Corneal Topographic Changes after Botulinum Toxin-A Injection in Patients with Essential Blepharospasm

Purpose: To compare the corneal topographic change before and after botulinum toxin A injection in patients with essential blepharospasm.Methods: From September 2015 to December 2020, we enrolled total 20 patients, 40 eyes diagnosed with essential blepharospasm. We estimated the corneal refractive power and astigmatism before and after Nabota^® (Daewoong Co. Ltd, Seoul, Korea) botulinum toxin injection at 1 and 3 months using iTrace^® Topography (Software version 4.2.1., Tracey technology Inc., Houston, TX, USA). Corneal refractive power was analyzed in superior, inferior, nasal and temporal location at 1 mm, 3 mm zone. Also, steep and flat keratometry, astigmatism was measured by topography.Results: Corneal refractive power showed significant difference in superior and inferior location of 1 mm zone at 1 month after botulinum toxin injection (p = 0.038, p = 0.042). There was no significant difference in all four locations of 3 mm zone. At 1 month after toxin injection, steep keratometry was only significant reduced (p = 0.046) and with-the-rule astigmatism was shifted to against-the-rule astigmatism. At 3 months after toxin injection, keratometry and astigmatism was resolved to before toxin injection.Conclusions: At 1 month after Nabota^® (Daewoong Co. Ltd) botulinum toxin injection, corneal refractive power at vertical axis was flattened and steep keratometry was significantly reduced. At 3 months after toxin injection, corneal topographic change was changed to before toxin injection.