Your cornea may become hazy or damaged because of disease or injury. Corneal infections caused by inadequately cleaned contact lenses can lead to permanent corneal damage if not treated promptly. Trauma to the eye can likewise permanently injure the cornea, as can certain progressive diseases, such as keratoconus. When the cornea is damaged, it may become swollen or scarred, and its smoothness and clarity may be lost. The scars, swelling or resulting irregular shape cause the cornea to scatter or distort light, resulting in glare or blurred vision. Like a foggy window, light no longer passes through it well, so a blurred image forms in your eye.