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C. H. Powell, L. D. Hoong, S. W. Huth; Lipid and Protein Removal from a Silicone Hydrogel Lens (lotrafilcon A) by a Rub versus a No-rub Multipurpose Solution Using Infrared Analysis of Clinically Worn Lenses. Invest. Ophthalmol. Vis. Sci. 2009;50(13):6334.
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The effective reduction of bio-burden (including Fusarium and Acanthamoeba) from lens surfaces by digital rubbing has been well proven. The potential for also removing much smaller entities (e.g. proteins and lipids) by a rub-rinse regimen is a less established but reasonable expectation. This study compares real-world (clinical) cleanliness of a silicone hydrogel lens (Focus Night & Day) used one month in daily wear mode with a rub-regimen MPS (COMPLETE Easy Rub, CER) versus a no-rub-regimen MPS (OPTI-FREE Express, OFX). A Fourier Transform Infrared (FTIR) spectroscopic method is used in quantifying extracted lipid and protein from the lenses.
Lenses were obtained from the same 15 patients (30 eyes) for each regimen from a sequential 30-day daily-wear study with use of a no-rub regimen (with OFX) versus a rub regimen (with CER). The analyst was masked regarding lens treatment. Clinically harvested lenses were each extracted with 2 mL of tert-butyl-methyl ether (TBME). The solvent was evaporated and residue was reconstituted in 50 µL of TBME. A 20-µL portion was spotted onto a thin Teflon film and air dried. The film was scanned by FTIR, and lipid (1725 cm-1) and protein (1545 cm-1) peaks were used for the respective quantifications.
Less than half the levels of both lipid and protein were recovered from lenses used with the rub regimen (CER) than with the no-rub regimen (OFX). Average lipid levels were 3.4µg/lens with rub (CER) and 7.2µg/lens with the no-rub (OFX), while protein levels were 0.7µg/lens with rub (CER) and 2.0µg/lens with no-rub (OFX). Differences were significant or trended toward significance (p0.05).
FTIR analysis of clinically worn Focus Night & Day silicone hydrogel lenses showed significant improvement of lens cleanliness with regards to both lipid and protein by use of a rub-regimen product (CER) versus a no-rub regimen product (OFX). FTIR was assessed to be a viable means of quantifying lipid and protein as general categories of lens deposits.
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