Purpose: To compare the intraocular pressure lowering effect of selective laser trabeculoplasty (SLT) and argon laser trabeculoplasty (ALT) in medically uncontrolled open-angle glaucoma patients.
Methods: This was a randomized, parallel-group, clinical trial. A total of 50 consecutive glaucoma patients with inadequate medical control of intraocular pressure (IOP) were screened and randomized to treatment with either SLT or ALT: 25 patients were treated with SLT using the Coherent Selecta 7000 (Q-switched, frequency doubled, 532 nm Nd:YAG laser) and 25 patients underwent ALT using the Coherent 900 Argon blue-green laser. The SLT group received 50 to 70 non-overlapping spots over 360° with a pulse energy level ranging from 0.8 to 1.2 mJ avoiding cavitation bubble formation. ALT was performed to 360° using 80 to 100 applications at 0.1 second/50 micron/600-800 mW to cause blanching and/or cavitation bubbles formation. All patients were evaluated at 1 hour, 2 weeks, 1,3,6,12 months post-laser.
Results: Mean IOP reductions following SLT and ALT were 5.3+/-1.5 mmHg (22.8%) vs 5.0+/-2.1 mmHg (21.8%) (p=0.58) at 6 months and 5.2+/-1.5 mmHg (22.4%) vs 4.7+/-1.7 mmHg (20.5%) (p=0.26) at 1 year of follow up. Patients with previous failed ALT had a better reduction in IOP with SLT than with repeated ALT. Compared with the ALT group, the SLT group showed an higher incidence of anterior chamber reaction and IOP spike.
Conclusions: Our results suggest that SLT is equivalent to ALT in lowering IOP during the first year after treatment. SLT appears more effective than ALT in patients who have had previuos ALT.