Normally, your cornea — the clear outer lens or "windshield" of your eye — has a dome shape, like a ball. Sometimes, the structure isn’t strong enough to hold its round shape and bulges outward, like a cone. This is called keratoconus.
Tiny fibers of protein in your eye called collagen help hold your cornea in place. When these fibers weaken, they can’t hold their shape, and your cornea becomes more and more cone-like.
It happens when you don’t have enough protective antioxidants in your cornea. Its cells produce harmful byproducts, the same way a car puts out the exhaust. Normally, antioxidants get rid of them and protect the collagen fibers. But if your antioxidant levels are low, the collagen weakens, and the cornea bulges.
Keratoconus Causes
We don’t know exactly what causes keratoconus. Researchers think that some people are more likely to get it from birth.
Keratoconus may be linked to several things, such as:
Family history. If someone in your family has this condition, you have a greater chance of getting it. If you have it, get your children’s eyes checked for signs starting around age 10.
Age. It usually starts when you’re a teenager. But it might show up earlier in childhood or not until you’re 30. It can also affect people aged 40 or older, but that’s less common.
Certain disorders. Studies have found a connection between keratoconus and systemic conditions such as Ehlers-Danlos syndrome, osteogenesis imperfecta, and retinitis pigmentosa.
Inflammation.Inflammation from things such as allergies, asthma, or atopic eye disease can break down the tissue of the cornea.
Eye rubbing. Rubbing your eyes hard over time can break down the cornea. It can also make keratoconus progress faster if you already have it.
Race. One study of more than 16,000 people with keratoconus found that people who are Black or Latino are roughly 50% more likely to get it than people who are white.
Keratoconus related to Down Syndrome
About 5%-30% of children with Down Syndrome have keratoconus. If you're born with Down Syndrome, your corneas are likely to be thinner and less rounded than those of people without Down Syndrome.
Can Keratoconus Cause Blindness?
Changes to the cornea can make it impossible for your eye to focus without glasses or contact lenses. You may need a corneal transplant to restore your sight if the condition gets bad enough.
Keratoconus and LASIK
Laser vision correction surgery, or LASIK, is dangerous if you have keratoconus. It can weaken your cornea more and make your vision worse. Even if you have only a small degree of keratoconus, don’t get LASIK surgery.
Keratoconus Symptoms
Keratoconus changes your vision in two ways:
As the front expands, your vision becomes more nearsighted. That means you can see objects clearly only when they’re up close. Anything too far away looks like a blur.
An eye doctor may spot the signs during an eye exam. You should also mention symptoms such as:
- Double vision when looking with just one eye
- Objects both near and far that look blurry
- Bright lights that appear to have halos around them
- Light streaks
- Triple ghost images
- Blurry vision that makes it hard to drive
As the cornea changes shape from a ball to a cone, the smooth surface becomes wavy. This is called irregular astigmatism.
Keratoconus vs. astigmatism
Regular astigmatism is a common eye problem that can be corrected with glasses or contact lenses. When you have regular astigmatism, the shape of your cornea is abnormal but in a consistent way. This causes light to bend as it enters your eye, distorting images. Doctors don't know what causes it. When you have keratoconus, the distortion in your cornea isn't uniform. Your vision can't be corrected completely with glasses or contacts.
Keratoconus Diagnosis
Your doctor needs to measure the shape of your cornea. There are different ways, but the most common is called corneal topography. The doctor snaps a photo of your cornea and checks it closely. Children of parents with keratoconus should have one every year starting at age 10.
Keratoconus Treatment
You’ll probably start with new glasses. If you have a mild case, new eyeglasses will help clear things up. If they don't, your doctor will suggest contact lenses. Rigid gas permeable contacts are usually the first choice. Over time, you may need other treatments to strengthen your cornea and improve your sight.
A treatment called cornea collagen crosslinking may stop the condition from worsening. Or your doctor could implant a ring called an Intacs under the cornea’s surface to flatten the cone shape and improve vision.
When other treatments don’t give you good vision, the last resort is a cornea transplant. This is a very safe operation, and it’s successful in more than 90% of cases. The doctor will remove the center of your cornea, replace it with one from a donor, and stitch the new one into place. You may need contact lenses afterward.
Keratoconus Self-Care
If you have keratoconus, it's important to avoid rubbing your eyes. This can cause further damage to the cornea. If your eyes itch, talk to your doctor about medication to help. You may have allergies that need treatment.
If you're a student, you may need to ask for accommodations to deal with your keratoconus. They could include:
- Asking for classroom handouts in a larger font, or handout versions of slide presentations
- Moving closer to the front of the classroom to see presentations more clearly
- Choosing a seat with good lighting, avoiding glare from windows
- Using a small reading lamp at your desk
- Requesting extra time in exams
- Using a handheld magnifying device
- Listening to audio versions of assigned reading material
- Increasing the font size and contrast on your computer screen
Keratoconus also can affect you at work, and you may need to ask your employer for accommodations. They could include:
- Being allowed to wear a hat or sunglasses indoors to reduce glare
- Seeking more control over the lighting at your workstation to reduce glare and flickering
- Asking to work from home so that you can control your environment more effectively
Takeaways
When you have keratoconus, your cornea develops a cone shape instead of the usual dome shape. It happens because fibers in your eye that normally help the cornea hold its shape weaken. You're at higher risk if you have a parent with keratoconus or certain conditions, including Down Syndrome. If your case is mild, glasses or contact lenses may be able to improve your vision.
Keratoconus FAQs
Can keratoconus be cured?
No, doctors don't have a way to reverse the symptoms and restore your cornea to its dome shape. However, several treatments can reduce the impact of keratoconus on your life. If your case is mild, glasses or contact lenses may be enough. For more severe cases, operations such as cornea transplant are available.
How fast can keratoconus progress?
No one can say exactly how fast your vision will change with keratoconus. Your condition will progress most quickly in the first 15 to 20 years after it begins. Most people find that their keratoconus levels off around age 40. For some people, their symptoms continue to worsen after age 50. Keratoconus tends to progress more rapidly if it starts at a younger age.
