By Hadley Gavin
Astigmatism is a common refractive error in the eyes that can lead to blurred or distorted vision. It occurs when the cornea, the clear front surface of the eye, or the lens inside the eye is irregularly shaped. Instead of being spherical, the cornea or lens may have an oval or football-like shape. This irregularity prevents light from entering the eye and being focused properly on the retina, which leads to distorted or blurred vision at all distances.
While astigmatism is a frequent eye condition, it’s often misunderstood or overlooked. People who experience astigmatism might not be aware of it, as the symptoms can develop gradually and often worsen over time. Fortunately, astigmatism can be managed and corrected with the right eye lenses. In this article, we will explore what astigmatism is, its causes and symptoms, and the various types of lenses available to correct it, helping you to find the best solution for your vision needs.
What Is Astigmatism?
Astigmatism is a refractive error, much like nearsightedness (myopia) and farsightedness (hyperopia). Refractive errors occur when the eye’s shape prevents light from focusing directly on the retina, which affects how well you can see. In the case of astigmatism, the curvature of the cornea or lens is not uniform. Instead of being shaped like a basketball, it is shaped more like a football, with two different curvatures. This causes light to focus on multiple points of the retina rather than just one, leading to distorted or blurred vision.
Astigmatism can vary in severity, ranging from mild to more pronounced cases. In mild cases, people might not even notice the condition, while more severe cases can result in significant vision problems that impact daily life.
Causes of Astigmatism
Astigmatism is typically present at birth and can be inherited, meaning it runs in families. It can also develop later in life due to certain eye injuries or surgeries, or as a result of a condition known as keratoconus, where the cornea becomes progressively thinner and more irregular in shape. In some rare cases, astigmatism can occur after an eye injury or surgery.
While the exact cause of the condition may not always be clear, regular eye exams are important for detecting astigmatism early, especially since the symptoms can be subtle.
Symptoms of Astigmatism
Astigmatism can cause a variety of visual symptoms, including:
- Blurred or distorted vision at all distances
- Frequent eye strain or fatigue, particularly when focusing on tasks like reading or using a computer
- Headaches, especially after prolonged periods of visual concentration
- Double vision or halos around lights
- Squinting to improve focus
If you experience any of these symptoms, it is important to schedule an eye exam with an optometrist. Early detection and proper correction can help manage the symptoms and improve your quality of life.
Corrective Lenses for Astigmatism
The good news is that astigmatism can be corrected effectively with the right type of lenses. The main goal of corrective lenses for astigmatism is to compensate for the irregular shape of the cornea or lens, allowing light to focus correctly on the retina. Below are the primary types of lenses used to treat astigmatism:
1. Toric Contact Lenses
Toric contact lenses are specially designed for people with astigmatism. Unlike standard spherical lenses, which have a uniform curvature, toric lenses have different powers in different meridians to address the uneven shape of the cornea. These lenses correct the refractive error by compensating for the irregularities in the eye’s shape, helping to focus light properly on the retina.
Toric lenses come in both soft and rigid gas-permeable (RGP) versions. Soft toric lenses are generally more comfortable and are suitable for most people with mild to moderate astigmatism. Rigid gas-permeable lenses, on the other hand, offer sharper vision and can be more effective for individuals with more severe astigmatism. They are also less prone to drying out or shifting position in the eye.
2. Glasses with Cylindrical Lenses
For those who prefer glasses over contacts, cylindrical lenses are the standard solution for astigmatism. These lenses are specially shaped to compensate for the uneven curvature of the cornea. Cylindrical lenses are available in different strengths, depending on the degree of astigmatism. The strength is indicated in “diopters” and helps to correct the blurring caused by the condition.
The key feature of cylindrical lenses is that they have different powers in different axes of the lens to focus light properly on the retina. These lenses are often prescribed in combination with spherical lenses to address any nearsightedness or farsightedness present along with astigmatism.
3. Hybrid Lenses
Hybrid contact lenses combine the best features of both soft and rigid lenses. The center of the lens is made from a rigid gas-permeable material, which provides the sharp vision needed to correct astigmatism, while the outer portion is made from a soft material for comfort. Hybrid lenses are an excellent option for individuals who require the sharpness of rigid lenses but prefer the comfort of soft lenses.
These lenses are especially helpful for those with irregular corneal shapes, such as in cases of keratoconus, where standard soft lenses may not provide adequate vision correction. Hybrid lenses provide stable, clear vision while maintaining comfort, making them a popular choice for those with more advanced astigmatism.
4. Scleral Lenses
Scleral lenses are large-diameter gas-permeable lenses that rest on the sclera (the white part of the eye) rather than directly on the cornea. They create a cushioning effect by trapping a layer of tears between the lens and the cornea, which can help to correct irregularities in corneal shape, such as those seen in severe astigmatism or keratoconus. Scleral lenses provide excellent vision correction and comfort but require more maintenance and a higher level of expertise to fit.
5. Refractive Surgery (LASIK)
For individuals with more severe or persistent astigmatism, refractive surgery, such as LASIK (Laser-Assisted in Situ Keratomileusis), may be an option. LASIK surgery reshapes the cornea using a laser to improve the way light enters the eye, allowing for more accurate focusing on the retina. While LASIK is not suitable for everyone, it can offer a permanent solution to astigmatism for those who are candidates.
Choosing the Right Solution for Astigmatism
The most suitable correction for astigmatism depends on various factors, including the severity of the condition, lifestyle, and personal preferences. Some individuals may prefer contact lenses for convenience, while others may opt for glasses due to ease of use or comfort. It is important to consult with an eye care professional to determine the best course of action based on individual needs and eye health.
Regular eye exams are crucial for monitoring the progression of astigmatism and ensuring that the correction remains effective. As astigmatism can worsen over time, periodic adjustments to lenses or prescription strength may be necessary to maintain optimal vision.
Conclusion
Astigmatism is a common yet treatable eye condition that affects millions of people worldwide. By understanding the causes, symptoms, and available corrective options, individuals with astigmatism can make informed decisions about the best approach to managing their vision. Whether through toric lenses, glasses with cylindrical lenses, hybrid lenses, or even refractive surgery, there are multiple ways to correct astigmatism and enjoy clear, comfortable vision. Regular eye exams and consultations with eye care professionals are key to maintaining eye health and achieving the best possible vision correction.
