“Stop reading in the dark or you’ll ruin your eyes!” You may remember hearing this from your parents when you were curled up in bed as a kid with your flashlight and the book that you just couldn’t put down. Now, when you see other people or maybe even your own children reading away in dim light, you want to flip the light switch on or scold them in just the same way.
Dim light can certainly make you have difficulty focusing. It can also decrease how often you blink, making you uncomfortable because your eyes get dry and you squint for too long. However, the bottom line is that the effects of eye strain do not last. Once you return to good lighting, the effects go away.
There is simply no evidence proving that reading in the dark will ruin your eyesight forever. In the face of no clear scientific evidence, we have to look at what other sources we can find—expert opinions, related studies, and historical trends. The majority of ophthalmologists conclude that reading in dim light does not damage your eyes. Although reading in dim light can cause eye strain, with multiple temporary, negative effects, it is unlikely to cause a permanent change in the function or structure of the eyes.
One study did examine how the rate of blinking decreases during intense reading for patients with disorders that cause dry eyes, such as Sjogren’s Syndrome. In patients with Sjogren’s Syndrome, the decreased blinking and eye strain during reading can result in a temporary decrease in how well they can see. However, even in people with this condition, visual acuity improved when the patients stopped reading, again suggesting that the eyes return to their normal baseline when the strain is removed.
On the other hand, one review article on nearsightedness does conclude that “increased visual experiences,” such as reading in dim light or holding books too close to the face, could result in “impaired ocular growth and refractive error” (in other words, that reading in dim light might ruin your eyes). The primary evidence cited to support this claim is that nearsightedness is becoming more and more common, and that people who read more are more likely to be nearsighted. The author notes that this hypothesis is just beginning to “gain scientific credence.”
In examining this argument, we need to consider several important facts. First of all, association is not the same as causation. Just because more people who read a lot are nearsighted does not mean that the reading in dim light causes their nearsightedness. Even if they are linked, the key factor may be the amount a person reads, not the amount of light present where the reading takes place. Another important factor to consider is historical trends in lighting. Before the invention and widespread use of lightbulbs, people had to rely on reading by candlelight in dark rooms. Now, most of us have access to light for reading whenever necessary. We have never had better light for reading in the history of the world. In that sense, the fact that more people are nearsighted today, when the world is so well lit, does not support the idea that reading in dim light hurts your eyes.
Thus, our conclusion is that definitive scientific data do not exist to support or refute the claim that reading in dim light will ruin your eyesight, but the majority of experts believe (and common sense suggests) this is not true.
MYTH, HALF-TRUTH, OR OUTRIGHT LIE?
If you don’t shut your eyes when you
sneeze, your eyeball will pop out
Back in 1882, the New York Times told us that an unfortunate woman in Indianapolis actually had her eyeball explode after she sneezed while on a streetcar. Needless to say, the article describes that she was left in excruciating pain. In the current medical literature, we could not locate any documented cases of eyeballs subluxing, or popping out, after sneezing. On the other hand, vomiting hard and frequently enough can make your eyeball pop out. Certain types of trauma to the eye can also cause it to pop out. But for sneezing, we only have the sad, nineteenth-century story of the lady on the streetcar in our own town of Indianapolis. However, even if this were to occur, closing your eyelids would be unlikely to prevent the eyeball from coming out. The television show MythBusters did force someone to sneeze with their eyes open and noted that the person’s eyeballs did not pop out. This is just one anecdote and is not good enough evidence to prove that this is not possible, so this one is a half-truth. But it does help to remind us that this would be extremely unlikely and that, despite all of the horror stories, the eyes are very, very, very secure in their sockets.