Indications, Techniques, and Results
Clinical trials using botulinum toxin for the treatment of strabismus have shown this agent to be most effective in the following conditions:
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small- to moderate-angle esotropia and exotropia (<40Δ)
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postoperative residual strabismus (2–8 weeks following surgery or later)
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acute paralytic strabismus (especially sixth nerve palsy; sometimes fourth nerve palsy), to eliminate diplopia while the palsy resolves
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active thyroid eye disease (Graves disease) or inflamed or pre-phthisical eyes, when surgery is inappropriate
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as a supplement to medial rectus muscle recession for large-angle infantile esotropia or lateral rectus muscle recession for large-angle exotropia
When used to treat patients with strabismus, the toxin is injected directly, with a small-gauge needle, into selected EOMs. Injections into the EOMs may be performed with the use of a portable electromyographic device, although experienced practitioners often dispense with electromyography. In adults, injections are performed with topical anesthetic; in children, general anesthesia is usually necessary (Videos 14-12, 14-13).
VIDEO 14-12 Strabismus surgery: botulinum medial rectus under general anesthetic.
Courtesy of John D. Ferris, FRCOphth, and Peter E. J. Davies, FRANZCO, MPH.
VIDEO 14-13 Strabismus surgery: botulinum medial rectus.
Courtesy of John D. Ferris, FRCOphth, and Peter E. J. Davies, FRANZCO, MPH.
Multiple injections may be required, particularly in adults. As with surgical treatment, results are best when there is fusion to stabilize the alignment. Botulinum toxin injection is usually not effective in patients with large deviations, restrictive or mechanical strabismus (trauma, chronic thyroid eye disease), or secondary strabismus wherein a muscle has been overly recessed. Injection is ineffective in A and V patterns, DVDs, and chronic paralytic strabismus. The long-term recovery rate for patients with acute sixth nerve palsy treated with observation alone is similar to that for patients who receive botulinum toxin.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.