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He Y, Ma BS, Zeng JH, Ma DJ. Corneal optical density: Structural basis, measurements, influencing factors, and roles in refractive surgery. Front Bioeng Biotechnol 2023; 11:1144455. [PMID: 37091331 PMCID: PMC10117965 DOI: 10.3389/fbioe.2023.1144455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 03/29/2023] [Indexed: 04/08/2023] Open
Abstract
The cornea is the main refractive medium of the human eye, and its clarity is critical to visual acuity. Corneal optical density (COD) is an important index to describe corneal transparency. Intact corneal epithelial and endothelial cells, regular arrangement of collagen fibers in the stroma, and normal substance metabolism are all integral for the cornea to maintain its transparency. In the last two decades, the Pentacam Scheimpflug imaging system has emerged as a breakthrough for the measurement of COD (also called corneal densitometry). It has been found that a wide variety of factors such as age, refractive status, and corneal diseases can affect COD. Different corneal refractive surgery methods also change COD in different corneal regions and layers and affect visual acuity following the surgery. Thus, COD has gradually become a significant indicator to evaluate corneal health, one on which the attention of clinicians has been increasingly focused.
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Affiliation(s)
- Ye He
- Changsha Aier Eye Hospital, Changsha, China
| | - Bo-Sheng Ma
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Jun-Hao Zeng
- Xiangya School of Medicine, Central South University, Changsha, China
| | - Dai-Jin Ma
- Changsha Aier Eye Hospital, Changsha, China
- *Correspondence: Dai-Jin Ma,
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The TGM2 inhibitor cysteamine hydrochloride does not impact corneal epithelial and stromal wound healing in vitro and in vivo. Exp Eye Res 2023; 226:109338. [PMID: 36470430 PMCID: PMC10120528 DOI: 10.1016/j.exer.2022.109338] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 11/21/2022] [Accepted: 11/28/2022] [Indexed: 12/12/2022]
Abstract
Corneal wound healing is integral for resolution of corneal disease or for post-operative healing. However, corneal scarring that may occur secondary to this process can significantly impair vision. Tissue transglutaminase 2 (TGM2) inhibition has shown promising antifibrotic effects and thus holds promise to prevent or treat corneal scarring. The commercially available ocular solution for treatment of ocular manifestations of Cystinosis, Cystaran®, contains the TGM2 inhibitor cysteamine hydrochloride (CH). The purpose of this study is to assess the safety of CH on corneal epithelial and stromal wounds, its effects on corneal wound healing, and its efficacy against corneal scarring following wounding. Quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC) were first used to quantify and localize TGM2 expression in the cornea. Subsequently, (i) the in vitro effects of CH at 0.163, 1.63, and 16.3 mM on corneal epithelial cell migration was assessed with an epithelial cell migration assay, and (ii) the in vivo effects of application of 1.63 mM CH on epithelial and stromal wounds was assessed in a rabbit model with ophthalmic examinations, inflammation scoring, color and fluorescein imaging, optical coherence tomography (OCT), and confocal biomicroscopy. Post-mortem assessment of corneal tissue post-stromal wounding included biomechanical characterization (atomic force microscopy (AFM)), histology (H&E staining), and determining incidence of myofibroblasts (immunostaining against α-SMA) in wounded corneal tissue. TGM2 expression was highest in corneal epithelial cells. Application of the TGM2 inhibitor CH did not affect in vitro epithelial cell migration at the two lower concentrations tested. At 16.3 mM, decreased cell migration was observed. In vivo application of CH at 57 mM was well tolerated and did not adversely affect wound healing. No difference in corneal scarring was found between CH treated and vehicle control eyes. This study shows that the TGM2 inhibitor CH, at the FDA-approved dose, is well tolerated in a rabbit model of corneal wound healing and does not adversely affect epithelial or stromal wound healing. This supports the safe use of this medication in Cystinosis patients with open corneal wounds. CH did not have an effect on corneal scarring in this study, suggesting that Cystaran® administration to patients with corneal wounds is unlikely to decrease corneal fibrosis.
