In Vivo Oxygen Uptake into the Human Cornea

It should be noted that the absolute value that we favor for human corneal oxygen uptake is based on saline reservoirs (see the report of Hill and Fatt ¹ ) and is ∼5 μL/cm²/hour. The model of Takatori et al. ² relates to a membrane-corneal contact reservoir system, and is dependent upon their particular premises and assumptions. According to Takatori et al., ² “Fatt and coworkers assumed that oxygen initially in the protective membrane diffused into the cornea with no oxygen flux into the cathode.^39–41” Yet, in the report of Hill and Fatt (Fig. 2 in their report), tests made for that cathode flux showed its effect to be negligible. ¹ If there is significant oxygen flux into the cathode, its magnitude and effects on the probe's intended function should be measurable. However, the authors offer “schematic” representations when addressing this point in their Figures 1 and 2. Absence of those physical measurements, made on this probe system (with original cathode diameter and membrane thickness), does not meet an evidence-based standard for support of their “schematic” assumptions.