Distribution and Time Trends of Refractive Errors in Japanese Spectacle Wearers

Area of Science:

• Ophthalmology
• Public Health
• Optometry

Background:

• Refractive errors are a significant global health concern.
• Understanding their distribution and progression is crucial for effective management.
• Previous studies often lack large-scale, nationwide data on refractive error trends.

Purpose of the Study:

• To analyze the distribution and temporal trends of refractive errors in Japanese spectacle wearers.
• To identify age- and sex-specific patterns of refractive error progression.
• To provide data for public health initiatives and clinical interventions.

Main Methods:

• Analysis of a nationwide database of 4,525,689 spectacle wearers (ages 6-35) in Japan (2021-2023).
• Calculation of spherical equivalent (SE) and assessment of its distribution by age, sex, and region.
• Estimation of annual refractive error progression rates using linear and generalized additive mixed models.

Main Results:

• Myopic shift observed with age, stabilizing around 29-30 years (median SE: -3.3 to -3.5 D).
• Hyperopia prevalent at age 6 (~30%) but decreased by teenage years.
• High myopia (≤ -6 D) found in 1.3% of children <10 years; rapid progression (-1.1 D/year) at age 7.
• Myopia progression decelerated between ages 9-19, with a notable inflection point at 12 years in females.

Conclusions:

• Myopia progression significantly impacts children aged 6-7 years.
• Early surveillance and timely interventions are essential to control myopia progression.
• Findings provide valuable insights into refractive error epidemiology in Japan.