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.
7 Causes for Eye Twitching. Fatigue. Another reason for twitching eyes may be a lack of sleep or fatigue resulting from it. Fatigue resulting from physical exertion or inadequate sleep can both cause the eye to twitch. Just as fatigue has the potential to affect other muscles in the body, it can do the same to muscles of the eyelid as well.