Strabismus

What is Strabismus?

Strabismus is a sensory and neuromuscular anomaly of binocular integration resulting in the failure to maintain bifoveal alignment manifesting in a divergent (exotropia) or convergent (esotropia) deviation of the nonfixating eye.

Symptoms

The symptoms and signs associated with strabismus include the following:

1. Occasional or constant eye turn
2. Diplopia
3. Poor depth perception
4. Head tilt/turn
5. Closing or covering one eye

Diagnostic Factors

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

1. Manifest angle of eye deviation
2. Deficient vergence abilities, reduced ranges of fusion with poor depth perception/stereopsis
3. Diplopia
4. Sensory adaptations (e.g., suppression, amblyopia, abnormal retinal correspondence)

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

Therapeutic Considerations

A. Management

The doctor of optometry determines appropriate diagnostic and therapeutic modalities and frequency of evaluation and follow-up on the basis of 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 the following factors:

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 conditions
3. Extent of visual demands placed on the individual
4. Patient compliance
5. Prior interventions

B. Treatment

A small percentage of cases are successfully managed by prescription of therapeutic lenses or prisms. However, most patients with strabismus require orthoptics and/or vision therapy. Optometric vision therapy usually incorporates the prescription of specific treatments to achieve the following:

1. Normalize ocular motor control
2. Normalize spatial localization skills
3. Normalize accommodative abilities
4. Eliminate sensory adaptations
5. Establish fusion response at all distances and in all fields of movement
6. Normalize accommodative/convergence relation
7. Integrate oculomotor function with information processing

Duration of Treatment

The following treatment ranges are provided as a guide for third-party claims processing and review purposes. Treatment duration will depend on 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.

Exotropia

1. The most commonly encountered intermittent exotropia usually requires 36 to 48 hours of office therapy.
2. The most commonly encountered constant exotropia usually requires 50 to 64 hours of office therapy.
3. Exotropia complicated by:
   • Associated visual adaptations (e.g., amblyopia, abnormal retinal correspondence) require additional office therapy.
   • Associated visual anomalies (e.g., cyclotropia, hypertropia) require additional office therapy.
   • Associated conditions such as stroke, head trauma, and strabismus surgery require substantially more office therapy.

Esotropia

1. The most commonly encountered intermittent esotropia usually requires 40 to 52 hours of office therapy.
2. The most commonly encountered constant esotropia usually requires 60 to 75 hours of office therapy.
3. Esotropia complicated by:
   • Associated visual adaptations (e.g., suppression, amblyopia, abnormal retinal correspondence)require additional office therapy.
   • Associated visual anomalies (e.g., cyclotropia, hypertropia) require additional office therapy.
   • Associated conditions such as stroke, head trauma, and 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 because of decompensation.