Abstract
Purpose: :
To investigate the prevalence of a peripapillary "dark choroid ring" (PDCR) on fluorescein angiography (FA) in patients with Stargardt disease.
Methods: :
Retrospective analysis of FA images of 85 patients diagnosed with Stargardt disease by either a) two causative mutations detected in the ABCA4 gene, or b) one causative mutation and the presence of at least one of following clinical features; fundus flecks, central retinal atrophy, or a dark choroid on FA, or c) a clinical diagnosis made by the combined presence of fundus flecks and a dark choroid on FA, with mutational analysis pending.
Results: :
The ring was apparent in more advanced cases in which the posterior pole had damaged RPE that showed staining and loss of the dark choroid effect. A total of 33/85 (39%) of the patients had a PDCR on FA. A PDCR was found in 6/22 (27%) of the patients with 2 causative mutations, 5/17 (29%) of the patients with 1 causative mutation, and 22/46 (48%) of patients with pending mutational analysis. The sign manifested only in patients with extensive hyperfluorescent posterior pole flecks on FA, which obscure the dark choroid effect.
Conclusions: :
The presence of a PDCR on FA should prompt further investigation for Stargardt disease by 1) determining the presence of a dark choroid effect in peripheral retinal FA images, and 2) subsequent ABCA4 mutation screening. The intracellular retinal pigment epithelial (RPE) lipofuscin accumulation causes a dark choroid effect on FA throughout the fundus. Focal areas of RPE cell engorgement with lipofuscin causes the appearance of hyperfluorescent staining flecks on FA due to fluorescein binding, and with time some cases show a diffuse RPE hyperfluorescent staining of the posterior pole obscuring the dark choroid effect. In these patients a PDCR is a helpful finding for making the diagnosis.
Keywords: retinal degenerations: hereditary • imaging/image analysis: clinical