Should Botulinum Toxin Be Used To Treat Dry Eye Disease? A Randomized Comparative Study.

To evaluate the effectiveness, complications, and side effects of botulinum toxin injection into the medial lower eyelid for the treatment of dry eye disease.

Prospective, double-blind, randomized, comparative eye-to-eye interventional study

Dry eye patients with a similar degree of dry eye in both eyes who were treated with non-preservative artificial tears for at least 1 month and in whom dry eye symptoms persisted with positive fluorescein corneal staining were enrolled. Exclusion criteria were dry eye attributable to eyelid abnormalities, severe dry eye, nasolacrimal duct obstruction, and active corneal infection. In each patient, a subcutaneous injection of 3.3 U of botulinum toxin type A was administered in the medial part of the randomly selected lower eyelid while 2.5 U of the same was administered to the second lower eyelid. Complete subjective and objective evaluations were performed at baseline and 2, 8, 12, and 16 weeks after the intervention.

Eleven patients with a mean age of 64.63 years were included. Dry eye symptoms assessed by the ocular surface disease index (OSDI) score improved significantly after treatment in both the 3.3 and 2.5 U groups. Eight of eleven (72.7%) eyes in both groups had improved OSDI scores. Modified Oxford grading scheme tended to improve after treatment, but statistically significant improvement was noted only at 2 weeks post-treatment in both groups (p = 0.021 and 0.009 respectively). Comparison of post-treatment OSDI score, Tear film break-up time, Schirmer test, and modified Oxford grading scheme between the 3.3 and 2.5 U groups showed no significant difference at any time point of the study. Average injection pain score was 3.41/10. 

Both 3.3 and 2.5 U botulinum toxin injections improved dry eye symptoms in up to three-quarters of the patients.