Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ACUTE

primary strabismus

1st line – correction of refractive errors

Back
ACUTE
|
primary strabismus
1st line – 

correction of refractive errors

The visual acuity of all patients with strabismus should be assessed, and if a significant refractive error is present, it should be corrected using spectacles or contact lenses.

This may lead to realignment of the eyes in accommodative esotropia (with correction of hyperopia) and some cases of intermittent exotropia.

In children, the refractive error needs to be measured under cycloplegia (e.g., 30 minutes after the application of cycloplegic eye drops such as cyclopentolate 1%).

Reversal of monovision (if present) may be necessary to resolve symptoms for some adult patients.[28]​​

If esotropia does not respond to an initial prescription or if it recurs after surgery, repeat the cycloplegic refraction before diagnosing a non-accommodative component.[2]

Consider – treatment of amblyopia and/or diplopia

Back
ACUTE
|
primary strabismus
Consider – 

treatment of amblyopia and/or diplopia

Treatment recommended for SOME patients in selected patient group

The treatment of amblyopia should be undertaken in children and considered in young adolescents before, or in parallel with, correction of the strabismus.[30]

Treatment of amblyopia involves occlusion of the sound eye with a patch, or penalization of the sound eye either by optical means (i.e., spectacles), or pharmaceutical means (atropine 1% eye drops), or both.[29]​ See Amblyopia (Treatment algorithm).

Diplopia, which may be absent in children, is treated with occlusion or prisms.[28]​​

In children, when amblyopia is present, the sound eye is covered (occluded), and in the absence of amblyopia, the nondeviating eye is covered. If neither amblyopia nor an obviously deviating eye is present, alternate patching is used. To prevent the development of amblyopia, patching should be limited to 6 hours a day, with a recommended duration of between 2 and 6 hours.[2]​ Occlusion should be used with caution in intermittent exotropia due to the risk of developing amblyopia.

Prisms are used in children with acute-onset strabismus to promote fusion and avoid amblyopia, but are rarely helpful in intermittent exotropia. In adults, they can be used to treat diplopia.[28]​ Prisms superimpose the images of the two eyes when the visual axes are not aligned, thus allowing fusion. As they do not change the position of the eyes, these remain deviated under the prism. Prisms work best in comitant strabismus and if the angle of the deviation is small.

2nd line – extraocular muscle surgery

Back
ACUTE
|
primary strabismus
2nd line – 

extraocular muscle surgery

The definitive treatment for most cases of primary and secondary strabismus is extraocular muscle surgery, particularly when the strabismus has been stable over several months.[34]

Surgical intervention should be considered in infantile strabismus, comitant strabismus, sensory strabismus, and all stable misalignments (including paralytic strabismus). In acquired misalignments (e.g., paralytic), it is important to wait 6 to 12 months for potential spontaneous recovery and for stabilization.

The basic principles of surgery are to increase (strengthen) or decrease (weaken) muscle function. This can be achieved by recessions, resections, and plications. Recessions involve moving the insertion of a muscle posteriorly on the eye to weaken the muscle. Resections involve removing a section of the muscle to strengthen it, which can also be done by plication. The use of adjustable sutures allows for refinement of the position of the extraocular muscle in the early postoperative period and may result in improved surgical outcomes in some patients.[35]

Decisions on whether and when to operate are made by the consulting ophthalmologist and may be complex in some patients.[2][18]​​​[36]​​​ Severe complications and poor or very poor outcomes are estimated to arise in 1 per 400 and 1 per 2400 surgeries, respectively.[37]​​

Consider – treatment of amblyopia and/or diplopia

Back
ACUTE
|
primary strabismus
Consider – 

treatment of amblyopia and/or diplopia

Treatment recommended for SOME patients in selected patient group

The treatment of amblyopia should be undertaken in children and considered in young adolescents before, or in parallel with, correction of the strabismus.[30]

Treatment of amblyopia involves occlusion of the sound eye with a patch, or penalization of the sound eye either by optical means (i.e., spectacles), or pharmaceutical means (atropine 1% eye drops), or both.[29]​ See Amblyopia (Treatment algorithm).

