What is considered mild astigmatism?

Contents

When Astigmatism Throws Vision Out of Focus

Even if you can see perfectly well without glasses or contact lenses, there’s a decent chance that you could still face a common eye condition known as astigmatism. Astigmatism affects the cornea, which is the clear window of tissue on the front of your eye that sits over the pupil (the black dot you see in the center of your eye). As light enters your eye, the cornea helps to properly focus it onto the retina, the light-sensitive tissue at the back of your eye.

In someone with no astigmatism, the cornea is shaped “exactly like half a basketball in front of the pupil,” says Majid Moshirfar, MD, director of refractive surgery services at the Moran Eye Center at the University of Utah. For most of us, though, the cornea is formed more like half an egg, and the curvature is slightly different in each direction. When astigmatism grows severe enough, light cannot focus as well on your retina, and your vision may become blurry.

Generally, people have astigmatism from birth, and the condition may be inherited from your parents. Researchers are currently trying to figure out the exact role that genes play in the development of astigmatism by studying its connection in twins.

Diagnosing Astigmatism

Doctors measure the severity of astigmatism in units called diopters, Dr. Moshirfar says. If you have less than 0.6 diopters of astigmatism, your eyes are considered normal. Between this level and 2 diopters, you have a small degree of astigmatism. Between 2 and 4 is moderate astigmatism, and above 4 is considered significant astigmatism.

Eye Care Options for Astigmatism

Luckily, your eye doctor can offer several types of treatment for astigmatism, depending on its severity.

If you have up to a moderate level of astigmatism, your eye doctor may be able to treat the problem with contact lenses, Moshirfar says. A special kind of soft lens can be used for astigmatism. A hybrid contact lens that is hard in the middle and soft around the edges is also sometimes prescribed to people with astigmatism, he says. Or, you may be able to use a rigid, gas-permeable lens.

If your astigmatism is up to 5 or possibly 6 diopters, your doctor may be able to treat the problem with a laser. In LASIK surgery, the doctor uses a laser to change the shape of your cornea and fix the astigmatism. It’s important to know, however, that when you have higher degrees of astigmatism, surgery is unlikely to completely get rid of the distortion is causes, Moshirfar cautions.

Treating More Serious Cases of Astigmatism

If you have very severe astigmatism, Moshirfar urges that you ask your doctor to test you for a disorder called keratoconus,. In this condition, the cornea becomes thin and cone-like in shape. Although rigid contact lenses may help correct your vision in earlier stages of keratoconus, some people with keratoconus will end up needing a corneal transplant.

If you have both astigmatism and cataracts, the two problems can actually be treated by the same procedure, Moshirfar says. Cataracts occur when the lens — the tissue that lies beneath the cornea — becomes cloudy. Doctors can replace the damaged lens with an artificial one. This same new lens can also be used to correct your astigmatism. And, most importantly, it can keep you seeing clearly for years to come.

What is astigmatism?

Conditions

By Gary Heiting, OD

Astigmatism is a type of refractive error caused by the irregularities in the shape of a person’s cornea. In this condition, the eye fails to focus the light equally on the retina leading to blurred or distorted vision. It can be present at the time of birth, or can develop gradually in life.

Astigmatism is a common eye condition which usually occurs with myopia (nearsightedness) or hyperopia (farsightedness) and can be easily diagnosed with a simple eye exam.

Astigmatism is a refractive error and is not an eye disease or eye health issue.

Astigmatism is simply a problem with how the eye focuses light.

Astigmatism usually causes vision to be blurred or distorted to some degree at all distances. Some of its symptoms are eye strain, headaches, squinting and eye irritation.

What causes astigmatism?

Astigmatism is usually caused by an irregularly shaped cornea. Instead of the cornea having a symmetrically round shape (like a ball), it is shaped more like an egg, with one meridian being significantly more curved than the meridian perpendicular to it.

(To understand what meridians are, think of the front of the eye like the face of a clock. A line connecting the 12 and 6 is one meridian; a line connecting the 3 and 9 is another.)

The steepest and flattest meridians of an eye with astigmatism are called the principal meridians.

In some cases, astigmatism is caused by the distortion of shape of the lens

inside the eye. This is called lenticular astigmatism, to differentiate it from the more common corneal astigmatism.

It’s important to schedule an eye exam for your child to avoid vision problems in school from uncorrected astigmatism.

Worried about astigmatism? Find an eye doctor near you and schedule an appointment.

3 types of astigmatism

There are three primary types of astigmatism:

  • Myopic astigmatism. One or both principal meridians of the eye are nearsighted. (If both meridians are nearsighted, they are myopic in differing degree.)
  • Hyperopic astigmatism. One or both principal meridians are farsighted. (If both are farsighted, they are hyperopic in differing degree.)
  • Mixed astigmatism. One prinicipal meridian is nearsighted, and the other is farsighted.

