Background and Objective: Choroidal thickness (CT) measurements from eyes with similar areas of macular geographic atrophy (GA) secondary to age-related macular degeneration (AMD) and Stargardt disease (STGD) were compared to determine whether GA from different diseases had a similar or different effect on the underlying subfoveal choroid. Patients and Methods: Eyes with the diagnosis of central GA secondary to STGD and AMD were matched, with subfoveal CT measurements obtained from the central B-scan using an enhanced depth imaging protocol. The area of GA was measured using fundus autofluorescence (FAF) imaging. AMD eyes were divided into those with and without reticular pseudodrusen. Results: A total of 22 eyes of 22 patients were included in the STGD and AMD groups and were matched with respect to the area of GA. The mean age of the STGD patients was 48.9 years (standard deviation [SD] = 17.1), and the mean age was 81.8 years (SD = 6.2) for the AMD patients. Mean area measurements of GA for the STGD and AMD groups were 5.4 mm2 (SD = 4.1) and 5.1 mm2 (SD = 4.0), respectively (P = .83). After adjusting for age and axial length, eyes with STGD had a mean CT measurement greater than the AMD eyes (336.1 μm vs. 198.1 μm, respectively; P = .039). However, this difference was driven by AMD eyes with reticular pseudodrusen (RPD) and by a single Stargardt case with a very thick choroid. Eyes with RPD had statistically thinner subfoveal CT measurements when compared with all other groups. Conclusion: A small but statistically significant increase in the CT of STGD eyes was observed when compared with normal controls and AMD eyes without RPD. However, this small increase in CT was driven by a single case with a markedly thicker choroid within the STGD group, so it is unlikely that a clinically significant difference exists. However, AMD eyes with GA and RPD had significantly thinner subfoveal CT measurements.
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