Eye movements and reading in macular disease: further support for the shrinking perceptual span hypothesis

Reduced perceptual span is one factor which limits reading speed in patients with macular disease. This study measured the perceptual span and the number of saccades to locate a target in 18 patients with macular disease and seven control subjects on two occasions separated by up to 12 months. Perceptual span changed by up to two letters. Changes in perceptual span were significantly related to changes in reading speed (r2 = 0.43, p < 0.005), and were independent of changes in the number of saccades used to observe a target (r2 = 0.003, p = 0.62). These findings have important implications for the development of training programmes for patients with macular disease.