Pressure-curve variations after trabeculectomy for chronic primary open-angle glaucoma. We report the results of a 5-year study of the influence of trabeculectomy on the maximum intraocular pressure (IOP) and the amplitude of its diurnal oscillation in 26 eyes (14 patients) with open-angle glaucoma. Pressure-curves were recorded before surgery and at 1 year and 5 years after surgery. The latter two pressure-curves demonstrated that trabeculectomy significantly reduced both the maximum IOP and the amplitude of the oscillations below preoperative values. 