Purpose:
Intraocular pressure (IOP) fluctuation has been shown to be an important risk factor for visual field progression in glaucoma. This study evaluated the degree of intervisit IOP fluctuation in patients treated with SLT as primary therapy for open angle glaucoma and compared efficacy of 180 vs 360 degree treatment on post–laser IOP fluctuation.
Methods:
This is a retrospective study of 73 eyes of 45 patients, with POAG or OHT, who underwent SLT treatment either 180 degrees (36 eyes) or 360 degrees (37 eyes) with 1 year follow–up without any additional medical or surgical therapy. IOP was measured at 2–4 weeks, 2–4, 6, 9, and 12 months post–op. The standard deviation (SD) of the mean post–treatment IOP was used as a surrogate for IOP fluctuation. Mean post–treatment IOP for each treated eye was determined for the entire follow–up period, and for month 6 to month 12 follow–up period (to account for early post–treatment IOP response). Post–treatment IOP fluctuation for 360 vs 180 degree treatments were also compared. The number of eyes with IOP fluctuation 0–1.5 SD and greater than 1.5 SD were determined.
Results:
Mean pre–laser IOP for all eyes was 24.7 ± 2.9 mm Hg, and mean post–laser IOP at 1 year was 17.1 ± 2.3 or 30.7% reduction. SD ranged from 0 to 3.5 for the entire follow up period, and 0 to 3.7 for follow–up month 6 to month 12. A comparison of the number of eyes (%) with SD post–treatment < 1.5 mm Hg for 180 vs. 360 degrees treatment, and the entire F/U period vs. month 6 to month 12 F/U period, is shown in the table below.
Conclusions:
A majority of patients treated with SLT as primary therapy with 1 year F/U show IOP fluctuations of < 1.5 mm Hg SD. The percentage of patients with IOP fluctuations of < 1.5 mm Hg SD were greater with 360 degrees treatment and a F/U period beyond 6 months. This indicates IOP fluctuation was greater in the early post–op period and lessened at longer follow–up periods. The data also suggests that a 360 degree treatment is associated with a greater proportion of eyes with smaller long–term IOP fluctuation (SD < 1.5 ), compared to 180 degrees of treatment (p=.04).
Keywords: trabecular meshwork • intraocular pressure • laser