Cystoid Macular Edema Due to Accidental Latanoprost Overdose After Uncomplicated Phacoemulsification

Objective: We present an interesting case of accidental overdose of latanoprost eye drops. Case Report: A 71-year-old patient underwent an uncomplicated cataract surgery in his right eye. During the first postsurgical week he mistakenly used latanoprost eye drops six times daily instead of the prescribed tobramycin/dexamethasone eye drops. The patient experienced gradually decreasing visual acuity and was diagnosed with cystoid macular edema seven weeks after surgery. The cystoid macular edema resolved 4 weeks later after treatment with nepafenac 0.3% eye drops and oral acetazolamide. The cystoid macular edema recurred 2 weeks after rechallenge with latanoprost. The rechallenge-induced cystoid macular edema once again resolved after cessation of latanoprost and retreatment with nepafenac eye drops. A Naranjo assessment score of 7 was obtained, indicating a probable relationship between the patient's symptoms and the suspect drug.