Quantitative assessment of botulinum toxin injection on blink rate in blepharospasm

ABSTRACT

Purpose

To objectively measure the blink rate in patients with blepharospasm managed by botulinum toxin type-A injections.

Methods

In this prospective, non-interventional case series, the complete blink rates of subjects were measured before incobotulinumtoxina injection and at follow-up within 4 weeks using slow-motion video-taping. Additionally, subjects graded the frequency of blinking, the severity of light-sensitivity, and the severity and frequency of dry eye symptoms on a categorical visual analog scale. The results are reported as median (range).

Results

Ten subjects were enrolled, with nine females. The total duration of treatment was 70 (5–116) months with total of 27.5 (2–51) injections. The subjects were grouped as short-time (<52w) or long-time (>52w) treatments. The median age, follow-up time, and injected doses were 73.5 (49–81) years, 21 (14–28) days, and 38 (8–47) units, respectively, with no significant difference between groups. The total complete blinks per minute before incobotulinumtoxina injection was 39 (23–64) which decreased to 18.5 (1–60) at follow-up (p = 0.004). The average change in complete blink rate was −67.4 ± 23.7% in long-time and −45.2 ± 31.2% in short-time groups (mean ± SD, p = 0.01). The total self-graded frequency of blinking and light-sensitivity decreased significantly at follow-up (p = 0.004, p = 0.047, respectively). Similar patterns of subject reported grades were seen in both groups.

Conclusion

Videotaping is a low-cost method for objective measurement of blink rate in blepharospasm patients after incobotulinumtoxina injection. There was a significant reduction in blink rate after incobotulinumtoxina injections with higher percentage of change in the long-time treatment group. Incobotulinumtoxina injection also significantly improves subjective photophobia.

KEYWORDS:

• Blepahrospasm
• botulinum toxin
• blinking
• photophobia
• dry eye

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/01676830.2022.2151628.

Additional information

Funding

Unrestricted departmental grant from Research to Prevent Blindness, New York, NY (SCP, MTY); The Hamill Foundation, Houston, TX (SCP); Sid W. Richardson Foundation, Ft Worth, TX (SCP).