The precise design positioning of the double eyelid line is only a small step before surgery, because the design line is only an important factor in determining the width of the double eyelid. In clinical practice, such a situation often occurs. The line design of the eyes on both sides is basically the same, but the width of the lines after the operation is different. Sometimes the design lines on the two sides are obviously different, but the width of the double eyelid line is basically the same.  . Next, I will analyze the factors that determine the width of the double eyelids. The factors of the skin suture position are often written in textbooks 6-8mm to explain the design width range of the double eyelid. In fact, there are many factors that determine the width of the double eyelid, and it is not as simple as drawing a line. The pre-operative design line is to determine the location of the stretched skin, which is very close to the width of the double eyelid. Within a certain range, the higher the design position, the wider the double eyelid fold line.  . . 2. Factors of the levator muscle or meibomian suture position (including the levator muscle opening and closing factor) in addition to the design of the point of care, the muscle strength of the levator muscle also has a very important effect on the width of the double eyelid and folds.  . When the levator displacement is different, the width of the double eyelid line is also different. 1. When the normal muscle strength is open, a deep double eyelid fold is formed; when the levator muscle is weak, the mobility is poor, and the double eyelid line is shallow and wide. Patients with ptosis cannot form a deep double eyelid fold, which is the reason for the insufficient displacement. In other words, although the double eyelid fold is relatively wide, it appears to be inexplicable due to the low corneal exposure rate!  . Under normal muscle strength, even if the design line of the double eyelid is the same, if the position of the levator muscle or the eyelid plate is different, it may result in a different width of the double eyelid. three. The factor of skin peeling amount has a great influence on the width of double eyelid. Under the premise that the muscle strength is normal, the design line of the double eyelid is the same, and the position of the levator muscle or the eyelid plate is the same, the more loose the skin, the more the upper lip skin covers the lower lip skin after reflexion, the more the double eyelid fold line appears narrow. It can be seen that, within the limit and reasonable range, the greater the amount of peeling during double eyelid surgery, the wider the double eyelid width.  . Factors of the volume of the lower lip tissue . The height difference of the eye is limited by the fold line of the double eyelid, the relative height of the incision upper lip (the area between the double eyelid line and the eyebrows) and the lower lip (the area between the double eyelid line and the eyelashes) . Generally, the upper lip should be higher than the lower lip: the upper lip is slightly thicker, forming a sense of high-land fold, and the lower lip is easily folded into the upper lip, forming a natural and beautiful double eyelid appearance.  . Factors of tightness of incision adhesion The more firmly the double eyelid incision is adhered, the firmer the site of suture and attachment point is. Whether the thread is buried or the double eyelid is cut, the tissue of the adhesion site will gradually relax and shift downward. That is, the position of the fixed point of the double eyelid suture is also moved downward, and the width of the double eyelid will be narrowed. The double-embedded thread is most likely to loosen because the scar is lightly adhered and the nylon thread is cut.