Racial differences in the correlations between structural parameters and ocular blood flow in healthy eyes

Koosha Ramezani,Alon Harris,Jennifer Eikenberry,Carine Olinde,Lyne Racette,Darrell Wudunn,Betul Kaskan,Fang-I Chu,Leslie A Tobe,Brent Siesky

doi:10.35119/maio.v2i1.57

Abstract

Purpose: This study aimed to assess differences in the relationship between structural parameters and ocular blood flow between persons of African (AD) and European descent (ED) with healthy eyes.Methods: The relationship between structural and ocular blood flow parameters was assessed in 46 participants (20 AD, 26 ED) with healthy eyes. Disc area (DA), rim area (RA), and retinal nerve fiber layer (RNFL) thickness were measured. Retrobulbar blood flow was assessed in the ophthalmic (OA), central retinal (CRA), nasal (NPCA) and temporal short posterior ciliary arteries (TPCA). Peak systolic velocity (PSV), end diastolic velocity (EDV) and resistive index (RI) were assessed. Retinal capillary blood flow was also evaluated. Differences between the correlations were determined using the Fisher r-to-z transformation.Results: Significant differences in correlations were observed between the AD and ED groups in the CRA, where PSV and DA were positively correlated in AD (r=0.43) and negatively correlated in ED (r=-0.36) (Δr=0.79; P=0.01). A similar finding was observed for PSV and RA (AD: r=0.39; ED: r=-0.23; Δr=0.62; P=0.04). In the inferior hemifield for ED group only, percentage of avascular space and RNFL thickness were positively correlated (r=0.51, P=0.01) and mean retinal flow and RNFL thickness were negatively correlated (r=-0.50, P=0.01).Conclusion: The relationship between structural parameters and the blood supply to the superficial layer of the retina was significantly different in the healthy eyes of AD compared to ED. More research is required to show how these differences may affect glaucomatous risk.

Highlights

Primary open-angle glaucoma (POAG) is the leading cause of irreversible blindness in the African American population of the United States.[1]
No significant differences were observed in demographics and general health data between participants of AD and European descent (ED) including age, sex, family history of glaucoma, cardiovascular diseases, intraocular pressure (IOP), mean arterial pressure (MAP), CCT, and ocular perfusion pressure (OPP) (Table 1)
No significant differences between groups were observed for all other retrobulbar blood flow, retinal capillary blood flow, or structural parameters

Summary

Introduction

Primary open-angle glaucoma (POAG) is the leading cause of irreversible blindness in the African American population of the United States.[1]. Large population-based trials have linked reduced ocular perfusion pressure (OPP) to the prevalence, incidence, and progression of glaucoma.[4,5] Retinal,[6] choroidal,[7] and retrobulbar[8] blood flow deficiencies have been reported in patients with POAG. Other vascular conditions such as systemic hypertension,[9] aging of the vasculature,[10] and optic disc hemorrhage[11] have been associated with POAG. This suggests that patients of AD may have a stronger vascular component in the pathogenesis of glaucoma than patients of ED.[13,14]

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Conclusion