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EB Hume, ME Tan, A Parmar, MD P Willcox; Secretory Phospholipase A2 levels in Tears and Lens Extracts During Contact Lens Wear . Invest. Ophthalmol. Vis. Sci. 2002;43(13):71.
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Purpose: Secretory phospholipase A2 (sPLA2) is a potent antibacterial enzyme present in tears. This enzyme has been found to rapidly kill S. aureus in vitro. The first aim of our investigation was to determine whether levels of sPLA2 in tears were altered during contact lens wear. The second aim was to determine what extent sPLA2 is adsorbed to different contact lens types during daily and extended contact lens wear. Method: Contact lenses used were ionic (Etafilcon A) and non-ionic (Polymacon) high water content soft contact lenses. Contact lenses were worn for six hours (n=39) or six nights on an extended wear schedule (n = 25). Worn contact lenses were removed and extracted for protein and active enzyme estimations. Tears (n=39) prior to the six hour contact lens wear study and prior to lens removal were collected. Levels of sPLA2 were measured using an enzyme immunoassay kit. Activity of sPLA2 from samples were quantified using a fluorescent labeled sPLA2 substrate (bis-BIODIPY-FLC11-PC, Molecular Probes). Results: There was no significant difference in tear levels of sPLA2 from Etafilcon A or Polymacon daily contact lens wearers. Daily wear of Etafilcon A contact lenses adsorbed 8.1 ng/lens of sPLA2 and daily wear of Polymacon contact lenses adsorbed significantly less sPLA2 at 5.7 ng/lens, p<0.05. Extended wear Etafilcon A lenses adsorbed 11 ng/lens of sPLA2 whereas extended wear Polymacon lenses adsorbed a significantly lower level of sPLA2 (6.5 ng/lens, p< 0.05). Activity levels of the enzyme correlated with protein amounts from lenses. Conclusion: Etafilcon A contact lenses adsorbed more sPLA2 than Polymacon contact lenses, this amount increases over the wear schedule. The sequestering of this anti-bacterial agent from the tear film on to the contact lens may be protective for the cornea against Staphylococcal infection.
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