title: Clinical comparison of the Icare tonometer and Goldmann applanation tonometry.
abstract: OBJECTIVE
  To compare a new method of intraocular pressure (IOP) measurement, using the Icare tonometer, with Goldmann applanation tonometry (GAT).
  
  
  METHODS
  Two observers obtained IOP readings in 292 eyes (143 right and 149 left) of 153 subjects, using the Icare without topical anesthetic. A GAT reading was subsequently obtained by a consultant ophthalmologist, without the knowledge of the Icare readings. Central corneal thickness (CCT) was obtained on all eyes with ultrasound pachymetry. Patient comfort after IOP measurement was assessed in a consecutive subset of patients.
  
  
  RESULTS
  The intraclass correlation coefficient between the 2 modalities of IOP measurement was r=0.95 for the right and r=0.93 for the left eye. The mean difference (Icare-GAT) between the IOP measured by the 2 methods was 0.4 mm Hg in the right eye (SD 3.0, 95% confidence interval -5.5 to 6.3), and 0.8 mm Hg in the left eye (SD 3.0, confidence interval -4.7 to 6.2). GAT measurements did not vary with CCT [correlation coefficient=0.09 (P=0.25) right and 0.14 (P=0.09) left eyes]. However, IOP measured with Icare tonometry increased with increasing CCT [correlation coefficient=0.16 (P=0.05) right and 0.21 (P=0.01) left eyes]. For every 100-microm increase in CCT, the difference (Icare-GAT) increased by 1 mm Hg. Of the 38 consecutive patients surveyed, 28 (73.7%) rated the Icare more comfortable than GAT, with only 2 (5.3%) rating it less comfortable (P<0.001).
  
  
  CONCLUSIONS
  There is good correlation between the 2 methods of IOP measurement, even at extremes of IOP. The Icare instrument was easy to use and recorded rapid and consistent readings with minimal training. It seems to be more comfortable than GAT and obviates the need for topical anesthesia.
authors.affiliation: Department of Ophthalmology, Flinders Medical Centre, Bedford Park, South Australia. nima.pakrou@eyeandear.org.au
authors.forename: Nima
authors.initials: N
authors.lastname: Pakrou
authors.forename: Tim
authors.initials: T
authors.lastname: Gray
authors.forename: Richard
authors.initials: R
authors.lastname: Mills
authors.forename: John
authors.initials: J
authors.lastname: Landers
authors.forename: Jamie
authors.initials: J
authors.lastname: Craig
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005902:Glaucoma, Open-Angle / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D014065:Tonometry, Ocular / Q000379:methods* / Q000592:standards