Epicanthic fold: A vertical skin fold at the inner corner of the eye.

The epicanthic fold is a vertical skin fold covering the inner eye corner. It arises from muscle structure and varies by ancestry, age, and environment. Found globally, it is common in East Asian and Indigenous American populations.

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Caused by orbicularis oculi muscle structure
Common in East Asian and Indigenous American groups
Distinct from monolids which lack eyelid creases
May protect eyes from cold or UV light
Visible in young children before nose develops

What it is

An epicanthic fold is a vertical layer of skin situated on either side of the nose. It sometimes covers the inner corner of the eye, known as the medial canthus. This feature varies in appearance, with some individuals showing partial or slight folds. It is distinct from a monolid, which lacks an upper eyelid crease. The fold results from the structure of the orbicularis oculi muscle near the eye. Recognition depends on observing the skin curve over the inner eye area.

History and origin

The term derives from Greek roots meaning above the eye corner. Scientists have long studied its distribution across global populations. Early theories linked it strictly to cold climates in Asia. Later research noted its presence in African and European groups. This broadened understanding of its origins. Classification systems now identify four types based on where the fold begins and ends. These include variations starting at the brow or lower lid.

What it means

This trait is a normal human variation found in many communities. It is not linked to character or intelligence. In some regions, such as East Asia, it is extremely common. Among other groups, it appears less frequently. Its presence has been subjectively interpreted by observers based on local norms. It serves as a phenotypic marker but does not define biological race. Respect for this natural diversity is essential in any discussion of facial features.

The science

The primary cause is hypertrophy of the preseptal orbicularis oculi muscle. Fat deposition around the eyeball often accompanies the fold. Evolutionary theories suggest it insulates the eye from cold winds or snow blindness. Other hypotheses propose protection from ultraviolet light in high-altitude or desert areas. Genetic factors, including pleiotropic genes, likely control its development. It appears in foetuses and young children before the nose bridge fully forms.

A drawing made by EveryFaceShape from what this page says. It is a diagram, not a picture of the real face guide.

In culture

The fold is prevalent among East Asians, Southeast Asians, and Indigenous peoples of the Americas. It is also found in some African populations, such as the Khoisan. In Europe, it occurs among Scandinavians and Baltic peoples. Medical literature notes its association with certain congenital conditions. However, it is primarily a natural anatomical feature. Misclassification as a monolid is common, though the two are structurally different.

Epicanthic crease circled.. Photo: RebeccaLi292, CC0, via Wikimedia Commons

Questions people ask about Epicanthic fold

What causes an epicanthic fold?

It is primarily caused by the hypertrophy of the preseptal portion of the orbicularis oculi muscle. Ancestry, age, and genetic factors also influence its formation. It is a natural anatomical variation.

Is an epicanthic fold the same as a monolid?

No. Monolids lack an upper eyelid crease. Epicanthic folds involve excess skin curving over the inner eye corner. A person can have both, neither, or one without the other.

Which populations commonly have this feature?

It is highly frequent in East Asians, Southeast Asians, Central Asians, and Indigenous peoples of the Americas. It also appears in some African, European, and South Asian groups.

Good reading and sources

Q&A (Published 1985)The New York Times, Article

Where this page comes from

The facts on this page come from the Wikipedia article "Epicanthic fold", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). EveryFaceShape rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.

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Epicanthic fold