When your cornea bulges outward, it can cause blurry vision and make your eyes sensitive to light. Find out about symptoms, causes and treatment for this eye condition.
Keratoconus (ker-uh-toe-KOH-nus) is an eye condition in which your cornea — the clear, dome-shaped front of your eye — gets thinner 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. However, it can affect one eye more than the other. It generally begins to affect people between the late teens and 30 years of age. The condition may progress slowly for 10 years or longer.
In the early stages of keratoconus, you might be able to correct vision problems with glasses or soft contact lenses. Later, you may have to be fitted with rigid, gas permeable contact lenses or other types of lenses, such as scleral lenses. If your condition gets worse, you may need a cornea transplant.
A procedure called corneal collagen cross-linking may help to slow or stop keratoconus from progressing, possibly preventing the need for a future cornea transplant. This treatment may be offered in addition to the vision correction options above.
In keratoconus, your cornea thins and gradually bulges outward into a cone shape. This can cause blurry, distorted vision.
Symptoms of keratoconus may change as the disease progresses. They include:
See your eye doctor if your eyesight is worsening rapidly, which might be caused by an irregular curvature of the eye, called astigmatism. Your eye doctor also may look for signs of keratoconus during routine eye exams.
No one knows what causes keratoconus, although genetic and environmental factors are thought to be involved. Around 1 in 10 people with keratoconus also has a parent with the condition.
These factors can increase your chances of developing keratoconus:
In some situations, your cornea may swell quickly and cause sudden reduced vision and scarring of the cornea. This is caused by a condition in which the inside lining of your cornea, called Descemet's membrane, breaks down. This causes fluid to enter the cornea, a condition known as hydrops. The swelling usually goes down by itself, but a scar may form that affects your vision.
Advanced keratoconus also may cause your cornea to become scarred, particularly where the cone is most prominent. A scarred cornea causes worsening vision problems and may require cornea transplant surgery.
To diagnose keratoconus, your eye doctor will review your medical and family history and conduct an eye exam. Other tests also may be done to find out more about the shape of your cornea. Tests to diagnose keratoconus include:
Treatment for keratoconus depends on the severity of your condition and how quickly the condition is progressing. Generally, there are two approaches to treating keratoconus: slowing the progression of the disease and improving vision.
If keratoconus is progressing, corneal collagen cross-linking may be indicated to slow it or stop it from getting worse. This treatment aims to stabilize the structure of the cornea. It may decrease the bulging of the cornea and help achieve better vision with glasses or contact lenses. This treatment also has the potential to prevent you from needing a cornea transplant in the future.
Improving vision depends on the severity of keratoconus. Mild to moderate keratoconus can be treated with eyeglasses or contact lenses. This will likely be a long-term treatment, especially if the cornea becomes stable with time or from cross-linking.
In some people with keratoconus, the cornea becomes scarred with advanced disease. For others, wearing contact lenses becomes difficult. In these people, cornea transplant 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 to determine whether the lenses still fit well. An ill-fitting lens can damage your cornea.
You may need surgery if you have corneal scarring, extreme thinning of your cornea, poor vision with the strongest prescription lenses or an inability to wear any type of contact lenses. Depending on the location of the bulging cone and the severity of your condition, surgical options include:
Cornea transplant for keratoconus generally is very successful. Possible complications include graft rejection, poor vision, infection and astigmatism. Astigmatism is often managed by wearing hard contact lenses again, which is usually more comfortable after a cornea transplant.
If you're having difficulty with your vision, you'll likely start by seeing an eye doctor, called an ophthalmologist or optometrist. If your eye doctor determines that you might have keratoconus, you may be referred to an ophthalmologist who has had special training in corneal disease and surgery. A trained ophthalmologist can interpret corneal imaging studies and determine if you need cross-linking or a cornea transplant.
Here's some information to help you get ready for your appointment.
Before your appointment make a list of:
For keratoconus some basic questions to ask include:
Your eye doctor is likely to ask you a number of questions, such as: