Orthokeratology lens care: Surface treatment by an atmospheric pulsed microwave air plasma jet

Orthokeratology lens (OK lens) is one of the effective tools for myopia correction in adolescents. Currently, the OK lens is maintained by surface treatment of the atmospheric argon plasma jet for wearing comfort, sterilization and cleaning. In order to increase the concentration of reactive species and the convenience of plasma device, an atmospheric pulsed microwave air plasma jet is developed and used to treat the OK lens. The electrical and optical characteristics of the microwave air plasma jet are evaluated by the discharge images, optical emission spectrum (OES), gas temperature and electron density, while the surface physical and chemical characteristics of OK lens are studied by the surface wettability, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The results indicate that the surface wettability of OK lens increases after plasma treatment, while no significant changes in surface morphology are observed. The increase of oxygen-containing groups, decrease of fluorine-containing groups and formation of silicates on the lens surface are the main reasons for the enhancement of hydrophilicity. Surface treatment by pulsed microwave air plasma jet is a promising method for OK lens care, which provids a technical approach for portable lens care devices.