Reading speed and the perceptual span in patients with macular disease

Abstract

This presentation describes the results of a longitudinal assessment of the perceptual span, eye movements and reading speed in a group of patients with macular disease (MD). Eighteen patients with MD were recruited. All patients had developed a scotoma in their second affected eye in the 2 weeks prior to recruitment. Patients were assessed within 2 weeks of recruitment and again 3–12 months later. Eye movements were recorded whilst reading MN-Read style sentences using an infra-red gazetracker. Perceptual span was closely related to reading speed at the first (r2=0.53, p<0.001) and the second visit (r2=0.72, p<0.0001). In some patients the perceptual span changed by as much as two letters. Changes in the perceptual span were strongly related to change in reading speed (r2=0.43, p<0.005). These results lend support to the hypothesis that a reduced perceptual span is one cause of impaired reading in patients with macular disease. These results are relevant to the development of rehabilitation and training programs for patients with macular disease.