Keratoconus (ker-uh-toe-KOH-nus) occurs when your cornea — the clear, dome-shaped front surface of your eye — thins and gradually bulges outward into a cone shape.
A cone-shaped cornea causes blurred vision and may cause sensitivity to light and glare. Keratoconus usually affects both eyes and generally occurs in people ages 10 to 25. The condition may progress slowly for 10 years or longer.
Vision problems can be corrected with glasses or soft contact lenses early on in the condition. As keratoconus progresses, you may have to be fitted with rigid gas permeable contact lenses or other types of contact lenses. Advanced keratoconus may require a cornea transplant.