Phenotypic subtypes of Stargardt macular dystrophy-fundus flavimaculatus

Objective: To determine if phenotypic subtypes exist in Stargardt macular d ystrophy-fundus flavimaculatus (SMD-FFM). Methods: A cross-sectional study of 63 patients with autosomal recessive SM D-FFM was undertaken. The age of onset, duration of symptoms, visual acuity , and clinical features on fundus examination, color fundus photographs, an d fundus autofluorescence images were recorded. Electrophysiological tests, including pattern, focal, and fullfield electroretinogram (ERG), electro-o culogram, and color-contrast sensitivity measurement, were also performed. Results: Based on electrophysiological attributes (ERG), patients with SMD- FFM could be classified into 3 groups. In group 1, there was severe pattern ERG abnormality with normal scotopic and full-field ERGs. In group 2, ther e was additional loss of photopic function, and in group 3, there was loss of both photopic and scotopic function. Differences in scotopic or photopic function among groups were not explained on the basis of differences in ag e of onset or duration of disease. Conclusions: Patients with SMD-FFM can be classified into 3 groups based on the absence or presence of generalized loss of either photopic or photopic and scotopic function. It appears that these 3 groups may represent distin ct phenotypic subtypes in SMD-FFM.