Epicanthic fold Epicanthic fold The epicanthic fold is the skin fold of the upper eyelid, covering the inner corner (medial canthus) of the eye. Various factors influence whether epicanthic folds form, including ancestry, age, and certain medical conditions. The highest frequency of occurrence of epicanthic folds are found in: East Asians, Southeast Asians, Central Asians, North Asians, some South Asians, Polynesians, Micronesians, Indigenous Americans (as well as Mestizos), the Khoisan, Malagasy. In some of these populations the trait is almost universal. Epicanthic folds occur, but at considerably lower frequency, in: Europeans (e.g., Scandinavians, English, Irish, Hungarians, Russians, Poles, Lithuanians, Finns, Estonians and
Epicanthic fold Samis), Nilotes and Amazigh people. The degree of development of the fold between individuals varies greatly and its presence or absence is often subjective, also its frequency varies clinally across Eurasia. Its use, therefore, as a phenotypic marker to define biological populations is debatable. The epicanthic fold is often associated with greater levels of fat deposition around the eyeball, a feature most accentuated in native North Siberian, Aleut and Inuit populations. The adipose tissue is thought to provide greater insulation for the eye and sinuses from the effects of cold, especially from freezing winds, and to represent an adaptation to