Description

Keratoconus (ker-uh-toe-KOH-nus) is an eye disease in which the clear, dome-shaped front part of the eye, called the cornea, becomes more and more thin, the more pronounced and bulges outward into a cone shape.

A cone-shaped cornea causes blurred vision and can cause sensitivity to light and glare. Keratoconus usually affects both eyes. However, it can affect one eye more than the other. It usually starts to affect people between the end of adolescence and the age of 30 years. The condition may progress slowly for 10 years or more.

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 worsens, you may need a cornea transplant.

A procedure called corneal collagen cross-linking may help to slow or stop the keratoconus progress, possibly avoiding the need for a future corneal transplant. This treatment can be offered in addition to the correction of vision with the above options.

Symptoms

The 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 the vision.

When to see a doctor

See your eye doctor if your vision is getting worse quickly. This could be caused by an irregular curvature of the eye, is called astigmatism. Your eye doctor may also look for signs of keratoconus during routine eye exams.

Causes

No one knows what causes keratoconus, although genetic and environmental factors are thought to be involved. Around 1 out of every 10 people with keratoconus also have a parent with the disease.

Risk factors

These factors can increase the risk of developing keratoconus:

  • Having a family history of keratoconus.
  • Rubbing the eyes with force.
  • Have certain conditions, such as retinitis pigmentosa, Down syndrome, Ehlers-Danlos syndrome, Marfan syndrome, hay fever, and asthma.

Complications

In some situations, the cornea can swell rapidly and cause a sudden decrease in vision and scarring of the cornea. This is caused by a condition in which the inner lining of the 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 may form a scar that affects vision.

Advanced keratoconus may also cause the cornea to become scars, in particular where the cone is the most prominent. One of scarring of the cornea causes the worsening of vision problems and may require a corneal transplant surgery.

Diagnosis

To diagnose keratoconus, an eye doctor will review your medical and family history and do an examination of the eyes. Other tests may also be done to find more information about the shape of the cornea.

Tests to diagnose keratoconus include:

  • Refraction of the eye. This test uses a special team of the measures of the eyes. It can involve looking through a device that contains wheels of different lenses, called a phoropter. This device helps to judge that the combination offers the most acute vision. Some ophthalmologists can use a hand-held instrument called a retinoscope to verify the eyes.
  • Slit-lamp examination. This test consists of directing a beam of light on the surface of the eye and the use of a low-powered microscope to see the eye. The doctor assesses the shape of the cornea and look for other possible problems in the eye.
  • The keratometry. This test consists in focusing a circle of light on the cornea and measures the reflection. This determines the basic shape of the cornea.
  • Computerized Corneal mapping. Special photo of the tests, such as the corneal tomography and topography of the cornea, the recording of images to create a detailed map of the cornea. Corneal tomography can also measure the thickness of the cornea. This type of test can often detect early signs of keratoconus before the disease is visible in the slit lamp examination.

Treatment

Treatment for keratoconus depends on the severity of the condition and of the rapidity with which the condition progresses. In general, there are two approaches to the treatment of keratoconus: slowing the progression of the disease and improve vision.

If keratoconus is the progress, the corneal collagen cross-linking may be recommended to reduce or prevent it from getting worse. This treatment aims to stabilize the structure of the cornea. Can reduce the swelling of the cornea and help you to get a better vision with glasses or contact lenses. This treatment also has the potential to prevent the need for a corneal transplant in the future.

The improvement of the vision depends on the severity of the keratoconus. Mild to moderate keratoconus can be treated with glasses or contact lenses. This is probably going to be a long-term treatment, especially if the cornea becomes stable over time or cross-linking.

In some people with keratoconus, the cornea becomes scarred with advanced disease. For others, the use of contact lenses is difficult. In these people, corneal transplant surgery may be necessary.

