title: Clinical and biochemical tear lipid parameters in contact lens wearers.
abstract: OBJECTIVE
  Alterations in tear film lipids may be important in modulating discomfort during contact lens wear. This study investigates associations between clinical and biological components of the lipid layer and seeks to determine the effect of lipid supplementation on contact lens wear comfort.
  
  
  METHODS
  Participants were grouped into symptomatic (n = 10) and asymptomatic (n = 10) contact lens wearers according to the Contact Lens Dry Eye Questionnaire. After 6 hours of lens wear, noninvasive surface drying time (NISDT) and the lipid layer grade were assessed using a Tearscope. Basal tears were collected using a microcapillary tube and assayed for concentration and activity of the secretory phospholipase A2 enzyme and concentration of the lipid aldehyde malondialdehyde. Mass spectrometry was used to characterize the tear lipidome. In the second phase, a liposomal spray (Tears Again, BioRevive) or a saline spray was sprayed over the upper eyelids of each subject during their down gaze and during lens wear. Noninvasive surface drying time and ocular comfort were obtained soon after spraying and again at 2 and 6 hours after the initial spray. Statistical tests included the Student t test, repeated-measures analysis of variance, and the Pearson correlation test where appropriate.
  
  
  RESULTS
  Noninvasive surface drying time was lower (p = 0.01) in symptomatic (4.5 ± 0.6 seconds) than in asymptomatic (9.9 ± 3.1 seconds) contact lens wearers. The mole percentage of wax esters in the total lipidome increased with NISDT (R = 0.70, p = 0.01). Secretory phospholipase A2 enzyme activity in tears was associated with higher levels of malondialdehyde (R = 0.65, p = 0.01) and shorter NISDT (R = 0.84, p = 0.001). Noninvasive surface drying time reduced over the time course for the saline spray (p = 0.01) but did not reduce until the 6-hour time point with the liposomal spray. With liposomal spray, NISDT was higher (p = 0.03) immediately after instillation compared with 6 hours later (9.5 ± 1.9 vs. 5.2 ± 2.1 seconds). A longer NISDT was associated with improved ocular comfort for those using the liposomal spray (R = 0.25, p = 0.005) but not with saline.
  
  
  CONCLUSIONS
  Degraded lipids and a lower mole percentage of wax esters in the tear film may be associated with a lower NISDT. Lipid supplements may improve ocular comfort during lens wear by increasing NISDT.
authors.affiliation: *BS †PhD, FAAO ‡PhD School of Optometry and Vision Science, the University of New South Wales, Sydney, New South Wales, Australia (AR, FS); Brien Holden Vision Institute, Sydney, New South Wales, Australia (AR, MDPW, FS); and School of Medicine, and School of Health Sciences, the University of Wollongong, Wollongong, New South Wales, Australia (SHJB, TWM).
authors.forename: Athira
authors.initials: A
authors.lastname: Rohit
authors.forename: Mark D P
authors.initials: MD
authors.lastname: Willcox
authors.forename: Simon H J
authors.initials: SH
authors.lastname: Brown
authors.forename: Todd W
authors.initials: TW
authors.lastname: Mitchell
authors.forename: Fiona
authors.initials: F
authors.lastname: Stapleton
mesh_terms: D000328:Adult; D003263:Contact Lenses, Hydrophilic; D005260:Female; D006801:Humans; D008055:Lipids / Q000032:analysis*; D065346:Lubricant Eye Drops / Q000008:administration & dosage; D008297:Male; D008315:Malondialdehyde / Q000032:analysis*; D013058:Mass Spectrometry; D054497:Phospholipases A2, Secretory / Q000032:analysis*; D011795:Surveys and Questionnaires; D013666:Tears / Q000737:chemistry*; D055815:Young Adult
chemical_list: D008055:Lipids; D065346:Lubricant Eye Drops; D008315:Malondialdehyde; D054497:Phospholipases A2, Secretory