Paralysis of the orbicularis muscle of the eye using botulinum toxin type A in the treatment for dry eye.

[PURPOSE] To evaluate the efficacy of botulinum toxin type A injection to cause orbicularis eyelid muscle paralysis to improve dry eye signs and symptoms.

[METHODS] A prospective, randomized, comparative eye-to-eye and interventional study was performed. Patients with dry eye symptoms and positive fluorescein corneal staining were included. Randomly one eyelid received a subcutaneous injection of botulinum toxin in the medial orbicularis muscle portion of the lower eyelid, and the other eye received placebo. The subjective evaluation was achieved with a questionnaire assessing symptoms, quality of vision and ocular comfort level. The objective evaluation included the measurement of the tear film break-up time (TBUT), Schirmer's test and corneal and conjunctival staining.

[RESULTS] Twenty patients were included with a mean age of 59.5 years. Two weeks after the botulinum toxin injection, all patients showed a decrease in the horizontal movement of the lower eyelid when blinking. The eyes in the active treatment group showed better scores compared with the sham group in four symptoms 4 weeks after the treatment. The TBUT was higher at 1 and 3 months in the active treatment group. The corneal and conjunctival staining were significantly lower in the active treatment group at 1 and 3 months, and the Schirmer's test showed better measurements in the same group at 2 weeks, 1 month and 3 months. There were no adverse events reported.

[CONCLUSIONS] The injection of botulinum toxin A in the medial part of the lower eyelid is an effective and safe procedure that temporally improves some of the signs and symptoms of patients with dry eye.