Astigmatism is also classified as regular or irregular. In regular astigmatism, the principal meridians are 90 degrees apart (perpendicular to each other). In irregular astigmatism, the principal meridians are not perpendicular.

Most astigmatism is regular corneal astigmatism, which gives the front surface of the eye an oval shape.

Irregular astigmatism can result from an eye injury that has caused scarring on the cornea, from certain types of eye surgery or from keratoconus, a disease that causes a gradual thinning of the cornea.

Astigmatism tests

Astigmatism is detected during a routine eye exam with the same instruments and techniques used for the detection of nearsightedness and farsightedness.

Your eye doctor can estimate the amount of astigmatism you have by shining a light into your eye while manually introducing a series of lenses between the light and your eye. This test is called retinoscopy.

Astigmatism correction options

Astigmatism can usually be corrected with eyeglasses, contact lenses or refractive surgery.

Refractive surgery is one of the less common astigmatism correction options, however, since it is a laser procedure that changes the shape of your eyes, it comes with risks associated with most surgeries.

Astigmatism should be treated as soon as possible. Once diagnosed, regular visits to an eye doctor are required as astigmatism can fluctuate over time, making it necessary for prescriptions to be modified.

Page updated August 20, 2018

Schedule an exam.

Find an eye doctor near you.

A guide to astigmatism

There’s often a lot of confusion about what it is, including its effects and treatments. So, to clear things up, this guide will help to demystify the condition and provide practical tips to correct it.

Let’s define astigmatism.

Astigmatism is a common eye condition caused by a refractive error in the eye’s lens, which can result in blurred vision. This error happens when the eye’s cornea or lens is irregularly shaped. The condition is easily corrected with contact lenses or glasses.

There are two categories of astigmatism. Corneal astigmatism (also known as regular) which is caused by a distorted cornea and lenticular astigmatism (also known as irregular) which is caused by a distorted lens.

Corneal is the most common form, this occurs when the cornea is irregularly curved in one direction more than the other. The shape of the eye in this case is commonly said to look more like a rugby ball than a football. Lenticular astigmatism can be recognised by an optician from the irregular curvature of the eye’s lens, often in multiple different directions.

Although there are two main reasons or categories for astigmatism there are actually three ways your vision can be affected, they are classified as: myopic (nearsightedness), hyperopic (farsightedness) and mixed (a combination of near and farsightedness).

Astigmatism symptoms

  • Blurred vision, short and long
  • Eye strain
  • Headache
  • Squinting
  • Difficulty seeing at night, which can affect driving

Astigmatism is usually found alongside other eye conditions notably short-sightedness and long-sightedness.

How to test for astigmatism

If you are experiencing any of these common symptoms or a combination and think you might have astigmatism, simply book an eye test with your optician. You don’t need special equipment or to visit the doctors.

If you’re uncertain and don’t have time for a trip to the optician, you can always do a preliminary test at home. There are two simple tests you can do to determine the level of astigmatism in your eyes, the dial test and the line test, visit vision and eye health to find out for yourself.

Common myths of astigmatism

1. Astigmatism can cause blindness

Astigmatism is not so serious that it causes blindness. However, it can make life harder, as vision can become blurred.

2. Astigmatism is only inherited at birth

While astigmatism can be present at birth, it can also develop at any stage of life. Although optometrists don’t unanimously agree why astigmatism develops, they do agree it’s likely to be passed through family genes. It can also follow an injury, eye surgery or eye disease. Because it can be hereditary, it’s a good idea to test for astigmatism in children at a young age.

3. Reading in the dark or sitting too close to the TV can cause astigmatism

No, it’s a myth. Sitting too close to the TV or reading in the dark will not cause astigmatism, but it can weaken the eyes leading to eyestrain, tiredness and headaches. Read more at essilor.com.

People sometimes ask, ‘can too much screen time damage my eyes?’, sorry the answer is yes. Too much screen time, whether you’re overexposed to white light at work or browsing your mobile at the weekend can lead to digital eye strain. Sadly, it affects children too, especially if they are glued to their tablets for many hours at a time.

4. Astigmatism can correct itself

Despite some online articles claiming otherwise, astigmatism won’t get better over time. Astigmatism, as with any eye condition can worsen with age. Don’t worry there are options to alleviate the condition.

Can astigmatism be corrected with contact lenses?

If you’re here, you’ll be wondering to yourself: ‘can astigmatism be corrected with contact lenses?’. Luckily, the short answer is yes. Specifically, with toric lenses.

Toric lenses are shaped to fit an eye with astigmatism, if you have astigmatism, you might find that normal lenses won’t do the trick and move around a bit while you wear them. Toric lenses solve this problem, staying firmly in place – some are even more heavily weighted at the bottom to ensure they don’t move – allowing you undisturbed clear and comfortable vision.

