PSYCHOPHYSICS OF READING .15. FONT EFFECTS IN NORMAL AND LOW-VISION

Purpose. Little is known about the effect of font on low-vision readin g. In this study, tile authors measured the influence of font in readi ng with normal and low vision. Methods. Reading acuity, maximum readin g speed, and critical print size (tile smallest print that carl be rea d with maximum speed) were measured in 50 normal subjects and 42 subje cts with low vision. Data were collected using versions of the MNREAD Acuity Chart printed with the Times (proportionally spaced) and Courie r (fixed-width) fonts. Results. Reading acuity scores obtained with Co urier were better than those obtained with Times for both normal (mean difference, 0.05 logMAR, P < 0.001) and subjects with low vision (0.0 9 logMAR, P < 0.001), Similarly, critical print sizes measured with Co urier were smaller than those measured with Times (mean difference, 0. 06 logMAR for normal subjects and subjects with low vision, P < 0.002) . Maximum reading speeds for normal subjects were 5% faster with Times than with Courier (P < 0.001), but for subjects with low vision, maxi mum reading speeds were 10% slower with Times than with Courier (P < 0 .05). For print smaller than the critical print size, the reading spee ds of normal subjects and subjects with low vision were substantially slower (by as much as 50%) for Times than for Courier. Conclusions. Th ere are small, but significant, advantages of Courier over Times in re ading acuity, critical print size, and reading speed for subjects with low vision. For normal subjects, the differences are slighter, with a n advantage in reading speed for Times. However, for print sizes close to the acuity limit, choice of font could make a significant differen ce in both normal and low-vision reading performance.