- Botulinum toxin type A (Botox Cosmetic, Allergan) injected into the periocular region for the treatment of lateral canthal
rhytids, usually does not suppress tear production.
- Surgeons should warn patients that temporary dry eye is a possibility, although a rare occurrence.
Houston—Temporary dry eye, a known complication of botulinum toxin type A (Botox Cosmetic, Allergan) for the treatment of lateral
canthal rhytids, is rare in this case but should be mentioned during the informed con sent process, according to Michael T.
Yen, MD, assistant professor of ophthalmology, Cullen Eye Institute, Baylor College of Medicine, Houston.
Michael T. Yen, MD Phone: 713/798-6100 Fax: 713/798-8739 E-mail: firstname.lastname@example.org Dr. Yen has no financial interest in any
product or company related to the subject matter of this article.
Dr. Yen and colleague Yonca O. Arat, MD, also of the Cullen Eye Institute, undertook a study to evaluate the incidence of
dry eye and the effects on tear production after treating patients with botulinum toxin for crow's feet. In 13 patients aged
31 to 58 years, they injected a moderate dose of 10 units of botulinum toxin per side with two separate injections. Using
the Schirmer test to measure tear production, they assessed the patients at baseline (before injections), at 1 week, 1 month,
and 4 months after the cosmetic treatment.
"In our study, we showed that botulinum toxin's effect in terms of inducing temporary dry eye was not statistically significant,"
explained Dr. Yen, a specialist in ophthalmic plastic, lacrimal, and orbital surgery. "No statistical difference was found
in Schirmer test results from baseline at 1 week, 1 month, and 4 months after injection." The study results were published
in Ophthalmic Plastic and Reconstructive Surgery (2007;23:22-24.)
None of the patients developed dry-eye symptoms at the 1-week and 1-month time points, he noted. Two patients, however, had
significantly lower Schirmer test results. "We decided to follow these patients longer to make sure that we didn't cause a
permanent decrease in tear production," Dr. Yen said. Tear production returned to the normal range at 6 and 9 months, respectively,
Botulinum toxin, a neurotoxin, works by blocking the release of acetylcholine from the nerves. According to the product information
from the manufacturer, when injected into the muscles, botulinum toxin is able to produce partial chemical denervation of
the muscle and reduce the muscle activity at the site of the injection.
"Botulinum toxin takes about 2 to 3 days for the first effects to become noticeable and probably 7 to 10 days for the full
effects to be realized," explained Dr. Yen. "It is a temporary treatment lasting 3, 4, or 5 months. The neuron recovers and
is able to release acetylcholine after a given amount of time."
The key to avoiding the complication of temporary dry eye with botulinum toxin is knowledge of the anatomy.
"Proper placement of the injections should avoid the pretarsal muscle fibers of the upper eyelid so as to reduce the risk
of affecting eyelid blinking as well as the superior lateral orbit where the lacrimal gland is located," Dr. Yen said.
In a report published in the American Journal of Ophthalmology (2000;129:481-486), the investigators discovered that botulinum toxin injections into the medial part of the upper and lower
eyelids had an effect on the lacrimal gland. The eyelids exhibited reduced blink, and there was decreased lacri mal gland
drainage. "The lacri mal gland needs to be stimulated to produce and secrete tears," Dr. Yen noted. "The botulinum toxin would
inhibit the stimulation of the lacrimal gland."
Surgeons need to know the periorbital anat o my, know where to place the injections, know the proper plane to inject into,
and must not inject too deeply to go into the orbit or lac ri mal gland. "The key is that the physician really needs to know
how the medication works, where the optimal placement of the medication is in terms of treating the wrinkles, using the proper
technique to place the medication in the proper muscles, and being aware of potential complications and how to manage them
should they occur," Dr. Yen explained.
Dr. Yen said that some limitations to the study included no control group, the variability of the Schirmer test results, no
evaluation of the ocular surface with fluorescein staining, and the fact that the same dose of botulinum toxin was used in
"Obviously, some patients [in clinical practice] may require a higher dose of botulinum toxin," he said. "A greater total
amount of toxin injected or a larger volume of injection could conceivably result in a higher incidence of lacrimal gland
involvement and a subsequent decrease in tear production."
Botulinum toxin injection is the most common cosmetic procedure performed because of its excellent success rate, convenience,
and minimal down time, so patients should be advised of all the potential complications, including the risk of temporary dry
eye, Dr. Yen concluded.