title: [Changes in corneal topography after using tear substitutes].
abstract: BACKGROUND
  Computer-controlled video keratoscopy is being employed ever more frequently and for various indications.
  
  
  METHODS
  We have studied the effects of high-viscosity and low-viscosity tear substitutes on the corneal topography, one and five minutes after application to 14 normal eyes of 7 subjects, and compared the results.
  
  
  RESULTS
  In contrast to low-viscosity preparations, high-viscosity preparations cause an appreciable increase in astigmatism and an alteration of the axis shortly after application. The variations caused by low-viscosity tear substitutes lie within the normal range of variation between several measurements.
  
  
  CONCLUSIONS
  At least in the case of the normal eye, gels should not be applied immediately before keratometry. In the case of patients who have undergone keratoplasty, however, it can be helpful before fitting contact lenses. In addition keratometry can be helpful to determine the residence time of ophthalmic preparations being different in viscosity.
authors.affiliation: Augenklinik der Medizinischen Hochschule Hannover.
authors.forename: C W
authors.initials: CW
authors.lastname: Emde
authors.forename: H
authors.initials: H
authors.lastname: Brewitt
authors.forename: R
authors.initials: R
authors.lastname: Winter
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000175:diagnosis; D003315:Cornea / Q000187:drug effects* / Q000473:pathology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009883:Ophthalmic Solutions / Q000008:administration & dosage / Q000009:adverse effects*; D019721:Ophthalmoscopes; D012016:Reference Values; D012029:Refraction, Ocular; D014741:Video Recording / Q000295:instrumentation*; D014783:Viscosity
chemical_list: D009883:Ophthalmic Solutions
vernacular_title: Veränderungen der Hornhaut-Topographien nach Anwendung von Tränenersatzmitteln.