Abstract
Purpose :
The purpose of this study was to quantify retinal capillary density and foveal avascular zone (FAZ) area of normal subjects according to their ethnicity, using optical coherence tomography angiography (OCTA).
Methods :
All eyes in this cross-sectional study underwent Swept source OCTA (Triton, Topcon, Tokyo, Japan). Parafoveal (3 × 3 mm) OCTA scans were obtained on healthy Caucasian and black Africans volunteers. OCTA scans were assessed and processed. The FAZ area and capillary density at the level of both the superficial (SCP) and deep capillary plexus (DCP) were automatically measured using a custom-made software combining vessel binarization and skeletonization.
Results :
We included 22 eyes of 11 healthy Caucasian volunteers, and 30 eyes of 15 black African volunteers in the analysis. Mean subject age was 35.3 and 44.2 years (p=0.09) and there were 9 (91%) and 7 (47%) women respectively in the Caucasian, and African groups. The mean FAZ dimension was significantly smaller, and the overall vessel density higher in the SCP and in the DCP of Caucasian patients in comparison to Black African patients. Mean FAZ area was 0.255 +/- 0.056 mm2 at the SCP and 0.26 +/- 0.06 mm2 at the DCP in the Caucasian group versus 0.35 +/- 0.08 mm2 at the SCP (p=0.001) and 0.35 +/- 0.1 mm2 at the DCP (p=0.01) in the African group. The mean vessel density at the SCP was of 40.5% +/- 0.8 in Caucasians versus 30.3% +/- 1 in Africans (p<0.0001). The mean vessel density at the DCP was of 46.9% +/- 0.5 in Caucasians versus 37.6% +/- 0.9 in Africans (p<0.0001).
Conclusions :
SCP and DCP vessel density is lower in the parafoveal location of black Africans compared to Caucasians probably due to a larger FAZ area. Ethnicity-matched measurements of the control population need to be used for comparison in OCTA studies regarding vascular diseases.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.