One of the best things you can do for your eyes is to have them checked by your doctor whenever you have a physical examination. If you're having trouble seeing or you've been getting frequent headaches at the end of the day, have your eyes examined by an eye specialist.

It's a good idea to have your eyes checked at least every 2 years or even more frequently if you have a family history of eye problems such as glaucoma or early cataracts.

Myopia, or nearsightedness, is one of the most common problems. When a person has myopia, he or she is unable to focus properly on things that are far away. Their eyes are a little longer than normal, measuring from the front of the eyeball to the back. This extra length means that light focuses in front of the retina (the part of the eye that receives images and sends them to the brain) instead of on it, and that affects vision. Glasses or contacts can easily correct this problem.

Hyperopia, or farsightedness, is another problem. People with hyperopia have trouble focusing on things close up because their eyes are too "short" from front to back. In people with hyperopia, light focuses behind the retina instead of on it, causing blurry vision. Someone with significant farsightedness will need glasses to correct his or her vision.

Another condition where the eye is differently shaped is astigmatism. Here, the eye is slanted at the front, shaped more like a football than a baseball. To be able to see well, either close up or far away, contact lenses or glasses are required.