Toxicities of topical ophthalmic anesthetics

Topical ocular anesthesia has been part of ophthalmology for more than a century. The most commonly used drugs today are proparacaine, tetracaine, benoxinate (oxybuprocaine) cocaine and lidocaine. Although generally well tolerated, all these can be toxic, particularly when abused. The most common toxicities are to the ocular surface, but abuse can cause deep corneal infiltrates, ulceration and even perforation. Fortunately, systemic side effects are rare. Cocaine is unique for its higher incidence of systemic side effects and high abuse potential, both of which impede its clinical use. When used appropriately, all these drugs are remarkably safe. They are generally not prescribed for home use, as prolonged abuse of these drugs can be expected to result in serious complications.