from keratocyte-derived or bone marrow-derived precursor cells. The disorganized extracellular matrix components secreted by myofibroblasts, in addition to decreased expression of corneal crystallins in these cells, are central biological processes that result in corneal stromal fibrosis associated with opacity or “haze”. Several factors are associated with myofibroblast generation and haze development after PRK surgery in rabbits, a reproducible model of scarring, including the amount of tissue ablated, which may relate to the extent of keratocyte apoptosis in the early response to injury, irregularity of stromal surface after surgery, and changes on corneal stromal proteoglycans, but normal regeneration of the epithelial basement membrane (EBM) appears to be a critical factor determining whether a cornea heals with relative transparency or vision-limiting stromal opacity. Structural and functional abnormalities of the regenerated EBM facilitate prolonged entry of epithelium-derived growth factors such as transforming growth factor β (TGF-β) and platelet-derived growth factor (PDGF) into the stroma that both drive development of mature myofibroblasts from precursor cells and lead to persistence of the cells in the anterior stroma. A major discovery that has contributed to our understanding of haze development is that keratocytes and
Camps, Vicente J; Piñero, David P; Caravaca-Arens, Esteban; de Fez, Dolores; Pérez-Cambrodí, Rafael J; Artola, Alberto
The aim of this study was to obtain the exact value of the keratometric index (nkexact) and to clinically validate a variable keratometric index (nkadj) that minimizes this error. The nkexact value was determined by obtaining differences (ΔPc) between keratometric corneal power (Pk) and Gaussian corneal power ((Equation is included in full-text article.)) equal to 0. The nkexact was defined as the value associated with an equivalent difference in the magnitude of ΔPc for extreme values of posterior corneal radius (r2c) for each anterior corneal radius value (r1c). This nkadj was considered for the calculation of the adjusted corneal power (Pkadj). Values of r1c ∈ (4.2, 8.5) mm and r2c ∈ (3.1, 8.2) mm were considered. Differences of True Net Power with (Equation is included in full-text article.), Pkadj, and Pk(1.3375) were calculated in a clinical sample of 44 eyes with keratoconus. nkexact ranged from 1.3153 to 1.3396 and nkadj from 1.3190 to 1.3339 depending on the eye model analyzed. All the nkadj values adjusted perfectly to 8 linear algorithms. Differences between Pkadj and (Equation is included in full-text article.)did not exceed ±0.7 D (Diopter). Clinically, nk = 1.3375 was not valid in any case. Pkadj and True Net Power and Pk(1.3375) and Pkadj were statistically different (P < 0.01), whereas no differences were found between (Equation is included in full-text article.)and Pkadj (P > 0.01). The use of a single value of nk for the calculation of the total corneal power in keratoconus has been shown to be imprecise, leading to inaccuracies in the detection and classification of this corneal condition. Furthermore, our study shows the relevance of corneal thickness in corneal power calculations in keratoconus.
Mashima, Y; Kawai, M; Yamada, M
Aims: To evaluate corneal electrolysis as a treatment for recurrent diffuse corneal opacities at the host-graft interface of the stroma or at the subepithelial region in two types of granular corneal dystrophy (GCD). Methods: Recurrence developed at the host-graft interface of the stroma after lamellar keratoplasty in a patient with Avellino corneal dystrophy (ACD). At surgery, the deep aspect of the graft in this patient was partially separated from host tissue to expose the deposits, with one third of the host-graft junction left intact. The graft was everted, and electrolysis was applied directly to remove the deposits attached to both surfaces of the host and the graft. Then the graft was returned to its place and sutured. In two patients with homozygous ACD and one patient with the superficial variant of GCD, diffuse subepithelial opacities developed following penetrating keratoplasty. Electrolysis was applied directly to the corneal surface. Results: Deposits at the host-graft interface of the stroma and in the subepithelial region disappeared following treatment, and vision recovered in all patients. Conclusions: This method is a simple, easy, and inexpensive way to remove deposits that recur after lamellar or penetrating keratoplasty. PMID:11864880
Letafatnejad, Mojgan; Beheshtnejad, Amir Hooshang; Ghaffary, Seyed Reza; Hassanpoor, Narges; Yaseri, Mehdi
Purpose. To evaluate the difference in biomechanical properties between contact lens induced corneal warpage and normal and keratoconic eyes. Method. Prospective observational case control study, where 94 eyes of 47 warpage suspicious and 46 eyes of 23 keratoconic patients were included. Warpage suspected cases were followed until a definite diagnosis was made (warpage, normal, or keratoconus). Results. 44 eyes of 22 patients had contact lens related corneal warpage. 46 eyes of 23 people were diagnosed as nonwarpage normal eyes. 46 eyes of 23 known keratoconus patients were included for comparison. The mean age of the participants was 23.8 ± 3.8 years, and 66.2% of the subjects were female. The demographic and refractive data were not different between warpage and normal groups but were different in the keratoconus group. The biomechanical properties (corneal hysteresis or CH and corneal resistance factor or CRF) were different with the highest value in the warpage group followed by normal and keratoconus groups. CRF was 10.08 ± 1.75, 9.23 ± 1.22, and 7.38 ± 2.14 and CH was 10.21 ± 1.57, 9.59 ± 1.21, and 8.69 ± 2.34 in the warpage, normal, and keratoconus groups, respectively. Conclusion. Corneal biomechanics may be different in people who develop contact lens induced warpage. PMID:27688908
Navaratnam, Jesintha; Utheim, Tor P.; Rajasekhar, Vinagolu K.; Shahdadfar, Aboulghassem
Corneal endothelium is a single layer of specialized cells that lines the posterior surface of cornea and maintains corneal hydration and corneal transparency essential for vision. Currently, transplantation is the only therapeutic option for diseases affecting the corneal endothelium. Transplantation of corneal endothelium, called endothelial keratoplasty, is widely used for corneal endothelial diseases. However, corneal transplantation is limited by global donor shortage. Therefore, there is a need to overcome the deficiency of sufficient donor corneal tissue. New approaches are being explored to engineer corneal tissues such that sufficient amount of corneal endothelium becomes available to offset the present shortage of functional cornea. Although human corneal endothelial cells have limited proliferative capacity in vivo, several laboratories have been successful in in vitro expansion of human corneal endothelial cells. Here we provide a comprehensive analysis of different substrates employed for in vitro cultivation of human corneal endothelial cells. Advances and emerging challenges with ex vivo cultured corneal endothelial layer for the ultimate goal of therapeutic replacement of dysfunctional corneal endothelium in humans with functional corneal endothelium are also presented. PMID:26378588
