Study Confirms Effectiveness of Innovative Prism Glasses For Hemianopia Patients

Suggests additional training to help brain adapt more fully and further
enhance benefits

BOSTON, May 19 /PRNewswire-USNewswire/ -- In a study of specially designed
peripheral prism glasses for hemianopia patients (blinded in half the visual
field in both eyes), scientists found that two-thirds of patients continued to
wear the glasses at the end of the study period and beyond, indicating a high
level of success. They also found that the brains of patients had not fully
remapped to adjust for the prisms, which means that improved training in their
use could further enhance the benefits, says principal investigator, Dr. Eli
Peli, a senior scientist at Schepens Eye Research Institute and inventor of
the glasses.

The study, published in the May 2009 issue of Optometry and Vision Science,
not only reaffirms previous clinical studies, but also adds a deeper
understanding of the neurological processes at play when a patient uses prisms
for this purpose, adds Peli.

More than a million Americans suffer from hemianopia, which blinds the vision
in one half of the visual field in both eyes -- the result of strokes, tumors
or trauma. Hemianopia patients are often unaware of what they cannot see and
frequently bump into walls, trip over objects or walk into people on the side
where the visual field is missing.

The prisms, attached above and below the center of a spectacle lens in Peli's
invention, shift images from one side of the visual field to the other side
and alert patients to objects and obstacles not otherwise visible to them.
Alerted to the existence of these objects, patients turn to look, or, if their
brains are fully adapted (remapped), perceive quickly where the objects are
and automatically avoid them without turning their eyes and head. (In earlier
designs by other scientists, the prism was in the middle of the lens and
caused double vision.)

"The best case scenario," says Peli, "is for a patient to be able to make
rapid decisions based on the perception rather than moving their heads when an
unseen object is detected."

Peli and his team asked 28 patients with complete hemianopia to wear the
peripheral prism glasses as much as possible for the duration of the study,
which averaged about nine weeks. Success was measured by continued wear,
visual field expansion, perceived direction (caused by brain remapping), and
perceived improvement in quality of life.

The research team found that 67 percent of patients chose to continue to wear
the glasses at the end of the study. They also found that all patients had
expansion of their visual field of about 22 degrees and expressed reduced
difficulty in noticing and avoiding obstacles. On the other hand, only two
patients demonstrated even an intermittent adaptation to the change in visual
direction produced by the peripheral prism glasses, which means that no
patient had remapped his or her brain to automatically make the perceptual
adjustment.

Based on these results, Dr. Peli and his team plan to conduct future research
that will examine the best way to train patients to reprogram their brains to
perceive direction automatically.

The research team consisted of Mr. Robert Giorgi and Drs. Russell Woods and
Eli Peli, all of the Schepens Eye Research Institute.

This study was conducted with a prototype of the glasses, on which the prisms
are temporarily applied. There are now permanent prism glasses available,
which continue to be studied and perfected in on-going multi-center trials.

Patients interested in trying the peripheral prism glasses can contact
Chadwick Optical for referral to a doctor in their area. Go to
http://www.chadwickoptical.com/ for contact information.

Schepens Eye Research Institute is an affiliate of Harvard Medical School and
the largest independent eye research institute in the nation.

SOURCE Schepens Eye Research Institute

Patti Jacobs of the Schepens Eye Research Institute, +1-617-864-2712,
pjacobs12@comcast.net