title: Effect of artificial tears on tear stress test.
abstract: OBJECTIVE
  To determine the effect of two artificial tears of different viscosities in the relief of environmental dry eye induced with a novel tear stress test (TST).
  
  
  METHODS
  A novel TST was developed and validated. The following four test conditions were evaluated in 12 healthy normal subjects in a cross-over and subject masked study; unprotected (no test solution used), relief (test solution instilled just after application of TST), immediate protection (test solution instilled just before application of TST), and chronic protection (1 week prophylactic use of the solution). The test solutions were Cellumed, with high viscosity, and Refresh Contacts, with low viscosity. Low contrast visual acuity, symptoms with analogue scales (symptom scoring), non-invasive tear break-up time, and tear evaporation were measured before (prestress) and 2 min after (poststress) application of TST. Two weeks of washout period was allowed after first test solution.
  
  
  RESULTS
  In unprotected test condition, there was no significant difference between pre- and poststress visual acuity (p = 0.102), tear evaporation (p = 0.530), and non-invasive tear break-up time (p = 0.878), however, poststress total symptom score was significantly higher than prestress (p = 0.002). No significant differences were seen between pre- and post-total symptom score at relief (p = 0.241 for Cellumed and 0.114 for Refresh Contacts) and immediate protection (p = 0.890 for Cellumed and 0.136 for Refresh Contacts) for both test solutions, whereas postsymptoms total score was significantly higher than prestress at chronic protection (p = 0.003 for both). No significant differences were seen in the effect of the two solutions in all test conditions.
  
  
  CONCLUSIONS
  There is an increase in dry eye symptomatology after ocular stress. The use of artificial tears just before or after ocular stress is helpful in relieving resultant symptoms in normals.
authors.affiliation: Department of Vision Sciences, Glasgow Caledonian University, 70 Cowcaddens Road, Glasgow, United Kingdom. s.khanal@uws.edu.au
authors.forename: Santosh
authors.initials: S
authors.lastname: Khanal
authors.forename: Peter A
authors.initials: PA
authors.lastname: Simmons
authors.forename: Edward I
authors.initials: EI
authors.lastname: Pearce
authors.forename: Mhairi
authors.initials: M
authors.lastname: Day
authors.forename: Alan
authors.initials: A
authors.lastname: Tomlinson
mesh_terms: D000328:Adult; D001273:Atmosphere Exposure Chambers; D001767:Blinking / Q000502:physiology; D016288:Computer Terminals; D015350:Contrast Sensitivity / Q000502:physiology; D018592:Cross-Over Studies; D003941:Diagnostic Techniques, Ophthalmological; D004311:Double-Blind Method; D015352:Dry Eye Syndromes / Q000188:drug therapy* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008954:Models, Biological; D009883:Ophthalmic Solutions / Q000008:administration & dosage*; D010865:Pilot Projects; D013666:Tears / Q000737:chemistry / Q000502:physiology; D016896:Treatment Outcome; D014783:Viscosity; D014792:Visual Acuity / Q000502:physiology
chemical_list: D009883:Ophthalmic Solutions