[Botulinum toxin type A (BOTOX) for treatment of blepharospasm: an open label, dose-response study].

The clinical effect of Botulinum Toxin Type A (BOTOX) were studied in patients with blepharospasm. Clinical symptoms were evaluated with Jankovic's rating scale, widely used for blepharospasm. To see dose response, eyelid muscle force of the patients was measured with a device recently developed for measurement of eyelid muscle force. The results showed significant improvement (p = 0.0000) on Jankovic's rating scale in all patient groups after effective dose injections of 0.5, 1.25, and 2.5 U/site. Particularly the number of patients with marked improvement (decrease of six points or more in total score on Jankovic's rating scale) increased with higher dose injections. The eyelid muscle force also decreased by 33.2 +/- 28.1%, 41.7 +/- 25.1%, and 69.6 +/- 5.0% in patients groups after effective dose injections of 0.5, 1.25, and 2.5 U/site, respectively. The decrease of the eyelid muscle force showed significant dose response (p = 0.0254). Mean duration of effect was 12.9 weeks in patients after effective dose injections of 1.25 U/site, which was significantly longer (p = 0.0205) than that of 9.6 weeks in patients after effective dose injections of 0.5 U/site. No severe adverse effects were observed. We concluded that BOTOX injections of 1.25 U/site or more are a safe and effective treatment of blepharospasm.