A Comparison of the Intervisit Intraocular Pressure Fluctuation After 180 and 360 Degrees of Selective Laser Trabeculoplasty (SLT) as a Primary Therapy in Primary Open Angle Glaucoma and Ocular Hypertension

Objective: To determine and compare the effect of 180 and 360 degrees of selective laser trabeculoplasty (SLT) treatment as a primary therapy on the intervisit intraocular pressure (IOP) fluctuation in patients followed up for a period of 2 years without any further medical or surgical intervention. Methods: Retrospective chart review of patients with ocular hypertension and primary open angle glaucoma who received SLT as primary therapy without any subsequent medical or surgical intervention. IOP before SLT and postlaser IOP at all the visits during the follow-up period of months 6 to 24 was determined. The standard deviation (SD) of the mean IOP? was used as a surrogate for IOP fluctuation. Results: Forty-one eyes were treated by SLT, 19 eyes in the 180-degree group and 22 eyes in the 360-degree group. The mean reduction in IOP at 2 years was 28% in 180-degree group and 35% in 360-degree SLT group. After the SLT, the 360-degree SLT group had a lower IOP fluctuation compared with the 180-degree SLT group over the follow-up period of months 6 to 24. The percentage of eyes with intervisit IOP fluctuation (SD) <= 2 mm Hg during the same follow-up period was significantly greater in 360-degree SLT treatment group (86%) than in the 180-degree SLT treatment group (52%), P = 0.03. The odds of achieving IOP fluctuation <= 2 man Hg were 5.7 times greater with 360 degrees than with 180-degree SLT during the follow-up period of months 6 to 24. Conclusions: This study suggests that 360-degree SLT is more efficacious in achieving smaller IOP fluctuations than treatment with 180-degree SLT.