The National Eye Institute (NEI) aims to help patients and families to be more knowledgeable and aware about various eye conditions by providing relevant information that could help answer some questions.
Here are some common questions about astigmatism and research-based information developed by the NEI.
What is astigmatism?
Astigmatism is a common type of refractive error. It is a condition in which the eye does not focus light evenly onto the retina, the light-sensitive tissue at the back of the eye.
What is refraction?
Refraction is the bending of light as it passes through one object to another. Vision occurs when light rays are bent (refracted) as they pass through the cornea and the lens. The light is then focused on the retina. The retina converts the light-rays into messages that are sent through the optic nerve to the brain. The brain interprets these messages into the images we see.
How does astigmatism occur?
Astigmatism occurs when light is bent differently depending on where it strikes the cornea and passes through the eyeball. The cornea of a normal eye is curved like a basketball, with the same degree of roundness in all areas. An eye with astigmatism has a cornea that is curved more like a football, with some areas that are steeper or more rounded than others. This can cause images to appear blurry and stretched out.
Who is at risk for astigmatism?
Astigmatism can affect both children and adults. Some patients with slight astigmatism will not notice much change in their vision. It is important to have eye examinations at regular intervals in order to detect any astigmatism early on for children.
What are the signs and symptoms of astigmatism?
Signs and symptoms include:
- Headaches
- Eyestrain
- Squinting
- Distorted or blurred vision at all distances
- Difficulty driving at night
If you experience any of these symptoms, visit your eye care professional. If you wear glasses or contact lenses and still have these issues, a new prescription might be needed.
How is astigmatism corrected?
Astigmatism can be corrected with eyeglasses, contact lenses, or surgery. Individual lifestyles affect the way astigmatism is treated.
