Family studies in glaucoma.

Two groups of patients with a family history of chronic open-angle glaucoma were compared with a normal population of 5919 individuals studied during the Bedford Glaucoma Survey. The mean screening intraocular pressure was significantly raised in both groups with a family history of chronic open-angle glaucoma. The prevalence rate of a raised intraocular pressure was 3.81 times that found in the normal population. This relationship was maintained when age-dependent prevalence rates were evaluated. No correlation between raised intraocular pressure and type of familial involvement could be determined. A 10- to 12-year follow-up of one group with a family history for open-angle glaucoma (101 patients) showed that 3% developed confirmed glaucoma, while an additional 5.9% were diagnosed as suspected chronic open-angle glaucoma. A letter survey of this group showed that 9 out of 63 respondents knew of additional family members who developed glaucoma over this 10-12-year period.