Abstract
Purpose :
To investigate the vascular perfusion of retina and choriocapillaris (CC) in diabetic patients without retinopathy using swept source optical coherence tomography angiography (SS-OCTA).
Methods :
SS-OCTA (PLEX® Elite 9000 (ZEISS, Dublin, CA)) running at 100 kHz A-line rate was used to collect 6 x 6 mm2 macular scans from subjects. Three retinal layers and CC layer were segmented by the semi-automatic method. Vessel area density (VAD) and vessel skeleton density (VSD) were calculated on three retinal layers in 1.5mm rim (R1.5), 2.5mm rim (R2.5) and the entire rim (R4.0) that exclude the central 1 mm circle (C1). The non-perfusion area (NPA) was also investigated in R1.5 and R2.5 in three retinal plexuses. Foveal avascular zone (FAZ) area was automatically measured in three retinal layers. For CC, the percentage of flow deficits (FD %) and the average size of FDs were measured in C1, R1.5, and R2.5, as well as the entire 5.0mm circle (C5).
Results :
A total of 16 eyes from 16 diabetic patients without clinically visible retinopathy and 16 control eyes from 16 age-matched nondiabetic subjects were included in this study. Mean duration of diabetes was 2.1 ± 1.20 years. There was no significant difference between the two groups in all retinal quantitative parameters (VAD, VSD, and NPA) within all regions (R1.5, R2.5, and R4, P>0.05). There was no significant difference in the FAZ area between the two groups (all P>0.05). No statistical difference in FD % or average FD size within C1 regions was found between the two groups. Mean FD % in CC was significantly increased in diabetic eyes compared to controls within R1.5 (22.75 % vs. 14.33 %; P < 0.001), R2.5 (15.77 % vs. 9.72 %; P = 0.001), and C5 regions (17.55 % vs. 11.07 %; P < 0.001). Similarly, the average size of FDs was significantly increased in diabetic eyes compared to controls within R1.5 (2823.5 µm2 vs. 1931.9 µm2; P < 0.001), R2.5 (2158.2 µm2 vs. 1618.8 µm2; P = 0.005), and C5 regions (2454.7 µm2 vs. 1799.6 µm2; P = 0.002) .
Conclusions :
CC perfusion was found to be decreased in diabetic patients without retinopathy as compared to age-matched nondiabetic controls, which occurred before the microvascular changes in the macular retina. CC perfusion may be an early predictor for the microvascular changes in the eye at an early stage of diabetes instead of the retinal vasculature.
This abstract was presented at the 2019 ARVO Imaging in the Eye Conference, held in Vancouver, Canada, April 26-27, 2019.