OCT guidance may help improve detection of visual field worsening
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Measuring a specific area of visual field over time with OCT guidance improved detection of visual field worsening, particularly in less severe cases of glaucoma, according to a speaker.
“Our hypothesis here was that if we use a baseline OCT scan to inform the portion of the visual field to follow over time, we’d be able to better detect visual field change by focusing on structurally correlated functional damage and reducing the noise of testing,” Jithin Yohannan, MD, MPH, said at the American Glaucoma Society meeting.
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A study included 5,191 eyes of 3,133 patients split into two data sets. The internal Wilmer data set included patients with glaucoma and glaucoma suspect status who had seven 24-2 SITA standard visual field tests over time and one OCT scan within 1 year of the initial visual field test, while the external Halifax data set included one eye each of 30 patients with stable glaucoma who underwent 12 visual field tests in 3 months to ensure a more stable visual field with no change over time.
The researchers compared the standard method of detecting visual field loss, which measures linear regression of mean deviation of visual field slope change over time, with two OCT-guided methods. The first method used the Garway-Heath (GH) zone to select the visual field area with the most structural damage, defined as the lowest percentile retinal nerve fiber layer (RNFL) thickness value at baseline across the population. The second method followed the hemifield portion of the visual field slope, which contained the lowest RNFL thickness GH zone.
The OCT GH zone approach showed the best performance in detecting changes in visual field in the whole population, followed by the OCT GH hemifield approach and then the standard mean deviation approach. However, the standard method demonstrated the best detection of visual field worsening in cases with more severe glaucoma, Yohannan said.
“This is likely due to the floor effect on OCT, where OCT does not add much information about which visual field portion to follow when you have advanced change,” he said. “This can assist in helping us identify worsening more quickly and in doing more timely intervention, and it may be used in future clinical trials to optimize endpoints.”
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Yohannan J. Improving the detection of VF worsening by using OCT guidance. Presented at: American Glaucoma Society meeting; Feb. 29-March 3, 2024; Huntington Beach, California (hybrid meeting).
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