What is astigmatism?

Young woman squints while looking at laptop screen

Do you experience blurriness, especially when driving at night, constant eye strain or headaches that you just can't seem to shake? You could be suffering from an eye condition known as astigmatism - an extremely common and usually minor eye problem that's often present at birth, and causes unclear vision due to an irregularly-shaped cornea. In fact, there're an estimated 800,000 people living with astigmatism across the United Kingdom.

But can this eye condition be developed at a later stage in life, how do you go about treating it, and what exactly causes it? Not to worry, as we've got all the answers to your astigmatism-related queries below.

What causes astigmatism?

Graphic showing the difference between a spheric eye and one with astigmatism

As we've mentioned, many people are often born with astigmatism, but in some cases, it can occur after an eye injury, operation or disease. This eye condition or refractive error is caused when your eye isn't completely round, meaning it looks more like a rugby ball than a football. If the shape of your cornea is irregular like this then the light is bent in more than one direction, so objects appear blurry and not fully in focus.

Astigmatism usually occurs alongside other refractive eye conditions like myopia (short-sightedness) and hyperopia (long-sightedness), which result in your eyes incorrectly bending light rays. The rare condition, keratoconus, can also alter the clear front part of your eye, making it more cone-shaped and causing astigmatism to occur. Contrary to popular belief, you can't develop or worsen astigmatism by sitting too close to your television or reading in poor lighting.

The two main and most common types of astigmatism are:

  • Regular astigmatism - the cornea is curved more in one direction than the other.
  • Irregular astigmatism - the curvature of the cornea isn't even across the eye, and can curve in multiple directions or be steeper in shape towards the bottom.

Symptoms of astigmatism

Those suffering from astigmatism can experience varying symptoms, depending on the severity of their condition.

The most common astigmatism symptoms include:

  • Blurred vision
  • Headaches
  • Eyes strain
  • Squinting
  • Night blindness
  • Double vision
  • Fatigue
  • Irritation of the eyes

It's also possible to have astigmatism and not encounter any of these symptoms, which is why regular eye tests are so necessary - most optometrists recommend having an eye test at least every two years. If untreated correctly, the symptoms of astigmatism will worsen over time, and driving at night or in low light conditions can be especially dangerous.

Astigmatism and contact lenses

The good news is that astigmatism is often easily correctable, particularly if it's detected early on. If you're found to be astigmatic, the most practical, convenient and cost-effective option to rectify it is with toric contact lenses. Differing from normal contact lenses and designed in a torus (doughnut-like) shape, these typically soft lenses can easily bend and adapt, assisting your eyes in focusing on light, and ensuring that your vision is crisp and clear.

Unlike regular lenses, toric lenses also encompass different powers, helping to alter the varying degrees of sightedness experienced by those with hyperopia and/or myopia. Additionally, toric lenses are formed in such a way that they can rotate position to adjust accordingly to line up with your eye. Available in daily disposables, two-weeklies or monthlies and paired with eye drops for further comfort, toric lenses can enhance the quality of life for all astigmatism sufferers. Consult your optometrist to find out what would work best for you - and check out our eye care centre for helpful tips and how-to guides, such as a roundup of the best contact lenses for astigmatism.

Alternative astigmatism treatments

Corrective eyewear and specifically-designed glasses is another treatment option in terms of remedying astigmatism, and a more permanent solution to fix severe cases of astigmatism is refractive surgery. Amending the refractive state of the eye, this non-essential surgery means that you don't have to depend on lenses or glasses going forward. The process differs according to the patient, but usually involves lens implantation, surgical remodelling of the cornea lens or a lens replacement.

Astigmatism in children

Given that astigmatism is often present at birth, taking your child for annual eye tests is strongly recommended. Depending on the age of your child, your optician will be able to advise on suitable treatments if this condition or any other eye health problems are identified. Particularly in young children, high astigmatism may cause amblyopia (lazy eye), where the brain pays more attention to one eye, making recurring eye examinations even more important.