Clinical and Molecular Analysis of Stargardt Disease With Preserved Foveal Structure and Function

PurposeTo describe a cohort of patients with Stargardt disease who show a foveal-sparing phenotype.DesignRetrospective case series.MethodsThe foveal-sparing phenotype was defined as foveal preservation on autofluorescence imaging, despite a retinopathy otherwise consistent with Stargardt disease. Forty such individuals were ascertained and a full ophthalmic examination was undertaken. Following mutation screening of ABCA4, the molecular findings were compared with those of patients with Stargardt disease but no foveal sparing.ResultsThe median age of onset and age at examination of 40 patients with the foveal-sparing phenotype were 43.5 and 46.5 years. The median logMAR visual acuity was 0.18. Twenty-two patients (22/40, 55%) had patchy parafoveal atrophy and flecks; 8 (20%) had numerous flecks at the posterior pole without atrophy; 7 (17.5%) had mottled retinal pigment epithelial changes; 2 (5%) had multiple atrophic lesions, extending beyond the arcades; and 1 (2.5%) had a bull's-eye appearance. The median central foveal thickness assessed with spectral-domain optical coherence tomographic images was 183.0 μm (n = 33), with outer retinal tubulation observed in 15 (45%). Twenty-two of 33 subjects (67%) had electrophysiological evidence of macular dysfunction without generalized retinal dysfunction. Disease-causing variants were found in 31 patients (31/40, 78%). There was a higher prevalence of the variant p.Arg2030Gln in the cohort with foveal sparing compared to the group with foveal atrophy (6.45% vs 1.07%).ConclusionsThe distinct clinical and molecular characteristics of patients with the foveal-sparing phenotype are described. The presence of 2 distinct phenotypes of Stargardt disease (foveal sparing and foveal atrophy) suggests that there may be more than 1 disease mechanism in ABCA4 retinopathy.