A single-lens polarographic measurement of oxygen permeability (Dk) for hypertransmissible soft contact lenses.
A novel polarographic apparatus is described that requires only a single soft contact lens (SCL) to ascertain oxygen permeabilities of hypertransmissible lenses. Unlike conventional methods where a range of lens thickness is needed for determining oxygen permeabilities of SCLs, the apparatus described here requires only a single-lens thickness. This is accomplished by minimizing (or completely eliminating) edge effects, boundary-layer resistances, and lens desiccation in the polarographic apparatus. By taking these effects into account, we measure reliable oxygen permeabilities of hypertransmissible SCLs (i.e., above 100 barrer). Results are reported for nine commercial SCLs ranging in permeability from 9 to 180 barrer. Measured single-lens oxygen permeabilities are in excellent agreement with those claimed by commercial manufacturers. Our new single-lens permeameter provides a reliable, efficient, and economical method for measuring oxygen permeabilities of commercial SCLs. The single-lens method offers a potential international standard for measuring oxygen permeabilities of SCLs up to 250 barrer.
Department of Chemical Engineering, University of California, Berkeley, CA 94720-1462, USA. chhabra@berkeley.edu
Mahendra
M
Chhabra
John M
JM
Prausnitz
Clayton J
CJ
Radke
D003263:Contact Lenses, Hydrophilic; D006801:Humans; D010100:Oxygen / Q000378:metabolism*; D010539:Permeability; D011048:Polarography / Q000295:instrumentation / Q000379:methods*; D013696:Temperature
D010100:Oxygen