Effects of botulinum toxin on tear film and corneal epithelial remodeling in patients with essential blepharospasm.

PURPOSE: Benign essential blepharospasm (BEB) is a focal dystonia characterized by involuntary eyelid contractions that can disrupt tear film stability and corneal morphology. Botulinum toxin type A (BTX-A) injection is the standard treatment, yet its impact on ocular surface health and corneal epithelial structure remains unclear. This study aimed to assess the effects of periocular BTX-A on tear film parameters and corneal epithelial remodeling using anterior segment optical coherence tomography (AS-OCT).

METHODS

This retrospective, single-center study included 35 eyes of 35 BEB patients treated with standardized periocular BTX-A injection (total dose ∼12.5 units). Ocular surface parameters Ocular Surface Disease Index (OSDI), tear breakup time (TBUT), Schirmer test, tear meniscus height (TMH), and meibomian gland dropout were evaluated at baseline and 3 months post-treatment. Corneal epithelial maps obtained via AS-OCT provided central, superior, and inferior epithelial thicknesses and irregularity indices. Corneal power and astigmatism were analyzed by topography. Pre- and post-treatment values were compared using paired tests.

RESULTS

At 3 months, blepharospasm severity and OSDI scores improved significantly (P<0.001). TBUT and TMH increased (P<0.001), while Schirmer test and gland dropout were unchanged. Superior epithelial thickness increased and irregularity indices decreased (P<0.001), indicating smoother remodeling. Corneal power and astigmatism decreased significantly (P<0.001), consistent with corneal flattening. No adverse effects were observed. Improvements correlated with reduced spasm severity.

CONCLUSION

BTX-A injection in BEB patients alleviates spasms and enhances tear film stability and epithelial regularity. The treatment is safe and well tolerated, offering additional ocular surface benefits beyond motor symptom control.