PURPOSE: To evaluate long-term risk factors for progression or stability in patients with primary open-angle glaucoma.

METHOD: We retrospectively included consecutively reviewed patients who had primary open-angle glaucoma for at least 5 years in this multicenter trial. Historical and clinical factors in these patients were evaluated for their association with stability or progression of the glaucoma.

RESULTS: We included 218 patients in this study; of these, 34 progressed over an average length of follow-up of 45.5 ± 30.0 months, and 184 were stable over an average of 72.8 ± 18.3 months. The mean intraocular pressure over the follow-up period for the progressed group was 19.5 ± 3.8 mm Hg and for the stable group 17.2 ± 3.1 mm Hg (P = .001). The average standard deviation of individual intraocular pressures was greater in the progressed group (5.1 mm Hg) than the stable group (3.9 mm Hg, P = .012). Baseline characteristics indicating a greater potential to progress were a larger cup-to-disk ratio (P < .001), a greater number of medications (P = .02), older age (P .007), and worse visual acuity (P = .003). However, no difference was observed in pressure levels that prevented progression in these subpopulations compared with the total sample size.

CONCLUSIONS: This study suggests that lowering the intraocular pressure is important in the treatment of primary open-angle glaucoma to help prevent long-term progression. Lowering the pressure, however, is not uniformly effective in preventing progression. Additionally, risk factors for progression do not further help identify pressure levels that prevent worsening of glaucoma.