Amblyopia (Lazy Eye)
A most common vision disorder in children is amblyopia, or "lazy eye." This common is very common, and it is responsible for more vision loss in children than all other cases combined. Amblyopia is defined as a reduction in visual acuity without any structural abnormality of the eye resulting from abnormal visual input early in life.
Only children can develop amblyopia, and without treatment, it can cause a lifetime of uncorrectable visual loss. Unlike children with eye problems that can be corrected with glasses, children with amblyopia have visual loss which does not usually improve, even with the best of glasses.
Strabismic amblyopia occurs when the eyes are crossed, turned out, or otherwise misaligned. In this condition, the eye which is misaligned is "turned off" by the brain. Deprivation amblyopia occurs in young children whose eyes are "deprived" of visual experience by cataracts or similar conditions. Without very early treatment, these children can have extremely poor vision.
Anisometropic amblyopia occurs when one eye is out of focus. Parents and pediatricians may not suspect the disorder because the eyes may remain perfectly straight and the good eye sees normally. Therefore, children with this type of amblyopia typically remain undiscovered and treatment is delayed until they have had a vision screening test. This is best done by the primary care physician between ages 3 and 4 and, if done carefully, will detect a difference in visual acuity between the two eyes. Prompt diagnosis and referral can lead to a reduction of the amblyopia in almost all cases.
In most cases, amblyopia affects only one eye. One exception is bilateral refractive amblyopia. In this condition, an uncorrectable vision loss in both eyes results from severe farsightedness, nearsightedness, or astigmatism in both eyes, which is not corrected early.
Early treatment for amlyopia is always best. Children with refractive errors can be fit with corrective glasses or contact lenses as early as the first week of life, if necessary. In most cases, patching of the normal eye is used to strengthen the amblyopic eye. Patching should be prescribed by an ophthalmologist, and its effect must be monitored at regular intervals. Although it can be difficult, patching is usually effective if begun early enough and complied with appropriately by both the parent and the child. Sometimes "penalizing" the good eye by blurring it with drops or with extra power in the glasses can be used as an alternative to patching, especially in mild forms of amblyopia and in school age children who will not cooperate with patching therapy.
In cases with congenital cataracts, surgery can remove the cataracts. Following this, optical correction and patching are usually necessary. Surgery on the eye muscles align the eyes but this in itself is not an effective treatment of amblyopia. It can only help make the eyes work together as a team.
In all cases, the goal is the best possible vision in each eye. Patching is generally not as effective after age 9. Patching of older individuals is seldom worthwhile. Some cases of amblyopia can be resistant to therapy. The decision to stop treatment can be difficult but is sometimes best for both the child and the family. Children with useful vision in only one eye are prescribed safety glasses and sports goggles to protect the normal eye. As long as the eye remain healthy, such children see normally in almost every respect.