Topical Insulin for Neurotrophic-Related Epithelial Defects: Where do We Stand? A Systematic Review

Purpose To review the existing literature to evaluate the utility of insulin eye drops as a treatment for neurotrophic-related epithelial defects. Methods A comprehensive literature search of Medline, Embase, and Web of Science and additional manual searches were conducted using relevant keywords. All articles published from January 2005 to January 2024 were examined. Studies on the use of topical insulin drops in neurotrophic epithelial defects were included. Results A total of 16 articles were found relevant to be discussed in the review. All included patients had neurotrophic-related epithelial defects ranging from 3.8 mm2 to 144 mm2. After treatment with topical insulin, most of the epithelial defects showed a complete epithelialization. Various concentrations and types of insulin were used. The studies also varied in the type of vehicle used in the preparation of insulin drops. Two randomized controlled trials demonstrated that topical insulin drops were more effective than conventional treatment with artificial tears or autologous serum. All included studies, except for two, reported the absence of local or systemic side effects. Conclusions Topical insulin is a promising and effective (adjuvant) treatment for neurotrophic keratopathy. It facilitates the healing of neurotrophic epithelial defects and offers many advantages over the current treatment options; insulin is widely available and it is relatively inexpensive. Topical insulin drops do not affect systemic blood glucose levels and are well tolerated. However, further investigation is needed.