When you were little and curled up with a good book, your parents might have scolded you with: "Turn on the light. You're going to ruin your eyes!" Well, it turns out that your parents were wrong about that.

Throughout your life, you've probably heard your fair share of eye care advice. But which "facts" are really true and which are not? Let's take a look at some commonly held beliefs about eye care and see what the experts have to say about them.

Reading in dim light will harm your eyes

Not true, according to Dr. Rohit R. Lakhanpal, board certified ophthalmologist and vitreoretinal surgeon at Union Memorial Hospital in Baltimore, Maryland. "This is a common misconception. Reading in dim light may cause some eye strain and dry eye, but [it's] not harmful and has no long-term effects."

If you cross your eyes, they could stay that way

"Not true," Dr. Lakhanpal says. In rare cases, the eyes may be slow to uncross, but this is only in children who already have an eye alignment disorder that shows up when they are sick or tired.

Children outgrow crossed or misaligned eyes

Dr. Lisa Schocket, board certified ophthalmologist at Baltimore's Union Memorial Hospital, says no, and Dr. Lakhanpal agrees: "[It is] important for these kids to be evaluated promptly. Unless it is forced to do the work, the misaligned eye will not develop proper vision."

Using computers can damage your eyes

Not so, says Dr. Lakhanpal. "The issue here is the fact that most people sit at their computers in an 'intermediate' distance between their far distance vision and their reading distance." This distance can lead to eye strain and dry eye (just as reading in dim light can), but it does not cause any long-term effects.

Wearing sunglasses when outside can prevent damage to your eyes

Yes, but only if the glasses have UV-a and UV-b protection, says Dr. Lakhanpal. "Ultraviolet rays increase the risk of intraocular tumors as well as macular degeneration."

Eating carrots can improve your vision

Well, yes and no: Carrots are rich in vitamin A, which is important for eye health, and "studies show that while taking vitamin A can reverse poor vision caused by a deficiency, it will not strengthen eyesight or slow decline in people who are healthy," says Dr. Lakhanpal.

Wearing eyeglasses will cause you to become dependent on them

"If you need glasses, you should wear them," Dr. Schocket says. Dr. Lakhanpal agrees. "Wearing eyeglasses will not make your eyes worse. Some refractive errors will worsen as you age, but wearing glasses is never the cause. Also, if you're used to clear vision when you wear your glasses, it will seem like your eyes are worse when you take [the glasses] off."

Wearing poorly fitted glasses or contact lenses can damage your eyes

"Poorly fitted contact lenses, specifically if they are too tight on the surface of the cornea, can cause dryness of the corneal surface and increase the risk of infection and scarring," Dr. Lakhanpal says. "Poorly fitted glasses may change the prescription, thus making the vision blurry."

Taking care of your eyes is important to good vision, and separating the myths from the truths can help you see everything more clearly.

Published on March 13, 2009; updated on May 30, 2014.

Margaret H. Evans

Freelance writer Margaret H. Evans lives in Bountiful, Utah, with her husband and four children. She has been writing and editing professionally since 1989. Her work has appeared in newspapers, magazines and online.