Glossary of Terms
This is the most common corneal dystrophy in the U.S, and is most prevalent in teenagers and adults in their 20s. It happens when the middle of the cornea thins and gradually bulges outward, forming a cone shape. This bulging changes the how the cornea refracts (bends) light, and can cause refractive errors such as nearsightedness and astigmatism. It can also cause swelling and scarring of the cornea, which can harm vision. Keratoconus usually affects both eyes.