Topical insulin appears to promote reepithelialization in neurotrophic keratitis

The burgeoning field of regenerative medicine has highlighted insulin’s function in encouraging cell growth. With insulin found in the ocular surface and tears, researchers have hypothesized that insulin may induce epithelial healing. This study examines topical insulin and reepithelialization in patients with stage 2 or 3 refractory neurotrophic keratitis.

Study design

This was a retrospective study aimed at evaluating the clinical outcomes of topical insulin therapy for eyes with neurotrophic keratitis that are unresponsive to conventional treatments. The primary outcome was complete reepithelialization of persistent epithelial defects and the secondary outcome was improvement in best-corrected visual acuity (BCVA) post-treatment.

Outcomes

Nineteen of 21 eyes (90%) achieved complete resolution of a persistent epithelial defect within 7 to 45 days of follow-up. Stage 2 cases achieved reepithelialization at a mean of 18 days, which was significantly faster than the mean of 29 days required for stage 3 cases to reepithelialize. BCVA improved significantly in both stage 2 and 3 cases. No side effects of insulin therapy were reported. During follow-up, the epithelial defect recurred in 2 cases after insulin discontinuation. Complete reepithelialization recurred following reinitiation of topical insulin. These 2 patients were kept on a low dose of topical insulin.

Limitations

This study was retrospective in nature, had a small sample size of 21 eyes, and did not compare insulin drops to other treatments for later stage neurotrophic keratitis such as cenegermin, serum tears, or growth factor-enriched plasma.

Clinical significance

Insulin, which can be found on the ocular surface and in tears, can contribute to epithelial healing. Topical insulin drops can potentially serve as an effective therapy in refractory neurotrophic keratitis.