Over time, the eyebrow loses its natural ligamentous support to the forehead and orbital rim (the eyebrow bone). As this support weakens, the eyebrow can fall (eyebrow ptosis), which can cause the eyelids to get droopy. When the eyelids get droopy, the forehead muscles contract to try to raise the brows and lids. Then, the forehead accumulates furrows and wrinkles from constant effort to keep the eyes more open.
Forehead or eyebrow lifting procedures aim to improve the eyebrow support, preventing the eyebrow from falling too low and causing droopy lids. Forehead lifting surgery is also sometimes performed for cosmetic reasons.