title: Measuring intraocular pressure after intrastromal corneal ring segment implantation with rebound tonometry and Goldmann applanation tonometry.
abstract: OBJECTIVE
  The aim of this study was to compare intraocular pressure (IOP) measurements in patients with ectatic corneas after intrastromal corneal ring segment (ICRS) implantation using the Rebound tonometers (RBTs) Icare and Icare Pro, compared with Goldmann applanation tonometry (GAT) 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 consecutively included 60 eyes of 60 patients with corneal ectasia having ICRS for at least 6 months from January 2011 to December 2013. All subjects underwent GAT, Icare, and Icare Pro IOP measurements in a random order, and CCT, CC, and CA evaluation using a Pentacam. The Bland-Altman method and multivariate regression analysis logistic method were used to assess intertonometer agreement and the influence of corneal variables on IOP measurements.
  
  
  RESULTS
  Icare significantly underestimated IOP compared with GAT [GAT - Icare 1.2 ± 3.0 mm Hg, P = 0.002 (95% confidence interval, 0.5-2.0)], whereas Icare Pro showed no statistical differences compared with GAT [GAT - Icare Pro 0.1 ± 3.1 mm Hg, P = 0.853 (95% confidence interval, -0.7 to 0.9)]. Both RBTs presented good concordance with GAT (intraclass coefficient correlation > 0.6). All tonometer measurements were influenced by CCT values and age (P < 0.05); the number of ICRS implanted did not influenced IOP measurement with any of the 3 tonometers.
  
  
  CONCLUSIONS
  Both RBTs could be an alternative to GAT in patients with corneal ectasia and ICRS; however, Icare Pro shows greater accuracy.
authors.affiliation: *Department of Ophthalmology, Hospital Clinico San Carlos, Institute of Health Care Research of the Hospital Clinico San Carlos (IdISSC), University Complutense of Madrid, Madrid, Spain; and †Unit of Clinical Methodology and Epidemiology, and Preventive Medicine, Institute of Health Care Research of the Hospital Clinico San Carlos (IdISSC), Faculty of Nursing, Podology and Physiotherapy, University Complutense of Madrid, Madrid, Spain.
authors.forename: Paula
authors.initials: P
authors.lastname: Arribas-Pardo
authors.forename: Carmen
authors.initials: C
authors.lastname: Mendez-Hernandez
authors.forename: Ricardo
authors.initials: R
authors.lastname: Cuiña-Sardiña
authors.forename: Cristina
authors.initials: C
authors.lastname: Fernandez-Perez
authors.forename: David
authors.initials: D
authors.lastname: Diaz-Valle
authors.forename: Julian
authors.initials: J
authors.lastname: Garcia-Feijoo
mesh_terms: D000328:Adult; D003319:Corneal Stroma / Q000601:surgery*; D019781:Corneal Topography; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D007640:Keratoconus / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D013508:Ophthalmologic Surgical Procedures; D011446:Prospective Studies; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D014065:Tonometry, Ocular / Q000295:instrumentation*