A blepharospasm is the uncontrolled and repetitive muscle spasm of the circular muscle around the eye or eyelid, causing the abnormal positioning and movement of the eye (dystonia).
According to the Institute of Ocular Microsurgery in Spain, this movement can occur along with other movements of the neck, head or mouth which only go away with sleep. (See also: Protect Your Eyes with Proper Eye Care).
Some of the causes of this condition are a neurological functional disturbance in the central nervous system, side-effects from certain drugs and a lack of lubrication on the ocular surface. According to the webpage MedlinePlus, fasciculations (repetitive and uncontrolled repetitive spasms of the eyelid), sensitivity to light and blurry vision are some of the most common symptoms of this spasm.
While this condition cannot be prevented and generally goes away with time, it is important to see a specialist if it continues, as it can be a related to ophthalmological or neurological problems. Some of the measures that can be taken to help it go away include getting more sleep, drinking less caffeine and keeping the eyes lubricated with eyedrops. Related article: Dry eye syndrome (article in Spanish).