title: Impact of tear film components on lysozyme deposition to contact lenses.
abstract: OBJECTIVE
  To investigate the impact of lactoferrin and lipids on the kinetic deposition of lysozyme on silicone and conventional hydrogel lenses, using a complex artificial tear solution (ATS).
  
  
  METHODS
  Two silicone hydrogel lenses (AIR OPTIX AQUA; lotrafilcon B and ACUVUE OASYS; senofilcon A) and two conventional hydrogel lenses (ACUVUE 2; etafilcon A and PROCLEAR; omafilcon A) were investigated. Lenses were incubated in four different solutions: a complex ATS consisting of various salts, lipids, proteins, and mucins, an ATS without lactoferrin (ATS w/o Lac), an ATS without lipids (ATS w/o Lip), and an ATS without lactoferrin and lipids (ATS w/o Lac & Lip), each containing 2% radiolabeled (125I) lysozyme (1.9 mg/ml). After each time point (4, 12 h and 1, 2, 3, 5, 7, 14, 21, 28 days), the amount of lysozyme per lens was quantified.
  
  
  RESULTS
  After 28 days, lotrafilcon B lenses incubated in ATS deposited significantly less lysozyme (9.7 ± 1.4 μg) than when incubated in solutions not containing lactoferrin and lipids (more than 11.8 μg) (p < 0.001). Lysozyme uptake to senofilcon A lenses was higher in ATS w/o Lip (5.3 ± 0.1 μg) compared with other solutions (less than 3.9 μg) (p < 0.001). Etafilcon A lenses deposited the most lysozyme in all four solutions compared with the rest of the lens types (p < 0.001). For etafilcon A lenses, less lysozyme was deposited when incubated in ATS w/o Lip (588.6 ± 0.4 μg) compared with the other solutions (more than 642.6 μg) (p < 0.001). Omafilcon A lenses in ATS w/o Lac accumulated significantly less lysozyme (12.8 ± 1.0 μg) compared with the other solutions (more than 14.2 μg) (p < 0.001).
  
  
  CONCLUSIONS
  An ATS containing lactoferrin and lipids impacts lysozyme deposition on both silicone and conventional hydrogel contact lenses. When performing in vitro experiments to study protein deposition on contact lenses, more complex models should be used to better mimic the human tear film.
authors.affiliation: Centre for Contact Lens Research, School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada. akl2ng@uwaterloo.ca
authors.forename: Alan
authors.initials: A
authors.lastname: Ng
authors.forename: Miriam
authors.initials: M
authors.lastname: Heynen
authors.forename: Doerte
authors.initials: D
authors.lastname: Luensmann
authors.forename: Lyndon
authors.initials: L
authors.lastname: Jones
mesh_terms: D000327:Adsorption; D003263:Contact Lenses, Hydrophilic; D006801:Humans; D007781:Lactoferrin / Q000032:analysis*; D008055:Lipids / Q000032:analysis*; D008247:Lysosomes / Q000378:metabolism*; D012825:Silicon; D013666:Tears / Q000737:chemistry*
chemical_list: D008055:Lipids; D007781:Lactoferrin; D012825:Silicon