Retinal vascular changes after treatment with hyperbaric oxygen.

A healthy 44-year-old man, who accompanied patients with multiple sclerosis as an attendant into a pressure chamber for hyperbaric oxygen treatment at 203 kPa (2 atm) absolute pressure, used a spare 100% oxygen mask himself for one hour on two occasions, and later noticed a field defect in his left eye. The vasoconstrictive, and consequent possible ischaemic, effects of hyperbaric oxygen are discussed, and the sensitivity of the retinal vasculature to hyperbaric oxygen is emphasized.