University of Iowa News Release
Dec. 03, 2003
UI Researchers Receive Grant To Improve Vision Tests For Glaucoma
A team of researchers from University of Iowa Health Care and the Iowa City Veterans Affairs Medical Center (VAMC) is conducting a study to identify the most effective method for determining whether a patient's vision has changed. Detecting changes in vision is the basis for treatment decisions in many visual disorders including glaucoma, which affects approximately three million Americans and is a leading cause of blindness in the United States. The study is funded by a five-year, $720,000 Veteran Affairs Merit Review grant.
Automated testing of peripheral vision is commonly used to determine vision changes and hence determine treatment options for patients with glaucoma. However, although the automated testing is sensitive, results of this standard test can be highly variable so as many as six to eight separate tests may be needed to confirm that change is occurring in a patient's vision.
"Treatment decisions are based on whether vision is getting better or getting worse, so variability in the testing method becomes a serious problem as it complicates the determination of change," explained Michael Wall, M.D., (left) professor of neurology and ophthalmology and visual sciences in the UI Roy J. and Lucille A. Carver College of Medicine, and principal investigator of the study. "If we have to do multiple tests over many years in order to detect change, there is a delay in getting more aggressive with therapy."
The study will compare the variability of four vision tests: conventional automated perimetry with small stimuli; conventional automated perimetry with large stimuli; motion perimetry; and multi-focal visual evoked response test. Patients with glaucoma will receive all four tests every six months for four years.
Wall, a neuro-ophthalmologist at the UI and the VAMC, and his colleagues believe that part of the problem with the standard perimetry test is that the stimuli (the object that the patient "sees") is too small and that one way to improve variability of the vision test would be to increase the size of the stimuli.
"We have shown there is a much lower variability using the larger stimuli," Wall said. "We now want to know what happens over time -- the grant will help us assess these tests over time."
The researchers will test the variability of conventional automated perimetry using two sizes of stimuli - the standard small stimuli and larger stimuli.
The third test in the study, motion perimetry, which was developed at the UI, also appears to have low variability. In this test, the stimulus is movement.
"The primary function of the peripheral field is to detect movement and the motion perimetry test really asks the question: 'do you see something moving?'" Wall explained. "The test is designed so that the moving stimuli change size until the procedure finds the smallest area of motion the patient can detect. In areas of visual loss it takes a larger stimulus for the patient to see something and in areas of normal vision it takes a smaller stimulus."
The fourth test, the multi-focal visual evoked response, measures electrical brain activity of the peripheral visual field. The electrical activity recorded is proportional to the amount of vision that the patient has in that area of their visual field. This test also aims to lower test variability because it essentially minimizes the patient's active participation in the test.
"We are hoping to see differences among the four tests in terms of how efficiently and how early they can accurately detect change," Wall said.
The study will primarily focus on testing vision loss in glaucoma patients, but the researchers believe that the study results should help improve detection of any disease that causes changes in vision.
In addition to Wall, the UI study team includes Carrie Doyle, study coordinator, Kim Woodward, head research assistant, Jenne Allen, research assistant, Wallace Alward, M.D., professor of ophthalmology and visual sciences, Young Kwon, M.D., Ph.D., associate professor (clinical) of ophthalmology and visual sciences, Emily Greenlee, M.D., associate in ophthalmology, Benita Carney, research assistant, Randy Kardon, M.D., Ph.D., associate professor of ophthalmology and visual sciences, Andrew Lee, M.D., associate professor of ophthalmology and visual sciences, neurology and neurosurgery, and Susan Anderson, research assistant. Alward, and Kardon also are VAMC staff physicians.
University of Iowa Health Care describes the partnership between the UI Roy J. and Lucille A. Carver College of Medicine and UI Hospitals and Clinics and the patient care, medical education and research programs and services they provide. Visit UI Health Care online at www.uihealthcare.com.
STORY SOURCE: University of Iowa Health Science Relations, 5141 Westlawn, Iowa City, Iowa 52242-1178
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PHOTOS/GRAPHICS: Photos for this story are available for downloading at http://webeye.ophth.uiowa.edu/dept/BIOGRAPH/WALL.JPG