Quantitative cleaning efficacy evaluation methods with protein and lipid lens soiling models.

We developed a nondestructive, quantitative method for evaluating the cleaning efficacy of rigid gas permeable contact lens care systems. Simulated tears prepared with lysozyme, albumin, and calcium ions were applied to rigid gas permeable lenses as a protein soiling model, and a mixture of grease and unsaturated fat was applied as a lipid soiling model. The ComfortCare system (Pilkington Barnes Hind) and the Boston Cleaner and Boston Conditioning Solution (Polymer Technology) were evaluated for their efficacy in removing protein deposits; water was used as a control. The ComfortCare system and the Boston Advance Cleaner and Boston Advance Conditioning Solution were evaluated for their effectiveness in removing lipid deposits; saline was used as a control. Protein deposit level was detected by a densitometer at the absorbance of 280 nm. The lipid deposit level was evaluated by the absorbance of the fluorescence at 430 nm using the same densitometer with a fluorescence accessory. The two test systems demonstrated a significantly higher cleaning efficacy than the control for both soiling models. The methods provide quantitative measurements and therefore can be analyzed statistically for screening or comparison purposes.