Schulz, Simon; Beck, David; Laird, Dougal; Steinberg, Thorsten; Tomakidi, Pascal; Reinhard, Thomas; Eberwein, Philipp
To achieve durable recognition as a promising animal experiment-abandoning tool in ophthalmology, in vitro engineered tissue equivalents of the human cornea should exhibit proper morphogenesis. Regarding this issue, we were seeking for the natural cell microenvironment fulfilling the minimum requirements to allow human corneal keratinocytes to develop a balanced epithelial morphology with regular spatial appearance of tissue homeostatic biomarkers. Hence, we established cocultures of 3D cell-based collagen scaffolds comprising immortalized corneal keratinocytes combined with a gradual cornea-derived in vivo-like cell microenvironment, together with immortalized stromal fibroblasts alone (nonholistic) or fibroblasts and immortalized endothelial cells (holistic). With matched non-holistic microenvironments revealing mostly flattened cells and putative apical cell ablation foci at day 6, and 9 in HE stains, holistic counterparts yielded proper epithelial stratification with cell flattening restricted to apical layers. Concordantly, RT(2)-PCR showed a tremendous increase in gene expression for progressive and terminal biomarkers of corneal keratinocyte differentiation, cytokeratin (CK) 12, and filaggrin (FIL), in response to nonholistic environments, while involucrin (INV) was moderately but significantly upregulated. Although visible, this increase was moderate in corneal keratinocytes with a holistic environment. On the protein level, indirect immunofluorescence revealed that only epithelia of holistic environments showed diminishment in CK19, counteracted by CK12 rising over time. This time-dependent progression in differentiation coincided with declined proliferation and tissue-regular focus of differentiation biomarkers inv and fil to suprabasal and apical cell layers. Our novel findings suggest the interplay of native tissue forming cell entities, important for balanced corneal epithelial morphogenesis. In addition, they provide evidence for a holistic cell
Alsmman Hassan, Alahmady Hamad; Abd Elhaliem Soliman, Nesreen Gamal-Eldeen
Background. Many patients with corneal opacity or complicated cataract in blind eye ask for cosmoses. In this study we tried to investigate the staining of corneas of male rabbits by Rotring China painting ink and to study the histological changes. Method. 10 eyes of 10 male Baladi Egyptian rabbits were injected (0.1 mL) intrastromally in the cornea by the use of China painting ink (Rotring Tinta China) through insulin syringe (27-gauge needle) by single injection; clinical follow-up is for 6 months and lastly the rabbits were scarified and the stained eyes were enucleated for histological analysis. Results. Clinically the stain was stable in color and distribution in corneas with no major complications. Histological results of the stained rabbit corneas showed blackish pigmentation in the corneal stroma without any inflammatory cellular infiltration. Some fibroblast cells had pigment granules in their cytoplasm in the adjacent layers. Conclusion. Corneal staining by China painting ink is effective and safe in staining of male rabbits cornea; however further study in human corneas with longer follow-up period is advisable. PMID:27195146
Gürlü, Vuslat Pelitli; Erda, Nazan
To report the acute management and clinical findings of a case of corneal bee sting and to report the outcome of corneal endothelial cell analysis 1 year after trauma. Clinical findings, anterior segment photographs, corneal endothelial images, and medical treatment of a case of right corneal bee sting are presented. Right and left central corneal endothelial cell analysis was performed by noncontact specular microscopy. The stinger was removed from the cornea. Systemic, subconjunctival, and topical steroids and systemic and topical antibiotics were given. One year later, a corneal scar and anterior capsular opacity of the lens in the right eye were shown by slit-lamp examination. Endothelial cell analysis determined that the endothelial cell density of the right eye was substantially decreased compared with the left eye. Corneal infiltration gradually decreased, presumably because of the systemic, topical, and subconjunctival steroids. Late complications observed in this case included a substantial decrease in cornea endothelial cell density, a corneal scar, and anterior capsular opacity.
Park, Young-Woo; Kang, Byung-Jae; Lim, Jae Hyun; Ahn, Jung-Mo; Lim, Hyun Sook
A 13-year-old castrated male Yorkshire terrier developed a corneal ulcer 2 weeks after intracapsular lens extraction (ICLE) in the right eye. The corneal ulcer was treated with levofloxacin eye drops. A plaque with a white luster developed in the central cornea 2 weeks after treatment with levofloxacin eye drops. The corneal plaque was surgically removed under inhalant anesthesia. The corneal plaque displayed antimicrobial activity against Escherichia coli. Furthermore, levofloxacin content in the plaque was confirmed by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight (MALDI-TOF/TOF) mass spectrometry (MS). The corneal ulcer completely resolved 2 weeks after the surgical removal of the corneal lesion and replacement of levofloxacin eye drops with tobramycin eye drops. Although the topical use of levofloxacin is unlikely to lead to corneal chemical deposits due to the high water solubility of the drug compared to other topical fluoroquinolones, this patient developed corneal plaque of the antibiotic drop.
Sharma, Charu; Velpandian, Thirumurthy; Biswas, Nihar Ranjan; Nayak, Niranjan; Vajpayee, Rasik Bihari; Ghose, Supriyo
This study was undertaken to determine in vivo permeability coefficients for fluoroquinolones and to assess its correlation with the permeability derived using reported models in the literature. Further, the aim was to develop novel QSPR model to predict corneal permeability for fluoroquinolones and test its suitability on other training sets. The in vivo permeability coefficient was determined using cassette dosing (N-in-One) approach for nine fluoroquinolones (norfloxacin, ciprofloxacin, lomefloxacin, ofloxacin, levofloxacin, sparfloxacin, pefloxacin, gatifloxacin, and moxifloxacin) in rabbits. The correlation between corneal permeability derived using in vivo studies with that derived from reported models was determined. Novel QSPR-based model was developed using in vivo corneal permeability along with other molecular descriptors. The suitability of developed model was tested on β-blockers (n = 15). The model showed better prediction of corneal permeability for fluoroquinolones (r2 > 0.9) as well as β-blockers (r2 > 0.6). The newly developed QSPR model based upon in vivo generated data was found suitable to predict corneal permeability for fluoroquinolones as well as other sets of compounds. PMID:21403901
Fini, M. E.; Parks, W. C.; Rinehart, W. B.; Girard, M. T.; Matsubara, M.; Cook, J. R.; West-Mays, J. A.; Sadow, P. M.; Burgeson, R. E.; Jeffrey, J. J.; Raizman, M. B.; Krueger, R. R.; Zieske, J. D.
