This review article considers primary angle-closure glaucoma which is responsible for half of glaucoma-related blindness worldwide. Angle closure is characterised by appositional contact between the iris and trabecular meshwork. It tends to develop in eyes with shallow anterior chambers, anteriorly positioned or pushed lenses, and angle crowding. Risk of primary angle-closure glaucoma is high among women, the elderly and the hyperopic, and it is most prevalent in Asia. Investigation into genetic mechanisms of glaucoma inheritance is ongoing. Diagnosis relies on gonioscopy and may be supplemented by anterior segment optical coherence tomography and ultrasound biomicroscopy. Treatment is aimed to control intraocular pressure while monitoring changes to the angle and optic nerve head. Treatment typically begins with medical management through pressure reducing topical medications. Peripheral iridotomy is often performed to alleviate pupillary block, while laser iridoplasty has been found effective for mechanisms of closure other than pupillary block, such as plateau iris syndrome. Phacoemulsification, with or without goniosynechialysis, endoscopic cyclophotocoagulation and trabeculectomy remain other treatment options.