TV for the Visually Impaired

Jan. 28, 2008 — -- Enjoying a favorite TV show can be difficult for someone with macular degeneration. Like many kinds of visual impairment, macular degeneration makes the images on the screen seem blurred and distorted. The finer details are often lost. Now researchers at the Schepens Eye Research Institute have developed software that lets users manipulate the contrast to create specially enhanced images for those with macular degeneration.

"Our approach was to implement an image-processing algorithm to the receiving television's decoder," says Eli Peli, a professor of ophthalmology at Harvard Medical School and the project leader. "The algorithm makes it possible to increase the contrast of specific size details."

The researchers focused their work on patients with age-related macular degeneration, a disease in which the macula--the part of the eye that's responsible for sharp, central vision--is damaged. According to the American Macular Degeneration Foundation, more than 10 million Americans suffer from the disease, which often leaves those afflicted with a central blind spot. A patient's remaining vision is often blurred, making it extremely difficult for people to watch television or even read the paper, says Mark O'Donoghue, clinic director of the New England College of Optometry's Commonwealth Avenue Clinic. "This is really new and fascinating to read about," says O'Donoghue. "I recognize the basic facts in the technology and the path of physiology in which [Peli] is doing this, and it is innovative."

Peli and his group currently have the new software running on a computer in their lab, but they're expecting to receive a prototype system built by Analog Devices in April 2008.

Peli's group discovered that patients suffering from macular degeneration could not perceive high-frequency waves in the visible spectrum, which left them unable to see fine details.

In order to give the patient a much better chance of discerning the image, the researchers designed an algorithm that specifically increases the contrast over the range of spatial frequencies that the visually impaired could see: the middle and low frequency waves. Ultimately, Peli says, the system enhances the contrast of the picture, and the result is that the finer details are more evident.