The effect of font and line width on reading speed in people with mild to moderate vision loss

The aim of this study was to evaluate the effects of print size, typeface, and line width on reading speed in readers with mild to moderate sight problems.

A total of 43 patients, most of whom had mild cataract or glaucoma with acuity 6/30 or better (median age = 72; range = 24-88 years), read aloud a selection of texts presented randomly in four sizes (10, 12, 14 and 16 point), for each of four typefaces [Foundry Form Sans (FFS), Helvetica (HV), Tiresias PCfont (TPC), Times New Roman (TNR)] at a standard line width of 70 characters and a viewing distance of 40 cm. A subset of letter sizes and typefaces were tested at two additional line widths (35, 90).

As expected, reading speed increased with print size from a median of 144 words min(-1) for 10-point text to 163 words min(-1) for 16-point text (repeated measures anova, p < 0.0001). There was also a significant effect of typeface with TPC being read about 8 words min(-1) faster, on average, than the other fonts (159 words min(-1) for TPC vs 151 words min(-1) for the other fonts, p < 0.0001). However fonts of the same nominal point size were not equivalent in actual size. When adjusted for the actual horizontal and vertical space occupied, the advantage of TPC was eliminated. There was no effect of line width (p > 0.3). Data from the present study were extrapolated to the general population over age 65. This extrapolation indicated that increasing minimum print size from 10 points to 16 points would increase the proportion of the population able to read fluently (>85 words min(-1)) from 88.0% to 94.4%.

This study shows that line width and typeface have little influence on reading speed in people with mild to moderate sight problems. Increasing the minimum recommended print size from 10 points to 14 or 16 points would significantly increase the proportion of the population able to read fluently.