Keratoconus

Keratoconus (literally, conical cornea) is a thinning of the central zone of the cornea, the front surface of the eye. The normal pressure within the eye makes the thinner area of the cornea bulge forward slightly.

keratoconus
The Causes of Keratoconus

Keratoconus is an inherited disorder that occurs in about one in 3 000 people. It is a recessive condition requiring genetic factors to be inherited from both parents, so the chances of the children of a person with keratoconus also having the condition are low (around one in 50).

Keratoconus usually becomes apparent between the ages of 10 and 25 years. It is sometimes associated with other conditions such as allergies, infantile eczema, asthma, reduced night vision, double jointedness and, in rare instances, with occasional short bouts of chest pain.

Because keratoconus is a genetic condition, it cannot be treated with drugs but glasses and contact lenses can give good vision and surgery can be used to treat severe cases. Keratoconus does not cause blindness.

Interestingly, about 60% of people with keratoconus go on to tertiary education, compared with 15 per cent of the population as a whole.

The Symptoms

The initial symptom of keratoconus is blurred vision, which is caused by short sightedness and astigmatism. These occur because of the changing shape of the cornea as it bulges forward and often they are indistinguishable from short sightedness and astigmatism caused by other factors. At this stage, good vision generally can be obtained with spectacles.

The Best Ways to Manage it

As keratoconus progresses, the shape of the cornea becomes irregular and it is not possible to correct the vision with spectacles alone. In such cases, rigid contact lenses can be used to provide good vision. The contact lenses essentially provide a new, regular front surface for the eye, eliminating the distortions caused by the keratoconus.

A rigid gas permeable (RGP) contact lens is used to correct the irregular corneal shape. Some people will get excellent vision compared to glasses in the later stages of the disease. Our practices have the latest equipment to manage keratoconic contact lens fittings and our highly trained optometrists will be able to fit RGP contact lenses. These are some of the lenses we stock:

Because the cornea continues to change shape, it is important that people with keratoconus have regular examinations to ensure that their contact lenses fit correctly. A poorly-fitting contact lens can cause abrasions and scarring.

In about 85% of cases of keratoconus, the condition gradually stabilises by the age of 35 years. In the remaining 15%, the condition progresses and vision and tolerance to contact lenses may deteriorate. For these people, a corneal graft may be necessary.

A corneal graft or keratoplasty is an operation in which the thinned area of the cornea is removed and replaced by normal tissue transplanted from a donor cornea. Corneal grafting is used only when all other methods for correcting vision have failed to provide good vision. The success rate for corneal grafts is extremely high although most people will still need to wear glasses or contact lenses.

Corneal Topography

We have the latest equipment to diagnose and treat Keratoconus. Computerised corneal topography is a three-dimensional imaging process used to map the surface power of the cornea. The data points gathered are then digitised and analysed by sophisticated computer software. The result is a detailed map of the corneal curvature much like a topographical map of land.

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