Delayed re-epithelialization of the cornea after injury usually precedes stromal ulceration. Previous findings using a rat thermal injury model suggested that re-epithelialization is impeded by products of resident corneal cells, which destroy adhesive structures at the basement membrane zone. In this study, we provide additional evidence for this concept. Failure to re-epithelialize was found to correlate with an increase in the amounts of gelatinolytic matrix metalloproteinases present in the rat cornea. One of these gelatinases, gelatinase B, is synthesized by the resident corneal cells, and inhibitions of its synthesis correlated with inhibition of basement membrane dissolution. The matrix metalloproteinases collagenase and stromelysin are also synthesized by resident corneal cells in thermally injured corneas of rabbits, but the timing of bulk enzyme synthesis correlated more closely with deposition of repair tissue in the stroma than with failure to re-epithelialize. Nevertheless, in human corneas with repair defects, gelatinase B and collagenase are synthesized by cells in the basal layer of the epithelium directly adjacent to the basement membrane, suggesting that both could participate in dissolution of this structure. Importantly, treatment of thermally injured corneas with a synthetic inhibitor of matrix metalloproteinases significantly improved basement membrane integrity. These data support the concept that over-expression of matrix metalloproteinases by resident corneal cells impedes re-epithelialization after some types of corneal injury. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 8 PMID:8863676
Yusof, Alia Md; Abd Ghafar, Norzana; Kamarudin, Taty Anna; Hui, Chua Kien; Yusof, Yasmin Anum Mohd
This study aimed to evaluate the effects of Gelam honey on corneal keratocytes proliferative capacity and phenotypic characterization via MTT assay, gene expression and immunocytochemistry. Corneal keratocytes from New Zealand white rabbits were cultured in basal medium (BM) and serum enriched medium (BMS). Serial dilutions of Gelam honey (GH) were added to both media and cells were cultured until passage 1. MTT assay was performed on corneal keratocytes in both media to ascertain the optimal dose of GH that produced maximum proliferation. Gelam honey at the concentration of 0.0015% in both media showed the highest proliferative capacity with no morphological changes compared to their respective controls. The gene expression of aldehyde dehydrogenase (ALDH), a marker for quiescent keratocytes and vimentin, a marker for fibroblast, were higher in the GH enriched groups. The alpha smooth muscle actin (α-SMA) expression, marker for myofibroblast, was lower in GH treated groups compared to the controls. Immunocytochemistry results were in accordance to the gene expression analyses. Gelam honey at a concentration of 0.0015% promotes ex vivo corneal keratocytes proliferation while retaining desirable phenotype expression. The results serve as a basis for the development of Gelam honey as a potential natural product in promoting corneal wound healing.
Ayaki, Masahiko; Shimada, Kazuo; Yaguchi, Shigeo; Koide, Ryohei; Iwasawa, Atsuo
We investigated the corneal toxicity of ortho-phthalaldehyde (Cidex OPA, Johnson and Johnson K.K.) and its predecessor glutaraldehyde (Cidex, Johnson and Johnson K.K.). We made primary cultures of porcine and human corneal endothelial cells. Commercially available cell lines were also used including human, bovine, and rabbit corneal epithelium and human conjunctival cells. Following incubation for two days, cell survival was measured using a WST-1 assay for endothelia and a MTT assay for the other cells. Test solutions included 2.25% and 3.5% glutaraldehyde and 0.55% ortho-phthalaldehyde. Cell survival was presented as a percentage of the control value. ortho-phthalaldehyde displayed less toxicity than glutaraldehyde for all cell types tested. As expected 3.5% glutaraldehyde was slightly more toxic than 2.25% glutaraldehyde. When primary human corneal endothelial cultures were exposed to ortho-phthalaldehyde, the survival rates were 88% for 100-fold dilutions and 95% for 500-fold dilutions. The survival rates for all cells tested were greater than 90% when dilutions of 1000-fold or more were used. In conclusion, the corneal toxicity of glutaraldehyde and ortho-phthalaldehyde appears to be within safe levels following washing procedures and therefore the use of these disinfectants may be suitable for selected ophthalmic surgical instruments in urgent or under-equipped circumstances.
Matalia, Jyoti; Francis, Mathew; Tejwani, Sushma; Dudeja, Gagan; Rajappa, Neha; Sinha Roy, Abhijit
To assess the correlation of age and myopia with corneal and extraocular tissue stiffness derived from air-puff applanation using a composite viscoelastic model. This retrospective, cross-sectional study evaluated 155 normal eyes (age range: 5 to 50 years) measured on Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany). Manifest refraction spherical equivalent was also analyzed. A linear viscoelastic model that segregated corneal and extraocular tissue stiffness from the applanation deformation waveform was implemented. Corvis ST measured the total deformation (deformation amplitude waveform), which was simply the sum of corneal and extraocular tissue deformation. Age- and myopia-based multivariate analyses of variance between deformation parameters were performed after adjusting for intraocular pressure and central corneal thickness. Corvis ST corneal hysteresis was also calculated from the corneal deformation waveform. All myopia and age groups were matched for intraocular pressure and central corneal thickness. Extraocular tissue stiffness significantly increased with age (P = .03). Some other extraocular tissue deformation parameters also correlated with age, indicating age-related stiffening (P < .05). Corneal and extraocular tissue stiffness decreased with increasing myopia, but the trend was not significant (P = .10). Corvis ST corneal hysteresis increased with increasing age (P = .01) but not with increasing myopia (P = .61). Extraocular deformation parameters indicated stiffening of the extraocular tissues with age. Corneal deformation parameters were unaffected by age and myopia. Further studies with larger sample sizes are needed to clearly understand the effect of myopia on corneal and extraocular tissue stiffness. [J Refract Surg. 2016;32(7):486-493.]. Copyright 2016, SLACK Incorporated.
Bourges, J-L; Hubschman, J-P; Burt, B; Culjat, M; Schwartz, S D
Robotic ocular microsurgery including corneal suturing has been proven to be feasible in porcine eyes. To determine whether or not bimanual teleoperated robotic penetrating keratoplasty (PK) can be performed in porcine and human eyes. Three arms of the da Vinci surgical robot were loaded with a dual-channel video and two, 360 degrees -rotating, 8 mm, wrested-end effector instruments and placed over porcine eyes or over a human cadaver head. The surgeon remotely performed mechanical trephination, cardinal sutures, continuous 10.0 nylon sutures and suture adjustments on both eyes. The procedures were documented with still and video photography. Using the da Vinci robot, penetrating keratoplasty procedures were successfully performed on both porcine eyes and human eyes in natural anatomical conditions. The precise placement of continuous sutures was facilitated by the wrested-end forceps. Orbital rims and nose did not limit surgical motions. Teleoperated robotic penetrating keratoplasty is technically feasible in humans. Further studies are pending to implement the procedure with femtosecond laser and other automated steps.
Halberstadt, M; Athmann, S; Hagenah, M
Different methods of corneal cryopreservation have been introduced, those employing intracellular cryoprotectants such as Me2SO or glycerol being the most widely favored. We investigated the influence of several freeze-thaw trauma variables on the survival of porcine endothelial monolayers when employing the extracellular cryoprotective agent dextran. We first examined the effects of various dextran concentrations and then, having ascertained the optimal concentration, further investigated the influence of fetal calf serum (FCS) concentration in the cryopreservation medium, the cooling rate, the thawing temperature, and the length of the preincubation in the freezing medium prior to cryopreservation. The numerical densities of endothelial cells were determined at dissection in hypoosmotic balanced salt solution and after organ culture by staining with alizarin red S and trypan blue. Morphological evaluation was not performed directly after thawing but after a subsequent organ culture at 37 degrees C to detect latent cell damage after freeze-thaw trauma. Our data revealed that corneas cryopreserved in minimal essential medium containing 10% dextran but lacking FCS, preincubated for 3 h, frozen at a cooling rate of 1 degrees C/min, and thawed at 37 degrees C incurred the lowest cell losses (22.4%, SD +/- 3.8). We conclude that dextran is an effective cryoprotectant for freezing of porcine corneas. However, variations between species in the results of cryopreservation require further investigation of an in vivo animal model and studies with human corneas before its clinical use can be recommended.
