The “medial canthus” is a half-moon fold of skin that covers the vertical aspect of the medial canthus and is often formed from the upper lid to the medial canthus. The canthus is closely related to ethnic differences. It is most commonly found in Mongolian populations in Central, North, and East Asia, and is therefore also known as the “Mongolian fold. The medial canthus is a vertical skin fold, which naturally creates skin tension in the vertical direction, whereas the fold formed by the blepharoplasty is horizontal, and when the eyes are opened to form the blepharoplasty fold, the tension is also in the vertical direction. Therefore, the inner canthus is shaped on top of the redundant skin, which often does not form the eyelid due to tension. If the eyelid is forcibly formed, the tension will be too high, causing a heavy feeling when the eyes are opened and long-term fatigue, as well as pseudo-hyperlidosis, and a more obvious scar will form due to the tension. If the eyelid line is formed under the redundant skin, the inner part of the eyelid crease cannot be seen because of the redundant skin, resulting in a so-called “half double” eyelid, which is not beautiful. Therefore, when performing blepharoplasty, in the case of a heavy medial canthus, the redundant skin should be corrected at the same time as the blepharoplasty so that there is a good blepharoplasty effect and a widening of the lid fissure.