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What is astigmatism?

Have you found yourself wondering why your vision is blurred or distorted? Do you also get eyestrain or headaches in combination with unfocused vision? These may be early signs of astigmatism. This article uncovers what astigmatism is and what causes astigmatism. If you feel you are facing any symptoms, we recommend you book an appointment with your local optician for a professional diagnosis. 

What is astigmatism, and how does it affect vision?

If your lens and cornea are not equally curved when light enters the eye, it will not be adequately refracted. Opticians refer to this as a refractive error. Astigmatism is a common eye refractive error, similar to farsightedness and nearsightedness, which can be easily corrected with glasses.

 

Astigmatism is an eye condition where the cornea is not perfectly round, so it cannot focus light evenly onto the retina in the back of the eye. The retina converts the light we see into messages sent through the optic nerve to the brain. Normal corneas are shaped like tennis balls, but if you have astigmatism, you have a more football-shaped cornea. However, due to the refractive error, your vision will be slightly blurred or distorted at all distances.

 

As shown in the image above, a healthy eye and an eye with astigmatism appear very similar. However, an eye with astigmatism has a slightly irregular lens with a different shape to a healthy eye. The extent of astigmatism will affect the blurriness in your vision, and some cases may be more severe than others. Other blurred and distorted vision symptoms include headaches, eyestrain and difficulty seeing at night. 

 

If you experience blurred vision as an adult, you should have an eye test to check for astigmatism or other visual impairments. It is, however, recommended you have a regular eye check-up at least every two years or more frequently if you suffer from an existing eye problem. 

 

For children, it’s best to have frequent eye tests to help detect any early signs of astigmatism. This is because younger children may not be aware of the visual problem or able to communicate the issue to you.

What causes Astigmatism?

The leading cause of astigmatism is the lens's or eye curvature's irregularity. People are sometimes born with astigmatism, sometimes due to genetics. Other causes of astigmatism can be induced after eye surgery, an injury, or eye disease. 

 

Usually, astigmatism can develop alongside other visual impairments such as farsightedness and nearsightedness. There is also a rare condition called Keratoconus, when your cornea tends to have more of a cone than a dome shape. This condition can also cause astigmatism, and experts believe that many may be born with this condition. However, research is still being done to explain this condition.

Different types of astigmatism

There are two main types of astigmatism:

 

  1. Corneal Astigmatism

This type of astigmatism is the most common and is caused by a misshapen cornea. 

 

  1. Lenticular Astigmatism

Similar to corneal astigmatism, this type affects your lens instead. Some people can have a well-shaped cornea but still have lenticular astigmatism.

 

However, based on how other refractive errors combine with astigmatism, there are three additional types: 

 

  • Myopic Astigmatism: Nearsightedness combined with astigmatism happens when both curves are fixated in front of the retina. 

  • Hyperopic Astigmatism: Farsightedness and astigmatism in the eye where both curves are fixated behind the retina.

  • Mixed Astigmatism: This happens when curves are both near and far-sighted.

 

Astigmatism can also be regular or irregular. Regular astigmatism is when the curves are at 90 degrees, so perpendicular. Instead, irregular astigmatism doesn’t have angles at 90 degrees.

How to do an astigmatism test

The most trusted and recommended way to check for astigmatism is to take a trip to your local optician for an eye test. The optician can identify whether or not you have astigmatism and what type of correction you may need. 

 

There are three types of tests an eye doctor can perform to check for astigmatism: 

 

  1. Refraction: During an eye test, you look at an eye chart which helps determine if you have refractive errors, like astigmatism. This particular test helps to see how your eyes can bend light.

 

  1. Keratometry: This will help measure the cornea’s curvature and determine your degree of astigmatism. This is a helpful test if you want to use contact lenses.

 

  1. Corneal topography: This can give you a detailed map and measurement of the cornea and help detect irregular astigmatism.

 

It is essential to visit your optician to diagnose your astigmatism. However, as a preliminary test before visiting your optician, you can do some basic astigmatism tests from home. These tests do not confirm your astigmatism but will indicate that you need to book an eye test.

 

There are two easy ways to do an online astigmatism test. If you already wear glasses or contact lenses, you can take the astigmatism tests while wearing either.

Astigmatism Test 1

 

  1. Position yourself 2-10 feet away from the screen.

  2. Start by closing one eye and looking carefully at the lines.

  3. Repeat this with both eyes.

 

If the lines appear to be the same colour and thickness, it is unlikely you have astigmatism. However, if there are differences, your vision is likely to be blurred, and you may have astigmatism. You should consult your eye specialist at your earliest convenience.

Astigmatism Test 2

 

 

  1. Position yourself 2-10 feet away from the screen.

  2. Start by closing one eye and looking carefully at the lines.

  3. Repeat this with both eyes.

  4. If the lines appear similarly dark, it is unlikely you have astigmatism. However, if one or more lines appear darker than the rest, you may have astigmatism and should consult your eye specialist.

How to correct astigmatism?

For almost all types of astigmatism, glasses and contact lenses can help correct your blurred vision. If your astigmatism is very mild, you may not need any glasses or contacts at all.

 

There is also surgery to help correct astigmatism, known as refractive surgery. This type of operation helps permanently reshape your cornea. There are other types of common surgeries, such as LASIK and Radial Keratotomy. You should consult an optician and eye doctor before deciding what type of correction you may need.

Glasses for astigmatism

There are various types of lens materials that can be used to help correct visual impairments. Some of the most used materials for lenses are polycarbonate, high-index, trivex and plastic.

 

The type of lens material will depend on astigmatism's severity; usually, the higher it is, the thinner your lenses should be, such as high-index lenses. High-index lenses are more expensive but are lightweight and provide accurate visual clarity. 

 

If you have mild astigmatism and your prescription is lower than 1.00, plastic lenses can be a good choice and are also more affordable than other materials. . For moderate or more severe astigmatism, you may consider investing a little more money in polycarbonate, trivex or even high-index lenses. To determine the best lens for you, your optician will clearly outline your different lens options. To find out more about how to understand your prescription, consult our short guide.

 

It’s also important to consider lens coatings when purchasing a pair of glasses for astigmatism. You want to ensure you have the best protection for your eyes and glasses. For example, try anti-reflective coating to eliminate glare and anti-scratch to prevent lens damage.

Can you wear contacts with astigmatism?

You can wear contact lenses if you have astigmatism, which will help to correct astigmatism. You can choose between soft or hard contact lenses, depending on the severity of your astigmatism. You can also use hybrid contacts for astigmatism with a hard center and softer edges. To find out more about which contact lenses are right for you, read our useful guide.

 

Conclusion

After reading this article, we hope you know more about astigmatism. If you have any doubts or questions about eye health, we recommend you consult your local opticians. With SmartBuyGlasses, you can easily find the best correction for your astigmatism with a pair of prescription glasses or contact lenses.