When diagnosed with vision problems, including astigmatism, you may feel that eyeglasses are your only solution to fix your vision. Since the 1970s, contact lenses have also been an option for those diagnosed with astigmatism. Toric contact lenses are specifically designed for people with astigmatism issues arising from a different cornea curvature or lenses in your eyes, such as regular astigmatism, corneal astigmatism, or lenticular astigmatism. Are toric contact lenses suitable for you?
What Is Astigmatism?
Image via Flickr by n4i.es Licensed CC BY 2.0
You must have an eye examination in order to be diagnosed with astigmatism. Astigmatism is a condition that affects the curvature of your eye’s cornea or lens. In other terms, it’s a refractive error. In an eye with astigmatism, the cornea or lens is curved so that the refraction of your eye differs between the horizontal and vertical planes. This alteration of the curvature of the cornea or lens causes issues with seeing fine details and blurry vision.
Visualizing the normal eye as shaped like a basketball may help you understand how astigmatism affects vision. In a person with astigmatism, the eye is shaped more like an American football; that is to say, it’s more egg or oval-shaped than round. If astigmatism has its steepest curve running vertically, such as it would be if a football was lying on its side, the condition is referred to as with-the-rule astigmatism. If the steepest curve runs vertically, such as it would be if a football was sitting on its end, it is referred to as against-the-rule astigmatism.
This condition may also be referred to as regular astigmatism, corneal astigmatism, or lenticular astigmatism. Corneal astigmatism occurs when the front surface of your eye (cornea) has a different curvature in one direction. Lenticular astigmatism is a result of a difference in curvature in the lens.
The problem with astigmatism is that while the normal eye perceives light rays forming a single point, the eye with astigmatism sees light rays coming together as two separate focal points. The cornea or lens is curved so that the refraction of your eye differs between the vertical and horizontal planes. These issues cause blurry vision and trouble seeing fine details for someone with astigmatism.
Five different types of astigmatism can affect your vision, including these:
- Myopic astigmatism light creates two focal points, one in front of the retina and one on the retina itself.
- In simple hyperopic astigmatism, light creates two focal points, one on the retina itself and another focal point in the area that’s a virtual point behind the retina.
- Compound myopic astigmatism creates two light focal points in front of the retina but at two different locations in front of the retina.
- In Compound Hyperopic Astigmatism, light creates two focal points, both of which are located in a virtual area behind the retina but at two different virtual regions behind the retina.
- Mixed Astigmatism is where light rays create two focal points, one in front of the retina and the other behind the retina.
What Are Toric Contact Lenses?
Toric contact lenses are prescribed for people with astigmatism to help correct the condition. Toric lenses are different from standard contact lenses due to their shape, named after the shape, torus. A lens with several focal lengths is achieved by slicing off the edge of the torus shape. A design with multiple focal lengths is critical for someone with astigmatism.
Each set of toric lenses is different based on how an individual’s cornea deviates from the norm. Toric lenses are designed specifically to stay in proper orientation in the eye to ensure the best vision possible for someone with astigmatism, which is why proper fitting is critical.
What Types of Material Can Be Used to Make Toric Lenses?
Firstly, toric lenses are always soft contacts made from only two material types: hydrogel or silicone hydrogel. The difference is that silicone hydrogel lenses are more breathable than hydrogel lenses. For that reason, they may also be a bit more expensive. Due to the uniqueness of every eye with astigmatism, it can take some trial and error to get the right fit. Your eye doctor may have you try several brands before finding the most comfortable one that sharpens your vision with the highest accuracy.
Due to the complexity of finding the right lenses for your astigmatism, the contact fitting costs might be higher than those for standard contact lenses. Similarly, there may be a higher cost when it comes time to replace your lenses. It requires more time and more significant expertise from your eye doctor to fit you for toric lenses properly.
What Other Lenses Can Correct Astigmatism?
There are other options for contact lenses that correct astigmatism, but they have some drawbacks compared to toric lenses. One of them is gas-permeable contact lenses that can also be used in eyes affected by astigmatism. They may be referred to as GP lenses, rigid gas permeable lenses, or RGP lenses.
GP lenses correct astigmatism without a toric design because they’re rigid, and thus they stay the same shape, regardless of the misshapenness of an eye with astigmatism. Rather than conforming to the astigmatic eyes, such as non-toric soft contacts do, they remain rigid over the uneven surface of the eye. There are also GP lenses with toric designs for those with unusual or high levels of astigmatism. The drawback to GP lenses is their thickness and rigidity. Some people may find them uncomfortable and have a more challenging time adjusting to them.
Another option is scleral lenses, a type of GP lens larger in size. Scleral lenses also provide astigmatism correction, even on irregular eye surfaces. In all cases, fitting for toric lenses or any other contact lens options to correct astigmatism requires an eye exam, testing, and consultation with an eye doctor.
When you’re ready to discuss the option of toric lenses or wish to examine whether toric lenses are suitable for you, reach out to the experts at Northeastern Eye Institute. With 15 locations across northeastern Pennsylvania, you’re sure to find a doctor near you for your contact lens needs. You can reach us at 570-342-3145 or use our convenient Contact Us form on our homepage to send us a message.