Eyeworld

EW SECONDARY FEATURE 71 3D computerized test distinguishes wet from dry AMD F or age-related macular de- generation (AMD) patients, a new test dubbed 3D- CTAG can help to differen- tiate wet from dry cases, according to J. Sebag, M.D., found- ing director, VMR Institute, Hunt- ington Beach, and professor of clinical ophthalmology, University of Southern California, Los Angeles. Results published in the January issue of the British Journal of Ophthal- mology indicated that 3D-CTAG picked up 100% of wet cases missed by traditional Amsler grid testing and 20% more dry cases. Dr. Sebag described the concept of the 3D-CTAG test, first developed by Alfredo A. Sadun, M.D., Doheny Eye Institute, University of Southern California, as a self-administered one. "Traditional Amsler grid is a test that is performed in the office, and we ask patients to do that test at home to monitor for the transition from dry to wet AMD," Dr. Sebag said. "What we're doing with the 3D test is in addition to having an Amsler grid, we're changing the con- trast between the lines and the back- ground at five predetermined steps of contrast and repeating the Amsler grid at different contrast levels." Computerization of the process was the work of Wolfgang Fink, Ph.D., CalTech, Pasadena, Calif. in con- junction with Dr. Sadun. Distinguishing types of AMD The hypothesis for this particular study was that by using 3D-CTAG testing on AMD patients, investiga- tors might be able to distinguish be- tween dry and wet cases. "It may lend itself well to a screening or at least a home self-monitoring test for the onset of wet AMD," Dr. Sebag said. This test is done on a computer touch screen with an Amsler grid shown, and patients are asked to trace any area of abnormality. The same screen is shown five times at different contrast levels and the pa- tient is asked to do this again. "That's assembled into a 3D plot, where the X and Y axes represent the Amsler grid and the Z axis repre- sents contrast," Dr. Sebag said. "The different levels are stacked and a 3D plot of the abnormality at all five contrast levels is presented." Dr. Sebag sees the approach as an interesting one for several rea- sons. "Not only will it provide a greater sensitivity to detect abnor- malities, but it also gives us a quanti- tative measure of central visual func- tion that should have more informa- tion in it than what we presently have available," he said. February 2011 October 2011 RETINA by Maxine Lipner Senior EyeWorld Contributing Editor Adding a new dimension to AMD testing continued on page 72 68-75 Feature 2 AMD_EW October 2011-DL2_Layout 1 9/29/11 3:48 PM Page 71

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