title: Evidence of lipid degradation during overnight contact lens wear: gas chromatography mass spectrometry as the diagnostic tool.
abstract: OBJECTIVE
  We investigated structural differences in the fatty acid profiles of lipids extracted from ex vivo contact lenses by using gas chromatography mass spectrometry (GCMS). Two lens materials (balafilcon A or lotrafilcon A) were worn on a daily or continuous wear schedule for 30 and 7 days.
  
  
  METHODS
  Lipids from subject-worn lenses were extracted using 1:1 chloroform: methanol and transmethylated using 5% sulfuric acid in methanol. Fatty acid methyl esters (FAMEs) were collected using hexane and water, and analyzed by GCMS (Varian 3800 GC, Saturn 2000 MS).
  
  
  RESULTS
  The gas chromatograms of lens extracts that were worn on a continuous wear schedule showed two predominant peaks, C16:0 and C18:0, both of which are saturated fatty acids. This was the case for balafilcon A and lotrafilcon A lenses. However, the gas chromatograms of lens extracts that were worn on a daily wear schedule showed saturated (C16:0, C18:0) and unsaturated (C16:1 and C18:1) fatty acids.
  
  
  CONCLUSIONS
  Unsaturated fatty acids are degraded during sleep in contact lenses. Degradation occurred independently of lens material or subject-to-subject variability in lipid deposition. The consequences of lipid degradation are the production of oxidative products, which may be linked to contact lens discomfort.
authors.affiliation: Aston University, Biomaterials Research Unit, Bio-Materials and Molecular Science Group, Aston, Birmingham, United Kingdom.
authors.forename: Amandeep
authors.initials: A
authors.lastname: Panaser
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Tighe
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D003262:Contact Lenses, Extended-Wear; D005136:Eye Proteins / Q000032:analysis*; D005260:Female; D005500:Follow-Up Studies; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D008055:Lipids / Q000032:analysis*; D008297:Male; D055815:Young Adult
chemical_list: D001672:Biocompatible Materials; D005136:Eye Proteins; D008055:Lipids
keywords: contact lens discomfort; lipid degradation; overnight contact lens wear