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.
Nevertheless, eyelid twitches may be caused or made worse by: 1  dizziness. 2  eye irritation. 3  eyelid strain. 4  fatigue. lack of sleep.  physical 1  exertion. medication side effects. 2  stress. use of alcohol, tobacco, or caffeine.