To report a case of cataract after long-term use of clonazepam in a young patient, with a similar appearance to cataract induced by other psychotropic agents.

A 37-year-old woman complained of a visual disturbance in both eyes. The best-corrected visual acuity was 0.8 in the right eye and 0.6 in the left eye. Bilateral cortical cataract was observed on slit-lamp examination, and no other ophthalmic abnormalities were found. Potential risk factors for cataract were investigated, including past medical and family history, revealing a 20-year history of oral clonazepam (0.5-1 mg/day), for the neurological diagnosis of "chorea of unknown etiology". Detailed medication history did not reveal long-term use of any other drugs which could have induced the cataract.

Because clonazepam use may induce cortical cataract, regular ophthalmologic examinations are necessary during long-term oral psychotropic therapy.