Early Myopia onset tied to risk of high myopia later on: JAMA

The risk of developing high myopia is relatively high among children with myopia onset at a young age, while each year of delay in the age of onset substantially reduces the chance of developing high myopia in adulthood, according to recent research published in JAMA ophthalmology.

The development of high myopia carries risks of irreversible blinding complications including glaucoma, retinal detachment, and myopic maculopathy. The World Health Organization defines myopia as a condition in which the spherical equivalent objective refractive error is ≤ –0.50 diopter (–0.50 D) in either eye. However, in this study, researchers classified high myopia as the spherical equivalent of −6.00 diopters or worse determined by cycloplegic refractions.

"It is widely acknowledged that the earlier the age at onset [of myopia], the greater the percentage of the population with high myopia," says Y Hu, the lead author of the study.

Inhis population-based prospective cohort study, Hu and his colleagues recruited twins aged 7 to 15 years, while follow-up visits were completed annually. Data were obtained from the Guangzhou Twin Eye Study, which began in 2006 in China.

Atotal of 443 individuals were included in the analysis and the majority (55.8%) were female. Data showed a mean (SD) age of myopia, onset was 11.7 (2) years. Over the course of the study, 54 (12.2%) developed high myopia in adulthood (age 17 or older).

The researchers came to the following findings-

Among participants with age at myopia onset of 7 or 8 years, 14 of 26 developed high myopia in adulthood

Among those with onset at 9 years of age, 12 of 37.

Among those with onset at 10 years of age, 14 of 72.

Among those with onset at 11 years of age, 11 of 78.

Among those with onset at 12 years or older, 3 of 230.

The results highlight the need for implementation of myopia prevention strategies, such as increased outdoor time, the authors argued.

Finally, they concluded that "The risk of developing high myopia is relatively high among children with myopia onset at a young age."