Foveal sparing in Stargardt disease

Abstract

Purpose: To provide a clinical and genetic description of a patient cohort with Stargardt disease (STGD1) with identifiable foveal sparing.

Methods: Patients with retinal atrophy (defined as an absence of autofluorescence) that surrounded the fovea by at least 180° and did not include the fovea were defined as having foveal sparing; eyes with visual acuity (VA) worse than 20/200 were excluded. We reviewed the medical files and extracted data regarding medical history, VA, ophthalmoscopy, static perimetry, fundus photography, spectral-domain optical coherence tomography (SD-OCT), fluorescein angiography (FA), fundus autofluorescence (FAF), and electroretinography (ERG). We screened each patient's ABCA4 gene for mutations.

Results: Seventeen eyes with foveal sparing were identified in 13 unrelated patients. In 4 eyes, the fovea gradually became atrophic after the initial foveal sparing. The mean age at onset was 51 years (range, 32-67 years). Visual acuity was 20/40 or better in all foveal sparing eyes and was 20/25 or better in 41%. Fundus autofluorescence imaging revealed hyperautofluorescent flecks and parafoveal retinal atrophy; SD-OCT revealed sharply delineated atrophy; and perimetry revealed parafoveal scotomas with intact foveal sensitivity. Finally, genetic screening identified mutations in 19 of the 26 ABCA4 gene alleles.

Conclusions: Foveal sparing occurs mainly in patients with late-onset STGD1 and represents the milder end of the clinical spectrum in STGD1. The anatomy, metabolism, and biochemistry of the retina, as well as genetic variations in genes other than ABCA4, can influence the etiology of foveal sparing. Identifying these fovea-protecting factors will facilitate the future development of strategies designed to treat STGD1.

Keywords: ABCA4; Stargardt disease; foveal sparing.