title: Comparison of iCare tonometer and Goldmann applanation tonometry in normal corneas and in eyes with automated lamellar and penetrating keratoplasty.
abstract: OBJECTIVE
  To compare intraocular pressure (IOP) measurements with Goldmann applanation tonometry (GAT) and iCare tonometry in normal and post-keratoplasty corneas and to assess the influence of central corneal thickness (CCT), corneal curvature (CC), and corneal astigmatism (CA) on IOP.
  
  
  METHODS
  This prospective cross-sectional study included one eye of 101 subjects with normal corneas (58 healthy subjects, 43 glaucoma); and 90 post-keratoplasty patients: 34 penetrating keratoplasties (PK); 20 automated-lamellar-therapeutic keratoplasties (ALTK); 19 Descemet-stripping-automated-endothelial keratoplasties (DSAEK); 17 edematous grafts. All subjects underwent GAT and iCare IOP measurements in random order, and CCT, CC, and CA evaluation. The Bland-Altman method and multivariate regression analysis were used to assess inter-tonometer agreement and the influence of CCT, CC, and CA on IOP.
  
  
  RESULTS
  iCare significantly underestimated IOP in all groups compared with GAT (GAT minus iCare of 3.5±3.5 mm Hg, P<0.001), but overestimated IOP in the edematous grafts (GAT minus iCare of -6.5±1.9 mm Hg, P<0.001). In normal corneas, both tonometer measurements were directly related to CCT values; iCare readings appeared inversely related to CC. There was no significant relationship between IOP and CCT, CC and CA in post-keratoplasty eyes, except between CC and iCare measurements for PK eyes.
  
  
  CONCLUSIONS
  The agreement between GAT and iCare was clinically acceptable in control, ALTK and DSAEK groups, and poor in PK and edematous grafts eyes. In normal corneas, GAT was significantly affected by CCT; iCare was influenced by CCT and CC. The iCare appeared less influenced by corneal edema when compared with GAT. High IOP readings taken with both tonometers in grafts should raise suspicion of true elevated IOP.
authors: Department of Ophthalmology, Azienda Ospedaliero-Universitaria Santa Maria della Misericordia, S.O.C. Oculistica, piazzale S. Maria della Misericordia 15, Udine, Italy.
authors: M L
authors: ML
authors: Salvetat
authors: M
authors: M
authors: Zeppieri
authors: F
authors: F
authors: Miani
authors: C
authors: C
authors: Tosoni
authors: L
authors: L
authors: Parisi
authors: P
authors: P
authors: Brusini
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000175:diagnosis / Q000503:physiopathology; D003315:Cornea / Q000033:anatomy & histology / Q000473:pathology; D003316:Corneal Diseases / Q000175:diagnosis* / Q000601:surgery*; D016039:Corneal Transplantation; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D015948:Keratoplasty, Penetrating; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000175:diagnosis; D011182:Postoperative Care; D011446:Prospective Studies; D014065:Tonometry, Ocular / Q000379:methods* / Q000592:standards