The “Physiologically Effective” Correlates: pe Dk/L and pe Dk

Introduced here are two predictive parameters, pe Dk/L and pe Dk. The prefix pe ‐ (for physiologically effective) indicates that such values are estimates of lens transmissibility (Dk/L) and material permeability (Dk) and have been derived through a reverse application of the Residual Hypoxia model of Smith, relating corneal response (in hypoxic stress units) to lens transmissibility (Dk/L). Here, using independent databases, physiological responses to simple oxygen pathways (one layer, one material) but of unknown Dk value were entered into that model to estimate the Dk/L and (then by calculation) the Dk value of single vision rigid gas permeable (RGP) contact lenses. Also demonstrated was the application of this strategy for estimation of composite (integrated) Dk/L and Dk values of complex (multi‐layer, multi‐material) oxygen pathways, wherein one or more material Dk values and/or one or more local thickness are unknown.