New research suggests that firstborn children have a higher risk of developing nearsightedness than their younger siblings, CBS News reported.
Researchers from Cardiff University Eye Clinic in the United Kingdom found that the oldest child in a family is 10 percent more likely to be myopic than their later-born siblings. They were also 20 percent more likely to be severely nearsighted.
"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," Jeremy Guggenheim, the lead author, told NPR.
For the study, researchers collected and analyzed data from nearly 89,000 people between the ages 40 and 69. According to Time, researchers also looked at demographic data with behavioral information -- "one question asked how much time people spent outdoors, for instance-along with a detailed educational history and their ophthalmological past."
They found the connection between firstborn children and nearsightedness is education. Previous studies have found that parents tend to be more invested in the education of their firstborn children, but the recent finding suggests that they spend "more time reading or doing pages in workbooks with these children -- compared with their later-born children, which in turn may mean that firstborn children spend more time doing activities that promote nearsightedness," CBS News reported.
"Our study provides an extra piece of evidence linking education and myopia, consistent with the very high prevalence of myopia in countries with intensive education from an early age," Guggenheim of Cardiff University in the United Kingdom told CBS News.
The findings are detailed in the journal JAMA Ophthalmology.
