Assessing Patients with Central Field Loss Using a Low-Cost Virtual Reality System with Head Tracking

摘要

Central visual field loss is a common and debilitating problem, especially among the elderly. These individuals experience significant difficulties in performing daily tasks, and navigating streets is both challenging and potentially hazardous. The recent development of low-cost virtual reality (VR) technologies provides a potential assessment and training platform that emulates many aspects of daily life, without the associated risks. We introduce a novel testing environment with both monocular and binocular cues to depth, using a custom handheld VR simulation on an Android smartphone. Five CFL patients and 1 age-matched control were included in the study. Participants were asked to wear a VR headset. Each session consisted of two parts. First, acuity was tested in the VR device, using single letters whose size was controlled by a 2 up-1 down staircase, until threshold was reached. The threshold letter size was used for the rest of the experiment. In the second part, patients were presented with a looming wagon-wheel stimulus in fovea-centered coordinates. Observers reported the number of spokes (3, 5, or 7 randomly assigned) when the wagon wheel came into view and then identified a letter in the center, while interacting with the device via provided levers. Head movements could be resolved to a fraction of a degree, and were clearly evident in switching between the centering task (wagon wheel) and fixational task (letter identification) for the participant with a very eccentric fixation locus. All participants found the tasks compelling and engaging, reporting no motion sickness or other discomfort.