Keratoconus is a condition that results from an irregularly shaped cornea, which prevents light from focusing correctly on the retina. A cone-shaped cornea causes blurred vision and may cause sensitivity to light and glare. Keratoconus usually affects both eyes and generally begins to first affect people ages 10 to 25. The condition may progress slowly for 10 years or longer.
In the early stages of keratoconus, you can 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. If your condition progresses to an advanced stage, you may need a cornea transplant.
Signs and symptoms of keratoconus may change as the disease progresses. They include:
- Blurred or distorted vision
- Increased sensitivity to bright light and glare, which can cause problems with night driving
- A need for frequent changes in eyeglass prescriptions
- Sudden worsening or clouding of vision
These factors can increase your chances of developing keratoconus:
- Having a family history of keratoconus
- Rubbing your eyes vigorously
- Having certain conditions, such as retinitis pigmentosa, Down syndrome, Ehlers-Danlos syndrome, hay fever and asthma
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 breaks down, allowing fluid to enter the cornea (hydrops).
To diagnose keratoconus, your eye doctor (ophthalmologist) will review your medical and family history and conduct an eye exam. He or she may conduct other tests to determine more details regarding the shape of your cornea. Tests to diagnose keratoconus include:
- Eye refraction.
- Slit-lamp examination. In this test your doctor directs a vertical beam of light on the surface of your eye and uses a low-powered microscope to view your eye. He or she evaluates the shape of your cornea and looks for other potential problems in your eye.The doctor may repeat the test after you’ve had eyedrops applied to dilate your pupils. This helps with viewing the back of your eye.
- Keratometry. In this test your eye doctor focuses a circle of light on your cornea and measures the reflection to determine the basic shape of your cornea.
- Computerized corneal mapping. Special photographic tests, such as optical coherence tomography and corneal topography, record images of your cornea to create a detailed shape map of your cornea’s surface. The tests can also measure the thickness of your cornea.
Treatment for keratoconus depends on the severity of your condition and how quickly the condition is progressing.
Mild to moderate keratoconus can be treated with eyeglasses or contact lenses. For most people, the cornea will become stable after a few years. If you have this type, you likely won’t experience severe vision problems or require further treatment.
In some people with keratoconus, the cornea becomes scarred or wearing contact lenses becomes difficult. In these cases, surgery might be necessary.
- Eyeglasses or soft contact lenses.
- Hard contact lenses.
- Piggyback lenses.
- Hybrid lenses.
- Scleral lenses.
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 fitting remains satisfactory. 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. Several surgeries are available, depending on the location of the bulging cone and the severity of your condition.
Surgical options include:
- Corneal inserts.
- Cornea transplant.
Cornea transplant for keratoconus generally is very successful, but possible complications include graft rejection, poor vision, astigmatism, inability to wear contact lenses and infection.