Keratoconus

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What Is Keratoconus?

Keratoconus is an uncommon condition in which the cornea (clear front window of the eye) becomes thin and protrudes. Keratoconus literally means a cone shaped cornea. This abnormal shape can cause serious distortion of vision.

What Causes Keratoconus?

Despite continuing research, the exact cause of keratoconus remains unknown. Research indicates that keratoconus may be caused by an excess of enzymes that break down the proteins within the cornea, causing the cornea to become thin and stretched.

The genetic inheritance of keratoconus has not clearly been determined. It appears that it may involve a number of different genes. Blood relatives of someone affected with keratoconus have minor changes in their corneas that may indicate that keratoconus probably varies both in the specific genetic cause, as well as in its expression within a family.

Vigorous eye rubbing can contribute to the disease process. People with keratoconus should absolutely avoid rubbing their eyes. This is sometimes very difficult because some allergies, which cause itchy, irritated eyes, are more commonly associated in patients with keratoconus. Drops such as Patanol can help.

What Are The Symptoms Of Keratoconus?

Blurring and distortion of vision are the earliest symptoms of keratoconus. Symptoms usually appear in the late teens or early twenties. The disease will often progress slowly for 10 to 20 years, then stabilise.

In the early stages, vision may be only slightly affected, causing glare, light sensitivity and irritation. Each eye may be affected differently. As the disease progresses and the cornea steepens and scars, vision may become distorted.

Spectacles or a rigid contact lens (above) can often give clear vision.

A sudden decrease in vision can occur if the cornea swells. The cornea swells when the elastic inner layer of the cornea develops a tiny crack, created by the strain of the cornea’s protruded cone-like shape. The swelling may persist for weeks or months as the crack heals and is gradually replaced by scar tissue.

How Is Keratoconus Treated?

Mild cases are successfully treated with glasses or specially designed contact lenses. When vision is no longer satisfactory with glasses or contact lenses, surgery, usually a corneal transplant, is recommended.

If a corneal transplant is necessary for advanced keratoconus, vision usually improves. Glasses or contact lenses are often necessary after the surgery. As in any eye surgery, complications such as transplant rejection, infection and loss of vision can occur, so results cannot be guaranteed.

Recently a new minor surgical treatment to slow or stop the progression of the disease in younger people has become available. This is called corneal collagen crosslinking (C3R). In corneal crosslinking, riboflavin drops are applied to the patient’s corneal surface. Once the riboflavin has penetrated through the cornea, Ultraviolet A light therapy is applied. This induces collagen crosslinking, which has been shown in several studies to stabilise keratoconus. In a few cases, flattening of the cornea with improved visual acuities have actually occurred. It is still under investigation at this stage but is promising. Dr Sullivan is involved in the Melbourne trial being run through the Royal Victorian Eye and Ear Hospital. Some doctors are recommending that patients take riboflavin tablets 20mg per day, even if they are not undergoing the crosslinking treatment, and this seems reasonable and safe although it is unproven.

Like To Know More?

Keratoconus Australia has a web site at http://www.keratoconus.asn.au/ and has regular information sessions. Their email address is info@keratoconus.asn.au, and the contact phone number is 0409644811.

Check out the (American) National Keratoconus Foundation website at: http://www.nkcf.org/, or the centre for keratoconus, at: http://www.kcenter.org/

The Melbourne Lions Corneal Donation Service also has useful information, and is found at http://cera.unimelb.edu.au/new/eyebank/recipient.html

The Global Keratoconus Foundation www.kcglobal.org