The Danish version of the Radner Reading Chart: design and empirical testing of sentence optotypes in subjects of varying educational background.

Abstract

To develop 28 short texts to be used as sentence optotypes in a Danish version of the Radner Reading Chart for the measurement of reading acuity and speed. Forty-six short texts of comparable lexical and grammatical difficulty were constructed. The short texts were tested together with two longer reference texts in 100 persons with visual acuity 6/6, of which 50 were university students (age: 24.7 ± 3.1 years, 36% males) and 50 were blue-collar workers (37.2 ± 13.4 years, 54% males). Study parameters were mean reading speed and error rate per participant, and mean reading time, variance and number of errors per short text. The students read the short texts faster than the blue-collar workers (184 ± 21.4 words per minute (wpm) versus 163 ± 26.3 wpm, p < 0.0001). There was a high correlation between the reference texts and the short texts [Pearson's correlation coefficient = 0.89 (95% CI 0.83-0.92)]. The mean reading time for each of the short texts ranged from 4.4 s to 5.8 s with a mean of 4.96 ± 0.35 s, and the median number of errors was eight. Twenty-eight short texts were selected for sentence optotypes with mean reading times between 4.6 s and 5.2 s, a mean standard deviation of 1.2 s or less and a number of errors of 17 per 100 persons or less. Reading time uniformity in the Danish version of the Radner Reading Chart was comparable to that of the original German version. Education had an influence on reading performance that may warrant stratification for this parameter when reading tests are used in clinical trials.