• Oculoplastics/Orbit

    Review of: Complications of preseptal versus pretarsal botulinum toxin injection in benign essential blepharospasm: A randomized controlled trial

    Sanguandikul L, Apinyawasisuk S, Jariyakosol S, et al. American Journal of Ophthalmology, December 2021

    Investigators compared the rate of ocular complications, particularly lagophthalmos, between preseptal and pretarsal botulinum toxin injections in patients with benign essential blepharospasm (BEB).

    Study design

    This was a double-blind, randomized controlled trial of 24 Thai patients with BEB who received preseptal botulinum toxin in 1 eye and the same amount of pretarsal botulinum toxin in the other eye. Patients were evaluated at baseline and 1 and 3 months after injection for symptoms of ptosis, tearing, diplopia, and lagophthalmos. The severity and frequency of BEB were measured with the Jankovic rating scale.


    Pretarsal injection resulted in statistically significant higher rates of self-reported lagophthalmos (52.2%) compared with preseptal injection (30.4%), as well as higher measured lagophthalmos (0.59 mm vs, 0.26 mm, respectively) at 1 month post-injection. Patients also reported more tearing in the eyes given pretarsal injections. No other differences were observed in any of the other symptoms or objective measurements. At 3 months post-injection, the lagophthalmos on the pretarsal injection side did not return to baseline.


    Although this was a well-designed study, the sample size is small and other differences in the symptoms and objective measurements may be seen in a larger study. In addition, it is possible that the patients may not have been truly masked to the location of the injections.

    Clinical significance

    Pretarsal injection of botulinum toxin results in greater degrees of lagophthalmos than preseptal injection. This may reflect a sign of greater efficacy of the toxin in the pretarsal site, rather than a complication. Although there was a measured difference between the 2 sides, the difference may be clinically insignificant. The clinician should be aware of these differences in injection sites and may need to counsel patients more carefully with regard to the use of ocular lubrication. In addition, it is possible that less toxin may be needed in the pretarsal location to provide the same effect as that seen in the preseptal location.