Selective Laser Trabeculoplasty, or SLT, is a form of laser surgery that is used to lower intraocular pressure in glaucoma. It is used when eye drop medications are not lowering the eye pressure enough or are causing significant side effects.It may sometimes be used as initial treatment in glaucoma. Who is a candidate for SLT? 2  Patients who have open-angle glaucoma (the drainage system in the front part of the eye is open) and are in need of lowering of their intraocular pressure (IOP) are eligible for the procedure. 3  Your eye doctor will make the final determination if you are a candidate.