Corneal edema with contact lenses under closed-eye conditions

Subjects wore PMMA, CAB, and thin hydrogel contact lenses with their eyes closed for periods of 6 hr. The corneal edema that developed was evaluated by observing the amount of central circular clouding and by measuring the increase in central corneal thickness with a slit-lamp biomicroscope and pachometer. Central circular clouding was greater with the PMMA and CAB lenses than with the thin hydrogel lenses. Corneal thickness increased by different amounts for the three subjects, but the three lens types caused about the same increase in corneal thickness for a given subject.