title: Evaluation of Corneal Biomechanical Properties in Patients With Thyroid Eye Disease Using Ocular Response Analyzer.
abstract: OBJECTIVE
  To assess variations in the corneal biomechanical properties in thyroid eye disease (TED) patients using ocular response analyzer (ORA).
  
  
  METHODS
  In this observational cross-sectional study, 75 patients with TED and 57 healthy subjects were enrolled. The mean age of the patients and healthy subjects were 47.50±1.55 and 43.6±1.23 years, respectively (P=0.06). All study participants underwent comprehensive ophthalmologic examination, Goldmann applanation tonometry (GAT), corneal pachymetry, and corneal biomechanical analysis using ORA. Corneal hysteresis (CH), corneal resistance factor (CRF), cornea-compensated IOP value (IOPcc), and Goldmann-corrected IOP value (IOPg) were measured with ORA.
  
  
  RESULTS
  Central corneal thickness (CCT) in patients group (536.18±36.20 μm) and control group (539.22±28.83 μm) were not significantly different (P=0.1). In TED group, the IOPcc (20.23±0.54 mm Hg) was significantly higher than both IOP-GAT (17.54±0.49 mm Hg, P<0.001) and IOPg (18.35±0.52, P<0.001). CH in TED patients (9.01±0.20) was significantly lower compared with CH in healthy subjects (10.45±0.21) (P<0.001). Although CRF was lower in TED patients (10.06±0.16) in comparison with normal subjects (10.42±0.29), this difference was not statistically significant (P=0.25). Both CH and CRF were positively correlated with CCT (r=0.52, P<0.001 and r=0.62, P<0.001, respectively) in TED group.
  
  
  CONCLUSIONS
  In TED patients, CH seems to be lower than in normal subjects. GAT might underestimate the IOP due to differences in corneal properties of cornea in TED patients.
authors.affiliation: *Eye Research Center (ERC), Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran †Department of Ophthalmology, Jules Stein Eye Institute, UCLA, Los Angeles, CA.
authors.forename: Sasan
authors.initials: S
authors.lastname: Moghimi
authors.forename: Mona
authors.initials: M
authors.lastname: Safizadeh
authors.forename: Mehdi
authors.initials: M
authors.lastname: Mazloumi
authors.forename: Hamid
authors.initials: H
authors.lastname: Hosseini
authors.forename: Zakieh
authors.initials: Z
authors.lastname: Vahedian
authors.forename: Mohammad T
authors.initials: MT
authors.lastname: Rajabi
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D003315:Cornea / Q000503:physiopathology*; D063171:Corneal Pachymetry; D003430:Cross-Sectional Studies; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation; D004548:Elasticity / Q000502:physiology*; D005260:Female; D049970:Graves Ophthalmopathy / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D014065:Tonometry, Ocular; D014794:Visual Fields