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Berkowski WM, Gibson DJ, Seo S, Proietto LR, Whitley RD, Schultz GS, Plummer CE. Assessment of Topical Therapies for Improving the Optical Clarity Following Stromal Wounding in a Novel Ex Vivo Canine Cornea Model. ACTA ACUST UNITED AC 2018; 59:5509-5521. [DOI: 10.1167/iovs.17-23085] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- William M. Berkowski
- Department of Small Animal Clinical Sciences, University of Florida, Gainesville, Florida, United States
| | - Daniel J. Gibson
- Institute for Wound Research, University of Florida, Gainesville, Florida, United States
| | - SooJung Seo
- Institute for Wound Research, University of Florida, Gainesville, Florida, United States
| | - Laura R. Proietto
- Department of Small Animal Clinical Sciences, University of Florida, Gainesville, Florida, United States
| | - R. David Whitley
- Department of Small Animal Clinical Sciences, University of Florida, Gainesville, Florida, United States
| | - Gregory S. Schultz
- Institute for Wound Research, University of Florida, Gainesville, Florida, United States
| | - Caryn E. Plummer
- Department of Small Animal Clinical Sciences, University of Florida, Gainesville, Florida, United States
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Feng X, Pi L, Sriram S, Schultz GS, Gibson DJ. Connective tissue growth factor is not necessary for haze formation in excimer laser wounded mouse corneas. PLoS One 2017; 12:e0172304. [PMID: 28207886 PMCID: PMC5313228 DOI: 10.1371/journal.pone.0172304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 02/02/2017] [Indexed: 11/19/2022] Open
Abstract
We sought to determine if connective tissue growth factor (CTGF) is necessary for the formation of corneal haze after corneal injury. Mice with post-natal, tamoxifen-induced, knockout of CTGF were subjected to excimer laser phototherapeutic keratectomy (PTK) and the corneas were allowed to heal. The extent of scaring was observed in non-induced mice, heterozygotes, and full homozygous knockout mice and quantified by macrophotography. The eyes from these mice were collected after euthanization for re-genotyping to control for possible Cre-mosaicism. Primary corneal fibroblasts from CTGF knockout corneas were established in a gel plug assay. The plug was removed, simulating an injury, and the rate of hole closure and the capacity for these cells to form light reflecting cells in response to CTGF and platelet-derived growth factor B (PDGF-B) were tested and compared to wild-type cells. We found that independent of genotype, each group of mice was still capable of forming light reflecting haze in the cornea after laser ablation (p = 0.40). Results from the gel plug closure rate in primary cell cultures of knockout cells were not statistically different from serum starved wild-type cells, independent of treatment. Compared to the serum starved wild-type cells, stimulation with PDGF-BB significantly increased the KO cell culture’s light reflection (p = 0.03). Most interestingly, both reflective cultures were positive for α-SMA, but the cellular morphology and levels of α-SMA were distinct and not in proportion to the light reflection seen. This new work demonstrates that corneas without CTGF can still form sub-epithelial haze, and that the light reflecting phenotype can be reproduced in culture. These data support the possibilities of growth factor redundancy and that multiple pro-haze pathways exist.
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Affiliation(s)
- Xiaodi Feng
- Institute of Wound Research, University of Florida, Gainesville, Florida, United States of America
| | - Liya Pi
- Department of Pediatrics, University of Florida, Gainesville, Florida, United States of America
| | - Sriniwas Sriram
- Department of Biomedical Engineering, University of Florida, Gainesville, Florida, United States of America
| | - Gregory S. Schultz
- Institute of Wound Research, University of Florida, Gainesville, Florida, United States of America
| | - Daniel J. Gibson
- Institute of Wound Research, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
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Proietto LR, Whitley RD, Brooks DE, Schultz GE, Gibson DJ, Berkowski WM, Salute ME, Plummer CE. Development and Assessment of a Novel Canine Ex Vivo Corneal Model. Curr Eye Res 2017; 42:813-821. [PMID: 28128981 DOI: 10.1080/02713683.2016.1262428] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
PURPOSE To develop a novel ex vivo extended culture model of canine corneal epithelial cell wound healing. MATERIALS AND METHODS Canine corneoscleral rims (CSR) were obtained and, after preparation for culture, were placed on a nutating scaffold and incubated in physiological conditions. In experiment 1, eight CSR in a serum-containing antimicrobial-fortified medium were monitored for epithelial integrity and bacterial infection up to 28 days in culture. CSR were assessed histologically at the end of the culture period end points 0, 7, 14, and 28 days with accompanying scanning electron microscopic (SEM) and transmission electron microscopic (TEM) evaluation. Samples for microbial culture were obtained at days 0, 3, 7, 14, and 28. In experiment 2, uniform 8-mm-diameter superficial corneal epithelial wounds were created and monitored for re-epithelialization in the same culture conditions or in a serum-free protein equivalent medium, with four CSR per group. Standardized digital images were obtained with cobalt filter at the time of fluorescein staining and media change every six hours. Image J imaging software was used to measure the area of fluorescein retention. Re-epithelialization rates were calculated and CSR then fixed for immunohistochemistry (IHC). RESULTS All corneas survived to end points as described in experiment 1 with no evidence of contamination or compromised epithelial integrity. Histologically, a multilayered epithelium was maintained and corneal edema was not appreciated until day 14. SEM examination revealed epithelial cell layer confluence and migrating epithelial cells of normal cellular morphology with normal cell-cell interactions on TEM. In experiment 2, all eight corneas healed with a healing rate of 0.702 ± 0.130 mm2/h (1.25 mm/day epithelial cell migration rate) and were positive in IHC evaluation for markers of corneal fibrosis. CONCLUSION This ex vivo canine corneal wound healing model is an appropriate and clinically relevant tool for assessment and modulation of epithelial wound healing.
