The Role of Botulinum Toxin in Dry Eye Disease and Meibomian Gland Dysfunction Associated with Hemifacial Spasm.

[OBJECTIVES] To investigate the signs and symptoms of dry eye disease (DED) in patients with hemifacial spasm (HFS) through the evaluation of ocular surface measurements and meibomian gland function, and to assess the effects of botulinum toxin type A (BTX-A) injection on ocular surface health.

[METHODS] This prospective study included patients with unilateral HFS who underwent BTX-A injection as treatment. Eyes on the same side as the spasm were defined as the HFS group, whereas the contralateral, unaffected eyes were used as controls. Ocular surface assessments included the ocular surface disease ındex (OSDI) score, Schirmer's I test, tear break-up time (TBUT), corneal surface staining, eyelid margin abnormalities, and meibomian gland function. All evaluations were repeated at 1, 3, and 6 months following BTX-A injection.

[RESULTS] Compared to the control group, the HFS group demonstrated significantly higher OSDI scores, corneal surface staining, eyelid margin abnormalities, meibomian gland expression scores, meibography scores, and meibomian gland loss, whereas TBUT and Schirmer's I test values were significantly lower (p<0.05). A significant correlation was observed between the severity of HFS and ocular surface dysfunction, including meibomian gland dysfunction (MGD) (p<0.05). Following BTX-A injection, ocular surface parameters showed significant improvement at 1 month (p<0.05) and 3 months (p<0.05) compared to pre-injection values.

[CONCLUSION] We found an association between HFS and DED, which was correlated with the severity of HFS. In addition, BTX-A injection led to a temporary improvement in dry eye signs and symptoms, including MGD.