Blink index as a response predictor of blepharospasm to botulinum neurotoxin‐A treatment

Abstract

Purpose:We investigated the blink profiles and blink index using ocular surface interferometer in the patients with blepharospasm (BSP) and identified points to consider predictive factor after BSP treatment. Methods:In total, 117 eyelids of 59 elderly patients and 20 eyelids of 10 age-matched control group were studied. All BSP patients applied botulinum toxin-A (BoNT-A) injection for treatment of BSP. An ocular surface interferometer (LipiView; TearScience, Morrisville, NC, USA) was used to measure blink profile and blink index; total and incomplete blinks/20 s, and the partial blink ratio (PBR). Eyelid blink time (including lid closing time, closure time, lid opening time), interblink times (IBT), closing speeds (OS), and opening speeds (OS) were analyzed using 600 blinks recorded over 20 s.Results: Total blink rate was significantly higher in BSP patients compared to the age-matched control group (p = .029) but other time-related and speed-related index including interpalpebral fissure, PBR, blink time, closure time (CT), interblink time, CS, and OS were not significantly different. In the responder of BSP patients, the average age was higher, CT was shorter, CS was faster than nonresponder (age; p = .016, CT; p < .001, CS; p = .042). Conclusion:The blink index by analyzing the blink profile using ocular surface interferometer, and this blink index may be used as a predictive factor for evaluating the clinical response after BoNT-A injection in blepharospasm patients. K E Y W O R D Sblepharospasm, blink index, blink profile, botulinum neurotoxin-A INTRODUCTIONBlepharospasm (BSP) is the focal dystonia involving periocular muscles and result in involuntary and abnormal eyelid movement. BSP patients have increased blink rate at rest and during conversation compared to healthy people (Bentivoglio et al., 2006). In addition, increased blink rate may precede BSP that the results of more than 5 years of follow-up on the patients with increased blinkingThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Clinical implications of genetic polymorphisms in blepharospasm

“…Comparing the two responder groups to BoNT-A injection, the previous study reported that the poor responders exhibited a different blink profile such as increased lid closure time and decreased closing speed, including apraxia of eyelid opening ( 31 ). Therefore, a more detailed classification of BSP is required, along with a revised approach to treatment selection.…”

“…Good responders were patients who improved to 0 or 1 on the rating scale and maintained the same injection dose at the next injection as that applied at the initial injection. Poor responders were patients who exhibited >2 points on the rating scale at the initial injection, along with an increase of 50% in the BoNT-A dose at the next injection ( 31 ).…”

Blinking Parameters Do Not Normalize After Botulinum Toxin Therapy in Blepharospasm and Hemifacial Spasm Patients

“…They also observed reduced amplitude and peak velocity of blinks on the treated side. Jang et al 18 retrospectively analyzed 20-second videos using LipiView Interferometer (TearScience, Morrisville, NC) in BSP patients. In contrast to our results, they did not find significant differences between BSP and control patients or differences in closing velocity in BSP patients after BoNT-A injections.…”

Eye-Closure Rate Modulation in Blepharospasm

“…The eye closure rate which was measured in this study is different from the blink rate because we included any type of eye closure in the measurements, including blinks and spasms. Increased blink rate alone has been used as a simple measure to assess response to treatment in blepharospasm [ 18 ] but it has low specificity and sensitivity for the diagnosis of BSP [ 9 ] and its pathophysiology may be different than orbicularis oculi muscle spasms [ 19 ]. Another limitation is the relatively low number of participants which may not be adequate for such a high number of comparisons.…”