Corneal edema with hydrogel lenses and eye closure: time course

Central corneal thickness changes during the wearing of hydrogel lenses under closed-eye conditions were measured for two subjects. Each wore an investigational ultrathin Bausch & Lomb Soflens contact lens (series X-176) on one eye only under closed-eye conditions for periods ranging from 30 min to 6 hr. The other eye served as a control. Corneal thickness of the control eyes increased gradually and reached a maximum increase of about 4% at the end of the 4-hr wearing trial. Corneal thickness in the experimental eyes also increased with wearing time during the first 4 hr and then remained fairly constant up to a wearing time of 6 hr. The maximum thickness increases for the two subjects were 9.8 and 9.1%, respectively. About 80% of the maximum corneal thickness change was present after 3 hr of closed-eye contact lens wear. The corneal thickness in the control eye returned to baseline 80 min after removal of the contact lens. Corneal thickness of one experimental eye returned to baseline 2 hr after the contact lens was removed.