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Michael Foster, Alan Landers, Manal Gabriel, Jennifer Lane, Walter Nash; Tear Film Proteins Strongly-Adherent to a Non-Ionic Silicone Hydrogel Contact Lens Across the Wear Cycle. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5489.
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To evaluate the difference between day one versus day twenty-eight levels of eight strongly-adherent contact lens-adsorbed protein analytes (lysozyme, lactoferrin, lipocalin, free κ/λ Ig light chain, IgA heavy chain, monomeric IgA, secretory component, and total protein) among a group of non-ionic silicone hydrogel contact lens wearers.
Lenses were collected from subjects aseptically and stored at below -20 degrees C. All subjects wore the same non-ionic silicone hydrogel lens material and used the same lens care regimen. Lenses were equilibrated to ambient temperature and rinsed in 2 mL of phosphate buffered saline for 5 minutes with agitation. The lens was extracted in SDS/urea buffer. The extraction buffer was concentrated, labeled with a fluorimetric dye, and subjected to microfluidic electrophoresis.
Total strongly-adsorbed protein decreased between wear from day-one to day-twenty eight, 1.64 to 1.22 µg/lens (p=0.004, Mann-Whitney), respectively. Among the other resolved proteins lysozyme, lactoferrin, lipocalin, κ/λ Ig light chain, and monomeric IgA also exhibited statistically-significant decreases over the wear cycle (p<0.05). Most significant was the 3-fold drop in strongly-adherent monomeric IgA (p=0.000).
A statistically-significant decline in total strongly-adherent protein from lenses worn between day-one and day-twenty-eight occurs in parallel to a general decline in patient-reported comfort scores. This unexpected finding seems to contradict the hypothesis that strongly-adherent protein levels increase with wear time. An alternate hypothesis is that other non-protein components of the tear film (possibly cholesterol or cholesterol esters) serve to displace initially strongly-adherent protein molecules as the wear cycle progresses. A general increase in the inflammatory environment of the ocular surface may accompany the 3-fold drop in monomeric IgA. IgA is generally considered as a non- or anti-inflammatory antibody isotype and therefore may be correlated with the observed decreased in comfort over the wear period.
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