This is a condition where the centre of the cornea thins.

The pressure of the aqueous humour behind the cornea causes it to become conical in shape, and to bow forward much more than normal. This results in irregular astigmatism, which initially can be corrected with spectacles.

As it progresses, visual acuity is inadequate with spectacles, and rigid contact lenses are required. This restores stable visual acuity by replacing the irregular corneal surface with a smooth refractive surface.

Management progresses as the thinning worsens. Specialist keratoconic lenses are available. Some practitioners also use soft toric lenses in the early stages of the condition, although these need to be made thicker than they would normally.

To find out more about keratoconus, visit our dedicated page.