Decoding the astigmatism severity scale
Astigmatism sounds scary, but it's a common variation in the shape of the cornea or the lens of the eye. If you have astigmatism, your eye has an oval or egg shape instead of a regular round shape. Most people are born with astigmatism, but it's possible to develop it later in life if you have eye surgery, injure your eye, or develop an eye disease. Learn more about the astigmatism severity scale to better understand this condition.
Astigmatism severity scale explained
Introduction to astigmatism
When you look at something, the lenses in your eyes help focus light on your retinas. Each retina contains photoreceptors, AKA cells that convert light into electrical signals. These signals travel along the optic nerve until they reach your brain, helping you interpret what you see. Ta-da!
Irregularities in the shape of the cornea make it difficult to focus light on the retinas, which may interfere with your ability to see clearly. Astigmatism causes the following symptoms:
- Distorted vision
- Blurry vision
- Headaches
- Eyestrain
- Eye discomfort
If you have astigmatism, you may also squint frequently. Although squinting doesn't hurt your eyes, it's a sign that you need to see an eye care professional.
Importance of measurement
The severity of your astigmatism has a big impact on your lens requirements, so it's important to get a precise measurement. If you look at your prescription, you'll see the words cylinder and axis. The cylinder measures your degree of astigmatism, while the axis refers to the location of the astigmatism. The more your eye looks like a football, the greater your cylinder value is.
Astigmatism is classified as a refractive error, which occurs when the shape of your eye interferes with its ability to focus light. With this type of error, objects appear blurry whether you're looking at them from up close or far away.
Degrees of astigmatism
Eye care professionals use a unit of measurement known as the diopter to determine the severity of astigmatism. Based on this measurement, your astigmatism may be classified as mild, moderate, or severe.
Mild astigmatism
If the curvature of your eye measures fewer than 1.0 diopter, you have mild astigmatism. At this level, you probably won't need treatment. However, you may notice some blurriness or distortion when you look at certain objects.
Moderate astigmatism
A diopter measurement of 1.0 to 2.0 indicates moderate astigmatism. You may need glasses or contact lenses once you hit the 1.5-diopter mark. People with moderate astigmatism may experience additional symptoms, such as squinting, blurriness, distortion, and eyestrain.
Severe astigmatism
If you have a diopter measurement greater than 2.0, you have severe astigmatism. Some eye care professionals use the subcategories of "high astigmatism" and "extreme astigmatism" to further classify this refractive error. High astigmatism ranges from 2.0 to 4.0 diopters, while extreme astigmatism exceeds 4.0 diopters.
Even with corrective lenses, you may not be able to achieve 20/20 vision if you have severe astigmatism. In that case, you may want to consider refractive surgery to reshape your cornea.
Measuring astigmatism severity
Eye exams and diagnostic tools
To check for astigmatism, your eye care professional will use a keratometer to measure the curve of your cornea. A keratometer works by measuring the reflection of light, which helps your eye care professional determine if you have a refractive error. You'll also undergo a visual acuity test and a refraction test.
The visual acuity test is one of the easiest exams you'll ever complete. All you have to do is look at a chart and read the smallest row of letters and symbols that you can see clearly. The refraction test measures how light bends as it moves through your lenses and corneas.
Importance of regular eye checkups
Astigmatism may develop suddenly, or it may get worse over time. Therefore, it's important to get regular eye exams to keep abreast of any changes. If you address astigmatism early, you may even be able to prevent it from getting worse.
Keep an eye on your eye health
Astigmatism is an extremely common condition that makes it difficult to see clearly. Fortunately, many people benefit from wearing corrective lenses. If your eye care professional prescribes contacts, visit 1-800 Contacts to shop for your preferred brand.
Frequently asked questions
Can astigmatism severity change over time?
Yes, it's possible for astigmatism to get worse over time. For example, if you develop an eye condition known as keratoconus, you may develop severe astigmatism. Keratoconus occurs when you have a pyramid-shaped cornea.
Is astigmatism severity the same for both eyes?
Not necessarily. In fact, it's rare for astigmatism to have the same level of severity in both eyes. It's even possible to have astigmatism in one eye and not the other. Ahh, the wonders of the human body. This is because the cornea in your left eye may be a different shape than the cornea in your right eye.
What are the treatment options for different degrees of astigmatism?
Corrective lenses are helpful for cases of mild to moderate astigmatism. If you have severe astigmatism, you may need refractive surgery. A refractive procedure changes the shape of the cornea, making it easier for your eyes to focus light.