Are you talking about the upper or lower eyelids? There are a few conditions which may lead to what people call "saggy" or "droopy" eyelids, depending if we are talking about the upper or lower eyelids 1. Eyelid ptosis [droop] 2. Excess eyelid skin [dermatochalasis] 3. Heavy or low eyebrows 4. Prolapsed eyelid fat. Unless you post a photo, its hard for us to tell you what might apply to you.
Pictures would be helpful to give you better advice, but in general, there are two types of surgery that can help with saggy upper eyelids. These would be surgery to raise the eyebrows and surgery to remove some of the excess skin of the upper eyelid. Without seeing you or pictures of you, it's impossible to know if you would be a candidate for either procedure.