Genetic risk of primary open-angle glaucoma. Population-based familial aggregation study.

OBJECTIVES

To study familial aggregation of primary open-angle glaucoma in a general population and to determine the absolute and relative risks for first-degree relatives.

METHODS

First-degree relatives of patients with glaucoma (n = 48) and control subjects (n = 155) from the population-based Rotterdam Study underwent a standardized examination, including perimetry.

MAIN OUTCOME MEASURES: Intraocular pressure, vertical cup-disc ratio; and the presence of glaucoma, defined as a visual field defect with a cup-disc ratio of 0.7 or higher or asymmetry of 0.3 or higher between both eyes.

RESULTS

The prevalence of glaucoma was 10.4% in siblings of patients, 1.1% in offspring of patients, 0.7% in siblings of controls, and 0% in offspring of controls. Life-time risk of elevated intraocular pressure in relatives of patients vs relatives of controls was 42.5% vs 6.7%, of enlarged cup-disc ratio was 62.2% vs 16.6%, and of glaucoma was 22.0% vs 2.3%, yielding a risk ratio for glaucoma of 9.2 (95% confidence interval = 1.2-73.9). The population-attributable risk of glaucoma was 16.4%.

CONCLUSIONS

In a general population, relatives of patients with glaucoma have a strongly increased risk of glaucoma. Enlarged cup-disc ratio, not intraocular pressure, was the earliest and most prominent feature of familial aggregation. Further studies are needed to disentangle the genetic components of the increased familial risk.