Corneal edema in divers wearing hard contact lenses.

Polymethylmethacrylate (hard) contact lens-wearing Navy divers involved in hyperbaric research complained of ocular discomfort, halos, specular highlights, and decreased visual acuity during and immediately after the decompression phase of dry chamber dives. These symptoms were related to bubbles in the tear film between the cornea and hard contact lens. The bubbles developed during the decompression phase of the dive and represented the trapping (by the hard contact lens) of nitrogen outgassing from the cornea and precorneal tear film. The bubbles effected nummular patches of corneal epithelial edema persisting up to two hours after diving. Gas trapping and corneal edema were not observed in uncovered corneas or corneas covered with membrane lenses.