Amblyopia

• David Robbins Tien, M.D.
• Alexandra Meyer Tien, M.D.

 Basic Information

Definition

Amblyopia refers to decreased vision in one or both eyes as a result of insufficient stimulation of the developing visual system. The most common etiologies of amblyopia are ocular misalignment (strabismus) and unequal refractive error (anisometropia). Less commonly, amblyopia results from bilateral high refractive error (ametropic) or blockage of the ocular media (deprivation).

Synonyms

1. Deprivation amblyopia (formerly amblyopia ex anopsia)

2. Occlusion amblyopia

3. Strabismic amblyopia

4. Refractive amblyopia

5. Lazy eye

ICD-10CM CODES
H53.009	Unspecified amblyopia, unspecified eye
H53.001	Unspecified amblyopia, right eye
H53.002	Unspecified amblyopia, left eye
H53.009	Unspecified amblyopia, unspecified eye
H53.019	Deprivation amblyopia, unspecified eye
H53.011	Deprivation amblyopia, right eye
H53.012	Deprivation amblyopia, left eye
H53.013	Deprivation amblyopia, bilateral
H53.029	Refractive amblyopia, unspecified eye
H53.021	Refractive amblyopia, right eye
H53.022	Refractive amblyopia, left eye
H53.023	Refractive amblyopia, bilateral
H53.039	Strabismic amblyopia, unspecified eye
H53.031	Strabismic amblyopia, right eye
H53.032	Strabismic amblyopia, left eye
H53.033	Strabismic amblyopia, bilateral

Epidemiology & Demographics

Incidence (In U.S.)

1% to 5% of the general population. Amblyopia is the leading cause of vision loss in children. It is also the cause of permanent vision loss in approximately 2.9% of adults.

Prevalence (In U.S.)

High incidence in premature infants with drug-dependent mothers and in neurologically impaired children. Children with a family history of strabismus, amblyopia, or high refractive errors are at increased risk.

Predominant Sex

None

Predominant Age

Childhood

Peak Incidence

Childhood

Physical Findings & Clinical Presentation

Decreased vision using best refraction in the presence of normal retinal and optic nerve appearance (Fig. E1).

Etiology

1. •

   Refractive errors

2. •

   Strabismus

3. •

   Visual deprivation from congenital cataract, corneal opacities, ptosis or nystagmus

4. •

   Occlusion from patching (rare)

5. •

   Malnutrition or vitamin deficiency

Diagnosis

Differential Diagnosis

1. •

   Central nervous system (CNS) disease (i.e., cortical visual impairment)

2. •

   Optic nerve disorders

3. •

   Corneal or other eye diseases

4. •

   Retinal disorders

5. •

   Malingering or secondary gain (i.e., desire for glasses in children—more commonly girls)

Workup

1. •

   Complete eye examination to find the cause of decreased vision. Referral to an ophthalmologist is recommended for any child with a visual acuity in either eye of ≤20/40 or a two-line difference in acuity between the eyes, or for a preverbal or nonverbal child who fails a photo screening test.

2. •

   Ocular motility evaluation.

Laboratory Tests

Usually none

Imaging Studies

Usually not necessary unless central nervous system (CNS) lesion suspected

Treatment

1. •

   Treatment depends on the age of the patient and etiology of the amblyopia.

2. •

   Glasses to align eyes in certain types of strabismus and/or to correct significant refractive errors.

3. •

   Patching or atropine eye drops are both effective depending on the type of amblyopia. Penalization of the better-seeing eye with atropine 1% drops or patching are used for varying lengths of time, usually months, depending on patient age, response, and compliance. In general, younger patients (<age 5 yr) respond faster and more fully than older children. Older children (>10 yr) who have never been treated can sometimes still respond to amblyopia therapy.

4. •

   Digital viewing devices that selectively stimulate the amblyopic eye are currently under development and beginning to be marketed as treatment for amblyopia.

5. •

   Surgery for deprivation amblyopia (i.e., congenital cataract, severe congenital ptosis).

Chronic Rx

1. •

   Maintenance treatment with glasses, patching, or atropine may be necessary until age 9 or 10 yr.

2. •

   Monitoring until visual maturity, which occurs around age 9 or 10 yr, is important to avoid relapses.

Referral

To ophthalmologist if vision is compromised

Pearls & Considerations

Comments

1. •

   The earlier the diagnosis, the better the outcome. Amblyopia is more responsive to treatment in children younger than 5 years of age. Although the average treatment response is weaker in children over age 5 years, some older children show response to treatment.

2. •

   The success of therapy is highly dependent on treatment compliance.

3. •

   Amblyopia recurs in 25% of children after patching is discontinued.

Suggested Reading

• Y.S. Bradfield: Identification and treatment of amblyopia. Am Fam Physician. 87:348–352 2013 23547551