Dr. Lee Jung Min from Wonjin hospital 

Protruding and uneven under eyes can give you a dark and tired impression due to ptosis, on the other hand, sunken under eyes or dark circles could be caused by under eye fat.

Under eye correction requires no skin incision. The excessive fat is transferred to areas that lack fat to make the under eye flat, and if sunken under eyes are severe, under eye correction with fat grafting can improve fine wrinkles and dark circles

In the past, under eye correction was known as a surgery that was only performed due to aging. Recently however, this surgery method is being decided upon according to the amount of under eye fat, degree of fat dispersion, and wrinkles, without considering age. Because the surgery is done through the inner conjunctiva, there is no skin incision and no visible scar. The operation time is also relatively short as there is no swelling or bleeding because there is no excessive peeling and fat is injected into the required area so that blood does not accumulate.

Lower blepharoplasty can help middle aged people who have severe sagging skin and excessive fat because it removes excess skin and corrects the saggy fat and tissue.

Accordingly, Dr. Lee Jung Min said, "Under eye bag correction requires delicate surgery since the skin in that area is very weak and thin. As such, it is advised to create a plan through proper consultation with a skillful surgeon who has extensive medical experience."

Source - http://www.stardailynews.co.kr/news/articleView.html?idxno=266248