On September 11, 2013 the U.S. Food and Drug Administration (FDA) announced its approval of Botox (onabotulinumtoxinA) for the treatment of wrinkles at the corners of the eyes, commonly called crow’s feet.
Crows’ feet – or lateral canthal lines, as they known scientifically – are thought to be caused by repeated muscle contractions associated with making facial expressions, like smiling. Over time, the folding of the skin caused by these contractions creates permanent lines in the skin.
Botox is made from a toxic protein called botulinum which is produced by the bacterium Clostridium botulinum. In large doses, this toxin causes botulism, a disease which can cause muscle paralysis. In the small doses used in Botox, however, it can temporarily relax the muscles responsible for facial wrinkles, leading to an improved appearance.
It also has applications in treating several medical conditions, such as cervical dystonia (painful neck muscle contractions), blepharospasm (involuntary closing of one or both eyelids), strabismus (misalignment of the eyes), excessive sweating, achalasia (spasms in the esophagus which cause swallowing difficulties), chronic pain and migraines.
Botox is administered by injecting it into the appropriate muscle. It usually takes about two to four days to see results and it tends to last for anywhere from four to six months. It must be periodically reinjected in order to maintain results.
Botox’s safety and effectiveness in treating crow’s feet was confirmed in two clinical trials. The studies included 833 participants who had moderate to severe crow’s feet. The participants were randomly assigned to one of two groups who received either Botox injections or injections of an inactive placebo.
People in the Botox group had greater improvement in the appearance of their crow’s feet than those in the placebo group.
The most common side effect that people in the studies experienced was swelling in the eyelid near the injection site.
Other common side effects which people may experience with Botox include: bruising, headache, respiratory infection, flu syndrome, drooping of the upper eyelid, nausea and indigestion.
The package insert for Botox contains a black box warning that the botulinum toxin may potentially spread beyond the injection site, causing symptoms similar to botulism, such as swallowing or breathing problems. However, there have not been any confirmed serious cases of this occurring when is used as recommended.
OnabotulinumtoxinA is marketed under the names Botox and Botox Cosmetic by its manufacturer, Allergan, Inc., which is located in Irvine, CA.
While its competitors – Medicis’ Dysport, Merz Aesthetics, Inc’s Xeomin and Solstice Neurosciences, Inc.’s Myobloc – work in a similar manner, Botox is currently the only approved treatment for crow’s feet. It was previously approved in 2002 to treat frown lines between the eyebrows.
Botox’s FDA approval for treating crow’s feet most likely won’t have any effect on how doctors use the injections, experts contend, because it has already been used off-label for this purpose for several years. Receiving the FDA’s official stamp of approval, however, does provide added confidence for doctors and their patients that it is a safe and effective treatment for eye wrinkles.
Written by: Nancy Schimelpfening