Characteristics of Reading Speed across Character Size in Relation to Visual Factors

Abstract

Reading performance is becoming a de facto standard for assessment of functional vision especially with respect to low vision function. This emphasis on reading performance has encouraged the development of new tests of reading vision such as the MNREAD Acuity Chart, Pepper Test, and Morgan Test. MNREAD Acuity Charts were designed so they can be used to quantify reading speed across a range of sentence character sizes in patients with normal and low vision. Previous studies have found that MNREAD measures of reading acuity, critical print size, and maximum reading speed are very useful indices for characterizing reading abilities in patients with low vision (Bane, Fish et al. 1996; Mansfield, Legge et al. 1996). However, the results of the MNREAD Acuity Chart can give the complete functional relationship between reading speed and character sizes. Clinically we have found that there is considerable differences in the rise (or slope) of the function from no reading ability to maximum reading ability. In addition, the length of the maximum reading speed plateau and whether the reading speed decreases at larger character sizes also has considerable variability. The significance of these characteristics of the reading speed curve to reading training has not been thoroughly investigated, but intuitively these characteristics would have significance in reading training. For example, the amount of magnification that is prescribed for reading would be more or less critical depending on the slope of the reading speed curve and the length of the maximum reading speed plateau. Also, if visual factors influence the reading speed curve than it might be possible to design rehabilitation training protocols to improve reading performance. The relationship between the reading speed across character sizes curve and visual function were examined to establish which visual factors influence the characteristics of the reading speed curve.