Cystoid Macular Edema Secondary to Acute Retinal Necrosis: The Role of Fundus Fluorescein Angiography in Guiding Treatment

Cystoid macular edema (CME) is an uncommon but vision-threatening sequelae of acute retinal necrosis (ARN). We report a patient who developed CME following vitreoretinal surgery for ARN-associated retinal detachment. Multimodal imaging, particularly fundus fluorescein angiography (FFA), revealed diffuse capillary leakage suggestive of persistent retinal vascular inflammation. Initial therapy with topical interferon alpha-2b yielded no anatomical or visual benefit. In contrast, intravitreal sustained-release dexamethasone resulted in rapid resolution of CME and significant visual improvement without reactivation of viral retinitis. This case highlights the potential role of FFA in identifying retinal vascular leakage predictive of treatment response, thereby guiding the treatment. Careful monitoring remains essential given the risk of viral reactivation with intravitreal corticosteroids.