Piñero, David P; Alcón, Natividad
Biomechanics is often defined as 'mechanics applied to biology'. Due to the variety and complexity of the behaviour of biological structures and materials, biomechanics is better defined as the development, extension and application of mechanics for a better understanding of physiology and physiopathology and consequently for a better diagnosis and treatment of disease and injury. Different methods for the characterisation of corneal biomechanics are reviewed in detail, including those that are currently commercially available (Ocular Response Analyzer and CorVis ST). The clinical applicability of the parameters provided by these devices are discussed, especially in the fields of glaucoma, detection of ectatic disorders and orthokeratology. Likewise, other methods are also reviewed, such as Brillouin microscopy or dynamic optical coherence tomography and others with potential application to clinical practice but not validated for in vivo measurements, such as ultrasonic elastography. Advantages and disadvantages of all these techniques are described. Finally, the concept of biomechanical modelling is revised as well as the requirements for developing biomechanical models, with special emphasis on finite element modelling. © 2014 The Authors. Clinical and Experimental Optometry © 2014 Optometry Australia.
Alhayek, Adel; Lu, Pei-Rong
Keratoconus is a condition characterized by biomechanical instability of the cornea, presenting in a progressive, asymmetric and bilateral way. Corneal collagen crosslinking (CXL) with riboflavin and Ultraviolet-A (UVA) is a new technique of corneal tissue strengthening that combines the use of riboflavin as a photo sensitizer and UVA irradiation. Studies showed that CXL was effective in halting the progression of keratoconus over a period of up to four years. The published studies also revealed a reduction of max K readings by more than 2 D, while the postoperative spherical equivalent (SEQ) was reduced by an average of more than 1 D and refractive cylinder decreased by about 1 D. The major indication for the use of CXL is to inhibit the progression of corneal ecstasies, such as keratoconus and pellucid marginal degeneration. CXL may also be effective in the treatment and prophylaxis of iatrogenic keratectasia, resulting from excessively aggressive photo ablation. This treatment has been used to treat infectious corneal ulcers with apparent favorable results. Most recent studies demonstrate the beneficial impact of CXL for iatrogenic ecstasies, pellucid marginal degeneration, infectious keratitis, bullous keratopathy and ulcerative keratitis. Several long-term and short-term complications of CXL have been studied and documented. The possibility of a secondary infection after the procedure exists because the patient is subject to epithelial debridement and the application of a soft contact lens. Formation of temporary corneal haze, permanent scars, endothelial damage, treatment failure, sterile infiltrates, bullous keratopathy and herpes reactivation are the other reported complications of this procedure. PMID:25938065
Shiloh, Roni; Munitz, Hanan; Portuguese, Shirley; Gross-Isseroff, Ruth; Sigler, Mayanit; Bodinger, Liron; Katz, Nachum; Stryjer, Rafael; Hermesh, Haggai; Weizman, Abraham
Most data imply that dopaminergic transmission is essential for proper hypothalamic-mediated core temperature regulation. Altered central dopaminergic transmission is suggested to be involved in the pathophysiology of schizophrenia. Thus, hypothetically, schizophrenia patients might be at increased risk of developing thermoregulatory dysregulation manifested by alterations in core temperature, as well as in peripheral tissue, the temperature of which has been shown to correlate with core temperature (e.g. cornea). Previous small pilot studies of ours showed that schizophrenia patients may exhibit corneal temperature abnormalities. Hence, we assessed corneal temperature in a controlled sample of drug-free ( n =11) and medicated ( n =28) schizophrenia patients compared to healthy comparison subjects ( n =9), using a FLIR thermal imaging camera. Drug-free schizophrenia patients exhibited significantly higher corneal temperature compared to healthy subjects, typical antipsychotic drug (APD)-treated patients ( n =16) and atypical APD-treated patients ( n =12) (37.08+/-1.46 degrees C vs. 33.37+/-2.51 degrees C, 31.08+/-1.43 degrees C and 31.67+/-0.44 degrees C respectively, p <0.0001; p <0.001 vs. each group separately). The healthy comparison subjects and the atypical APD-treated patients exhibited comparable corneal temperatures and these two groups exhibited higher corneal temperatures compared to the typical APD-treated patients ( p <0.01 and p =0.051 respectively). In conclusion, this study indicates that drug-free schizophrenia patients exhibit substantially higher corneal temperature compared to healthy comparison subjects or medicated patients, and that APDs may decrease corneal temperature either to normal (atypical APD) or to subnormal (typical APD) values. The relevance of these phenomena to the pathophysiology of schizophrenia, the biological mechanism underlying drug-induced corneal temperature alterations, the possible role of temperature-lowering drugs
Chai, Dongyul; Gaster, Ronald N.; Roizenblatt, Roberto; Juhasz, Tibor; Brown, Donald J.
Purpose. Corneal collagen cross-linking (CXL) by the use of riboflavin and ultraviolet-A light (UVA) is a promising and novel treatment for keratoconus and other ectatic disorders. Since CXL results in enhanced corneal stiffness, this study tested the hypothesis that CXL-induced stiffening would be proportional to the collagen autofluorescence intensity measured with nonlinear optical (NLO) microscopy. Methods. Rabbit eyes (n = 50) were separated into five groups including: (1) epithelium intact; (2) epithelium removed; (3) epithelium removed and soaked in riboflavin, (4) epithelium removed and soaked in riboflavin, with 15 minutes of UVA exposure; and (5) epithelium removed and soaked in riboflavin, with 30 minutes of UVA exposure. Corneal stiffness was quantified by measuring the force required to displace the cornea 500 μm. Corneas were then fixed in paraformaldehyde and sectioned, and the collagen autofluorescence over the 400- to 450-nm spectrum was recorded. Results. There was no significant difference in corneal stiffness among the three control groups. Corneal stiffness was significantly and dose dependently increased after UVA (P < 0.0005). Autofluorescence was detected only within the anterior stroma of the UVA-treated groups, with no significant difference in the depth of autofluorescence between different UVA exposure levels. The signal intensity was also significantly increased with longer UVA exposure (P < 0.001). Comparing corneal stiffness with autofluorescence intensity revealed a significant correlation between these values (R2 = 0.654; P < 0.0001). Conclusions. The results of this study indicate a significant correlation between corneal stiffening and the intensity of collagen autofluorescence after CXL. This finding suggests that the efficacy of CXL in patients could be monitored by assessing collagen autofluorescence. PMID:21508101
Lu, Ying; Fukuda, Ken; Li, Qin; Kumagai, Naoki; Nishida, Teruo
The proinflammatory cytokine interleukin (IL)-1 is implicated in corneal ulceration. The role of nuclear factor (NF)-kappaB in the IL-1-induced degradation of collagen by corneal fibroblasts that underlies corneal ulceration was investigated. Rabbit corneal fibroblasts were cultured in three-dimensional gels of type I collagen with or without IL-1 and sulfasalazine, an inhibitor of NF-kappaB activation. Collagen degradation was assessed from the amount of hydroxyproline generated by acid-heat hydrolysis of culture supernatants. The release of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) into culture supernatants was examined by immunoblot analysis and gelatin zymography, and the cellular abundance of MMP and TIMP mRNAs was determined by reverse transcription and real-time polymerase chain reaction analysis. The phosphorylation and degradation of the NF-kappaB-inhibitory protein IkappaB-alpha were examined by immunoblot analysis. The subcellular localization and DNA binding activity of the p65 subunit of NF-kappaB were evaluated by immunofluorescence analysis and with a colorimetric assay, respectively. The transactivation activity of NF-kappaB was assessed with a reporter gene assay. Sulfasalazine inhibited IL-1-induced collagen degradation by corneal fibroblasts in a concentration-dependent manner. It also inhibited the stimulatory effects of IL-1 on the synthesis or activation of various MMPs in a concentration-dependent manner. IL-1 induced the phosphorylation and degradation of IkappaB-alpha, the nuclear translocation and up-regulation of the DNA binding activity of the p65 subunit of NF-kappaB, and the activation of NF-kappaB in a manner sensitive to sulfasalazine. These results suggest that NF-kappaB contributes to the IL-1-induced degradation of collagen by corneal fibroblasts and is therefore a potential therapeutic target for treatment of corneal ulcers.
