Objective: We investigated the mechanism of drug-induced transient myopia, anterior chamber shallowing, and secondary angle-closure glaucoma in a young woman.

Methods: Ultrasound biomicroscopy was performed and the effects of cycloplegic eyedrops and unilateral laser iridotomy were evaluated.

Results: Cycloplegic eyedrops and unilateral laser iridotomy had no effect. Ultrasound biomicroscopy identified the presence of a supraciliary choroidal effusion that caused forward displacement of the lens-iris diaphragm, resulting in increased myopia, anterior chamber shallowing, and angle-closure glaucoma. Discontinuance of trimethoprim and sulfamethoxazole combination led to the complete resolution of the condition.

Conclusions: Idiosyncratic drug reactions may produce a supraciliary choroidal effusion, resulting in myopia and secondary angle-closure glaucoma from the induced forward shift in the position of the crystalline lens and ciliary body.