Wearing contact lenses for long periods of time or while sleeping can prevent the cornea from coming into contact with the air, resulting in a lack of oxygen in the eyes, similar to the “plateau reaction” of the human body, resulting in red eyes, eye pain and blurred vision. Prolonged contact lens wear can lead to dry eye syndrome. The proteins deposited on contact lenses can cause an allergic reaction known as “macropapillary conjunctivitis,” which can be characterized by itchy, burning eyes and a thick, purulent discharge. Improper contact lens removal or wearing contact lenses that do not fit the cornea can cause abrasion of the corneal epithelium and even secondary bacterial and amoebic infections, resulting in irreversible vision loss. Long-term contact lens wear can also cause paralysis of the nerve endings in the cornea, resulting in decreased perception of the cornea.