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R. V. Jivrajka, D. Younessi, W. Fink, A. A. Sadun, J. Sebag; Quantitative Analysis of Central Visual Field Defects Using 3D Threshold Amsler Grid Testing in Patients With Macular Edema. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5522.
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© ARVO (1962-2015); The Authors (2016-present)
To examine the influence of contrast sensitivity on central visual field defects in patients with macular edema using 3D Computer Automated Threshold Amsler Grid testing.
Amsler grid abnormalities were measured in 17 eyes with focal macular edema and visual acuity > 20/80. Seated 12 inches from a touch screen computer monitor displaying an Amsler grid at a minimum contrast level (5% of standard Amsler grid), subjects outlined the visual field defect on the touch screen. This procedure was repeated 4 times with increasing levels of contrast, ultimately attaining 100% contrast levels comparable to a standard Amsler grid.
There were 3 eyes with no Amsler grid abnormalities at maximum contrast, but definite abnormalities at lower contrast levels. An inverse linear relationship existed between the amount of Amsler grid abnormality and the contrast level. At 100% contrast levels, the mean surface area of Amsler grid abnormality was 49.8 + 63 SA2 (arbitrary units). At 5% contrast levels, the mean surface area of abnormality was 214.6 + 164 SA2. The difference between the surface areas of Amsler grid abnormalities at the maximum and minimum contrast levels was found to be highly significant (p=0.000174, paired t-test).
Amsler grid abnormalities in macular edema can be quanitified through the addition of contrast sensitivity measurement using a customized computer program. The inclusion of contrast sensitivity in Amsler grid testing improves the ability to detect central visual field abnormalities due to macular edema. The results showed a four-fold greater abnormality at minimum contrast levels, as compared to 100% contrast. This approach to quantitative analysis of central visual field abnormalities may enable earlier disease detection as well as provide a quantitative outcome measure of therapeutic intervention efficacy.
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