Elevated blood pressure is almost never a reason to delay or cancel surgery. In some cases of secondary hypertension, very high blood pressure before surgery cannot be avoided, and the surgery itself is meant to correct the cause of the high blood pressure.
During surgery, a type of doctor called an anesthesiologist is responsible for monitoring your vital signs. In addition to putting you to sleep for the surgery, he also carefully watches your heart rate, breathing pattern and blood pressure. By studying your medical history and understanding the type of surgery being performed, the anesthesiologist knows what values each vital sign should have. During the surgery he will not only monitor these values, but will use intravenous drugs to correct them if they start to deviate from accepted values.
The drugs used to control heart rate and blood pressure during surgery are all given through an IV tube, are very fast acting, and extremely effective. Throughout the surgical procedure, all of your vital signs will be maintained at very close to their ideal levels.
For elective surgical procedures like cosmetic surgery or vision correction surgery, the surgeon may want to try and get your blood pressure as close to normal as possible before proceeding with the surgery. While this is not strictly necessary, it does reduce the risk of certain surgical complications. Since the surgery can safely be delayed as long as necessary, this approach is medically appropriate in these circumstances.
If you have any questions about how your blood pressure might affect your surgery, ask your anesthesiologist or surgeon. They will be able to discuss your specific case in detail and offer suggestions on how to proceed.