The Asian periocular anatomy is very different from that of a Caucasian or African American on many levels. Firstly, the shape of the orbital bones makes a tremendous impact on the 3D shape and angle of the eyelids. In an Asian, the lateral orbital rim, or the rim of bone that can be felt at the outer corner of the eye, sits on average 3mm more anterior than in Caucasians, and 5mm more anterior than in African Americans (Migliori and Gladstone 1984, Tsai et al 2006). This difference in the skull shape significantly affects the angular corners of Asian eyelids, as explains the more rounded outer corners in Caucasians and African Americans.
Secondly, the fibrous strip of tissue that defines the upper and lower lid margins, called the tarsus, is significantly narrower in the Asian patient (6-8mm) compared to Caucasians and African Americans (10-12mm). The upper edge of tarsus is where fine filamentous attachments link the eyelid skin to the eyelid, and corresponds to the height of the lid crease. It is these attachments that can be weak in Asians who do not have a visible lid crease, often called a “single eyelid” configuration.
Another difference is the additional layer of fatty tissue in the Asian eyelid that is not found in either Caucasians or African Americans. This extra layer of fat helps to separate the eyelid skin from the muscle and tarsus, which is typically firmly attached in Non-Asians. By increasing the thickness of Asian eyelids, this layer may also prevent a lid crease from forming at the upper border of tarsus.
June 13, 2008 at 11:19 pm |
WHY DID THEY EVOLVE THIS WAY?????
August 23, 2008 at 8:59 am |
[...] Os seres humanos não são geneticamente distintos entre si (no sentido de eu ter algo que o outro não tem). Isto aplica-se a todas as características físicas e não apenas à côr da pele. Os olhos dos asiáticos são diferentes dos olhos dos europeus não por terem informação genética diferente mas sim por produzirem mais gordura. [...]
February 22, 2009 at 6:31 am |
Hi,
It’s a matter of alignment check:
http://www.sharp-sighted.org/index.php?option=com_content&task=view&id=85&Itemid=153
best,
m.
March 9, 2009 at 9:49 am |
But why did this happen, or why did others not do this. WHY
April 3, 2009 at 8:56 am |
Hi Taw,
One theory could be that asians originally come from regions or time where/when there was a lot of ice and narrow eyes reduce the effects of the reflection of light on ice. When you look at Eskimo’s they have very narrow eyes.
An other theory could be that fishers who live on the water also had an advance from more narrow eyes, for the same reason reducing the effects of light-reflections on the water.
best,
m.
May 12, 2009 at 7:24 am |
Some Asians have partial eyelid separation and some have full separation. Mine are parted except right near the tear duct. I’ve not had my eyes surgically corrected. I’ve read some where that double lids as they’re also known are found in 75-80% of SE Asians and in 25-30% of NE Asians. I don’t know if it’s true, I’m adopted and most of the other Asian adoptees I see are of Korean descent and they’re not bothered with eye surgery so they keep the monolid look which I actually find very attractive with their eye shape.
January 1, 2010 at 3:59 pm |
they evolved this way because the people who migrated to asia right after the ice age had to deal with the brightness of the snow from the sun. for example when u look at the sun u squint your eyes. this is how they evolved.