Laser trabeculoplasty — argon or diode?*

Abstract

It is important to compare the pressure‐lowering effect of the recently introduced diode laser with that of the argon laser currently used for trabeculoplasty, since there is a considerable difference in their wavelengths. In 50 consecutive eyes of 50 patients argon laser trabeculoplasty (ALT) produced a fall from 23 to 18 mmHg at three months compared with a fall from 23 to 19 mmHg at three months with diode laser trabeculoplasty (DLT). This difference was not statistically significant. Comparing the magnitude of the fall in intraocular pressure (IOP) in these two groups of 50 eyes, 28 patients achieved a fall of 5 mmHg or more with ALT and 17 with DLT and this difference was significant (χ2 1df=4.04, P<0.05). Comparing 23 paired fellow eyes which both needed laser trabeculoplasty, those treated with ALT achieved a fall from 22 to 17 mmHg compared with a fall from 22 to 19 mmHg with DLT and this difference was statistically significant (T = 53.5, P<0.02, Wilcoxon matched‐pairs signed rank test). These results suggest that the pressure lowering effect of DLT is comparable to that of ALT, but ALT is somewhat more effective as shown by a greater fall in IOP after ALT than DLT in fellow eyes of the same patient. In the unpaired eyes the number of falls of 5 mmHg or more was significantly greater with ALT than DLT, although the mean fall was not statistically different between the two groups.