D2I2.
neurological

Blepharospasm

Blepharospasm is a disorder characterized by intermittent, involuntary spasms and contractions of the orbicularis oculi (eyelid) muscles around both eyes. These result in abnormal twitching or blinking, and in the extreme, sustained eyelid closure resulting in functional blindness.

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Plain-language summary adapted from Wikipedia. Not medical advice.