Diplopia, which may be absent in children, is treated with occlusion or prisms.[28]​​

In children, when amblyopia is present, the sound eye is covered (occluded), and in the absence of amblyopia, the nondeviating eye is covered. If neither amblyopia nor an obviously deviating eye is present, alternate patching is used. To prevent the development of amblyopia, patching should be limited to 6 hours a day, with a recommended duration of between 2 and 6 hours.[2]​ Occlusion should be used with caution in intermittent exotropia due to the risk of developing amblyopia.

Prisms are used in children with acute-onset strabismus to promote fusion and avoid amblyopia, but are rarely helpful in intermittent exotropia. In adults, they can be used to treat diplopia.[28]​ Prisms superimpose the images of the two eyes when the visual axes are not aligned, thus allowing fusion. As they do not change the position of the eyes, these remain deviated under the prism. Prisms work best in comitant strabismus and if the angle of the deviation is small.

3rd line – chemodenervation

Back
ACUTE
|
primary strabismus
3rd line – 

chemodenervation

OnabotulinumtoxinA (botulinum toxin type A) selectively blocks the release of acetylcholine at the neuromuscular junction and leads to chemodenervation. If injected intramuscularly, a temporary flaccid paralysis results, with muscle function usually recovering within 2 months. It is therefore considered most helpful in the treatment of strabismus that is expected to change, such as postoperative residual strabismus, acute paralytic strabismus (particularly that secondary to abducens nerve palsy), and active thyroid eye disease (Graves disease).

Surgical treatment is usually preferable to chemodenervation because it is permanent and may be more effective.[36][38]​​​ However, chemodenervation can alleviate strabismus secondary to acute paresis of the abducens nerve (cranial nerve VI) by weakening the medial rectus muscle while the acute insult heals. Repeated injections can also be used as a long-term alternative to surgery in patients who are not eligible for surgery.[39]​ Chemodenervation might also be useful in the treatment of consecutive exotropia, especially after multiple eye muscle surgeries.[40]

The main adverse effect is ptosis (in up to 40% of patients), which is usually reversible.[38]

Primary options

onabotulinumtoxinA: consult specialist for guidance on dose

Consider – treatment of amblyopia and/or diplopia

Back
ACUTE
|
primary strabismus
Consider – 

treatment of amblyopia and/or diplopia

Treatment recommended for SOME patients in selected patient group

The treatment of amblyopia should be undertaken in children and considered in young adolescents before, or in parallel with, correction of the strabismus.[30]

Treatment of amblyopia involves occlusion of the sound eye with a patch, or penalization of the sound eye either by optical means (i.e., spectacles), or pharmaceutical means (atropine 1% eye drops), or both.[29]​ See Amblyopia (Treatment algorithm).

Diplopia, which may be absent in children, is treated with occlusion or prisms.[28]​​

In children, when amblyopia is present, the sound eye is covered (occluded), and in the absence of amblyopia, the nondeviating eye is covered. If neither amblyopia nor an obviously deviating eye is present, alternate patching is used. To prevent the development of amblyopia, patching should be limited to 6 hours a day, with a recommended duration of between 2 and 6 hours.[2]​ Occlusion should be used with caution in intermittent exotropia due to the risk of developing amblyopia.

Prisms are used in children with acute-onset strabismus to promote fusion and avoid amblyopia, but are rarely helpful in intermittent exotropia. In adults, they can be used to treat diplopia.[28]​ Prisms superimpose the images of the two eyes when the visual axes are not aligned, thus allowing fusion. As they do not change the position of the eyes, these remain deviated under the prism. Prisms work best in comitant strabismus and if the angle of the deviation is small.

