Department of Ophthalmology & Clinical Centre of Optometry, Eye Disease and Optometry Institute, Peking University People's Hospital, Beijing Key Laboratory of the Diagnosis and Therapy of Retinal and Choroid Diseases, Beijing, China.
Institute of Medical Technology, Peking University Health Science Centre, Beijing, China.
BMJ Paediatr Open. 2023 Apr;7(1). doi: 10.1136/bmjpo-2022-001835.
Near viewing distance (VD) and longer viewing times are associated with myopia. This study aimed to identify the font size and viewing time that guarantee the appropriate VD and pixels per degree (PPD) for children's online learning.
This cross-sectional study comprised two experiments. In experiment A, participants read text in five font sizes on three backlit displays (a personal computer, a smartphone and a tablet), an E-ink display and paper for 5 min per font size. In experiment B, participants watched videos for 30 min on three backlit displays.
The Peking University People's Hospital in Beijing (China) and the School of Ophthalmology and Optometry, Wenzhou Medical University (Zhejiang Province, China).
Thirty-five participants completed experiment A. Ten of them participated in experiment B.
VDs were measured by Clouclip. The corresponding PPD was calculated.
In experiment A, font size and display type significantly affected VD (F=149.44, p<0.001, ES (Effect size)=0.77; F, p<0.001, ES=0.37). VDs were >33 cm for all five font sizes on the PC, the tablet and paper and for 18-pt on the smartphone and 16-pt on E-ink. PPD for 16-pt on the PC, 14-pt on the tablet and all five font sizes on the phone were >60. In experiment B, VD increased over the four previous 5 min periods but decreased slightly on tablets and PCs in the fifth 5 min period. PPD was >60.
Children demonstrated different VDs and PPDs based on font size and display type. To ensure a 33 cm VD and 60 PPD, the minimum font size for online reading should be 18-pt on smartphones, 16-pt on PCs and E-ink, 10.5-pt on tablets and 9-pt on paper. More attention should be given to children's VD with continuous video viewing of more than 25 min.
ChiCTR2100049584.
近距阅读距离（VD）和较长的阅读时间与近视有关。本研究旨在确定儿童在线学习的适当 VD 和每度像素（PPD）的字体大小和阅读时间。
这项横断面研究包括两项实验。在实验 A 中，参与者在三种背光源显示屏（个人计算机、智能手机和平板电脑）、电子墨水显示屏和纸张上阅读五种字体大小的文本，每种字体大小阅读 5 分钟。在实验 B 中，参与者在三种背光源显示屏上观看视频 30 分钟。
北京大学人民医院（中国北京）和温州医科大学眼视光学院和视光医院（中国浙江省）。
35 名参与者完成了实验 A。其中 10 人参加了实验 B。
VD 通过 Clouclip 测量。相应的 PPD 被计算出来。
在实验 A 中，字体大小和显示类型显著影响 VD（F=149.44，p<0.001，ES（效应量）=0.77；F，p<0.001，ES=0.37）。对于 PC、平板电脑和纸张上的所有五种字体大小以及智能手机上的 18-pt 和电子墨水显示屏上的 16-pt，VD 均大于 33cm。PC 上的 16-pt、平板电脑上的 14-pt 和手机上的所有五种字体大小的 PPD 均大于 60。在实验 B 中，VD 在之前的四个 5 分钟期间增加，但在第五个 5 分钟期间略有下降在平板电脑和 PC 上。PPD 大于 60。
儿童根据字体大小和显示类型表现出不同的 VD 和 PPD。为了确保 33cm 的 VD 和 60 PPD，智能手机上的在线阅读最小字体应为 18-pt，PC 和电子墨水应为 16-pt，平板电脑应为 10.5-pt，纸张应为 9-pt。对于超过 25 分钟的连续视频观看，应更加关注儿童的 VD。
ChiCTR2100049584。
