Amblyopia (Lazy Eye)

By December 16, 2014 Eye Diseases One Comment

Amblyopia (Lazy Eye)Amblyopia — also called “lazy eye” — is poor vision in an eye due to the lack of normal visual development despite the eye being healthy. If left untreated, amblyopia can result in permanently depressed visual acuity in the affected eye.

Amblyopia occurs during early childhood, and it’s estimated that about 2 to 3 percent of the U.S. population has some degree of amblyopia.

Amblyopia Signs and Symptoms

Since amblyopia typically affects only one eye, lazy eye often can be difficult to detect without a comprehensive eye exam. When both eyes are open, the child simply compensates for the blurry amblyopic eye by relying on the unaffected “good” eye.

The American Optometric Association recommends that all children have their first eye exam at 6 months of age, another exam at age 3 and a third exam prior to entering school to ensure vision is developing normally in both eyes and there is no risk of amblyopia.

A simple screening test you can try at home is to cover and uncover your child’s eyes (one eye at a time) when he or she is performing a visual task, such as watching television. If the child is not bothered when one eye is covered, but objects when the other eye is, it’s possible amblyopia is present in the first eye.

In other words, children with amblyopia don’t mind when their blurry (amblyopic) eye is covered, since they are used to relying on their unaffected “good” eye. When the good eye is covered and they have to rely solely on the blurry amblyopic eye, this is bothersome.

But a simple screening test is no substitute for a comprehensive eye exam. Have your child’s eyes examined as recommended to make sure he or she has normal vision in both eyes and that the eyes function together properly as a team.

What Causes Amblyopia?

Basically, there are three types of amblyopia, based on the underlying cause:

  1. Strabismic amblyopia. This is lazy eye caused by misalignment of the eyes (strabismus). To prevent double vision, the visual part of the brain ignores (suppresses) vision from the turned eye, resulting in incomplete visual development in that eye.
  2. Refractive amblyopia. This type of lazy eye is caused by a significant difference in the amount of refractive error (nearsightedness, farsightedness or astigmatism) in the two eyes. In such cases, the brain ignores the more blurred images from the eye with greater refractive error and favors the clearer images produced by the “good” eye that has less refractive error.
  3. Deprivation amblyopia. This is lazy eye caused by something that obstructs light from entering and being focused in a baby’s eye, such as a congenital cataract. Prompt treatment of congenital cataracts is necessary to allow normal visual development to occur.
    Strabismus is the most common cause of amblyopia.

Treatment of Amblyopia

The method of treatment for amblyopia depends on the cause. But generally speaking, the sooner any type of amblyopia is treated, the better the chances that the affected eye will develop normal (20/20) visual acuity.

Strabismic amblyopia

Successful treatment of strabismic amblyopia first requires the eyes to be properly aligned. In most cases, this means surgery.

Once the eyes are surgically straightened, part-time patching of the “good” eye usually helps improve visual acuity in the amblyopic eye. A program of vision therapy — a prescribed set of specific visual activities that may or may not require optical aids — often is recommended after strabismus surgery to help the two eyes learn to work together as a team to produce clear, comfortable binocular vision and normal depth perception.

The first step in correcting refractive amblyopia is to fully correct the refractive error in both eyes. Because eyeglass lenses can cause unwanted and unequal magnification of images when the refractive error is significantly different in the two eyes, contact lenses (which cause little or no unwanted image magnification) often are a better solution than glasses.

Following full correction of refractive errors, patching the good eye usually will help stimulate improvement of visual acuity in the amblyopic eye. Your eye doctor might also recommend a program of vision therapy to make sure the two eyes work together properly as a team.

Refractive amblyopia

The first step in correcting refractive amblyopia is to fully correct the refractive error in both eyes. Because eyeglass lenses can cause unwanted and unequal magnification of images when the refractive error is significantly different in the two eyes, contact lenses (which cause little or no unwanted image magnification) often are a better solution than glasses.

Following full correction of refractive errors, patching the good eye usually will help stimulate improvement of visual acuity in the amblyopic eye. Your eye doctor might also recommend a program of vision therapy to make sure the two eyes work together properly as a team.

Deprivation strabismus

When congenital cataracts occur, surgery to remove the cataracts should be performed as soon as possible to prevent permanent vision loss from deprivation amblyopia. A pediatric ophthalmologist who specializes in cataract surgery for infants and small children should be consulted.

Following surgery, contact lenses, eyeglasses, patching and vision therapy may be needed to fully correct the refractive error in both eyes and improve visual acuity and eye teaming.

amblyopia2Alternatives to Eye Patching

Most kids dislike having their good eye patched during amblyopia treatment — not only because it makes their vision blurry until visual acuity in the amblyopic eye improves, but because an eye patch draws unwanted attention to their condition.

If your child refuses to wear an eye patch or it appears that doing so is traumatic, other (though more expensive) options exist. Your eye doctor can prescribe an “occluder” contact lens to be worn on the good eye instead of an eye patch. This type of specialty contact lens has an opaque tint in the center of the lens that blocks light from entering the pupil, thereby producing the same effect as an eye patch without noticeably affecting the wearer’s appearance.

Special eye drops that temporarily cause blurring of the good eye are another alternative to patching. Your eye doctor can discuss this option with you in greater detail if an alternative to eye patching or wearing an occluder contact lens wear is desired.

Take Action As Soon As Possible

Amblyopia will not go away on its own, and untreated amblyopia can lead to permanently blurred vision in the affected eye and poor depth perception. Also, if your child has significant amblyopia and sustains an injury or serious infection in his or her “good” eye that causes vision loss in that eye, this could result in a permanent visual disability or even legal blindness.

To prevent this and to give your child the best vision possible, amblyopia should be treated early on. If amblyopia is promptly detected and treated before age 8 or 9, in most cases the affected eye will be able to successfully attain 20/20 vision.

If amblyopia persists after treatment, protective eyewear should be worn at all times to safeguard the health and visual acuity of the “good” eye.

Article ©2013, Access Media Group LLC. Source: Amblyopia (Lazy Eye) by AllAboutVision.com.

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