Complications of Preseptal Versus Pretarsal Botulinum Toxin Injection in Benign Essential Blepharospasm: A Randomized Controlled Trial

Abstract

The purpose of this study was to compare ocular complications and efficacy of preseptal (PST) versus those of pretarsal (PTS) botulinum toxin type A (BoNT-A) therapy in cases of benign essential blepharospasm (BEB). Randomized clinical trial. Setting: university hospital. 24 participants with BEB were enrolled from August 2019 to June 2020. All patients and the outcome evaluator were masked to the injection allocation. for each participant, 1 eye was randomized to receive PST BoNT-A injection, and the fellow eye received PTS BoNT-A injection of the same amount from a single investigator. At baseline, 1, and 3 months after the injection, we collected the symptoms of tearing, lagophthalmos, ptosis, and diplopia and measured margin-to-reflex distance (MRD) 1 and 2 (mm), degree of lagophthalmos (mm), presence of ectropion, entropion, limitation of ocular motility, tear film breakup time (second), Schirmer's test (mm) , ocular surface staining scores (Oxford's scheme), and Jankovic rating scale of both eyes separately. Main outcome measurements were complications of the injection. There were statistically significant higher rates of self-reported lagophthalmos in PTS (n=12; 52.17%) than in PST (n=7; 30.43%) BoNT-A injections (P=.024) and significantly higher estimated measurements of lagophthalmos in PTS (0.59 mm; 95% confidence interval [CI]: 0.44-0.72) than in PST (0.26 mm; 95% CI: 0.12-0.40) injection at 1 month using an interaction model (Bonferroni-corrected P=.001). No significant differences in the efficacy and other complication outcomes between the injection locations were observed. PTS BoNT-A injection had a higher rate of lagophthalmos than PST BoNT-A injection for BEB.