Correlation Among Choroidal, Parapapillary, and Retrobulbar Vascular Parameters in Glaucoma SUNIL DEOKULE, GIANMARCO VIZZERI, ANDREAS G. BOEHM, CHRISTOPHER BOWD, FELIPE A. MEDEIROS, AND ROBERT N. WEINREB ● PURPOSE: To study and compare the correlation among choroidal, parapapillary, and retrobulbar vascular param- eters in healthy subjects, glaucoma suspects, and open- angle glaucoma (OAG) patients. ● DESIGN: Prospective observational clinical study. ● METHODS: The study included one randomly selected eye from 21 normal subjects, 30 glaucoma suspects based on optic disc appearance, and 22 OAG patients. The pulsatile ocular blood flow (POBF), a measure of choroi- dal blood flow, was assessed using ocular blood flow analyzer whereas parapapillary blood flow and blood velocity of retrobulbar blood vessels were measured using scanning laser Doppler flowmetry and color Doppler imaging, respectively. All vascular parameters along with blood pressure and intraocular pressure measurements were obtained within a 2-hour period. Univariate regres- sion analyses were used to evaluate the correlation of POBF values with parapapillary blood flow values, ret- robulbar blood flow velocities, and resistive index, which represents vascular resistance, in each group. Two mul- tiple linear regression models were created based on results of univariate analyses and included POBF, mean parapapillary blood flow, age, and mean ocular perfusion pressure; and POBF, temporal short posterior ciliary artery resistive index, age, and mean ocular perfusion pressure. ● RESULTS: POBF was significantly associated with para- papillary blood flow (r 2  0.54; P < .001, positive correlation) and temporal short posterior ciliary artery resistive index (r 2  0.39; P < .001, negative correla- tion) in normal subjects. Results were consistent when corrected for age, intraocular pressure, and blood pres- sure parameters. POBF values did not correlate with parapapillary blood flow values or temporal short poste- rior ciliary artery resistive index in glaucoma suspects or OAG patients. ● CONCLUSION: The relationships of POBF with para- papillary blood flow and calculated retrobulbar vascular resistance differs among normal subjects, glaucoma sus- pects, and OAG patients. This provides further evidence of vascular dysregulation in OAG. (Am J Ophthalmol 2009;147:736 –743. © 2009 by Elsevier Inc. All rights reserved.) V ASCULAR FACTORS HAVE AN IMPORTANT ROLE IN the development and progression of open-angle glaucoma (OAG). 1,2 OAG patients are shown to have vascular dysregulation that leads to either local vasospasm or impaired autoregulation. 3–7 Normal autoreg- ulation is essential to maintain a stable blood flow in an eye in relation to local metabolic activity, despite changes in ocular perfusion pressure. 8,9 Assessment of pulsatile ocular blood flow [POBF] (measure of pulsatile choroidal blood flow), 10,11 color Doppler imaging (CDI) of retrobul- bar blood vessels (CDI, a measure of retrobulbar red blood cell velocity and resistive index that represents down- stream resistance to blood flow), 12 and scanning laser Doppler flowmeter [SLDF] (a measure of superficial retinal and anterior optic nerve head [ONH] capillary blood flow) 13,14 each provide a unique view of ocular hemody- namics. Some cross-sectional studies using these technol- ogies have reported reduced retrobulbar blood flow, choroidal blood flow, and retinal blood flow in OAG. 15–19 Further, the regulation of blood flow, particularly when challenged, seems to be different in OAG patients com- pared to normal subjects. 20,21 Although different ocular vascular beds respond to various stimuli independent of each other, their responses correlate with each other in normal subjects. 22 However, to the best of our knowledge there have been no studies evaluating the relationship of parameters among 3 differ- ent ocular vascular beds in OAG. Given the evidence of vascular dysregulation in OAG, we hypothesized that the relationship between choroidal, retinal, and retrobulbar vascular parameters may differ among normal subjects, glaucoma suspects, and OAG. METHODS THIS WAS AN OBSERVATIONAL CLINICAL STUDY. PARTICI- pants included subjects from the ongoing Diagnostic In- novations in Glaucoma Study (DIGS). All available subjects who consented to the study and had ocular blood flow measurements using all three techniques (ie, POBF, CDI, and SLDF) were included in the study. One eye was Supplemental Material available at AJO.com. Accepted for publication Oct 23, 2008. From the Hamilton Glaucoma Center, Department of Ophthalmology, University of California, San Diego, La Jolla, California. Inquiries to Robert N. Weinreb, Hamilton Glaucoma Center, Depart- ment of Ophthalmology, University of California, 9415 Campus Point Dr, La Jolla, CA 92037; e-mail: weinreb@eyecenter.ucsd.edu © 2009 BY ELSEVIER INC.ALL RIGHTS RESERVED. 736 0002-9394/09/$36.00 doi:10.1016/j.ajo.2008.10.020