Amblyopia caused by cataracts (cloudiness in the eye tissues) is less common, but more severe. It must be treated in the first 2 months of life. Amblyopia normally only affects one eye, but it is possible to be amblyopic in both eyes if both are similarly deprived of a good, clear visual image. Amblyopia, commonly known as "lazy eye ", is a visual disorder affecting as many as 2 or 3 percent of children under the age of six.

Children with amblyopia experience significant vision loss in one eye, causing a loss of stereoscopic vision and possible blindness in the affected eye.

Amblyopia must be treated as soon as possible if vision is to be restored. The results of treatment depend on the duration and severity of amblyopia and the age treatment is begun. Amblyopia can be successfully treated up to the age of 17. Early treatment is usually simple, employing glasses, drops, vision therapy and/or patching. Amblyopia is sometimes treated before or at the same time as surgery to correct misaligned eyes, remove a cataract, or correct another ocular abnormality. In some cases, cataract surgery or glaucoma surgery might be necessary to treat deprivation amblyopia.

Amblyopia is an important socioeconomic problem. Studies have shown that it is the number one cause of monocular vision loss in adults. Amblyopia is diagnosed with an eye exam. If the exam shows that a child has poor vision in one eye, the doctor may diagnose amblyopia after ruling out other causes. Amblyopia may be caused by any condition that affects normal visual development or use of the eyes. Amblyopia can be caused by strabismus or "crossed eye," an imbalance in the positioning of the two eyes.

Amblyopia can result from a constant unilateral strabismus (i.e., either the right or left eye turns all of the time). Alternating or intermittent strabismus (an eye turn which occurs only some of the time) rarely causes amblyopia . Amblyopia can be caused by strabismus, an imbalance in the positioning of the two eyes. Strabismus can cause the eyes to cross in (esotropia) or turn out (exotropia). Amblyopia, which usually begins in infancy or childhood, is a condition of poor vision in an otherwise healthy eye because the brain has learned to favor the other eye. Although the eye with amblyopia often looks normal, there is interference with normal visual processing that limits the development of a portion of the brain responsible for vision.

Amblyopia normally only affects one eye, but it is possible to be amblyopic in both eyes if both are similarly deprived of a good, clear visual image. Detecting the condition in early childhood increases the chance of successful treatment. Amblyopia specifically refers to abnormal best-corrected vision in an eye. Thus, if vision is measured to be poor in an eye because of myopia, and that eye can see 20/20 once glasses are prescribed, then amblyopia does not exist. Amblyopia usually develops in children before age eight. This is also the key time to treat amblyopia, since results are better the earlier they are implemented.

Amblyopia refers to reduced vision in one or both eyes caused by visual deprivation in childhood. That is, even with proper eyeglasses, an eye with amblyopia does not see well!