Cocaine snorting may induce ocular surface damage through corneal sensitivity impairment

Purpose: Cocaine abuse may cause severe ischemic and necrotic tissue damage in several organs, including the eye. However, the cornea is an avascular tissue relying on sensitive nerves for its trophic support, and the pathogenesis of cocaine-induced corneal lesions is unclear. In this study, we aimed to investigate if corneal sensitivity, ocular surface, and tear function are damaged by habitual cocaine snorting. Methods: Ocular examination, corneal sensitivity, and tear function testing were carried out in 48 cocaine addicts, and in 22 heroin addicts and 30 drug-free age/sex-matched individuals who served as controls. We also performed corneal confocal microscopy, conjunctival impression cytology, and tear sample collection to evaluate corneal and conjunctival morphology, and the presence of cocaine in tears. Statistical analysis was performed to compare groups and to correlate clinical findings with anamnestic data on cocaine use. Results: We observed decreased corneal sensitivity in 26 cocaine addicts, and neurotrophic keratitis in six of them, with corneal damage, absence of symptoms, reduced tear production, and prolonged interblink-time. No significant changes in ocular surface parameters including corneal sensitivity were observed in heroin addicts. The major risk factors for developing cocaine-induced neurotrophic keratitis appeared to be duration and frequency of drug abuse. Conclusions: A complete ophthalmic evaluation including corneal sensitivity testing should be planned for an optimal management of cocaine addicts, even in the absence of ocular symptoms, to reduce the risk of corneal lesions and consequent vision impairment. Sensory nerve damage should also be evaluated in cocaine-induced lesions of other organs.