Keratoconus is a visual condition named after the Greek kerato who means cornea and conus who means cone. This is a corneal dystrophie of the cornea causing a thinning of the stroma and progressive deformation of the cornea, which makes bulge forwardly, creating a disturbance of visual function.
There are two main forms: keratoconus (1/1000) and pellucid marginal degeneration (DMP). Keratoconus develops between puberty and tends to stabilize towards the end of the thirties. For the DMP, it usually starts during the thirties and stabilizes later.
The evolution of keratoconus is asymmetric and unpredictable. Contact lenses can improve vision at the beginning of the disease, however, when there is progress, these become increasingly difficult to tolerate. Until recently, the last resort was corneal transplantation (replacing the transparent part of the eye). A similar condition can develop after a LASIK ectasia post-Lasik (1/5000).