An apparatus (100) to maintain an environment over an anterior surface of a patient eye can include an enclosure (110) sized and shaped to be seated about the patient eye to form a cavity (112) within the enclosure. The enclosure can be configured to contain a fluid other than ambient air in contact with the patient eye. The apparatus can include a fluid regulator (1209) in communication with the enclosure, where the fluid regulator can be configured to regulate the composition of the fluid contained within the enclosure.
