Vitreoretinal toxicity of acetazolamide following intravitreal administration in the rabbit eye

Acetazolamide, a carbonic anhydrase inhibitor, has been shown effective in the treatment of cystoid macular edema; however, chronic use of the drug is limited by its serious systemic side effects. Intraocular administration can eliminate these systemic complications. We evaluated vitreoretinal toxicity after intravitreal injection of acetazolamide in the rabbit eye. The right eye of each rabbit received a single acetzolamide injection; the left eye received balanced salt solution and served as a control. The effect of the drug was evaluated by clinical observation, electroretinography, and histopathologic study. Intravitreal injection of up to 0.5 mg acetazolamide did not cause vitreoretinal toxicity. Injection of 1 mg or higher doses depressed the b-wave amplitude of electroretinograms and damaged the outer segments of the photoreceptors, as determined by light and electron microscopy.