How to treat a permanent droopy eyelid?

It depends: Depending on the cause of the droopy eyelid, surgery can be used to lift it. Most commonly it is due to a stretched out tendon attaching the eyelid lifting muscle to the end of the eyelid, which is corrected by tightening this attachment. In children, it is often due to a poorly developed muscle, which can be suspended with artificial material or tucked through an internal eyelid surgery.

Droopy eyelid repair: The type of procedure depends on the cause of the droopy eyelid. If the eyelid is droopy from stretching of the eyelid lifting muscle, then a levator advancement or a mueller muscle resection may be performed. If the eyelid is droopy from weakness in the eyelid lifting muscle, then a frontalis sling surgery may help.

Many ways: It depends how many millimeters of lift you need to match with the normal side. It can range from simple muscle tightening to placing a sling and get help from your forehead muscle.

Depends on the cause: This is known as "ptosis" of the eyelid, and to fix it, some form of "ptosis repair" is performed. In adults, the most common cause of eyelid ptosis is related to the tendon that lifts the eyelid being stretched - so the repair involves shortening the tendon to the correct length.

Droopy eyelid: There are several causes of a droopy eyelid. Your best bet would be to have your eyes evaluated by a board certified facial plastic surgeon.