In the first large-scale population-based study to evaluate the associations between lens thickness and lifestyle, Japanese researchers found almost half of Tokyo’s preschoolers are myopic.

Researchers at Tokyo’s Keio University School of Medicine collected the ocular parameters, lifestyle and refraction data of nearly 2,000 Japanese children aged 3-14 years. Associations between these factors demonstrated axial length elongation seems to slow around 12 years old, while near work and lens thickness association appears to vary with near work type. Specifically, time spent using digital devices is positively associated with lens thickness, said researchers, while time spent reading is negatively associated. “We would like to evaluate whether the lens thickness changes with the type of near work and to objectively measure lifestyle factors, including the time spent outdoors, in a future study, because the underlying reasons for the findings remain uncertain,” they wrote.