Epidemiologic approach to open-angle glaucoma: 1. Control of intraocular pressure. Report of the Canadian Ocular...

In a multicentre study eight glaucoma consultants prospectively followed 71 unselected cases (130 eyes) of newly diagnosed open-angle glaucoma at five visits over a mean interval of 12.1 months. A standard flow chart was used to record the medical treatment, intraocular pressure (IOP) and indications for any changes in therapy. No limitations were imposed on the choice of drugs. The mean IOP before treatment was 28 mm Hg. There was a significant reduction in mean IOP of 7.64 mm Hg in response to the first drug prescribed (p less than 0.0001) but none thereafter, despite changes in treatment in 25% to 32% of eyes at each visit. The mean standard deviation of IOP for all eyes was 2.62 mm Hg. Of 99 changes in therapy in 67 eyes, 40% were made when the IOP was within 3 mm Hg of the mean satisfactory pressure for a particular case. The findings indicate the need to make corrections for variation and fluctuation in IOP when evaluating pressure response. The pharmacologic effect of the drugs appeared less important than the patient's ability to tolerate the drugs without severe adverse reactions.