Abstract
Purpose :
Black populations in the United States have been shown to have a higher risk of vision loss by diabetic retinopathy (DR) compared to white populations, even while controlling for known risk factors. However, limited studies exist that investigate the factors underlying the higher vulnerability of black populations to the complications of DR. The purpose of this cross-sectional study was to investigate differences in the retinal vessel blood flow between black and white populations by employing optical coherence tomography angiography (OCTA).
Methods :
OCTA (Optovue RTVue XR Avanti with AngioVue) was used to image 81 eyes of 17 healthy black (mean age 27.7±4.3y) and 24 healthy white (mean age 31.1±8.2y) subjects who were matched for age, refractive error, and image quality. Percent of macular vessel density (VD), area of blood flow (ABF) in the 3x3mm macular scan, and area of foveal avascular zone (FAZ) in the superficial and deep capillary plexuses (SCP and DCP, respectively) were automatically measured with OCTA. Linear mixed models were used to estimate the difference between racial groups, and marginal means (±standard error) were calculated. The study protocol was approved by the Institutional Review Board.
Results :
In the SCP, black subjects had decreased VD at the fovea (28.58±0.87% vs 32.66±0.74%; p=0.012), with no difference outside the fovea. In the DCP, black subjects displayed significantly decreased VD outside the fovea (59.63±0.36% vs 60.96±0.31%; p=0.008), and a trend towards decreased VD at the fovea (29.38±1.13% vs 33.56 ±0.96%; p=0.052). Black subjects had smaller ABF in the DCP (4.651±0.077mm2 vs 4.882±0.065mm2; p=0.031) and choriocapillaris (5.473±0.024mm2 vs 5.642±0.020mm2; p<0.001). Black subjects had larger FAZ in both the SCP (0.304±0.017mm2 vs 0.214±0.015mm2; p=0.006) and DCP (0.347±0.017mm2 vs 0.258±0.015mm2; p=0.005).
Conclusions :
To our knowledge, this is the first report showing that black subjects have decreased blood flow in both macular retina vessels and choriocapillaris, even at a young age and in the absence of any systemic conditions. These findings suggest there are previously unknown pathways involved in the increased sensitivity of black populations in the United States to the events of blood vessel loss seen in DR, and signify the importance of individually tailoring treatments for patients with DR.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.