The first day or two after the surgery, the pupils will be unequal. Since the surgery is done behind the iris, the pupil has to be very large to do the surgery. After the surgery, drops are given to make it smaller again. Sometimes, they don't work well enough and the pupil is larger, sometimes they work too well and it is smaller. Within a few weeks, they should be the same size. It is possible to damage the iris in surgery. This can cause a change in pupil size or shape.