Impact of a rinse step on protein removal from silicone hydrogel contact lenses.

PURPOSE: To determine the impact of the rinse step in "no rub" contact lens care systems relative to its ability to assist in removing loosely associated and bound tear film proteins from a worn silicone hydrogel lens. METHODS: After informed consent, subjects were fitted with lotrafilcon B contact lenses (CIBA Vision). If the fit was acceptable, subjects were asked to wear the lenses on a daily wear basis for 5 (+2, -0) days for an outcome visit. Subjects were instructed to use AQuify Multi-Purpose Disinfecting Solution (CIBA Vision) following the manufacturer's "no rub" instructions. At the outcome visit, contact lenses were then collected by a gloved examiner, with a sterile metal forceps, who rinsed the right lens but did not rinse the left lens on removal from the eyes. Protein was extracted with a 50:50 0.2% trifluoroacetic acid-acetonitrile solution and quantified using a Bradford analyses. RESULTS: Twenty contact lens wearers were enrolled in this study. For the non-rinsed lenses, the first extraction yielded 13.4 +/- 9.2 microg/lens of protein, whereas the second extraction yielded 5.8 +/- 2.8 microg/lens of protein. For the rinsed lenses, the first extraction yielded an average of 3.0 +/- 1.9 microg/lens of protein, whereas the second extraction yielded an average of 4.0 +/- 2.3 microg/lens. Repeated measures analysis of variance showed a significant interaction (F-statistic = 18.9, p < 0.0001) between the rinse of a lens and extraction number. CONCLUSIONS: Rinsing a contact lens after removal from the eye removes well more than one-half of the protein associated with it. Further, to biochemically recover all protein from a silicone hydrogel lens, it may be important to perform more than one chemical extraction from it.