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Lazy Eye (Amblyopia and Strabismus)


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 problems. The brain 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 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. Amblyopia can also develop with an uncorrected eye turn, refractive error, or cataract. 

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

If there is a large enough difference in the degree of nearsigtedness, 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 very similar. 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 the 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 usually 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 six months of age, at age three and again before he or she enters school.

How is amblyopia treated?
Treatment that includes patching the good eye may help the amblyopic eye to improve. In addition, to help improve vision function, vision therapy techniques may be used. Eyeglasses or contact lenses may be prescribed to correct any refractive errors. A better outcome is achieved the earlier that amblyopia, or a condition that could lead to amblyopia, is diagnosed and treatment is initiated. Special eye drops can also be used under the guidance of our optometrists. 

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 concern is amblyopia?
Amblyopia is a challenge because it can limit the occupational and leisure activities one 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.


What is strabismus?
Strabismus, sometimes known as "crossed eyes," is a visual condition in which the eyes are not accurately aligned. One eye may be constantly or periodically turned in, out, up, or down in relation to the other eye. This lack of eye teaming may also occur under certain conditions such as when a person is tired or inattentive, or looks in a certain direction or at a specific distance. The eye turn may alternate between eyes.

What causes strabismus?
Strabismus is caused by a lack of nerve muscle coordination, neurological, or mechanical causes. Strabismus may also occur due to an eye injury, head injury, or stroke. It could also be caused by excessive farsightedness. Strabismus tends to be hereditary, but there are many factors involved.

Who is affected by strabismus?
Strabismus tends to occur either shortly after birth, around age three, or shortly after children start school. Some strabismus develops later in life due to a problem that has existed for many years, for which a person can no longer cocmpensate. Strabismus due to a stroke or injury can occur at any age. 

Will a child outgrow strabismus?
Children almost never outgrow strabismus. It usually becomes more habitual over time and is frequently the cause of amblyopia in which the vision in the deviated eye decreases due to lack of use. If left untreated, amblyopia may result in legal blindness of the affected eye.

What are the effects of strabismus?
Strabismus can initially cause double vision. To avoid double vision, the brain often disregards the image from one eye. This can result in permanent vision loss from amblyopia, and impairs the function of stereopsis (binocular depth perception), which can affect sports performance, driving, and many other activities of daily living.

How is strabismus diagnosed?
Strabismus can be easily missed. All children should have a comprehensive eye examination by our optometrists at age six months, at age three, and before starting school. The earlier that strabismus is diagnosed, the greater likelihood of successful treatment.

How is strabismus treated?
Treatment of strabismus may include glasses, vision therapy, patching, and surgery. The specific treatment depends on the condition, its cause, its severity, and the age of the patient. Strabismus can often be corrected with excellent results if detected and treated early.

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