Keratoconus

Young men and women in the sunshine.

What is keratoconus?

The clear window at the front of your eye (the cornea) is usually an even round shape. Keratoconus is a degenerative eye disorder that causes the normal round cornea to steepen, protrude and become thin. As this progresses, the cornea forms an irregular cone-shaped bulge, causing blurred and distorted vision.

How common is keratoconus?

Keratoconus is relatively common, affecting up to 1 in 500 people.

What are the symptoms of keratoconus?

Early symptoms include blurred vision, worsening short-sightedness (myopia) and haloes and ghosting around light sources that can make night driving difficult. Further progressions results in significant visual impairment.

What causes keratoconus?

The underlying problem in keratoconus is a biomechanical weakness in the supporting collagen fibres of the cornea. This weakness allows the cornea to thin and bulge forward, distorting its normal shape and causing irregular astigmatism.

The exact cause of keratoconus is still uncertain although it is believed to be partly genetic and occurs more commonly in people with allergies like asthma, eczema and hayfever. There is also an association between eye rubbing and keratoconus.

How does keratoconus affect your vision?

A normal cornea allows light to enter the eye and provides focus so that a clear image can be seen. When the cornea loses its shape from keratoconus, your vision becomes blurred because the cornea cannot focus light properly. A distorted cornea causes light to focus at multiple points instead of a single point focus, resulting in an image that is blurred and out of focus.

Advanced keratoconus can also cause scarring of the cornea, which can severely decrease your vision by distorting focus and reducing the amount of light that can enter the eye.

A small number of patients may experience sudden, painful loss of vision if the fluid barrier on the back surface of the cornea is weakened and fluid from the inside the eye enters the thin cornea. This is called hydrops and often leaves a scar in the cornea after it resolves.

Does keratoconus affect both eyes?

Yes, but it may be asymmetrical and occasionally apparent in only one eye.

What is the natural history of keratoconus?

Keratoconus is often diagnosed in young people in their late teens or twenties. In 20% of people, the condition is progressive and gets worse with time. For most people, it stops progressing in their mid to late thirties due to natural age-related stiffening of the cornea.

What are the treatment options for keratoconus?

In the early stages or in mild forms of the disease, glasses or soft contact lenses may be sufficient to provide good vision. In more severe disease, rigid contact lenses are usually required to correct for the irregular astigmatism. In advanced keratoconus, where glasses or contact lenses are not able to provide adequate vision correction, intracorneal ring segments or a corneal transplantation may be required. If your keratoconus is progressing, a procedure called corneal collagen cross-linking is available to slow or stop the progression of the condition.

At your consultation with Dr Joanne Goh a detailed assessment will establish the procedure that is most likely to give you the best outcome.