Video-linked glasses may ease effects of tunnel vision

A new device that projects a visual display on a pair of eyeglasses may help improve the visual abilities of patients with tunnel vision, a study found.

Eli Peli, MD, and colleagues at Harvard Medical School and the Schepens Eye Research Institute developed the device, which consists of a small camera attached to a pair of eyeglasses. The camera captures a wide visual field and renders the images as contour-only overlays that can be seen in the restricted field of view of the patient with tunnel vision. The overlays, which look like detailed chalk outlines, are superimposed over the patient's normal, more detailed vision, and refreshed 30 times per second. This allows wearers to perceive shapes and figures beyond their narrow visual field, according to the study.

Dr. Peli and colleagues evaluated the device's efficacy in 12 patients with tunnel vision. These patients searched for targets outside their field of view on small and large black backgrounds.

Using the modified eyeglasses, patients' search paths showed greatly improved directness for both background areas. Patients who searched a large area had a 28% to 74% reduction in search time, and patients with visual fields wider than 10° who searched a smaller area showed a 22% reduction in search time, according to the study.

"All patients only had an hour of training on this device before they were tested," said Gang Luo, PhD, first author of the study. "The search directness was improved for all subjects, which means they were not searching aimlessly, as they did without the device. However, the speed of head and eye movements was reduced when patients used the yet unfamiliar device. We believe that a few days of training would improve their speed and thus increase their search abilities dramatically."

The study is published in the September issue of Investigative Ophthalmology & Visual Science.

To see a video of the device in use, click here.