Amblyopia (Lazy Eye)

Lazy eye, or amblyopia, is the loss or lack of development of central vision in one eye that is unrelated to any eye health problem and is not correctable with lenses. It can result from a failure to use both eyes together. Lazy eye is often associated with crossed-eyes or a large difference in the degree of nearsightedness or farsightedness between the two eyes. It usually develops before the age of 6, and it does not affect side vision.

Symptoms may include noticeably favoring one eye or a tendency to bump into objects on one side. Symptoms are not always obvious.

Treatment for lazy eye may include a combination of prescription lenses, prisms, vision therapy and eye patching. Vision therapy teaches the two eyes how to work together, which helps prevent lazy eye from reoccurring.

Early diagnosis increases the chance for a complete recovery. This is one reason why the American Optometric Association recommends that children have a comprehensive optometric examination by the age of 6 months and again at age 3. Lazy eye will not go away on its own. If not diagnosed until the pre-teen, teen or adult years, treatment takes longer and is often less effective.

What is amblyopia?
Amblyopia (lazy eye) is the loss or lack of development of vision in an eye that is unrelated to any eye health problem. The brain, for some reason, does not acknowledge the images seen by the amblyopic eye. Reduced vision due to amblyopia is not correctable with lenses alone.

Who is likely to develop amblyopia?
Amblyopia is generally the result of poor early visual development, and as such, usually occurs before the age of eight. Infants born prematurely or with low birth weight are at a greater risk for the development of the condition.

It is estimated that two to four percent of children have amblyopia. The chance of amblyopia developing during adulthood is very small.

What causes amblyopia?
Amblyopia usually results from a failure to use both eyes together. It can be caused by the presence of strabismus (crossed-eyes), unequal refractive error (farsightedness or nearsightedness), or a physical obstruction of vision (cataract).

If there is a large enough difference in the degree of nearsightedness, farsightedness or astigmatism between the two eyes, or if the eyes are crossed, the brain learns to ignore one image in favor of the other.

How does amblyopia affect vision?
Normally, the images sent by each eye to the brain are identical. When they differ too much, the brain learns to ignore the poor image sent by one eye and “sees” only with the good eye.

The vision of the eye that is ignored becomes weaker from disuse.

Is the amblyopic eye blind?
The amblyopic eye is never blind in the sense of being entirely without sight.

Amblyopia affects only the central vision of the affected eye. Peripheral awareness will remain the same.

What are the signs/symptoms of amblyopia?
Amblyopia usually produces few symptoms. It may be accompanied by crossed-eyes or a large difference in the refractive error between the two eyes. A child may also exhibit noticeable favoring of one eye and may have a tendency to bump into objects on one side.

How is amblyopia diagnosed?
A comprehensive optometric examination can determine the presence of amblyopia. The earlier it is diagnosed, the greater the chance for a successful treatment.

Since amblyopia occurs only in one eye, the good eye takes over and the individual is generally unaware of the condition. That is why it is important to have your child’s vision examined at about six months, at age three and again before he or she enters school.

How is amblyopia treated?
Corrective lenses, prisms and/or contact lenses are often used to treat amblyopia.

Covering or occluding the better eye, either part-time or full-time, may be used to stimulate vision in the amblyopic eye. In addition, a program of vision therapy may be prescribed to help improve vision function.

Does amblyopia get worse?
Vision in the amblyopic eye may continue to decrease if left untreated. The brain simply pays less and less attention to the images sent by the amblyopic eye. Eventually, the condition stabilizes and the eye becomes virtually unused. It is quite difficult to effectively treat amblyopia at this point.

Is amblyopia preventable?
Early detection and treatment of amblyopia and significantly unequal refractive errors can help to reduce the chances of one eye becoming amblyopic.

How great a handicap is amblyopia?
Amblyopia is a handicap because it can limit the occupational and leisure activities you can do. Activities requiring good depth perception may be difficult or impossible to perform. In addition, should your good eye become injured or develop vision problems, you may have difficulty maintaining your normal activities.

Content reprinted from The American Optometric Association’s website,

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