title: Effect of botulinum toxin type a on tear production after treatment of lateral canthal rhytids.
abstract: OBJECTIVE
  To evaluate the incidence of temporary dry eye and the effects on lacrimal gland tear production after treatment of lateral canthal rhytids with botulinum toxin type A injections.
  
  
  METHODS
  Twenty-six crow's feet areas were injected with botulinum toxin type A in 13 women with an age range of 31 to 58 years. A total of 10 units of botulinum toxin was injected per side, with two separate injections. Schirmer 1 testing was performed before and at 1 week, 1 month, and 4 months after the injections in all patients. The test was repeated at 6 months and 9 months for the patients whose Schirmer test results were not back to baseline at the 4-month follow-up. Statistical significance was evaluated with paired t test analysis.
  
  
  RESULTS
  Overall, no statistical difference was found in Schirmer test results from baseline at 1 week (p = 0.23), 1 month (p = 0.32), or 4 months (p = 0.30) after injection. Five eyes of three patients had a significant decrease in Schirmer test results from baseline at 1 week and 1 month after injection. Three eyes of 2 patients had a significant decrease in Schirmer test results at 4 months after injection. Only one patient reported dry-eye symptoms at the 4-month follow-up. Schirmer test results of two eyes of one patient remained significantly lower than baseline at 6 months follow-up, which returned to the normal range at 9 months.
  
  
  CONCLUSIONS
  Botulinum toxin for lateral canthal rhytids usually does not suppress tear production. However, decreased tear production after botulinum toxin injection for crow's feet is a possible complication and patients should be advised of the small but definite risk of a temporary dry eye.
authors.affiliation: Department of Ophthalmology, Cullen Eye Institute, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: Yonca Ozkan
authors.initials: YO
authors.lastname: Arat
authors.forename: Michael T
authors.initials: MT
authors.lastname: Yen
mesh_terms: D000328:Adult; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage* / Q000009:adverse effects; D015352:Dry Eye Syndromes / Q000139:chemically induced; D005143:Eyelids; D005152:Facial Muscles / Q000187:drug effects; D005260:Female; D006801:Humans; D007267:Injections; D007765:Lacrimal Apparatus / Q000187:drug effects; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000008:administration & dosage* / Q000009:adverse effects; D015595:Skin Aging / Q000187:drug effects*; D013666:Tears / Q000378:metabolism*
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A