Amblyopia or Lazy Eye

Overview

Amblyopia, also called "lazy eye", refers to reduced vision in one or both eyes caused by visual deprivation in childhood. It affects approximately 2% of all children. When an eye is inadequately stimulated during the first several years of life, that portion of the brain, which receives information from that eye, may not develop properly. Even with eyeglasses, an eye with amblyopia does not see well. Amblyopia may occur in various degrees depending on the severity of the underlying problem. Some patients just experience a partial loss; others a very significant loss. If discovered in the first several years of life, amblyopia is often reversible with the appropriate treatment.

Causes of Amblyopia

The causes of amblyopia are varied and include:

• Strabismus ("crossed eyes")- This refers to any misalignment of the eyes. When the eyes are not aligned, the child's brain will often select one eye with which to view the world while the other eye is "shut off" or "suppressed". The eye that is habitually crossed/suppressed is at risk for developing amblyopia.

• Anisometropia- This refers to an unequal prescription between the eyes. If eyeglasses are not worn, then the eye that receives the more blurred images (the eye with the stronger prescription) is at risk for developing amblyopia.

• Visual deprivation- Any ocular disease that blocks the visual images from reaching the retina can cause amblyopia. Examples include congenital cataracts, corneal opacities or droopy eyelids (ptosis).

Signs and Symptoms

Unless an obvious abnormality is present (such as crossing of the eyes or a dense cataract), amblyopia may have no apparent signs. Children rarely complain of poor vision, particularly if only one eye is affected. It is for this reason that parents should be very observant of young children, and why children need to undergo a vision screening periodically at their pediatrician's office.

Treatment

The key to successful treatment of amblyopia is early detection. If the amblyopia is caused by strabismus, patching therapy is generally recommended, and eye muscle surgery may be required. If anisometropic amblyopia is present, the proper eyeglasses are prescribed, possibly in conjunction with patching therapy. If there is a cataract or other ocular anomaly present, the appropriate surgery is recommended.

Patching therapy involves wearing an eye patch over the "stronger" or "good" eye. This will force the brain to use the eye with amblyopia. After wearing the patch for the prescribed duration of time, the amblyopia will often improve.

For achieving the best results, total visual deprivation of the good eye is recommended. Eye patches that adhere to the skin around the eye socket are most effective. Sometimes, particularly if a child is resistant to patching therapy, atropine eye drops may be of benefit. The atropine is instilled in the good eye, causing a blurring of vision, which may force the child to use the eye with amblyopia. It is not uncommon that children will refuse to wear the patch and/or remove it when left unsupervised. Patching should commence during a time when the parents can devote all their attention to the child, such as on a weekend. Typically, the first few days are the most difficult. Keeping the child occupied with games or television often helps. Occasionally, elbow splints or the use of socks over hands taped at the wrists may be required in the very young child who constantly removes the patch.

The ophthalmologist will prescribe the appropriate number of hours that the patch should be worn each day. While undergoing patching therapy, it is critical that the child return for a vision check at the recommended time intervals. This is to safeguard against the development of amblyopia in the eye being patched.

Generally, the younger the child, the quicker the desired results are obtained with amblyopia therapy. After about age eight or nine, the benefit of patching is questionable.