Astigmatism is one of those words that gets thrown around the eye doctor’s office like it’s common knowledge. With its strange name, it’s sometimes incorrectly referred to as astigma eyes or stigmatism. But what exactly is astigmatism? This article will review the astigmatism definition and much more.
What Is Astigmatism?
Refractive errors are a group of conditions that affect how light refracts when entering the eye. Astigmatism is a common type of refractive error, like hyperopia, myopia, and presbyopia. Astigmatism distorts vision at both distance and near. It is often present in combination with myopia (nearsightedness) or hyperopia (farsightedness). Presbyopia is a condition that develops later in life, generally in one’s 40s, and causes difficulties with near vision. An eye can only be myopic or hyperopic, not both. However, presbyopia occurs with myopia, hyperopia, or astigmatism.
Symptoms of astigmatism can be, but are not limited to:
- Blurred Vision;
- Eye Strain;
When to See a Doctor
Although these symptoms may not always be a sign of astigmatism, you should see your doctor if they begin to interfere with your daily activities, including difficulty with reading, driving, or struggling with vision at any distance. An eye exam at a certified eye doctor’s office is the best strategy to diagnose astigmatism of the cornea or lens.
Astigmatism in Children
It may be harder to spot the symptoms of astigmatism in children, as they do not always recognize vision problems. If your child is struggling in school or shows signs of eye strain, it may be due to difficulty seeing clearly. This is why it is so important for children to have eye exams at the following stages:
- Before school age;
- Every 1-2 years during school age.
A licensed pediatrician, optometrist, or ophthalmologist can correctly diagnose eye astigmatism in children and help your child see the world clearly.
Factors Increasing Risk of Astigmatism
Astigmatism is a common condition, but certain factors may put you at a higher risk for this eye condition. If you have a family history of astigmatism, you should convey this to your eye doctor, as this highly increases the likelihood that you may have astigmatism as well. You may also develop astigmatism if you already have a refractive error.
Factors that increase the risk for astigmatism include:
- A family history of astigmatism;
- Myopia (nearsightedness), particularly if the prescription is extremely high;
- Hyperopia (farsightedness), particularly if the prescription is extremely high;
- Mother smoked during pregnancy;
- Black of Hispanic ethnicity;
- History of eye surgery, such as cataract surgery.
What Do People with Astigmatism See?
Due to the irregular shape of the cornea, light can not properly focus on the retina. When this occurs, only one part of the object being looked at will be in focus, causing things to look blurry and wavy. Some people who have astigmatism experience eye strain rather than blur, while others may experience both.
What Causes Astigmatism?
Astigmatism is caused by an irregular shape of the cornea or the lens of the eye. For optimal vision, light needs to enter the eye and fall on the retina in a single focal point. When you have an astigmatism, the light will fall in two separate spots, creating two focal points and causing blurred vision and distortion of images.
How Common Is Astigmatism?
Astigmatism is extremely common, about a third of the population has some form of astigmatic vision. With the proper corrective lenses, you can easily address blurred vision resulting from astigmatism.
Getting an Astigmatism Diagnosis
How is astigmatism diagnosed? A comprehensive eye exam will test for a number of things including diagnosing astigmatism. Your eye doctor will use the following tests to determine whether you have astigmatism and how to best treat it:
- Visual acuity;
Visual Acuity Assessment Test
Visual acuity measures the eye’s ability to see details from a distance. This vision test will require you to read letters from a chart to determine how well you can discern detailed shapes from far away.
For a refraction test, your eye doctor will use an instrument called a lensometer to find the right corrective lenses for you. The doctor will try corrective lenses of different strengths until you are able to see the chart clearly.
Keratotomy refers to the curve of the cornea, which can determine the degree of astigmatism. Your eye doctor will use an instrument called a keratometer to measure this.
How to Read an Astigmatism Eye Prescription
If you’ve ever looked at your prescription, you’ve seen what looks like a table with different numbers. Your astigmatism is also indicated, measured in diopters, and listed in the “cylinder” and “axis” columns.
The cylinder column on the prescription tells you how strong your astigmatism is, while the axis column tells your eye doctor exactly where the astigmatism is on your cornea. 1.5 is considered a high enough diopter value that you will need corrective lenses for astigmatism. A diopter of 0 means you do not have astigmatism.
Can You Prevent Astigmatism?
Unfortunately, there is no way to prevent astigmatism. While preventing astigmatism is impossible, getting an annual eye exam will ensure that you can manage any eye condition that you may have.
As with any eye condition, there are several options for addressing astigmatism. Let’s take a look at some of those options.
- Glasses: Corrective glasses are the most common way to treat astigmatism. Astigmatism glasses look just like any other glasses. In cases of unusually high astigmatism, the edges of the glasses can appear thick. Glasses are only able to correct regular astigmatism, not irregular.
- Toric contact lenses: Contacts for astigmatism are another option. Most people use the soft type, which can only correct regular astigmatism. The term “toric” is used to describe contact lenses that provide astigmatic correction.
- Gas permeable contact lenses: Sometimes, rigid gas-permeable lenses may be a better option than soft lenses, particularly in the rare case of irregular astigmatism. Traditional gas-permeable contact lenses are used during the day and taken out at night.
- Hybrid contact lenses: These lenses combine the rigidity of gas permeable lenses and the softness of toric lenses. They are harder in the center and become softer at the edges like a toric astigmatism lens.
If you’re looking to permanently treat your astigmatism, then you’ll want to consider refractive surgery. There are several procedures available to treat astigmatism but they are only able to correct astigmatism that comes from the cornea, not the lens. Part of your initial screening exam will determine the source of your astigmatism. Here are some of your options:
Laser-assisted in situ keratomileusis (LASIK) is the most common refractive surgical procedure, followed by photorefractive keratectomy (PRK). The main benefit of LASIK for astigmatism is that it offers a quick recovery. In LASIK, the surgeon creates a thin flap on the cornea, lifts it, and applies a laser to reshape the corneal tissue. The flap is then replaced and smoothed out. The recovery process is very quick after LASIK, as the flap helps to naturally protect the eye as it heals. Because of the quick and predictable healing after LASIK, both eyes are usually treated at the same time.
After their initial screening, some people may be found to be better candidates for PRK. This is most often due to the cornea being too thin for LASIK, though there can be other reasons. In PRK, the outermost corneal epithelial cells are removed. Then, a laser is used to reshape the cornea. A bandage contact lens is then placed to protect the cornea as it heals and the epithelial cells begin to grow back. PRK takes a little longer to heal, typically over 2-3 days. Here at the Kraff Eye Institute, we utilize iDesign 2.0 technology while performing both LASIK and PRK. This is the most advanced, highest-definition way of mapping and treating your cornea. This advanced technology allows us to treat patients who have astigmatism safely, including those with high levels of astigmatism.
If a patient is not to be a good candidate for LASER eye surgery, a doctor may recommend an implantable collamer lens procedure. In this type of procedure, the surgeon is implanting a synthetic lens, which is calculated for your specific vision needs, into the eye. The lens sits behind the colored part of the eye and your natural crystalline lens.
Although astigmatism can certainly be a nuisance, there is no reason to suffer from it. As you can see, there are plenty of options to correct astigmatism and achieve long lasting, clear vision. Interested in getting rid of your astigmatism for good? Call us to schedule your complimentary consultation today.