Two identical twin sisters in their teens presented to the Inherited Retinal Degenerations Clinic at the Wilmer Eye Institute for evaluation of cystoid macular edema (CME), which had been treated intermittently with topical carbonic anhydrase inhibitors. Both girls were myopic from early childhood but denied any visual complaints such as night blindness or visual field constriction, and their family history was negative for retinal diseases or consanguinity.
On her initial visit, twin 1 had best-corrected visual acuity of 20/40 OU; intraocular pressure, confrontational visual fields, pupillary reactions, and anterior segments were normal. Her dilated fundus examination revealed CME and mild mottling of the foveal retinal pigment epithelium in both eyes, but otherwise findings were unremarkable. Optical coherence tomography demonstrated foveal cystoid abnormalities in the inner and outer retina with secondary mild retinal thickening, coarse retinal lamination, and scattered central ellipsoid zone defects in both eyes. Fluorescein angiography did not reveal any leakage or any additional pathological finding in either eye. Autofluorescence imaging demonstrated a petaloid-like pattern of autofluorescence signals in the fovea and a ring of increased autofluorescence signals in the posterior pole (Figure 1).