Definition

Amblyopia is a syndrome characterized by a degradation of visual acuity and an inhibition of visual information processing secondary to inadequate visual stimulation.

Symptoms

The symptoms and signs associated with amblyopia include, but are not limited to, the following:

1. Reduced acuity in affected eye
2. Poor depth judgment
3. Head tilt/turn
4. Lack of coordination; reduced ability to visually direct and coordinate movement (781.3)
5. Anisometropia (367.31)
6. Strabismus (378)

Diagnostic Factors

Amblyopia is characterized by one or more of the following diagnostic findings:

1. Reduced acuity in affected eye which does not normalize with the appropriate refractive prescription
2. Inability to maintain stable foveal fixation
3. Suppression of binocular vision
4. Spatial distortion
5. Reduced stereopsis
6. Reduced accommodative facility
7. Inaccurate ocular motor efficiency
8. Asymmetry in performance between the two eyes in the areas of ocular motor and visual information processing skills

NOTE: Additional testing may be appropriate as part of the differential diagnostic workup for accommodative dysfunction to rule out other concurrent medical conditions and to differentiate associated visual conditions.

Therapeutic Considerations

1. Management
   
   The doctor of optometry determines appropriate diagnostic and therapeutic modalities, and frequency of evaluation and follow-up, based upon the urgency and nature of the patient’s condition and unique needs. The management of the case and duration of treatment would be affected by:
    
   1. The severity of symptoms and diagnostic factors including onset and duration of the problem
   2. Implications of patient’s general health and associated visual condition
   3. Extent of visual demands placed upon the individual
   4. Patient compliance
   5. Prior interventions
   6. Other associated anomalies such as anisometropia or strabismus
       
2. Treatment
   
   A small percentage of cases are successfully managed by prescription of therapeutic lenses and/or prisms. However, most amblyopia requires orthoptics/vision therapy. Optometric vision therapy usually incorporates the prescription of specific treatments in order to:
    
   1. Eliminate any anisometropia
   2. Stabilize central foveal fixation
   3. Normalize visual acuity
   4. Normalize monocular skills, including but not limited to, oculomotor, accommodative and reaction time
   5. Minimize spatial distortion
   6. Eliminate suppression
   7. Eliminate any strabismus
   8. Integrate visual function with appropriate and accurate motor response
   9. Normalize binocular function

Duration of Treatment
 

The following treatment ranges are provided as a guide for third party claims processing and review purposes. Treatment duration will depend upon the particular patient’s condition and associated circumstances. When duration of treatment beyond these ranges is required, documentation of the medical necessity for additional treatment services may be warranted.

1. The most commonly encountered amblyopia usually requires 28 to 40 hours of office therapy.
2. Amblyopia complicated by:
   1. associated visual adaptations (e.g. abnormal retinal correspondence, eccentric fixation, spatial distortion) require additional office therapy.
   2. associated visual anomalies (e.g. strabismus, nystagmus, cataract) require additional office therapy.
   3. associated conditions such as birth defects, strabismus surgery require substantially more office therapy.

Follow-up Care

At the conclusion of the active treatment regimen, periodic follow-up evaluations should be provided at appropriate intervals. Therapeutic lenses may be prescribed at the conclusion of vision therapy for maintenance of long-term stability. Some cases may require additional therapy due to decompensation.