Oxygen Tension underneath Contact Lenses by Fluorescence Lifetime Sensing

Abstract

The cornea is the main refracting element of the eye, and hence its transparency is critical for perfect vision. The cellular layers of the cornea contribute to the maintenance of transparency, and their energy needs are met partly by oxidative phosphorylation. The epithelium at the anterior surface derives O₂ from the atmosphere when eyes are open and from the conjunctival circulation when the eyes are closed. The endothelium, which faces the anterior chamber, extracts its need from the circulating aqueous humor. During contact lens wear, depending on the O₂ transmissibility of the lens, transcorneal O₂ dynamics could be affected. An assessment of O₂ tension (pO₂) underneath the contact lens would help evaluate contact lens design. The information can be helpful to determine specific O₂ consumption rates by the different layers of the cornea. This paper describes various techniques for measuring pO2 underneath contact lenses and corresponding methods for determining O2 consumption rates of the cellular layers.