The purpose of this study is to establish the natural history of of participants with BESTROPHIN 1 Vitelliform Macular Dystrophy. The blinding disorder Best Vitelliform Macular Dystrophy (VMD) is caused by any one of more than 250 different mutations in the BEST1 gene. As new treatments are developed, a clear understanding of the natural history of disease progression of BEST1 VMD is necessary. The goals of this natural history study are to: 1. Report the natural history of retinal degeneration in participants with a clinical diagnosis of VMD with molecular confirmation of a pathogenic BEST1 mutation(s). 2. Identify sensitive structural and functional outcome measures to use for future multicenter clinical trials for the treatment of BESTROPHIN 1 VMD. 3. Compare progression of the identified structural and functional measures between the two eyes to judge the suitability of the second untreated eye as a control for a future clinical trial involving unilateral treatment 4. Identify well-defined patient populations for future clinical trials of investigative treatments for BEST1 VMD.