HELPING THE ALMOST-BLIND SEE BETTER
In a state-of-the-art ophthalmology laboratory at the University of Illinois at Chicago, patients losing their vision due to degenerative eye diseases can be trained to see better, relying on islands of the retina that are still functioning.
"A person may lose critical areas of the retina that are used to discriminate detail or detect objects in the visual landscape - areas that are necessary for activities like reading or driving," said Dr. Janet Szlyk, director of UIC's Low Vision Laboratory. "We have developed scientifically based strategies whereby visually impaired patients can maximize their remaining vision for these kinds of tasks to improve their quality of life."
Rehabilitation begins by mapping the visual acuity of 27 discrete locations on the retina where functioning cells may be found mixed in among diseased areas. Relying on technology developed at UIC, the system, called functional microperimetry, takes precise measurements of the visual acuity at each location in real time. The device for the measurements, attached to an ophthalmologist's traditional slit lamp, presents letters to the patient at different focal points on the retina. The data are recorded electronically, producing a three-dimensional chart of each location's ability to resolve images.
These data are supplemented with an analysis of the potential longevity of the retinal cells. The analysis is done using a commercially available device called a multifocal electroretinogram, which assesses the relative electrophysiological strength of 103 areas across the retina. Using a contact lens electrode placed on the patient's eye, the device measures the electrical current at each site on the retina as the patient stares at a checkerboard pattern flashed on a test monitor.
Combining data from both sets of noninvasive tests, UIC researchers can identify those areas of the retina that not only are still capable of responding to light but are likely to survive the ravages of the degenerative disease longer. Visual rehabilitation focuses on training the individual to use those regions as surrogate fixation areas in tasks like reading and driving.
Rehabilitation is likely to help people suffering from a range of degenerative eye diseases, including age-related macular degeneration, which destroys the central portion of vision, diabetic retinopathy, a complication of diabetes mellitus, and glaucoma, a set of diseases that leads to atrophy of the optic nerve and partial or total vision loss.
Age-related macular degeneration affects about 30 percent of the Caucasian population aged 75 or older, and lower percentages of the African-American and Hispanic populations. An estimated 700,000 Americans have diabetic retinopathy; 65,000 new cases are reported annually. The incidence of glaucoma is roughly 2.1 percent in Caucasians and three or four times that in African-Americans.
UIC's Low Vision Laboratory includes a driving simulator with an eight-minute test course and accompanying software developed by UIC researchers to assess the driving risks of visually impaired individuals. The software analyzes 15 driving-performance variables and compares scores against the performance of individuals with normal vision, matched for age and sex. The variables are incorporated into a mathematical model that computes the likelihood of the individual's having an automobile accident.
Szlyk and her colleagues have developed rehabilitation plans for patients based on their performance on specific simulator measures. Rehabilitation programs for reading and other tasks are expected to begin soon.
The UIC department of ophthalmology is ranked among the top 18 in the country, according to U.S. News & World Report.
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