Stepp, Mary Ann; Tadvalkar, Gauri; Hakh, Raymond; Pal-Ghosh, Sonali
The eye is innervated by neurons derived from both the central nervous system and peripheral nervous system (PNS). While much is known about retinal neurobiology and phototransduction, less attention has been paid to the innervation of the eye by the PNS and the roles it plays in maintaining a functioning visual system. The ophthalmic branch of the trigeminal ganglion contains somas of neurons that innervate the cornea. These nerves provide sensory functions for the cornea and are referred to as intraepithelial corneal nerves (ICNs) consisting of subbasal nerves and their associated intraepithelial nerve terminals. ICNs project for several millimeters within the corneal epithelium without Schwann cell support. Here, we present evidence for the hypothesis that corneal epithelial cells function as glial cells to support the ICNs. Much of the data supporting this hypothesis is derived from studies of corneal development and the reinnervation of the ICNs in the rodent and rabbit cornea after superficial wounds. Corneal epithelial cells activate in response to injury via mechanisms similar to those induced in Schwann cells during Wallerian Degeneration. Corneal epithelial cells phagocytize distal axon fragments within hours of ICN crush wounds. During aging, the proteins, lipids, and mitochondria within the ICNs become damaged in a process exacerbated by UV light. We propose that ICNs shed their aged and damaged termini and continuously elongate to maintain their density. Available evidence points to new unexpected roles for corneal epithelial cells functioning as surrogate Schwann cells for the ICNs during homeostasis and in response to injury. GLIA 2017;65:851-863. © 2016 Wiley Periodicals, Inc.
Razmjoo, Hassan; Abtahi, Mohammad-Ali; Roomizadeh, Peyman; Mohammadi, Zahra; Abtahi, Seyed-Hossein
Corneal bee sting is an uncommon environmental eye injury that can result in various ocular complications with an etiology of penetrating, immunologic, and toxic effects of the stinger and its injected venom. In this study we present our experience in the management of a middle-aged male with a right-sided deep corneal bee sting. On arrival, the patient was complaining of severe pain, blurry vision with acuity of 160/200, and tearing, which he had experienced soon after the injury. Firstly, we administered conventional drugs for eye injuries, including topical antibiotic, corticosteroid, and cycloplegic agents. After 2 days, corneal stromal infiltration and edema developed around the site of the sting, and visual acuity decreased to 100/200. These conditions led us to remove the stinger surgically. Within 25 days of follow-up, the corneal infiltration decreased gradually, and visual acuity improved to 180/200. We suggest a two-stage management approach for cases of corneal sting. For the first stage, if the stinger is readily accessible or primary dramatic reactions, including infiltration, especially on the visual axis, exist, manual or surgical removal would be indicated. Otherwise, we recommend conventional treatments for eye injuries. Given this situation, patients should be closely monitored for detection of any worsening. If the condition does not resolve or even deteriorates, for the second stage, surgical removal of the stinger under local or generalized anesthesia is indicated.
Stepp, Mary Ann
Integrins were first described just over 20 years ago and have been studied in the cornea by many groups interested in how the cornea functions in health and disease. There are a minimum of 12 different integrin heterodimers reported to be expressed by the major resident cells of the cornea: the corneal and limbal epithelial cells, keratocytes/fibroblasts, and corneal endothelial cells. These different integrin heterodimers play important and varied roles in maintaining the cornea and organizing how its cells interact with their surrounding extracellular matrix to maintain corneal clarity. In this review, an overview of the discovery and functions of integrins is provided along with a description of the current state of our knowledge of this large family of important proteins. While we have learned a lot about corneal integrins over the past 20 years, there is still much to learn. Areas where gaps in our knowledge of integrin functions in the cornea are slowing our progress in understanding corneal diseases and dystrophies at a molecular level are highlighted.
Kerr, Peter J; Donnelly, Thomas M
Viral diseases of rabbits have been used historically to study oncogenesis (e.g. rabbit fibroma virus, cottontail rabbit papillomavirus) and biologically to control feral rabbit populations (e.g. myxoma virus). However, clinicians seeing pet rabbits in North America infrequently encounter viral diseases although myxomatosis may be seen occasionally. The situation is different in Europe and Australia, where myxomatosis and rabbit hemorrhagic disease are endemic. Advances in epidemiology and virology have led to detection of other lapine viruses that are now recognized as agents of emerging infectious diseases. Rabbit caliciviruses, related to rabbit hemorrhagic disease, are generally avirulent, but lethal variants are being identified in Europe and North America. Enteric viruses including lapine rotavirus, rabbit enteric coronavirus and rabbit astrovirus are being acknowledged as contributors to the multifactorial enteritis complex of juvenile rabbits. Three avirulent leporid herpesviruses are found in domestic rabbits. A fourth highly pathogenic virus designated leporid herpesvirus 4 has been described in Canada and Alaska. This review considers viruses affecting rabbits by their clinical significance. Viruses of major and minor clinical significance are described, and viruses of laboratory significance are mentioned. Copyright © 2013 Elsevier Inc. All rights reserved.
... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Corneal electrode. 886.1220 Section 886.1220 Food... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1220 Corneal electrode. (a) Identification. A corneal electrode is an AC-powered device, usually part of a special contact lens, intended to be applied directly...
... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Corneal electrode. 886.1220 Section 886.1220 Food... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1220 Corneal electrode. (a) Identification. A corneal electrode is an AC-powered device, usually part of a special contact lens, intended to be applied directly...
... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Corneal electrode. 886.1220 Section 886.1220 Food... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1220 Corneal electrode. (a) Identification. A corneal electrode is an AC-powered device, usually part of a special contact lens, intended to be applied directly...
... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Corneal electrode. 886.1220 Section 886.1220 Food... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1220 Corneal electrode. (a) Identification. A corneal electrode is an AC-powered device, usually part of a special contact lens, intended to be applied directly...
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Corneal electrode. 886.1220 Section 886.1220 Food... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1220 Corneal electrode. (a) Identification. A corneal electrode is an AC-powered device, usually part of a special contact lens, intended to be applied directly...
Wang, Liqiang; Shankarappa, Sahadev A.; Tong, Rong; Ciolino, Joseph B.; Tsui, Jonathan H.; Chiang, Homer H.; Kohane, Daniel S.
Purpose Ocular local anesthetics (OLA’s) currently used in routine clinical practice for corneal anesthesia are short acting and their ability to delay corneal healing makes them unsuitable for long-term use. In this study, we examined the effect on the duration of corneal anesthesia of the site-1 sodium channel blocker tetrodotoxin (TTX), applied with either proparacaine or the chemical permeation enhancer OTAB. The effect of test solutions on corneal healing was also studied. Methods Solutions of TTX, proparacaine, and OTAB, singly or in combination were applied topically to the rat cornea. The blink response, an indirect measure of corneal sensitivity, was recorded using a Cochet-Bonnet esthesiometer, and the duration of corneal anesthesia calculated. The effect of test compounds on the rate of corneal epithelialization was studied in vivo following corneal debridement. Results Combination of TTX and proparacaine resulted in corneal anesthesia that was 8–10 times longer in duration than that from either drug administered alone, while OTAB did not prolong anesthesia. The rate of corneal healing was moderately delayed following co-administration of TTX and proparacaine. Conclusion Co-administration of TTX and proparacaine significantly prolonged corneal anesthesia but in view of delayed corneal re-epithelialization, caution is suggested in use of the combination. PMID:23615270
Badial, Peres R; Cisneros-Àlvarez, Luis Emiliano; Brandão, Cláudia Valéria S; Ranzani, José Joaquim T; Tomaz, Mayana A R V; Machado, Vania M; Borges, Alexandre S
The aim of this study was to compare ocular dimensions, corneal curvature, and corneal thickness between horses affected with hereditary equine regional dermal asthenia (HERDA) and unaffected horses. Five HERDA-affected quarter horses and five healthy control quarter horses were used. Schirmer's tear test, tonometry, and corneal diameter measurements were performed in both eyes of all horses prior to ophthalmologic examinations. Ultrasonic pachymetry was performed to measure the central, temporal, nasal, dorsal, and ventral corneal thicknesses in all horses. B-mode ultrasound scanning was performed on both eyes of each horse to determine the dimensions of the ocular structures and to calculate the corneal curvature. Each corneal region examined in this study was thinner in the affected group compared with the healthy control group. However, significant differences in corneal thickness were only observed for the central and dorsal regions. HERDA-affected horses exhibited significant increases in corneal curvature and corneal diameter compared with unaffected animals. The ophthalmologic examinations revealed mild corneal opacity in one eye of one affected horse and in both eyes of three affected horses. No significant between-group differences were observed for Schirmer's tear test, intraocular pressure, or ocular dimensions. Hereditary equine regional dermal asthenia-affected horses exhibit decreased corneal thickness in several regions of the cornea, increased corneal curvature, increased corneal diameter, and mild corneal opacity. Additional research is required to determine whether the increased corneal curvature significantly impacts the visual accuracy of horses with HERDA. © 2014 American College of Veterinary Ophthalmologists.
Maharana, Prafulla K; Sharma, Namrata; Vajpayee, Rasik B
Acute corneal hydrops is a condition characterized by stromal edema due to leakage of aqueous through a tear in descemet membrane. The patient presents with sudden onset decrease in vision, photophobia, and pain. Corneal thinning and ectasias combined with trivial trauma to the eye mostly by eye rubbing is considered as the underlying cause. With conservative approach self-resolution takes around 2 to 3 months. Surgical intervention is required in cases of non-resolution of corneal edema to avoid complications and for early visual rehabilitation. Intracameral injection of air or gas such as perflouropropane is the most common surgical procedure done. Recent investigative modality such as anterior segment optical coherence tomography is an extremely useful tool for diagnosis, surgical planning, and postoperative follow up. Resolution of hydrops may improve the contact lens tolerance and visual acuity but most cases require keratoplasty for visual rehabilitation. PMID:23925338
Qazi, Yureeda; Hamrah, Pedram
Corneal transplantation is the most commonly performed organ transplantation. Immune privilege of the cornea is widely recognized, partly because of the relatively favorable outcome of corneal grafts. The first-time recipient of corneal allografts in an avascular, low-risk setting can expect a 90% success rate without systemic immunosuppressive agents and histocompatibility matching. However, immunologic rejection remains the major cause of graft failure, particularly in patients with a high risk for rejection. Corticosteroids remain the first-line therapy for the prevention and treatment of immune rejection. However, current pharmacological measures are limited in their side-effect profiles, repeated application, lack of targeted response, and short duration of action. Experimental ocular gene therapy may thus present new horizons in immunomodulation. From efficient viral vectors to sustainable alternative splicing, we discuss the progress of gene therapy in promoting graft survival and postulate further avenues for gene-mediated prevention of allogeneic graft rejection. PMID:24138037
Li, Li; Zhou, Dilys; Wang, Xiu-mei; Wang, Xiao-ping; Cui, Fu-zhai; Lu, Yu-jie; Huang, Yi-fei
To investigate the expression of matrix metalloproteinase-2 (MMP-2) and Tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) in rabbit corneas implanted with modified titanium skirt of keratoprosthesis in order to explore the potential roles. A total of 20 New Zealand white rabbits with corneal alkali burn in right eye rabbit corneas were divided into three groups. There were 6 animals in each group. Skirt of hydroxyapatite/Sandblast-Titanium and Sandblast-Titanium were inserted into the corneal stroma of rabbits in group A and group B. The group C did not insert skirt as surgical control.2 rabbits were as normal control D group. A total of 20 New Zealand white rabbits were divided into four groups with the same way. The expression of MMP-2 and TIMP-2 was determined by immunohistochemistry at 1 month, 3 months. The expression of MMP-2 and TIMP-2 mRNA level was determined by real time-polymerase chain reaction, and its protein level was determined by western blot. The optical cylinder was implanted to rabbit corneas, which were implanted with modified titanium skirt after 3 months. There was one case of corneal dissolution being found in group F. MMP-2 and TIMP-2 immunoreactivities were expressed in the normal corneas, predominantly in the corneal epithelium. After injury, immunoreactivities of both MMP-2 and TIMP-2 were increased notably in the healing corneal epithelium, infiltrating inflammatory cells, stromal fibroblasts and in growing vascular endothelial cells. The expression of MMP-2 was lower in group A and E than that in group B and F after 1 month and 3 months (t = 12.05, 2.93, 12.006, 3.781, P < 0.05). The Western blot revealed no significant differences of MMP-2 mRNA between group 3 months and 2 weeks (t = 2.104, P > 0.05); MMP-2 immunoreactivities were absent or lowly expressed predominantly in the corneal epithelium of normal corneas. The expression of MMP-2, TIMP-2 mRNA level was parallel that of protein level. The expression of MMP-2 was lower in
