An investigation of reading as a measure for clinical visual assessment in normal and amblyopic vision

Abstract

This thesis investigates binocular reading performance in individuals with amblyopia and the contribution of motor and sensory functions to reading in amblyopes. Despite a considerable body of research on reading in individuals with amblyopia, little information available about reading performance when measured with standardised logarithmic charts under habitual binocular conditions. Further, there is limited research on the aspects underlying the associated reading difficulties. Therefore, this thesis is a novel investigation into reading in amblyopia and aspects related to this function. The thesis comprises five empirical studies exploring whether reading performance differs between amblyopes and visually normal controls. The comparability of logarithmic reading charts was examined on visually normal participants in study 1. The results suggest that these charts yield comparable outcomes. Study 2 explored reading performance in amblyopia and showed that reading in amblyopia is limited, relative to controls. Study 3 tested the effect of induced monocular blur on reading and revealed that the severity of monocular visual impairment adversely affects reading performance. Study 4 suggests that convergence insufficiency can affect reading but may not be a contributor to reading difficulties in amblyopes. Study 5 indicates impaired eye-movement control during reading in amblyopia, with word-length effect being more pronounced in amblyopes than among controls. Overall, these studies enrich our knowledge of reading performance in adults with amblyopia, shedding light on the visual aspects of this difficulty and highlighting the important areas to be addressed in future research.