The incision that is required for IOL implantation during cataract surgery induces astigmatism —this is referred to as surgically induced astigmatism (SIA)— so the total amount of astigmatism to be corrected with the toric IOL must consider the flattening (FE) or steepening (SE) effect on the meridian of the preoperative corneal astigmatism on which the IOL is going to be aligned. The SIA will depend on several factors, including incision type, location and size, and its design or architecture.