Epicanthal fold
From Wikipedia, the free encyclopedia
An epicanthal fold, epicanthic fold, or epicanthus is a skin fold of the upper eyelid (from the nose to the inner side of the eyebrow) covering the inner corner (medial canthus) of the human eye.
The term "epicanthal fold" refers to a visually categorized feature; however the underlying physiological reason and purpose for its presence in any given individual may be entirely different.
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[edit] In children
All humans initially develop epicanthal folds in the womb. Some children lose them by birth, but epicanthal folds may also be seen in young children of any ethnicity before the bridge of the nose begins to elevate.
[edit] Inherited
The maintenance of the epicanthic fold into adulthood in many populations is believed to have evolved as a defense against both the extreme cold as well as the extreme light[citation needed] that occurs in the Eurasian arctic and north. It has also been suggested that the fold provides some protection against dust[citation needed] in areas of desert such as that found in the deserts of northern China and Mongolia as well as parts of Africa.
There is a wide distribution of the epicanthic fold across the world. It is found in significant numbers amongst Native Americans, the Khoisan of Southern Africa, many Central Asians and some people of Sami origin, though a great majority of Samis does not have it. The presence of epicanthal folds is common in people of many, though not all, groups of East Asian and Southeast Asian descent. It also occurs sometimes on people of South Asian descent, especially Bengalis. Due to classic genetics children of a parent with a pronounced epicanthal fold and one without an epicanthal fold will have varying degrees of epicanthal folds as a result.
In Asian ethnicities, the presence of an epicanthal fold is associated with the lack of an upper eyelid crease, commonly termed "single eyelids" as opposed to "double eyelids". The two features are distinct; a person may have both epicanthal fold and upper eyelid crease, one and not the other, or neither.
[edit] Pathological
In persons whose ancestry would make epicanthal folds otherwise unlikely to occur, the presence of the feature can be indicative of chromosomal disorders such as Down syndrome (Trisomy 21) or Cri du Chat syndrome.
[edit] Surgical alteration
The procedure of reducing or removing epicanthal folds is epicanthoplasty.
[edit] Pejorative terms
As might be expected of an inherited feature of such appearance there are many associated descriptions used among various groups. In some parts of the English speaking world, the term "slanted eyes" is still in colloquial use, though it is widely considered offensive in urban areas. The term is technically incorrect; most individuals possessing epicanthic folds actually have eyes which appear aligned more horizontally than those who do not.[citation needed] The term is also considered offensive [1] and, along with other terms with racially motivated undertones, is declining in usage.[citation needed] Another pejorative term is "Slit eyes". This probably originates in relation to individuals who have "single eyelids" as the roundness of the eye is less obvious.
