Astigmatism is caused by the cornea being more curved in one direction than the other, like a football. Usually, the cornea is more rounded, like a basketball. Astigmatism can cause an image to be out of focus even after cataract surgery. Cataract surgery provides an opportunity to also “correct” the astigmatism at the same time. There are 3 possible options when dealing with both cataracts and astigmatism:
The first option is to not attempt to “correct” the astigmatism while performing the cataract surgery. The astigmatism can be dealt with by prescribing a new pair of glasses after the eye heals from cataract surgery completed with a standard IOL.
Limbal Relaxing Incisions
The second option is to perform limbal relaxing incisions (LRIs) at the time of cataract surgery. LRIs can be used to treat low to moderate levels of astigmatism. In this case, a standard IOL is inserted after cataract extraction. LRIs are incisions placed in the cornea along the steep axis of curvature. They basically “relax” the steep part of the cornea, and allow it to take a more regular round shape. Generally, LRIs take less than one minute, and are easily combined with cataract surgery.
The third option is to insert a toric IOL instead of a standard IOL during the cataract surgery. Toric IOLs are specially shaped IOLs designed to offset the imbalance created by the irregular shape of the cornea. Once implanted during surgery, they stay fixed in place thereby eliminating pre-existing astigmatism. This can be used to treat low, moderate, and high levels of astigmatism.
Dr. Rhodes will discuss with you which options would most likely work for your eyes prior to cataract surgery.