Pattern of intraocular pressure reduction following laser trabeculoplasty in open-angle glaucoma patients: comparison between selective and nonselective treatment

OBJECTIVE: To compare the pattern of intraocular pressure (IOP) reduction following selective laser trabeculoplasty (SLT) versus argon laser trabeculoplasty (ALT) in open-angle glaucoma (OAG) patients, and to investigate the ability of initial IOP reduction to predict mid-term success. METHODS: A prospective, nonrandomized, interventional case series was carried out. Consecutive uncontrolled OAG glaucoma patients underwent SLT or ALT; the same preoperative medical regimen was maintained during follow-up. Data collected included age, type of OAG, pre- and postoperative IOP, number of glaucoma medications, and surgical complications. Post-treatment assessments were scheduled at day 1 and 7 and months 1, 3, and 6. RESULTS: A total of 45 patients (45 eyes) were enrolled [SLT group (n = 25); ALT group (n = 20)]. Groups were similar for age, baseline IOP, and number of glaucoma medications (P ≥ 0.12). We found no significant differences in mean IOP reduction between SLT (5.1 ± 2.5 mmHg; 26.6%) and ALT (4.4 ± 2.8 mmHg; 22.8%) groups at month 6 (P = 0.38). Success rates (IOP ≤ 16 mmHg and IOP reduction ≥25%) at last follow-up visit were similar for SLT (72%) and ALT (65%) groups (P = 0.36). Comparing the pattern of IOP reduction (% of IOP reduction at each visit) between groups, we found a greater effect following SLT compared with ALT at day 7 (23.7% ± 13.7% vs 8.1% ± 9.5%; P < 0.001). No significant differences were observed at other time points (P ≥ 0.32). Additionally, the percentage of IOP reduction at day 7 and at month 6 were significantly correlated in the SLT group (R(2) = 0.36; P < 0.01), but not in the ALT group (P = 0.89). Early postoperative success predicted late success in most SLT cases (82%). No serious complications were observed. CONCLUSION: Although mid-term results suggest SLT and ALT as effective and equivalent alternatives, a greater initial IOP reduction was observed following SLT. In addition, the initial IOP reduction was a good predictor of mid-term success in patients undergoing SLT, but not ALT.