What is Astigmatism?

The majority of the focal power of the eye is determined by the shape of the cornea, which is the clear front surface of the eye. In some eyes, the cornea is spherical, or shaped like a baseball, with the same curve in every direction. This type of eye does not have astigmatism. Most eyes, however, have a flatter curve in one direction and a steeper curve in the other, like an egg or a football. This type of eye has two different focal powers, which results in a slight ghosting or doubling of the vision. This is call astigmatism.

How is Astigmatism corrected?

People with astigmatism have many options for vision correction. Astigmatism can be corrected with: 1) glasses or contact lenses, 2) LRI [limbal relaxing incisions] 3) laser refractive surgery, either LASIK or PRK or 4) toric intraocular lens, used after cataract removal.

I am having cataract surgery. Do I need to worry about my Astigmatism?

It is important to remember that most people have astigmatism, and that at low levels, uncorrected astigmatism does not pose a significant vision problem. However, at moderate to higher levels some form of correction is necessary for clear, sharp vision. This may mean wearing glasses after surgery. For those who want to reduce the need for glasses after cataract surgery, LRI (limbal relaxing incisions) or the use of a toric intraocular lens are possible options.

What is a toric intraocular lens and how does it work?

For moderate to high levels of astigmatism, your surgeon may prefer to use an intraocular lens to correct the astigmatism. Every eye undergoing cataract surgery receives an intraocular lens (IOL or “implant lens”) when the cataract is removed. The natural lens of the eye (which becomes the cataract) gives the eye about 25% of its focal power, so must be replaced in order to see well after its removal. Regular (also called “standard”) IOLs only correct near-sightedness (myopia) or far-sightedness (hyperopia), because they contain only one correction of power. Toric intraocular lenses correct astigmatism as well as myopia or hyperopia due to the fact that they contain more than one correction of power.

What exactly is the LRI and how does it work?

For low to moderate levels of astigmatism, limbal relaxing incisions, or LRI, can be performed. Limbal relaxing incisions are small incisions made in the outermost area of the cornea near where the cornea (clear part overlying the iris and pupil) and the sclera (white part of the eye) meet. The incisions allow the steeper corneal curve to relax, causing the cornea to take on a more spherical shape.

Which of these options is best for me?

Your surgeon will discuss these options with you and make a recommendation based on the level of astigmatism you have and the anatomy of your eye. Please ask questions to ensure that you fully understand your options. Remember, not all people need or want surgical correction of their astigmatism. Also, be aware that surgical correction of astigmatism will not eliminate the need for reading glasses after cataract surgery.

Where Can I Get More Information?

To schedule an appointment call 414-271-2020.