Effects of small leucine-rich proteoglycans on corneal transparency / 中华实验眼科杂志

Small leucine-rich proteoglycans (SLRPs) are necessary structural ingredients of the cornea, which are vital for the establishment and maintenance of corneal transparency.SLRPs are mainly located in the corneal stroma and can be divided into class Ⅰ, class Ⅱ, and class Ⅲ.The compensatory and cooperative interactions among SLRPs regulate the formation and assembly of stromal collagen fibrils, thereby maintaining the highly ordered arrangement of collagen fibrils, and establishing corneal transparency.Decorin and lumican are the main functional components of class Ⅰ and class Ⅱ SLRPs, respectively, and changes in their expression or abnormities in the structure of their core proteins affect the natural content and arrangement of other stromal extracellular matrix components, ultimately resulting in abnormal fibril formation, assembly, and arrangement, causing corneal opacity.SLRPs can regulate corneal wound healing and stromal matrix remodeling via binding to fibrotic molecules and their receptors, which provides bases for corneal diseases therapy and study of molecular mechanisms of corneal transparency.The bioactivities and the role of SLRPs in corneal transparency were reviewed in this article.

Advances in corneal wound healing and stroma remodeling / 中华实验眼科杂志

Stroma is the major part of cornea.The factors maintain corneal stroma transparency include the ultrastructural anatomy and physiology of the cornea and its cellular and extracellular components.During corneal development,neural crest cells and keratoblasts differentiate into keratocytes,which synthesize high levels of collagen and proteoglycans.The production and assembly of collagen fibers need a series of intracellular and extracellular components.The assembled collagen fibers deposite in ECM,assemble into high-order structures to synthesize small fiber bundles,and then form a larger structure in a particular tissue.Corneal wound healing is completed in highly coordinate by various cells and cytokines in time and space.The keratocytes phenotype changes and the remodeling of corneal stroma ECM are two important factors in this process.Corneal refractive surgery are carried out in the worldwide,although most corneal refractive surgery are successful,But the stromal opacity formed during the remodeling of corneal stroma is the most important cause of visual impairment and visual quality decline after refractive surgery.Well understanding the course of stroma remodeling after corneal injury,is meaningful for the exploration of decreasing corneal opacity formation.In this paper,the corneal stroma structure and its synthesis and assembly,the pathophysiological process of stroma remodeling in corneal wound healing and after corneal refractive surgery were reviewed.

Temporal and spatial distribution of TGF-β in corneal wound healing / 眼科新进展

Fibrosis is the major cause of corneal scarring.Transforming growth factor-beta (TGF-β) plays a key role in corneal homeostasis and repair.Corneal epithelial basement membrane is thought to be the important barrier of corneal epitheliumstroma interaction.In different stages of corneal wound healing,the isoforms of TGF-β have different temporal and spatial expression.The integrity of basement membrane is a critical factor of these procedures.The temporal and spatial distributions of TGF-β isoforms play the crucial roles in cell migration,proliferation,phenotype changes and deposition of extracellular matrix in corneal wound healing.It is the mechanism of corneal scarring and scar-free healing.This article reviews recent articles to elucidate the biological functions of TGF-β and the temporal and spatial distribution of its isoforms in corneal wound healing.

A Case of a Corneal Stromal Penetrating Injury via an Ejected Needle during Stromal Hydration

PURPOSE: We report a case of a horizontally penetrating injury of corneal stroma via an ejected irrigating needle during stromal hydration in cataract surgery. CASE SUMMARY: A 79-year-old woman presented with decreased visual acuity in her right eye. Her best corrected visual acuity in the right eye was 0.3. The cataract score of her right eye was nuclear opacity 3, cortical opacity 1−2, and posterior subcapsular opacity 1. She underwent phacoemulsification using a clear corneal approach while under topical anesthesia, and an intraocular lens was successfully implanted in the bag. A plastic syringe with an irrigating needle was used to hydrate the corneal stroma at the clear cornea site. As a result of the increased pressure applied to the connection between the syringe and irrigating needle, the loosened irrigating needle was forcefully ejected toward the corneal endothelium, horizontally penetrating the stroma without injuring the corneal epithelium. On the 1st postoperative day, her right eye exhibited a visual acuity of 0.5, astigmatism of −1.25 diopter (D) cyl., corneal edema with Descemet's folds, and insignificant scarring of the corneal endothelium. Three weeks after surgery, the visual acuity was 0.9, the astigmatism was −0.50 D, and any other abnormalities such as corneal opacity were no longer present. CONCLUSIONS: Despite a penetrating needle injury through the corneal endothelium and stroma, the corneal wound healing process did not result in corneal opacity or worsened astigmatism. To prevent sequela due to an ejected irrigating needle, operators and assistants should be actively aware of tight locking between the needle and syringe.

