Well, first, you should know that it can be normal to have flashing lights after you have taken the surgery. At this situation, we can say that your eyes are likely to be infected, in some degree. Generally speaking, there are many reasons which can lead to this symptom. For example, it can be because of different diseases, disorders. But on the other hand, an infection or inflammation that irritates the eyes can also be the cause, when you have a surgery. As we know that after the surgery, your eyes are very sensitive and fragile, and it is easy for your eyes to be infected. When you have not taken care of your eyes, and let them infected, it can lead to flashing eyes. Anyway, just be careful about your eyes. You should not use your hands to touch your eyes frequently. Also, when having a shower, do not let the water get into your eyes, or it can carry some bacteria.
Well, so sorry to know that you have got cataract surgery. I think it is quite necessary since you want to stay healthy and do not want to be blind. As far as I know, it is quite normal to see flashing lights or eye floaters after the surgery because there must be some lasting impacts. However, you should not wait and do nothing, your immediate priority is to re-check your eyes and get some medical care.
After the cataract surgery, you'd better have a good rest for the eyes. You should not let the eyes see the strong lights. You'd better stay at home and close your eyes. However, your problem may be caused by not well protection for the eyes after the cataract surgery. It is not normal. You'd better go to see the doctor and have a full check on the eyes.