Clinical application of the oxygen transmissibility of powered contact lenses.
Stipulation of the oxygen transmissibility (Dk/L) of a contact lens based upon oxygen permeability (Dk) and nominal lens thickness (L) can be misleading since center thickness, average thickness, and hence Dk/L of a contact lens vary with lens power. While earlier confusion regarding determination of Dk has now been resolved, this data has yet to be fully incorporated into a clinically applicable model. We developed a graphical solution describing variations in Dk/L with power for a representative sample of currently available hydrogel and rigid contact lenses. The Dk/L is found to be optimal for lenses of low minus power (approximately -2.50 D). The model presented here will assist practitioners in assessing the potential oxygen performance of different lens designs with respect to a given power. We advocate that lens manufacturers print the average Dk/L on lens packaging, according to the model described in this paper, along with the parameters that are usually stated.
Brennan
N A
NA
Department of Optometry, University of Melbourne, Parkville, Victoria, Australia.
Efron
N
N
Weissman
B A
BA
Harris
M G
MG
D003263:Contact Lenses, Hydrophilic; D006801:Humans; D008954:Models, Biological; D055095:Optics and Photonics; D010100:Oxygen / Q000032:analysis*
D010100:Oxygen