A young patient presents with significant loss of central vision and a normal ERG. There is no obvious family history of similar presentation. The most likely diagnosis:

Stargardt's disease is a common autosomal recessive maculopathy of early and young adult onset, characterized by progressive loss of central vision and the appearance of yellowish flecks at the level of the retinal pigment epithelium at the posterior pole. ERG is usually normal but may be reduced with increasing amounts of peripheral flecks & atrophy. EOG is usually subnormal. Ref: Medical Retina: Focus on Retinal Imaging - Page 73; Retina: color atlas and synopsis of clinical ophthalmology - Page 153.