The success rate of any ptosis surgery is no better than about 80%
This means that 2 to 3 in 10 individuals under going ptosis surgery can have a result that may benefit from revisional surgery. You did not tell us when surgery was performed. If you just recently had ptosis surgery, be patient. Swelling from the surgery can weigh the eyelid down and this can take many weeks to slowly resolve. As it does, the eyelid will begin to open up. Honestly, I am very concerned if an eyelid is at the desired level right after ptosis surgery because this is generally an indication of an overcorrection. Of the two circumstances, I would rather deal with an under correction.