Contrary to the view that myopia stabilises at around age 15-16, a new Australian-based study has found it can develop and progress in more than a third of adults as well.

Using patient data from the Raine Study, a cohort study of patients born in Perth, Western Australia, between 1989 and 1991, 831 participants' eyes were examined at ages 20 (baseline) and 28 years. Of those without myopia or high myopia at ages 18-22, 14% (95% CI 11.5%-17.4%) proceeded to develop myopia and 0.7% (95% CI 0.3%-1.2%) high myopia within the eight-year period. Overall, 37.8% of participants had a "myopic shift", a change of 0.5 diopters or greater, in at least one eye and 22% had a myopic shift in both eyes, reported researchers in Jama Ophthalmology.

"With younger generations increasingly pursuing postgraduate education, we may expect more at-risk young adults to develop myopia in their 20s or early 30s," wrote authors, led by Dr Samantha Lee of the Lions Eye Institute in Perth and colleagues. "Even in non-university students or graduates, individuals are likely to start their first full-time occupation in or just prior to their 20s, and the rise in indoor occupations will inevitably result in the development or progression of myopia in a substantial proportion of the population."

Previous myopia studies on young adults have been limited and selective, said researchers. "A main strength of the current study is the large sample of community-based young adults, rather than recruiting participants from universities or myopic cohorts, as has been done in previous studies."

The new study concurred with others finding that the incidence of myopia was significantly associated with parental myopia and East Asian race, and with less sun exposure. Women were also found to be more likely to develop myopia than men. "This difference between young men and young women may reflect the modern societal push for higher education in girls and women, as reflected by the increasing proportion of women with higher education than men, and a tendency for women to work in indoor-based occupations in Australia,” said researchers. “These findings suggest myopia progression continues for more than one-third of adults during the third decade of life, albeit at lower rates than during childhood (and) the protective effects of time outdoors against myopia may continue into young adulthood.”