What Is Lazy Eye?
Amblyopia is poor vision in an eye that did not develop normal sight during early childhood. It is sometimes called “lazy eye.”
When one eye develops good vision while the other does not, the eye with the poorer vision is called amblyopic. Usually, only one eye is affected by amblyopia, but it is possible for both eyes to be “lazy” if there is a large uncorrected glasses prescription. This condition is called refractive amblyopia.
Amblyopia is common; approximately two or three out of every 100 people has amblyopia. The best time to correct amblyopia is during infancy or early childhood. It is difficult to achieve much improvement in vision after age 7.
Newborn infants are able to see, but as they use their eyes during the first months of life, their vision improves. During early childhood years, their visual system changes quickly and their sight continues to develop.
In order to have normal vision, it is important that both eyes develop equal vision. If a child has amblyopia and cannot use his or her eyes normally, vision does not develop properly and may even decrease. After the first nine years of life, the visual system is normally fully developed and usually cannot be changed.
If amblyopia treatment is not begun as early as possible, several problems can develop that can seriously affect vision from childhood into adulthood:
- the amblyopic eye may develop a serious and permanent visual defect
- depth perception (seeing in three dimensions) may be lost, because good vision in both eyes is needed
- if the stronger eye becomes diseased or injured, it can mean a lifetime of poor vision
It is not easy to recognize amblyopia (lazy eye) in children. A child may not be aware of having one stronger eye and one weaker eye. Unless the child has an eye that is misaligned or another condition that can be seen, there is often no way for parents to tell that something is wrong.
Some symptoms of amblyopia (lazy eye) to look for in a child include:
- Poor vision in one eye or overall poor vision
- Squinting, tilting the head or closing one eye to see
- Poor depth perception (difficulty judging relative distances between objects)
- An inward- or outward-wandering eye
The following factors can raise a child’s risk of having amblyopia (lazy eye):
- Having misaligned eyes (strabismus)
- Severe nearsightedness or farsightedness in both eyes
- Unequal vision in both eyes (one eye more nearsighted or farsighted than the other)
- Having a condition that prevents light from entering the eye correctly, such as cataract or possibly a droopy eyelid
- Family history of amblyopia or strabismus
- Premature birth or low birth weight
Detecting strabismus and amblyopia in children
All children, whether or not they are at risk for amblyopia (lazy eye), should have their eyes examined. Detecting and treating amblyopia as early as possible will make a real difference later on in their lives. In addition to the well-baby exams that all babies should have as newborns and between ages 6 to 12 months, preschool-aged children should have an eye examination between the ages of 3 and 4 years old.
It is not easy to recognize amblyopia. A child may not be aware of having one strong eye and one weak eye. Unless the child has a misaligned eye or other obvious abnormality, there is often no way for parents to tell that something is wrong. Poor vision in one eye does not always mean that a child has amblyopia. Vision can often be improved by prescribing eyeglasses for a child.
Amblyopia is the result of the eyes not working together. This may be caused by a constant misalignment of the eyes (strabismic amblyopia) or a significant difference in the child’s eyeglass prescription between the two eyes (refractive amblyopia).
With amblyopia (lazy eye) treatment, a child’s stronger eye is covered with a patch so that the weak eye is used instead. Through continued use, the weaker eye becomes stronger, allowing vision to develop normally.
If refractive amblyopia is a problem, eyeglasses may be prescribed first to correct the focusing errors. If glasses alone do not improve a child’s vision, then patching is needed — usually for several months. Covering the child’s stronger eye with a patch forces the child to use their weak eye. Another way to accomplish this technique is to blur the vision in the strong eye with special eyedrops or a pair of glasses with a blurry lens over the stronger eye.
Lazy eye correction or treatment should begin as soon as possible so that the child’s visual system can develop properly. Even after vision has been restored in the weaker eye, it may be necessary to continue patching the lazy eye part-time for a few more years to maintain the improvement.
In the case of amblyopia associated with strabismus (misaligned eyes), surgery is usually required to insure a good outcome. Amblyopia is usually treated before surgery with patching. Then surgery is performed to correct misaligned or crossed eyes. Patching or blurring with eyedrops is often continued after surgery as well.
If a cataract or other problem in the eye that is causing the visual problem, surgery may be required to correct the problem that is causing amblyopia.
Amblyopia usually cannot be cured by treating the cause alone. The weaker eye must be made stronger in order to see normally. Prescribing eyeglasses or performing surgery can correct the cause of amblyopia. Patching and therapy will be required as well to strengthen the weaker eye.