The Therapeutic Approach and Mechanism of Action of Insulin Eye Drops for the Treatment of Neurotrophic Keratitis

Abstract: Neurotrophic keratopathy or keratitis (NK) is a degenerative corneal disorder characterised by reduced corneal sensitivity and impaired epithelial repair, most often associated with trigeminal nerve dysfunction. Topical insulin eye drops have been proposed as a potential adjunctive therapy, but wider clinical adoption is constrained by variability in preparation methods, inconsistent dosing approaches, and the absence of consensus guidance or regulatory approval. Current clinical experience suggests that topical insulin may be well tolerated and could offer therapeutic value in selected NK settings, including difficult-to-manage cases. Nonetheless, the overall evidence base remains limited and heterogeneous, making it challenging to define optimal regimens or confidently position topical insulin within existing treatment pathways. This review includes clinical studies and case reports and highlights the role of TI as a promising, cost-effective and well-tolerated treatment option for neurotrophic keratopathy, especially in refractory cases. This work also illustrates the need for further research to standardise formulation and dosing, establish practical clinical guidance, and clarify the patient populations and disease stages most likely to benefit, as well as the role of topical insulin alongside established interventions. Keywords: insulin eye drops, neurotrophic keratitis, topical insulin, persistent epithelial defects, corneal healing, cornea