Creating a Virtual Environment to Simulate Hemianopsia: Eye Tracking-Based Analysis of Visual Exploration

The human visual system is one of the most complex and crucial components for interaction with the surrounding world. Light enters the eye and is converted into electrical signals by the retina, which then travel through the optic nerve to the brain. A critical point in this pathway is the optic chiasm, a structure located at the base of the brain where the optic nerves from each eye meet and partially cross. A typical consequence of lesions at the optic chiasm, as well as post-chiasmatic lesions, is hemianopsia, a condition that results in the loss of a portion of the visual field. There are different types of hemianopsia, each with specific functional implications. This condition can have significant consequences on the quality of life of patients, who may encounter difficulties in daily activities such as reading, driving, and navigating both familiar and unfamiliar environments. Rehabilitation and accurate diagnosis of these conditions represent a significant challenge for modern medicine. In this context, virtual reality (VR) emerges as a promising technology to create safe and controlled environments where new methods of assessment and treatment can be experimented with. This thesis focuses on the creation of a virtual reality environment using Unity software, with the aim of analyzing the differences in visual patterns between individuals with simulated hemianopsia and those without. A virtual domestic environment was created, representing a part of a house, where participants were asked to perform specific tasks involving interaction with objects and reading. Additionally, a commercial environment and a driving environment were also developed. Sixty participants, aged between 18 and 61, took part in the experiment, exploring each of the three environments. Using Unity, two visual defects typical of hemianopsia were simulated, by obscuring the left portion of the visual field in two variants. Each participant experienced at least one of the three environments without simulated defects and at least one of the two defects in the other environments. The experiment was conducted in the 3D Lab of the Politecnico di Torino. Participants were briefed on the experimental protocol and informed consents were collected. During the experience, an EMOTIV Epoc EEG headset with 32 electrodes was used to acquire brain signals, a Shimmer3 GSR+ device to measure skin conductance and heart rate, and an Oculus Meta Quest Pro headset with eye-tracking functionality. At the end of the experience, participants completed a questionnaire with questions related to their experiences in the virtual environments. Although analyses were conducted on various physiological parameters, this work primarily analyzes data extracted through eye tracking, focusing on the differences in visual scanning patterns and the number and duration of fixations on objects observed between participants with and without simulated visual defects. An analysis of the area of the environment explored and the playtimes was also conducted. The results highlighted significant differences in visual scanning patterns, with particular variations in the times and areas of space exploration.