Ethambutol-induced optic neuritis in patients with end stage renal disease on hemodialysis: two case reports and literature review.

Ethambutol, a synthetic bacteriostatic agent, is a first line agent against Mycobacterium tuberculosis. Although optic neuritis is the most serious adverse effect of ethambutol, most cases in the literature are reversible. Renal failure prolongs the half-life of ethambutol and increases the risk of ethambutol-induced optic neuritis. We present two patients with end stage renal disease (ESRD), who were on maintenance dialysis and suffering ethambutol-induced optic neuritis. The first woman had been suffering ESRD on hemodialysis for 2 years. After tuberculosis was diagnosed, she was prescribed three-combined anti-tuberculosis medications, including ethambutol 800 mg/day. Bilateral blurred vision suddenly occurred 4 months after the start of treatment, and she became totally blind despite discontinuing ethambutol. The second woman had been on hemodialysis for 5 months. Tuberculosis was diagnosed by lung biopsy. After 3 weeks of three-combined anti-tuberculosis medications including ethambutol (1,200 mg/day), reduced visual acuity and color vision defects occurred. One year after the discontinuation of ethambutol, visual acuity remained little improved. Physicians should be aware of ethambutol-induced optic neuritis and ethambutol should be used cautiously in patients with renal failure.