Relation of walking behavior and visual function during the Graz Mobility Test

Abstract

Abstract Purpose Epiretinal prostheses are developed to enhance the orientation of low vision patients and consequently their mobility. However to document visual progress repeated testing is necessary to eliminate learning effects. For this purpose we developed the Graz Mobility Test (GMT) and evaluated its suitability in low vision patients with retinitis pigmentosa. Aim of this study was to investigate the relation of visual function parameters and walking behavior of patients. Methods Low vision patients (n=16) with visual acuity (VA) ranging from light perception to 1.0 logMAR passed through a mobility test consisting of four different, structurally similar mazes with black obstacles. Each test was completed four to six times. A people tracking system and a specially designed computer program recorded head movements and the patient´s walking path. In addition passage time and number of contacts were recorded. VA was tested with the Modified Grating Test (MGT) and visual field (VF) was examined with the Goldmann perimeter. Results The subjects were divided into groups according to their VA. Patients with eccentric fields in general proved to have fewer contacts (mean: 3,4 contacts) due to their early detection of peripheral obstacles than those with less peripheral perception (mean: 9,7 contacs). Patients with better VA required less time and less head movements to pass the maze. Conclusion Recordings and measurement of visual function and formation into groups allowed us evaluation of individual coping strategies. Hence potential benefits of epiretinal prostheses could be evaluated by comparing pre‐ and postoperative values.