Visual function and reading disability: an optometric viewpoint.

Recent research has identified a low-level transient visual system deficit in patients with reading disability. This deficit has been shown to have consequences on higher level perceptual and cognitive functions, including reading. This new information provides optometrists with a theoretical framework to expand the understanding of the relationship between vision and reading. In this paper, traditional concepts are described and an extensive literature review is provided. The impact of these processing deficits on reading performance is discussed based on metacontrast masking and foveal-parafoveal sequential attention models of reading. Clinical implications of transient system function in other clinical entities are also provided.