Abstract
Purpose: :
One of our previous clinical studies has shown that patients who wore high-protein uptake lenses (e.g., Acuvue 2) much preferred Optifree Express (OFX), which provided better cleaning and comfort; however, Optifree (OF) was overwhelmingly preferred by subjects wearing low-protein uptake lenses (e.g., Focus N/D). We hypothesize that one of the reasons for these preferences is related to different protein removal efficiencies among the multi-purpose solutions (MPS). To test this hypothesis, we examined the efficiency of 7 commercial MPS in removal of proteins adsorbed on well-characterized model silica surface.
Methods: :
An optical waveguide lightmode spectroscopy (OWLS; MicroVacuum Ltd, Budapest, Hungary) was employed to determine adsorbed-layer mass and thickness on a silica-coated optical waveguide (OW). The OWs were first equilibrated with a baseline buffered saline solution, pH 7.1. Then the solution of protein (HEW Lysozyme) in the same buffer was pumped through flow cell and adsorption of protein was monitored. After 22 hrs. of protein adsorption, pure buffer was pumped through the cell for 2 hrs. to remove all the protein from bulk and to desorb loosely bound protein from the OW surface. The next step involved the flow of MPS through the cell for 20 min. followed by washout with buffer for 1-2 hrs.
Results: :
80%, 42%, 20%, 17 %, 11.5%, 4.5%, and 2.0% of the adsorbed Lysozyme was removed with OFX, OFR, AQuify, ReNu No Rub, OF, Complete Moisture, and 0.18% wt Tetronic 1304, respectively.