Abstract
Purpose:
To characterize baseline lesions of atrophy of the retinal pigment epithelium (RPE) from fundus autofluorescence (FAF) images and to estimate the annual rate of atrophy progression in a cohort of patients with Stargardt Macular Dystrophy (STGD).
Methods:
n this prospective longitudinal observational study, 34 eyes of 18 STGD patients were included with a minimum observation period of 5 months. FAF imaging was obtained following a standard operating procedure. For each individual FAF image, atrophic lesions within the ETDRS grid were semi-automatically detected by the RegionFinder (Spectralis®, Heidelberg Engineering) and manually corrected to adjust the borders of atrophy. The automatic numerical output for the number of lesions per image and total area of atrophy were recorded for each individual FAF scan and the annual rate of progression was estimated. The study was approved by the Institutional Review Board.
Results:
83 FAF images were evaluated overall. The mean size of atrophy at baseline (34 FAF images) was 4.0 (SD: 6.60; median: 1.84; range: 0.06-33.45) mm2. The mean number of lesions at baseline was 7.6 (SD: 10.5; median: 5.0; range: 1-64). The mean rate of progression was 0.92 (SD: 0.87; median: 0.67; range: -0.01-3.38) mm2/year as calculated from 49 follow-up FAF images. No association was found between the rate of progression and the number of atrophic areas at baseline (p=0.72). The annual progression rate appeared to be associated with the total atrophic area at baseline: accounting for within eye and within subject correlation, and adjusted for number of atrophic areas in a single scan, the relationship was significant (p = 0.024).
Conclusions:
The mean rate of progression of atrophy of the RPE was found to be similar to a previous study using different analysis tools (Chen et al. Eye Res. 91:143-52). Larger areas of atrophy at baseline appear to be associated with higher progression rates. The RegionFinder offers a time-efficient method for the identification and quantification of atrophic areas on FAF images and allows to estimate progression rates in STGD and thus may prove to be useful for disease monitoring in clinical practice and for the analysis of outcome measures in future clinical trials in STGD.
Keywords: 696 retinal degenerations: hereditary •
550 imaging/image analysis: clinical •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)