Corneal deswelling response to hard and hydrogel extended wear lenses.

The amount of initial corneal swelling and the time course of corneal deswelling were measured after overnight wear of several types of hard and hydrogel lenses. Deswelling occurred in the right eye with the lens still on the cornea. In the left eye the lens was removed at eye opening and left off the cornea during deswelling. For lenses of equal nominal oxygen transmissibility, hard lenses initially induced greater corneal swelling than hydrogel lenses after overnight wear. The rate of deswelling during the first 15 min after hard lens wear was significantly greater than a comparable time period after hydrogel lens wear both with the lenses on and off the eye during deswelling. After the initial 15 min of eye opening, no significant difference in the deswelling rates with hard or hydrogel lenses could be shown under either deswelling condition.