Color Doppler Study of the Ophthalmic Artery and the Central Retinal Artery in Patients with Primary Open-Angle Glaucoma

Abstract

Primary open angle glaucoma (POAG) is a syndrome of a progressive optic neuropathy characterized by optic nerve head excavation and visual field defects with or without elevated intraocular pressure. Theories concerning the pathogenesis can be grouped into two broad categories: the mechanical theory and the vascular theory. (IOJ)

Color Doppler imaging is a recent non-invasive method that allows examination of the retrob ulbar circulation. It allows information about the blood flow to be superimposed in color on a grayscale ultrasound image,

enabling direct visualization of the specific vessels to be examined. <97 It

measures velocities of blood flow in the vessels under study in various phases of the cardiac cycle. Because the measured values are influenced by the angle between the ultrasound probe and the direction ofthe blood flow, it is more accurate to depend on the ratios of the blood flow velocities to one another measured at one time. These ratios are the resistivity index and the pulsatility index. Both indicate resistance to the blood flow in a certain vessel d istal to the point of measurement. (l 2)

This study was conducted with the aim of studying the blood flow indices obtained by color Doppler imaging of the ophthalmic artery (OA) and the central retinal artery (CRA) and to correlate them with other glaucoma parameters [I ntraocular pressure (lOP), Cup-disc ratio (C/D), and visual field parameters (Mean deviation (MD) and Pattern standard deviation (PSD))]