Wise and Witter published in 1979 the results of argon laser treatment of glaucoma simplex. They coagulated in and just behind the trabeculum using as little energy as possible (+/- 100 coagulations, 50 mu, 1/10 sec, 80-1500 mWatt, spaced over 360 degrees). As we consider that coagulation of the trabeculum is not entirely without risk, we modified the technique by placing the lesions in the scleral spur. Up to the end of 1981, 84 eyes had been treated in 69 patients. Of 28 eyes in which treatment had taken place at least 1 year ago, the results in twenty-five were able to be analysed. The average decrease in pressure one year after treatment was 6.5-8.5 mm Hg (+/- 30% of the original value). The coefficient of outflow was measured in 10 eyes before and after treatment. This rose from an average of 0.11 (+/- 0.03) to an average of 0.18 (+/- 0.02).