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Hyperoxic myopia in a closed-circuit mixed-gas scuba diver
1Naval Special Warfare Command, Detachment Pensacola, Florida, USA.
Summary
Scuba divers using mixed gas experienced a myopic shift due to hyperoxic myopia from prolonged oxygen exposure. This reversible vision change highlights risks of oxygen toxicity in intensive diving.
Area of Science:
- Diving Medicine
- Ophthalmology
- Hyperbaric Physiology
Background:
- Closed-circuit mixed-gas scuba diving involves breathing a nitrogen-oxygen mix at elevated pressures.
- Maintaining a constant partial pressure of oxygen (PPO2) is crucial for diver safety and physiological stability.
- Previous understanding of oxygen toxicity risks in diving primarily focused on pulmonary effects.
Observation:
- A significant myopic shift was observed in a scuba diver after 18 days of diving.
- The diver used a nitrogen-oxygen mix with a constant PPO2 of 1.3 atm abs and averaged 4.04 hours per day.
- This visual change, a form of hyperoxic myopia, resolved within one month post-diving.
Findings:
- The observed myopic shift is attributed to lenticular oxygen toxicity.
- Subsequent dives with the same gas mixture and similar profiles revealed myopic shifts in multiple divers.
- This indicates a consistent risk associated with the specified diving conditions.
Implications:
- Divers and diving communities must be aware of the potential for both lenticular and pulmonary oxygen toxicity.
- Intensive diving at PPO2 levels between 1.3-1.6 atm abs carries significant risks.
- Further research and safety protocols are needed to mitigate these risks in deep or prolonged diving operations.