Central focus visual field test measures glaucoma defect change with precision
BOSTON – The 10-2 visual field test provided a greater dynamic range for measuring potential visual field defect change in glaucoma compared with the 24-2 test, according to a study presented at the American Academy of Optometry annual meeting.
“When we consider the current way that we’re measuring the visual field in eye diseases like glaucoma, it’s primarily related to the general overview of your vision, including peripheral vision,” Jack Phu, BOptom (Hons), BSc, MPH, PhD, FAAO, from the University of New South Wales, said during a virtual academy-sponsored press conference. “Our research question was when would it be useful to start assessing the central 10 degrees of visual field, because we can agree that’s also very important.”
Phu and his colleague from the University of New South Wales, Michael Kalloniatis, PhD, took the current clinical standard 24-2 test, a 10-degree focused test of the visual field, and chose vertical and horizontal meridians that were approximately overlapping between the two test grids.
They then calculated the number of discrete meaningful steps in increments of 3 dB to the visual field measurement floor of –22 dB.
Phu and Kalloniatis examined the 10-2 and 24-2 test results of 73 patients with central visual field defects.
The magnitude of the deepest defect across all meridians as well as the difference in defect were similar between grids. Phu said that this meant the 24-2 had a “flatter gradient” of dB per degree, as it has 6-degree point spacing, compared with the 2-degree point spacing of the 10-2 test (range from P = .02 to P < .0001).
“What this flat gradient implies is that there is missing information between the test locations that are assessed on the 24-2 because of the resolution of the test, as it’s not so focused on the central visual field.
Phu and Kalloniatis also found that there were proportionally fewer instances where the measurement floor was reached (P < .0001) and a greater number of steps remaining (P = .01) with the 10-2 test compared with the 24-2 test.
“We concluded that the 10-2 test with a 10 degree focus provides more opportunities for characterizing and monitoring central visual field defects in comparison to the clinical standard, so we recommend it for use even in the early stages of glaucoma,” Phu said.
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Phu J, Kalloniatis M. The 10-2 provides more information for tracking visual field progression in central visual field defects compared to the 24-2. Presented at: American Academy of Optometry annual meeting; Nov. 2-6,2021; Boston.