It is well known that conventional contact lenses cause a corneal haze. Recently it has been shown that contact lenses affect the cornea by depriving it of its normal access to oxygen, and that this effect can be abolished if an adequate corneal oxygen supply is made available.* In addition, the effects of contact lenses on the optical properties of the cornea have been duplicated in man by exposing the eye to an oxygen-free atmosphere, thus inducing a relatively anaerobic condition for the cornea. On the basis of these experiments, it was suggested that the cornea maintains its normal water balance by an active metabolic process which requires oxygen, part of which is obtained from air, and that conventional contact lenses, by interfering with the usual corneal access to oxygen, halt the normal dehydrating mechanism. This results in corneal hydration, which causes the observed increase in its thickness and turbidity.
SMELSER GK, CHEN DK. Physiological Changes in Cornea orneu induced by Contact Lenses. AMA Arch Ophthalmol. 1955;53(5):676-679. doi:10.1001/archopht.1955.00930010684009