Reading in poor light will hurt the eyes: Before the invention of electric light, most nighttime reading and other work was done by dim candlelight or gaslight. Reading in dim light today won't harm our eyes any more than it did our ancestors' eyes or any more than taking a photograph in dim light will damage a camera.
Holding a book too close or sitting too close to the television set is harmful to the eyes: Many children with excellent vision like to hold books very near to their eyes or site close to the television set. Their youthful eyes focus very well up close, so this behavior is natural to them, and it is safe. Children and adults who are nearsighted might need to get close to a book or television set to see clearly. Doing so does not cause or worsen nearsightedness or any other kinds of eye problem.
Using the eyes too much and "wear them out": We wouldn't lose our sense of smell by using our nose too much or our hearing by using our ears too much. The eyes were made for seeing. We won't lose our vision by using our eyes for their intended purpose.
Wearing eyeglasses that are too strong or have the wrong prescription will damage the eyes: Eyeglasses change the light rays that the eye receives. They do not change any part of the eye itself. Wearing glasses that are too strong or otherwise wrong for the eyes cannot harm an adult's, although it might result in a temporary headache. At worse, the glasses will fail to correct vision and make the wearer uncomfortable because of blurriness, but no damage to any part of the eye will result.
Wearing eyeglasses will weaken the eyes: The eyeglasses worn to correct nearsightedness, farsightedness, astigmatism, or presbyopia will not weaken the eyes any more than they will permanently "cure" these kinds of vision problems. Glasses are simply external optical aids that provide vision to people with blurred vision caused by refractive errors. Exceptions are the kinds of glasses given to children with crossed eyes (strabismus) or lazy eye (amblyopia). These glasses are used temporarily to help straighten the eyes or improve vision. Not wearing such glasses may lead to permanently defective vision.
Crossing the eyes can make them permanently crossed: Our eye muscles are meant to allow us to move our eyes in many different directions. Looking left, right, up, or down, will not force the eyes to stay permanently crossed. Crossed eyes result from disease, from uncorrected refractive error, or from muscle or nerve damage, not from forcing the eyes into that position.
Having 20/20 vision means that the eyes are perfect: The term "20/20" denotes a person with excellent central vision. But other types of vision-such as side vision, night vision, or color vision might be imperfect. Some potentially blinding eye disease, such as glaucoma or diabetic retinopathy, can take years to develop. During this time, they are harming parts of the inner eye, but the central vision can remain unaffected.
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