Stargardt disease 

Stargardt disease (STGD) is the most common childhood recessively inherited macular dystrophy. The condition has a genetic basis due to mutations in the ABCA4 gene, that encodes a retinal transported protein; it results from the accumulation of visual cycle kinetics-derived byproducts in the retinal pigmented epithelium (RPE) with secondary photoreceptor dysfunction and death.
Patients typically present with decreased central vision that may be out of proportion to the clinical findings, especially in early stages of the disease. Other symptoms include photophobia and prolonged dark adaptation.
Fundus examination may be normal in early stages. As the disease progresses there may be nonspecific macular mottling progressing to oval snail slime or beaten bronze appearance with subsequent geographic atrophy that tends to a bull's eye appearance. There are pisciform deep retinal flecks located at the posterior pole and extending to mid-periphery. New lesions appear as the older ones become atrophic.
OCT and fundus autofluorescence demonstrate the retinal flecks. Visual fields show loss of central vision. ERG is normal to subnormal and EOG is subnormal. Fluorescein angiography shows characteristic dark choroid due to masking of background choroidal fluorescence by diseased RPE. Macula shows mixed hyper and hypofluorescence. Fresh retinal flecks show early hypofluorescence and late staining and old flecks show window defects.
Clinical trials of stem cell- derived RPE replacement are currently under way for patients with advanced RPE and photoreceptor loss. Gene therapy is also in trial for patients with better preserved retinal architecture. Lastly, modified (deuterated) vitamin A preparations are also being trialled, aiming to reduce the accumulation of toxic bis- retinoids.