This is a clinical trial to evaluate the effect of immediate reduction of intraocular pressure (lOP) vs. no treatment, on progression of early open-angle glaucoma (OAG), initiated in 1993. The trial randomized OAG patients to immediate lOP-lowering treatment vs. no initial treatment. EMGT-2 proposes to continue following these patients to determine the long-term effects of treatment, as well as to evaluate patterns of progression and their related factors. This unique, well-defined cohort now has an average follow-up time of 7 years and includes a wide spectrum of disease. An additional 4.5 yrs of data collection in EMGT-2 with the same protocol would provide at least 11 years of observation for all patients, with an average follow-up time of about 12.5 years. Methods in EMGT-2 will remain the same as in the first phase except that:1) study visits will be reduced from quarterly to semiannual; and, 2) Heidelberg Retina Tomograph (HRT-II) images will be used to evaluate disc changes. Feasibility is enhanced because of the excellent retention in both study groups: of the 255 EMGT patients, 32 have died and only 9 (4%) have been losses to follow-up. The primary aims of EMGT-2 are: 1- To determine, through a series of subaims, the frequency and trends of long-term ocular and general outcomes (e.g., visual field (VF), cataract, mortality, visual function-related quality of life) of glaucoma patients randomized to immediate treatment or no treatment; 2- To evaluate and quantify the independent effect of EMGT treatment and other factors on long-term progression (e.g., extent of initial lOP reduction and at follow-up; disease severity; disc hemorrhages; corneal thickness, systemic variables); and 3- To evaluate and compare the rates of glaucoma-related changes in VF and discs, based on Humphrey C30-2 threshold tests and HRT-II images. Secondary aims are: 1) To obtain long-term natural history data on control patients who remain untreated; 2) To determine the development of glaucoma-related changes in fellow eyes of patients who had only one initially eligible eye; and 3) To describe the temporal and spatial distribution of disc hemorrhages and their relationship to other indicators of glaucoma damage. EMGT-2 will continue to follow the same clinical trial design and protocol. Specific outcomes for each aim have been defined. Estimates indicate that EMGT-2 analyses will have sufficient power to meet the proposed aims. This application seeks continued support for the activities of the Data Center for EMGT-2. A separate application seeking support for the activities of the Clinical Center has also been submitted. [unreadable] [unreadable] [unreadable] [unreadable] [unreadable]