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Jonathan William Brugger, Anita Gupta, Barbara Shykoff, John Florian; Hyperoxic Myopia: A Prospective Study of Twelve Divers with Six Hours of Exposure to 1.35 ATM PO2 for Five Consecutive Days. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2176.
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© ARVO (1962-2015); The Authors (2016-present)
Hyperoxic myopia is a phenomenon associated with prolonged exposure to an increased partial pressure of oxygen (PO2) resulting in a myopic shift of refractive error. This has been described in patients undergoing hyperbaric oxygen therapy and in divers exposed to high PO2. The mechanism of action for hyperoxic myopia is not understood. This prospective study collected ocular data in healthy divers exposed to 1.35 ATM PO2 at the Navy Experimental Diving Unit to better characterize hyperoxic myopia PO2 thresholds and the mechanism of action.
Twelve healthy healthy U.S. Navy Divers participated in five consecutive days of exposure to 100% Oxygen via surfaced-supplied, open-circuit MK20 breathing apparatuses at the bottom of a 15-foot pool (PO2 of 1.35 ATM) for 6 hours. Prior to diving, and three days after the last dive, subjects had an ocular examination consisting of visual acuity (VA), autorefraction, intraocular pressure (IOP), biometry, and corneal topography. Before and after every dive, subjects had VA, and autorefraction. IOP was measured on the first, third, and fifth day.
Two of the twelve divers had subjective symptoms of blurry vision 2-3 days after the last dive. The first diver had a myopic shift of -0.50 diopters OS via autorefraction and VA change from 20/16 to 20/20-2. The other diver had a myopic shift of approximately -0.25 diopters OU via autorefraction with a VA shift from 20/30-1 to 20/100 OD and 20/20-1 to 20/40 OS. Both subjects had no significant changes in IOP, topography, and biometry measurements and both had spontaneous resolution of their myopia over two to three weeks with no residual symptoms.
Two healthy divers exposed to an increased PO2 (1.35ATM for 30 hours in 5 days) developed symptomatic myopia with no changes in corneal topography and biometry (axial length, lens thickness, aqueous depth). With no appreciable changes in eye structure, a change in refractive index of the lenticular crystalline lens is likely responsible for the myopic shift. Hyperoxic myopia is a risk for those conducting intense diving with a PO2 between 1.3-1.6 ATM and warrants additional studies to better define risk factors, recovery time, mechanism of action, and PO2 thresholds.
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