Field Expansion Prism Glasses for Homonymous Hemianopsia

Period of Performance: 05/01/2006 - 04/30/2007


Phase 2 SBIR

Recipient Firm

Chadwick Optical, Inc.
White River Junction, VT 05001
Principal Investigator

Research Topics


DESCRIPTION (provided by applicant): The broad, long term objective of this application is to overcome optical design, ergonomic and cosmetic obstacles standing in the way of innovative ophthalmic lens designs for low vision enhancement, particularly field expansion for Homonymous Hemianopsia. Phase I resulted in the manufacture of the EP-Horizontal expanding the visual field of hemianopes by 20 degrees into the unseeing area. One approach in Phase II is to increase expansion modestly with the use of higher power prisms and move field into midline view. A second approach introduces a more complex device that could expand the visual field by more than 40 degrees using prisms in excess of 80 diopters, also arranging them to shift images to midline, the area important for general mobility and driving. These prism components will be incorporated into a pair of eyeglasses, effectively doubling the expansion of the current design. Arranged properly, this configuration would safely allow victims of stroke, brain trauma and tumor (many young and otherwise healthy) to enjoy a vast increase in mobility, occupational choices, and potentially regain their ability to drive without endangering themselves or others. These devices will be evaluated in Multi-center clinical trials and driving simulator studies using various prism powers, angles and components. These evaluations will determine the optimal configuration of the final design. One component to be tested is the ComPrism designed to reduce the chromatic aberration inherent in high power prisms. Fitting and prescribing protocols will be established. Although the actual number of Hemianopes and Quadranopes is unknown, extrapolating data of stroke and head trauma cases indicate the number to be over a million per year in the U.S. alone. Hemianopes are totally unseeing in half their visual field. One year after the incident, only half this population has returned to work. The condition causes victims to run into obstacles on the blind side and they are afraid of being in crowded places. Significant Phase 2 improvements can be made to our current, Phase I, EP-Horizontal design to allow people with field loss to regain their place in the workforce and society.