RGP lenses are made from a stiff, oxygen-permeable material. They do not flex with blinks like soft contact lenses conform to the eye’s surface. This characteristic gives RGP lenses greater definition and sharper vision. Because they maintain their shape, RGP contact lenses are particularly useful for correcting astigmatism-a condition in which the cornea is irregularly shaped, so it can cause your sight to be blurry or distorted.