Keratoconus is a condition of the eye where the normally-rounded surface of the cornea thins and bulges outwards, causing a 'cone'-like effect. The word 'keratoconus' comes from the Greek roots for 'cornea' and 'cone'.
The condition is relatively rare - although many cases are not diagnosed because they are not very severe, the incidence of this condition is estimated to be 1 in 2000 people
It is not known what actually causes keratoconus, although some genetic links have been found (around 10 - 15% of keratoconus patients have a close relative with keratoconus)
Keratoconus usually affects both eyes, although the signs will generally appear in one eye as much as five years before the other
Age of onset is usually late teens/early adult
The rate of progression of keratoconus varies - on average, a patient will be able to correct their vision with glasses or contact lenses for ten years before operations are necessary
Treatment of Keratoconus
The most obvious symptom of keratoconus is blurred vision - in early stages this is relatively mild and can be managed with glasses. Later on, gas-permeable (hard) contact lenses are required. Distortion (such as double vision and other effects) will generally occur, especially in later stages.
However, the shape of the cone can eventually become so steep that contact lenses can no longer be worn comfortably, if at all. Additionally, scarring can occur on the surface of the cornea making vision extremely poor. If either happens, there is one treatment left - replacement of the cornea itself.
There are two main methods of corneal transplant - conventional keratoplasty (replacement of the entire cornea) and deep lamellar keratoplasty (where just the centre section of the cornea is replaced).
Both operations have approximately a 95% success rate. In cases of failure, a second operation is frequently successful. Rejection is relatively rare as the cornea has no blood flow.
In recent years, such surgery, although complicated, can be carried out as a day-case operation with the patient returning home the same day as surgery. However, many hospitals prefer their patients to stay at hospital overnight for observation.
Vision after the operation is rarely perfect, and often poor. However, for most patients, vision can be corrected successfully with glasses or contact lenses. It will usually take several months before the eye stabilises enough so that glasses and contact lenses can be prescribed.