Immediate treatment halves risk of open-angle glaucoma progression, EMGT report reveals

Cheryl Guttman
in Stony Brook, New York

CRUCIAL new data from the Early Manifest Glaucoma Trial (EMGT) has shown that immediate treatment can halve the risk of progression in early open-angle glaucoma, while higher intraocular pressure (IOP) and old age are among a host of significant factors linked to the progression of the disease.

Christina Leske

The latest information adds to the initial results from the trial, which demonstrated the benefits of immediately treating early glaucoma. Researchers from the EMGT group evaluated more than 20 ocular, medical and family history, demographic, and follow-up variables as risk factors for glaucoma progression.

In addition to the benefit of immediate treatment, the analysis found that higher IOP, exfoliation, bilateral disease, worse perimetric mean deviation and older age at baseline were all statistically significant and independent factors influencing disease outcomes.
In addition, the magnitude of initial IOP reduction and the frequency of disc haemorrhages observed during follow-up visits were also independent risk predictors of glaucoma progression.

And all of these factors should be considered in the management decisions made for patients with early glaucoma, Director of the EMGT Data Centre, M Cristina Leske MD, MPH, said. She is also the lead author of a recently published paper outlining the results. [Archives of Ophthalmology 2003;121:48-56].

Based on the initial report, which showed that progression occurred in 45% of treated patients and 62% of controls, some observers argued the treatment benefit was not that significant.

Baseline factors related to progression.

Follow-up factors related to progression.

Dr Leske explained that the current analyses quantify the magnitude of the treatment benefit while controlling for other factors.

She said that considering these results and the perimetric method used to identify progression, which is highly sensitive for identifying early change, the benefit of immediate treatment is “quite striking”.

“While these analyses reinforce the conclusion that immediate treatment is beneficial and supports the theory that reducing IOP decreases the risk of progression, they should not be taken to mean that all patients with early glaucoma require immediate treatment.

“In the EMGT there was a very wide range of progression rates and some untreated controls have shown no progression over years of follow-up. Therefore, the current results support the value of individualised glaucoma management. Clinicians need to consider each patient, assess the profile of risk factors, and decide on treatment accordingly,” Dr Leske explained.

In the multivariate analyses to identify risk factors for progression, the variables which had the greatest effect and doubled progression risk were exfoliation (2.2-fold increase) and the presence of two eyes eligible for the study (1.96-fold increase).

Additionally, patients whose IOP at baseline was at or above the median had a 1.7-fold increased risk of progression. Both a baseline mean deviation worse than the median value and an age older than the population median had approximately a 1.5-fold increased risk of progression.

After randomisation, the first follow-up visit occurred three months later. Analyses based on the IOP change from baseline at that visit showed that each millimetre of mercury of IOP reduction meant a 10% decrease in the risk of progression.

Consistent with that finding, IOP at the three-month visit mark and mean IOP during follow-up were also significant prognostic indicators. At each visit, the examining ophthalmologist recorded the absence or presence of disc haemorrhage, and for each patient a value was calculated representing the proportion of total visits at which a clinically identified disc haemorrhage was present.
For each additional percentage point of visits with a disc haemorrhage, the risk of progression increased by 2%.

Dr Leske pointed out that the study’s design was unique in several characteristics that particularly qualified it to evaluate potential risk factors for progression. The EMGT enrolled patients with early disease — the majority of whom had been identified from population-based screening — and prospectively randomised them to treatment or observation with close follow-up every three months. It was also rigorously conducted with excellent retention rates and visit compliance rates.

“Other major glaucoma clinical trial studies compared two kinds of treatment and therefore their results could not be used to quantify exactly how effective is IOP-lowering treatment.

“The long-term follow-up of randomised patients using a standard protocol and the comprehensive data collection are positive aspects of the trial. These and other study features strengthen our results and conclusions,” Dr Leske said.

M Cristina Leske MD, MPH
Stony Brook University, New York, US
Email: cleske@notes.cc.sunysb.edu

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