Effects of hyperbaric air pressure on keratometry

Following reports of vision blur by scuba divers at depth below 100 feet, keratometric readings were taken on volunteers inside a hyperbaric chamber at the USAF School of Aerospace Medicine. It was found that as the pressure within the chamber increased, the corneal reading showed an increased dioptric value. This change in refractive condition also occurred in measurement on test steel balls. Whether this dynamic response was due to increased atmospheric index, or displacement of instrument optics, was explored.