Original Paper

The Response of Retrobulbar Vasculature to Hypercapnia in Primary Open-Angle Glaucoma and Ocular Hypertension
D. Sines^a, A. Harris^a, B. Siesky^a, I. Januleviciene^d, C.L. Haine^{b, c}, C.W. Yung^a, Y. Catoira^a, H.J. Garzozi<sup>e

a</sup>Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Ind., and
^bSouthern College of Optometry and
^cDepartment of Veterinary Administration Medical Center, Memphis, Tenn., USA;
^dEye Clinic, Kaunas University of Medicine, Kaunas, Lithuania;
^eDepartment of Ophthalmology, Bnai Zion Medical Center, Rappaport School of Medicine, Technion, Haifa, Israel

Address of Corresponding Author

Ophthalmic Res 2007;39:76-80 (DOI: 10.1159/000099241)

  Key Words

• Hypercapnia
• Retrobulbar vasculature, vasodilatation
• Vasospasm

  Abstract

Purpose: To evaluate the physiological effects of hypercapnia on the retrobulbar vasculature in ocular hypertension (OH) and open-angle glaucoma (OAG). Methods: Peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistive index (RI) of the ophthalmic (OA) and central retinal arteries (CRA) were evaluated in 12 eyes with OH and 8 eyes with OAG using color Doppler imaging. Measurements were taken before and during hypercapnia. Results: Patients with OAG were found to have increased EDV (p < 0.035) of the CRA, and decreased PSV (p < 0.097) and EDV (p < 0.098) of the OA, during hypercapnia. Patients with OH had increased PSV (p < 0.062) and EDV (p < 0.072) of the CRA during hypercapnia. Patients with OH also demonstrated a greater percent change in the calculated RI (p < 0.065) of the CRA in response to hypercapnia when compared to OAG. The mean RI of the CRA decreased during hypercapnia. Discussion: Patients with OH were found to have a normal vasodilatory response within the retrobulbar vasculature during hypercapnia resulting in increased volumetric blood flow to the retina while patients with OAG did not, suggesting there is vasospasm at or downstream from the CRA resulting in decreased volumetric blood flow to the retina.

Copyright © 2007 S. Karger AG, Basel

  Author Contacts

Alon Harris, PhD
Letzter Chair of Ophthalmology, Indiana University School of Medicine
702, Rotary Circle, Room 137
Indianapolis, IN 46202 (USA)
Tel. +1 317 278 0177, Fax +1 317 279 1007, E-Mail alharris@indiana.edu

  Article Information

Accepted after revision: October 10, 2006
Received: March 3, 2006
Published online: February 2, 2007
Number of Print Pages : 5
Number of Figures : 1, Number of Tables : 1, Number of References : 13