The role of thrombospondin-1 in corneal wound healing / 中华实验眼科杂志

Thrombospondin-1 (THBS-1),a kind of extracellular matrix proteins,whose biological action played an important role in corneal wound healing has became a research highlight.The currently research findings showed that THBS-1 could promote the healing of epithelium,stroma and endothelium through activating the transforming growth factor-β1 (TGF-β1) which can accelerate cell proliferation,promote stroma forming and inducing cell migration.It is worthful in clinical treatment of all kinds of corneal wound healing.Now we summarized the research developments which have been acquired in the field recently in this article.

Bone Marrow Mesenchymal Stem Cell Transplantation in a Rabbit Corneal Alkali Burn Model (A Histological and Immune Histo-chemical Study)

BACKGROUND: Alkali-burned corneas can seldom heal properly to restore corneal transparency. Treatment of this severe disorder of the ocular surface remains a challenge. AIM OF THE WORK: was to investigate whether systemically transplanted bone marrow mesenchymal stem cells (BM-MSCs) can promote corneal wound healing after alkali burn. MATERIAL AND METHODS: Thirty five male New Zealand rabbits were used in this study. The animals were divided into three groups. Group I; the control group was sham operated. Group II; corneal alkali burn was created. Group III; underwent corneal alkali burn then treated with BM-MSCs. All corneas were collected after fourteen and twenty eight days. Evaluation using H&E, PAS & alkaline phosphatase reaction was carried out. Immune histo-chemical staining for CD44 and vimentin was performed as well. RESULTS: the corneal epithelium of (Group II) showed marked alterations. Vascularization, cellular infiltration and irregularity of the collagen fibers were also seen in the substantia propria. Increase in the thickness of the Descemet's membrane was noticed as well. On the other hand, at the time of 28 days, Group III rabbits showed best histological results with nearly healed corneas compared to other groups. Meanwhile, vimentin was more strongly expressed in Group III assessing the differentiating ability of BM-MSCs. CONCLUSION: BM-MSCs could effectively promote corneal alkali burn healing.

Enlightenment from corneal wound healing for excimer laser refractive surgery / 眼科研究

Wound healing in the human cornea has distinctive characteristics in comparison to most other tissues in the body.The corneal wound healing response is a remarkably complex cascade mediated by cytokines,growth factors,and chemokines.The interactions in the epithelial,stromal,neural,lacrimal gland,immune cells are interwoven in the corneal response to injury.Corneal epithelial cells and basement membrane play important roles in this process.However,both of them are usually impaired during the procedures of excimer laser refractive surgery for myopia,hyperopia,or astigmatism,and complications such as overcorrection,undercorrection,regression,refractive instability,and haze may occur after surgery.A complete corneal wound healing process,the biologic and molecular processes that contribute to the healing response,and anomalies that lead to complications are critical for improving the efficacy and safety of excimer laser refractive surgical procedures.

Postoperative Pain and Epithelial Wound Healing in Epi-LASIK With and Without an Epithelial Sheet Preservation

PURPOSE: To investigate the influence of preservation of an epithelial sheet in Epi-LASIK on postoperative pain and epithelial wound healing time. METHODS: This prospective study included 34 eyes of 17 patients with myopia who received Epi-LASIK. An epithelial flap was created using the epikeratome (Centurion SES, Norwood Abbey EyeCare, Australia). After the stroma was ablated using the MEL 80 (Carl Zeiss Meditec. Germany) excimer laser, the epithelial sheet was replaced on the stromal bed in one randomly selected eye of each patient, and removed in the contralateral eye. The pain scores at postoperative day 0, 1, 2, 5 and the numbers of days for the complete epithelial wound healing were compared between the sheet-preserved and the sheet-removed eyes. At 1 month postoperative, uncorrected visual acuity (UCVA), refractive error and corneal haze were also compared. RESULTS: Pain scores on the day of operation were lower in sheet-preserved group and statistically significant (p=0.01). On postoperative day 1, 2, and 5, pain scores did not reach statistical significance (p=0.24, 0.08, 0.56, respectively). The mean epithelial healing time was 4.88+/-0.93 days for the flap-preserved eyes and 4.29+/-0.77 days for the flap-removed eyes, which showed statistical significance (p=0.01). No significant difference was noted between the 2 groups for mean UCVA, corneal haze and refractive error at 1 month postoperative. CONCLUSIONS: A preserved epithelial sheet reduced early postoperative pain but did not accelerate epithelial wound-healing rate.

