Deep under the skin of the human eyelid is a small, thin muscle known medically as the levator palpebrae. When it contracts, the upper eyelid lifts and the eye opens. When the eye is opened, the pull of the muscle fibers creates a wrinkle in the skin of the upper eyelid, which is called a double eyelid. There are some yellow people who do not have this muscle fiber under the upper eyelid skin, and these people have single eyelids. There are many ways to turn single eyelids into double eyelids. Blepharoplasty is the surgical method of forming double eyelids. Blepharoplasty is divided into two types: incision and suturing, both of which are based on the same basic principle of causing trauma between the upper eyelid skin and the lid plate or the levator aponeurosis to form scar adhesions, and if the scar adhesions are not strong, the double eyelids will disappear. Not all people with single eyelids are suitable for double eyelid surgery, and not all people who have had double eyelid surgery will be satisfied with it. The constraints include: 1. the design of the surgical incision. It is directly related to the surgical result. The design of the incision position is closely related to the patient’s requirements and the aesthetics of the physician, so the patient should have a serious discussion with the plastic surgeon before surgery to avoid disagreement after surgery due to different perceptions of the effect. 2. The patient’s own conditions. Some patients wish to have blepharoplasty, but their own conditions are not good enough and the results are poorer. For example, patients with more anteriorly protruding eyes may appear fazed and have a more serious expression after blepharoplasty because of the change in their appearance. Other factors in this category include patients with small eyes, those with a close distance between the eyes, those with too much fat between the eyebrows and the upper lid margin, and those with very loose upper lid skin. These factors should all be carefully considered before surgery. 3. Patients with scarring should not undergo this surgery, otherwise it will cause postoperative scar growth and destroy the cosmetic results. 4, facial infection, such as folliculitis, acne, etc., should be cured after these diseases before considering facial cosmetic surgery. 5. Those who have conjunctivitis in both eyes should be treated for the eye disease first and then have blepharoplasty after it is cured. 6. Women should not have surgery during their menstrual period because of the heavy bleeding during surgery and the long and reactive local swelling after surgery, so it is best to schedule the surgery for three or four days after the menstrual period clears. Finally, there is another important factor, which is the quality of the plastic surgeon. A good plastic surgeon should have a deep understanding of surgery, be highly trained, have good surgical skills and be dedicated to the patient’s medical ethics, otherwise, even the smallest surgery may cause harm to the patient.