Toxic Keratopathy Associated with Abuse of Topical Anesthetics

Abstract

Introduction: Topical corneal anesthetics abuse is a self-inflicted injury. Prolonged and uncontrolled uses of topical anesthetics have a significant probability of leading to various complications as a result of the morphological changes they induce in the corneal structure. Topical anesthetics compromise tear function by decreasing aqueous tear secretion, disturbing film stability and decreasing blink rate which leads to greater exposure of the cornea to outside factors, thus decreasing the protective function of the corneal epithelial cells. As a result, both the corneal epithelial barrier and the re-epithelialization process are disrupted, which is the main factor in the pathogenesis of the toxic keratopathy. The most prescribed topical anesthetics in practice are tetracaine, proparacaine and oxybuprocaine. All of the above-mentioned drugs have been described as abusive and addicting medications. Loss of vision, intense pain, severe photophobia and red eye are the most frequently reported symptoms by patients. Materials and Methods: Medical records of four patients were used for the purpose of this poster. The severe pain, persistent epithelial defects and progressing stromal thinning that were found during the initial examination did not improve with medical treatment, thus, the patients underwent amniotic membrane transplantation (AMT) and cross-linking. Results: After the treatment, the symptoms of photophobia and pain were relieved. A complete corneal epithelialization and total reduction of the corneal infiltrate were ascertained in a period of 2 weeks. Conclusion: Topical anesthetic abuse can lead to serious ocular complications. After proper diagnosis, the first step of treatment is the cessation of drug abuse. In addition to medical treatment, early AMT and cross-linking has an advantage of early pain relief and consequential elimination of the need for topical anesthetic application.