What is Astigmatism? Causes, Symptoms & More
Astigmatism is a common condition that can result in blurred or distorted vision at all distances, varying with the strength of the astigmatism. It occurs when the cornea or lens is not a perfectly curved shape. It is also a more common condition than you may think. In the UK, 47% of people who wear glasses have astigmatism to some degree.
Astigmatism can also affect people at any age and often people with astigmatism are short-sighted or long-sighted as well.
If left uncorrected, astigmatism can lead to headaches, fatigue, squinting and pain in the muscles around your eye. The blurry vision people experience with astigmatism is caused by the inability of the eye to focus the light entering the eye on to the retina. People with astigmatism may see the blurred image on the left, where the eye is unable to focus the image correctly. When using vision correction in the form of glasses or contact lenses then the eye is able to focus the light entering the eye, the result being a much clearer, focused image as seen on the right.
If you have astigmatism you may experience the blurred vision demonstrated in the image below.
- + Did you know there are two types of astigmatism?
There are two types of astigmatism, regular and irregular. Regular astigmatism occurs when the cornea is curved more in one direction than the other and found either in the cornea or crystalline lens. It is the most common form of astigmatism and can be corrected with glasses or toric contact lenses. It is this ‘toric’ surface of the eye that looks like a rugby ball where the optical shape of the eye leads to astigmatism.
Irregular astigmatism is far less common and happens when the curvature of the cornea isn't even across the surface of the eye. Instead of being curved mostly in one direction like a football, the eye could curve in multiple directions, or the curve could be steeper towards the bottom. Irregular astigmatism is often the result of an eye injury that causes a scar to develop on the cornea. It can't be corrected with glasses, but it may be possible to correct with contact lenses.
- + What causes astigmatism?
The images your eye transmits to your brain are only clear if rays of light passing into your eye focus on a single point on your retina, at the back of your eye.
Astigmatism is caused when either the surface of the eye (the cornea) or the lens behind it, is an irregular shape. Instead of being round, it is shaped more like a rugby ball. As a result, the light doesn’t focus correctly on the retina and the image is blurred.
- + What are the symptoms of astigmatism?
Astigmatism can cause blurred vision when you are trying to focus on activities that require you to see objects at long distances, such as road signs. It can also affect your vision for close activities, such as reading or sewing. If left uncorrected, astigmatism can lead to headaches, fatigue, squinting and pain in the muscles around your eye.
- + How do I know if I have astigmatism?
If you suspect you have astigmatism you should visit your optician and ask for an eye examination. To help you find your nearest optician please use the "find an optician"tool. Your optician will use an astigmatism chart to help determine the curvature of your cornea or lens. An abnormal curvature will sharply focus parts of the image
onto your retina, while blurring others.
Astigmatism Eye Test
Whilst you are waiting to see your optician you can take an astigmatism test at home using the image below.
- If you wear glasses or contact lenses, put them on.
- Sit about 35 cm (14 inches) away from your computer screen.
- Look at the chart with your hand covering one eye.
- How do the lines appear? (Are they all equally clear and sharp?)
- Follow these steps again to test the other eye.
What do your results mean?
If you do not have astigmatism, the lines will appear sharply focused and equally dark. You may have astigmatism if some sets of lines appear sharp and dark, while others are blurred and lighter. Whatever your result, you must get a confirmed diagnosis from an optician.
- + What astigmatism test might an optician carry out?
An optician can carry out a number of tests to help diagnose astigmatism. One of the most common methods is to check your ‘visual acuity’.
Your visual acuity is checked on a chart which is made up of both letters and numbers that the optician will ask you to read from. The letters and numbers become progressively smaller the further down the chart you go. It can also be used to test for myopia (near-sightedness) and hypermetropia (far-sightedness) as well as astigmatism.
Astigmatism can accompany either myopia or hypermetropia in around 50% of all cases and blurry vision may not be the result of astigmatism. This is why you should always seek the professional opinion of an optician.
- + How can astigmatism be corrected?
If your optician confirms you have astigmatism, don’t worry. Nearly half of the population has some form of astigmatism and it can usually be corrected with glasses or ‘toric’ contact lenses.
Soft, toric contact lenses correct astigmatism by compensating for the individual differences in the shape of your eye, enabling light to focus correctly on your retina. If you are short-sighted or long-sighted as well having astigmatism, toric contact lenses will correct these vision problems at the same time as correcting astigmatism.
Astigmatism in Children
For most people, they are born with astigmatism so it’s vitally important that your children have regular eye tests.
Often children will not realise there is anything wrong with their vision and if left undiagnosed for a number of year conditions like astigmatism can result in a lazy eye.
Undiagnosed astigmatism can also impact their development, with difficulty in reading and concentration levels.
To find out more about testing your children’s eyes, please speak to your local optician or health care professional.
Contact Lenses for Astigmatism
For clear vision with astigmatism, your contact lenses need to stay in place and not rotate or shift out of position. ACUVUE® Brand Contact Lenses for astigmatism achieve this with their unique Accelerated Stabilisation Design (ASD). ASD technology ensures that however you move your head or eyes, your vision stays stable, crisp and clear.
For ACUVUE® contact lenses with ASD technology that can be used to correct astigmatism you can choose either:
Both of these lenses are available to trial for free, you simply need to complete the "free contact lens trial"1 form here and take the certificate along to your optician’s appointment.
1. Please note professional eye test and fitting fees may apply. See full terms and conditions.
How do ACUVUE® Contact Lenses for Astigmatism work?
See how ACUVUE® Contact Lenses for Astigmatism use ASD technology and gravity to keep the contact lens in place as you move about, play sport or just go about your normal day.