Objective: To describe the anatomical phenotypes of Best vitelliform macular dystrophy (BVMD) with spectral-domain optical coherence tomography (SD-OCT) in a large series of patients with confirmed mutations in the BEST1 gene.
Methods: In our retrospective observational case series, we assessed 15 patients (30 eyes) with a clinical diagnosis of vitelliform macular dystrophy who were found to have mutations in the BEST1 gene. Color fundus photographs and SD-OCT images were evaluated and compared with those of 15 age-matched controls (30 eyes). Using a validated 3-dimensional SD-OCT segmentation algorithm, we calculated the equivalent thickness of photoreceptors and the equivalent thickness of the retinal pigment epithelium for each patient. The photoreceptor equivalent thickness and the retinal pigment epithelium (RPE) equivalent thickness were compared in all patients, in a region of the macula outside the central lesion for patients with BVMD and outside the fovea in control patients. Paired t tests were used for statistical analysis.
Results: The SD-OCT findings revealed that the vitelliform lesion consists of material above the RPE and below the outer segment tips. Additionally, drusen-like deposition of sub-RPE material was notable, and several patients exhibited a sub-RPE fibrotic nodule. Patients with BVMD had a mean photoreceptor equivalent thickness of 28.3 μm, and control patients had a mean photoreceptor equivalent thickness of 21.8 μm, a mean difference of 6.5 μm (P < .01), whereas the mean RPE equivalent thickness was not statistically different between patients with BVMD and control patients (P = .53).
Conclusions: The SD-OCT findings suggest that vitelliform material is located in the subretinal space and that BVMD is associated with diffuse photoreceptor outer segment abnormalities overlying a structurally normal RPE.
Clinical relevance: These findings provide new insight into the pathophysiology of BVMD and thus have implications for the development of therapeutic interventions.