Applications of ionized gases in medicine: towards a treatment of eye-surface infections

In recent years the study of the interaction of ionized gases (plasma) with living matter has started to attract considerable interest, due to the potential medical applications. In this work we present a feasibility study on the use of a low power, atmospheric pressure plasma source for the treatment of eye surface infections. The plasma is produced by a RF voltage applied to a flow of helium mixed with air. The power dissipated on the plasma is less than 1 W, so that the gas is not appreciably heated. The plasma induces the formation of active chemical species, such as atomic oxygen and OH radical, which are convected by the helium flow to the substrate to be treated. In-vitro studies show that this enriched flow is able to kill microbes and other pathogens responsible for ocular infections. On the contrary, cultured cells respond to the oxidative stress induced by the active species through the activation of defense mechanisms which allow a high degree of survival. Thus, it appears that a treatment of this kind might cure the infection without harming the ocular surface. Specific tests have also excluded the possibility that genetic damage is induced in the cells.