A recent study in the Journal of Ophthalmology compared the incidence of myopia (near-sightedness) from the early 1970’s to 2004. The researchers found a 66% increase in myopia over that 30 year time frame. A 66% increase! I get a little bored with statistics sometimes, but that is an amazing increase over such a short period of time. The study goes on to say that in the early 1970’s, about 25% of Americans had myopia and that in 2004 that number was near 46%.
Unfortunately, the study was strictly observational and didn’t investigate the causes of this drastic increase. There are many studies that conclude that myopia does have a genetic component. Myopic parents are more likely to have myopic children. But it’s impossible to predict the presence or degree of myopia in children based on the parent’s prescriptions.
We also know, through a number of studies, that environmental conditions play a role in the development of myopia. “Law school myopia” is a term that is used often. It relates to a famous study that showed law school students had a significant increase in myopia at graduation compared to their first day of graduate school. This increase, which isn’t exclusive to law school students, was attributed to the rigorous visual demands that extensive reading can place on a person’s visual system. When a person is reading, accommodation muscles are contracted to allow the eye to focus at close distances.
Having those muscles contracted for long periods of time will restrict their ability to relax and can translate into in an increase in near sightedness. Imagine you contract your bicep at full strength for two hours and then try to relax it….you most likely will not be able to move your arm back into its normal position. For some individuals, this may happen with their accommodation or near-focusing muscles.
Does the dramatic increase in computer use in modern times account for some of this myopia increase? More detailed studies on the causative factors will be needed. But, using the computer does require the same accommodation muscles that are seen in “law school myopia.” Obviously, we can’t stop using the computer or reading or studying. But there are some other things that can help.
Taking breaks from up-close visual tasks is key. Every 15-20 minutes look up from the reading material or computer and look at something far away—maybe a clock or a poster or painting. Allowing your eyes, for at least 30 seconds, to focus on that target at a distance will relax those accommodation muscles.
Still, the study is surprising. And hopefully it will trigger more studies on the causes for such a dramatic increase in myopia in the U.S.
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