"In America it's not an issue, because our diets have plenty of vitamin A," said Moscot.
Some foods can help eyes, however.
Dark green vegetables, such as spinach and broccoli, for example, contain lutein, which is found as a yellow spot in the retina, called the macula.
Rosen explained that these nutrients -- which can also be found in egg yolk -- can protect the macula, and may play a role in preventing macular degeneration, a condition in older adults where they lose vision in the center of the eye.
"It's probably important to encourage people to eat those sorts of foods," he said.
Answer: Sort of
Unless you are an unusually precocious child who has started reading the health section of our site, chances are that there's little that eye exercises can do for your vision.
Eye exercises are often used in the preteen and teenage years to help children with convergence -- bringing their eyes together for objects that are closer in. They're much less effective for adults.
"Typically in adults the system is pretty rigid," said Moscot.
"Focusing difficulties and convergence issues can be improved with eye exercises," he said, but noted that "it does take a commitment and it does take time. In some adults those exercises are helpful, but not all and those are variable."
However, eye exercises that are promoted as helping people get rid of glasses -- known as Bates exercises -- have not been shown to help.
"It's not a scientifically supported method," said Moscot.
Rosen said that while vision does deteriorate -- and exercises will not reverse that -- the exercises may have an effect on utility.
"A lot of it is learning how to use the vision that you have," he said.
An example, Rosen said, is that someone who had a defect in the center of the lens may be aided if they learn to look through other parts.
Rosen said he had some patients who are able to function with 20/400 vision (20/20 is optimal, 20/200 is legally blind).
"A lot of it is how you're able to utilize that sensory input that you get from the eyes," he said. "It may help them to utilize the vision they do have, especially if they've lost some vision."
"Using the correct pair of glasses for you does not make your vision worse. You don't grow more dependent on them," said Chang. The myth, he said, is based on the misperception that "if you were to wear glasses or contact lenses, that somehow changes the physiology of your eye, and that does not happen."
Natural aging and its effects on the eyes may have played a role in spreading this myth.
With age, peoples' eyes deteriorate, and so, someone who needed reading glasses at 40 is likely to need a stronger prescription for them at 50 -- whether they've actually been using glasses or not.
"Everybody does need stronger and stronger reading glasses -- it's inescapable," said Rosen.
In this case, the out-of-focus world that develops over time is due to the growing of the lens of the eye -- the only part of the eye that continues to grow significantly, and a process that prevents the eye from accommodating as easily as it did when one was younger.