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

Abstract

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. 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. For all tasks combined, a significantly shorter viewing distance was observed for the ultra-Orthodox group (36.2± 7.0cm) 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± 7.7cm vs. 41.3± 8.1cm, 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. 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.