To understand the natural history and the risk factors of primary angleclosure glaucoma and obtain experiences that might help screening for the disease.Four hundred and eighty-five suspects were screened from 6 548 population aged over 40 years. The suspects were then followed up within six years. The following examinations were performed: visual acuity, axial anterior chamber depth, peripheral anterior chamber depth, intraocular pressure and cup/disc ratio of optic nerve papilla. The suspects with high risk were further examined.During the follow-up period, twenty patients (4.1%) in the suspects developed angle-closure glaucoma, 14 cases had natural attack (Acute onset developed in 6 cases and 8 cases were in chronic stage) and 6 cases were found at early stage. The anterior chamber depth shallowed progressively in 28% of suspects.Anterior chamber depth is an important index for screening of primary angle-closure glaucoma, and the regular follow-up is of significance for the suspects.