Saturday, May 21, 2011

Take another look at these sayings about eyes

NASHVILLE, TENN. -- — It seems the world is full of mothers who fancy themselves amateur ophthalmologists.Who didn't grow up hearing admonishments such as "Eat your carrots. They're good for your eyes" or "Don't sit so close to the TV. You'll go blind."
We consulted with Dr. Mark Melson, assistant professor of ophthalmology at Vanderbilt University, to find out whether these famous sayings are true.
Saying: Wearing glasses makes your vision worse over time.
Myth: Eyesight can naturally degrade as you age, but wearing glasses does not damage vision or make the eyes dependent on them.
Melson said it's likely perception changes. People who have never worn glasses are accustomed to navigating a blurry world.
When seeing clearly through glasses becomes the new normal, their natural eyesight seems worse by comparison.
Saying: Eating carrots will improve your vision.
Myth: Carrots are rich in vitamin A, which is essential for sight. However, the small amount of vitamin A that's necessary to maintain good vision easily is achieved by eating a balanced diet. Many foods are rich in vitamin A, such as asparagus, apricots, nectarines, milk and cheese.
Though rare, Melson said consuming too much vitamin A has been linked to muscle weakness, nausea, vomiting and increased head pressure.
Saying: Babies can't see normally at birth.
Fact: Newborn babies can see little more than the difference between light and dark, Melson said.
While eyesight improves significantly during the following weeks and months, it's believed they don't develop 20/20 vision until age 2 or 3.
Saying: Looking directly into the sun will damage your eyesight.
Fact: The intensity of the sun's light damages cells that help people see. Other types of bright light, such as laser pointers, can have the same effect. Though it varies from person to person, injury can occur in a matter of seconds.
Saying: Reading in dim light weakens eyesight.
Myth: While reading in the dark can strain your eyes temporarily and give you a headache, it doesn't cause lasting damage.
Saying: Too much sex can make you go blind.Myth: Syphilis, a sexually transmitted disease, can cause blindness if it goes untreated. And Melson says that likely is how this myth originated.
On a modern side note, studies are under way to determine whether Viagra could be linked to a rare form of vision loss and blindness recorded among some men taking the drug. However, engaging in sexual relations will in no way damage your vision.
Saying: Sitting too close to the TV will damage your vision.
Myth: In the 1960s, some TV sets were found to emit excessive radiation, which is why many people grew up with their mothers telling them not to sit too close to the television.
While that's not an issue today, Melson said watching too much television -- or focusing your eyes on any one thing for a long period of time -- can strain the eyes and cause headaches. There's no lasting damage, though. Melson said if children habitually sit too close to the television, it could be a sign they can't see it from farther away and need to have their eyes checked.
Saying: Wearing someone else's glasses can damage your eyes.
Myth: A temporary headache or blurred vision may occur as eyes try to adjust to the incorrect prescription. Vision, however, won't be harmed in the long term.
Saying: If you cross your eyes, they'll stay that way.
Myth: An annoyed mother likely started this erroneous belief centuries ago.
The tiny muscles that control eye movement may get tired if you keep your eyes crossed for a long time, but they are highly resilient and won't become stuck.

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