What is it?

We see through the cornea, which is the clear outer lens or “windshield” of the eye. Normally, the cornea has a dome shape, like a ball. Sometimes, however, the structure of the cornea is too weak to hold this round shape and the cornea bulges outward like a cone. This condition is called keratoconus.

Tiny fibres of protein in the eye called collagen help hold the cornea in place and keep it from bulging. When these fibres become weak, they cannot hold the shape and the cornea becomes progressively more cone-shaped.

Keratoconus is caused by allergies. Chronic eye rubbing will result in the weakening of the cornea, causing the condition to progress.

How is it treated?

Treatment usually starts with new eyeglasses. If eyeglasses do not provide adequate vision, then contact lenses, usually, rigid gas permeable contact lenses may be recommended. With mild cases, new eyeglasses can usually restore clear vision. Eventually, though, it will probably be necessary to use contact lenses or seek other treatments to strengthen the cornea and improve vision.

A treatment called cornea collagen cross-linking is often effective to help prevent worsening of the condition.

Intacs are implants that are placed under the surface of the cornea to reduce the cone shape and improve vision.

A specialised laser procedure called PTK can smooth out a raised scar (like a callus) and improve contact lens comfort.

If eyeglasses and contact lenses no longer provide stable and comfortable good quality vision, a cornea transplant can be performed. This involves removing the centre of the cornea and replacing it with a donor cornea that is stitched into place.