Lenses

  • Eyeglasses or soft contact lenses. Glasses or contact lenses can correct vision blurred or distorted at the beginning of keratoconus. But people often you need to change your prescription for eyeglasses or contact lenses, the shape of your corneas change.
  • Hard contact lenses. Contact lenses are often the next step in the treatment of more advanced keratoconus. Hard lenses include rigid gas permeable types. Hard lenses may feel uncomfortable at first, but many people get used to them and can provide an excellent view. This type of lens can be adapted to the corneas.
  • Piggyback lenses. If the rigid lenses are uncomfortable, an eye doctor may recommend "piggybacking" a hard contact lens in the top of a soft one.
  • Hybrid lenses. These contact lenses have a rigid center with a soft ring around the outside for added convenience. People who can't tolerate the hard contact lenses may prefer a hybrid lenses.
  • Scleral lenses. These objectives are useful for the very irregular shape changes in the cornea in advanced keratoconus. Instead of resting on the cornea as the traditional contact lenses do, scleral lenses sit on the white part of the eye, called the sclera, and the vault over the cornea, without touching it.

If you are using rigid or scleral contact lenses, make sure you have installed by an ophthalmologist with experience in the treatment of keratoconus. You will also need to have regular check-ups to determine if the lenses still fit well. A bad adjustment of the lens can damage the cornea.

Therapies

  • Corneal cross-linking. In this procedure, the cornea saturated with riboflavin eye drops and treated with ultraviolet light. This makes the cross-linking of the cornea, which stiffens the cornea to prevent more changes on the way. Corneal cross-linking can help reduce the risk of progressive vision loss by stabilizing the cornea early in the disease.

Surgery

Surgery may be needed if there is scarring in the cornea, the extreme thinning of the cornea, low vision, with the stronger of the prescription lenses or the inability to use, any type of contact lenses.

Depending on the location of the expansion cone and the severity of the condition, surgical options include:

  • Intrastromal corneal ring segments (ICRS). For mild to moderate cases of keratoconus, an eye doctor may recommend the insertion of small synthetic of the rings in the cornea. This treatment can help to flatten the cornea, which can help improve your vision and make contact lenses that fit better. Sometimes, this procedure is performed in combination with corneal cross-linking.
  • Cornea transplant. If there is scarring in the cornea, or of the extreme thinning, a corneal transplant may be necessary. Depending on the situation, an eye doctor may recommend replacement of all or part of the cornea with healthy donor tissue. A cornea transplant is known as a keratoplasty.

Corneal transplant for keratoconus in general, it is very successful. Possible complications include graft rejection, low vision, infection, and astigmatism. Astigmatism is often managed by using hard contact lenses, again, that it is generally more comfortable after a cornea transplant.

Preparing for your appointment

If you are having difficulty with your vision, it is likely to start by seeing an eye doctor called an ophthalmologist or an 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 to cross-linking or a cornea transplant.

Here's some information to help you prepare for your appointment.

What you can do

Before your appointment, make a list of:

  • The symptoms that you've had and for how long.
  • Recent major stress or life changes.
  • All medications, eye drops, vitamins, and supplements you are taking, including the dosage.
  • Questions to ask your eye doctor.

For keratoconus some basic questions to ask include:

  • What is the most likely cause of my symptoms?
  • What are other possible causes?
  • Do I need any tests?
  • Is this condition temporary?
  • What treatments are available, and which do you recommend?
  • What are the alternatives to the primary approach you're suggesting?
  • I have other health conditions. How can I best manage them together?
  • Do you have any brochures or other printed material that I can take with me? What sites do you recommend?

What to expect from your doctor

Your eye doctor is likely to ask you some questions, such as:

  • What types of symptoms have you had?
  • When did you begin experiencing symptoms?
  • The symptoms been continuous or occasional?
  • How severe are the symptoms?
  • Nothing seems to improve the symptoms?
  • Do you rub your eyes?
  • What, if anything, appears to worsen your symptoms?
  • Does anyone in your family have keratoconus?
Symptoms and treatment of Keratoconus