title: In Vitro Cholesterol Deposition on Daily Disposable Contact Lens Materials.
abstract: OBJECTIVE
  The goal of this study was to analyze how various incubation times affect the uptake of cholesterol on silicone hydrogel (SH) and conventional hydrogel (CH) daily disposable (DD) contact lens materials using an in vitro radiochemical detection method.
  
  
  METHODS
  Three SH (somofilcon A, delefilcon A, and narafilcon A) and four CH (etafilcon A, nesofilcon A, ocufilcon A, and nelfilcon A) contact lenses were incubated in an artificial tear solution that contained major tear film components and a portion of radioactive C-cholesterol. Lenses (N = 4) were incubated for four incubation times (2, 6, 12, or 16 h) to assess the effects on cholesterol deposition. Subsequent to the incubation, the lenses were extracted using 2:1 chloroform:methanol, and the extracts were analyzed in a beta counter and (in nanograms per lens) extrapolated from standard curves.
  
  
  RESULTS
  In general, cholesterol deposited statistically significantly more on SH lenses than CHs (p ≤ 0.033), with the exception of somofilcon A and nesolfilcon A materials (p = 0.067). Within the SH materials, narafilcon A accumulated the largest quantity of cholesterol (p < 0.05) and somofilcon A the lowest (p < 0.05). The uptake of cholesterol ranged from 22.63 ± 2.98 ng/lens to 97.94 ± 4.18 ng/lens for all lens materials. The accumulation of cholesterol was shown to be continuous throughout the 16 h of incubation, without reaching a plateau (p < 0.001).
  
  
  CONCLUSIONS
  For the periods that DD lens materials are worn, cholesterol deposits significantly more onto SH contact lenses than CHs. This could have implications for wearers who have higher levels of lipid in their tears that are fitted with SH DD materials.
authors.affiliation: *MSc †PhD, BSOptom, MSc, FAAO ‡PhD, FCOptom, FAAO Centre for Contact Lens Research, School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada (all authors).
authors.forename: Hendrik
authors.initials: H
authors.lastname: Walther
authors.forename: Lakshman
authors.initials: L
authors.lastname: Subbaraman
authors.forename: Lyndon W
authors.initials: LW
authors.lastname: Jones
mesh_terms: D002784:Cholesterol / Q000378:metabolism*; D003263:Contact Lenses, Hydrophilic; D004209:Disposable Equipment; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D050356:Lipid Metabolism; D065346:Lubricant Eye Drops; D012828:Silicones; D013997:Time Factors
chemical_list: D065346:Lubricant Eye Drops; D012828:Silicones; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D002784:Cholesterol