What is the cornea? The cornea is the clear front window of the eye. It transmits light to the interior of the eye allowing us to see clearly. Corneal injury, disease, or hereditary conditions can cause clouding, distortion, and scarring. Corneal clouding blocks the clear passage of light to the back of the eye, reducing sight sometimes even to the point of blindness. In addition, corneal injury and disease can be very painful. What causes corneal disease and degeneration? Infections, whethe