One of our top selling toric lenses is 1 Day Acuvue Moist for Astigmatism. If you find your current astigmatism lenses aren’t comfortable, try them today.

Related links

  • Check out our full range of Toric Contact Lenses and find the best solution for you.
  • Find out more about common vision problems and much more by visiting our Eye care centre.

9 Facts You Didn’t Know About Astigmatism

If you’re a glasses or contact lens wearer, this question might have come up before: “Do you have astigmatism?” If you’re not quite sure how you should answer, then this blog post is for you. We’re going to share some of the more common facts about astigmatism, as well as tell you what symptoms you can and should look out for, and the steps you can take to treat them.

1. Astigmatism is caused by an irregularly-shaped cornea

If you have astigmatism, then you’ve surely experienced out-of-focus eyesight from any distance. This is due to the fact that your cornea (the transparent surface of the eye) is football-shaped instead of the more normally-spherical structure of an emmetropic eye (when light rays that enter the eye come to perfect focus on the retina; this is ideal vision). With a rounder shape, the eye can properly control the amount of light that enters, making it easier to see clearly. An irregularly-shaped eye, however, means that the light that enters is unevenly distributed, thus resulting in blurred vision.

2. The cause of astigmatism is (somewhat) unclear…

While we know the answer as to why a person’s eyesight is blurry (an irregularly-shaped cornea) and what affect this can have on vision, many optometrists and researchers still aren’t sure as to how this happens in the first place. What we do know is people who have astigmatism are typically born with this this condition, meaning their eye resembles a football to begin with. Though much less likely, trauma or injury to the eye may force this shape to shift too. One way you can’t get astigmatism, though, is by sitting too close to the television. While this was once believed to be a sure-fire way to develop the condition, consider that myth debunked.

3. There seems to be a genetic component

You can thank your mom and dad for this one: as previously mentioned, an oddly-shaped cornea is a genetic trait, just like the colour of your eyes, which may have been passed down from one generation to the next. So the blurry vision you start to notice over time may very well be out of your control.

4. Astigmatism symptoms may be easy to miss

One of the most widely-reported symptoms of astigmatism—blurry vision—can be so mild in some people that it can hardly be detected. Other symptoms, like headaches or eye fatigue, are so commonplace that they can easily be overlooked or mistaken for another issue (too much time spent in front of a computer, for example). That’s why, like other aspects of your overall health, it’s important to stay vigilant with regards to your vision. Performing every day, routine tasks like using a computer, smartphone, tablet, or even just reading a book may all provoke blurry vision. The best way to know what’s happening with your eyesight is to get it checked regularly by an optometrist.

5. Catch symptoms early on to avoid complications

Astigmatism is important to catch early on, especially in children. If left unnoticed, it can lead to more serious and permanent eye conditions such as amblyopia (the scientific term for what’s commonly known as lazy eye). As mentioned above, regular eye exams should be considered essential: get your (and your children’s) eyes checked every year to avoid complications to your eyesight.

6. An optometrist can easily detect astigmatism

Though you might have a hard time identifying the exact cause of your blurred vision, an eye doctor should be able to clear things up for you. With a comprehensive eye exam, your doctor will measure your visual acuity (your eye’s ability to make out details and shapes), asking you to read out letters on an eye distance chart. A series of lenses will be placed over your eyes—these will test your eye’s ability to focus. Your eye doctor may even perform a corneal topography exam to measure other qualities that are unique to your eyes.

7. There’s more than one type of astigmatism

There are three types of astigmatism:

  • Myopic astigmatism: This form of astigmatism occurs when the light is focused before it ever reaches the eye, much like myopia itself.
  • Hyperopic astigmatism happens when one or both of the eye’s meridians (invisible lines that run from right to left and top to bottom) are farsighted (people who can see clearly from up close but have difficulties seeing far away). This occurs with hyperopia.
  • Mixed astigmatism is the result of one principal meridian being near-sighted, with the other being farsighted.

No matter what form of astigmatism you’re afflicted by, it can be corrected easily with refractive surgery (such as LASIK), glasses, or contact lenses.

8. Symptoms of astigmatism will grow worse over time

If you have astigmatism, and have not had it corrected it through surgical means, there’s a significant chance you’ll notice the quality of your vision declining over time. This deterioration can happen slowly…but eventually, it’ll become all too difficult to ignore. However, there is some good news: astigmatism isn’t an eye disease, this change in vision poses no real threat to your overall eye health—it may just make things look even blurrier than they did before.

9. Astigmatism can affect depth perception

Depth perception means the ability to observe the world in three dimensions. Some eye conditions, like astigmatism, make depth perception issues seem much more apparent—making it difficult to determine the proximity of certain objects or the distance between two objects.

