Evaluation of Phosphene Shifts During Eye Movements to Enhance Safe Visual Assistance for Visually Impaired Individuals

Hands-free visual assistive devices that consider the safety of the visually impaired have been researched, but many of them interfere with other senses, such as hearing. Therefore, phosphenes have been researched as a method of presenting visual information. Phosphenes are flashes that are recognized by electrical stimulation, and the presentation position can be adjusted by the electrode arrangement. However, it has been reported that the presentation position changes significantly when the eyeballs are moved as far left and right as possible. As a walking assistive device for the visually impaired, the fluctuation of the presentation position of phosphenes may cause safety problems. This study used the Hess test to verify the positional fluctuation of phosphenes associated with eye movement and compared it with eye movement during walking to discuss safety. As a result, the range of the change in the presentation position of phosphenes was significantly large when subjects moved their eyes to the peripheral vision, the same as in the previous study. On the other hand, the presentation position of phosphenes did not change significantly within the range of eye movement during walking (±15 deg). Our results suggest that there is the possibility that serious safety issues will not happen with assistive devices for the visually impaired who use phosphenes.