Today, the injection of botulinum toxin into the muscles that surround the eyes is one of the available options in the management of strabismus.
It acts inside nerve terminals by decreasing the release of acetylcholine, blocking neuromuscular transmission and thereby causing flaccid muscular paralysis.
After local or general anaesthesia has been applied, the botulinum toxin is injected directly into the selected eye muscles using a specially designed needle electrode that is connected to an electromyography (EMG) apparatus as well as to a syringe containing the botulinum toxin solution.
[1] The toxicity of botulinum toxin varies from one lot to the next; furthermore, the body may show an immunoreaction by which the efficacy of subsequent treatments is reduced.
A study performed in the 1980s found outcomes of surgery to be "more predictable and longer lasting" than those of botulinum toxin therapy.
[3] As stated in a review article of 2007, its use for strabismus "varies enormously in different cities and countries for no apparent reason.
[6] Some consider botulinum injections to be a treatment option for children with small- to moderate-angle infantile esotropia.
[10] Another study reported similar long-term success rates for infantile esotropia treated before 24 months of age by either strabismus surgery or botulinum toxin treatment.
[1] It is also under investigation whether the injection of bupivacaine into extraocular muscles is of possible therapeutic use for treating some forms of strabismus, be it alone or in combination with botulinum toxin.