Objectives: To determine the prevalence and the main types of glaucoma in a representative adult population in rural Zululand, and to describe the distribution of glaucoma-related variables in healthy subjects and those with glaucoma.

Design: A population-based, cross-sectional study.

Setting: Hlabisa district, Northern KwaZulu-Natal Province, South Africa.

Participants: Resident individuals of Zulu ethnic origin, 40 years or older.

Main outcome measures: Glaucoma was diagnosed by means of strict objective criteria, based on binocular indirect ophthalmoscopic optic disc appearances validated by results of disc photography and threshold visual field testing.

Results: From an eligible sample of 1115 subjects, 1005 (90.1%) were examined in the survey. The adjusted prevalence of glaucoma of all types was 4.5%, and primary open-angle glaucoma accounted for 2.7%. Secondary glaucoma occurred with an adjusted prevalence of 1.7%, of which the principal contributors were exfoliative and aphakic glaucoma. The prevalence of primary angle-closure glaucoma was low. Normal tension (intraocular pressure, < or =21 mm Hg) was measured in 16 (57.1%) of 28 cases of primary open-angle glaucoma. Age- and sex-adjusted prevalence of bilateral blindness was 3.2%, which was exclusively due to glaucoma in 9 (22.0%) of 41 cases.

Conclusions: Primary and secondary glaucoma constitute a significant public health problem in rural Zululand. The prevalence and types of glaucoma vary among different black populations.