Part II: Hemodynamic and structural changes in early glaucoma

Abstract

The central theme of the papers in this portion of the volume is a description of early morphological alterations in glaucoma and the manner in which these pathological changes may be altered by medical treatment. The detection and evaluation of pathological change in the retina is completely dependent upon the development of new tools for observing the retina and optic disc. Dr. Airaksinen’s paper described new photographic methods for evaluation of both the optic disc, in particular the neuroretinal rim, and the nerve fiber layer. He demonstrated that changes in the nerve fiber layer precede abnormalities in the optic disc and visual field defects. Dr. Grunwald employed a new method, laser Doppler velocimetry, to analyze the effect of timolol on retinal blood flow. He demonstrated that timolol increased retinal blood flow, and that this effect may result from the increase in perfusion pressure and a change in the manner in which the retina regulates its blood supply. In the normal eye, there is not a significant correlation between perfusion pressure changes and retinal blood flow changes. With timolol treatment, however, a significant correlation between these two variables can be observed. Thus, the retinal blood flow seems to follow more passively the changes in systemic blood pressure after timolol treatment. The data that I presented also demonstrated the utility of computer-aided video analysis for detecting early retinal changes in glaucoma patients. Our experiments with the Optic Nerve Head Analyzer again demonstrated the prognostic value of early changes in the neuroretinal rim in glaucoma patients. Photogrammetry and computer analysis of the optic disc were also emphasized in the study presented by Dr. Schwartz. He demonstrated that treatment with timolol can reduce cupping in the optic disc, and that the bottom portion of the cup was the site of the most pronounced differences between the timolol-treated and untreated eyes. His data also demonstrated the importance of repeated testing of suspect eyes. Such testing permitted the identification of pathological trends that were not apparent in a single examination.