Widefield Retinal Imaging in Gyrate Atrophy: Correlation of Structural, Biochemical, and Functional Characteristics.

Objectives: To profile a cohort of gyrate atrophy patients classified by widefield retinal imaging and correlate the structural, biochemical, and functional characteristics.

Design: Retrospective observational cohort study.

Participants: Sixty-five patients (129 eyes) with gyrate atrophy.

Methods: Data of participants with a diagnosis of gyrate atrophy were retrieved from their electronic medical records (January 2015 to December 2023). Retinal involvement was classified into three zones using widefield retinal images. Zone 3 had atrophic patches in the area anterior to the equator; Zone 2 had involvement limited to the arcades but posterior to the equator; Zone 1 had involvement within the vascular arcades and/or peripapillary region, with or without any other zone involvement. Macular assessment was performed using swept-source OCT (n=104). Flash ERG was performed in 40 eyes. serum ornithine levels (n=35) were measured, and genetic analysis was conducted (n=18).

Main outcome measures: Demography, patient profile, zone of retina involved, macular features, and serum ornithine levels.

Results: The average age at presentation was 26.4 (range: 5-67) years, majority were male. Nyctalopia (n=35, 53.8%) and blurred vision (n=29, 44.6%) were the most common symptoms. Positive family history was reported in 32.3% of patients. Most eyes were myopic (69.8%<-3 D). Posterior subcapsular cataracts were documented in 36.4% of eyes. The highest frequency of retinal area affected was Zone 1 (57.14%), followed by Zone 2 (33.33%) and Zone 3 (9.52%), correlating with age at presentation. Foveoschisis was observed in 57.7% of eyes, with a higher prevalence in eyes with Zone 1 disease. Elevated serum ornithine levels (>163 μmol/L) were found in 77.14% of patients. ERG showed non-recordable (n=32) or severely reduced (n=8) responses in scotopic and photopic phases. Genetic analysis of 18 patients identified mutations in the OAT gene, including a novel missense variant (c.290T>C).

Conclusions: This large cohort of patients with gyrate atrophy revealed symmetrical involvement, predominantly in Zone 1. Most patients presented between the first and third decades, experienced nyctalopia, vision reduction, early posterior subcapsular cataracts, and varying degrees of myopia. Zone 1 involvement was strongly associated with foveoschisis and visual compromise.