title: [Impression and applanation tonometry in irregular corneas. Comparison with intraocular needle tonometry].
abstract: OBJECTIVE
  During the past 4 years we have demonstrated in eyes with corneal pathology that applanation tonometry (Goldmann, Perkins) generally delivers falsely low measurements in comparison to intraocular needle tonometry. The aim of this study was to evaluate whether impression tonometry (Schioetz) is more precise than applanation tonometry in determining the intraocular pressure in eyes with corneal disorders.
  
  
  METHODS
  In 75 eyes with suspected glaucoma and various corneal disorders, we performed applanation tonometry and impression tonometry before intraocular needle tonometry. Applanation tonometry was repeated after impression tonometry to unveil a possible tonography effect. Intraocular needle tonometry was performed thereafter.
  
  
  RESULTS
  Applanation tonometry results were 4.1 +/- 5.3 mmHg below intraocular pressure as determined by intraocular needle tonometry. Impression tonometry results were also lower: 4.3 +/- 6.8 mmHg (5.5 g), 4.3 +/- 6.4 mmHg (7.5 g), and 4.8 +/- 7.0 mmHg (10.0 g). The differences between applanation tonometry and impression tonometry were statistically not significant. In contrast, all the differences between extraocular tonometry procedures and intraocular needle tonometry were statistically highly significant (P < 0.001).
  
  
  CONCLUSIONS
  In corneal pathology both, applanation tonometry and impression tonometry do not deliver reliable results on an average. Only intraocular needle-tonometry delivers reliable results in these eyes.
authors.affiliation: Universitäts-Augenklinik Düsseldorf.
authors.forename: F
authors.initials: F
authors.lastname: Madjlessi
authors.forename: W
authors.initials: W
authors.lastname: Marx
authors.forename: T
authors.initials: T
authors.lastname: Reinhard
authors.forename: C
authors.initials: C
authors.lastname: Althaus
authors.forename: R
authors.initials: R
authors.lastname: Sundmacher
mesh_terms: D003316:Corneal Diseases / Q000150:complications / Q000175:diagnosis*; D005901:Glaucoma / Q000150:complications / Q000175:diagnosis*; D006801:Humans; D011446:Prospective Studies; D014065:Tonometry, Ocular / Q000379:methods*