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Study: Most glaucoma patients under routine care show slow progression
In a study to investigate the rate of glaucomatous visual field change in clinical care, researchers found the mean deviation rate to increase with age.
Additionally, Chauhan and colleagues noted in Investigative Ophthalmology & Visual Science that slow rates of visual field progression were seen in the majority of patients under routine glaucoma care.
Researchers used mean deviation (MD) calculations from one eye of 2,324 patients with at least five visual field examinations and analyzed MD in tertile groups by baseline age, the number of examinations and MD, as detailed in the study.
"There were 2,324 patients with median (interquartile range, IQR) baseline age and MD of 65 (56, 74) years and -2.44 (-5.44, -0.86) dB and follow-up of 7.1 (4.8, 10.2) years with eight (six, 11) examinations," the authors reported. "The median MD rate was -0.05 (0.13, -0.30) dB/y, [with a] mean follow-up IOP of 17.1 (15.0, 19.7) mm Hg."
Results showed that as age increased, the MD rate was progressively worse. A worse MD rate was also associated with a lower follow-up IOP, according to the study.
"In a large group of patients, not enrolled in research studies and followed for routine glaucoma care, we found the average rate of visual field change to be slow," the authors concluded. "We were unable to demonstrate meaningful differences in MD rates between these patients and those in a prospective interventional study, after matching patients pairwise for the amount of visual field loss. Finally, after matching patients to those from a recent study with a similar design, the MD rates in the current study were significantly less negative."
Perspective
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It is difficult to apply study results to clinical practice. The essence of patient individuality, which can be tempered in a study, is integral in the clinical decision making process in glaucoma management. Chauhan et al. examine visual field progression in glaucoma patients in a way that effectively removes this selection bias, providing a more real-world outlook on the state of contemporary glaucoma care.
In analyzing data from patients in their specialty clinic, they were able to sample the full range of patient dynamics (i.e., poor visual field testers, poor follow-up compliance, etc.). The only criterion for inclusion was that the patients had at least five visual fields and were either glaucoma suspects or had glaucoma. Using mean deviation as the metric for visual field progression, they found that the rate of loss did not differ between their glaucoma patients and patients enrolled in the Canadian Glaucoma Study.
Chauhan’s study suggests that although dynamics differ between routine glaucoma patients vs. patients enrolled in a clinical trial, the care delivered provides similar visual field outcomes. This provides reassurance that contemporary glaucoma care practices are effective at limiting visual field loss, despite the possible selection bias that exists in the studies upon which they are based.
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Chauhan BC, et al. Invest Ophthalmol Vis Sci. 2014; doi: 10.1167/iovs.14-14643.