Understanding the Different Types of Astigmatism

Vision problems, such as nearsightedness and farsightedness, can be relatively easy to correct, but what about astigmatism? The good news is it, too, can be treated with the right approach.

At Harlem VistaSite Eye Care in the Harlem neighborhood of New York City, Brittni Rodriguez, OD, and Sarah Quan, OD, are experts at diagnosing and treating all vision issues, including astigmatism. In this blog, they explain what astigmatism is and how it can be treated.

Nearsightedness, farsightedness, and astigmatism

When you see something, light enters your eye’s cornea, and your cornea bends — or refracts — the light onto the lens. As the light passes through the lens, the lens focuses it onto the retina. The impulses then travel down the optic nerve and into your brain. At least this is what happens in an eye that works perfectly.

If the curvature of your cornea or lens is not perfect, however, the light refracts and focuses badly.

Nearsightedness

If the curve of the cornea or lens is too sharp, the light focuses in front of the retina, and you are nearsighted in that eye.

Farsightedness

If the curve is too shallow, light focuses behind the retina, and you’re farsighted in that eye.

It’s possible to be nearsighted in one eye and farsighted in the other. 

Astigmatism

Besides being curved too much or too little, the cornea or lens can also be deformed. This also affects refraction and can change the way light reaches the back of your eye. Some of the light might hit the retina, and the rest may fall in front of or behind it, causing another type of blurry vision called astigmatism.

Regular glasses to fix nearsightedness (myopia) or farsightedness (hyperopia) won’t help astigmatism.

Different types of astigmatism

There are two sources of astigmatism. Distortion of the cornea — which is the outer portion of the eye — causes corneal astigmatism. Distortion of the lens — which is just inside the front of the eye — causes lenticular astigmatism.

There are also three forms of astigmatism. Myopic astigmatism is astigmatism in an eye that is nearsighted. Hyperopic astigmatism is astigmatism in an eye that is farsighted. Mixed astigmatism is astigmatism in an eye that is both nearsighted and farsighted, because light is hitting both in front of and behind the retina.  

Treatments for astigmatism

Your specific combination of farsightedness and/or nearsightedness, whether your lens, cornea, or both are affected, and how much distortion is present all affect your astigmatism and treatment options.

Dr. Rodriguez can diagnose astigmatism by closely examining your eye and evaluating your vision. If astigmatism exists, she may recommend:

Soft toric contact lenses

These can help change the way your eye refracts light and focus it on the retina as it would if your eye was correctly shaped.

LASIK surgery

Eye surgery can correct the shape of your eye, removing the need for lenses to correct astigmatism.

If you have blurry vision even when you're wearing glasses or contacts, you could have astigmatism. To get examined and to learn about your treatment options, call 646-694-9787 or book an appointment online with Harlem VistaSite Eye Care today.