Novel Role of Molecular Hydrogen: The End of Ophthalmic Diseases?

Molecular hydrogen (H) is a colorless, odorless, and tasteless gas which displays non-toxic features at high concentrations. H can alleviate oxidative damage, reduce inflammatory reactions and inhibit apoptosis cascades, thereby inducing protective and repairing effects on cells. H can be transported into the body in the form of H gas, hydrogen-rich water (HRW), hydrogen-rich saline (HRS) or H produced by intestinal bacteria. Accumulating evidence suggest that H is protective against multiple ophthalmic diseases, including cataracts, dry eye disease, diabetic retinopathy (DR) and other fields. In particular, H has been tested in the treatment of dry eye disease and corneal endothelial injury in clinical practice. This medical gas has brought hope to patients suffering from blindness. Although H has demonstrated promising therapeutic potentials and broad application prospects, further large-scale studies involving more patients are still needed to determine its optimal application mode and dosage. In this paper, we have reviewed the basic characteristics of H, and its therapeutic effects in ophthalmic diseases. We also focus on the latest progress in the administration approaches and mechanisms underlying these benefits.