Topical insulin treatment efficacy in rat corneal epithelial wound healing model and comparison of efficacy with topical hyaluronate treatment

This study aimed to examine the effect of topical insulin on healing of the corneal epithelium in a rat corneal epithelial defect model, comparing it to artificial tears and non-treated controls. 28 adult male Sprague Dawley rats were divided into 4 groups in this study. A 2 mm diameter epithelial defect was created at the central cornea of one eye under sedation. Group A had untreated epithelial defects, Group B received 0.15 % sodium hyaluronate qid, and Group C received topical 1IU/mL insulin qid. The last group was healthy controls. Biomicroscopic examinations were performed at the 4th hour, 12th hour, 1st day, 2nd day, and 3rd day0. The defect size of epithelium was photographed during each examination using fluorescein staining. The area of the defect was calculated using the ImageJ software to determine the percentage of defect closure. On the 10th day, corneal tissues were excised for histopathological examination, after sacrification. Topical insulin and sodium hyaluronate treatment groups showed faster healing rate of corneal epithelial defect closure biomicroscopically compared to the untreated group. However, there was no statistically significant difference in the rate of epithelial defect closure between topical insulin and sodium hyaluronate groups. Histopathologically, topical insulin group showed superior epithelial remodeling at the fine structural level. Although no biomicroscopic difference was observed in corneal epithelial healing with topical insulin treatment compared to sodium hyaluronate, it has been demonstrated to be more effective histopathologically.