Firstborns more likely to be nearsighted

Researchers believe that the cause may stem from an educational push that is oftentimes seen in firstborns more. A firstborn is 10% more apt to be myopic than its siblings that follow, and 20% more likely to be diagnosed as severely nearsighted, said researchers.

When the researchers adjusted the data to account for people’s level of education, the correlation between birth order and myopia shrank.

Such children tend to spend less time practicing outdoor physical activities and more time focusing on personal education.

Of all the people in the new study, 30 percent were nearsighted, the researchers said. Moreover, after adjusting for other factors with his colleagues he found that 20 percent were more likely to show symptoms of severe nearsightedness.

The survey was carried out from about 90, 000 adults with ages from 40 to 69.

Myopia-the scientific term for nearsightedness-is a growing concern in fast-developing countries like India and China, where rates of childhood nearsightedness have skyrocketed in the past couple of generations.

Higher income, education and less time spent outdoors also increase the risk of myopia, other studies have found. And nearsighted parents are more likely to have nearsighted kids.

Indeed, the researchers say, “Greater educational exposure in earlier-born children may expose them to a more myopiagenic [factors causing myopia] environment; for example, more time doing near work and less time spent outdoors”, noting that it is the parents who are at fault for the aggressive education.

There’s a lot of worry about nearsightedness in children, with rates soaring in Southeast Asia as populations become more urban and educated.

Apart from the younger siblings being less at risk for myopia, Guggenheim and the team also kept on the lookout for other influencing factors. In a school setting, that child has access to books, iPads, toys, and chalkboards, all of which involve straining the eyes. An original hypothesis suggested that it was related to the tendency of firstborn children to be a little lighter than average at birth. “Our findings that statistical adjustment for indices of educational exposure partially attenuated the magnitude of the association between birth order and myopia, and completely removed the evidence for a dose-response relationship, therefore support the idea that reduced parental investment in children’s education for offspring of later birth order contributed to the observed birth order vs myopia association and produced the observed dose-response relationship”, the authors write. A new study suggests education plays a part.