The primary aim of the study is to determine whether argon laser peripheral iridoplasty (ALPI) is an effective treatment in terms of intraocular pressure (IOP) control for cases of primary angle closure glaucoma (PACG) in which the drainage angle remains narrow following laser iridotomy. Primary outcome measures will be the proportion of patients requiring medical or surgical treatment to maintain IOP control, number of medications required to control IOP at 12 months follow up.