Purpose: Arabic is ranked as the 5th spoken language worldwide, yet there is no standardized chart of reading acuity in Arabic. This study aims to develop and validate the first standardized Arabic continuous text near visual acuity chart, the Balsam-Leat (BL) chart.
Methods: Forty-five previously validated sentences (J. Optom, in press, 2016) were used to construct 3 versions of the new chart. Bilingual adults (N=86) aged 15 to 59 years with normal vision took part. Reading speed and accuracy were measured with audio-recordings for the three BL charts and three English charts (MNREAD, Colenbrander and Radner). Outcomes were maximum reading speed in standard words per minute (SWPM) and reading acuity (RA). ANOVA was performed to compare RA and SWPM, Bland-Altman plots were used to analyze agreement, and linear regression was conducted to calibrate the BL charts for normal visual acuity (0.00 logMAR).
Results: Mean SWPM for the BL chart 1, 2 and 3 was 2.30, 2.28 and 2.28 log SWPM respectively and for the Colenbrander, MNREAD and Radner charts was 2.15, 2.22 and 2.15 respectively. Average RA for the BL charts was 0.62, 0.64 and 0.65 log point print respectively. There was a significant difference of RA between the three BL charts (repeated measures ANOVA, p < 0.05) and between the three English charts (p < 0.05). However, for the BL charts, this difference was not considered clinically significant (maximum of 0.035 log units difference between charts). The coefficient of agreement for RA between the BL charts was 0.054 (between 1 and 2), 0.061 (between 2 and 3) and 0.059 (between 1 and 3). Linear regression between the average RA for the BL charts and MNREAD chart showed that 0.7 log point size is equivalent to 0.0 logMAR and the new BL charts will be labelled accordingly.
Conclusion: The BL charts show good consistency for clinical use and will be a useful tool for measuring reading performance in Arabic for both research and clinical settings.