Understanding low-vision reading

Abstract

Reading difficulties usually accompany low vision. Historically, little research has been devoted to the role of vision in reading. This is due in part to an emphasis on cognitive factors in normal reading and in part to the now discredited view that impaired vision should be conserved rather than aggravated by prolonged tasks like reading. Recently, psychophysical methods have been used to study the role of vision in reading. Normal performance has been evaluated for stimulus variables likely to be important in low-vision reading. Comparable low-vision measurements have been made and departures from normal analyzed. Examples to be discussed include the effects of character size, contrast, and blur. Despite fears that the heterogeneity of low-vision conditions might be too great to yield general principles, these experiments have uncovered distinctions, such as the presence or absence of central vision, that predict reading performance. Moreover, the visual requirements of reading are modest and within the capacity of most low-vision subjects. Research of this kind will establish optimal stimulus conditions for low-vision reading, best reading performance that low-vision individuals may hope to achieve, methods for clinical assessment, and principles for designing new low-vision reading aids.