The eye works very much like a camera. The front part of the eye—the cornea and lens—focus light onto the back of the eye, or retina. Once the retina receives a picture, it sends a signal to the brain, via the optic nerve, for the picture to be developed. The most common vision problems are those where the shape of your eye does not bend the light coming into the eye properly. This makes the picture that is sent to the brain look blurry.
The most common problems include:
Nearsightedness means that you see close objects clearly, but distant objects are blurry. This happens when the eyeball is too long or when the outer layer of the eye, called the cornea, is too curved. This causes light rays to focus at a point in front of the light-sensitive tissue at the back of the eye (retina) instead of directly on it.
A sign of nearsightedness may be squinting to see road signs clearly. A nearsighted child may not be able to read the chalkboard at school or to watch TV without sitting very close. Nearsightedness may be helped with glasses, contacts, or eye surgery.
Farsightedness is when you see distant objects clearly, but close objects are blurry. This happens when the eyeball is too short or when the outer layer of the eye, called the cornea is too flat. This causes light rays to focus behind the light-sensitive tissue at the back of the eye called the retina instead of directly on it.
Some signs of farsightedness include blurry vision when looking at objects up close. You may also notice eyestrain, fatigue, aching or burning eyes, and headaches after doing close work (such as reading or needlework). Often babies are born with a slight farsightedness that clears up as they grow and their eyeballs get longer. Children with farsightedness may not be interested in reading or they may have trouble concentrating because they cannot keep close objects in focus. Farsightedness may be helped with glasses, contacts, or refractive surgery.
Presbyopia is the loss of clear close-up vision that happens naturally as people get older. Around the age of 40, the lenses of your eyes start to lose elasticity and flexibility. With less elasticity, the eye may be unable to focus sharply on close objects.
Some signs of presbyopia include blurred vision at normal reading distance and the tendency to hold things at arm's length to read them. You may also have eye fatigue and headaches when doing close work. Contacts are sometimes used for presbyopia. However, it may be easier for people who already wear contacts to get reading glasses that magnify close-up objects.
Astigmatism is distorted vision caused by an unevenly curved cornea. The cornea is the clear outer layer on the front of the eye. As a result of astigmatism, your vision is somewhat blurry all the time. Astigmatism is usually present at birth.
Mild astigmatism may cause headaches, eyestrain, fatigue, or blurred vision. Severe astigmatism is corrected with glasses or contacts. Astigmatism may also be treated with refractive surgery.
See your eye care provider if you are concerned about your vision. If you don’t have symptoms, the American Academy of Ophthalmology recommends eye exams according to the following schedule:
You may need to see your eye care provider more often if you have certain eye problems, diseases, or risk factors. For example, if glaucoma or diabetes run in your family. Have your eyes checked regularly even if you do not have eye symptoms.
