Amblyopia (Lazy Eye)
What is amblyopia?
Amblyopia, commonly known as “lazy eye”, is a condition in which the vision in one or both eyes cannot be corrected even after corrective eyeglasses have been prescribed. In a child with normal visual development, the brain receives information from the right eye and information from the left eye and combines the two to see one clear picture of the world. This is called fusion.
Amblyopia occurs when the brain is unable to fuse information. As a result the brain suppresses the information from the weaker eye, which leads to further deterioration. Amblyopia can be caused by an unequal alignment of the eyes, an uneven prescription in the two eyes, or by an organic obstruction to the eye.
Generally, amblyopia will develop within the first few years of life. Fortunately, however, amblyopia can be treated at any age.
What types of amblyopia can occur?
Three most common types are:
Anisometropic Amblyopia (due to a difference in optical power in the two eyes):
This is a condition in which the optical correction is very diverse between the two eyes. For example, one eye may be very farsighted while the other is only slightly farsighted, causing the brain to ignore the eye with the blurry images.
Isometropic Amblyopia (due to a high degree of optical correction in both eyes):
This condition is when the optical correction is very high in both eyes. Because the child has not worn glasses, the vision in both eyes will be poor.
Strabismic Amblyopia (due to misalignment of the two eyes):
This is a condition in which one eye is turned in or out. This eye is ignored by the brain, leading to more deterioration of vision in that eye.
How common is amblyopia?
Approximately three percent of children and young adults have amblyopia.
What are the problems and symptoms associated with amblyopia?
The main problem associated with amblyopia is poor vision in one or both eyes. The child usually does not complain because the vision in the good eye is unaffected. If the amblyopia is a result of poor optics in one eye, the eyes appear very normal and crossed eyes or other obvious problems are not present. Only a vision screening or professional eye examination can detect this problem. This is one reason we recommend the first professional eye examination at six months of age.
How is amblyopia treated?
If the problem is due to the optics of the eyes, eyeglasses will be prescribed and, in most cases, need to be worn full-time. In addition, the good eye may need to be patched to force the weaker one to be used. Vision therapy is necessary to improve binocular vision (both eyes working simultaneously). The amount of patching required varies from case to case. Generally, the process takes about six months with the most dramatic improvement occurring in the first three months of patching and therapy.
If the basis for the amblyopia is an eye turn, glasses may or may not be necessary but patching and vision therapy are essential. In some cases, a surgical consultation is advised. Follow-up visits are important in order to determine the progress of treatment.
Vision therapy, a successful treatment approach to remedy amblyopia, involves weekly office visits. During treatment, the patient is assigned select activities designed to restore normal flexibility to the eyes. This should lead to improved visual acuity.
View our Optometry and Vision Therapy sections for more information on common vision problems in children. Also find out more about the optometrists and vision specialists at Ezra Medical Center.