What is astigmatism?
Astigmatism is a fairly common visual condition that makes your vision blurry at a distance. It’s usually caused when the cornea of the eye becomes an irregular shape. In order to see perfectly clearly, any object we look at needs to be uniformly in focus at the back of the eye.
Astigmatism normally occurs when either the cornea or crystalline lens of your eye (or in some cases both) are not the ideal spherical basketball shape, but more like the pointed end of a rugby ball. This means your eye focuses on light at two separate points on the retina, which is the light‑sensitive layer at the back of your eye. As a result, this can cause your vision to become blurry or distorted.
The different types of astigmatism
Understanding the different types of astigmatism can help you manage the condition better. The main types of astigmatism include:
Corneal astigmatism:
This type of astigmatism occurs when the cornea, the clear front surface of your eye is irregularly shaped, resembling a rugby ball, instead of being perfectly round. This is why you might sometimes hear people refer to astigmatism informally as ‘rugby ball or football eye’. The irregularity affects the way light is focused on the retina, leading to blurred or distorted vision.Lenticular astigmatism:
Unlike corneal astigmatism, lenticular astigmatism stems from an irregular shape of the lens inside your eye. While the cornea's shape is normal, the lens's uneven shape prevents light from focusing properly on the retina. The result is a vision distortion similar to corneal astigmatism.Myopic astigmatism:
In this type of astigmatism, one or both principal axes of the eye are nearsighted. If both axes are nearsighted but to different degrees, it's referred to as compound myopic astigmatism. If only one axis is nearsighted, it's called simple myopic astigmatism.Hyperopic astigmatism:
This occurs when one or both principal axes are farsighted. Similar to myopic astigmatism, if both axes are farsighted but to varying extents, it's known as compound hyperopic astigmatism. If only one axis is farsighted, it's called simple hyperopic astigmatism.Mixed astigmatism:
This type of astigmatism features one principal axis being nearsighted and the other farsighted. It represents a mix of myopic and hyperopic astigmatism, leading to vision that can be blurred at both near and far distances.
It’s important to note that astigmatism, in the majority of cases, can be corrected by glasses or contact lenses.
The difference between astigmatism and myopia
Astigmatism and myopia are two common vision conditions that blur your sight. However, they are not one and the same and are classed as two different refractive errors.
Astigmatism is caused by an irregularly shaped cornea or lens, leading to blurred or distorted vision at any distance.
Whereas myopia, or (short‑sightedness) makes distant objects blurry while close ones remain clear. This is due to an elongated eyeball or overly curved cornea that focuses light in front of the retina.
Causes of astigmatism
The cause of astigmatism is usually genetics – people with this condition tend to be born with it. However, there are other causes of astigmatism too. Let’s explore each one in more detail:
Astigmatism from birth:
Astigmatism is usually something you’re born with and is more common in premature or low birth weight babies. It’s not clear why it happens if you are born with it, but it’s most likely linked to your genetics and tends to be hereditary. Although lots of children are born with astigmatism, as they grow and their eyes change shape, it can improve with age.Developmental factors:
Though it’s possible to grow out of astigmatism with age, it’s also possible to develop it, too. As children grow, the shape of their corneas can change, which can lead to the development of this eye condition.Keratoconus:
More significant astigmatism is often seen if you suffer from an eye condition known as keratoconus. This is a progressive eye disease in which your cornea thins and begins to bulge into a cone‑like shape, causing astigmatism and other vision issues.Eye surgery:
Certain types of eye surgery, including cataract surgery, can alter the cornea's shape and potentially lead to astigmatism.Eye injury:
Trauma or injury to the eye can cause scarring or change the shape of the cornea, which can lead to astigmatism.Corneal scar tissue:
Scarring of the cornea from infections or ulcers can distort its shape and cause astigmatism.Contact lenses:
Improper or excessive use of certain types of contact lenses, especially rigid or hard lenses, can temporarily change the shape of the cornea and bring about astigmatism. This condition is often reversible once the use of the lenses is discontinued or properly managed.
It’s also worth noting that astigmatism is commonly found in conjunction with long or short‑sighted prescriptions and mild levels of astigmatism are very common as very few eyes are perfectly spherical. This is why regular eye tests are important because your vision can change over time for a number of reasons.
Symptoms of astigmatism
As well as blurry vision, astigmatism may give rise to a number of other symptoms. These can vary depending on the severity of condition as well as how it is treated. For instance, a person who wears glasses for astigmatism is likely to experience no symptoms in comparison to someone who does not wear glasses.