A lack of depth perception is more likely to be a symptom when only one eye is afflicted by astigmatism, as it can create a profound feeling of imbalance. Astigmatism also blurs the edges and outlines of everything you see, so even if your depth perception is untouched, the overall quality of your vision may be poor regardless.

Here is one way you can correct astigmatism

If you find your blurry vision extremely bothersome, one of the easiest ways to simplify complications of astigmatism is with LASIK eye surgery. LASIK permanently reshapes the cornea, bringing it to a rounder shape to help you see clearly. Glasses and contact lenses may also be prescribed to you to correct astigmatism. In some cases, the astigmatism may be so slight that your doctor may not recommend wearing glasses at all.

If you’re tired of having eyesight that’s always out-of-focus, there is an easy solution: laser vision correction. Want to know if you’re a candidate for this procedure? We recommend booking a free consultation with our helpful clinical staff to see if a vision correction procedure can help you.

Refractive Errors and Vision Correction Surgery Dallas Fort Worth

Myopia

Myopia is the most common form of refractive error and affects nearly 30% of the U.S. population. If you are nearsighted, you can take off your glasses or contacts and see objects clearly when held at a close range, but objects in the distance will appear blurred.

Myopia is caused either by an eye that is too long, a cornea that is too steep, or a combination of these two causes. Most nearsighted people feel that they have “bad” eyes. This is not really true. A nearsighted eye is usually healthy. It just has an abnormal focal length. This abnormal focal length can be corrected with glasses or contact lenses, which change the focus or power of the eye thus correcting the vision.

Of all myopic people, about 90% have corrections less than -6.00 diopters. The categories below indicate the severity levels for myopia:

Almost everyone feels that his or her myopia is severe because of how dramatically dependent he or she is on glasses or contact lenses. However, only one in ten myopic people are actually in the high or extreme categories.

In order to surgically correct the myopic eye, the focusing power of the cornea must be reduced. This can be accomplished by flattening the central portion of the cornea with a refractive procedure such as PRK or LASIK.

Hyperopia

Hyperopia, or farsightedness, is the opposite of myopia. In this condition, the image of concern is focused behind the retina, creating blurry vision. The hyperopic person cannot see clearly up close or at distance.

Hyperopia occurs when the eye is too short or the cornea is too flat. Just as in myopia, hyperopia can be corrected with contact lenses or glasses. If hyperopia is to be corrected by a surgical procedure, the focusing power of the cornea must be increased. This is accomplished by steepening the cornea. As you can imagine, producing a steepening effect on the cornea with a laser is more difficult than flattening the cornea.

Astigmatism occurs when the cornea has an irregular shape. A normal cornea is shaped like the surface of a basketball, a round surface. A cornea in an eye with astigmatism is shaped like a football, or like the back surface of a spoon. This condition often occurs along with either myopia or hyperopia and causes light to focus in more than one point on the retina, producing blurry vision.

Astigmatism is also measured in diopters. Of all myopic people, 50% or more have astigmatism as well. Most of these people have corrections of less than 1 diopter. The table below shows the categories of severity for astigmatism:

  • Mild Astigmatism <1.00 diopters
  • Moderate Astigmatism 1.00 to 2.00 diopters
  • High Astigmatism 2.00 to 4.00 diopters
  • Extreme Astigmatism > 4.00 diopters

Presbyopia

Presbyopia, “aging vision,” is probably the most difficult refractive error to understand. Inside the eye, the lens changes shape in order to focus objects at various distances from the eye. If an object is far away, the lens becomes flat and skinny, producing less focusing power. If the object is close, the lens becomes round and fat, with more focusing power. Between the ages of 42 to 45, most people begin to lose the ability to focus up close, thus requiring reading glasses. This is presbyopia.

If you are nearsighted and become presbyopic, you can take off your glasses or contacts and still see up close. This issue becomes important if you are considering refractive surgery such as LASIK. In most cases, LASIK is performed to correct your vision for distance focusing. If you are 45 or older and undergo LASIK, you will need to plan on wearing reading glasses for close work. This is a complicated issue and you will have the opportunity to discuss this topic with your physician prior to your surgery. Recent advances in lens options for cataract surgery have enabled our surgeons to address presbyopia correction when performing cataract surgery.

Astigmatism: Q&A

Conditions

Questions answered by Burt Dubow, OD; Gary Heiting, OD; and Charles Slonim, MD

Q: Does

go away? — E., New York

A: Sorry, no. In fact, sometimes astigmatism gets worse with age…but slowly. It is probably partly hereditary and partly environmental. Most astigmatism can be easily corrected with eyeglasses, contact lenses and refractive surgery; but significant astigmatism won’t go away on its own. Fortunately, it is not a fatal condition! — Dr. Dubow

Q: Could you please explain what is meant by the term “mixed astigmatism,” and if this condition can be treated with LASIK? Thank you. — F.G., California

A: In mixed astigmatism, the unequal curvature of the cornea (and sometimes also the lens inside the eye) causes one meridian of the eye to be farsighted and a second meridian (perpendicular to the first) to be nearsighted.

