Tear film lipid layer thickness and blink dynamics in patients with blepharospasm

Background: This study investigates the effect of botulinum toxin A on lipid layer thickness (LLT) and blink dynamics in patients with benign essential blepharospasm (BEB) compared to dry eye disease (DED) patients. Methods: We reviewed the medical records of patients with dry eye disease (DED) and BEB treated with botulinum toxin A (BoT A) injections. Data on demographics, lipid layer thickness (LLT), meiboscore, and blink dynamics measured using a LipiView II interferometer before and 2 months after BoT A were collected. Results: Each 28 eyes from 28 patients with BEB and age- and sex-matched patients with DED were included. When comparing blink dynamics, complete blink rate was significantly higher in the pre-injection BEB group compared to the DED group (5.25 ± 4.32 times/20 s vs. 2.43 ± 2.82 times/20 s, p = 0.0055). In tear film lipid profiles analyzed in BEB patients at pre-injection and 2-month follow-up after injection, average LLT significantly increased after injection (72.4 ± 22.7 nm to 83.0 ± 22.2 nm, p = 0.0215). Diabetes and young age were associated factors influencing the LLT increase. Significant increase in LLT was observed post-injection, with specific demographic factors, including diabetes and age, associated with this improvement. Additionally, blink dynamics showed a decrease in complete blink rate post-injection. Conclusions: These findings suggest that BoT-A may alleviate BEB symptoms, but ophthalmologists should carefully interpret LLT and blink patterns in BEB patients due to potential overestimations of blink efficacy by the interferometer.