Primary blepharospasm is an adult-onset focal dystonia characterised by 
involuntary contractions of the orbicularis oculi muscles. Patients may have 
various types of movements arising from the different parts of the orbicularis 
oculi muscle. These include typical blepharospasm associated with Charcot's 
sign, pretarsal blepharospasm and flickering of the eyelids. Primary 
blepharospasm may be associated with so-called apraxia of eyelid opening as well 
as dystonia in the lower face, jaw or cervical muscles. Unless there are 
clinical clues to a symptomatic cause, adults presenting with blepharospasm do 
not require extensive aetiological investigation because the condition is rarely 
due to an identifiable condition. As the aetiology of primary blepharospasm is 
largely unknown, therapeutic approaches are symptomatic, with type A botulinum 
toxin being the treatment of choice.