The most common cause of sunken upper eyelids (or upper eyelid hollowness) is due to Aging-related soft tissue and bone loss.
The other causes of sunken upper eyelids are due to genetics and post eyelid surgery volume loss.
Treatment options will depend on the exact causes/s of your sunken upper eyelids. It is best to be assessed in person by an experienced aesthetic doctor.
Hollowness (aka Volume Loss) will require Filler injections to correct the hollowness/volume deficit. This is a challenging region of the face so please look for an experienced Filler injector for best results and to minimise complications.
Depending on which filler is being used, results can last from 9 to 18 months.
The choice of fillers is also dependent on the severity of your volume loss.
Alternatively, Fat grafting of upper eyelid fat pads by a plastic surgeon can also be performed.
Hope that this helps!
Warmest regards,
Dr Justin Boey