Corneal Epithelial Wound Healing After Treatment with Gatifloxacin with or Without Benzalkonium Chloride in Rabbits

PURPOSE: This study was performed to compare the effect of fourth-generation fluoroquinolones gatifloxacin on epithelial healing and penetration into the aqueous humor following corneal epithelial removal. The administered drugs were Zymar(TM) and Gatiflo(R), which differ from each other by the presence of benzalkonium chloride. METHODS: Eighteen eyes of nine New Zealand white rabbits were randomized to receive either Zymar(TM) or Gatiflo(R) following anterior keratectomy with a diameter of 6.0 mm. Eyes were dosed with either antibiotic according to Food and Drug Administration (FDA) approval; specifically, Zymar(TM) and Gatiflo(R) were dosed every two hours for the first two days and then four times daily for the following five days. Starting from postoperative day 0, photos were taken daily to measure the area of the residual epithelial defects. Anterior chamber paracentesis was performed to determine the drug concentration at postoperative days 1, 2, and 7. RESULTS: The mean healing times after Zymar(TM) and Gatiflo(R) treatment were 3.0+/-0.71 and 3.2+/-0.84 days, respectively (P=0.813). No statistically significant differences in the mean healing time and the mean area of the healed corneal wound were noted between the two groups. No difference in anterior chamber concentration was observed between the two groups at postoperative day 7 (P=0.362). CONCLUSIONS: Although the two drugs differ in that on drug has preservatives, no significant differences were found in the epithelial healing effect or anterior chamber concentration after short-term dosing for 1 week in this trial.

Research progress in signal pathway of corneal wound healing in diabetes mellitus patients / 基础医学与临床

Delayed wound healing of diabetic cornea may be associated with the activation of MAPK signal pathway,impaired signal transduction of TGF-? signal pathway,abnormal expression of genes related to insulin signal pathway and reduced expression of insulin receptor.In addition,the activation of NF-?b and cytochrome C signal pathway also has harmful influence on delayed wound healing.This paper reviews research progress about signal pathway of delayed wound healing in diabetic cornea.

Expression of IRFs and iNOS in the Mouse Cornea with Pseudomonas Aeruginosa Keratitis

PURPOSE: To investigate the expression of IRF-1, IRF-7 and iNOS in the mice model of Pseudomonas aeruginosa keratitis. The enzymatic activity of iNOS and its expression were also investigated. METHODS: With western blot analysis, the protein expression of IRF-1, IRF-7 (at 24 hours), and iNOS (at 12 hours and 24 hours) were evaluated in the mouse model of P. aeruginosa keratitis. iNOS enzymatic activity was determined with a scintillation counter. IRF-1 and IRF-7 expression were localized with immunofluorescent labeling. The wounded control group was given the same corneal wound without bacterial inoculation, and the fellow eyes served as normal controls. RESULTS: Expression of IRF-1, IRF-7 and iNOS was highly upregulated in corneas with P. aeruginosa keratitis compared to normal or wounded corneas. iNOS enzymatic activity also was higher in infected than normal corneas. In wounded corneas, NOS2 expression and activity slightly increased at 12 hours after the infection. Intense IRF-1 immunopositivity was seen in the epithelial layer of infected corneas. Some corneal stromal cells and endothelial cells showed moderate positive labeling in infected corneas. IRF-7 showed intense labeling in the epithelial layer and endothelial cells of normal as well as infected corneas. Increased IRF-7 labeling was observed in epithelial cells in the ulcerated region of infected corneas. CONCLUSIONS: These results suggest that IRF-1, IRF-7 and iNOS may play a regulatory role in the immune responses and wound healing process in P. aeruginosa keratitis.

