Differences in Retinal Hemodynamics Between African American and Caucasian Patients With Glaucoma

Abstract

Purpose: : The purpose of this study was to examine whether retinal blood flow patterns are different between African Americans and Caucasians with primary open–angle glaucoma (OAG).

Methods: : An analysis of three prior OAG studies carried out at the Glaucoma Research & Diagnostic Laboratories at the Indiana University School of Medicine was performed. Confocal scanning laser Doppler flowmetry [Heidelberg Retinal Flowmeter (HRF), Heidelberg Engineering, Heidelberg, Germany] was used to measure perfusion within peripapillary retinal capillary beds. HRF was taken in superior and inferior temporal retinal fields of a randomly selected study eye. The superior temporal retinal field was examined in thirty five African American and Caucasian OAG patients, and the inferior temporal field was examined in thirty nine African American and thirty Caucasian patients. Data were displayed by histogram, and flow was measured as number of zero flow pixels and number of pixels falling into the 10^th, 25^th, 50^th, 75^th and 90^th percentiles of total flow. This technique also includes discrimination of perfused and avascular tissue, producing measurements of the degree of vascularity of the fundus. All parameters were compared using unpaired, student’s t–tests.

Results: : Caucasians had significantly lower blood flow in the 10^th percentile flow level compared to African Americans (p=0.0446). No other significant differences were found in the 25^th, 50^th, 75^th or 90^th percentiles of retinal flow between the two groups.

Conclusions: : In this cohort of patients with OAG, Caucasians presented with reduced retinal perfusion in the 10^th percentile flow level compared to African–Americans. Ethnic differences in ocular blood flow continue to emerge and may help explain differences in OAG prevalence.

Keywords: clinical (human) or epidemiologic studies: prevalence/incidence • blood supply • clinical (human) or epidemiologic studies: risk factor assessment