Intacs can greatly improve eyesight. They also can improve a person's tolerance for contact lenses.
The clear front surface of the eye, called the cornea, helps focus light on the retina, to produce clear vision. Blurry vision results if the cornea does not keep its normal shape. For instance, conditions such as keratoconus make the cornea bulge forward. This leads to distorted vision.
People with early keratoconus may have good eyesight with glasses. But, as their eye disease worsens, they most often need a rigid contact lens to improve vision quality. In time, the cornea may become so misshapen or scarred that a contact lens fails to give the desired visual correction.