Right Under Our Noses: Why First-Born Kids Are More Likely To Be Nearsighted

INQUISITR.COM / Science
By Dawn Papple
Published on: 2015-10-08T23:56:42

Nearsightedness is increasing in younger generations and is most common among first-born children, but why? The reason has been right under our noses this whole time. Nearsightedness — also known as myopia — is a leading cause of visual impairment and a very important public health issue, experts say. A new study, published in JAMA Opthalmology, explains why researchers led by Jeremy A. Gugenhenheim, Ph.D, of Cardiff University, believe that nearsightedness is directly linked to the extra investment into educational activities like writing and reading.

The team says that extra time spent doing educational “near work” like reading and writing at a younger age could be causing the growing incidence of nearsightedness. It seemed plausible that first-born children might be more likely to be nearsighted, because their parents or caregivers had more time to invest in this “near work” with their first-born children. After all, parents of one child don’t have to split up their educational time with multiple children. Parents, according to Medical News Today, have a tendency to put more resources and educational time into their first-born kids, and this is why first-born kids tend to have better achievements in school.

Could this also be causing nearsightedness?

The researchers looked at over 89,000 U.K. Biobank participants aged 40- to 69-years-old with no history of eye disorders. First-borns were more likely than their siblings to have nearsightedness. The authors explained the link between nearsightedness and birth order.

“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.”

In fact, birth order was associated with both myopia and high myopia and the risk for nearsightedness got lower and lower for each subsequent child, like a dose response. It’s not just split finances and therefore subsequently less quality nutrition either, because when the team adjusted for education, the “apparent dose response was abolished.” This further supports the idea that nearsightedness is caused by “reduced parental investment in education of children with later birth orders in their relative protection from myopia” though the researchers were clear that the study design was not capable of actually establishing a causal link.

Previously, Inquisitr reported that other research indicates that children who rarely play outdoors are more inclined to nearsightedness and spending time outdoors can fight genetic predispositions for nearsightedness. Researchers in Taiwan took a group of elementary school students who usually stayed inside for their daily breaks and had them spend 80 minutes outside everyday. Another group of children acted as a control. Those children were allowed to stay inside as they always had. One year later, all of the students were given an eye exam and significantly fewer children who were forced to spend 80 minutes outside became nearsighted or started to become nearsighted compared to the control school.

These findings — coupled with the newer findings that educational investment is linked to nearsightedness — could be utilized together to help our first-born children have the best of both worlds by continuing to teach “near work,” but being sure to take long outside breaks so that the eyes can practice seeing greater distances.

[Photo via Pixabay]