Keratoconus (ker-uh-toe-KOH-nus) occurs when your cornea — the clear, dome-shaped front surface of your eye — thins and gradually bulges outward into a cone shape. A cone-shaped cornea causes blurred vision and may cause sensitivity to light and glare. Keratoconus usually affects both eyes and typically begins during puberty or in your late teens. The condition may progress slowly for 10 years or longer.
In the early stages of keratoconus, vision problems can be corrected with glasses or soft contact lenses. As keratoconus progresses, you may have to be fitted with special rigid gas permeable contact lenses. Advanced keratoconus may require surgery.
Signs and symptoms of keratoconus may change as the disease progresses. They include:
When to see a doctor
If you're considering laser-assisted in-situ keratomileusis (LASIK) eye surgery, make sure your doctor checks for signs of keratoconus before you proceed.
What triggers corneal thinning in keratoconus usually is unknown. Some experts believe that keratoconus may not be a single disorder but instead could stem from several different causes. If you have a habit of vigorously rubbing your eyes, it's possible to injure your corneas. A few people who frequently and vigorously rub their eyes develop keratoconus, though a cause-and-effect relationship remains unproved.
These factors can increase your chances of developing keratoconus:
In advanced keratoconus, your cornea may become scarred, particularly where the cone forms. A scarred cornea causes worsening vision problems and may require corneal transplant surgery. The effect of ongoing vision problems on your daily life can also lead to anxiety.
Preparing for your appointment
If you're having difficulty with your vision, you'll likely to start by seeing an ophthalmologist or optometrist. If it's determined that a corneal transplant may be needed, you may be referred to an ophthalmologist who specializes in eye surgery.
Because appointments can be brief and there's often a lot of ground to cover, it's a good idea to be prepared. Here's some information to help you get ready, and what to expect from your eye doctor.
What you can do
Your time with your doctor is limited, so preparing a list of questions will help you make the most of your time together. List your questions from most important to least important in case time runs out. For keratoconus, some basic questions to ask your doctor include:
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment.
What to expect from your doctor
Tests and diagnosis
Your ophthalmologist can diagnose keratoconus during a routine eye exam, but more sophisticated tests may be done to determine the exact shape of your cornea. Tests to diagnose keratoconus include:
Treatments and drugs
Treatment for keratoconus depends on how severe it is and how fast it's progressing. Mild to moderate keratoconus can be treated with eyeglasses or contact lenses. For most people, the cornea will stabilize after a few years, without causing severe vision problems. In about 10 to 20 percent of people with keratoconus, however, the cornea becomes scarred or they're unable to continue wearing contact lenses. In these cases, surgery might be necessary.
If you're using rigid or scleral contact lenses, make sure to have them fitted by an eye doctor with experience in treating keratoconus. You'll also need to have regular checkups and refittings. A poor-fitting hard contact lens can further damage your corneas if you have keratoconus.
Most cases of keratoconus aren't preventable, but you can take some steps to be sure you don't cause it yourself:
Last Updated: 2010-10-28
© 1998-2014 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "MayoClinic.com," "Mayo Clinic Health Information," "Reliable information for a healthier life" and the triple-shield Mayo logo are trademarks of Mayo Foundation for Medical Education and Research.
Terms and conditions of use