Objective quantification of viewing behaviours during printed and electronic tasks in emmetropic and myopic ultra-Orthodox Jewish men

Abstract

Purpose: Ultra-Orthodox Jewish men are known to have a high prevalence of myopia, which may be due to intense near-work from an early age. This study objectively assessed near-viewing behaviours in ultra-Orthodox and non-ultra-Orthodox men in Israel for different tasks.

Methods: Ultra-Orthodox (n = 30) and non-ultra-Orthodox (n = 38) men aged 18-33 years participated. Autorefraction, visual acuity, height and Harmon distance were measured. An objective range-finding sensor was mounted on their spectacles while they performed four 10-min tasks in a randomised order: (1) reading printed material, (2) writing printed material, (3) passive electronic and (4) active electronic tasks. Near-viewing distance and the number of viewing breaks were calculated for each task. Statistical analyses included Student t-tests and the Mann-Whitney test between groups and repeated measures ANOVA or Friedman between tasks.

Results: For all tasks combined, a significantly shorter viewing distance was observed for the ultra-Orthodox group (36.2 ± 7.0 cm) than for the non-ultra-Orthodox group (39.6 ± 6.7 cm, p < 0.05). Viewing distances for the passive reading and electronic tasks were shorter for the ultra-Orthodox group (36.9 ± 7.7 cm vs. 41.3 ± 8.1 cm, p < 0.03 and 39.0 ± 10.1 vs. 43.9 ± 9.3, p < 0.05, respectively). Viewing distances were significantly different between all four tasks, with writing having the closest distance. No correlation was found between working distance and spherical equivalent or Harmon distance. However, a significant correlation was found in the ultra-Orthodox group between working distance and height for each task (p < 0.04, R < 0.42 for all). There was no difference in the number of viewing breaks between the groups.

Conclusion: When reading a book and viewing an iPad, ultra-Orthodox men demonstrated a closer objective working distance than non-ultra-Orthodox men. This shorter viewing distance may contribute to the high prevalence and degree of myopia in this population.

Keywords: behaviour; myopia; objective working distance.