An eye treatment positions a mask device over first and second eyes. A posterior side of the mask device is proximate to the face and the anterior side is distal from the face. The mask device includes an outer wall extending between the anterior and posterior sides and defining a chamber extending across the first and second eyes. The anterior side includes a first transmission region that allows a photoactivating light for the first eye to be delivered into a first section of the chamber positioned over the first eye. The anterior side includes a second transmission region that allows a photoactivating light for the second eye to be delivered into the second section positioned over the second eye. The system includes at least one gas source storing a gas that is different than ambient air. The system includes a gas delivery system that delivers the gas into the chamber.
