• #1-4. Anatomical Concept of Asian Eyelid: Paradigm Shift to Evolution Eyelid Theory


    If we agree to the existence of an anatomical structure unique to Asians, we may now find ourselves in a more fundamental dilemma; Can an anatomical difference exist between Asian and Caucasian eyelids? Biologist Ernst Mayr defined “species” as following; “species are groups of interbreeding natural populations that are reproductively isolated from other such group.” As today’s general scientific concept sees all humans belonging to the single race of Homo sapiens, the postulation that there are fundamental anatomical differences between humans cannot be accepted. Biological racism was still holding up in the early 20th century when it was found that the Mongolian spot, which was previously thought to appear in Asians only, appears in all races.


    Currently, no anatomy textbooks discuss anatomical differences between races. The epicanthus hypothesis which posits that epicanthus is a type of developmental malformation only affecting Asians has numerous errors. Today, the jury is still out on the etiology of epicanthus or medical definition of it. The medical definition of epicanthus is vague at best. Considering that the epicanthus appears in a wide variety in most Asians, classifying it as a congenital malformation just is not viable.


    In 2003, the Human Genome Project revealed that the DNA of all humans on Earth is 99% identical and genetic and biological evidence was found for all humans belonging to the single race of homo sapiens. Considering this, it would be illogical and contradictory to this discovery to believe that a unique anatomical eyelid structure exists in Asians only. However, the epicanthus concept is still at the center of the dominant medical paradigm regarding the Asian eyelid anatomy.


    Epicanthus needs to be re-examined against recent knowledge of anthropology, evolutionary biology, and medicine. This is along the same line of examining the reason for the lack of palpebral fold in Asians. The palpebral fold can develop at various stages of life including at birth. This suggests latency of the anatomical structure. From the perspective of evolutionary biology which forms the basis of modern biology, we can ask “is it possible that the palpebral fold which is even found in primates, is lacking only in Asians?” Then, it becomes evident that we need to examine whether there are fallacies in two stereotypes that form the basis of today’s anatomical knowledge of the Asian eyelid.


    There have been many papers on how the Asian eyelid differs from the Caucasian eyelid and surgical techniques of Asian blepharoplasty. However, none have tried to verify the definition of epicanthus and palpebral fold. Even if one assumes that it is biologically possible for the lack of palpebral fold and presence of epicanthus to only affect Asians, no paper or textbook have suggested a scientifically acceptable explanation of the cause other than the group developmental arrest theory (Hemmungsbiludung).


    For us to establish correct surgical techniques of the Asian eyelid, we need to first clarify basic anatomical concepts that are currently at controversy. We need to review previous literature to examine the history of currently accepted anatomical concepts of epicanthus and palpebral fold. We can then set the right direction for research on anatomy of Asian eyelid and Asian blepharoplasty. To understand the controversies surrounding the anatomy of Asian eyelid, we need to review the 19th century European medicine. Our discussion will start with the 19th century Göttingen, a college town in Germany, to include scholars in France and other European countries, the US, Canada, Japan and China over the next 200 years.


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    p.s. In history, the epicanthus has been defined and translated in various ways in different countries. Papers on the anatomical structure of the Asian medial eye included similar terms such as epicanthis aquisitus, plica palpebronasalis, Mongolenfalte, Mongolian fold, bride Mongolique, plica marginalis, hemiepicanthus, and Mongolian eye, etc. And the academic definitions have also varied depending on the country, era and scholar. In Korea, the official translation of “epicanthus” was revised to “medial canthus fold” from “medial eye excess skin” and the general public is also using the term epicanthus. There is not only academic controversy over the term of epicanthus but also confusion over various translations as well as wide-spread misperception. In the west, the supratarsal crease or palpebral fold are used to refer to what is known as the double eyelid in Asia.


    In German, ‘obere lidfalte’ has the same meaning. The term double eyelid is distinguished from single eyelid and refers to the eyelid with a palpebral fold, however these terms do not exist in the West where “eyelid” (augenlid) always means an eyelid with a palpebral fold. The term “double eyelid” (doppel augenlid) is starting to be used in the West recently but mostly among Asians living in the Western countries. In the 19th century German literature, there are no terms referring to palpebral fold at all. To minimize confusion in the following articles, I will include the English, German and Latin terms with similar meaning to epicanthus  and use palpebral fold to refer to the double eyelid. Also, various English and German terms referring to the palpebral fold will be left in the original language followed by “(palpebral fold).” 


    -To be continued

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