Mixed astigmatism usually can be successfully treated with LASIK, but results might be less predictable than surgical correction of simple nearsighted astigmatism. Your eye doctor can discuss this with you in detail at your LASIK consultation. — Dr. Heiting

Q: I have astigmatism. Would you recommend wearing contact lenses or just glasses? — R.M., California

A: It’s your choice. Both contact lenses and eyeglasses can correct astigmatism. Refractive surgery, such as LASIK or PRK, also is an option. — Dr. Dubow

Q: My eye doctor told me in my eye exam that my astigmatism got worse. Is this normal? I heard that astigmatism’s not supposed to change. — T.J., Minnesota

A: When it comes to your eyes, it’s always best to trust your eye doctor rather than what you hear elsewhere — unless that “elsewhere” is another eye doctor at AllAboutVision.com!

Astigmatism is a very common vision problem. In fact, most people have some. When you have astigmatism, light does not focus to a single point in your eye. Instead, it causes blurred vision because the front of the eye is shaped more like an American football than a baseball.

Unfortunately, astigmatism can (and often does) change throughout your life, usually for the worse with age. But astigmatism is not a disease and can be compensated for with glasses, contact lenses or

— Dr. Dubow

Q: Our son is almost 10 years old, and he had his first eye exam recently because he failed a school vision screening. The eye doctor said he has a lot of astigmatism in one eye, and a lesser amount in the other, and that he needs to wear glasses all the time because he has “lazy eye” in the eye with more astigmatism.

The doctor went on to say that the lazy eye might be permanent because the astigmatism wasn’t detected sooner. Is this true? — S.W., Oregon

A: It’s true that uncorrected astigmatism can cause amblyopia (or “lazy eye”). In the past, it was believed that there is a “critical period” in childhood during which amblyopia treatment must begin or decreased vision will be permanent. Many people believed this critical period ended around age 8 or 9.

But recent studies of brain function and a phenomenon called neuroplasticity are dispelling the belief that amblyopia treatment is ineffective beyond a certain age in childhood.

Be sure your son wears his eyeglasses full-time and sees an eye doctor for routine exams to monitor his vision development. Initially, he should be seen more frequently than once a year.

You also might want to take him to an eye doctor who specializes in children’s vision and amblyopia treatment. A program of prescribed visual activities (called vision therapy), along with full-time wear of glasses, often is more effective at reducing or eliminating amblyopia than simply wearing prescription eyeglasses. — Dr. Heiting

Q: Will my astigmatism worsen if I don’t wear my glasses all the time? If I do wear my glasses all the time, will this somehow reduce my astigmatism, or will it make my astigmatism worse? Are there any medications that can reduce astigmatism? — R.C., California

A: Wearing or not wearing your eyeglasses will not make your astigmatism better or worse. If your astigmatism worsens, this will occur whether or not you wear your glasses. At present, there is no known medicine that can reduce astigmatism.

But I recommend that you do wear prescription glasses or contact lenses (or consider LASIK or other vision surgery to correct your astigmatism) if your vision is bothersome without corrective lenses. Also, even mild uncorrected astigmatism often causes headaches and eye strain.

And, depending on the severity of your astigmatism, it may be dangerous (and illegal) for you to drive without corrective lenses. — Dr. Heiting

Q: I’ve worn glasses before, but I was just prescribed glasses for astigmatism for the first time. My new glasses make me dizzy when I wear them. I’ve had them for three days. Will this feeling go away, or should I go back to my eye doctor? — Tom, Indiana

A: It’s true that sometimes it takes a period of adjustment to get used to glasses that correct astigmatism — especially if you have moderate or severe astigmatism or a significant change in your astigmatism prescription.

Since it’s been three days and you are still uncomfortable (I’m assuming you are wearing the glasses full-time), I recommend you return to your eye doctor to make sure your new eyeglasses prescription is correct and your lenses were made properly. — Dr. Heiting

Q: At what age can children have LASIK surgery to correct astigmatism? — B., California

A: You don’t want to proceed with LASIK surgery until you are reasonably certain your child’s eyes have stopped changing. Many kids who have astigmatism also have some nearsightedness, which often continues to worsen in the teen years. In most cases, the minimum age for LASIK is 18 years, and some people should wait longer.

— Dr. Heiting

Q: My eye doctor told me that I have astigmatism in one eye and said I could get glasses if I wanted to. He didn’t seem too worried about it. Should I get glasses? — J., New York

A: If you have only mild astigmatism in one eye, you see acceptably well without glasses (20/40 or better, which is the legal requirement for driving), and you are not bothered by eye strain or headaches as the day goes on, prescription eyeglasses certainly are optional. But if your vision bothers you or you experience headaches or eye strain, I recommend them.