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Affiliation(s)
- Laura R Proietto
- a Department of Small Animal Clinical Sciences , University of Florida College of Veterinary Medicine , Gainesville , FL , USA
| | - R David Whitley
- a Department of Small Animal Clinical Sciences , University of Florida College of Veterinary Medicine , Gainesville , FL , USA
| | - Dennis E Brooks
- a Department of Small Animal Clinical Sciences , University of Florida College of Veterinary Medicine , Gainesville , FL , USA
| | - Gregory E Schultz
- b Institute for Wound Research, Department of Obstetrics and Gynecology , University of Florida College of Medicine , Gainesville , FL , USA
| | - Daniel J Gibson
- b Institute for Wound Research, Department of Obstetrics and Gynecology , University of Florida College of Medicine , Gainesville , FL , USA
| | - William M Berkowski
- a Department of Small Animal Clinical Sciences , University of Florida College of Veterinary Medicine , Gainesville , FL , USA
| | - Marc E Salute
- a Department of Small Animal Clinical Sciences , University of Florida College of Veterinary Medicine , Gainesville , FL , USA
| | - Caryn E Plummer
- a Department of Small Animal Clinical Sciences , University of Florida College of Veterinary Medicine , Gainesville , FL , USA
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Modi KK, Chu DS, Wagner RS, Guo S, Zarbin MA, Bhagat N. Infectious Ulcerative Keratitis Following Retinopathy of Prematurity Treatment. J Pediatr Ophthalmol Strabismus 2015; 52:221-5. [PMID: 26065410 DOI: 10.3928/01913913-20150602-01] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 01/30/2015] [Indexed: 11/20/2022]
Abstract
PURPOSE To report the complication of infectious ulcerative keratitis after laser photocoagulation and pars plana vitrectomy (PPV) for retinopathy of prematurity (ROP). METHODS A retrospective chart review of infants treated for ROP with plus disease between 2004 and 2013 at University Hospital, Newark, New Jersey. RESULTS Of the 110 eyes (55 patients) that underwent treatment for ROP, 8 (7.27%) eyes were noted to develop infectious ulcerative keratitis in 4 neonates (4 eyes after laser photocoagulation and 4 eyes after PPV). All 8 eyes that developed ulcerative keratitis had a preceding corneal epithelial defect followed by corneal stromal haze. Seven of 8 eyes developed epithelial defect within 8 days of the procedure. All epithelial defects progressed to ulcerative keratitis within 7 days. A total of 10 (9.1%) eyes developed postoperative epithelial defects, and 8 (80%) of these eyes were ultimately diagnosed as having ulcerative keratitis. Four (4.08%) of 98 eyes treated with laser photocoagulation alone developed infective ulcerative keratitis, compared to 4 (33.33%) of 12 eyes treated with PPV. Because keratitis healed, corneal opacification ensued and covered 10% to 90% of the corneal surface area. Five of the 8 eyes had positive culture of corneal scrapings: 2 grew coagulase-negative Staphylococcus and Stenotrophamonas; 1 grew coagulase-negative Staphylococcus; 1 grew Streptococcus viridans, and 1 grew Staphylococcus hominis, Streptococcus mitis, and Streptococcus viridans. All 8 eyes were treated with antibiotic eye drops. CONCLUSIONS Infectious ulcerative keratitis developed in a small, but significant, percentage of patients undergoing treatment for ROP. Postoperative corneal epithelial defects with subsequent corneal haze appear to be involved in the progression to ulcerative keratitis.
