Ocular Vessel Density Among Healthy Subjects of Different Ethnicities

Abstract

Purpose : Optical coherence tomography angiography (OCTA) is an imaging technology that evaluates volumetric retinal vasculature, with a wide variety of applications. In this study we compared the ocular vessel density of healthy subjects among Caucasian, Asian, and Latin ethnicities.

Methods : Healthy subjects with normal comprehensive ophthalmic examination, qualified visual field (VF; Humphrey Field Analyzer; Zeiss, Dublin, CA), OCT (Cirrus HD-OCT Angioplex; Zeiss) optic nerve head (ONH) scans (200x200 ONH cube scan) and OCTA scans (3x3 OCTA ONH cube scans) were included. Subjects with comorbidities affecting the systemic or local micro or macro vasculature and subjects taking medications that modify vessel diameter were excluded. Peripapillary ocular vessel density (VD) was calculated using the device's native software. A univariable model was used to compare VD among ethnicities and a multivariable model was used to describe the associations between VD and cup volume (CV), cup to disc ratio, retinal nerve fiber layer (RNFL), signal strength (SS), and spherical equivalent (SE) refractive error. A mixed effects model was used to account for inter-and intra-subject correlations.

Results : 99 eyes of 66 healthy subjects (39 Caucasian, 46 Asian, and 14 Latin) were included in the study. SE was significantly different among ethnicities (p=0.003), but no significant association was detected with VD (Table). A significantly larger VD was observed in Caucasians vs Asians (p=0.008). No difference was observed in Caucasians vs Latins (p=0.09) or Asians vs Latins (p=0.92). For every mm³ increase of CV the VD decreased 6.93mm/mm², being more significant in Latins (p=0.007). One unit increase of SS was associated with a 0.33mm/mm² (p=0.013) of larger VD for all ethnicities. All other variables included in the model showed no association with VD.

Conclusions : VD is not the same among ethnicities. Among the included global parameters, CV is the only one associated with VD. The difference in VD among different ethnicities and its implications on pathophysiology of retinal diseases needs to be further explored. A normative database considering ethnicity differences should be established in order to include VD measurements in clinical evaluation.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

 

Table. Demographic and clinical characteristics of healthy Caucasian, Asian, and Latin subjects