Yag iridotomy is the preferred procedure for treating angle-closure glaucoma caused by relative or absolute pupillary block. It eliminates pupillary block by allowing the aqueous to pass directly from the posterior chamber into the anterior chamber, bypassing the pupil. It can be performed by only NDYAG laser, with neodymium: yttrium-aluminum-garnet (Nd: YAG) laser, or, in certain circumstances, with both.