Very few people have perfect vision. Even if you’re born with perfect eyesight, most eyes eventually develop some sort of flaw that necessitates vision correction. Astigmatism is one of the most common types of refractive errors in which the cornea—the clear front part of the eye through which light is focused—is not perfectly round. It’s like trying to see clearly through a distorted windowpane, and blurry vision is the result.
“I think people have a better understanding of nearsightedness and farsightedness,” says Dr. Jay Pepose, founder and medical director of the Pepose Vision Institute and a professor of clinical ophthalmology at Washington University School of Medicine. “Astigmatism is still a mystery to many.” A cornea with astigmatism is similar to the shape of a football. Consequently, vision is blurred everywhere, whether an object is viewed from near or far.
“It causes light to not be focused at a single point,” Pepose explains. “And astigmatism is very, very prevalent.” Often, astigmatism is present from birth, although in some cases the distortion is minor. Others develop astigmatism with age.
For those who do need some sort of vision correction, glasses or contact lenses are often the chosen solution. “We consider not only the degree of vision correction needed but also the individual’s visual needs. Is that person spending a lot of time looking at a computer screen or reading, in which case correction is very important,” says Dr. Richard Levy, an optometrist with Erker’s Fine Eyewear.
While glasses are acceptable to many people, contact lenses also correct astigmatism. A special type of lens, known as a toric lens, corrects nearsightedness or farsightedness while including an extra correction on the vertical or horizontal axis to address astigmatism. The toric lens is weighted so that it stays in the proper position on the eye, keeping the correction stable.
“Toric lenses are just as comfortable as other soft contact lenses, and they’re disposable like other soft lenses,” Levy says. “Almost everyone with astigmatism can get a nice correction with glasses or toric lenses.”
However, some people benefit from a surgical solution. “Since more than 50 percent of people have astigmatism at the time of cataract surgery, the cataract surgeon is also interested in reducing pre-existing astigmatism,” says Dr. Sidney Hanish, owner of Hanish Eye Institute.
One surgical method for cataract correction that also lessens astigmatism involves the “design and position on the eye of the small incision we make to remove the cataract,” Hanish says. A second method is called astigmatic keratotomy (AK), in which incisions are made at the edge of the cornea in the direction and position needed to relax the curved cornea, and allow for a more spherical shape.
These approaches correct mild astigmatism, but cataract patients who have a more significant degree of astigmatism may be candidates for toric lens implant that lessens the problem and could allow the post-surgical patient to see without glasses.
Patients who do not have cataracts but seek surgical vision correction with the LASIK procedure also can have their astigmatism treated during surgery. This approach “may be more accurate in some patients than contact lenses,” Pepose says. “We have very accurate laser treatments now because when we sit down at the machine to take measurements, we encrypt the patient’s iris. The machine looks at details in the iris and comes out with a pattern, almost like a bar code. Then, when the patient lays down under the laser, if the eye rotates, the machine knows how to line up the treatment so it’s exactly on the axis of the astigmatism.”
Astigmatism is a common condition that need not cause long-term vision problems. Seeing your eye doctor for regular check-ups is a good first step. LN