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New glaucoma risk assessment tool helps identify patients in need of treatment
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CHICAGO — A handheld calculator designed to predict the risk of glaucoma progression in patients with ocular hypertension could change the standard of care for glaucoma specialists, according to one of its developers.
Robert N. Weinreb, MD, described the risk calculator at a press briefing sponsored by Pfizer Ophthalmics during the American Academy of Ophthalmology’s annual meeting.
“This is what we’ve all been waiting for — the ability to calculate the risk (of glaucoma progression) in individual patients,” Dr. Weinreb said.
He said the aim of the device is to determine which patients are at high, moderate and low risk for progressing to glaucoma from ocular hypertension and, of those who will go on to develop glaucoma, which ones are likely to sustain functional impairment.
“Our challenge is to identify patients at moderate to high risk for conversion from ocular hypertension to glaucoma and to direct therapy to those patients at high risk,” Dr. Weinreb said. “It is really about a better allocation of our resources.”
The risk calculator, which resembles a slide rule, was made available by Pfizer to attendees of the AAO and will be distributed to specialists worldwide by company representatives in the future. The research by Dr. Weinreb and colleagues that led to the development of the calculator was supported by Pfizer, according to the company.
In its current form, the device calculates risk based on a simplified version of a formula derived from findings in two independent study populations: the Ocular Hypertension Treatment Study and a subset of patients in the Diagnostic Innovations in Glaucoma Study at the Hamilton Glaucoma Center in San Diego, where Dr. Weinreb is director.
The physician assesses six factors for each hypertensive patient: age, baseline IOP, central corneal thickness, pattern standard deviation on perimetry, vertical cup-to-disc ratio and whether diabetes is present. These data are configured on the calculator using sliding tabs, and the combined result shows the calculated risk of glaucoma development in 5 years for that particular patient.
Because every specialist’s threshold of treatment is different, the risk calculator specifies that patients shown to have a progression risk of less than 5% should be monitored, those with a risk of 5% to 15% should be considered for treatment, and those with a risk greater than 15% should be recommended for treatment.
Those with moderate risk fall into a “gray zone,” Dr. Weinreb said, and the decision to treat them or not depends on many factors, including overall health status, life expectancy, commitment to treatment, and the adverse events and costs associated with treatment.
“This calculator should be an adjunct to, and not a substitute for, the expertise and judgment of the physician,” he said. “It is a tool and not meant to replace judgment.”
Dr. Weinreb added that the risk assessment tool presents an opportunity to track patients over time to see if the predictions are accurate and to “get a better assessment of the benefit of lowering IOP.”
“This is not an initiative to go out and put everyone on treatment,” he said. “It’s an initiative to more responsibly treat those who are most in need.”
Dr. Weinreb noted that this slide-rule-like version of the risk calculator will at some point likely be replaced by a computerized version, but he said this version was intended to be as simple as possible to facilitate widespread acceptance.