Computer display on glasses helps to overcome tunnel vision
11 September 2006
Scientists at Schepens Eye Research Institute, an affiliate of Harvard
Medical School, say a visual aid they invented promises to improve the
visual abilities of people with tunnel vision. In the first study to
evaluate this small high tech device, the research team saw a significant
increase in the effectiveness and speed with which visually impaired
individuals found objects.
The study — in the September issue of
Investigative Ophthalmology & Visual Science — shows that this device,
which combines a tiny camera, pocket-sized computer and transparent computer
display on a pair of glasses, may offer the most effective assistance to
date for this patient population.
“We are very pleased with the results of this first evaluation and hope
that with further study and refinement, we may soon make this device
available for the public,” says low vision expert Dr. Eli Peli, the
inventor, a senior scientist at Schepens, and a professor of ophthalmology
at Harvard Medical School and the senior author of the study.
About one in 200 Americans over age 55 suffers from tunnel vision, as a
result of diseases such as retinitis pigmentosa (RP) and glaucoma. RP can
begin to affect vision in one’s teen years and may become quite severe
tunnel vision by middle age. Residual tunnel vision occurs when peripheral
or side vision is destroyed, leaving only a small window of central vision.
The field of view of these patients can be likened to looking through the
tube of a roll of paper towels. Thus, tunnel vision can often cause the
individual to bump into or trip over obstacles. “Navigating city streets or
buildings can be quite challenging,” says Dr. Gang Luo, the study’s first
author, adding that for a person with tunnel vision, finding a misplaced
item is like searching for a key in a dark room using a tiny flashlight. Luo
is a research associate at Schepens Eye Research Institute and an instructor
in Ophthalmology at Harvard Medical School.
Until now, patients primarily have relied on long canes to warn them of
obstacles just in front of them. Glasses that act as reverse binoculars,
miniaturizing and pulling in the missing parts of their visual field, were
suggested and tried in the past. “The minifying glasses make things so small
that detailed visual information is sacrificed, so most patients have given
up these spectacles, and the most used type was discontinued last year” says
Peli’s new visual aid — which he developed with the help of MicroOptical
Corp. of Westwood, MA — allows the patients to see detailed visual
information through the transparent display, while also viewing a
superimposed minified outline version of a wider visual field. The tiny
computer-video system provides updated outline information 30 times per
second. When a patient becomes aware of a possible obstacle or important
object in the superimposed outline image, he can move his head and eyes to
look directly at the object through the display.
“All patients only had an hour of training on this device before they
were tested,” says Luo “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
Based on these results, and following further improvement of the device,
the team will test the usefulness of the device by providing it to patients
for use in their homes and for outdoor activities.