What is keratoconus

Keratoconus (pronounced “keh-rah-toe-cone-us”) is a condition of the cornea. The cornea is the clear front surface of the eye.

In keratoconus, the cornea becomes progressively thin and irregular in shape. There is inherent weakness in the cornea, from a combination of genetic and environmental factors. In particular, eye rubbing can contribute to development and progression of keratoconus.

Keratoconus is diagnosed with a mapping scan of the cornea, which displays the shape and thickness of the cornea. Keratoconus can be asymmetric, with one eye worse than the other.

Who can get keratoconus?

Keratoconus is usually diagnosed in young people, in their late teens or early twenties. It affects up to 1 in 450 people. It is often associated with asthma, eczema, hayfever, or other allergic conditions of the eye.

How keratoconus affects your vision

As the cornea becomes more irregular in shape, it causes irregular astigmatism. This means you start to see less detail, and you may have blurred or distorted vision. There may also be an increased sensitivity to bright light and glare which could cause problems with night driving.

If the condition is mild, your high street optometrist at your local opticians will be able to help you with vision correction, either with glasses or soft contact lenses.

If you cannot achieve good vision in glasses, you may need specialised contact lenses to correct your vision. This can be provided by a hospital optometrist service. A small number of high street opticians also offer this service.

How keratoconus changes over time

Once you are diagnosed with keratoconus, you are monitored for progression. This is done with serial scanning every year, or more frequently if you are at high risk.

The risk of progression is higher when you are younger, and if you habitually rub your eyes. As you approach 35 or older, the risk of progression becomes much lower. Monitoring for progression is usually terminated as you get older, or if you have been followed up for a sufficiently long time.

If progression of keratoconus is detected, you will be offered a procedure called corneal cross-linking (CXL), to prevent keratoconus from getting worse.

Complications of advanced keratoconus

Some patients may develop scarring on the front of the eye. This may cause clouding of vision if it affects the central part of your vision.

A small number of patients may experience a sudden reduction in vision if fluid from the eye enters the thin cornea. This is called hydrops and will settle with time but could also cause scarring.

In very advanced keratoconus, you may require a corneal transplant to improve your vision. This is invasive surgery with a long recovery time for vision, and there is a risk of transplant rejection.

When to seek further advice?

If you no longer have an appointment scheduled and/or if you need to contact us urgently:

  • Monday to Friday, 9am-5pm: telephone the Royal Free Hospital on 020 7794 0500
  • Out of hours: attend the emergency department at the Royal Free hospital.