PURPOSE: Glaucoma is the second cause, after cataract, of world blindness. Approximately half is thought to be primary angle-closure glaucoma (ACG). This review asks whether ACG can be prevented on a population basis. METHODS AND POPULATIONS: Review of published information from the Inuit of Greenland, Canada and Alaska, and descriptions of recent studies in Asian populations in Mongolia, China and South-East Asia. RESULTS: The Greenland Inuit have the shallowest anterior chamber depths (ACDs) so far recorded. The proportion of blindness due to ACG was reduced from 64% to 9% over 37 years by systematic optical measurement of central ACD and the van Herick test in the older Inuit, followed by gonioscopy and prophylactic iridectomy or laser iridotomy when indicated. In Mongolia, ultrasound measurement of central ACD had good sensitivity and specificity as a screening test. A randomized controlled trial of screening and prophylactic laser is being completed. In China and South-East Asia, the mechanism of angle closure appears to be more varied and complex and its detection may require more elaborate imaging. CONCLUSIONS: The mechanism of angle closure and potential for prevention by screening are likely to have to be determined specifically for each population at risk.