Myopia may progress earlier – and continue later – than conventional clinical assumptions suggest, according to an analysis of more than 4.5 million spectacle wearers in Japan.
Using prescription records from 434 stores operated by a nationwide optical chain, researchers based at The University of Osaka, Japan, mapped refractive error from childhood to young adulthood. The cross-sectional dataset covered 4,525,689 people aged 6–35 years who purchased spectacles between September 2021 and August 2023, representing approximately one-third of Japan’s optical market.
Spherical equivalent (SE) shifted progressively in the myopic direction with age. Median SE stabilized at approximately 30 years in men and 29 years in women, reaching −3.3 D and −3.5 D, respectively. This later plateau contrasts with earlier longitudinal studies suggesting that myopia generally stabilizes between 18 and 21 years, and supports growing recognition that clinically meaningful progression can continue throughout the 20s.
The study also revealed how rapidly the refractive profile changes during childhood. At age six, hyperopia accounted for approximately 30 percent of prescriptions, but declined sharply and became negligible by early adolescence. Meanwhile, the proportion of patients with high myopia – defined as SE of −6.0 D or worse – increased from around age 10. High myopia was already present in 1.3 percent of spectacle-wearing children younger than 10 years.
To examine progression over time, the researchers analyzed repeat purchases from 133,483 individuals. The fastest median myopic progression occurred at age seven, reaching approximately −1.1 D per year in both sexes. Progression then decelerated, with significant changes in trajectory identified at ages nine and 19 in men, and at nine, 12, and 19 in women. By age 20, progression generally slowed to less than −0.3 D annually.
Although age-related patterns were broadly consistent across Japan, the analysis also identified regional and sex-related differences. Men tended to be more myopic at younger ages, whereas women showed greater myopia after approximately age 26. Regional variation may reflect differences in outdoor exposure, climate, lifestyle, or generational behavior, although these factors were not directly measured.
The study authors caution that spectacle purchasers are not necessarily representative of the general population and so likely overrepresent symptomatic or rapidly progressing myopes. The 2021–2023 study period also coincided with pandemic-related changes in screen use and outdoor activity, and so these environmental shifts could have potentially accelerated global myopia progression. The analysis also lacked information on corneal status, lifestyle, and previous ocular procedures.
However, the scale of the dataset offers a detailed view of real-world refractive management in Japan, with the findings placing the most urgent surveillance window at six to seven years of age, while reminding clinicians that myopia management may need to extend well beyond adolescence.
