Diagnosis is based on the clinical characteristics and careful funduscopic examination. Fluorescein angiography is a most helpful tool in making diagnosis. Ancillary testing, ultrasound, computed tomography and optical coherence tomography can be used for further evaluation.

Staging classification applicable to diagnosis, treatment and ocular prognosis has been proposed: Stage 1: Retinal telangiectasia only; Stage 2: Telangiectasia and exudation A. Extrafoveal exudation B. Foveal exudation; Stage 3: Exudative retinal detachment A. Subtotal detachment 1. Extrafoveal 2. Foveal B. Total retinal detachment; Stage 4: Total retinal detachment and glaucoma; Stage 5: Advanced end-stage disease approaching phthisis.

Differential diagnosis

Differential diagnosis may vary depending on the stage at presentation. The most important differential diagnosis is unilateral retinoblastoma, which occurs in the same age group and has some overlapping ophthalmoscopic and clinical manifestations.

Other differential diagnoses include Norrie disease, FEVR, ROP, persistent hyperplastic primary vitreous (PHPV), retinal capillary hemangioma, retinal cavernous hemangioma, incontinentia pigmenti, idiopathic juxtafoveal telangiectasis, and toxocariasis.