Your correction or prescription is the actual lens power within your glasses or contact lenses. It is the slip of paper that your eye doctor gives to you for your glasses to be made. Every prescription is different and unique for each person’s eyes. That is why each surgery has to be tailor-made to each specific patient.
For example: (-4.00 +2.00 x 180). The first number, -4.00, indicates four diopters of nearsightedness. The second number, +2.00, indicates two diopters of astigmatism oriented at 180 degrees. Astigmatism means that your eyeball is shaped more like an oval than a round circle, and therefore, the oval is pointing at the 180 axis. Your correction/prescription is the most important number for the surgeon. These are the numbers used to decide what type of surgery is best for you and the actual numbers needed to program into the laser.