EYES GET FIVE: A five-minute computerized vision test helps ophthalmologists better diagnose visual disorders.
by Jill Perry
Ophthalmologist Alfredo A. Sadun, M.D., Ph.D., and Caltech physicist Wolfgang Fink, Ph.D., have developed a new five-minute vision test using a desktop computer and touch-sensitive screen. The test shows promise as a diagnostic tool for a variety of eye diseases and even certain brain tumors.
The 3-D Computer-Based Threshold Amsler Grid Test, invented by Sadun and Fink, offers a novel method for medical personnel to evaluate the central visual field. The test is sensitive and specific enough to allow an ophthalmologist to diagnose visual disorders such as macular degeneration, and to discriminate between visual disorders with subtly different symptoms, such as macular edema and optic neuritis.
In order to take the test, the patient sits in front of a touch-sensitive computer screen displaying a grid pattern and a central bright spot. Staring at the central spot with one eye closed, the patient uses a finger to trace around the portions of the grid that are visible, and the computer records the information.
After the computer records the patient's tracings, the operator changes the contrast of the grid slightly and the patient again traces the visible portions of the grid. This process is repeated with several contrasts and information is gathered for the computer to process a three-dimensional profile of the patient's visual field for that eye. Then, the process is repeated for the other eye.
Patients suffering from macular degeneration, for example, experience a loss of vision at the central focus and thus will have trouble seeing the grid pattern near the center. Since these patients have good peripheral vision, they would likely trace a central hole on the screen, and if they also had a relative field defect, they might trace an ever-smaller circle as the brightness of the grid pattern intensified. Once the information was processed, the 3-D graph would provide doctors with a complete description of what the patient sees under various conditions.
The test will be useful for many diseases and conditions such as macular degeneration, optic neuritis, detached retina, glaucoma, anterior ischemic optic neuropathy (AION), macular edema, central or branch retinal artery occlusions, and several genetic impairments. Also, the test can be used to detect, characterize, and even locate several types of brain tumors.
The new test is more revealing, quicker and simpler than existing methods of characterizing the visual field, says Sadun. Likening the test to a recreational video game, Sadun says, "The patient is playing the game while the machine is digesting the information." He says the new technology will be a powerful means of processing patient data and, hopefully, also inexpensive and easily marketable.
The test has been used since April 2000 on about 80 patients suffering from glaucoma, macular degeneration, AION and optic neuritis.
For more information about the 3-D Computer-Based Threshold Amsler Grid Test, or to learn more about The Doctors of USC, call 1-800-USC-CARE (1-800-872-2273).