Walsh & Hoyt: Abnormalities of Eyelid Closure

As with eyelid opening, abnormalities of eyelid closure may occur from disorders involving any part of the pathway for contracture of the orbicularis oculi, from the cerebral cortex to the muscle itself. Such disorders may be congenital or acquired and may be caused by either hypofunction or hyperfunction of the orbicularis muscle and, to a lesser extent, by the muscles that assist the orbicularis in eyelid closure (i.e., the frontalis, procerus, and corrugator superciliaris)