If you are uncertain, you might want to go back to your eye doctor and have him or her show you again how much better you will see with prescription lenses. This can be demonstrated in the exam room without the need for you to purchase glasses first. — Dr. Heiting

Q: My eyeglasses prescription says the axis of my astigmatism is 140 degrees. But when I got my glasses checked, the optician said the axis is 160 degrees. Is it harmful to wear these glasses? Will it make my astigmatism worse? — S., India

A: It won’t harm your eyes or make your astigmatism worse, but wearing glasses with an incorrect astigmatism axis of this magnitude (depending on the amount of astigmatism you have) will usually cause blurred vision, eye strain and other discomfort. Return to your eye doctor at your earliest convenience to recheck your prescription and the eyeglasses. — Dr. Heiting

Q: I had cataract surgery in both eyes, and it feels like I see less well now than before the surgery. I was told I have irregular astigmatism. I did get glasses, which corrected it somewhat, but without them my vision is worse than it was before cataract surgery. Can anything be done? — J.P., Connecticut

A: You may have more than one type of astigmatism since your cataract surgery. Eyeglasses can correct regular astigmatism, but they usually cannot correct irregular astigmatism.

Sometimes, astigmatism (both regular and irregular astigmatism) is induced by cataract surgery. This is because an incision must be made in the front of the eye for the surgery, and as this wound heals it can change the curvature of the clear front surface of the eye (cornea). Also, sometimes astigmatism can be caused by the placement of the lens implant inside the eye or the implant itself.

If you are unhappy with your vision without corrective lenses after cataract surgery, often there are options to improve your eyesight with a follow-up refractive surgery procedure. If you’ve not yet discussed this possibility with your cataract surgeon or a refractive surgeon who performs LASIK, PRK and other vision correction procedures, I recommend you do so.

— Dr. Heiting

Q: At what age does astigmatism usually occur? I’ve been wearing glasses since I was about 9 or 10, and I started wearing contacts at 16. I’m 22 now. In the past couple of years I’ve been told that I have astigmatism. — Alex, Georgia

A: Astigmatism often begins in early childhood, but it can occur at any age. Sometimes, wearing contact lenses can cause astigmatism, especially if the amount of oxygen reaching your corneas is significantly reduced for extended periods. This contact lens-induced astigmatism usually is temporary, but it could possibly be permanent.

If your astigmatism continues to change, ask your eye doctor if your contact lens wear might be a factor, and if you should try a different type of lens or cut back on how long you wear your lenses. — Dr. Heiting

For answers to questions about astigmatism and contact lenses, see our Contact Lenses for Astigmatism Q&A page.

Please note: If you have an urgent question about your eye health, contact your eye care practitioner immediately. This page is designed to provide general information about vision, vision care and vision correction. It is not intended to provide medical advice. If you suspect that you have a vision problem or a condition that requires attention, consult with an eye care professional for advice on the treatment of your own specific condition and for your own particular needs. For more information, read our Terms of Use.

Page updated October 2017

Find an eye doctor near you.

All About Astigmatism

Astigmatism is a term that most of us have heard, but few really know what it refers to (it is also commonly mispronounced as “an astigmatism,” instead of “astigmatism”).Technically speaking, astigmatism is an imperfection in the curvature of the eye’s cornea or lens. Simply put, astigmatism means that the eye isn’t completely round.

Perfectly spherical eyes are round and smooth like ping pong balls. A spherical cornea and lens will focus incoming light directly on the retina creating crisp, clear images. A cornea or lens with astigmatism has an oblong shape, similar to a football. When you have a non-spherical cornea or lens, some areas are steeper or more rounded than others, so light rays are prevented from meeting at a common focus. This results in distorted images.

Common Symptoms Of Astigmatism

Astigmatism is so common that almost all of us have it to some degree. The causes are predominantly genetic, and can increase or decrease with age. Outside factors like surgery, eye disease, or an injury can also cause you to develop an astigmatism.

With the naked eye, you likely won’t notice an astigmatism in your eye or in the eyes of others. Just like nearsightedness or farsightedness, astigmatism isn’t a “visible” condition. That said, there are some common symptoms that may be signs of astigmatism, such as:

  • Blurry vision
  • Eye strain
  • Squinting to see near or far images
  • Difficulty focusing on printed words
  • Double vision
  • Headaches

If you’re experiencing any of these symptoms, you should make an appointment with your eye doctor to get tested for astigmatism.

