What is Keratoconus?

Keratoconus is a degenerative, non-inflammatory condition characterised by thinning and weakening of the central cornea. Due to the internal pressure of the eye, the cornea then bulges forward, giving rise to a conical shape – from which the condition gets its name. It is essentially a progressive condition, though the duration and amount of progression varies between individuals. Quite often it starts in the teens and progresses for around ten years before stabilising and can affect just one or both eyes.

Similar/related conditions

Posterior Keratoconus – a rare disorder, usually congenital, with non-progressive thinning of the inner cornea while the front surface remains normal.

Pellucid Marginal Degeneration - thinning at the edge of the cornea while the central cornea remains normal thickness. Causes significant irregular astigmatism.

Keratoglobus - generalised thinning of the whole cornea.

Visual consequences

Spectacle lenses are designed assuming the front of the eye is a smooth regular shape. When distortions form as a consequence of keratoconus, then spectacles do not work that well. Visual symptoms include ghosting, flare and haloes round lights, multiple images and general blurriness. Due to the corneal thinning, the spectacle prescription is often not very stable either, requiring frequent updating of glasses.

Contact lenses

Vision is often dramatically improved by the use of contact lenses which provide a new regular front surface for the cornea. Most people with keratoconus can see normally once they start wearing contact lenses, as they reduce the frustrating visual symptoms listed above.