Be careful with your first born children. They are more likely to be short-sighted than their younger siblings. Scientists at Cardiff University, analyzing health records from 89,000 British people aged 40-69 have found that first borns were 10% more likely to suffer from short-sightedness. They were also 20% more likely to suffer from severe myopia.
Why are these statistics true? The researchers believe that parents tend to spend more time overseeing their first child’s education, and that they give younger children more freedom to play outside and less time staring at books.
Dr. Jeremy Guggenheim of the Cardiff School of Optometry and Visual Sciences said, “Children with an earlier birth order do relatively better at school owing to parents investing more time, effort and/or resources in educating children with an earlier birth order.”
He continued, “Greater educational exposure in earlier-born children may expose them to a more myopiagenic environment; for example, more time doing near work and less time spent outdoors. 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.”
Interestingly, others have been doing similar studies. In China, where 80% of teenagers are short-sighted, authorities have been looking into creating transparent classrooms so that children get more natural light. Researchers have found that even an extra 40 minutes a day in sunshine will improve eyesight.