Regenerative effects of topical insulin on corneal wound healing: From surface restoration to stromal remodeling.

Abstract

AIM: This study aimed to investigate the regenerative efficacy of topically administered insulin on corneal epithelial and stromal healing in a well-established rabbit model of ocular surface damage induced by chemical injury. METHODS: A standardized alkali burn model was created in the right eyes of 16 New Zealand white rabbits. Animals were randomly assigned into four groups: insulin-treated group (I group, n = 6), polyvinyl alcohol + povidone-treated group (P group, n = 6), untreated control group (C group, n = 4), and uninjured healthy controls (H group, n = 3). RESULTS: No statistically significant differences were observed among experimental groups regarding the epithelial defect area on day 1. By day 3, complete epithelial closure was achieved in all treated groups. There was no major intergroup differences were observed in surface integrity or clarity; in fact, insulin did not enhance epithelial healing or improve clinical scores compared to the control group However, stromal edema persisted more prominently in the insulin and control groups compared to healthy controls. Although α-SMA immunoreactivity did not show a significant intergroup difference, its relative increase in the insulin group may reflect early fibrotic remodeling. Electron microscopy demonstrated more compact and aligned collagen fibrils, as well as a greater density of telocyte-like interstitial cells in the insulin group-suggestive of enhanced stromal restructuring and repair. DISCUSSION: Topical insülin was associated with ultrastructural changes suggestive of stromal remodeling following chemical injury, although histological findings (including marked stromal edema) and the absence of clinical improvement indicate that its effect on overall corneal restoration remains uncertain. The presence of telocyte-like cells and improved collagen fibril organization in the insulin-treated corneas indicates a potential role for insulin in promoting physiological stromal remodeling. These findings support further investigation into insulin-based topical therapies for corneal wound healing.