Name

Différences ethniques dans les mesures normales de la densité capillaire rétinienne et la zone avasculaire fovéale

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 (3X3mm)OCTAscans were obtained on  healthy Caucasian and black Africans volunteers.OCTA scans were assessed and processed.the FAZ area and capillary density a the level of both the superficial(SCP) and deep capillary plexus (DCP) were automatically measured using a custom-made software combining vessel binarizationand skeletonization.

RESULTS:we included 22 eyes of 11healthy Caucasian volunteers,and 30 eyes of 15 Black Africans volunteers in the analysis.Mean subject age was 35.3and 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 significatly 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 Caucasian versus 30.3% +/_ 1 in African( p<0.0001).The mean vessel density at the DCP was of 46.9%+/_0.5 in Caucasian versus 37.6%+/_0.9 in African(p<0.0001).

the small size of the Caucasian faz is probably responsible for the highest density of the retinal capillaries of the superficial plexus(SCP) and deep plexus (DCP) in this zone, compared to the black African subjects, in whom the largest size of the faz is responsible for a weaker density of the retinal capillary of the superficial plexus and deep plexus

CONCLUSION :SCP and DCP vessel density seems lower in the parafoveal location of Black African compared to Caucasians while FAZ area is larger.Ethnicity-matched measurements of the control population need to be used for comparison in OCTA studies regarding vascular diseases.