Radiochemical studies on contact lens soilation. II. Lens uptake of cholesteryl oleate and dioleoyl phosphatidylcholine.

Employing an artificial tear preparation composed of six proteins and six lipids as a deposit model, uptake of the lipids 3H-cholesteryl oleate and 14C-dioleoyl phosphatidylcholine was measured on contact lenses representative of the four FDA hydrogel groups and on select RGP lenses. Cholesteryl oleate uptake after 24 h at 37 degrees C generally was less than 1 microgram/lens although occasionally reaching 1-2 micrograms. DuraSoft 3 lenses (Group IV) accumulated the deposits in greater amounts (p = 0.04) with other lens groups not differing significantly from each other. Ionic DuraSoft 2 and 3 lenses bound more phosphatidylcholine (also < 1 microgram) than other lens groups, possibly reflecting an interaction between the positively charged choline residue and the negative surface of the lens. Lysozyme deposition, measured simultaneously with cholesteryl oleate, bound to a far greater extent to Group IV lenses (e.g., DuraSoft 3, mean surface deposit 279 micrograms) than to other lens types (p < 0.01). Multiple application of the artificial tear solution did not produce a statistically significant increase in cholesteryl oleate accumulation.