Moffatt, S Louise; Cartwright, Victoria A; Stumpf, Thomas H
Abstract One hundred years ago, on 7 December 1905, Dr Eduard Zirm performed the world's first successful human corneal transplant. This significant milestone was achieved only after many decades of unsuccessful trial and error; however, it did not lead to relatively 'routine' keratoplasty success for several more decades. The idea of replacing an opaque cornea had been suggested for centuries, and had stimulated theoretical approaches to the problem by many esteemed physicians throughout history. However, little practical progress was made in the ultimate realization of the dream until the 19th century when pioneering surgeons pursued extensive studies in relation to both animal and human 'keratoplasty'. Clinical progress and scientific insight developed slowly, and it was ultimately due to parallel advances in medicine such as anaesthesia and antisepsis that Zirm's success was finally achieved. Key concepts were enshrined such as the use of fresh tissue from the same species, careful placement and handling of tissue, and the development of specialized instrumentation such as the circular trephine. In the latter half of the 20th century, many 'masters' of corneal surgery evolved significant refinements in technique and instrumentation with the development of corticosteroids, antibiotics, surgical microscopes, improved trephines, viscoelastics and suture materials, that enable this delicate procedure to be routinely performed with the prospect of success. There are still limitations to corneal transplantation, and corneal allograft rejection still poses the greatest challenge to the modern corneal surgeon. In the foreseeable future it may be in the laboratory, rather than the theatre, that further milestones will be achieved. This review aims to highlight the significant milestones in the rich history of corneal transplantation, and to pay tribute to the many inspired and dedicated individuals involved in the development of keratoplasty to a point where the
Kim, Tae-im; Tchah, Hungwon; Cho, Eun Hee; Kook, Michael S
To investigate the effects of alcohol and mitomycin C (MMC) on cultured corneal fibroblast of the rabbit to determine the safety of this compound for clinical use. Corneal fibroblasts of New Zealand rabbits were cultured. Various concentrations (0%, 10%, 20%, 30%, 40%, and 60%) of ethanol were applied for 10, 20, 30, and 40 seconds to estimate dose- and time-dependent responses of cultured corneal fibroblasts. Cell viability was assessed using the MTT assay. Treated cells were additionally stained with Hoechst and annexin V for the identification of apoptosis. To investigate the coeffects of ethanol and MMC, dose and time dependency were evaluated after treatment with various concentrations of ethanol and MMC at different exposure times, and cell viability was established. To determine the latent effects of ethanol and MMC, cultured corneal fibroblasts were cotreated with various concentrations of ethanol and 0.02% MMC for various periods and washed out, and then one group was incubated for 24 hours and another group was not incubated. Cell viability was estimated, and Hoechst and annexin V staining were performed before and after incubation. To establish the pathway of cell death, caspase-3 activities were measured in cultured corneal fibroblasts treated with ethanol or MMC. Cell viability after ethanol treatment was dose and time dependent. After application of ethanol for 10 seconds, cell viability was significantly reduced with 20% ethanol (P = 0.001). At 20, 30, and 40 seconds of treatment with 10% ethanol, cell viability was significantly reduced (P < 0.01). Hoechst and annexin V staining revealed typical characteristics of apoptosis, such as bright fluorescent chromatin condensation, low fluorescence of nuclear fragmentation, and cell membrane shrinkage. Cell viability was more significantly reduced after cotreatment with alcohol and MMC, compared with treatment with alcohol alone. Moreover, cell viability was considerably decreased in the incubated group
Asgharian, Bahman; Price, Owen; Kabilan, Senthil; Jacob, Richard E.; Einstein, Daniel R.; Kuprat, Andrew P.; Corley, Richard A.
Despite using rabbits in several inhalation exposure experiments to study diseases such as anthrax, there is a lack of understanding regarding deposition characteristics and fate of inhaled particles (bio-aerosols and viruses) in the respiratory tracts of rabbits. Such information allows dosimetric extrapolation to humans to inform human outcomes. The lung geometry of the New Zealand white rabbit (referred to simply as rabbits throughout the article) was constructed using recently acquired scanned images of the conducting airways of rabbits and available information on its acinar region. In addition, functional relationships were developed for the lung and breathing parameters of rabbits as a function of body weight. The lung geometry and breathing parameters were used to extend the existing deposition model for humans and several other species to rabbits. Evaluation of the deposition model for rabbits was made by comparing predictions with available measurements in the literature. Deposition predictions in the lungs of rabbits indicated smaller deposition fractions compared to those found in humans across various particle diameter ranges. The application of the deposition model for rabbits was demonstrated by extrapolating deposition predictions in rabbits to find equivalent human exposure concentrations assuming the same dose-response relationship between the two species. Human equivalent exposure concentration levels were found to be much smaller than those for rabbits.
Asgharian, Bahman; Price, Owen; Kabilan, Senthil; Jacob, Richard E; Einstein, Daniel R; Kuprat, Andrew P; Corley, Richard A
Despite using rabbits in several inhalation exposure experiments to study diseases such as anthrax, there is a lack of understanding regarding deposition characteristics and fate of inhaled particles (bio-aerosols and viruses) in the respiratory tracts of rabbits. Such information allows dosimetric extrapolation to humans to inform human outcomes. The lung geometry of the New Zealand white rabbit (referred to simply as rabbits throughout the article) was constructed using recently acquired scanned images of the conducting airways of rabbits and available information on its acinar region. In addition, functional relationships were developed for the lung and breathing parameters of rabbits as a function of body weight. The lung geometry and breathing parameters were used to extend the existing deposition model for humans and several other species to rabbits. Evaluation of the deposition model for rabbits was made by comparing predictions with available measurements in the literature. Deposition predictions in the lungs of rabbits indicated smaller deposition fractions compared to those found in humans across various particle diameter ranges. The application of the deposition model for rabbits was demonstrated by extrapolating deposition predictions in rabbits to find equivalent human exposure concentrations assuming the same dose-response relationship between the two species. Human equivalent exposure concentration levels were found to be much smaller than those for rabbits.
