Those who live with astigmatism know that it can be a little hard for an optometrist to correct than other conditions like farsightedness or nearsightedness. The shape of your cornea has a lot of bearing on how well you can see, and a cornea with astigmatism doesn’t have an even surface.
That means regular, evenly corrected contact lenses don’t have the right shape to help a patient with astigmatism. But the eye care industry has some of the best minds in medicine working on ways around that irregularity.
Contacts Correcting Astigmatism
Getting glasses that will do the trick is one thing. Getting contact lenses that can compensate for astigmatism while providing the benefits of contact lenses is another. Regular contact lenses naturally shift around, and they have the same thickness (corrective power) all over. Fortunately, we’ve tested a few contact lens manufacturers’ solutions to corneal irregularities and focused on becoming experts at fitting them to every unique shape.
What Is Astigmatism?
Astigmatism is a refractive error, meaning that your eye has one or more problems with focusing images, caused by imperfect shape in either the cornea, the ocular lens, or the eye itself. The eye and the cornea both have to be perfectly spherical. But astigmatism usually owes to an imperfect shape in the cornea, with bumps or depressions interrupting the naturally smooth spherical surface.
How Astigmatism Affects Vision
Astigmatism makes the eye struggle with attaining focus. But unlike nearsightedness or farsightedness, the focal point isn’t as consistently aligned. It all depends on exactly where the irregular shapes of the cornea lie on its topography (the “map” of your cornea). But the effect for each patient with astigmatism is often the same:
- Blurry vision
- Needing to squint to see clearly
- Trouble seeing at night
To correct it, your contact lenses need to compensate somehow for the unique way your cornea happens to be out of shape.
What Causes Astigmatism?
Astigmatism is a refractive error. People sometimes get an astigmatism diagnosis, and they can receive a corrective prescription to manage their irregular cornea. Doctors can’t really agree on the cause. Some people are born with it, while some develop it in childhood or with adulthood. Still, others find they have astigmatism after they recover from eye surgery or heal from physical trauma to their eye.
Correction of astigmatism can be as easy as getting the right prescription with the proper corrective eyewear, like glasses or contacts.
But keratoconus is an eye disease, requiring comprehensive eye disease treatment or management when treatment can’t necessarily lead to recovery. The reason for that outcome is that keratoconus is always in development. The disease is characterized by corneal progressive (worsening with time) dystrophy (changing shape). And those worsening changes sometimes result in astigmatism. So keratoconus can sometimes directly embody a cause for astigmatism.
Specialty Contact Lenses
Whatever the cause of your astigmatism, there are specialty contact lenses that can get you seeing clearly again. There are a few options, each with advantages and downsides.
Scleral Contact Lenses
Scleral lenses are hard contact lenses that go all the way over your sclera (the whites of your eye) instead of covering only the cornea.
The scleral lens seals in your tears, forming a reservoir, and bathing your cornea. The moisture can provide nutrients and oxygen to damaged corneas, which can sometimes serve as a severe dry eye treatment. Scleral lenses can take some getting used to, however.
Rigid Gas Permeable Lenses
The rigidity of the lens smooths out the surface of your cornea because it maintains its own shape under the pressure of your eyelids—which allows visual quality to improve. Rigid gas permeable lenses can provide sharper vision for patients with astigmatism. The more severe astigmatism, the more recommendable RGP lenses become (up to a point). Some patients struggle with the feeling of their rigidity, however.
Ortho-K (Orthokeratology) Lenses
Ortho-K lenses are specialty RGP contact lenses that come in sets that gently work on your corneas while you sleep. They’re like braces for your eyes. Using them as directed affords you a temporary change in the shape of your cornea for correction of your refractive errors.
Ortho-K lenses are worn overnight and removed when you in the morning. Letting them work overnight gives you the chance to enjoy clear vision for the day, as your cornea holds a healthy shape. But Ortho-K requires the most rigorous contact lens hygiene since infection becomes a bigger risk without it.
Hybrid Contact Lenses
Hybrid lenses, sometimes called semi-rigid soft, permeable lenses, have a hard center and a soft outer ring. The rigid center corrects refractive errors to make your vision clearer. The soft outer ring holds the lens in place and provides comfort and wearability.
Hybrid lenses may work better for people who can’t wear regular lenses because their corneas are an unusual shape (irregular corneas). They can strike the “best of both worlds,” straddling the prosthetic benefits of RGP lenses and the comfort of soft lenses. But that comfort can elude some patients, depending on their unique astigmatism.
Toric Contact Lenses
Toric contact lenses are soft, comfortable contact lenses with different prescriptive powers, designed to swivel into place. These lenses only “sit” on your cornea in one way, so they come with a weighted anchor spot and markings to show you which edge faces up.
They get around your eye’s refractive error by correcting your vision at different strengths, in alignment with your astigmatism. Because they’re soft, though, they need to be perfectly fit at a contact lens fitting, and they can cost a little more for their intricate design. Moreover, it can take a while to find the perfect fit.
Every Astigmatism Deserves a Recommendation
For a more permanent solution to your astigmatism, you might consider laser eye surgeries. But you’d need a referral for surgery. While there’s probably a well-fitting contact lens out there, laser eye surgeries aren’t for everyone.
If the choices trying to decide which type of contact lens might be for you are overwhelming, there’s no need to worry. Each type has pros and cons, and your optometrist can tell you more.
Our optometrists have had their noses to the grindstone, perfecting our fitting procedures for corneal irregularities. We pride ourselves on making an optimal contact lens fit happen with every patient—regardless of whether it’s a routine fitting or one for a patient with specialty contact lens needs.