According to a study published this month in the Journal of the American Medical Association Ophthalmology, firstborn children are 10 percent more likely to be nearsighted and 20 percent more likely to be severely myopic. The correlation between birth order and myopia shrank after the researchers adjusted data to take in account a person’s level of education, according to a National Public Radio article.
This isn’t the only study to find firstborns more likely to be nearsighted. A study conducted at Cardiff University in Wales examined data on more than 90,000 adults in the UK Biobank study who had had an eye exam. Previously, researchers had hypothesized whether firstborns were more likely to be nearsighted because they can be born much smaller. This was incorrect.
“In the current study we set out to test whether the link between birth order and myopia might have arisen because first-born individuals tend to spend slightly longer in full-time education than later-born individuals,” said Jeremy Guggenheim, the lead author of the study.
Could having multiple children affect their eyesight? Guggenheim and other researchers compared families with just two children to the complete database to figure this out. The relationship between nearsightedness and firstborns or later siblings was pretty much the same, according to the NPR article.
Other factors that could affect nearsightedness include higher income, education and less time spent outdoors. And of course, nearsighted parents have more of a chance at having nearsighted children.
Nearsightedness can cause problems while the children are in school. However once corrected, unless a person is severely myopic, nearsightedness is no longer an issue.