What are the other Names for this Condition? (Also known as/Synonyms)

• AA (Anisometropic Amblyopia)

What is Anisometropic Amblyopia? (Definition/Background Information)

• Amblyopia, also known as lazy eye, is a condition that results in decreased vision in an eye that typically appears normal. The most common cause of amblyopia is strabismus, an eye disorder causing misaligned eyes
• Anisometropic Amblyopia (AA) refers to unilateral amblyopia caused by a distinct refractive error of each eye (i.e., the refractive power in each eye varies). Anisometropia is the second most common cause of amblyopia. It forms a part of refractive amblyopia that may be caused by nearsightedness, farsightedness, or astigmatism
• The condition, predominantly seen in young children, is usually diagnosed during wellness (physical) exams, annual visits to a pediatrician, or through vision screening exams conducted in elementary schools

Who gets Anisometropic Amblyopia? (Age and Sex Distribution)

• It is reported that between 35-50% of amblyopia cases are Anisometropic Amblyopia
• According to a worldwide study, the global prevalence rate of amblyopia is around 1.5%. The prevalence rates are lower in Asia and Africa when compared to North America and Europe (prevalence rates of 0.72-1.09% versus 2.41-2.90%)
• Most cases of amblyopia are first diagnosed in children under the age of 8 years. In rare cases, a late-onset of amblyopia can occur in adults
• Males and females are equally affected, and no gender preference is observed

What are the Risk Factors for Anisometropic Amblyopia? (Predisposing Factors)

Anisometropic Amblyopia is a common form of amblyopia. The common risk factors of amblyopia include:

• Family history of amblyopia
• Premature birth and/or low birth weight
• Refractive errors of the eye

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Anisometropic Amblyopia? (Etiology)

• Anisometropic Amblyopia is a form of refractive amblyopia that results from vision differences between the eyes caused by conditions such as nearsightedness (myopia), farsightedness (hyperopia), and astigmatism
• The greater the difference in refractive power of the two eyes, the greater is the severity of Anisometropic Amblyopia
• Some researchers believe that the difference in refractive power of the two eyes may be due to abnormal visual pathways from the brain to the eye

What are the Signs and Symptoms of Anisometropic Amblyopia?

In Anisometropic Amblyopia, the eyes typically appear normal. The signs and symptoms are often slow to occur. In general, the signs and symptoms of amblyopia include:

• Depth perception problems
• Crossed eyes
• Eyes turned out
• Blurry vision in one or both eyes
• Eye coordination difficulties
• Headaches
• Squinting
• Other vision signs and symptoms such as lack of binocular vision

How is Anisometropic Amblyopia Diagnosed?

A diagnosis of Anisometropic Amblyopia may involve the following test and exams:

• Physical examination and medical history evaluation
• Assessment of signs and symptoms: The healthcare provider will look for symptoms including wandering eyes, eye turn, vision differences between the eyes, and refractive errors
• General eye exam
• Neuronal receptive fields
• Corneal light reflex test
• Contrast sensitivity
• Grating acuity
• Visual acuity test using a special and standardized test chart (Snellen chart)
• Refraction studies using various instruments
• Fundoscopic (ophthalmoscopic) examination by an eye specialist, who examines the back part of the eye (or the fundus)
• Slit-lamp examination
• Imaging studies including CT and MRI scans of the head and neck region, if necessary

Tests and exams to determine an underlying cause, if present, may be necessary.

Many other clinical conditions may cause vision loss in children. Your optometrist or pediatric ophthalmologist may perform additional tests to rule out other conditions.

What are the possible Complications of Anisometropic Amblyopia?

If Anisometropic Amblyopia is left untreated, complete vision loss in the affected eye(s) is a significant complication. The other complications may include:

• Vision problems causing an inability to read, drive, play sports, or perform simple tasks
• Development of strabismus
• Decreased quality of life due to loss of stereoscopic vision; this can also increase one’s risk for vehicular or occupational accidents
• Treatment related complications

How is Anisometropic Amblyopia Treated?

Anisometropic Amblyopia may be treated successfully with early intervention and appropriate therapy. The main purpose of treatment is to eliminate the advantage of the dominant eye that is used for vision. By removing participation of the dominant eye, the lesser dominant eye participates more in vision processing resulting in a decrease in severity of signs and symptoms.

The treatment involves correcting the refractive error between the eyes. Often, an individualized treatment is planned and provided. The available treatment options include:

• Prescription glasses for full-time wear (usually the first-line of treatment)
• Use of full-time cycloplegic refraction eye wear
• Eye patching (for non-amblyopic eye) in certain cases
• Use of medications such as atropine
• Eye surgery may be needed for conditions such as cataracts or droopy eyelids

How can Anisometropic Amblyopia be Prevented?

Currently, there are no known prevention methods for Anisometropic Amblyopia. To prevent symptoms from getting worse, early recognition and treatment is important.

• Efforts can be taken to reduce one’s risk of developing amblyopia by having regular eye examinations, especially in infants and young children
• Periodic eye examinations for older children and adults, especially if there is a high risk for development of the condition
• Undertaking early and adequate treatment of refractive errors such as myopia, hyperopia, and astigmatism

What is the Prognosis of Anisometropic Amblyopia? (Outcomes/Resolutions)

The prognosis of Anisometropic Amblyopia depends on the severity of the condition, one’s age, and treatment response.

• The younger the children with the condition are corrected, the better are the outcomes (typically before age 10)
• Individuals with unilateral high myopia and combined myopia/astigmatism have worse prognosis
• If diagnosis and treatments are delayed, the vision may be permanently affected

Additional and Relevant Useful Information for Anisometropic Amblyopia:

Please visit our Eye & Vision Center for more physician-approved health information:

http://www.dovemed.com/health-topics/vision-center/