Adverse effects of contact lens wear during decompression

The effects of corneal contact lens wear during and after exposures for 30 minutes to a depth of 45.5 m (150 ft of sea water) or an altitude of 11,277 m (37,000 ft) were studied. Subjects wore either membrane (soft) lenses or one of two types of polymethylmethacrylate (hard) lenses: fenestrated (0.4-mm hole in the center) or nonfenestrated. During and after decompression from the dive, subjects wearing nonfenestrated polymethylmethacrylate lenses experienced ocular symptoms, the result of corneal epithelial edema caused by formation and trapping of nitrogen bubbles in the precorneal tear film. No bubbles, or only a few miniscule ones, and no symptoms were present when lenses were not worn during the dive or at a high altitude. The reasons why gas trapping and corneal edema do or do not occur are discussed and recommendations for contact lens wear are proposed.