The most common symptoms of astigmatism include:
Headaches:
The extra effort needed to focus on objects when you have astigmatism can lead to frequent headaches.Squinting:
Individuals with astigmatism may find themselves squinting often in an attempt to see more clearly.Fatigue:
Due to the strain on the eyes, individuals with this eye condition may experience increased tiredness, especially after visual tasks such as reading.Eye strain:
Struggling to focus on blurred images could cause eye strain, especially after prolonged activities such as using a computer or looking at distant objects.Difficulty seeing at night:
Astigmatism can make it particularly hard to see in low light conditions or during the night, affecting the ability to drive safely after dark.
If you notice any of these symptoms, it's important to schedule an eye test. An eye care professional can diagnose astigmatism through a comprehensive eye exam and recommend the appropriate treatment options.
Diagnosing astigmatism
If you are concerned about your eyesight and think you might have astigmatism, or another eye condition, you should come in and see us as soon as possible. Our optometrists can assess your vision and recommend the best course of action.
The most effective method of diagnosing astigmatism is through a routine eye test. During your eye test your optometrist will speak to you about any concerns you have about your eyesight and will ask you to do complete a pre‑test exam which they will review afterwards.
One of these tests will include an autorefractor test, which measures the shape and focus of your eyes while you focus on a point of light.When searching for refractive errors, the autorefractor evaluates if the light reflected back from the eye focuses unevenly in different directions. If it does, this could indicate astigmatism.
Your optometrist will also perform some a mixture of subjective and objective eye tests to check your vision and eye health. Once astigmatism has been formally diagnosed, your optometrist can recommend the best option for you.
Astigmatism potential risks
Astigmatism itself is primarily a refractive error as opposed to an eye disease. However, if left undetected or untreated, it has the potential to lead to several other eye health issues or contribute to the worsening of existing conditions.
Here are some potential complications that could arise from uncorrected or poorly managed astigmatism:
Lazy eye (amblyopia)
If astigmatism is present in only one eye, then it can lead to amblyopia. This condition often occurs in children as a result of the brain favouring one eye over the other during early development stages. It’s important to get your child’s eyes early tested to ensure that they can see properly.Strabismus:
Uncorrected astigmatism in children could contribute to the development of strabismus, a condition where the eyes do not align properly when looking at an object. This misalignment can result from the unequal focusing efforts needed to compensate for blurred vision caused by astigmatism.
The symptoms of astigmatism, outlined above, such as eye strain, headaches and poor vision quality may intensify if the condition is left untreated or undiagnosed.
Treatment for astigmatism
If you’re wondering if astigmatism can be corrected through glasses, in many cases, yes, astigmatism is easily corrected through glasses, contact lenses . Let’s look at each of the treatments for this condition in more detail:
Glasses:
Glasses are often used to treat regular astigmatism (that’s when the cornea is more curved in one direction than the direction at a right angle to it). Glasses specifically tailored to the irregular shape of your cornea or lens will help provide you with a clearer and more focused vision.Contact lenses:
If your astigmatism is irregular, which tends to be more common after an eye injury or in cases of keratoconus, for example, then the cornea will be uneven and curved in numerous ways. In this case, contact lenses may be the best solution to even out the irregularities in the cornea.
Toric soft contact lenses are made with additional power in one direction specific to the prescription to correct regular astigmatism, so they can be worn like standard lenses. At Specsavers, we have several different types of toric contact lenses including Acuvue Oasys for astigmatism.
Rigid gas permeable lenses can also correct both regular and irregular corneal astigmatism. For higher levels of regular corneal astigmatism and for irregular corneal astigmatism they can provide more stable vision due to them being more rigid.
Surgery:
Also known as refractive surgery, laser eye surgery corrects focusing problems by reshaping the cornea (the transparent ‘window’ at the front of the eye) with a laser. See our FAQ page on laser eye surgery if you are considering treatment.
Choosing the right treatment for your astigmatism depends on various factors, including the severity of the condition, lifestyle factors, age, your overall eye health, and your personal preferences. Our eye specialists will be happy to answer any of your questions and guide you if you are unsure.
Can astigmatism be prevented?
Given the nature of this condition, there is no guaranteed way to stop astigmatism from developing. Astigmatism is primarily caused by an irregular shape of the cornea or lens in the eye, which is often a condition present from birth and influenced by genetics.
That being said, there are steps you can take to maintain your overall eye health and potentially minimise the progression of this condition, including:
Regular eye tests
Wearing protective eye wear during activities that could harm your eyes to prevent injuries that might result in astigmatism.
