Surgical Astigmatism Correction
Astigmatism is likely the most misunderstood vision problem. In an eye with astigmatism, light fails to come to a single focus on the retina to produce clear vision. Instead, multiple focus points occur, either in front of the retina or behind it (or both).
Astigmatism usually causes vision to be blurred or distorted to some degree at all distances. Symptoms of uncorrected astigmatism are eye strain and headaches, especially after reading or other prolonged visual tasks.
There are several ways modern cataract surgery can correct astigmatism. One option is to replace the eye’s cloudy natural lens with a special type of premium intraocular lens (IOL) called a toric IOL. A toric IOL works much like toric contact lenses for astigmatism. That is, it has different powers in different meridians of the lens to correct the unequal amount of nearsightedness or farsightedness in different parts of the eye that is characteristic of astigmatism.
If you have astigmatism, a toric IOL may reduce your need for eyeglasses after cataract surgery. There is an advantage of using a toric IOL to correct astigmatism when a cataract is removed: Because the IOL is positioned securely inside the eye, it can provide a more stable correction of astigmatism than a toric contact lens, which moves on the surface of the eye with each blink. Due to the higher cost of a toric IOL and additional required testing, the cost of cataract surgery that includes astigmatism correction generally will be higher than that of a standard cataract surgery.
Another way to correct astigmatism during cataract surgery is called limbal relaxing incisions (LRI). In this procedure, one or more arc-shaped incisions are made near the periphery of the cornea. This gently reshapes the cornea into a more spherical shape, eliminating astigmatism.