Distinguishing Vision Problems
When your optometrist determines your prescription for eyeglasses or contact lenses at a routine eye exam, many variables can affect your sight. Anything from dry eye to a poor night’s sleep can make your vision blurry or uncomfortable. But significant vision changes are commonly related to refractive errors.
While there are 4 refractive error types, the most common are astigmatism and myopia. Yet, it’s possible to have both types. So how are astigmatism and myopia different?
What is a Refractive Error?
Astigmatism and myopia are both refractive errors. A refractive error is a vision problem caused by irregularly shaped eye structures, either the eyeball size or an internal structure. While every part of your eye has a unique purpose, the many parts work together to detect and transmit visual information. Therefore, when one component has an atypical shape, it affects the function or eye health.
Most refractive errors, including astigmatism, myopia (nearsightedness), and hyperopia (farsightedness), tend to develop in childhood as the eye grows. Presbyopia is the only refractive error associated with aging, as natural changes to the eye’s lens cause noticeable close-vision problems over age 40.
What Is Astigmatism?
Astigmatism occurs when the eye’s cornea or lens is shaped irregularly. The 2 types are therefore called corneal astigmatism and lenticular astigmatism. The eye structures have mismatched curves instead of a smooth surface. Additionally, the shape is nonspherical, meaning the eye is more football-shaped than baseball-shaped.
Imagine looking out a window. When the glass is flat and smooth, light can pass through more easily. However, when the glass surface is bumpy or unusually curved, it changes how light enters the window and results in uneven light distribution.
Many people have some amount of astigmatism, as having a perfectly round or smooth eye shape is uncommon. Astigmatism occurs in about every 1 in 3 people. However, a person with minor astigmatism may have minimal vision problems. People with moderate to high levels of astigmatism usually require vision correction to see comfortably.
Astigmatism can occur with myopia or hyperopia, as the unusual eye shape can result in vision problems at multiple focusing distances. Untreated astigmatism can cause:
- Blurry vision (near or far)
- Difficulty seeing at night
- Eye irritation
- Eyestrain
- Headaches
- Squinting (to support focus)
Eye doctors can treat astigmatism with standard glasses, but fitting soft contact lenses can be more challenging. To achieve comfortable vision correction, patients with astigmatism may require rigid gas permeable (RGP) or specialty contact lenses.
What Is Myopia?
Myopia or nearsightedness causes blurry distance vision. It occurs when the eyeball is too long, or the cornea is too curved. Myopia is a common refractive error, affecting over 30% of the US population, with health experts predicting nearly 30% of the global population to be myopic by 2050.
Similar to astigmatism, people may have low to high myopia. Low myopia may cause few vision problems, even without corrective lenses. Unlike astigmatism, myopia only affects distance vision, not close vision.
Typical symptoms of untreated myopia include:
- Blurry distance vision
- Eyestrain
- Headaches
- Squinting (to see far objects)
Moderate to high myopia can cause severe symptoms and harm eye health. Progressive or pathological myopia increases the risk of retina problems, including retinal detachment and abnormal blood vessel growth beneath the retina. The unusual growth can lead to macular degeneration.
Progressive myopia also increases the risks of cataracts and glaucoma.
Refractive errors, including myopia, begin in childhood and typically stabilize by adulthood. Myopia control uses methods to slow eye growth in children. By controlling eye elongation and cornea changes, eye doctors aim to prevent the risks of high myopia. Some standard myopia control methods include atropine eye drops, ortho k (rigid contact lenses), and multifocal soft contact lenses.
Differences Overview
Astigmatism and myopia have similarities, but there are not the same. Take a closer look at a side-by-side comparison of the differences that cause these 2 refractive errors.
Eye Shape
Astigmatism occurs because of nonspherical shape, either the cornea or lens. Myopia occurs when the eyeball is elongated, or the cornea is too steeply curved.
Vision Problems
Both astigmatism and myopia can cause blurry distance vision, but astigmatism can also cause blurry near vision. Progressive myopia can also increase the risk of eye health problems, including retina conditions, which can cause additional vision problems.
Rarity
Astigmatism is currently the most common type of refractive error, but myopia is also common. Unfortunately, global rates of myopia are on the rise, including high myopia.
Severity
Both types of refractive errors can range from low to severe. Astigmatism can also occur alongside myopia. Fitting standard soft contact lenses for people with higher astigmatism or myopia can be challenging. Still, there are options available for vision correction.
High myopia can potentially cause significant eye health problems. Managing progressive myopia is crucial for preventing severe vision problems.
Get Vision Help Today
Astigmatism and myopia can cause similar vision problems, but they require unique treatment. At Eye Care Center of Colorado Springs, we want to help you maintain good eye health and comfortable vision. We customize treatment for your vision needs, whether your vision problems are caused by astigmatism, myopia, or both!
Our compassionate team at the Eye Care Center of Colorado Springs can help you feel and look your best. Book an appointment today!
