title: The effect of artificial tears on visual performance in normal subjects wearing contact lenses.
abstract: OBJECTIVE
  Disruption of the anterior refracting surface of the eye reduces visual performance. In the case of a contact lens wearer, this surface is the prelens tear film. This study determined whether artificial tears stabilize the tear film in contact lens wearers and maintained optimal visual performance for a prolonged period.
  
  
  METHODS
  Five normal subjects all in good general and ocular health and adapted to contact lens wear were fitted with Acuvue lenses. A temporal, two-alternative, forced-choice paradigm was used to measure contrast sensitivity. The stimuli were vertically oriented sine-wave gratings (between 0.5 and 14 cpd) presented for 16.67 ms. The stimuli were presented at two different times after blink detection: 2 s after blink detection (i.e., before tear layer break-up) or 4 s after tear film break-up. Three conditions were investigated at 4 s after tear layer break-up: (1) without artificial tears added, (2) with Clerz2 (Ciba Vision) instilled, and (3) with Sensitive Eyes (Bausch & Lomb) applied. The artificial tears were instilled at 10-min intervals during the experimental run.
  
  
  RESULTS
  High spatial frequency contrast sensitivity was found to be reduced after tear film break-up and was not enhanced by either tear solution.
  
  
  CONCLUSIONS
  This study indicates that there is no effect of Clerz2 or Sensitive Eyes in maintaining or improving visual performance beyond the normal prelens tear film break-up time in normal subjects wearing Acuvue lenses.
authors.affiliation: Southern California College of Optometry, 2575 Yorba Linda Blvd., Fullerton, CA 92831-1699, USA. wridder@scco.edu
authors.forename: William H
authors.initials: WH
authors.lastname: Ridder
authors.forename: Alan
authors.initials: A
authors.lastname: Tomlinson
mesh_terms: D000328:Adult; D003263:Contact Lenses, Hydrophilic; D015350:Contrast Sensitivity / Q000502:physiology*; D006801:Humans; D009883:Ophthalmic Solutions / Q000008:administration & dosage*; D013666:Tears / Q000378:metabolism; D014792:Visual Acuity / Q000502:physiology*
chemical_list: D009883:Ophthalmic Solutions