“Don’t sit too close to the TV. You’ll ruin your eyes,” said every mom that ever existed. Since the 1960’s, parents all around the world have been telling their kids that sitting too close to a screen will cause them to go blind. This may be a myth. So why do parents continue to preach this possibly false claim to their kids? One reason is because of a little lie parents were telling that stuck around for too long, and the other is an error in the interpretation of causation. Lets see if there is any scientific evidence to suggest TV can cause you to go blind.
To start, I want to take you back to the 1960’s. Tube TV’s were the current form of entertainment. Unfortunately, back then, the technology was not very safe. An electron gun drew a picture on a phosphorus-coated glass and vacuum tubes supported the electronics. This emitted low amounts of x-rays. However, in one instance, the company General Electric had to recall a great number of tube TV’s because they were emitting excessive amounts of x-rays through the vents in the front of the TV’s. When this happened, mothers became very cautious about letting their kids sit too close to the TV due to a fear of possible x-ray exposure, so they told them they would go blind. The x-ray problem in TV’s was eventually fixed, but the little white lie stuck around.
The other reason parents continue to hassle kids about their proximity to the TV is the parent’s anecdotal evidence they receive when their child who sits a foot away from the TV needs glasses a year later. This does not prove causation. Actually, reverse causation seems more plausible in my opinion. For example, those who sit close to the TV probably already have a condition called myopia (nearsightedness). When the child needs glasses a year later, the parent falsely believes it was the TV that caused the myopia. Unfortunately for mom and dad, I took Science 200 and recognize there is no evidence that sitting close to a TV causes myopia. In fact current research is finding other causes to nearsightedness.
Though I could not find I study to disprove TV causing nearsightedness, I found an observational study that suggests it could be other factors. This study measured 13 possible predictors to childhood myopia in 4927 children aged 7 to 13. The predictors were measured by first observing whether the predictor was present in the subject (astigmatism magnitude, crystalline lens thickness, etc.). Basically, a predictor was a certain biological feature on or part of the eye. Then the researcher statistically correlated the predictors with whether or not the child had myopia. It turns out that the “spherical equivalent refractive error” showed the highest correlation to the myopia. Since it was an observational study, the researcher was only able to show a positive association between this certain biological feature of one’s eye (spherical equivalent refractive error), and the disease myopia, nothing causal.
This study has its limitations as well. Like I just mentioned, it is an observational study so there is no way of proving spherical equivalent refractive error caused the myopia seen in children. Also, the study was limited to the 13 predictors of myopia the researcher chose to observe. When I realized this, it made me wonder whether the researcher missed a predictor in her list of 13. You cannot measure something you do not think of, which is a definite limitation to this study design. Finally, the study’s population is children. It would not be accurate to extend these results to adults as well, who are also susceptible to myopia.
However, one thing I like about this study is the large sample size. Since it wasn’t an experiment, we can’t prove causation, but at least the large sample size allows us to extend the association to the population.
To answer my original question, I would propose an experiment that directly analyzes whether TV causes myopia. I would collect a large random sample of children in the same age group as the previous study, but then randomly assign them to a group that spends 5 hours a day in front a TV for a month, and a group that watches no TV for a month. I would then compare the groups with a matched pairs design by administering a “far away” reading test. This would allow a more causal relationship between TV and myopia to be formed.
So what does this all mean? Basically, no ophthalmology expert website that I could find believes TV causes nearsightedness, and this study I analyzed also does not recognize TV as a predictor. That is why setting up an experiment like I proposed may finally end the debate. As for now, I think whether you choose to sit close to the TV should depend on how much it means to you (like Andrew’s classic beer example). If sitting close to the TV is something you cannot live without, I would suggest you keep doing it since there is no evidence showing it to cause blindness. However, if you do not care where you sit, you might as well sit farther away due to the possible unproven risk of developing myopia. This will not only keep your parents quiet, but will guarantee your safety until more conclusive evidence is discovered.
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This semester we have had a couple pop quizzes on a hamster experiment that showed exposure to dim light at night—about the brightness of a TV—caused hamsters to show signs of depression. The same might be true for humans if our hippocampus’ are changed by light at night. But recently I found an article on Too much TV as a young adult may impair midlife cognitive function , it seems that there are a number of different studies with evidence on television’s affect on our bodies. Nearsightedness might just be another reason to cut the cord and limit TV usage.
Nearsightedness is a cliché that has been talked again and again, the TV is one of the main cause to nearsightedness in people’s common sense. However, the point you bring out is very interesting and surprising. The evidence is convincing and reasonable, and as long as sitting in a proper distance, the TV will not harm eyes that much.
Here is a link that I found about the TV and nearsightedness.
https://www.nlm.nih.gov/medlineplus/ency/article/001023.htm