Molecular Hydrogen Effectively Heals Alkali-Injured Cornea via Suppression of Oxidative Stress

The aim of this study was to examine the effect of molecular hydrogen (H(2)) on the healing of alkali-injured cornea. The effects of the solution of H(2) in phosphate buffered saline (PBS) or PBS alone topically applied on the alkali-injured rabbit cornea with 0.25 M NaOH were investigated using immunohistochemical and biochemical methods. Central corneal thickness taken as an index of corneal hydration was measured with an ultrasonic pachymeter. Results show that irrigation of the damaged eyes with H(2) solution immediately after the injury and then within next five days renewed corneal transparency lost after the injury and reduced corneal hydration increased after the injury to physiological levels within ten days after the injury. In contrast, in injured corneas treated with PBS, the transparency of damaged corneas remained lost and corneal hydration elevated. Later results—on day 20 after the injury—showed that in alkali-injured corneas treated with H(2) solution the expression of proinflammatory cytokines, peroxynitrite, detected by nitrotyrosine residues (NT), and malondialdehyde (MDA) expressions were very low or absent compared to PBS treated injured corneas, where NT and MDA expressions were present. In conclusion, H(2) solution favorably influenced corneal healing after alkali injury via suppression of oxidative stress.