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W. L. Nash, C. Amos, F. P. Carney; Factors That Influence the Adsorption of Protein and Lipid to Silicone Hydrogel Lenses After 2 Weeks of Daily Wear. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5410.
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To investigate the major factors that determine protein and lipid deposition on 4 major silicone hydrogel lenses.
Lenses were recovered from wearers that had worn either galyfilcon A (ACUVUE ADVANCE®,TM), senofilcon A (ACUVUE OASYS®,TM), lotrafilcon B (O2OPTIXTM) or balafilcon A (PUREVISION®) for 2 weeks on a daily wear basis, using Clear Care®. Lenses were removed with powder free latex gloves and rinsed in saline to remove any tear carry over. Each lens type was separated into 2 groups. 20 lenses were extracted for lipid with a chloroform : methanol (1:1) extraction procedure and assayed for total cholesterol using a commercially available assay (Cayman). The remaining 10 lenses were extracted for total protein using acetonitrile : trifluoroacetic acid: water (499:1:500) mixture, followed by a BCA assay. All data are expressed in µg/lens.
Overall lotrafilcon B showed lower adsorption of cholesterol (2.04±1.4; p<0.05). There was no statistical difference between balafilcon A (3.1±1.2), galyfilcon A (3.83±1.6) and senofilcon A (3.1±1.8) in the amount of cholesterol adsorbed after 2 weeks. Protein adsorption showed greater patient to patient variability. Balafilcon A showed significantly greater protein deposition compared to all other lenses (110.1±26.1; p<0.05). Although there was no statistical difference between these 3 lenses, lotrafilcon B showed lower total protein ranging from 60% undetectable amounts (UD) to 10 µg/lens compared to galyfilcon A (range 20% UD to 17 µg/lens) and senofilcon A (range 40% UD to 25 µg/lens. The ranking order in terms of total deposition from most to least was balafilcon A > galyfilcon A ≥ senofilcon A > lotrafilcon B.
Due to such a high variation in protein deposition within a specific lens type as well as the significant difference in adsorption between balafilcon A and all other lenses, it appears that a patient factor and lens material are both dominant factors in determining levels of deposition. However, in lipid deposition lens material as well as tear/surface interfaces seems to be the greater driving force. The impact of this fouling on clinical outcomes is being investigated further.
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