While these practices can support your eye health, its important to note that they cannot change a genetic predisposition to astigmatism.
Conclusion
Astigmatism is a common eye condition that affects a large portion of the population. Those with the condition will often encounter blurred vision and may also experience additional symptoms such as eye strain or discomfort, and in some cases, it can lead to further complications if not if not correctly managed.
Undergoing regular eye examinations is key to receiving an accurate diagnosis and getting the most appropriate advice when it comes to managing your astigmatism. Be sure to visit your local Specsavers for a chat with one our optometrists if you want further advice.
Astigmatism FAQs
Astigmatism can change over time as it only reflects the shape of the cornea, or the front window of your eye. In some eyes, it can change more than expected.
When the axis of the cyl changes, it simply means that the front shape of your eye has changed. A small change in this shape can often give a larger change in the axis, so this is nothing to be concerned about, providing your eyes are healthy. It may even occur over what seems like a short period of time. Your optometrist will check the health of your eyes in an eyesight examination and tell you if this reveals anything you should be concerned about. However, if you notice that the axis has changed dramatically (more than 90 degrees) you may want to clarify this with your optometrist, as a big change is unusual.
It is important to note that a degree of zero is also written as 180. A change from 180 to 10 is a change of 10 degrees, which is not a big shift if the cyl correction is higher. However, if you have a low cyl of 4 or lower, this adjustment could be critical. The cyl correction refers to the degree of astigmatism.
Yes. Advances in optical technology have led to the development of toric disposable contact lenses, which are specifically designed to correct astigmatism. These lenses provide clear vision, stability, and comfort for people with astigmatism, making them a suitable option for those seeking disposable lenses. Our optometrists can offer further advice on the best contact lenses for you.
Quite often people are born with astigmatism, but it can also develop as you get older and is quite common in those who are both long and short‑sighted.
Astigmatism may also occur as a result of eye surgery or an eye injury or eye condition ‑ particularly one affecting the cornea, such as keratoconus.
There are many types of astigmatism. The most common type is regular corneal astigmatism, which means the cornea is curved more in one direction like a rugby ball. Irregular corneal astigmatism, on the other hand, is where the cornea is curved in multiple directions.
Yes, as you get older your astigmatism can get worse, even if you wear glasses or contact lenses. The condition may evolve due to natural changes in your eye as you age, or as a result of eye surgery, injuries, or diseases that affect the eye's shape. Genetic factors could also play a role in how your astigmatism changes over time.
As well as this, sometimes astigmatism can be induced due to pressure on the eyeball from eyelid problems such as large eyelid cysts or infected glands. However, once these are removed, the astigmatism will usually reduce.
Yes, astigmatism can make it tricky to drive at night even with glasses or contact lenses to correct your astigmatism. For more information on how astigmatism can impact your driving at night, check out our helpful guide.
Yes, in fact this is quite common. You can be short‑sighted (myopic) and have astigmatism at the same time.
When a person has both conditions, their eye is not only elongated, causing myopia, but also irregularly shaped, causing astigmatism. Corrective lenses can help correct both conditions at the same time.
Yes, you can be long‑sighted (hyperopic) and have astigmatism. When someone has both conditions, their eye shape causes difficulty focusing on close objects due to hyperopia, while the irregular curvature of the cornea leads to astigmatism. Corrective measures, such as prescription glasses or contact lenses, can correct both conditions.
Astigmatism is measured in units of dioptres. However, in your prescription you may notice an axis box. This is an indication in which way the astigmatism is oriented. This helps your optometrist to prescribe corrective wear, as it can measure the light coming into the eye from different directions. It refers to the location where correction for astigmatism will be required on the lens.
There are two planes in astigmatism ‑ one is a vertical meridian and the other a horizontal one. The axis of astigmatism is calculated by determining the difference between these planes. Dioptre is the way an optometrist measures the power correction required, whether that be for long or short‑sightedness.
You may also notice another measurement on your prescription for cyl. This stands for cylinder and is the difference in power between the two planes of astigmatism. If there is no cyl in your prescription it means that either you have no astigmatism or that it is so slight it does not need to be corrected. It is also worthwhile noting that your prescription will be different for contact lenses and glasses, as the axis will change to reflect how close the lens is to your eye.
Some people may find that glasses make the walls or floor appear to tilt. However, this feeling usually disappears when they get used to their new glasses. In cases of severe astigmatism, this can take a week or so.
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