The StrokeVR project explores the ability to detect visual stimuli in patients with damage to the brain's primary visual cortex. A controlled VR environment has been created to allow measurement of response times when objects appear in a participant's peripheral vision.
Vision, as the dominant sense in humans, is critically important to our navigation in the world and for social interactions with others. Although the eyes are the sensory organ for detecting light, the majority of visual processing is performed in the brain. Specifically, the primary visual cortex (V1) is the first area of the cerebral cortex to receive visual information. If this area is damaged on one side, then patients are unable to see the opposite side of the world, a condition known as hemianopia. However, even when people have damage to V1, they often retain some ability to detect visual stimuli, both with and without awareness, termed "blindsight". Extensive investigation of this phenomenon has demonstrated that people with blindsight can detect many different types of stimuli, but greatest sensitivity is to motion. Patients with hemianopia undertaking rehabilitation over a period of months have shown a reduction in the blind region of their visual fields, suggesting an improvement in vision.
One of the drawbacks of the current approach is that the quantification of improvement, like the training, uses computer-based testing or mapping of visual fields using spots of light. Neither of these approaches can easily be quantified to determine whether they improve the ability of participants to see more of the world and objects around them. Specifically, the approaches
In addition to a training programme that participants will undertake at home, changes in the brain can be quantified using magnetic resonance imaging, before and after training. Visual field measurements, vision-related quality of life questionnaires and computer-based visual tests will be used to quantify behavioural improvements in vision related to the training.
We have built a VR environment in which participants will be required to locate moving objects presented within the blind region of the field e.g. abstract shapes, cars, lorries, cyclists. The speed of the objects and frequency can be varied as part of the test and patients are then assessed on how quickly they see the object in their peripheral vision. Eye-tracking within the VR headset will allow us to know whether the patient directly looks at the objects which would invalidate the test - if they have the test can be reset or the object can be moved away from the gaze within the VR environment to compensate.