This appearance is difficult to distinguish from other causes of macular degeneration. Visual acuity can deteriorate more markedly at this stage. Hyperopia is common. Best disease is autosomal dominant with variable penetrance. The abnormality is in the RPE, as noted on histopathology and electrophysiology testing.
Fluorescein angiogram reveals blockage of choroidal fluorescence by the vitelliform lesion.
The angiogram is otherwise normal at this stage. In the atrophic stage, a transmission defect is noted. If a choroidal neovascular membrane develops, then a corresponding area of hyperfluorescence with leakage will be found. Fundus photography is useful for documentation and follow-up of fundus lesions. The EOG, which reflects RPE function, is the most diagnostic test for evaluating vitelliform macular dystrophy.