What Is Astigmatism and Why Does it Make Your Vision Blurry?
This common vision problem can also cause an eye-strain headache—and typically is easily correctable.
Astigmatism, for a relatively common eye condition, is not an especially well-understood term. Simply put, it’s a condition that results when your cornea is irregularly shaped.
Because of this condition, light can’t focus on the retina in the back of the eye, making it harder for you to focus on what’s in front of you. In addition to blurry vision, astigmatism can also cause an eye-strain headache as you squint and try to overcome the blurriness on your own.
Fortunately, astigmatism—as diagnosed via an eye test—can usually be treated with the right pair of glasses.
Anatomy of the Eye
Astigmatism can be mild or severe, depending how much the cornea is misshapen. The cornea is the rounded, outermost layer of the eye. Within this thin, clear, outer layer are five thinner layers of tissue or membranes, each with its own function. Their jobs include protecting the eye from foreign objects and infection, as well as keeping the cornea flexible and able to allow light to pass through to the back of the eye.
The retina is the all-important feature in the back of the eye that converts the images you see into electronic signals that travel to the brain. The retina is also very light-sensitive, so if anything interferes with the light reaching it, the retina can’t focus clearly.
Astigmatism means your cornea isn’t smooth and even across its entire surface. One part may bend outward a little too much, or be flatter than another part. Even the slightest variations can affect the light reaching the retina. The majority of people have some form of astigmatism, but if it’s very mild, there won’t be a noticeable impact on vision.
Effects of Astigmatism
When you’ve struggled to see something close up, far away, or somewhere in between, you’ve probably squinted or leaned forward or leaned back. You’ve given your eyes a workout. These gyrations can cause an eye-strain headache while doing little to clear up your blurred vision. (See also our post “Glaucoma: Symptoms, Treatment, and Prevention of a Serious Eye Disease.”)
Adults who struggle with eye-strain headaches may seek out an ophthalmologist to find out what’s wrong. But children aren’t always so quick to complain or ask for help. And since astigmatism is something you’re usually born with, a child with vision problems and who gets the occasional eye-strain headache may not know any different. He or she may not realize that there’s a solution.
“Especially for school-age children, they won’t know that they have astigmatism, even if it requires correction,” says J. Daniel Twelker, OD, as associate professor in the Department of Ophthalmology and Vision Science at the University of Arizona. “They’re not going to generally come to a parent or a teacher and say they can’t see, draw or read at a grade-appropriate level.”
Dr. Twelker adds that correcting astigmatism can greatly improve a child’s ability to read and learn.
If an ophthalmologist has diagnosed astigmatism, you may be able to overcome your corneal imperfections with eye glasses or contact lenses. Glasses can be made with a special cylindrical lens that can correct for astigmatism. Standard soft-lens contact lenses may not be able to compensate for all types of astigmatism. A type of contact lens known as a toric lens, however, can usually do the job.
Your eye doctor may also recommend a therapy called orthokeratology. In the same way that wearing a retainer on your teeth at night can help realign your bite, rigid contact lenses worn at night can sometimes reshape the cornea. You may not need lenses during the day. Not everyone with astigmatism is a good candidate for orthokeratology. Ask your doctor whether this might be an option for you.
Certain types of LASIK or refractive surgery procedures may also help reshape the cornea and eliminate your astigmatism. These interventions focus on removing or treating the layer of the cornea causing the vision problem.
You have options when it comes to treating astigmatism. Don’t live with blurry vision and the occasional eye-strain headache. See an ophthalmologist soon and start your path toward clearer eyesight.
For further reading on related topics, refer to these University Health News posts:
Astigmatism can cause blurred vision and eye-strain headaches.
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