Image source: Kowa Optimed Eye Care

How To Diagnose Astigmatism

In order to determine if you have astigmatism, your eye doctor will perform a comprehensive eye exam by measuring how effectively your eyes can focus light. Several things that he/she will test include:

  • Visual acuity — this is the basic vision test that we are most familiar with where you read a series of letters on a distance chart. A result of 20/20 means perfect vision, while a visual acuity of 20/40 means you would have to be 20 feet away to clearly read a letter that should be visible at 40 feet away.
  • Keratometry — this type of test is used to measure the curvature of your cornea by focusing a circle of light on your cornea and measuring its reflection.
  • Refraction — using a phoropter, your doctor places a series of lenses in front of your eyes to measure how they focus light. The power of the lenses is adjusted to determine the measurement of corrective lenses that would give you the clearest vision. The final measurement is used to provide an eyeglass or contact lens prescription that corrects for nearsightedness, farsightedness, and astigmatism.

Reading Astigmatism Correction On Your Prescription

If you have an astigmatism correction on your prescription, you’ll have both CYL and AXIS values for one or both eyes. You’ll see a minus (-) or plus (+) number in the CYL section (If your eye doctor gave you a handwritten prescription, the CYL section would be the second series of numbers followed by the AXIS.).

The AXIS number represents the degree of the angle at which the cylinder is placed on your corrective lenses. Your AXIS number will be a whole number between 1 and 180. For example, if your AXIS number is 180 then your astigmatism is corrected by placing the cylinder horizontally on your lens. Many people’s prescriptions fall in between these right angles, but most commonly near 180 or 90 degrees.
Tip: If you don’t see a number in the AXIS field, but have a CYL value, contact your eye doctor since this is likely an error.

When you look at the AXIS number on your prescription, you may notice some zeroes before the number, such as 005 or 090. This translates to AXIS numbers of 5 and 90. The zeroes are there for clarity, to easily distinguish between, say, 009 and 090.

Ordering Glasses Using Your Astigmatism Prescription

The highest CYL number that we can correct at Zenni is +/-6.00. Since the majority of the lenses we offer accommodate this CYL correction, you have plenty of frame options to choose from.

There is an extra-strength charge on orders of single-vision lenses when the prescription indicates a strong astigmatism, since these are more complicated to produce. Bifocal or progressive lenses with high CYL numbers that call for strong astigmatism corrections do not have any extra charges.

If you’re in the market for some new frames that can accommodate astigmatism corrections, discover our latest styles here.

Astigmatism – How Severe is Yours?

Astigmatism is a Greek word meaning “not like a dot”. The name of this refractive error comes from the fact that astigmatic people can see dots like a line.
This is true for moderate to severe astigmatism, since a survey of normal eyes shows that almost every human eye has a baseline corneal astigmatism of at least 0.25 to 0.50 diopters- in other words a small bit of mild astigmatism is very common and needs no treatment at all.
Astigmatism exceeding 1 dioptre is about 20%-30% among the general population, and does need treatment. Optilase offer a free consultation to patients to see if they may be a good candidate for Laser Eye Surgery in order to treat astigmatism and any accompanying refractive errors, in order to eliminate dependence on corrective eyewear.

Oddly-Shaped Cornea causes Vision Problems

In order to have clear vision, the cornea has to have a smooth surface and curvature; ideally a perfect sphere.
In people who have astigmatism, natural corneal curvature is distorted in a meridian (egg shape). This distorted corneal meridian(s) scatter(s) light rays. In other words, an astigmatic eye bends light rays different at different meridians, resulting in many images with many focal points (inability to focus on a single plane).

Blurry Vision all the Time

This causes blurry, ghosted, or smeary-looking vision. If you examine the image focused by an astigmatic eye on its retina, you may notice many superposed off-focus images on a well-focused image. The eye behaves like a dodgy camera and it can be quite exhausting for the sufferer. Of course, people with astigmatism have a constant blur for both near and distant vision.
Sometimes astigmatism may not stem from the cornea but from the lens or from other refractive media in the eye- this isn’t very common and will easily be diagnosed either by your own eye doctor is you wear corrective eyewear, or by the Optilase team if you haven’t been diagnosed before.

Different Degrees of Severity

The severity of astigmatism can be classified as follows:
Mild Astigmatism 3.00 dioptres
Astigmatic people may suffer from headaches, tired eyes and sensitivity to bright lights. Sometimes, like near-sighted people, they may squint in order to improve their vision.
Just call Optilase on 1890 301 302 to book a free consultation, and see if you might be a candidate for Laser Eye Surgery, to say goodbye to your astigmatism and your corrective eyewear for ever.

How Is Astigmatism Treated?

Your eye doctor can correct it with glasses, contact lenses, or surgery. But some doctors believe very small amounts of astigmatism are best left untreated.

