Single eyelid - An upper eyelid with no visible crease
Double eyelid - An upper eyelid divided into a top and bottom portion by a visible crease; inborn or after surgery
Parallel crease - A crease that runs parallel to the eyelid edge along its full extent
Tapered crease - A crease that courses lower as it approaches the nasal (inner) side
Lateral flare - A gently upward flare as the crease approaches the temporal (outer) side
Inside fold - Same as a "tapered crease"
Inner double eyelid - Same as a "tapered crease"
Outer double eyelid - Same as a "parallel crease"
Pseudo-single eyelid - A crease, though present, is obscured by overhanging skin
Semilunar crease - A crease that arches higher over the eye while coursing lower at both the nasal (inner) and temporal (outer) corners. A more typical Occidental feature.
A crease may be further described as continuous, discontinuous, partial or incomplete, multiple, doubled, deep, shallow, asymmetric, one-sided, high, and/or low.
View examples of various creases
• Even within the Asian population, the incidence of natural crease formation varies. For instance, while approximately half of those of Chinese descent show at least some natural crease formation, only about one-third of those of Korean ancestry demonstrate this finding.
• The typical Asian crease is far different from the typical Occidental crease in terms of shape, height, and continuity. To speak of them both as one and the same is an over-simplification.
• It is not uncommon for half the siblings in a given Asian family to possess a defined double eyelid while the other half show little or no crease.
• It is common for natural creases to vary in terms of shape, height, or even presence between the two eyes of a single individual. About 10% of Asian people show a natural crease on only one of their two eyelids; more often than not, it occurs on the left side. More on crease asymmetry
• Fully single eyelids are more common in Asian men than women by a ratio of 3:2.
• On average, the eyelid opening (the space between the eyelids) is vertically higher in females but horizontally longer in males. This difference allows the crease to appear very slightly more arched in females and flatter in males.
• Just as some Asian people (although not many) possess naturally-occurring high semilunar creases, some Occidental people possess poorly-defined creases or no creases at all.
• Some Asian patients report a variable double eyelid that changes shape or even disappears entirely at different times throughout the day. More on crease variability
• Patients of mixed Asian and Occidental heritage demonstrate great variability in upper lid structure and crease appearance. For instance, some show extremely well-defined creases inherited from the Occidental parent that sit "hidden" beneath the thicker soft tissues inherited from the Asian parent. In such patients, cosmetic eye surgery may be untaken solely to better expose the crease.
• Many infants (Occidental and Asian) are born with a well-defined crease (or creases) in the lower eyelid. As they grow out of childhood, the crease tends to soften and then eventually disappears.
