Two families with Best's vitelliform macular dystrophy (BVMD) were inv
estigated ophthalmoscopically and electrophysiologically. Pedigree exa
mination confirmed the autosomal dominant heredity of this disorder wi
th variable expressivity. Extrafoveal vitelline deposits were present
in some asymptomatic patients, strongly suggesting that these deposits
represent variable expressivity of familial BVMD.