Astigmatism is an imperfection in the curvature of the eye. In a normal eye, the cornea is round like a football, whereas an astigmatic eye is shaped more like a rugby ball, with one direction more curved than the other. Due to a change in corneal curvature, the path of light entering the eye changes, disrupting image formation at the back of the eye and causing blurry vision.
Astigmatism often occurs alongside other refractive errors such as myopia (nearsightedness) and hyperopia (farsightedness) and may also occur in people with presbyopia (age-related farsightedness), resulting in blurry vision at all distances. In this article, learn more about astigmatism, including its symptoms and ways to correct this condition.
How Does it Affect Vision?
The uneven curvature of the cornea causes light to focus at multiple points rather than a single point on the retina. As a result, affected people get blurry or distorted vision.
Types of Astigmatism
The two main types of astigmatism are:
Corneal: This is the most common type of eye astigmatism, in which the cornea is unevenly curved.
Lenticular: In this type of astigmatism, the lens in the eye is irregularly shaped, leading to vision issues.
Based on severity, astigmatism can also be categorised into:
- Mild: Less than 1 dioptres. People falling in this level usually can manage without vision correction and only require correction if they experience symptoms.
- Moderate: 1 to 2 dioptres. People under this level may experience symptoms, such as blurriness.
- High: 2 to 3 dioptres. This level causes noticeable symptoms such as blurriness, headache and eye strain.
- Very high: More than 3 dioptres. In this level, people face constant blurriness followed by other symptoms.
How Common is Astigmatism?
According to the World Health Organization (WHO ), uncorrected refractive errors — including astigmatism — account for approximately 88.4 million cases of vision impairment worldwide. It is also one of the most common vision disorders in the UK. A study conducted in the UK on over 83,000 adults (aged 40 to 69) found that nearly 69% had detectable corneal astigmatism and 29% were found to have clinically significant levels of corneal astigmatism. This shows how common astigmatism is among the general population.
What Causes Astigmatism?
It is mostly present at birth and influenced by genetics. However, there are many other factors that can cause astigmatism, including:
Keratoconus: This progressive eye condition causes the cornea to thin and bulge out, changing its shape to a cone-like structure, leading to astigmatism.
Eye Trauma or Injury: A hard blow or trauma to the eye caused by a ball or any flying object can alter the shape of the cornea. Such injuries can also lead to astigmatism.
Eye Surgery: Some surgical procedures, such as cataract surgery, may alter the shape of the cornea, although modern techniques minimise this risk.
Signs and Symptoms of Astigmatism You Shouldn’t Ignore
While blurry vision is the most common symptom of this eye condition, other symptoms may include:
- Headaches
- Eye strain
- Increased halos or glare around lights, particularly at night
- Squinting to see clearly
Consult an optician if you experience any of these symptoms, who can assess your vision and discuss appropriate management options.
Is Astigmatism Manageable?
Yes, astigmatism is manageable, but it is not considered curable. The management or correction of this condition depends on the level of astigmatism you have, for instance, mild, moderate or severe, your symptoms and lifestyle needs. Your optician can advise you on the most suitable options for correction, including:
Prescription Glasses: This can be an affordable way to correct blurry vision. These prescription glasses feature a cylindrical (toric) lens design to compensate for the irregular curve of the cornea or lens. They improve visual clarity by directing light to focus correctly on the retina.
Toric Contact Lenses: Toric contact lenses for astigmatism are very common and can be found in various modalities, including daily, weekly and monthly. These contact lenses for astigmatism feature different optical powers across specific meridians and are designed to stay stable on the eye to ensure clear vision.
Laser or Refractive Eye Surgery: Procedures such as LASIK use laser technology to reshape the cornea, reducing astigmatism and improving vision.
There is no one-size-fits-all solution for astigmatism. The best way to correct astigmatism is to choose an option that suits your eye health, lifestyle and vision needs.
Frequently Asked Questions
Is astigmatism serious?
Most of the time, astigmatism is not a serious eye condition. But if left uncorrected, it can cause eye strain and headache. It is always good to consult your optician for an eye health check.
Is astigmatism genetic?
Yes, astigmatism often has a genetic link. However, this condition can also be caused by an eye injury, post-surgery complications or other factors.
Can astigmatism get worse with age?
Astigmatism can change over time as the cornea or lens naturally changes, including age-related changes in the lens, such as those caused by cataracts.
Will astigmatism cause blindness?
No, astigmatism alone doesn’t cause blindness. It is a common refractive error, which can be effectively corrected using glasses, contact lenses and in some cases, surgery.
Disclaimer: The advice in this article is for informational purposes only and does not replace medical care or an in-person check-up. Please check with an eye care professional before purchasing any products or remedies. For information on our article review process, please refer to our Editorial Policy.
Tina Patel is a qualified Contact Lens Optician at Feel Good Contacts with over 25 years of experience in the optical industry. She is a member of ABDO and registered with the GOC. Tina holds a BSc. (Hons) in Optical Management from Anglia Ruskin University and qualified as a Dispensing Optician in 2002. In 2007, she further specialised by completing advanced training in contact lenses, gaining her qualification as a Contact Lens Optician. She now shares her clinical expertise through teaching at City, University of London, guiding future opticians.
