Mixed Reality Glasses with Picture-in-Picture Navigation for Patients with Homonymous Hemianopic Visual Field Loss.

Background: The visual rehabilitation options for patients with homonymous hemianopia (HH) are limited. We developed prototype software for commercially available mixed reality glasses (MRG) to help patients with HH better navigate their visual environment.

Methods: Unlike virtual reality, mixed reality allows users to see the actual environment with superimposed holograms. We developed software on the Unity platform for the Microsoft HoloLens 2 MRG to enable real-time picture-in-picture navigation (PIPN). With PIPN, a miniaturized view of the visual environment is transposed into the intact visual field in patients with HH. WebSockets was used for real-time communication between the MRG and remote interface. External calibration controls were developed with the Streamlit web-based interface. In this crossover study, patients with HH were tested on a timed obstacle course with and without the MRG and asked to rate the utility of PIPN on a linear analog scale.

Results: We transposed 52 diagonal degrees of the full field as a picture-in-picture into the intact hemifield of patients with HH. Five patients with HH were tested and on average rated the MRG as 19.7% more helpful for ambulation ( P = 0.028). On average, walk times with the MRG were 6 seconds slower than walk times without the MRG, but this was not statistically significant.

Conclusions: We developed working prototype software for PIPN on a commercially available MRG. PIPN is a viable rehabilitation option to improve ambulatory navigation for patients with HH and will continue improving with hardware and software advancements.