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Hao Zhou, Yining Dai, Giovanni Gregori, Philip Rosenfeld, Jacque Duncan, Daniel Schwartz, Ruikang Wang; Measure morphometry of retinal pigment epithelium complex and choriocapillaris automatically using SS-OCT. Invest. Ophthalmol. Vis. Sci. 2020;61(9):PB00127.
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The retinal pigment epithelium (RPE)-Bruch’s membrane (BM)-choriocapillaris (CC) complex has inter-dependent symbiotic relationship and undergoes alterations with aging and in disease. Despite the importance of the RPE-BM-CC complex, few quantitative studies have reported their in vivo morphology and how they change in aging. We report the development of an automated method to measure morphological features of the RPE, BM and CC using a commercially available swept source OCT (SS-OCT) system.
The 6×6 mm macular scans were acquired using SS-OCT (PlexElite, Carl Zeiss Meditec Inc.) from one eye of each subject. The locations of the inner segment/outer segment (IS/OS), RPE and CC were determined by OCT and OCTA A-scan intensity profiles, which were used to calculate the mean IS/OS-to-RPE distance, mean RPE-to-CC distance, mean RPE-to-CC outer boundary distance, mean RPE thickness and mean CC thickness across the entire scan volume (Figure 1).
Two groups of 40 normal subjects: younger age group (n=20, 30.3 ± 5.72 years, axial length = 24.2 ± 0.96 mm) and older age group (n=20, 80.8 ± 4.12 years, axial length = 23.5 ± 0.93 mm) were recruited. CC locations were confirmed qualitatively with pixel-by-pixel moving of the en face OCT/OCTA images. Repeatability of the measurements showed a coefficient of variance < 5% for all the cases. Relative distance and thickness maps of the RPE-BM-CC complex were generated for visualization of regional changes. We observed thinner CC, thinner RPE and increased RPE-to-CC distance in the older age group. Correlation between CC thickness and choroid thickness suggests that the CC thins with the overall thinning of the choroid (Figure 2).
The proposed morphometric metrics should be useful to reveal more details of RPE-BM-CC complex, provide better understanding of the CC in three dimensions, and further investigate potential functional relationships between RPE, BM and CC, and their involvement in age-related ocular diseases.
This is a 2020 Imaging in the Eye Conference abstract.
Fig 1. Mean IS/OS-to-RPE distance, mean RPE-to-CC distance, mean RPE-to-CC outer boundary distance, mean RPE thickness and mean CC thickness across the entire scan volume were calculated from OCT and OCTA A-scan intensity profiles.
Fig.2. Metrics of the RPE-BM-CC complex and CC change with aging and mean choroid thickness (MCT).
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