I have had a drooping eyelid for some time and also wear glasses, but recently I have developed an eyelid twitch. What could cause this, and how can it be treated?

Those annoying twitches are caused by a nerve. I get them also, but they usually only last a few minutes, and go away by themselves. My eye doctor said to use hot packs on them, but I just take a warm washcloth. They are not serious, and will not harm your eye. The drooping lid might require some cosmetic surgery. Bring it to your eye doctor's attention.