I assume you are referring to what some patients call their "triple eyelid", which can be present in one or both eyes.
For the majority of them, this skin fold is a result of hollowing or sunken upper eyelids that they were either born with or became prominent as part of the facial aging process. The multiply folded or sunken upper lid tends to make the eye(s) look "tired".
Treatment for sunken upper eyelids is challenging, even for an experienced doctor. Correction usually requires filling the sunken upper eyelid to lift the excess fold, either with natural hyaluronic acid fillers injection or surgically with autologous fat transfer (obtaining your own fat cells through gentle liposuction for injection and grafting into the area to be treated).
In individuals with aging eyes, non-invasive eyelid tightening treatments (such as radiofrequency skin tightening or NeoGen Plasma skin regeneration) to rejuvenate the loose, thin eyelid skin and saggy brows may be beneficial to freshen up the eyes and face as well.
In rare cases, the sunken upper eyelids can occur after previous eyelid surgery. These cases are best treated by their plastic surgeons, as surgery may be required to re-volumize and release any adhesions that may be present for better results.