Mrochen, Michael; Jankov, Mirko; Bueeler, Michael; Seiler, Theo
Purpose: Corneal topography data expressed as corneal aberrations are frequently used to report corneal laser surgery results. However, the optical image quality at the retina depends on all optical elements of the eye such as the human lens. Thus, the aim of this study was to investigate the correlations between the corneal and total wavefront aberrations and to discuss the importance of corneal aberrations for representing corneal laser surgery results. Methods: Thirty three eyes of 22 myopic subjects were measured with a corneal topography system and a Tschernig-type wavefront analyzer after the pupils were dilated to at least 6 mm in diameter. All measurements were centered with respect to the line of sight. Corneal and total wavefront aberrations were calculated up to the 6th Zernike order in the same reference plane. Results: Statistically significant correlations (p < 0.05) between the corneal and total wavefront aberrations were found for the astigmatism (C3,C5) and all 3rd Zernike order coefficients such as coma (C7,C8). No statistically significant correlations were found for all 4th to 6th order Zernike coefficients except for the 5th order horizontal coma C18 (p equals 0.003). On average, all Zernike coefficients for the corneal aberrations were found to be larger compared to Zernike coefficients for the total wavefront aberrations. Conclusions: Corneal aberrations are only of limited use for representing the optical quality of the human eye after corneal laser surgery. This is due to the lack of correlation between corneal and total wavefront aberrations in most of the higher order aberrations. Besides this, the data present in this study yield towards an aberration balancing between corneal aberrations and the optical elements within the eye that reduces the aberration from the cornea by a certain degree. Consequently, ideal customized ablations have to take both, corneal and total wavefront aberrations, into consideration.
Ljubimov, Alexander V.; Saghizadeh, Mehrnoosh
Corneal wound healing is a complex process involving cell death, migration, proliferation, differentiation, and extracellular matrix remodeling. Many similarities are observed in the healing processes of corneal epithelial, stromal and endothelial cells, as well as cell-specific differences. Corneal epithelial healing largely depends on limbal stem cells and remodeling of the basement membrane. During stromal healing, keratocytes get transformed to motile and contractile myofibroblasts largely due to activation of transforming growth factor-β system. Endothelial cells heal mostly by migration and spreading, with cell proliferation playing a secondary role. In the last decade, many aspects of wound healing process in different parts of the cornea have been elucidated, and some new therapeutic approaches have emerged. The concept of limbal stem cells received rigorous experimental corroboration, with new markers uncovered and new treatment options including gene and microRNA therapy tested in experimental systems. Transplantation of limbal stem cell-enriched cultures for efficient re-epithelialization in stem cell deficiency and corneal injuries has become reality in clinical setting. Mediators and course of events during stromal healing have been detailed, and new treatment regimens including gene (decorin) and stem cell therapy for excessive healing have been designed. This is a very important advance given the popularity of various refractive surgeries entailing stromal wound healing. Successful surgical ways of replacing the diseased endothelium have been clinically tested, and new approaches to accelerate endothelial healing and suppress endothelial-mesenchymal transformation have been proposed including Rho kinase (ROCK) inhibitor eye drops and gene therapy to activate TGF-β inhibitor SMAD7. Promising new technologies with potential for corneal wound healing manipulation including microRNA, induced pluripotent stem cells to generate corneal epithelium, and
Yoder, Paul R.; Macri, Timothy F.; Telfair, William B.; Bennett, Peter S.; Martin, Clifford A.; Warner, John W.
We describe a new electro-optical device being developed to provide precise measurements of the three-dimensional topography of the human cornea. This device, called a digital keratoscope, is intended primarily for use in preparing for and determining the effect of corneal surgery procedures such as laser refractive keratectomy, radial keratotomy or corneal transplant on the refractive power of the cornea. It also may serve as an aid in prescribing contact lenses. The basic design features of the hardware and of the associated computer software are discussed, the means for alignment and calibration are described and typical results are given.
Zarranz Ventura, J; De Nova, E; Moreno-Montañés, J
Systemic diseases affecting the cornea have a wide range of manifestations. The detailed study of all pathologies that cause corneal alteration is unapproachable, so we have centered our interest in the most prevalent or characteristic of them. In this paper we have divided these pathologies in sections to facilitate their study. Pulmonar and conective tissue (like colagen, rheumatologic and idiopathic inflamatory diseases), dermatologic, cardiovascular, hematologic, digestive and hepatopancreatic diseases with corneal alteration are described. Endocrine and metabolic diseases, malnutrition and carential states are also studied, as well as some otorhinolaryngologic and genetic diseases that affect the cornea. Finally, a brief report of ocular toxicity induced by drugs is referred.
Alnawaiseh, Maged; Zumhagen, Lars; Wirths, Gabriele; Eveslage, Maria; Eter, Nicole; Rosentreter, André
The aim of the study was to quantify Scheimpflug corneal densitometry in patients with Fuchs endothelial dystrophy (FED). In this study, we retrospectively reviewed the charts and anterior segment data of 49 patients with FED before posterior lamellar keratoplasty and 51 healthy controls. The patients were examined using the Scheimpflug-based Oculus Pentacam. Central corneal thickness (CCT), ring-averaged (on a circle of 2, 2.4-10 mm diameter) noncentral corneal thickness, and densitometry data in different corneal layers and in different annuli were extracted and analyzed. The total corneal light backscatter at total corneal thickness (CT) and at total diameter was significantly higher in the FED group when compared with the control group (FED group: 28.8 ± 6.7; control group: 24.3 ± 4.1; P < 0.001). When the corneal surface was divided into concentric annular zones at total CT, the differences were significant only in the 2 central annuli (P < 0.001). The total corneal light backscatter at total CT in the central 0-2 mm annulus correlated moderately with the central corneal thickness (Pearson's correlation = 0.55, P < 0.001). Corneal light backscatter in the central cornea was greater in patients with FED than in normal subjects. Corneal densitometry enables us to evaluate the optical quality of the cornea in different corneal layers and in different annuli. It is a useful, objective method that, in combination with central corneal thickness and corneal central-to-peripheral thickness ratio, can help to quantify FED severity.
Urs, Raksha; Lloyd, Harriet O; Silverman, Ronald H
To noninvasively measure changes in corneal biomechanical properties induced by ultraviolet-activated riboflavin cross-linking therapy using acoustic radiation force (ARF). Cross-linking was performed on the right eyes of 6 rabbits, with the left eyes serving as controls. Acoustic radiation force was used to assess corneal stiffness before treatment and weekly for 4 weeks after treatment. Acoustic power levels were within US Food and Drug Administration guidelines for ophthalmic safety. Strain, determined from ARF-induced displacement of the front and back surfaces of the cornea, was fit to the Kelvin-Voigt model to determine the elastic modulus (E) and coefficient of viscosity (η). The stiffness factor, the ratio of E after treatment to E before treatment, was calculated for treated and control eyes. At the end of 4 weeks, ex vivo thermal shrinkage temperature analysis was performed for comparison with in vivo stiffness measurements. One-way analysis of variance and Student t tests were performed to test for differences in E, η, the stiffness factor, and corneal thickness. Biomechanical stiffening was immediately evident in cross-linking-treated corneas. At 4 weeks after treatment, treated corneas were 1.3 times stiffer and showed significant changes in E (P= .006) and η (P= .007), with no significant effect in controls. Corneal thickness increased immediately after treatment but did not differ significantly from the pretreatment value at 4 weeks. Our findings demonstrate a statistically significant increase in stiffness in cross-linking-treated rabbit corneas based on in vivo axial stress/strain measurements obtained using ARF. The capacity to noninvasively monitor corneal stiffness offers the potential for clinical monitoring of cross-linking therapy. © 2014 by the American Institute of Ultrasound in Medicine.