The change in shape and thinning of the cornea impairs the ability of the eye to focus properly, causing poor vision. In advanced cases, some patients may develop scarring in the cornea, which can make the sight blurred by reducing the amount of light which can enter the eye.
In the early stages, spectacles or soft contact lenses may adequately correct vision. As the cornea becomes thinner and steeper, rigid gas permeable (RGP) contact lenses are often required to correct vision. In very advanced cases, where contact lenses fail to improve vision, a corneal transplant may be needed.