The measurement of time spent outdoors in child myopia research: a systematic review

The Role of Time Exposed to Outdoor Light for Myopia Prevalence and Progression: A Literature Review

Purpose

The development of myopia as a refractive disorder seems to hold multifactorial causes. Among others, increased time exposed to natural light outdoors is regarded as possible effective preventive measure against myopia development. The objective of this review is to analyse and summarize the evidence investigating the association between time outdoors and myopia prevalence and progression.

Methods

A review, restricted to articles published in the last ten years, was conducted. The literature search for the included articles was performed in the following databases: PubMed, the Cochrane Library, Web of Science and Scopus. If predefined inclusion criteria were met, the studies were further categorized and data were summarized and individually evaluated.

Results

Two cross-sectional studies, 7 prospective cohort studies and 3 intervention studies were reported in this review, representing the data of a total of 32,381 participants. The majority of the studies found an inverse association between myopia incidence/prevalence and increased time outdoors. The association between time outdoors and myopia progression on the other hand remains debatable; one recent randomized controlled trial indicating a protective value of increased time outdoors for further progression in myopic children.

Conclusion

In summary, increasing time exposed to outdoor light seems to be a simple and effective preventive measure to decrease myopia prevalence. Also, contrasting previous review work, it may represent a potential strategy for myopia progression control. Future investigation is necessary to better define and quantify outdoor time and its effects on myopia.

Novel Method of Remotely Monitoring the Face-Device Distance and Face Illuminance Using Mobile Devices: A Pilot Study

Specially developed software (app) was written for handheld electronic devices that uses the device camera and light detector for real-time monitoring of near-work distance and environmental lighting. A pilot study of this novel app employed children using tablet computers in a classroom. Measurements of face-device distance and face illuminance were obtained from two schools where tablets were used regularly. Children were divided randomly into a control group (CG) and intervention group (IG). The app was calibrated in a lab and configured to store average values every 20 seconds in a remote database. In both groups, the app recorded data only when a child's face was present in the camera image. The app darkened the screen for the IG when the face-device distance was shorter than 40 cm. The total mean face-device distance was 36.8 ± 5.7 cm in CG and 47.2 ± 6.5 cm in IG. Children in IG had to accommodate approximately 0.6 D less when using their devices. The mean classroom face illuminance was 980 ± 350 lux in School #1 and 750 ± 400 lux in School #2. The novel method of remotely monitoring and controlling the face-device distance and illuminance can potentially open new paths for myopia prevention and myopia control.