Blepharospasm is abnormal twitching, fluttering or spasmodic eyelid closure. It is caused by spasms of the orbicularis oculi muscle, the muscle which normally makes you blink. Most people blink 10 to 20 times per minute, a little less when concentrating on reading or a computer screen. An increase in blink frequency and strength is called blepharospasm.
This is a companion discussion topic for the original article at https://patient.info/bones-joints-muscles/hemifacial-spasm-leaflet/blepharospasm