This is a condition that affects about 1 in 500 to 1 in 1000 of the population. In this disorder the cornea changes shape due to thinning to a conical form in its most extreme form. It usually starts in the early teens but can occur earlier and and also in the late 40s. The exact trigger for this condition is unknown but it has been found that the fibres that are embedded in the cornea loose their organisation and attachments to each other. This leads to weakening of the cornea, thinning and the change of shape. Most people have this condition in its mild form and manage well with glasses or contact lenses.
Recently, a new treatment, UV-X linking, has been shown to strenghten the cornea and slow down the progression of the disease in many patients.

Pellucid marginal degeneration and keratoglobus (a very rare condition) are very similar to keratoconus and probably are the same disease. Again, these conditions are suitable for UV-X linking.

UV-X linking

This new treatment has been pioneered by Prof Seiler (Zurich, Switzerland). The treatment is performed as a day case procedure under local anaesthesia. Riboflavin drops are instilled on the eye and the UV light is pulsed on the eye. The riboflavin makes a strong cross link with collagen fibres of the cornea. This strengthens the cornea to slow down /reduce further progression of the keratoconus. It is not cure but a means of stabilising the condition for a few years and the treatment can be repeated again. UV-X can be combined with Corneal implants (see below).

These are tiny plastic semicircular rings surgically implanted into the cornea to flatten the corneal surface and improve vision in patients with keratoconus. Inserts can improve contact lens wear in most patients. They are not suitable for all patients with keratoconus. Implantation does not affect the central optic zone, does not involve the removal of any tissue, and can be reversed if vision changes, thus preserving all future options for vision correction or adjustment.

Laser Treatment for Keratoconus

Though laser vision correction is contraindicated in keratoconus, the excimer laser can be used to flatten the peak of the cone or remove scarring that occurs in advanced cases. This can allow a better fit for contact lens on the corneal surface and 'put-off' corneal transplantation.

Corneal Transplantation

If all the above treatments fail then a corneal transplant is indicated. There are two types of corneal transplants in keratoconus. Deep lamellar keratoplasty (DLK) removes the diseased cornea but leaves behind the healthy posterior layer (endothelium). The diseased corneal layer is replaced by a healthy cornea from a donor eye. Full thickness or penetrating Keratoplasty is performed if there has been damage to the posterior layer (hydrops) and the whole cornea is replaced with a donor cornea. Both types of transplants are sutured into place (see picture). Corneal transplants for keratoconus is a very successful treatment with upto 96% survival at 5 years after surgery but the transplant may take 12-18 months to 'bed in'.