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New visual function test for glaucoma on the horizon
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TAMPA, Fla. – A recently developed device that uses pupillary light reflex (PLR) to measure the presence of glaucoma was presented here at the American Academy of Optometry meeting.
The device, which has not yet been named, was invented by Harry J. Wyatt, PhD, FAAO, of the State University of New York. Dr. Wyatt believes measuring PLR may soon help clinicians monitor progression of the disease, if not diagnose it outright. The test, he asserts, takes only 18 seconds per eye and is patient friendly.
“When it comes to functional testing, the standard has been looking at the visual field,” Dr. Wyatt told Primary Care Optometry News in an interview. “The problem with visual field testing is that it’s a very demanding test. Many patients with glaucoma who have to do it regularly don’t like it.”
Dr. Wyatt and his colleagues worked several years to develop a test that would be faster and easier on patients. They determined they could take PLR measurements when flashing shaped stimuli to capture the likely territories of damage from glaucoma.
“We analyze the pupil for 18 seconds while measuring the sensitivity to the stimuli,” Dr. Wyatt said, adding that a paper on the test is scheduled to be published soon in the journal Optometry and Vision Science.
According to the poster, which was co-authored by Heather McCleod, OD; Richard J. Madonna, OD, MA, FAAO; Mitchell W. Dul, OD, MS, FAAO; and William H. Swanson, PhD, FAAO, the PLR measurements taken were compared to clinical measurements of retinal nerve fiber layer (RNFL) thickness in glaucoma patients. The RNFL was measured with Heidelberg Engineering’s retinal tomography device HRT3.
“Nonparametric statistics were used to compare the PRL and RNFL measures in terms of the logarithm of the ratio of the superior and inferior measures for each stimulus,” according to the poster. “PLR and RNFL data were obtained from 76 eyes of 43 patients diagnosed with primary open angle glaucoma.”
Correlations were strongest for patients with mid-range defects (-5 dB > MD > -10 dB) for which r = 0.507, Dr. Wyatt said. “It seemed to do well overall,” Dr. Wyatt added.
Dr. Wyatt couldn’t divulge much information about the new device, but said it would probably be marketed early next year. “It’s imminent,” he said.