Immunohistochemical Changes of Rabbit Cornea After Excimer Laser Surface Ablation: collagen type III, IV, VI, VII

We performed photorefractive keratectomy(PRK) on 10 rabbit eyes and determined the distribution of collagen type III, IV VI, VII at postoperative 2, 4 and 6 months to examine immunohistochemical changes after PRK. Type III collagen was not found in the normal cornea but strongly detected in the regenerated corneal stroma at all intervals. It was most prominent at 2 months after surgery and then decreased. Type IV collagen was detected in basement membrane in both normal and ablated corneas at all intervals and the staining was more intense in ablatd corneas than in normal cornea. There was no difference of staining intensity among the groups of different intervals. Type IV collagen was found in both normal and healed corneal stroma at all intervals and there was no difference of staining intensity between normal and ablated corneas and among the groups of different intervals. Type VII collagen was observed as a linear continuous band along the basal surface of epithelium in normal cornea. At 2 months after surgery, type VII collagen staining in basement membrane zone became denser than normal cornea, but segmented. At 4 months after surgery, continuous band of collagen type VII staining was observed, but it was less intense than in normal cornea. At 6 months after surgery, the intensity of continuous band of collagen type VII was the same as in normal cornea. This results suggest that the presence of type III collagen in the regenerated cornea may be related to the development of postoperative subepithelial opacity after PRK and the normalization of collagen type IV and VII at postoperative 6 months may mean the complete reestablished of the adhesion of regenerated epithelium and stroma.

The Effect of Topical Prostaglandin Synthesis Inhibitor and Therapeutic Contact Lens on the Pain and Corneal Reepithelialization after Excimer Laser PRK

In order to evaluate the effect of topical prostaglanduin synthesis inhibitor(Diclod) and therapeutic contact lens(T-lens) on pain control and epithelial wound healing following excimer laser photorefractive keratectomy(PRK) we examined the score of subjective pain & the degree of corneal epithelial defect on 40 consecutive patients with or without above treatment. The patients were subdivided into 4 groups : 10 patients treated with only pressure patch(Group 1), 10 patients with pressure patch & Diclod(Group 2), 10 patients with only T-lens(Group 3), and 10 patients with T-lens & Diclod(Group 4). Diclod(Group 2&4) was effective on pain control during three days after excimer laser PRK, while T-lens treatment was not effective. Subjective pain score between the patient with Diclod(Group 2&4) and those without Diclod(Group 1&3) was significantly different(p< 0.05). In the point of epithelial wound healing after excimer laser PRK, 95% of patients treated with T-lens(Group 3&4) revealed no epithelial defect three days after excimer laser PRK, while only 65% of the patients treated with pressure patch revealed that. The difference was statistially significant(p< 0.05). Diclod, however, did not influence the epithelial wound healing in both pressure group and T-lens group. In this study we could find that the combination of Diclod & T-lens was a recommendable method to decrease the pain & to increase the epithelial wound healing after excimer laser PRK.

The Changes of Marginal Epithelial Cells in Corneal Wound Healing

The changes of marginal epithelial cells in corneal wound healing were observed in a rabbit. The randomly assigned three eyes in the rabbits were extracted at first, third, and eighteenth day after full thickness epithelial removal, then observed under the electronmicroscope. At the 1st and 3rd day ,the thickness of the epithelium at the wound margin was reduced at the leading edge. These flattened epithelial cells showed ruffling and folding of the plasma membrane near free edge to form filopodia or lamellipodia processes, extending onto wound surface. Cytoskeletons reorganized and rearranged in leading edge. Basement membrane of the wound was relatively intact, but on which cellular debris were observed, and cell migration undergone and hemidesmosomes developed incompletely. In eighteenth day, basal cell recovered original cylindric shape, cytoskeletons was originally redistributed in cytoplasm after migratory phase, and hemidesmosome developed completely.

Corneal wound Healing Following Excimer Laser Photorefractive Keratectomy Using Pressure Patch, T-lens and Collagen Shield on Rabbit Cornea

We studied the healing course and histologic change of ablated rabbit cornea following excimer laser photorefractive keratectomy using three different corneal wound healing methods; pressure patch, T-lens, collagen shield. Nine rabbits(18 eyes) were divided into three different groups according to its treatment method. Corneal status including the corneal haze, conjunctival injection, discharge amount at postoperative 1st day, 2nd day and 3rd day were the same, irrespective to the treatment method and corneal wound healing rate show no significant differentces in all the groups. The histologic feature revealed irregular epithelial hyperplasia and keratacyte infiltration in the superficial stromal layer on postoperative 3rd day and 7th day. These reactions lessened at postoperative 1 month. The cornea treated with pressure patch group revealed more severe tissue reaction when compared with the other groups, T-lens and collagen shield. These results suggest that the corneal wounds produced by excimer laser can be managed by T-lens as an another alternative method of wound treatment.