Sometimes You See Them Sometimes You Don't aka The Elusive Double Eyelids in East Asians

Double eyelids are seen in 50% of Chinese, however, not all of these double eyelids are stable. It is not uncommon to see patients in clinic who complain that their double eyelids sometimes disappear at the end of the day and reappear when they wake up or vice versa. The reason for these unstable double eyelids is the result of weak insertion of the levator muscle (the muscles that open the eyes) into the skin. This weak insertion is thought to be caused by the forward protrusion of the fat pad in Chinese which interferes with the muscle insertion.  In some patients, the double eyelids become more apparent with age as a result of fat shrinkage (fat atrophy) making the insertion more stable.

The pictures show a cute baby with single eyelid who occasionally develops double eyelids on waking up.

Normal eyelid appearance.

Double eyelids on waking up.