To determine progression factors at the end of the Early Manifest Glaucoma Trial (EMGT)
based on all EMGT patients and evaluate separately patients with higher and lower
baseline intraocular pressure (IOP; median split).
Cohort of clinical trial participants.
Patients with early open-angle glaucoma randomized to argon laser trabeculoplasty
plus betaxolol (n = 129) or no immediate treatment (n = 126), examined every 3 months
for up to 11 years.
Cox proportional hazard analyses, expressed by hazard ratios (HRs) and 95% confidence
intervals (CIs).
Time to progression, defined by perimetric and photographic disc criteria.
Overall progression was 67% when follow-up ended (median, 8 years). Treatment approximately
halved progression risk (HR, 0.53; 95% CI, 0.39-0.72); results were similar for patients
with higher and lower baseline IOP (HRs, 0.41 and 0.55). Baseline progression factors
(HRs, 1.51-2.12; P<0.01) were higher IOP, exfoliation, bilateral disease, and older
age, as previously reported. New baseline predictors were lower ocular systolic perfusion
pressure in all patients (< or =160 mmHg; HR, 1.42; 95% CI, 1.04-1.94), cardiovascular
disease history (HR, 2.75; 95% CI, 1.44-5.26) in patients with higher baseline IOP,
and lower systolic blood pressure (BP) (< or =125 mmHg; HR, 0.46; 95% CI, 0.21-1.02)
in patients with lower baseline IOP. Postbaseline progression factors were IOP levels
at follow-up, with 12% to 13% average increase per millimeter of mercury in all patients
(HRs, 1.12-1.13 per mmHg higher) and similar results in patients with higher and lower
baseline IOP (HRs, 1.15 and 1.13 per mmHg higher). Disc hemorrhages (HR, 1.02; 95%
CI, 1.01-1.03 per percent higher frequency) also predicted progression. Thinner central
corneal thickness (CCT) (HR, 1.25; 95% CI, 1.01-1.55 per 40 microm lower) was a new
significant factor, a result observed in patients with higher baseline IOP (HR, 1.42;
95% CI, 1.05-1.92 per 40 microm lower) but not lower baseline IOP, with significant
IOP-CCT interaction.
Treatment and follow-up IOP continued to have a marked influence on progression, regardless
of baseline IOP. Other significant factors were age, bilaterality, exfoliation, and
disc hemorrhages, as previously determined. Lower systolic perfusion pressure, lower
systolic BP, and cardiovascular disease history emerged as new predictors, suggesting
a vascular role in glaucoma progression. Another new factor was thinner CCT, with
results possibly indicating a preferential CCT effect with higher IOP.