Why do some people have single eyelids and others have double eyelids? During human embryonic growth and development, the levator muscle mainly stops at the upper eyelid lid plate, but a part of the muscle fiber also stops at the deeper layer of the skin in front of the upper eyelid lid plate. Therefore, when you open your eyes, the local skin is lifted upward by this part of the muscle fibers, and a skin crease parallel to the eyelid margin appears above the eyelid margin, which is commonly known as double eyelid, blepharoplasty, or crease on the eyelid margin. If this part of the muscle fiber fails to develop, there is no crease when the eyes are open, which is often called monocleidomorphic eyelid, and the upper eyelid margin crease is missing. Oriental peoples are mostly mono-eyelids, and double eyelids for beauty. Generally speaking, where the eyelid is narrow and long, the upper eyelid is thin and tight, the eyelashes are long and dense, the eye sockets are deeper, and the bridge of the nose is higher than the single eye, the surgery is good, and the effect is obvious. On the contrary, the surgery is difficult and less effective in single eyes that have a short eye shape, a wide and short eyelid fissure, a hypertrophied upper eyelid, loose and sagging skin, or a protruding eyeball, a small eyeball, a shallow and flat eye socket, and a flat and collapsed nose. The skin fold on the eyelid margin can be surgically formed and is called double eyelid formation. The principle is to artificially form an adhesion between the deeper layers of the skin on the lid margin and the levator muscle. The operation is performed by making a skin incision parallel to the lid margin at a distance of 6-8 mm from the upper lid margin, cutting through the skin and orbicularis muscle layer, and then peeling the margins upward and downward, respectively. A portion of the orbicularis oculi muscle and the thickened subcutaneous fat tissue in front of the lid are thinned on the lower lip of the incision. The subcutaneous tissue at the lower edge of the incision is then secured with several stitches of fine silk suture between the lower edge of the incision and the upper edge of the lid, and the skin incision is finally closed. There is also a simpler method without a skin incision, the buried suture method. The double eyelid is formed by placing several mattress-type sutures with a silk thread across the entire eyelid at the upper edge of the lid. The principle is that the sutures cause adhesion between the skin and the muscle. Double eyelid surgery, the icing on the cake of cosmetic surgery, is very demanding and can only succeed, not fail. The success of the surgery depends mainly on the experience and skill of the surgeon (50%), the condition of the patient (30%), and the other 20% depends on the smoothness of the surgery, the healing ability of the incision, the occurrence of infections and other unpredictable factors. The most important thing is the problem of infection. If infection occurs after the operation, it will greatly affect the operation and even cause very serious consequences. Therefore, if there are folliculitis, active thrush, conjunctivitis, dacryocystitis, and severe trachoma and other infections on the face before surgery, it is not suitable for surgery for the time being, and it is necessary to wait for the cure of these diseases before arranging the surgery. During menstruation, the coagulation mechanism of women is disturbed, making it difficult to stop bleeding during surgery and easy to form hematoma after surgery. In addition, the resistance of the whole body is relatively reduced during menstruation, so the chance of wound infection increases. The day before the operation, it is best to wash your hair and take a shower, and change your clothes, in order to minimize the number of bacteria. Do not apply any cosmetics on your face on that day. Apply cold compresses for 4-6 hours after surgery, but be sure to keep the eye dressings intact and clean. Change the dressing regularly, pay attention to rest, take oral antibiotics and avoid stimulating food. Remove the stitches 6-7 days after surgery. Double eyelid surgery will be swollen, generally buried line method of swelling faster, 3-5 days to become more natural; incision method of swelling is slower, generally 8-10 days later began to become more natural, full recovery in some cases to 3 months later. Double eyelid surgery is done badly in all kinds of situations, some are good to repair, some are difficult to change. If the deformity is slight, if the double eyelid is narrow, if the fat is not removed during the surgery and if too much skin is removed, it is easier to modify it by using the buried threads; in the opposite case, it is difficult to correct it. Double eyelids cause serious deformity, mostly incision method, and it is difficult to correct. Another reason for the difficulty of repair is that multiple surgeries are unsuccessful. The more surgeries performed, the more difficult it is to correct. Many people are the first time the operation is not ideal, the patient went to the same operator or someone else to operate again, some may be fixed, some instead of getting worse and worse.