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 An eye twitch is an involuntary spasm of the eyelid muscle that often happens in the upper lid. The sensation, for most individuals, is that of a gentle tug on the eyelid but some others may experience the twitching to be more of a strong spasm forcing the eye to be completely closed before opening it again.