What is astigmatism?
Astigmatism is a type of refractive error where the front surface of the eye (the cornea) or the lens inside the eye has an irregular curvature which causes the vision to be distorted and blurred.
For example, instead of having a round, spherical curvature like a basketball, the cornea may be elongated like a rugby ball. Light rays entering an astigmatic eye are bent unevenly. As a result, these rays do not focus at a single point on the retina, causing some parts of the image to be more out of focus than others.
There are a number of different types of astigmatism. These include:
- corneal; and
Astigmatism often occurs with near-sightedness (myopia) and far-sightedness (hypermetropia). The exact cause remains unknown; however, some common types of astigmatism seem to run in families and may be inherited. It is thought that most people have some form of astigmatism as it is rare to find perfectly shaped curves in the cornea and lens, but the defect is rarely serious. Keratoconus is a condition in which the cornea is highly astigmatic and may cause severely distorted vision.
Blurred or distorted vision, eye strain and headaches are possible symptoms of astigmatism.
There are different amounts of blur in different directions.
What your doctor can do for you
- Perform an eye examination to determine whether you have astigmatism.
- Refer you to an ophthalmologist or optometrist for correction of the astigmatism with prescription glasses or contact lenses.
- Refer you to an ophthalmologist (eye specialist) for laser eye surgery, lens surgery or corneal surgery, which can help correct certain types of astigmatism.
Last Reviewed: 14/10/2015
1. National Eye Institute. Facts about astigmatism. https://nei.nih.gov/health/astigmatism (accessed Oct 2015).
2. Mayo Clinic. Astigmatism. Jan 2014. http://www.mayoclinic.org/diseases-conditions/astigmatism/basics/definition/con-20022003 (accessed Sept 2015).
Amblyopia (lazy eye)
Amblyopia is a common cause of reduced vision in children. Amblyopia is sometimes also known as 'lazy eye'. Usually one eye is affected, but both may be affected in some cases.
Causes of unilateral vision loss are mostly preventable
Vision loss in one eye can have huge consequences for a person’s health and quality of life - yet this research shows simple interventions can stop much of that visual impairment.
Eyes in the sun
Ultraviolet radiation from the sun can damage the eyes, especially in Australia. Problems from UV exposure include sunburn to the cornea, surfer's eye (pterygium), cataracts, macular degeneration and skin cancers.
Keratoconus is an eye condition where the cornea becomes thin, resulting in distorted vision. Find out about the causes, symptoms and treatment.
Eyesight problems: when you need glasses
How is your eyesight? Find out about short-sightedness, long-sightedness and presbyopia - common conditions that affect vision.