The response of the accommodation system to digital and print images

Background: The transition from traditional print medium to a digital medium may affect the accommodative response (AR) because of the differences in the characteristics of the targets viewed. Aim: This study investigated how the accommodation system responded to targets displayed on a tablet computer compared to that on paper. Setting: The study was conducted amongst students at a university in South Africa. Methods: Using a quantitative, cross-sectional study the AR, amplitude of accommodation (AA), and accommodative facility (AF) were assessed with a target on an iPad and a paper-based one on a non-probability sample of 30 university students. Data was analysed using descriptive statistics and Bland Altman plots. Results: The median AR with a tablet was +0.25 dioptre (D) compared to +0.21 D with the paper-based target. This difference was neither statistically nor clinically significant. The median AA with a tablet computer target was 10.59 D and 9.85 D with a paper-based target. While this difference was statistically significant ( p = 0.002), Bland Altman analysis revealed comparable measurements with both types of targets. Both Wilcoxon Signed Ranks Test ( p = 0.462) and Bland Altman analysis found comparable medians for AF obtained with a target on paper (7.67 cycles per minute [cpm]) and a target on the tablet computer (7.17 cpm) to be comparable. Conclusion: The accuracy, strength and flexibility of accommodation were comparable for tablet computer and paper-based targets.