Abstract
Purpose: :
To compare the efficacy of Selective Laser Trabeculoplasty (SLT) to reduce intraocular pressure (IOP) in patients with early open angle glaucoma (OAG) versus patients with moderate to severely advanced OAG, and to determine the rates of subsequent glaucoma surgical intervention in each group over a 5 year period in a tertiary glaucoma referral practice.
Methods: :
This is a retrospective chart review of 75 eyes of 75 consecutive patients with open angle glaucoma who underwent secondary SLT (180 degrees) between December 2001 to December 2003 for inadequately controlled intraocular pressure. Patients were classified at the time of the SLT to have early disease (Group I), if the mean defect on the Humphrey visual field test (24-2 program) was < 6dB, while patients were classified as having moderate to severely advanced disease (Group II) if the mean defect was ≥ 6 dB. Patients were followed for a maximum of 5 years or until the time of glaucoma surgical intervention. Success rates (defined as no surgical intervention) between the two groups were compared using Kaplan-Meier survival curves at 2 and 5 yrs. The mean IOP and the number of medications pre-SLT and post-SLT were determined in each group.
Results: :
There were 44 patients in Group 1 (mean 70.1 yrs) and 31 patients in group II (mean 72.8 yrs). The mean pre-laser IOP was 21.8 (±4.1) mm Hg in Group I, and 22.2 (±5) mm Hg in Group II (P=0.54), with a mean post-laser IOP drop of 3.9 (±1.9) mm Hg in Group I and 3.1 (±1.3) mm in Group II (P=.08). The mean number of glaucoma medications increased by 0.18 in Group I as compared to 0.09 in Group II (P=0.8). These differences were not significant at the P<0.05 level. Success at 2 yrs and 5 yrs for group I was 88.6% and 81.7% respectively, vs. 56.5% and 34.2% for group II (P<.001).
Conclusions: :
The magnitude of IOP reduction after SLT was similar in patients with early OAG and moderate /severe OAG. However, in patients with moderate/severe OAG, the rate of glaucoma surgery following SLT was significantly greater compared to patients with early OAG. This suggests that despite similar efficacy of SLT to reduce IOP in the two groups, patients with moderate/severe OAG are less likely to achieve target IOP’s required to prevent surgical intervention.
Keywords: laser • intraocular pressure • clinical (human) or epidemiologic studies: outcomes/complications