title: Atomic force microscopy and Langmuir-Blodgett monolayer technique to assess contact lens deposits and human meibum extracts.
abstract: OBJECTIVE
  The purpose of this exploratory study was to investigate the differences in meibomian gland secretions, contact lens (CL) lipid extracts, and CL surface topography between participants with and without meibomian gland dysfunction (MGD).
  
  
  METHODS
  Meibum study: Meibum was collected from all participants and studied via Langmuir-Blodgett (LB) deposition with subsequent Atomic Force Microscopy (AFM) visualization and surface roughness analysis. CL Study: Participants with and without MGD wore both etafilcon A and balafilcon A CLs in two different phases. CL lipid deposits were extracted and analyzed using pressure-area isotherms with the LB trough and CL surface topographies and roughness values were visualized using AFM.
  
  
  RESULTS
  Meibum study: Non-MGD participant meibum samples showed larger, circular aggregates with lower surface roughness, whereas meibum samples from participants with MGD showed more lipid aggregates, greater size variability and higher surface roughness. CL Study: Worn CLs from participants with MGD had a few large tear film deposits with lower surface roughness, whereas non-MGD participant-worn lenses had many small lens deposits with higher surface roughness. Balafilcon A pore depths were shallower in MGD participant worn lenses when compared to non-MGD participant lenses. Isotherms of CL lipid extracts from MGD and non-MGD participants showed a seamless rise in surface pressure as area decreased; however, extracts from the two different lens materials produced different isotherms.
  
  
  CONCLUSIONS
  MGD and non-MGD participant-worn CL deposition were found to differ in type, amount, and pattern of lens deposits. Lipids from MGD participants deposited irregularly whereas lipids from non-MGD participants showed more uniformity.
authors.affiliation: School of Optometry and Vision Science, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1.
authors.forename: Sarah
authors.initials: S
authors.lastname: Hagedorn
authors.affiliation: Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1; Waterloo Institute of Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Drolle
authors.affiliation: School of Optometry and Vision Science, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1; Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L8.
authors.forename: Holly
authors.initials: H
authors.lastname: Lorentz
authors.affiliation: School of Optometry and Vision Science, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1. Electronic address: s2srinivasan@uwaterloo.ca.
authors.forename: Sruthi
authors.initials: S
authors.lastname: Srinivasan
authors.affiliation: Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1; Waterloo Institute of Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1; Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1.
authors.forename: Zoya
authors.initials: Z
authors.lastname: Leonenko
authors.affiliation: School of Optometry and Vision Science, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1; Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1; Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3G1.
authors.forename: Lyndon
authors.initials: L
authors.lastname: Jones
mesh_terms: D000328:Adult; D000368:Aged; D003263:Contact Lenses, Hydrophilic / Q000009:adverse effects*; D015352:Dry Eye Syndromes / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008537:Meibomian Glands / Q000378:metabolism*; D018625:Microscopy, Atomic Force / Q000379:methods*; D008875:Middle Aged; D012629:Sebum / Q000737:chemistry*; D013499:Surface Properties; D013666:Tears / Q000378:metabolism
keywords: Atomic force microscopy (AFM); Contact lens deposits; Depósitos de las lentes de contacto; Disfunción de las glándulas de Meibomio (MGD); Langmuir–Blodgett; Meibomian gland dysfunction (MGD); Meibum; Microscopio de fuerza atómica (AFM); Secreciones de las glándulas de Meibomio