Effect of Botulinum Toxin Type A on Tear Production After Treatment of Lateral Canthal Rhytids

PURPOSE: 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.