Amblyopia occurs when the nerve pathway from one eye to the brain does not develop during childhood. This problem develops because the abnormal eye sends the wrong image to the brain. This is the case in strabismus (crossed eyes). In other eye problems, a blurred image is sent to the brain. This confuses the brain, and the brain may learn to ignore the image from the weaker eye.

Strabismus is the most common cause of amblyopia. Having a family member with strabismus, increases your chance of having strabismus.

The term "lazy eye" refers to amblyopia, which often occurs along with strabismus. However, amblyopia can occur due to something other than strabismus. Also, people can have strabismus without amblyopia.

Other causes include:

• Childhood cataracts
• Farsightedness, nearsightedness, or astigmatism, especially if it is greater in one eye

In strabismus, the only problem with the eye itself is that it is pointed in the wrong direction. If poor vision is caused by a problem with the eyeball, such as cataracts, amblyopia will still need to be treated, even if the cataracts are removed. Amblyopia may not develop if both eyes have equally poor vision.

Symptoms of the condition include:

• Eyes that turn in or out
• Eyes that do not appear to work together
• Inability to judge depth correctly
• Poor vision in one eye

In most cases, amblyopia can be detected with a complete eye exam. Special tests are not often needed.

The first step will be to correct any eye condition that is causing poor vision in the amblyopic eye (such as cataracts).

Children with a refractive error (nearsightedness, farsightedness, or astigmatism) will need glasses.

Next, a patch is placed on the normal eye. This forces the brain to recognize the image from the eye with amblyopia. Sometimes, drops are used to blur the vision of the normal eye instead of putting a patch on it.

Newer treatment techniques use digital computer technology, to show a slightly different image to each eye. Over time, the vision between the eyes becomes equalized.

Children whose vision will not fully recover, and those with only one good eye due to any disorder should wear glasses. These glasses should be shatter- and scratch-resistant.

Children who get treated before age 5 almost always recover vision that is close to normal. However, they may continue to have problems with depth perception.

Permanent vision problems may result if treatment is delayed. Children treated after age 10 can expect vision to recover only partially.

Complications may include:

• Eye muscle problems that may require several surgeries
• Permanent vision loss in the affected eye

Contact your health care provider or ophthalmologist if you suspect a vision problem in a young child.

Identifying and treating the problem early prevents children from having permanent visual loss. All children should have a complete eye exam at least once between ages 3 and 5.

Special methods are used to measure vision in a child who is too young to speak. Most eye care professionals can perform these techniques.

Lazy eye; Vision loss - amblyopia

Ellis GS, Pritchard C. Amblyopia. In: Yanoff M, Duker JS, eds. Ophthalmology. 5th ed. Philadelphia, PA: Elsevier; 2019:chap 11.11.

Kraus CL, Culican SM. New advances in amblyopia therapy I: binocular therapies and pharmacologic augmentation. B J Ophthalmol. 2018;102(11):1492-1496. PMID: 29777043 pubmed.ncbi.nlm.nih.gov/29777043/.

Olitsky SE, Marsh JD. Disorders of vision. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 639.

Repka MX. Amblyopia: the basics, the questions, and the practical management. In: Lyons CJ, Lambert SR eds. Taylor and Hoyt's Pediatric Ophthalmology and Strabismus. 6th ed. Philadelphia, PA: Elsevier; 2023:chap 74.

Xiao S, Angjeli E, Wu HC, et al. Randomized controlled trial of a dichoptic digital therapeutic for amblyopia. Ophthalmology. 2022;129(5):593. PMID: 34534556 pubmed.ncbi.nlm.nih.gov/34534556/.

Yen M-Y. Therapy for amblyopia: a newer perspective. Taiwan J Ophthalmol. 2017;7(2):59-61. PMID: 29018758 pubmed.ncbi.nlm.nih.gov/29018758/.

Updated by: Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision Institute, La Jolla, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.