Should we perform peripheral laser iridotomy in primary angle closure suspects: implications of the ZAP trial?

Glaucoma is the leading cause of irreversible blindness globally. The morbidity due to disease is also quite high with an estimated 3.5% of population aged 40–80 years suffering from glaucoma (1,2). Broadly two types of primary glaucomas are identified, primary open angle glaucoma (POAG) and primary angles closure glaucoma (PACG). Angle closure glaucomas constitute a spectrum that include primary angle closure suspects (PACS, occludable angles), persons with primary angle closure (PAC, occludable angles with features indicative of trabecular outflow obstruction but absence of glaucomatous optic neuropathy) and finally PACG (presence of glaucomatous optic neuropathy). PACG is responsible for 31% of all cases globally, but the proportion has been reported to be higher in Asia at 40% (2). Data from population based studies in Asia show that PACG causes greater proportion of blindness than POAG (3)