Well, yes, it is possible to have eyelid ptosis because of blepharoplasty.and generally speaking, after the surgery your eyes can be sensitive and weaker. So if you overuse your eyes, it will lead to high eye pressure. And in that way, it will cause ptosis, for ptosis is usually caused by high eye pressure. For example, if you watch too much tv after the surgery, it will make you have high eye pressure, and this can be a factor which can lead to eyelid ptosis. Also, you should know that eyelid ptosis is often caused by depression. So just avoid overusing your eyes after the surgery. Also, try to have a good rest.