Rate of progression in open-angle glaucoma estimated from cross-sectional prevalence of visual field damage

Abstract

Purpose: To estimate the rate of visual field loss in persons with open-angle glaucoma.

Methods: The visual field data obtained by Goldmann perimetry from 151 persons with open-angle glaucoma from the Baltimore Eye Survey were graded on a nine-level severity scale. Approximately one half of these persons had previously diagnosed glaucoma and were being treated. Using regression analysis, their scores were compared to other features, including age, vertical cup/disk ratio, treatment status, gender, race, and intraocular pressure. These data were used to estimate the average rate of progressive field loss and blindness in glaucoma.

Results: Among 112 black subjects, the severity of visual field damage was significantly associated with age (P < .02), history of glaucoma treatment (P < .04), and intraocular pressure (P < .0001). Using the relationship between age and damage, we estimated that the rate of deterioration of black glaucoma subjects was two grading levels per decade, which is consistent with previous reports. For 39 white subjects, the inclusion of age improved the model relationship between damage score and other variables. The best estimate of individual damage rate for whites was similar to that in blacks. However, the statistical association of age and damage in whites was less strong than in blacks, possibly because of fewer white subjects in the sample.

Conclusions: While glaucoma is a frequent cause of visual disability, rate of progressive visual field loss is not sufficient to lead to bilateral blindness in the majority of those affected. Aggressiveness of glaucoma therapy should be related to the rate of visual field loss stressing confirmation of field progression.