title: Paralysis of the orbicularis muscle of the eye using botulinum toxin type A in the treatment for dry eye.
abstract: OBJECTIVE
  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.
authors.affiliation: Institute of Ophthalmology 'Conde de Valenciana', Mexico City, Mexico.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Serna-Ojeda
authors.affiliation: Institute of Ophthalmology 'Conde de Valenciana', Mexico City, Mexico.
authors.forename: Angel
authors.initials: A
authors.lastname: Nava-Castaneda
mesh_terms: D000368:Aged; D001767:Blinking / Q000502:physiology*; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage / Q000009:adverse effects*; D015352:Dry Eye Syndromes / Q000175:diagnosis / Q000188:drug therapy*; D005133:Eye Movements / Q000187:drug effects*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000008:administration & dosage / Q000009:adverse effects; D009801:Oculomotor Muscles / Q000187:drug effects* / Q000503:physiopathology; D009886:Ophthalmoplegia / Q000139:chemically induced* / Q000175:diagnosis / Q000503:physiopathology; D011446:Prospective Studies
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A
keywords: botulinum toxin; dry eye; eyelid; orbicularis muscle