Diode laser trabeculoplasty versus argon laser trabeculoplasty in the control of primary open angle glaucoma

A randomised prospective study was carried out to determine whether diode laser trabeculoplasty (DLT) is as effective as argon laser trabeculoplasty (ALT) in the control of primary open angle glaucoma (POAG). Forty eyes of 40 patients with uncontrolled intraocular pressure (IOP) despite maximum topical medication were entered into the study. Twenty eyes received DLT, spot size 100 mu m, exposure time 0.2 s, mean power 1034 (+/- 56.4) mW. Twenty eyes received ALT, spot size 50 mu m, exposure time 0.2 s, mean power 528 (+/- 44.7) mW. They were reviewed at 2 h, 2 and 8 weeks, and 3, 6, 12, 18 and 24 months after laser treatment. Two eyes were withdrawn from the DLT group and four from the ALT group because of uncontrolled IOP during follow-up. Of the remaining eyes in the trial, mean IOP reductions for DLT and ALT, respectively, were: 6 months 7.42 (+/-2.36) mmHg and 6.36 (+/-2.3)mmHg; 12 months 7.02 (+/-2.6)mmHg and 6.28 (+/-2.2)mmHg; 18 months 6.86 (+/-2.8)mmHg, 5.98 (+/-2.02)mmHg; 24 months 6.50 (+/-2.72)mmHg, 5.92 (+/- 2.02) mmHg. There was a significant reduction in each laser group when IOP at each stage was compared with baseline (p<0.001) (paired Student's t-test), but no significant difference between the two groups. In the ALT group peripheral anterior synechiae developed in four eyes and post laser pain in seven eyes. These complications were not noted following DLT. We conclude that DLT and ALT are equally effective in IOP control, but DLT is associated with less anterior segment inflammation.