Protein deposits on individual hydrophilic contact lenses: effects of water and ionicity

Chemical procedures have been developed for eluting deposits from individual hydrophilic contact lenses using combinations of solvents. Total protein was determined as a function of the FDA-proposed classification system for hydrogel lenses. Group IV lenses (high water content, ionic matrix polymers) contained the greatest amount of protein deposits, while group I lenses (low water content, non-ionic polymers) contained the least. Group II lenses (high water content, non-ionic polymers) showed an affinity for protein greater than groups I and III (low water content, ionic polymer) but significantly less than group IV. The necessary basic conditions for maximal protein contamination of hydrophilic contact lenses seems to be created through a combination of an ionic polymer existing in a polar, high water content milieu.