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Ibares-Frías L, Gallego P, Cantalapiedra-Rodríguez R, Valsero MC, Mar S, Merayo-Lloves J, Martínez-García MC. Tissue reaction after intrastromal corneal ring implantation in an experimental animal model. Graefes Arch Clin Exp Ophthalmol 2015; 253:1071-83. [PMID: 25744328 DOI: 10.1007/s00417-015-2959-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Revised: 01/22/2015] [Accepted: 01/27/2015] [Indexed: 01/04/2023] Open
Abstract
PURPOSE To evaluate corneal wound healing in the hen animal model after additive surgery with an intracorneal ring segment (ICRS). METHODS We implanted one ICRS in each eye of 76 hens. In control group 1 (n = 22 hens), the stromal channel was prepared but no ICRS was inserted. In control group 2 (n = 2 hens), no surgery was performed. Animals were randomly separated into groups and euthanized after clinical follow-up of 4 and 12 hours, 1, 2, 3, and 7 days, and 1, 2, 3, 4, and 6 months. Corneas were stained with hematoxylin-eosin. Apoptosis was measured by terminal uridine nick end-labeling assays. Cell proliferation and myofibroblast-like differentiation were assayed by BrdU and α-smooth muscle actin immunofluorescence microscopy. Stromal matrix changes were documented by electron microscopy. RESULTS Epithelial and stromal cell apoptosis around the ICRS-implanted and control group 1 eyes peaked at 12 hours, but continued for 72 hours. In ICRS-implanted eyes, epithelial and stromal proliferation was present at 12 and 24 hours, respectively, and peaked at 7 days and 72 hours, respectively. Some proliferation in the ICRS-implanted group continued through the 6-month follow-up, and myofibroblast-like cells differentiated one to three months after ICRS implantation. The segments rotated within the stroma as the limbal inferior angle approached the epithelium. CONCLUSIONS Wound healing after ICRS implantation in hen corneas was similar to that of other corneal surgical wounds in stages. However, there were some specific features related to the small size of the epithelial wound and the device permanently implanted inside the cornea.
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Affiliation(s)
- Lucía Ibares-Frías
- Group of Optical Diagnostic Techniques, Theorist, Atomic and Optical Physics Department, Faculty of Science, University of Valladolid, Valladolid, Spain,
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Gibson DJ, Pi L, Sriram S, Mao C, Petersen BE, Scott EW, Leask A, Schultz GS. Conditional knockout of CTGF affects corneal wound healing. Invest Ophthalmol Vis Sci 2014; 55:2062-70. [PMID: 24627144 DOI: 10.1167/iovs.13-12735] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE This study aimed to elucidate the role of connective tissue growth factor (CTGF) in healthy eyes and wounded corneas of mice and rabbits. Conditional knockout mice were used to determine the role of CTGF in corneal healing. METHODS CTGF expression was determined using transgenic mice carrying CTGF promoter driven-eGFP, quantitative RT-PCR, and immunofluorescent staining. Mice that carried two floxed CTGF alleles and a Cre/ERT2 transgene under the control of human ubiquitin C (ubc) promoter were used to conditionally delete CTGF gene in a tamoxifen-inducible manner. Phototherapeutic keratectomy (PTK) was used to generate an acute corneal wound and corneal re-epithelialization was assessed by fluorescein staining. RESULTS Connective tissue growth factor expression was found in multiple ocular tissues with relatively high levels in the corneal endothelium, lens subcapsular epithelium, and in the vasculature of the iris and retina. Wounded corneas responded with an immediate upregulation of CTGF in the epithelium at the wound margin and a sustained CTGF induction during re-epithelialization. At the onset of haze formation, CTGF protein becomes more focused in the basal epithelium. Deletion of the CTGF gene caused a 40% reduction (P < 0.01) in the cornea re-epithelialization rate in knockout mice compared with wild-type mice. CONCLUSIONS Connective tissue growth factor is expressed in the naïve cornea, lens, iris, and retina, and is expressed immediately after epithelial injury. Loss of CTGF impairs efficient re-epithelialization of corneal wounds.
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Affiliation(s)
- Daniel J Gibson
- Institute for Wound Research, University of Florida, Gainesville, Florida, United States
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