According to statistics, children born to parents with double eyelids and single eyelids may have double eyelids or single eyelids; children born to parents with double eyelids mostly have double eyelids; children born to parents with single eyelids mostly have single eyelids. Human survival conditions affect the shape of the eyelids There are more people with double eyelids in the south than in the north, which may be the result of long-term adaptation of human anatomy to the natural environment. In northerners, such as Mongolians, the eyes need to open and close in time to resist harmful stimuli, and this has led to a long evolutionary process that has resulted in relatively thick orbicularis oculi and small eye fissures, resulting in more monocular eyelids. In addition, the width of the Chinese heavy eyelid is significantly different from other countries, mostly between 6 and 8 mm. Acquired diseases can affect the shape of the upper eyelid. For example, when a boil on the upper eyelid is mishandled, or when a scar deformity is caused by having an abscess that has been operated on; burns, scalds, or corrosion can cause eyelid injury or deformation; in older people, the eyelids gradually loosen due to disease or aging, and multiple folds can appear in those with double eyelids or become double eyelids in those with single eyelids. The traditional eye aesthetic standards for oriental people are: double eyelids are prettier than single eyelids, large eye fissures are prettier than small eye fissures; sclera and iris are prettier if they are black and white than if they are not; the spacing between the eyes is moderate than wide or narrow; the horizontal axis of the eyes is slightly slanted upward, and long and dense eyelashes are prettier than those with a downward axis and short and sparse eyelashes. The best distance between the eyes is equal to the width of one eye; the best distance between the upper eyelid margin and the eyebrows is the height of the eyebrows and the upper eyelid margin; single eyelids are in harmony with other organs of the face Those with aesthetic appeal are also considered to have a more desirable eye shape. The distance between the two inner corners of the eyes should be 1/3 of the distance between the two outer corners of the eyes; the distance between the two outer corners of the eyes and the lateral edge of the face should be 19 to 24 mm; the distance between the upper lid margin and the eyebrows should be about 10 mm; the upper and lower lid fissures should be 10 to 12.5 mm in diameter, and the left and right lid fissures should be 30 to 34 mm in diameter; the corneal exposure rate should be 80%, and the corneal diameter should be 12 to 13.5 mm. The corneal diameter is 12 to 13.6 mm; the lid fissure angle is 48° to 55° at the inner corner of the eye and 60° to 70° at the outer corner of the eye.