Abstract
The incidence of dry eye disease is increasing worldwide because of the aging population and increasing use of information technology. Dry eye disease manifests as tear-layer instability and inflammation caused by osmotic hypersensitization in tear fluids; however, to our knowledge, no agent that treats both pathologies simultaneously is available. Molecular hydrogen (H(2)) is known to be effective against various diseases; therefore, we aimed to elucidate the effects of H(2) on tear dynamics and the treatment of dry eye disease. We revealed that administering a persistent H(2)-generating supplement increased the human exhaled H(2) concentration (p < 0.01) and improved tear stability (p < 0.01) and dry eye symptoms (p < 0.05) significantly. Furthermore, H(2) significantly increased tear secretion in healthy mice (p < 0.05) and significantly suppressed tear reduction in a murine dry eye model (p = 0.007). H(2) significantly and safely improved tear stability and dry eye symptoms in a small exploratory group of 10 human subjects, a subset of whom reported dry eye symptoms prior to treatment. Furthermore, it increased tear secretion rapidly in normal mice. Therefore, H(2) may be a safe and effective new treatment for dry eye disease and thus larger trials are warranted.