Firstborn children may have a slightly higher risk of becoming nearsighted later in life, compared with later-born siblings, new research suggests.
In the study, researchers looked at birth order and nearsightedness in about 89,000 people, ages 40 to 69. The investigators found that firstborns were 10 percent more likely to be nearsighted than were later-born participants, BBC health reported.
Firstborn individuals were also 20 percent more likely to be severely nearsighted than later-born individuals, the investigators found.
However, the researchers adjusted their results for education levels, such as the highest educational degree the people had attained, it turned out education accounted for about 25 percent of the link between birth order and the risk of nearsightedness.
This result suggests that parents may be more invested in the education of their firstborn children for example, spending 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.
Previous research has suggested that the older children in a family do relatively better at school because parents invest more time, effort and resources in those kids’ education.
This is why other researchers have also suggested that the link between birth order and a person’s risk of becoming nearsighted could be explained by educational attainment.