Keratoconus
（重定向自Keratoconus posticus circumscriptus）
![](/Images/godic/202501/22/Keratoconus_eye4205.jpg")
![A simulation of the multiple images seen by a person with keratoconus.](/Images/godic/202501/22/Kc_simulation4205.jpg")
![Multiple images made by extremely high contrast light sources as seen by a person with keratoconus. left to right: healthy eye, uncorrected keratoconus vision, mostly corrected keratoconus vision with contact lenses.](/Images/godic/202501/22/Kc_simulation24205.png")
![A schematic diagram showing change in cornea](/Images/godic/202501/22/Keratoconus.svg4205.png")
Keratoconus (KC, KTCN) is a degenerative disorder of the eye in which structural changes within the cornea cause it to thin and change to a more conical shape than the more normal gradual curve. Keratoconus can cause substantial distortion of vision, with multiple images, streaking and sensitivity to light all often reported by the person. It is typically diagnosed in the person's adolescent years. If both eyes are significantly affected, the deterioration in vision can affect the person's ability to drive a car or read normal print.