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Effects of Perceptual-motor Training on Collision Judgments with Peripheral Prism Expanded Vision
Kevin Edward Houston, Eli Peli1, Gang Luo1
1Massachusetts Eye and Ear Infirmary, Boston, Massachusetts.
Summary
Peripheral prisms (p-prisms) improve hazard detection in hemianopia but do not enhance collision judgment accuracy during simulated walking. Perceptual-motor training did not improve performance, indicating head and eye turning remains crucial for safety.
Area of Science:
- Ophthalmology and Vision Science
- Neuroscience
- Rehabilitation Medicine
Background:
- Peripheral prisms (p-prisms) aid individuals with hemianopia by redirecting visual information into their intact visual field, potentially improving hazard detection.
- While p-prisms enhance detection, the speed of collision judgment using only the prism-shifted image is slower than normal peripheral vision.
Purpose of the Study:
- To evaluate if perceptual-motor training, which improved pointing accuracy, could generalize to enhance collision judgments in individuals with hemianopia during simulated walking.
Main Methods:
- 13 participants with hemianopia performed virtual reality collision judgment tasks under fixed and free gaze conditions, with and without p-prisms.
- Measurements were taken immediately after fitting, after 2-week acclimation, post-training, and at 3-month follow-up.
- 13 controls completed a single visit without p-prisms for comparison.
Main Results:
- P-prisms significantly improved blind-side hazard detection from 40-82% to 97-99% (P < .001).
- However, collision judgments made solely through p-prisms were inaccurate and showed no significant improvement with perceptual-motor training or prolonged use.
- Initial use of p-prisms resulted in biased collision judgments towards the prism side.
Conclusions:
- Peripheral prisms effectively improve hazard detection in hemianopia but do not enhance the accuracy of collision judgments when relied upon solely.
- Perceptual-motor training did not yield improvements in collision judgment accuracy, suggesting it does not generalize from pointing tasks.
- Current recommendations for patients to turn their head and eyes to fixate hazards remain essential for safety.
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