Laser Trabeculoplasty

Glaucoma is defined to be a progressive optic neuropathy that can lead to irreversible blindness. There are various known risk factors for glaucoma. However, intraocular pressure (IOP) appears to be the only known modifiable risk factor for control of the onset and progression of optic neuropathy. Besides the medical and surgical therapy for glaucoma, laser treatment has received considerable attention as an effective modality in recent times. Laser trabeculoplasty commonly practiced are argon laser trabeculoplasty (ALT) and selective laser trabeculoplasty (SLT) to increase aqueous humor outflow and thus lower intraocular pressure. Wise and Witter described the first protocol for ALT in 1979. They demonstrated the safety and efficacy of ALT in a group of patients with open-angle glaucoma (OAG). ALT's safety and long-term efficacy were studied in the glaucoma laser trial. In the glaucoma laser trial, eyes receiving 360° ALT were compared with medical monotherapy with a follow-up period of  2.5 to 5.5 years, concluding that trabeculoplasty was as efficacious as medical therapy in reducing intraocular pressure. However, ALT did not become primary therapy in patients with primary open-angle glaucoma (POAG) because of reduced efficacy over time, so it was used as an adjunctive therapy. Laser trabeculoplasty gained popularity with SLT. SLT uses a Q-switched frequency-doubled Nd: YAG laser in the trabecular meshwork, which appears less destructive than ALT. However, it has been noticed that both ALT and SLT are equally efficacious in reducing intraocular pressure in OAG.