The Role of Ocular Blood Flow in the Pathogenesis of Glaucomatous Damage

Abstract

Ocular blood flow (OBF) is on average lower in glaucoma patients than in healthy controls. This reduction is more pronounced in normal-tension than in high-tension glaucoma and more distinct in cases with progressing damage as compared to those with stable disease. Besides a secondary component caused by atrophy, there is an important primary component of OBF reduction, which also has a predictive value. The fact that hypoxia-related factors are upregulated in eyes of glaucoma patients indicates oxygen depletion. It is, however, not constant hypoxia, but rather the fluctuation of oxygen supply that leads to tissue damage, likely because of oxidative stress. Low perfusion pressure and disturbed autoregulation are the major causes of insufficient and fluctuating oxygen supply, and both systemic hypotension and disturbed autoregulation are often consequences of the primary vascular dysregulation syndrome. The observed splinter hemorrhages in these patients are a consequence of a local breakdown of the blood–brain or blood–retinal barrier. The often associated vein occlusions can be a consequence of a local vein dysregulation.