Success with extended wear contact lenses has been hampered by various limitations associated with conventional hydrogels. Hypoxia has long been known as a contributing factor in many adverse corneal responses to contact lens wear, particularly extended contact lens wear. Efforts to increase the oxygen available to the cornea (Dk/t) via increased water content (Dk) and decreased thickness (t) have been insufficient to sustain successful extended wear by the majority of corneas. New efforts to raise oxygen transmissibility by incorporating highly oxygen permeable silicone into the soft contact lens matrix have dramatically increased Dk/t. The purpose of this study was to compare the corneal swelling association with overnight wear of a silicone hydrogel lens to that associate with a conventional extended wear hydrogel.

Overnight corneal swelling is a direct measure of the effect of oxygen deprivation on an individual cornea. These results show that in addition to better lens movement the balafilicon A lens resulted in overnight corneal swelling levels that were significantly reduced relative to conventional extended wear hydrogel lenses and were similar to levels reported for non-lens wearers.