Font effects on reading parameters: comparing Radner Reading Charts printed in Helvetica and Times Roman

Purpose To investigate the effect of font choice on reading parameters by using the RADNER Reading Charts printed in two fonts (Helvetica vs. Times Roman) equalized in terms of x-height. Methods This is a cross-sectional study of 40 participants with healthy eyes (18 to 60 years of age; mean: 42.13 +/- 12.28 years). Reading performance was evaluated binocularly with RADNER Reading Charts printed in either Helvetica Neue (T1) Roman sans serif (Adobe) or Times New Roman PS Roman serif (Adobe). The test distance was 40 cm. Reading charts were presented in random order. Reading acuity (RA), mean reading speed of all sentences read (MEAN-ALL RS), mean reading speed from 0.8 logRAD to 0.3 logRAD (MEAN-RS), maximum reading speed (MAX-RS), and critical print size (CPS) were compared. Results The RA values obtained for the Helvetica and Times Roman fonts (in full logarithmic units of 0.1 logRAD) did not differ between the two fonts (mean for both fonts: - 0.128 +/- 0.064 logRAD; 95% CI for both: - 0.148; - 0.107 logRAD). The differences in all other reading parameters between the two fonts were small and not statistically significant. The analyses revealed narrow confidence intervals and good coefficients of reliability. Except for the CPS (r = 0.49) and RA (equal for Helvetica and Times Roman), the correlations for all parameters were high, ranging from r = 0.92 to r = 0.98. Conclusion The equivalent reading performance obtained with Helvetica and Times Roman (when equalized in x-height and layout) makes these font types interchangeable as standards for reading charts.