Longer follow-up data shed more light on risk factors for glaucoma progression

Ongoing analysis of data from the Early Manifest Glaucoma Trial (EMGT) has shown that positive cardiovascular history and thinner central corneal thickness increase the risk of progression, but only in patients with higher baseline IOP. Low blood pressure emerged as a risk factor in normal-tension glaucoma.

Key Points

New Orleans-Longer follow-up data from the Early Manifest Glaucoma Trial (EMGT) are shedding even more light on the risk factors for glaucoma progression.

The EMGT was begun in 1993 as a prospective study to evaluate the effects of early intervention. The initial report from this study, published in 2002, demonstrated that early intervention slowed progression of open-angle glaucoma. Now that follow-up has continued considerably longer, more information is available on risk factors for progression, said Anders H. Heijl, MD, PhD, who presented updates and clinical pearls from the EMGT during a glaucoma subspecialty day talk here at the annual meeting of the American Academy of Ophthalmology.

One of the key messages learned from the EMGT is that treatment is effective and reduces the risk of glaucoma progression considerably. But although IOP is a very important factor for progression, IOP fluctuation is not an independent risk factor, said Dr. Heijl, professor of ophthalmology, University of Lund, Malmö, Sweden, and chairman, Department of Ophthalmology, Malmö University Hospital. He and fellow investigators found that exfoliation is a strong and independent risk factor and that a positive cardiovascular history and thinner central corneal thickness (CCT) increase risk, but only in patients with higher baseline IOP. Low blood pressure is a risk factor in normal-tension glaucoma.

The EMGT is the only randomized trial of patients with primary open-angle glaucoma, normal-tension glaucoma, and pseudoexfoliation glaucoma that included an untreated control group. The trial recruited 255 patients between 1993 and 1997. They were randomly assigned to a fixed treatment protocol of betaxolol (Betoptic, Alcon Laboratories) plus argon laser trabeculoplasty (ALT) or no treatment. Patients were monitored every 3 months for signs of advancing disease; therapy did not change unless progression occurred.

The study was a collaborative effort involving the University of Lund, Lund, Sweden, with clinical centers in Malmö and Helsingborg, Sweden, and a data center at Stony Brook University, Stony Brook, NY.

The risk factors for progression, first reported in 2003, were based on patients with at least 4 years of follow-up. The significant risk factors were higher IOP, older age, pseudoexfoliation, more visual field damage, and disk hemorrhages. No systemic risk factors were found, and CCT was not a risk factor. An updated analysis subsequently was performed, based on the situation at the end of 2004 when all patients had been in the study between 7 and 11 years, Dr. Heijl said.

The evaluation included treatment assignment and demographic factors such as age and sex. Ocular factors included IOP, number of eligible eyes, mean deviation, exfoliation, refractive errors, disk hemorrhages, and CCT. The systemic factors were blood pressure; antihypertensive medications; systolic, diastolic, and mean perfusion pressure; cardiovascular disease; Raynaud's disease; migraine; and smoking. Family history of glaucoma also was assessed.

At the end of follow-up in 2004, the median follow-up time was 8 years. During that period, disease in 67% of patients had progressed (in 59% of the treated group versus 76% of the controls). The median time to progression was 60 months (67 months in treated patients and 49 months in controls).