Epidemiology of angle-closure glaucoma - Prevalence, clinical types, and association with peripheral anterior chamber depth in the Egna-Neumarkt glaucoma study

Objectives To assess the prevalence of primary angle-closure glaucoma (PACG ), the frequency of its different clinical presentations, and its associati on with peripheral anterior chamber depth in a defined population in Northe rn Italy. Design: Cross-sectional epidemiologic study in a defined population. Participants: All subjects resident in the Egna-Neumarkt area of the South Tyrol Region (Northern Italy) and more than 40 years of age were invited to undergo an ophthalmologic examination. Interventions After the screening examination, subjects with suspected glau coma were re-examined at the screening center to confirm the diagnosis. All cases that still proved suspect after the second examination underwent a t hird phase of investigations and were classified as healthy or as definitel y glaucomatous. Each subject was examined according to a standard protocol, including medical history interview, retraction and visual acuity determin ation, ocular biomicroscopy, evaluation of peripheral anterior chamber dept h by means of the Van Herick method, applanation tonometry, optic disc eval uation, and computerized perimetry. Gonioscopy was not performed during ini tial screening but only in all selected patients in the second and third ph ases of investigations. The diagnosis of PACG was made on the basis of the concomitant presence of at least two of the following criteria: intraocular pressure greater than or equal to 22 mmHg, glaucomatous optic disc abnorma lities, glaucomatous visual field defects. In addition, biomicroscopic or g onioscopic evidence of angle closure was also necessary. Main Outcome Measures.' Percentage distribution of peripheral anterior cham ber depths, prevalence of angle-closure glaucoma, and frequency of the diff erent PACG clinical presentations. Results: Four thousand two hundred ninety-seven subjects were examined (73. 9% overall participation rate). The peripheral depth of the anterior chambe r according to the Van Herick method was grade 2 in 14.7%, grade 1 in 2.5%, and grade 0 in 0.3% of the population. The overall prevalence of angle-clo sure glaucoma was 0.6% (26 cases). Five of these were cases of previous acu te attacks resolved by therapy, three were cases of chronic angle-closure a fter acute attacks, three were intermittent angle-closure glaucomas, and 15 were chronic angle-closure cases. Conclusions: Occludable angles were more frequent than in other white popul ations previously studied. The prevalence of PACG is not as low as is usual ly believed; this type of glaucoma accounts for more than a quarter of all glaucomas found in the Egna-Neumarkt population. The most frequent clinical presentation is chronic angle-closure glaucoma. (C) 2000 by the American A cademy of Ophthalmology.