Astigmatism is a type of common refractive error. It is a disorder in which the eye does not focus light evenly on the retina, the light-sensitive tissue in the back of the eye.
What is refraction?
Refraction occurs when the light changes its direction as it passes through one object to another. Vision occurs when the rays of light deviate (are refracted) as they pass through the cornea and lens. This light is then focused on the retina. The retina transforms light into electrical impulses that are sent to the brain through the optic nerve. The brain interprets these messages, making them the images we see.
Causes and Risk Factors
How does astigmatism occur?
Astigmatism occurs when the light deviates differently, depending on where it hits the cornea, and passes through the eyeball. The cornea of a normal eye has a curvature like that of a basketball. It is equally round in all areas. An eye with astigmatism has a cornea with a curvature similar to that of an American football. It has some areas more inclined or more rounded than others. This can cause the images to look blurry or elongated.
Who is at risk of having astigmatism?
Astigmatism can affect both children and adults. Some patients with mild astigmatism will not notice large changes in their vision. It is important to do regular eye exams to detect any astigmatism early in children.
Symptoms and Detection
What are the signs and symptoms of astigmatism?
Signs and symptoms include:
- Squint to see
- Distorted or blurred vision at any distance
- Difficulty driving at night
If you suffer from any of these symptoms, visit your eye doctor. If you wear glasses or contact lenses and still have these problems, you may need a new prescription.
How is astigmatism diagnosed?
Astigmatism is usually detected during a complete examination of the eyes with dilated pupils. It is important to be alert to any change in your vision. This can help detect any common vision problems. If you notice any change in your vision, visit your eye doctor for a complete eye exam with dilated pupils.
Can you have astigmatism without know it?
It is possible to have a mild astigmatism and not know it. This is especially true for children who are not aware that their vision is different from normal. Some adults may also have mild astigmatism without presenting any symptoms. It is important to have complete eye exams with dilated pupils to make sure your vision is optimal.
How is astigmatism corrected?
Astigmatism can be corrected with glasses, contact lenses or surgery. Each person’s lifestyle affects the way astigmatism is treated.
Glasses are the simplest and safest way to correct astigmatism. Your eye doctor will prescribe appropriate glasses to help you see as clearly as possible.
Contact lenses work by becoming the first refractive surface for light rays entering the eye. This results in a refraction or a more precise approach. In many cases, contact lenses provide clearer vision, a wider field of vision and greater comfort. They are a safe and effective option if they fit and are used correctly. However, contact lenses are not the best option for all people. Talk to your eye doctor to see if contact lenses are an option for you.
Refractive surgery is intended to permanently change the shape of the cornea. This change in the shape of the eye restores the ability to focus on the eye. It allows light rays to focus precisely on the retina for enhanced vision. There are many types of refractive surgeries. Your eye doctor can help you decide if surgery is an option for you.