Contact Lenses for Astigmatism:
Toric, GP and Hybrid Lenses
Too often, people mistakenly believe they canít wear contact lenses because they have astigmatism. The truth is, today there are plenty of excellent options for correcting astigmatism with contact lenses.
Here are the main types of contact lenses for astigmatism, in order of current popularity in the United States:
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Toric Contact Lenses
The term "toric contact lenses" usually is used to describe specially designed soft contact lenses that correct astigmatism. Most toric contacts for astigmatism are indeed soft lenses made either of a conventional hydrogel material or a highly breathable silicone hydrogel. But there are toric contact lenses made of rigid gas permeable (GP) contact lens materials, too.
Spherical lenses have the same power all around the lens, so it doesn't matter if the lens rotates on your eye. Toric lenses have two different powers in the lens, so they must remain in position for best visual acuity. Some toric lenses are heavier (ballasted) at the bottom to keep from rotating.
- Toric lenses have different powers in different meridians of the lens to correct the varying amount of nearsightedness or farsightedness in different meridians of the eye that characterizes astigmatism.
- Toric lenses have a design feature that enables the lens to rotate to the proper orientation on the cornea so the power meridians of the lens align with the appropriate meridians of the eye for clear vision.
Because every eye with astigmatism is unique, it can take more than one pair of soft toric contact lenses to find the brand and design that provides the best fit, comfort and visual acuity. Also, fitting toric contact lenses for astigmatism takes more expertise than fitting regular soft lenses. For these reasons, getting fitted with toric contact lenses typically costs more than a regular contact lens exam and fitting.
Also, because they have a more complex design, the cost of replacement toric contact lenses is higher than the cost of regular (spherical) soft contacts. The difference in cost will depend on the lens design, lens material, and the optical retailer you purchase them from. [Read more about contact lens costs and where to buy contact lenses.]
Gas Permeable Contact Lenses
Other popular contact lenses for astigmatism correction are rigid gas permeable contact lenses (also called RGP or GP contact lenses).
In most cases, GP contact lenses can correct astigmatism without a toric design. This is possible because gas permeable lenses are rigid and retain their spherical shape on the eye, instead of conforming to the irregular shape of the cornea of an eye with astigmatism like soft lenses do. The uniform front surface of the GP contact lens in effect replaces the misshapen cornea as the primary refracting (light-bending) surface of the eye, thereby correcting astigmatism without the need to control rotation of the lens with a toric design.
As mentioned earlier, there also are gas permeable contact lenses for astigmatism with toric designs. But toric GP contacts typically are only needed for relatively high amounts or unusual types of astigmatism.
Many people who choose to be fitted with gas permeable contact lenses for astigmatism find GP lenses provide noticeably sharper vision than toric soft contact lenses. But due to their rigid nature and thicker profile, gas permeable lenses can be more difficult to adapt to, and some people who try them simply cannot get accustomed to the sensation of GP lenses on their eyes.
Generally, fitting gas permeable contact lenses takes more time and expertise than fitting soft contact lenses (including toric soft lenses). And each RGP contact lens is custom-made to parameters specified by the prescribing eye care professional. For these reasons, getting fitted with gas permeable lenses typically costs more than getting fitted with soft lenses, and replacement costs of GP lenses are higher too.
Hybrid Contact Lenses
For some people who need contacts for astigmatism, hybrid contact lenses are the best choice. These lenses have a central zone made of a rigid gas permeable lens material, surrounded by a fitting zone made of a hydrogel or silicone hydrogel material.
When successfully fitted, hybrid contact lenses provide the best of both types of contact lenses for astigmatism the sharp vision of gas permeable lenses and wearing comfort thatís comparable to soft lenses.
And because hybrid contact lenses are about the same size as toric soft lenses (significantly larger in diameter than gas permeable contact lenses) and have thinner edges than GP lenses, there is less risk of these lenses dislodging from the eyes during sports and other activities.
Fitting hybrid contact lenses like fitting gas permeable contacts takes more time and expertise than fitting soft contact lenses. And, like GP contacts, these lenses are custom-made for each wearerís eyes. Hybrid contact lens fittings and lens replacements are comparable in cost with those of rigid gas permeable lenses (in other words, more expensive than soft lenses). But like GP lenses, hybrid contacts donít need to be replaced as frequently as soft contact lenses, making lens replacement costs more comparable to those of soft lenses over time.
Specialty Contacts for Astigmatism
There once was a time when choices among soft contact lenses for astigmatism were somewhat limited especially if you had special needs. But no more.
Today there are many brands and styles of toric soft lenses, including disposable contact lenses for astigmatism that are available in designs and materials for monthly, biweekly and even daily replacement.
There also are color contact lenses with toric designs that correct astigmatism while enhancing or changing your eye color, and toric bifocal contact lenses that correct both astigmatism and presbyopia. There even are toric silicone hydrogel lenses designed for up to 30 days of overnight wear.
For unusual or high amounts of astigmatism, special large-diameter gas permeable contacts called scleral lenses can be extremely effective. Also, several lens manufacturers offer custom contact lenses made of hydrogel and silicone hydrogel materials for these situations.
If you have astigmatism and are interested in wearing contact lenses, visit an eye doctor who specializes in fitting contact lenses for astigmatism. During a comprehensive eye exam and contact lens consultation, your doctor can advise you whether you are a good candidate for contact lens wear and which astigmatism-correcting contact lenses are best suited for your specific needs.
About the Author: Gary Heiting, OD, is senior editor of AllAboutVision.com. Dr. Heiting has more than 25 years of experience as an eye care provider, health educator and consultant to the eyewear industry. His special interests include contact lenses, nutrition and preventive vision care. Connect with Dr. Heiting via Google+.
[Page updated February 2015]
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