Keratoconus is corneal damage that occurs in 1 per 1000 inhabitants, mostly in adolescents.

The cause of keratoconus is unclear and its progression speed is difficult to be defined (progression is observed in 20% and in 80% it tends to be stable). Kerotoconus is usually bilateral process (i.e. that both eyes are affected), and both vision when looking at far and close distances is impaired. Rapid progression of the disease may warrant a need for surgical therapy.

The cornea is a transparent anterior part of the eye that has a spherical shape. The cornea has several layers that are connected by collagen fibres. Keratoconus occurs when these collagen connections between corneal layers get weaker or disappear completely. This becomes evident as thinning of the cornea or elongation of the cornea. As a result the shape of the cornea changes to conical that causes vision impairment.

Usually the eye gets short-sighted and irregular astigmatism develops.