Eyeglass lenses are curved to counteract the shape of the cornea or lens that’s causing blurred vision. They work well when you look straight ahead. But depending on how much correction you need, they might make the floor or walls look tilted. This should go away as you get used to them. If you have severe astigmatism it might take a week or so. If your sight doesn’t get better, ask your doctor to recheck your prescription.

Contact lenses can also help, but you’ll need a special pair. All contacts rotate when you blink. The soft lenses used for astigmatism, called toric lenses, are designed to return to the same spot each time. Rigid (hard) gas permeable contact lenses are a better choice if your astigmatism is severe.

Laser eye surgery ( LASIK ) reshapes your cornea so it can focus light rays better. The doctor numbs your eye with drops, then uses a sterile mechanical device (or another laser) to create a thin flap on your cornea. He pulls it back with a tiny tool to expose the central layers of your cornea. He’ll use a laser to sculpt them. Then he returns the flap to its original position. Finally, he’ll give you anti-inflammatory and antibiotic eyedrops. Once he covers your eyes with transparent shields, you’re ready to go home.

The cost ranges from $700-$3,500 per eye. Because you choose to get the procedure to replace your eyeglasses, LASIK is rarely covered by health insurance.

Most people who have LASIK are happy with the results. But there are some potential downsides to LASIK:

  • The procedure could over- or under-correct your vision, which will require follow-up surgery.
  • You may see a glare around lights at night. But new procedures and screening tests are designed to minimize glare.
  • You may have increased eye dryness.
  • If you’re age 40 or older, you may still have to wear reading glasses. You can avoid this with a monovision technique that focuses one eye for distance and the other eye for near vision. You might think this would be confusing, but most people adjust easily. You can wear contact lenses or handheld lenses to see what it’ll be like before you get the surgery.

Astigmatic keratotomy, or limbal relaxing incisions, is another option. The surgeon makes tiny cuts on the steepest curves of your cornea. This lets light focus more precisely on your retina. If you have more severe astigmatism, you may have laser surgery instead.

Astigmatism

What is Astigmatism?

Astigmatism usually occurs when the front surface of your eye, the cornea, has an irregular curvature. Astigmatism is one of a group of eye conditions known as refractive errors and these errors cause a disturbance in the way that light rays are focused within your eye. Astigmatism often occurs with nearsightedness and farsightedness, conditions also resulting from refractive errors. Astigmatism is not a disease nor does it mean that you have “bad eyes.” It simply means that you have a variation or disturbance in the shape of your cornea.

Symptoms

  • Distortion or blurring of images at all distances
  • Headache and fatigue
  • Squinting and eye discomfort or irritation

The symptoms described above may not necessarily mean that you have astigmatism. However, if you experience one or more of these symptoms, contact your ophthalmologist for a complete exam.

Causes

Normally, the cornea is smooth and equally curved in all directions and light entering the cornea is focused equally on all planes or in all directions. In astigmatism, the front surface of the cornea is curved more in one direction than in the other. This abnormality may result in vision that is much like looking into a distorted, wavy mirror. The distortion results because of an inability of the eye to focus light rays to a single point.

If the corneal surface has a high degree of variation in its curvature, light refraction may be impaired to the degree that corrective lenses are needed to help focus light rays better. At any time, only a small proportion of the rays are focused and the remainder are not, so that the image formed is always blurred. Usually, astigmatism causes blurred vision at all distances.

Risk Factors

A small amount of astigmatism is very common and the tendency to develop astigmatism is inherited. A larger amount of astigmatism can be associated with diseases such as keratoconus.

Tests and Diagnosis

The amount of astigmatism in the eye can be measured in various ways. The autorefraction or the subjective refraction—based on the patient’s response—that are done at the beginning of an eye exam is one way to measure astigmatism. The amount of astigmatism caused by the cornea is measured in the clinic by a diagnostic instrument called a keratometer.

Treatment and Drugs

If the degree of astigmatism is slight and there are no other problems of refraction, such as nearsightedness or farsightedness, corrective lenses may not be needed. If the degree of astigmatism is great enough to cause eye strain, headache, or distortion of vision, corrective lenses will be needed for clear and comfortable vision.

The corrective lenses needed for astigmatism are called toric lenses and they have an additional power element called a cylinder. They have greater light-bending power in one axis than in others. Your ophthalmologist will perform precise tests during your exam to determine the ideal lens prescription. Refractive surgery also may be an option for correcting some forms of astigmatism.

Astigmatism may increase slowly. Regular eye care can help to insure that proper vision is maintained. You may have to adjust to wearing eyeglasses or contact lenses if you do not wear them now. Other than that, astigmatism probably will not significantly affect your lifestyle.

Find a Doctor or Location

  • Find a Doctor
  • Find a location
  • Call 734-764-4190

Reviewed by Jill E. Bixler, M.D.

About the author

Leave a Reply

Your email address will not be published. Required fields are marked *