What areas of of the visual field are important for mobility in low vision patients

Abstract

1. The relationship between binocular visual field size and orientation and mobility performance was examined for nine low vision patients and nine age-matched normals.
2. Mobility performance was determined by measuring time taken and number of errors made by subjects on an indoor course.
3. Mobility performance is significantly influenced by the total visual field extent, such that the smaller the solid angle subtended by the total field at the eye, the poorer is the mobility performance.
4. The relationship between visual field and mobility performance varies across the binocular field. The central 37 deg radius zone and right, left and inferior mid-peripheral areas appear to be the most important for mobility.
5. The time taken to traverse the course and the number of errors made are both good predictors of mobility performance, although number of errors correlates more highly with visual field extent.
6. Horizontal objects at head height and large objects on, or suspended just above, the floor are those most likely to present difficulties to low vision patients.