Blepharospasm is the involuntary contraction of the muscles of eyelid closure. It typically involves all four eyelids and can affect visual function. It usually disappears with sleep. Blepharospasm can be treated with botulinum toxin, which improves the involuntary contraction of eyelid closure. This has been performed successfully for over 25 years. It is the mainstay of treatment for blepharospasm. Treatment typically lasts for 3 months at which time, repeat botulinum toxin administration is typically necessary.