A research team from China and the UK employed a new approach to determine environmental influences on myopia risk through a wearable, computerized device attached to spectacle frames. The investigators also developed a visual behavior index to summarize the overall impact of working distance and light intensity on spherical equivalent refraction.

Compared with traditional approaches that assess a single dimension of an environmental factor in isolation—working distance, for instance—this study paired working distance with light intensity to integrate independent visual behavior features, the researchers explained.

Their study enrolled 179 fourth grade students who for a week wore a device called a ClouClip that attaches to spectacle arms to measure working distance and light intensity. The ClouClip is programmed to measure working distance every five seconds and light intensity every 120 seconds. All participants underwent a comprehensive ocular exam, including an ocular health assessment and cycloplegic autorefraction in both eyes. Mean standard deviation spherical equivalent refraction was 0.22±1.18D.

The researchers found that working distance and light intensity were positively associated with the spherical equivalent refraction. However, their magnitude of effect varied based on the relative level between them. When working distance and light intensity were separated, the detrimental myopia threshold was approximately 40cm for working distance and 6300lux for light intensity.

Also of note: the study’s visual behavior index was also significantly and positively associated with the spherical equivalent refraction.

“Our novel approach might provide a useful tool to investigate the role of environmental risk factors in myopia research, as well as a practical tool to predict myopia development and progression in practice,” the researchers wrote in their paper.