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Ghasem Yazdanpanah, Michael Tze-Chien Yen, Stephen C Pflugfelder; Change in Blink Rate Following Botulinum Toxin Injection in Benign Essential Blepharospasm. Invest. Ophthalmol. Vis. Sci. 2022;63(7):607 – A0308.
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© ARVO (1962-2015); The Authors (2016-present)
Benign essential blepharospasm (BEB) is characterized by involuntary twitching of eyelids, increased blinking, and photophobia. Serial injections of botulinum toxin type A (BTX-A) into the eyelid protractors, including the pretarsal orbicularis oculi muscle and corrugator supercili is the core management for BEB. Here, the blink rate was measured objectively to evaluate the effect of BTX-A injection in BEB patients.
In this prospective case series, 10 subjects with BEB managed with BTX-A injections were included after informed consent. The study was approved by Baylor College of Medicine IRB. Management history was recorded with chart review. Blink rates were measured while watching a video before injection (at least 3 months after last injection) and at follow-up within 4 weeks. The frequency of blinking and the severity of light-sensitivity were self-graded on a visual analog scale. The results are reported as median (range) and Wilcoxon test is used for non-parametric paired comparison.
Nine subjects are female, and median age was 73.5 (49-81) years. The median follow-up time is 21 (14-28) days after BTX-A injection. The duration of treatment is 70 (5-16) months with a total of 27.5 (2-51) injections. Subject graded frequency of blinking (0, normal and 5, constant blinking) was 4.5 (2-5) before BTX-A injection and decreased to 1.75 (0-4.5) at follow-up (p=0.004, Fig1A). Subject reported light-sensitivity (0, none and 5, severe) decreased from 3.5 (0-5) before injection to 2.75 (0-4) at follow-up (p=0.047, Fig 1B). The blink rate before BTX-A injection is 39 (23-64), and significantly decreased to 18.5 (1-60) blinks per minute at follow-up (p=0.004, Fig1C). The average change in blink rate is -45.2±31.2% (mean±SD, Fig 1D). Blink rate change has a significant correlation with both duration of BTX-A injection treatment (r=-0.659, p=0.037) and number of treatments (r=-0.639, p=0.047).
This is the first known report of objective reduction in blink rate after BTX-A injection in BEB patients. BTX-A injection significantly improved photophobia. Higher duration of BTX-A injection treatment or more numbers of past injections significantly correlates with higher decrease in blink rate after each injection.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.
Fig 1: (A) patient-reported frequency of blinking, (B) severity of light sensitivity, and (C) blink rate, before BTX-A injection and at follow-up. (D) change in blink rate.
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