Astigmatism Symptoms Cause Diagnosis Treatment

Astigmatism is a common and usually treatable flaw in the way the eye curves which makes it hard to see both far away and up close.

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Astigmatism happens when the curves of the cornea (the front part of the eye) or the lens inside the eye don’t match up. Instead of being round like a ball, the surface is shaped like an egg. This makes it hard to see at any distance.


Astigmatism is often present at birth, and it can happen with either nearsightedness or farsightedness. Most of the time, it’s not bad enough to require action. When that happens, you can either get corrective lenses or have surgery.

You can also read: GlaucomaΒ 


Astigmatism can cause

  • blurred or distorted vision,
  • eye strain or discomfort,
  • headaches,
  • trouble seeing at night, and squinting.

When to go to the doctor:

See an eye doctor if your eye symptoms make you less likely to enjoy activities or make it hard for you to do everyday things. A doctor of optometry can tell if you have astigmatism and, if so, how bad it is. Then, he or she can tell you what you can do to fix your vision.

Young people and kids:

Children may not realize their vision is blurry, so a pediatrician, an ophthalmologist, an optometrist, or another trained screener should check for eye disease and test their vision at the following ages and times.

  • When they are young, every one to two years at well-child visits, the eye doctor, or school or public screenings.
  • When they are in school, every one to two years at well-child visits, at the eye doctor, or at school or public screenings.


Β The eye has two structures with curved surfaces that bend (refract) light onto the retina, which makes images:

  • The clear front surface of the eye, called the cornea, and the tear film.
  • The lens is a clear structure inside the eye that changes shape to help the eye focus on things close up.

Each portion of a fully developed eye has a smooth, spherical shape like a ball. This bends all light entering the cornea or lens. This puts a sharply focused image on the retina at the back of the eye.

An optical mistake

If either the cornea or the lens is shaped like an egg with two curves that don’t match, light rays don’t bend in the same way, so two different images form. When these two images overlap or mix, they make it hard to see. Astigmatism is a type of error in the way light bends.

Astigmatism happens when the cornea or lens curves more sharply in one direction than in another. If the curves of your cornea don’t match up, you have corneal astigmatism. If the curves of your lens don’t match up, you have lenticular astigmatism.

Both kinds of astigmatism can make it hard to see. A vision that is blurry may be worse in one direction more than another: horizontally, vertically, or diagonally.

Astigmatism can be present from birth, or it can develop after an eye injury, disease, or surgery. Astigmatism isn’t caused by or made worse by squinting, reading in dim light, or sitting too close to the TV.

Other errors in vision

Astigmatism can happen along with other refractive errors, such as: (myopia). This occurs when the cornea is excessively curve or the eye is too lengthy. Light misses the retina. Instead, it focuses in front of the retina, making distance vision difficult.

  • Β Looking far ahead (hyperopia). This happens when the cornea isn’t bent enough or when the eye is shorter than usual. It has the opposite effect of nearsightedness. When the eye is relaxed, light never comes into focus at the back of the eye. This makes it hard to see things that are close by.

Read more: Glaucoma Open Angle

Different kinds of squint (Astigmatism)

Astigmatism comes in two main forms:

  1. Astigmatism of the cornea. This is the most common and happens when the cornea isn’t the right shape.
  2. Astigmatism of the lens. Like the last one, but this one affects the lens. Even if a person’s cornea is in good shape, they may still have lenticular astigmatism.

But there are other types of astigmatism based on the different refractive errors:

  1. Myopic astigmatism: This is a combination of nearsightedness and astigmatism that happens when both curves are focused in front of the retina.
  2. Hyperopic astigmatism is a combination of farsightedness and astigmatism in which both curves are fixed behind the retina of the eye.
  3. Mixed astigmatism: This is when the curves are both near- and far-sighted.

Astigmatism can also be described as being regular or not. Regular astigmatism is when the curves are perpendicular to each other, at 90 degrees. On the other hand, curves at 90 degrees aren’t present in irregular astigmatism.


An eye exam can tell if someone has astigmatism. A full eye exam includes a series of tests to check the health of the eyes and refraction to find out how the eyes bend light. Your eye doctor might use different tools, shine bright lights right into your eyes, and ask you to look through different lenses. Your doctor uses these tests to look at different parts of your eyes and vision and figure out what prescription you need for glasses or contacts to give you clear vision.


The goal of treating astigmatism is to make your eyes feel better and help you see better. You can get glasses or surgery to fix your vision.

Corrective lenses

Astigmatism can be fixed by wearing glasses or contacts that correct the way your cornea or lens is shaped.

Some examples of corrective lenses are:

  • Eyeglasses. The lenses in eyeglasses help make up for the fact that the shape of each eye is different. The lenses make sure that the light bends the right way into the eye. Other refractive errors, like nearsightedness or farsightedness, can also be fixed with glasses.
  • Contact lenses. Like glasses, most astigmatism can be fixed with contact lenses. They come in many different types and styles.

Orthokeratology uses contacts. Orthokeratology involves sleeping in hard contact lenses to even out the eye shape. To maintain the improved shape, the lenses are worn less. If you stop treatment, the eye goes back to its old shape and refractive error.

When you wear contact lenses for a long time, you are more likely to get an eye infection.

Ask your eye doctor about the pros and cons, risks, and what might be best for you.

Laser eye surgery

Refractive surgery helps people see better and makes them less likely to need glasses or contacts. Laser surgery on the cornea corrects the refractive error. Doctors will check you out to see if you are a good candidate for refractive surgery before they do it.

There are several kinds of refractive surgery for astigmatism.

Laser-assisted in-situ keratomileusis (LASIK). An eye surgeon creates a thin, hinged corneal flap. After excimer laser corneal shaping, the flap is replace.

Subepithelial keratectomy with laser help (LASEK).

Instead of making a flap in the cornea, the surgeon uses a special alcohol to loosen the cornea’s thin protective cover, called the epithelium. He or she uses an excimer laser to change the shape of the cornea and then moves the epithelium back into place.

Keratectomy with photorefraction (PRK).

Similar to LASEK, the surgeon removes the epithelium. It will grow back in a way that fits the new shape of the cornea. After surgery, you might have to wear a bandage contact lens for a few days.


This is a different way to say LASEK. Instead of alcohol, the surgeon uses a special machine with a blunt blade to separate a very thin sheet of epithelium. Excimer lasers sculpt the cornea and shift the epithelium.

Small-incision lenticule extraction (SMILE).

In this latest refractive surgery, a laser creates a “lenticule” below the cornea. This changes the shape of the cornea. A little cut removes the lenticule. SMILE currently treats mild nearsightedness alone.

Other types of refractive surgery include removing clear lenses and putting contact lenses inside the eye. There is no one best way to do refractive surgery, so you shouldn’t make a choice until you’ve had a full evaluation and talked with your surgeon in depth.

Some problems that can happen after refractive surgery include:

  • Undercorrection or overcorrection of your original problem
  • Visual side effects, such as a halo or starburst around lights
  • Dry eye
  • Infection
  • Scarring on the cornea
  • Very rarely, loss of vision

Talk to your eye doctor about the risks and benefits of these procedures.

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