Effect of eyelid botulinum toxin injection on lacrimal drainage

PURPOSE: To determine the effect of eyelid botulinum toxin injection on the lacrimal drainage and to assess the use of botulinum toxin in dry eye conditions. METHODS: Prospectively, three test groups were examined and one lacrimal system investigated in each person in each group. Botulinum toxin A (3.75 IU) was injected into the medial part of 13 lower eyelids of 13 normal test subjects and the medial part of nine lower eyelids in nine patients with dry eyes. A dose of 2.5 IU was injected into the medial part of 10 lower eyelids and the medial part of 10 upper eyelids of 10 patients with dry eyes. The drop test was used to determine the lacrimal drainage capacity and the blink output, before and after the injection. The subjective effect of the botulinum toxin injection on eye comfort was investigated. RESULTS: Three weeks after lower eyelid botulinum toxin injection, the mean blink output was reduced to 64% (1.19 of 1.87; P < .001) and 70% (0.94 of 1.35; P < .001) of the baseline values in the groups of normal subjects and patients, respectively. After injection in both the upper and lower eyelid, the mean blink output was reduced to 38% (0.54 of 1.41; P < .001) of the baseline value. The patients with dry eyes reported an improved eye comfort in six of nine cases after injection in the lower eyelid and in seven of 10 cases after injection in both the upper and lower eyelid. Adverse effects included one case of increased discomfort for 3 weeks after injection. CONCLUSION: Injection of botulinum toxin into the medial part of the eyelids decreased the lacrimal drainage, suggesting a new way to treat dry eye conditions. Further studies are required to assess the clinical value of this treatment.