Objective: To assess the prevalence of primary angle-closure glaucoma (PACG), the frequency of its different clinical presentations, and its association with peripheral anterior chamber depth in a defined population in Northern 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.
Intervention: After the screening examination, subjects with suspected glaucoma were re-examined at the screening center to confirm the diagnosis. All cases that still proved suspect after the second examination underwent a third phase of investigations and were classified as healthy or as definitely glaucomatous. Each subject was examined according to a standard protocol, including medical history interview, refraction and visual acuity determination, ocular biomicroscopy, evaluation of peripheral anterior chamber depth by means of the Van Herick method, applanation tonometry, optic disc evaluation, and computerized perimetry. Gonioscopy was not performed during initial screening but only in all selected patients in the second and third phases 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 > or = 22 mmHg, glaucomatous optic disc abnormalities, glaucomatous visual field defects. In addition, biomicroscopic or gonioscopic evidence of angle closure was also necessary.
Main outcome measures: Percentage distribution of peripheral anterior chamber depths, prevalence of angle-closure glaucoma, and frequency of the different PACG clinical presentations.
Results: Four thousand two hundred ninety-seven subjects were examined (73.9% overall participation rate). The peripheral depth of the anterior chamber 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-closure glaucoma was 0.6% (26 cases). Five of these were cases of previous acute attacks resolved by therapy, three were cases of chronic angle-closure after 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 populations previously studied. The prevalence of PACG is not as low as is usually 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.