Study Confirms Effectiveness of Innovative Prism Glasses For Hemianopi...( Suggests additional training to help ...),Health

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.)

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