Assessing visual detection ability for mobility in individuals with low vision

Abstract

We investigated the mobility performance of legally blind patients with age-related maculopathy (ARM) as assessed by their ability to visually detect hazards in their travel path. The three types of hazards were: drop-offs (a curb), obstacle on the travel surface (a small wastebasket), and a head-height obstacle (a piece of foam insulation projecting across the travel path at head height). We also recorded the patient’s logMAR visual acuity and Pelli-Robson contrast sensitivity. Three distinct daylight assessments were made in a naturalistic outdoor environment: an initial assessment of distance to visually detect each of the three types of hazards; an assessment designed to assess the subject’s maximum potential visual detection distance; and a final assessment following training and fitting with filters to reduce glare to determine the increase, if any, in visual detection distance for the three types of hazards. The inter-rater and test/retest reliabilities of the assessment procedure were studied. The...