My eye-doctor told me he thought it would be caused, many times, by caffine. However, It's been a while for me from when I last had eyelid quiver and still have drank alot of coffee lately. So, I don't see the connection. I think stress and possibly a lack of vitamins in the diet could also be a cause. I've ramped up vitamins this year and many physical ailments have stopped. Also have lost 40-lbs as well.