Keratoconus
Keratoconus is a condition which occurs when your cornea, the clear, dome-shaped front surface of your eyes; thins gradually and starts bulging outward into a cone shape. The tiny fibers of protein in your eye which is known as collagen help in holding your cornea in place. When these fibers are weakened, they are unable to hold their shape. The cornea, therefore, gets more and more cone-like. The condition is caused when you don’t have enough protective antioxidants in the cornea.
In the early stages of this condition, you can use glasses or soft contact lenses. But if your condition becomes advanced, you might need a cornea transplant.
Symptoms
Signs and symptoms of this condition can change as the condition progresses. They include the following:
- Blurred or distorted vision
- Increased sensitivity to bright light and glare, and this can lead to problems with driving at night
- Needing to change eyeglass prescriptions frequently
- Sudden worsening or clouding of vision
See your eye doctor or ophthalmologist, if you feel your eyesight is worsening rapidly. Your doctor will conduct a routine eye exam, and he/she will look for signs of keratoconus.
Causes & risk factors
What exactly causes this condition is unknown, though genetic and environmental factors are generally considered to be involved. Around 1 in 10 people also have a parent with this condition.
These factors can also increase your chances of developing this condition:
- Rubbing your eyes vigorously
- Having a family history of keratoconus
- Having certain conditions, which can include Down syndrome, retinitis pigmentosa, Ehlers-Danlos syndrome, hay fever and asthma
Diagnosis
For the diagnosis of keratoconus, your ophthalmologist will review your medical and family history after which he/she will conduct an eye exam. He/she might conduct other tests to determine more details regarding the shape of your cornea. Tests to diagnose keratoconus include:
Eye refraction
In this method, your eye doctor makes the use of special equipment that measures your eyes and checks for any vision problems. He/ she may ask you to look through a device containing wheels of different lenses to help judge which combination is able to give you the sharpest vision. Some doctors might also use a hand-held instrument in order to evaluate your eyes.
Keratometry
This test involves your doctor focusing a circle of light on the cornea and measuring the reflection in order to determine the basic shape of your cornea.
Slit-lamp examination
This test involves your doctor directing a vertical beam of light on the surface of your eye. Next, she will use a low-powered microscope to view your eye. He/she will evaluate the shape of your cornea and looks for other potential problems in your eye.
Computerized corneal mapping
Special photographic tests, including corneal tomography and corneal topography, can be used to record images to create a detailed shape map of your cornea. Corneal tomography can also be used to measure the thickness of your cornea. Corneal tomography can often detect early signs of keratoconus before this disease is visible by slit-lamp examination.
Treatment
In most cases, you will probably receive new glasses, especially if your case is mild. If mild eyeglasses don’t clear things up for you, your doctor might suggest contact lenses. Over time, other treatments will also be required to strengthen your cornea and improve your eyesight.
A treatment which is known as cornea collagen crosslinking might stop the condition from getting worse. Your doctor might also implant a ring known as an Intact under the cornea’s surface. This can help to flatten the shape of the cone and improve the vision.
Surgery
Surgery might be required if you are having corneal scarring, extreme thinning of the cornea, poor vision with very strong prescription lenses, or inability to wear contact lenses. Surgical options include the following:
Penetrating keratoplasty
If you are having corneal scarring or extreme thinning, you will likely require a cornea transplant or a keratoplasty. In this procedure, doctors are going to remove a full-thickness portion of your central cornea. This is then going to be replaced with donor tissue.
Deep anterior lamellar keratoplasty (DALK)
This procedure helps to preserve the inside lining of the cornea or the endothelium. This can help one in avoiding the rejection of this critical inside lining that may occur if a full-thickness transplant is performed.