Appropriate concentration of botulinum toxin type A for dry eye disease treatment by injection into the medial lower eyelid. A randomized comparative study

Abstract

Abstract This prospective, double-blind, randomized, comparative eye-to-eye interventional study aimed to determine the appropriate concentration of botulinum toxin type A for dry eye disease treatment in terms of effectiveness, complications, and cost-effectiveness. Patients with dry eye having a similar degree in both eyes treated with non-preservative artificial tears for at least 1 month and persistent dry eye symptoms were enrolled. 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 and 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 intervention. Eleven patients (mean age 64.63 ± 14.81 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. Comparison of post-treatment OSDI scores, tear film break-up time (TBUT), Schirmer’s 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. Conclusions: Both 3.3 and 2.5 U botulinum toxin injections improved dry eye symptoms.