# Head and Eye Movements During Pedestrian Crossing in Patients with Visual Impairment: A Virtual Reality Eye Tracking Study

## TL;DR

This study uses virtual reality to show how different types of visual impairment affect how people cross roads, finding that head and eye movement patterns vary significantly and suggest new ways to assess and help visually impaired individuals.

## Contribution

The study introduces a VR-based method to assess functional navigation in visual impairment, revealing distinct head-eye movement profiles that better explain behavior than traditional WHO classifications.

## Key findings

- Patients with combined visual impairment performed worse in detecting safe crossing intervals and had fewer microsaccades and head turns.
- Head-eye movement patterns differed by impairment type, with central impairment showing shorter saccades and peripheral impairment showing exploratory behavior similar to controls.
- Functional impairment classification explained behavior better than WHO-based categorization.

## Abstract

Real-world navigation depends on coordinated head–eye behaviour that standard tests of visual function miss. We investigated how visual impairment affects traffic navigation, whether behaviour differs by visual impairment type, and whether this functional grouping better explains performance than WHO categorisation. Using a virtual reality (VR) headset with integrated head and eye tracking, we evaluated detection of moving cars and safe road-crossing opportunities in 40 patients with central, peripheral, or combined visual impairment and 19 controls. Only two patients with a combination of very low visual acuity and severely constricted visual fields failed both visual tasks. Overall, patients identified safe-crossing intervals 1.3–1.5 s later than controls (p ≤ 0.01). Head-eye movement profiles diverged by visual impairment: patients with central impairment showed shorter, more frequent saccades (p < 0.05); patients with peripheral impairment showed exploratory behaviour similar to controls; while patients with combined impairment executed fewer microsaccades (p < 0.05), reduced total macrosaccade amplitude (p < 0.05), and fewer head turns (p < 0.05). Classification by impairment type explained behaviour better than WHO categorisation. These findings challenge acuity/field-based classifications and support integrating functional metrics into risk stratification and targeted rehabilitation, with VR providing a safe, scalable assessment tool.