Why do Asians have more eyelid ptosis than other ethnicities?

One feature that is unique among Asians is that many do not have double eyelid folds, or if they do, it is a small infold.  Of course there are some Asians, especially Southeast Asians that have larger double eyelid folds than Northeast Asians.  However, even the double eyelid folds in Southeast are lower in height, compared to the folds Caucasians.

It has been my clinical observation that Asians with no double eyelid fold or very small double eyelid folds have increased incidence of eyelid ptosis compared to those with inborn larger double eyelid folds.  Then the question is why?  As mentioned in the prior blogs, all muscle function increases with use, and muscles weaken with disuse.  Asians without double eyelid folds do not have a connection between the skin and the eye- elevating muscle.  Therefore, the eye-elevating muscle does not have the extra weight that is burdened.  Therefore, less effort is needed to lift the eye and thus the muscle does not increase in strength.  Think of a person who does not do weight training.  The muscle will stay thin and its power will be less than that of a person who has trained their muscles with weights.  How about a person with very small double eyelid infolds?  The connection between the skin and the eye-elevating muscle (levator aponeurosis) is low, so the volumetric amount is significantly less that in a person with a higher double eyelid folds (volumetric difference is cubed – 3x).  Hence, this person has less weight bearing on the eyelid-elevating muscle and thus is not subjected to appropriate “weight training.”  This effect of weight training needs to be done throughout development as the eyes and the rest of the body grows.  However, these eye muscles develop without any resistance or load bearing.  Thus, the muscle remains weak.

In addition, since Asians without double eyelid folds or very small double eyelid folds have skin that hoods over, forehead muscles are activated to lift the eye.  Because the forehead aids in eye opening, the eyelid-elevating muscle (levator muscle) does not contract and work fully (limited excursion).  Therefore, the eyelid muscle is not optimally exercising and developing into a healthy muscle.  And as mentioned in the prior blog, limited full range of eye muscle movement causes stiffening around the muscle (fibrosis) and further limits its optimal function.

Now, with this diminished eye elevating function, the person who wishes to have double eyelid surgery may believe that having a double eyelid fold will make their eyes bigger and open better, because they see others with congenital double eyelid folds (Asians or Caucasians) or people who had surgically created double eyelid folds open their eyes widely.  Yet, what they failed to see is that people who were born with double eyelid folds had “weight training” since birth and people who had double eyelid surgery often had surgery early such as in their teenage years (13-18 yrs of age) when the eyes muscles were still developing.

As you can realize, double eyelid fold and eyelid ptosis is intimately related.  The plastic surgeon must be cognizant of the developmental, functional, and aesthetic aspects of the person and choose the ideal surgery for the individual.