1 Touch Response: The keys on a digital piano or keyboard can be weighted (similar to those of a traditional piano), touch sensitive (unweighted but still sound loud when struck hard), or neither.
In very rare instances, eyelid twitching can indicate a more serious condition, like the beginning stages of multiple sclerosis or a lesion on the brain stem. Those conditions typically begin with a host of symptoms, and in this circumstance the eyelid twitch soon moves to the facial muscles, as well.
Eyelid twitching may be triggered by: 1  Alcohol intake. 2  Bright light. 3  Caffeine excess. 4  Fatigue. 5  Irritation of the eye surface or inner eyelids. 6  Physical exertion. 7  Smoking. 8  Stress. 9  Wind.