Factors for Glaucoma Progression and the Effect of Treatment: The Early Manifest Glaucoma Trial

Abstract

OBJECTIVE: To assess factors for progression in the Early Manifest Glaucoma Trial (EMGT), including the effect of EMGT treatment. SETTING/PARTICIPANTS: Two hundred fifty-five open-angle glaucoma patients randomized to argon laser trabeculoplasty plus topical betaxolol or no immediate treatment (129 treated; 126 controls) and followed up every 3 months. METHODS: Progression was determined by perimetric and photographic optic disc criteria. Patient-based risk of progression was evaluated using Cox proportional hazard regression models and was expressed as hazard ratios (HR) with 95% confidence intervals (95% CI). RESULTS: After 6 years, 53% of patients progressed. In multivariate analyses, progression risk was halved by treatment (HR = 0.50; 95% CI, 0.35-0.71). Predictive baseline factors were higher intraocular pressure (IOP) (ie, the higher the baseline IOP, the higher the risk), exfoliation, and having both eyes eligible (each of the latter 2 factors doubled the risk), as well as worse mean deviation and older age. Progression risk decreased by about 10% with each millimeter of mercury of IOP reduction from baseline to the first follow-up visit (HR = 0.90 per millimeter of mercury decrease; 95% CI, 0.86-0.94). The first IOP at that visit (3 months' follow-up) was also related to progression (HR = 1.11 per millimeter of mercury higher; 95% CI, 1.06-1.17), as was the mean IOP at follow-up (HR = 1.13 per millimeter of mercury higher; 95% CI, 1.07-1.19). The percent of patient follow-up visits with disc hemorrhages was also related to progression (HR = 1.02 per percent higher; 95% CI, 1.01-1.03). No other factors were identified. CONCLUSIONS: Patients treated in the EMGT had half of the progression risk of control patients. The magnitude of initial IOP reduction was a major factor influencing outcome. Progression was also increased with higher baseline IOP, exfoliation, bilateral disease, worse mean deviation, and older age, as well as frequent disc hemorrhages during follow-up. Each higher (or lower) millimeter of mercury of IOP on follow-up was associated with an approximate 10% increased (or decreased) risk of progression.