Plus – over-minus prescription or occlusion

Back
ACUTE
|
primary strabismus
|
with intermittent exotropia
Plus – 

over-minus prescription or occlusion

Treatment recommended for ALL patients in selected patient group

In an over-minus prescription, spectacles with a higher than necessary negative power may be prescribed to reduce the angle of deviation and promote binocularity, although this is only a temporary measure and may cause asthenopia.[31][32]

Occlusion involves covering one eye with a patch and may result in improved control of the deviation. One Cochrane review found that patching conferred a clinical benefit compared with observation in children ages 12 months to 10 years.[31] Occlusion is undertaken with caution, owing to the risk of developing amblyopia. In the presence of amblyopia, the sound eye is covered, and in its absence, alternate patching for 2-6 hours a day is used.[2]

Either of these techniques can be used and the other should be considered if the first fails.[32]

secondary strabismus

1st line – treatment of underlying cause and correction of refractive errors

Back
ACUTE
|
secondary strabismus
1st line – 

treatment of underlying cause and correction of refractive errors

As secondary strabismus may result from a number of underlying pathologies (such as cranial nerve and supranuclear palsies, Graves disease, orbital fractures, and myasthenia gravis), it is essential that these conditions be identified and treated.

The visual acuity of all patients with strabismus should be assessed, and if a significant refractive error is present, it should be corrected using spectacles or contact lenses.

This may lead to realignment of the eyes in accommodative esotropia (with correction of hyperopia) and some cases of intermittent exotropia.

If esotropia does not respond to an initial prescription or if it recurs after surgery, repeat the cycloplegic refraction before diagnosing a non-accommodative component.[2]

Consider – treatment of amblyopia and/or diplopia

Back
ACUTE
|
secondary strabismus
Consider – 

treatment of amblyopia and/or diplopia

Treatment recommended for SOME patients in selected patient group

The treatment of amblyopia should be undertaken in children and considered in young adolescents before, or in parallel with, correction of the strabismus.[30]

Treatment of amblyopia involves occlusion of the sound eye with a patch, or penalization of the sound eye either by optical means (i.e., spectacles), or pharmaceutical means (atropine 1% eye drops), or both.[29]​ See Amblyopia (Treatment algorithm).

Diplopia, which may be absent in children, is treated with occlusion or prisms.[28]​​

In children, when amblyopia is present, the sound eye is covered (occluded), and in the absence of amblyopia, the nondeviating eye is covered. If neither amblyopia nor an obviously deviating eye is present, alternate patching is used. To prevent the development of amblyopia, patching should be limited to 6 hours a day, with a recommended duration of between 2 and 6 hours.[2] Occlusion should be used with caution in intermittent exotropia due to the risk of developing amblyopia.

Prisms are used in children with acute-onset strabismus to promote fusion and avoid amblyopia, but are rarely helpful in intermittent exotropia. In adults, they can be used to treat diplopia.[28]​ Prisms superimpose the images of the two eyes when the visual axes are not aligned, thus allowing fusion. As they do not change the position of the eyes, these remain deviated under the prism. Prisms work best in comitant strabismus and if the angle of the deviation is small.

2nd line – extraocular muscle surgery

Back
ACUTE
|
secondary strabismus
2nd line – 

extraocular muscle surgery

The definitive treatment for most cases of primary and secondary strabismus is extraocular muscle surgery, particularly when the strabismus has been stable over several months.[34]

Surgical intervention should be considered in infantile strabismus, comitant strabismus, sensory strabismus, and all stable misalignments (including paralytic strabismus). In acquired misalignments (e.g., paralytic), it is important to wait 6 to 12 months for potential spontaneous recovery and for stabilization.

The basic principles of surgery are to increase (strengthen) or decrease (weaken) muscle function. This can be achieved by recessions, resections, and plications. Recessions involve moving the insertion of a muscle posteriorly on the eye to weaken the muscle. Resections involve removing a section of the muscle to strengthen it, which can also be done by plication. The use of adjustable sutures allows for refinement of the position of the extraocular muscle in the early postoperative period and may result in improved surgical outcomes in some patients.[35]

Decisions on whether and when to operate are made by the consulting ophthalmologist and may be complex in some patients.[2][18]​​​[36]​​​ Severe complications and poor or very poor outcomes are estimated to arise in 1 per 400 and 1 per 2400 surgeries, respectively.[37]​​

Consider – treatment of amblyopia and/or diplopia

Back
ACUTE
|
secondary strabismus
Consider – 

treatment of amblyopia and/or diplopia

Treatment recommended for SOME patients in selected patient group

The treatment of amblyopia should be undertaken in children and considered in young adolescents before, or in parallel with, correction of the strabismus.[30]

Treatment of amblyopia involves occlusion of the sound eye with a patch, or penalization of the sound eye either by optical means (i.e., spectacles), or pharmaceutical means (atropine 1% eye drops), or both.[29]​ See Amblyopia (Treatment algorithm).

