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

Abstract Background To elucidate the changes in the tear film lipid layer and blink dynamics among patients with benign essential blepharospasm (BEB) after botulinum toxin A injection. 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/20s vs 2.43 ± 2.82 times/20s, 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. Conclusions Blink patterns measured by the interferometer in patients with BEB may overestimate complete blinking and may be misunderstood as a normal pattern. Although BoTA injection may relieve the symptoms of BEB, interpretation of the blink pattern and LLT should be carefully performed by ophthalmologists.