Reading acuity in children: evaluation and reliability using MNREAD charts

PURPOSE: To study reading acuity in children and assess the reliability of its measurement using the Italian version of the MNREAD reading chart. METHODS: One hundred sixteen children from grades 3 to 8 with normal near vision were tested at a pediatric eye care institution in northeastern Italy. Visual acuity was evaluated with Early Treatment Diabetic Retinopathy Study (ETDRS) charts and reading acuity with MNREAD charts. Examination with charts 1 and 2 by the same examiner in the same visit were used as test-retest measurements. RESULTS: Mean improvement of performance from grades 3 to 8 was approximately 1 line for ETDRS acuity and 1.5 sentences for reading acuity and critical print size. Mean maximum reading speed increased from 96 to 167 words/minute. Regression analysis showed that a stable reading speed was obtained throughout sentences of decreasing size up to the critical print size. Measurement error, expressed as 95% limits of agreement, was +/- 0.136 logarithm of the minimum angle of resolution (logMAR) and +/- 0.142 logMAR for ETDRS acuity and reading acuity, respectively. Critical print size had the lowest reliability (+/- 0.193 logMAR). Maximum reading speed limits of agreement were +/- 0.077 logarithm of words per minute (logWPM), or a 19% change in words per minute. There were no detectable effects of grade and refractive error on measurement errors. CONCLUSIONS: In children, MNREAD charts provide measurements of reading acuity as reliable as ETDRS chart measurements of distance acuity on a logMAR scale. They also provide highly reliable measurements of the maximum reading speed across all grades, independent of its noticeable increase.