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

Supplementary Files


How to Cite

Ramezani K, Harris A, Siesky B, Olinde C, WuDunn D, Eikenberry J, Chu F-I, Tobe LA, Kaskan B, Racette L. Racial differences in the correlations between structural parameters and ocular blood flow in healthy eyes. MAIO [Internet]. 2018 Feb. 16 [cited 2024 Jun. 16];2(1):29-41. Available from: https://www.maio-journal.com/index.php/MAIO/article/view/57

Copyright notice

Authors who publish with this journal agree to the following terms:

  1. Authors retain copyright and grant the journal right of first publication, with the work twelve (12) months after publication simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work’s authorship and initial publication in this journal.

  2. After 12 months from the date of publication, authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.


glaucoma; ocular blood flow; posterior segment; racial difference


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.



Congdon N, O’Colmain B, Klaver CC, et al. Causes and prevalence of visual impairment among adults in the United States. Arch Ophthalmol. 2004;122(4):477-485.

Friedman DS, Wolfs RC, O’Colmain BJ, et al. Prevalence of open-angle glaucoma among adults in the United States. Arch Ophthalmol. 2004;122(4):532-538.

Racette L, Wilson MR, Zangwill LM, Weinreb RN, Sample PA. Primary open-angle glaucoma in blacks: a review. Surv Ophthalmol. 2003;48(3):295-313.

Leske MC, Wu S-Y, Nemesure B, Hennis A. Incident open-angle glaucoma and blood pressure. Arch Ophthalmol. 2002;120(7):954-959.

Tielsch JM, Katz J, Sommer A, Quigley HA, Javitt JC. Hypertension, perfusion pressure, and primary open-angle glaucoma: a population-based assessment. Arch Ophthalmol. 1995;113(2):216-221.

Chung HS, Harris A, Kagemann L, Martin B. Peripapillary retinal blood flow in normal tension glaucoma. Br J Ophthalmol. 1999;83(4):466-469.

Yin ZQ, Vaegan, Millar TJ, Beaumont P, Sarks S. Widespread choroidal insufficiency in primary open-angle glaucoma. J Glaucoma. 1997;6(1):23-32.

Harris A, Sergott RC, Spaeth GL, Katz JL, Shoemaker JA, Martin BJ. Color Doppler analysis of ocular vessel blood velocity in normal-tension glaucoma. Am J Ophthalmol. 1994;118(5):642-649.

Galassi F, Sodi A, Ucci F, Renieri G, Pieri B, Baccini M. Ocular hemodynamics and glaucoma prognosis: a color Doppler imaging study. Arch Ophthalmol. 2003;121(12):1711-1715.

Ehrlich R, Kheradiya NS, Winston DM, Moore DB, Wirostko B, Harris A. Age-related ocular vascular changes. Graefes Arch Clin Exp Ophthalmol. 2009;247(5):583-591.

Drance S, Anderson DR, Schulzer M. Collaborative Normal-Tension Glaucoma Study G. Risk factors for progression of visual field abnormalities in normal-tension glaucoma. Am J Ophthalmol. 2001;131(6):699-708.

Siesky B, Harris A, Racette L, et al. Differences in ocular blood flow in glaucoma between patients of African and European descent. J Glaucoma. 2015;24(2):117.

Kanakamedala P, Harris A, Siesky B, et al. Optic nerve head morphology in glaucoma patients of African descent is strongly correlated to retinal blood flow. Br J Ophthalmol. 2014;98(11):1551-1554.

Siesky B, Harris A, Racette L, et al. Differences in ocular blood flow in glaucoma between patients of African and European descent. J Glaucoma. 2015;24(2):117-121.

Racette L, Liebmann JM, Girkin CA, et al. African Descent and Glaucoma Evaluation Study (ADAGES): III. Ancestry differences in visual function in healthy eyes. Arch Ophthalmol. 2010;128(5):551-559.

Kaskan B, Ramezani K, Harris A, et al. Differences in ocular blood flow between people of African and European descent with healthy eyes. J Glaucoma. 2016;25(9):709-715.

Rusia D, Harris A, Pernic A, et al. Feasibility of creating a normativedatabase of colour Doppler imaging parameters in glaucomatous eyes and controls. Br J Ophthalmol. 2011;95(9):1193-1198.

Jonescu-Cuypers C, Harris A, Wilson R, et al. Reproducibility of the Heidelberg retinal flowmeter in determining low perfusion areas in peripapillary retina. Br J Ophthalmol. 2004;88(10):1266-1269.

Williamson TH, Harris A. Color Doppler ultrasound imaging of the eye and orbit. Surv Ophthalmol. 1996;40(4):255-267.

Fingeret M, Flanagan J, Liebmann JM. The essential HRT primer. San Ramon: Jocoto Advertising; 2005.

Kenny DA. Statistics for social and behavioral science. Library of Congress; 1987.

R Core Team. R: A language and environment for statistical computing. Vienna, Austria: R Foundation for Statistical Computing; 2017. Available from: http://www.R-project.org/.

Resch H, Schmidl D, Hommer A, et al. Correlation of optic disc morphology and ocular perfusion parameters in patients with primary open angle glaucoma. Acta Ophthalmol. 2011;89(7):e544-549.

Siesky B, Harris A, Carr J, et al. Reductions in retrobulbar and retinal capillary blood flow strongly correlate with changes in optic nerve head and retinal morphology over 4 years in open-angle glaucoma patients of African descent compared with patients of European descent. J Glaucoma. 2016;25(9):750-757.

Stalmans I, Vandewalle E, Anderson DR, et al. Use of colour Doppler imaging in ocular blood flow research. Acta Ophthalmol. 2011;89(8):e609-e630.

Balazsi AG, Drance SM, Schulzer M, Douglas GR. Neuroretinal rim area in suspected glaucoma and early chronic open-angle glaucoma: correlation with parameters of visual function. Arch Ophthalmol. 1984;102(7):1011-1014.

Rosenberg NA, Pritchard JK, Weber JL, et al. Genetic structure of human populations. Science. 2002;298(5602):2381-2385.

Guidoboni G, Harris A, Arciero JC, et al. Mathematical modeling approaches in the study of glaucoma disparities among people of African and European descents. J Coupled Syst Multiscale Dyn. 2013;1(1):1-21.