Optical Coherence Tomography Examination of the Retinal Pigment Epithelium in Best Vitelliform Macular Dystrophy.

PURPOSE: To describe the anatomic changes and natural history of vitelliform lesions in Best vitelliform macular dystrophy (BVMD) using spectral-domain optical coherence tomography (OCT). DESIGN: Prospective comparative case series. PARTICIPANTS: Twenty patients (40 eyes) with molecular confirmation of mutation in the BEST1 gene and 20 age-matched controls were included. METHODS: Color fundus photographs, fundus autofluorescence, and spectral-domain OCT were obtained, and these findings were compared between the 2 groups. Fifteen of the 20 patients with Best disease had more than 1 visit, and the imaging studies from each visit were compared with each other over time. MAIN OUTCOME MEASURES: Evolution of visual acuity and clinical stage of BVMD correlated to OCT measurement parameters, including retinal pigment epithelium (RPE) thickness, central macular thickness, and integrity of the ellipsoid zone. RESULTS: Patients with BVMD demonstrated progressive disorganization and thinning of the submacular RPE on OCT when compared with normal controls. Concurrent with the appearance of "egg-yolk lesions," the OCT showed a cleft in the outer retina, creating an apical and basal separation of retinal layers. The apical complex of the vitelliform lesion eventually degenerated and flattened. Patients with such lesions nevertheless maintained reasonable visual acuity into the advanced vitelleruptive stages despite the disruption of normal anatomic changes. CONCLUSIONS: Our study suggests that in BVMD, subretinal vitelliform material accumulation leads to a clear separation of the outer retinal layers. The level at which this cleft forms is a topic of discussion and interest, with the most likely levels of least resistance being the interdigitation zone or between the RPE and the Bruch's membrane. It is possible that RPE may continue to form a preserved photoreceptor-RPE complex that provides essential nutrients to the photoreceptors and in turn helps patients maintain better than expected visual acuity for years.