The main difference between monocleid and endocleid is that the formation mechanism is different and the appearance is different. Monocleid eyelids have no folds for a long time, which means that during congenital development, the fibers of the levator muscle do not enter the skin of the upper eyelid, resulting in the contraction of the levator muscle will not pull the skin of the upper eyelid to move together, and will not form the double eyelid folds. People with single eyelids can change the shape of their eyelids through threading and total eyelid incision, resulting in the appearance of double eyelids. The double eyelid is a small double eyelid hidden under the appearance of a single eyelid. This is due to the fact that some of the muscle fibers of the levator muscle enter the skin layer of the upper eyelid, and when the muscle contracts, it pulls some of the skin of the upper eyelid upward, forming a small crease. It is recommended that patients with eyelid abnormalities seek medical attention to evaluate their condition and follow their doctor’s instructions.