Diplopia, which may be absent in children, is treated with occlusion or prisms.[28]​​

In children, when amblyopia is present, the sound eye is covered (occluded). If neither amblyopia nor an obviously deviating eye is present, alternate patching may be used to avoid the development of amblyopia. Patching should be limited to 6 hours a day, with a recommended duration of between 2 and 6 hours.[2]

Prisms are used in children with acute-onset strabismus to promote fusion and avoid amblyopia, but are rarely helpful in intermittent exotropia. In adults, they can be used to treat diplopia.[28]​ Prisms superimpose the images of the two eyes when the visual axes are not aligned, thus allowing fusion. As they do not change the position of the eyes, these remain deviated under the prism. Prisms work best in comitant strabismus and if the angle of the deviation is small.

3rd line – chemodenervation

Back
ACUTE
|
secondary strabismus
3rd line – 

chemodenervation

OnabotulinumtoxinA (botulinum toxin type A) selectively blocks the release of acetylcholine at the neuromuscular junction and leads to chemodenervation. If injected intramuscularly, a temporary flaccid paralysis results, with muscle function usually recovering within 2 months. It is therefore considered most helpful in the treatment of strabismus that is expected to change, such as postoperative residual strabismus, acute paralytic strabismus (particularly that secondary to abducens nerve palsy), and active thyroid eye disease (Graves disease).

Surgical treatment is usually preferable to chemodenervation because it is permanent and may be more effective.[36][38]​​​ However, chemodenervation can alleviate strabismus secondary to acute paresis of the abducens nerve (cranial nerve VI) by weakening the medial rectus muscle while the acute insult heals. Repeated injections can also be used as a long-term alternative to surgery in patients who are not eligible for surgery.[39]​ Chemodenervation might also be useful in the treatment of consecutive exotropia, especially after multiple eye muscle surgeries.[40]

The main adverse effect is ptosis (in up to 40% of patients), which is usually reversible.[38]

Primary options

onabotulinumtoxinA: consult specialist for guidance on dose

Consider – treatment of amblyopia and/or diplopia

Back
ACUTE
|
secondary strabismus
Consider – 

treatment of amblyopia and/or diplopia

Treatment recommended for SOME patients in selected patient group

The treatment of amblyopia should be undertaken in children and considered in young adolescents before, or in parallel with, correction of the strabismus.[30]

Treatment of amblyopia involves occlusion of the sound eye with a patch, or penalization of the sound eye either by optical means (i.e., spectacles), or pharmaceutical means (atropine 1% eye drops), or both.[29]​​ See Amblyopia (Treatment algorithm).

Diplopia, which may be absent in children, is treated with occlusion or prisms.[28]​​

In children, when amblyopia is present, the sound eye is covered (occluded), and in the absence of amblyopia, the nondeviating eye is covered. If neither amblyopia nor an obviously deviating eye is present, alternate patching is used. To prevent the development of amblyopia, patching should be limited to 6 hours a day, with a recommended duration of between 2 and 6 hours.[2]​ Occlusion should be used with caution in intermittent exotropia due to the risk of developing amblyopia.

Prisms are used in children with acute-onset strabismus to promote fusion and avoid amblyopia, but are rarely helpful in intermittent exotropia. In adults, they can be used to treat diplopia.[28]​ Prisms superimpose the images of the two eyes when the visual axes are not aligned, thus allowing fusion. As they do not change the position of the eyes, these remain deviated under the prism. Prisms work best in comitant strabismus and if the angle of the deviation is small.

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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