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William H. Swanson, Mitchell W. Dul, Douglas G. Horner, Tiffany Liu, Irene Tran; Assessing Spatial and Temporal Properties of Perimetric Stimuli for Resistance to Clinical Variations in Retinal Illumination. Invest. Ophthalmol. Vis. Sci. 2014;55(1):353-359. doi: 10.1167/iovs.13-11640.
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© ARVO (1962-2015); The Authors (2016-present)
To develop perimetric stimuli for which sensitivities are more resistant to reduced retinal illumination than current clinical perimeters.
Fifty-four people free of eye disease were dilated and tested monocularly. For each test, retinal illumination was attenuated with neutral density (ND) filters, and a standard adaptation model was fit to derive mean and SEM for the adaptation parameter (NDhalf ). For different stimuli, t-tests on NDhalf were used to assess significance of differences in consistency with Weber's law. Three experiments used custom Gaussian-windowed contrast sensitivity perimetry (CSP). Experiment 1 used CSP-1, with a Gaussian temporal pulse, a spatial frequency of 0.375 cyc/deg (cpd), and SD of 1.5°. Experiment 1 also used the Humphrey Matrix perimeter, with the N-30 test using 0.25 cpd and 25 Hz flicker. Experiment 2 used a rectangular temporal pulse, SDs of 0.25° and 0.5°, and spatial frequencies of 0.0 and 1.0 cpd. Experiment 3 used CSP-2, with 5-Hz flicker, SDs from 0.5° to 1.8°, and spatial frequencies from 0.14 to 0.50 cpd.
In Experiment 1, CSP-1 was more consistent with Weber's law (NDhalf ± SEM = 1.86 ± 0.08 log unit) than N-30 (NDhalf = 1.03 ± 0.03 log unit; t > 9, P < 0.0001). All stimuli used in Experiments 2 and 3 had comparable consistency with Weber's law (NDhalf = 1.49–1.69 log unit; t < 2).
Perimetric sensitivities were consistent with Weber's law when higher temporal frequencies were avoided.
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