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Oxygen has been shown to be harmful to many tissues in the body via the formation of oxygen free radicals through normal metabolic processes. The higher PO2 used in hyperbaric oxygen therapy is thought to increase the production of these harmful, reactive species. The body has natural defense mechanisms to protect against free radical damage. Superoxide dismutase, a protective enzyme, acts to remove superoxide radicals and other reactive products of metabolism. Under hyperoxic conditions, it is thought that the increased production of these reactive species overwhelms the body's natural defense mechanisms which lead to oxygen toxicity and cellular damage. The toxic effects of hyperbaric oxygen have damaging effects on the eye, particularly the lens. The most commonly reported symptoms are eyelid twitching, blurry vision, and visual-field disturbances. Many of the reported symptoms have been attributed to oxygen toxicity of the lens which leads to various complications such as myopia and the formation and progression of cataracts. The majority of ocular side effects are reversible, but some of the effects of prolonged therapy can be irreversible. This activity reviews the hyperbaric related myopia and cataract formation and discusses the role of the interprofessional team in educating patients on the potential for these side effects. Objectives: Review the potential damaging effects of oxygen on the tissues. Describe the potential damaging effects of oxygen on the eye. Outline the reversible eye related side effects of oxygen. Explain hyperbaric related myopia and cataract formation and address the role of the interprofessional team in educating patients on the potential for these side effects. Access free multiple choice questions on this topic.

Oxygen has been shown to be harmful to many tissues in the body via the formation of oxygen free radicals through normal metabolic processes. The higher PO2 used in hyperbaric oxygen therapy is thought to increase production of these harmful, reactive species. The body has natural defense mechanisms to protect against free radical damage. Superoxide dismutase, a protective enzyme, acts to remove superoxide radicals and other reactive products of metabolism. Under hyperoxic conditions, it is thought that the increased production of these reactive species overwhelms the body's natural defense mechanisms which leads to oxygen toxicity and cellular damage.[1][2][3] The toxic effects of hyperbaric oxygen have damaging effects on the eye, particularly the lens. The most commonly reported symptoms are eyelid twitching, blurry vision, and visual-field disturbances. Many of the reported symptoms have been attributed to oxygen toxicity of the lens which leads to various complications such as myopia and the formation and progression of cataracts. The majority of ocular side effects are reversible, but some of the effects from prolonged therapy can be irreversible.[4][5][6]

It is now clear that HBO therapy does have detrimental effects on the eye. However, this appears to be true after repeated sessions and there is little evidence to show that a single session can cause glaucoma or cataracts. Nevertheless, patients who undergo repeated HBO treatments need to follow up with an ophthalmic nurse, ophthalmologist  and the internist to assess for eye symptoms. The preventable risk factors for eye disease should be minimized and the patient encouraged to eat healthy, wear sunglasses when going outdoors and avoid smoking. Healthcare workers should not empirically prescribe HBO treatment without a valid reason.