The cornea is the clear, central part of the front of the eye. Normally the cornea has a round shape, like a ball but sometimes this structure isn’t strong enough to hold it’s round shape and the normal pressure exerted from inside the eye causes the cornea to bulge outwards. When this happens the condition is known as keratoconus. Although keratoconus can’t make you lose your sight, the changes it makes to the cornea can make it hard for the eye to focus without aid from glasses or contact lenses. Keratoconus can be especially dangerous if laser vision correction surgery is performed on the eye and as such anyone who is suffering from even the mildest keratoconus, should consult an optician before undergoing corrective surgery.

How is Keratoconus Diagnosed?

Your doctor may notice changes during an eye examination or you may mention symptoms which could be caused by keratoconus including;

  • Double vision when looking with just one eye
  • Objects both near and far look distorted but not blurred
  • Bright lights seem like they have halos around them
  • A sudden change of vision in just one eye

Although these symptoms might not be related to keratoconus your doctor must measure the curvature of your cornea to be sure. To help accomplish this there are several different kinds of instruments available. A keratometer shines a light pattern onto your cornea and by measuring the shape of the reflection your doctor can tell how your eye is curved. There’s also several computerised instruments available which are able to make three-dimensional maps of your cornea, in a process known as corneal topography.


In the vast majority of cases the cause of keratoconus is not known. Some research has indicated that have shown that keratoconus is hereditary, in that it runs in families and others have shown that people with certain medical conditions are at a higher risk of developing the condition. However most of the time there’s no disease or eye injuries which can account for why the eye has begun to change. Keratoconus typically begins in the teenage years, but it may also begin in childhood or anywhere up to the age of 30. The changes which occur in the shape of the cornea occur very slowly, over a number of years. And those with keratoconus often notice that their vision becomes slowly distorted. These changes can stop at any time or may continue on for several years and in the majority of cases, both eyes are effected.


Treatment for keratoconus usually begins with a new prescription for glasses or in some cases contact lenses may be recommended. In most cases these will help sufficiently to correct the problems with vision caused by keratoconus. However there are some cases of keratoconus where the symptoms will keep getting worse and eventually, contact lenses won’t be able to provide clear vision. Keratoconus can change your vision in two main ways and treatment will mainly depend upon which way you are affected by it. Firstly as the cornea changes from its natural ball shape into a more cone like form, the smooth surface becomes slightly distorted and this is known as irregular astigmatism. In other cases as the front of the cornea expands the eye can become more nearsighted and anything far away will appear blurry. Whilst new glasses are usually enough in mild cases it may become necessary to use contact lenses with. Rigid lenses are favoured for patients with keratoconus as soft lenses won’t be able to flatten out the cornea to fit well. In the most severe cases the lenses may not give clear vision or the side effects of using rigid lenses may make the cornea cloudy. When this occurs a corneal transplantation may be recommended.