Developments in the Treatment of Benign Essential Blepharospasm

Michael T. Yen

Disclosures

Curr Opin Ophthalmol. 2018;29(5):440-444. 

In This Article

Botulinum Toxin Injections

Botulinum toxin type A was approved by the United States Food and Drug Administration (FDA) in 1989 for the treatment of blepharospasm, and has emerged as the best short-term alleviation of blepharospasm.[3] It works by inhibiting the release of acetylcholine from the nerve terminals at the neuromuscular junction, causing the inability of the injected muscles to contract. Repeat injections are typically required every 3–4 months, and repeat injections are not always as effective as the first injection. In 1998, Anderson et al.[4] found that Botox injections are effective in up to 86% of patients with blepharospasm, but the effect only lasts less than 4 weeks in 13% of the responders.

There are a total of seven different serotypes (A–G) of botulinum toxin, but only two are commercially available and used clinically in the United States, types A and B. Botulinum toxin type A is by far the most frequently used serotype, although botulinum toxin type B has been found to be a useful treatment for blepharospasm in some patients who become refractory to botulinum type A injections.[13] There are three FDA-approved botulinum type A formulations currently available. AbobotulinumtoxinA, incobotulinumtoxinA, and onabotulinumtoxinA all share the same active neurotoxin molecule. The products differ in purification procedures and the presence or absence of accessory proteins. Clinical trials have not shown significant differences in therapeutic response or longevity amongst the three types A toxins when the appropriate equivalent dosing is used.[14]

Injection of the botulinum toxin into the orbicularis oculi, procerus, and corrugator muscles has been stated to be the most effective treatment for blepharospasm. Injection into the pretarsal orbicularis oculi muscle is believed to be particularly important for essential blepharospasm (Figure 2). Aramideh et al.[15] showed that combined pretarsal and orbital injections of botulinum toxin A can lead to an increased response to botulinum toxin A treatment compared with orbital injections alone. Pretarsal botulinum injections have also been reported to be effective in the treatment of patients with blepharospasm who showed no improvement with increasing doses of the standard subcutaneous orbital injections of botulinum toxin.[16] The authors found that although there was an increase in pain and incidence of echymosis associated with pretarsal injections, the total required botulinum toxin dose was reduced. In a direct comparison trial between pretarsal and preseptal orbicularis oculi injections of botulinum toxin A for treatment of blepharospasm and hemifacial spasm, pretarsal injections were found to have significantly higher response rates and longer durations of maximum response.[17]

Figure 2.

A sample injection pattern for the treatment of essential blepharospasm. The injections in the eyelid are targeted to the pretarsal orbicularis oculi muscles. The central area of the upper eyelid is avoided to minimize the risk of postinjection ptosis, and the medial area of the lower eyelid is avoided to minimize the risk of inferior oblique paralysis.

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