It's not just for wrinkles anymore – in fact, botulinum toxin was originally approved over a decade ago for use in treating strabismus, which is an eye condition that causes misalignment. There are two botulinum toxin preparations commercially available in the U.S. today: Botox and Myobloc. The FDA has approved Botox for two eye conditions, as well as for cervical dystonia, excessive sweating, and cosmetic use. Myobloc is approved only for cervical dystonia, which is a condition of the neck muscles that causes pain and impaired movement. Other uses for the toxin that are not yet approved include spastic disorders from trauma, stroke, multiple sclerosis, or cerebral palsy.
Botox works by inhibiting the release of acetylcholine from the neuromuscular junction, producing local paralysis. In very small doses, it is a strong muscle relaxant that lasts for about three months. Side effects include dry mouth, pain at the injection site, headache, neck pain, double vision, blurred vision, drooping eyelids, swelling of the eyelids, and dry eyes. Some patients have an allergic reaction characterized by itching, rash, wheezing, asthma, and dizziness. However, this drug is reported to be well tolerated by most patients, with a wide margin of safety.
The eye conditions treated with Botox are strabismus and blepharospasm. Strabismus includes cross-eyedness, wall-eyedness, and other misalignments where the eyes point in different directions, such as one too far up or down. The Botox web site includes full product information that reports success in treating this condition, but the home page promotes only the uses for blepharospasm and cervical dystonia. Other treatments for strabismus include surgery and eye exercises.
Blepharospasm is an abnormal spasm of the eyelid muscles, causing involuntary blinking. It may progress to facial spasms. This is a neurological problem different from blepharitis, which is an infection of the eyelid. Injection of Botox into the muscles of the eyelids is often helpful.