An interesting study from the UK, published in the Journal of the American Medical Association, states that first born children are more likely to have nearsightedness (myopia) than their younger siblings. Not only that, first born children were also more likely to have high myopia, a more severe form of nearsightedness. The potential reason? We'll get to that in a minute.
First, it's important to note that the incidence of nearsightedness or myopia has seen a marked increase over recent decades. Studies have shown that children of recent generations are increasingly more nearsighted than children of generations from 30 to 40+ years ago. The incidence and the severity of nearsightedness both have increased in children. One factor may be genetics. Another factor may be the increased amount of "near work" endured by children with the use of computers, tablets, smart phones, and portable video games. Another study showed that the amount of time spent indoors may affect nearsightedness. We've previously written how another study showed children who play outdoors are up to 50% less likely to develop nearsightedness over time.
In general, myopia is a public health issue. Not only does it place a financial burden on families and the health care system in general, but myopia also comes with risks for other complications. These may include the risk for vision loss directly through chorioretinal atrophy. Or includes risks indirectly through increased incidence of glaucoma, cataracts, or retinal detachments.
This recent study in the UK set out with the purpose of trying to identify a reason why firstborn children, in particular, were more likely to be nearsighted than their younger siblings. The reason is though-provoking, if not a little controversial. The researchers, after examining the evidence and adjusting for educational exposure factors, concluded that parents invest more education resources on first born children than on later born siblings--and this could be a key in why first born are more nearsighted. From strictly an observational perspective, this would lead to the association of increased education-related visual burden with increased incidence of myopia.
It's important to note there were a few key limitations of this study. First, there was a very wide age range in the participants which could potentially skew results. Secondly, the study used 2 primary educational criteria. First was the highest education qualification of the individual and the second was the age at which the full education was completed. But, critics of the study could argue that these criteria may not accurately reflect the educational experience and exposure used to make the observations of the data. Finally, no data was collected or evaluated on whether participants spent time outdoors or how much time outdoors.
Despite these limitations, the evidence does suggest first born children are more nearsighted than their younger siblings. What to do about this? Our advice is the same we always give to concerned parents. First, make sure your children are seeing the eye doctor for their comprehensive yearly eye exam--even when young and not complaining of vision problems. Second, advocate more time playing outdoors, less time on smartphones and tablets, and to take frequent breaks from the computer. If a child has myopia, the eye doctor may have tools at his or her disposal to help slow down progression in children that show a propensity for increasing nearsightedness year after year.
Dr. Beach