Astigmatism

What is Astigmatism?

From the American Academy of Ophthalmology and the American Optometric Association 

Astigmatism is a common condition that causes blurred vision. 

Normally, the cornea and lens at the front of the eye have an evenly round shape. This helps focus light rays sharply onto the retina (the part of our eye that processes light) so you can see clearly.

With astigmatism, light rays do not refract (or bend) properly as they enter the front of the eye. This is because astigmatism is caused by an irregularly curved cornea or lens that prevents light from focusing properly on the retina. In this case, vision becomes out of focus at any distance. Doctors don't know why the shape of the cornea or lens varies from person to person. But they do know the risk of getting astigmatism can be inherited (passed down from parents, or run in families).

What someone with 3 diopters (power) of astigmatism sees.

Notice how the astigmatism mostly affects the smallest letters.

Astigmatism makes it harder to see small, fine details at all distances.

Symptoms

• Blurred vision at any distance

• Eye discomfort or strain

• Headaches

• Squinting 

But without treatment, astigmatism can:

• impact a child's performance in school and sports

• lead to amblyopia (lazy eye) and vision loss (especially when the astigmatism is higher than 2.50D, or is unequal between the eyes)

How Is Astigmatism Corrected?

• Eyeglasses or contact lenses. They work by refocusing light on the retina (the part of the eye that processes light) so that you can see more clearly.

• Refractive surgery. With LASIK and other procedures, a laser reshapes the cornea to adjust how light travels through it.

• This is only performed on adults 

• There is no best way to correct your astigmatism—the most appropriate correction is one that best suits your vision needs and lifestyle. You and your ophthalmologist/optometrist can discuss your options in more detail after your exam.

Will the astigmatism keep getting worse?

• Typically astigmatism starts at a very young age, but remains stable throughout life. If your child has astigmatism and myopia (near-slightness) then it would not be unusual for the near-sighted part to become stronger every year. If there are changes to the astigmatism, then there may be an underlying eye disease called Keratoconus.