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Cindy Cai, Jacob G Light, James T Handa; Quantifying the rate of ellipsoid zone loss in Stargardt disease. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1281. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The ellipsoid zone (EZ) on optical coherence tomography (OCT) has been shown to correlate with retinal function and can be affected in Stargardt disease. Here, we demonstrate a novel technique for tracking the rate of EZ loss as an indicator of disease progression.
31 eyes of 16 Stargardt patients with genetically confirmed ABCA4 gene mutations and follow-up visits separated by at least 12 months were identified for retrospective review. Spectral domain optical coherence tomography (SD-OCT) macula volume scans centered at the fovea covering an area of 20 degree x 20 degree with 49 B-scans were obtained with Spectralis HRA+OCT (Heidelberg Engineering, Heidelberg, Germany). The region of EZ loss was marked on each B-scan and the total area of EZ loss was calculated for the entire volume scan. The yearly rate of EZ loss was then calculated for each eye. A random subset of 12 eyes was re-analyzed by the primary grader to assess intra-grader reliability, and the same subset was analyzed by a second grader to assess inter-grader reliability. Reliability was calculated as the intraclass correlation (ICC) based on a two-way mixed effect model.
The patients were followed for a mean of 2 years (range 1-4.7 years). The rate of area of EZ loss was 0.32mm2/year. The absolute difference of the area of EZ loss on test-retest for the first grader was 0.09mm2, and between graders was 0.16mm2. The ICC of both intra-grader as well as inter-grader reliability was excellent at 0.99.
Tracking the area of EZ loss as seen on macular volume scans on SD-OCT in Stargardt is a sensitive and reliable method for monitoring disease progression. The rate of disease progression found in this study is comparable to reports in the literature.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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