Dry eye syndrome (DES), also known as keratoconjunctivitis sicca (KCS), is the condition of having dry eyes. Other associated symptoms include irritation, redness, discharge, and easily fatigued eyes. Blurred vision may also occur. The symptoms can range from mild and occasional to severe and continuous. Scarring of the cornea may occur in some cases without treatment. Dry eye occurs when either the eye does not produce enough tears or when the tears evaporate too quickly.