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Hao Zhou, Prashanth Iyer, Qinqin Zhang, kelly chen, yingying shi, Giovanni Gregori, Philip J Rosenfeld, Ruikang K Wang; Morphometric measurements of Bruch’s membrane and choriocapillaris in eyes with Sorsby Macular Dystrophy using SS-OCTA. Invest. Ophthalmol. Vis. Sci. 2021;62(8):2446.
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© ARVO (1962-2015); The Authors (2016-present)
The extrapolated retinal pigment epithelium (eRPE)/Bruch’s membrane (BM) complex undergoes alterations with aging and in disease. Despite the importance of the eRPE/BM complex, few quantitative studies have reported its in vivo morphology and how it changes with disease. We have developed an automated method to measure morphological features of the eRPE/BM complex using a commercially available swept source OCTA (SS-OCTA) system and studied the correlations between the BM and choriocapillaris (CC) flow deficits (FD) in eyes with Sorsby Macular Dystrophy (SMD).
6×6 mm macular scans were acquired using SS-OCTA imaging (PLEX® Elite, Carl Zeiss Meditec Inc.) from a patient with SMD and age-matched normal subjects. Structural OCT cubes were converted into linear scales to obtain higher contrast at the RPE layer. The locations of the RPE and CC in each subfield were determined by OCT/OCTA A-scan intensity profiles, which were used for enface mapping of the eRPE-to-CC distances, that is equivalent to the BM thickness (Fig 1). RPE structure images were obtained by sum projection of selected OCT slab. CC enface images were generated from a 20-µm OCTA slab beneath BM and CC FDs were calculated using a previously validated thresholding method.
A patient with Sorsby Macular Dystrophy and age-matched normal subjects were recruited. The locations of reticular pseudodrusen (RPD) were observed on a 20-µm thick enface structure slab positioned 20-µm above the RPE. The regional changes in the BM thickness were visualized on the enface eRPE-to-CC distance maps. We correlated an increase in the eRPE-to-CC distance and a decrease of CC flow in the regions with RPD in eyes with SMD (Fig 2).
Co-localization of RPD, thickened BM, and CC flow impairment were observed in eyes with Sorsby Macular Dystrophy. The proposed morphology metric should be useful to reveal more details of eRPE/BM complex, providing an opportunity to investigate potential functional relationships between the RPE, BM and CC, and their involvement in ocular diseases.
This is a 2021 ARVO Annual Meeting abstract.
Fig 1. Enface mapping of eRPE-to-CC distance was calculated by identifying ePRE/BM peak and CC peak from OCT and OCTA A-scan intensity profiles, respectively.
Fig.2. RPE enface structure, eRPE/BM complex (eRPE-to-CC distance), CC flow and CC FD (green) in a normal eye (A-D) and an eye with Sorsby Macular Dystrophy (E-H), respectively.
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