Argon laser trabeculoplasty (ALT) and selective laser trabeculoplasty (SLT) are effective treatment modalities for intraocular pressure (IOP) lowering in open angle glaucoma patients. SLT and ALT produce equivalent IOP reduction. The choice of either option will depend on the state of glaucoma, previous and current treatment, side effects and patient's reference. Preservation of the angle trabecular meshwork structures and effective retreatment for IOP lowering after ALT has failed, offer some theoretical advantage of SLT.