title: Corneal biomechanics measured with the ocular response analyser in patients with unilateral open-angle glaucoma.
abstract: OBJECTIVE
  To evaluate the relationship between biomechanical properties of the cornea and intraocular pressure (IOP) and the role of biomechanical properties in eyes of patients with unilateral primary open-angle glaucoma (POAG).
  
  
  METHODS
  The biomechanical properties of corneal hysteresis (CH) and the corneal resistance factor (CRF) were measured with the ocular response analyser (ORA). In an experimental setting, three human donor eyes with Schiotz-tonometry-controlled IOP were investigated. In addition, a series of patients with unilateral POAG were evaluated. Main outcome measures were CH, CRF, corneal-compensated IOP (IOPcc), standard automated perimetry parameters mean defect (MD) and pattern standard deviation, central corneal thickness, Goldmann applanation tonometry (GAT), and cup-to-disc ratio.
  
  
  RESULTS
  A highly significant linear correlation between CH and the corneal-compensated IOP (IOPcc, r = -0.926; p < 0.001) was found. The correlation between IOP(CC) and CRF was not significant (r = 0.335; p = 0.08). In total, 36 eyes of 18 patients with unilateral POAG were examined. Regarding uncorrected CH (mean 7.73 ± 1.46 mmHg glaucomatous eye and 9.28 ± 1.42 mmHg fellow eye), there was a highly significant difference between both eyes. This difference disappears, when CH was corrected for IOP (9.44 ± 3.78 mmHg and 9.97 ± 3.22 mmHg, respectively).
  
  
  CONCLUSIONS
  Corneal hysteresis but not corneal resistance factor is dependent on IOP. In patients with unilateral POAG, IOP is higher in the affected eye. When CH is corrected for IOP, corneal biomechanical properties do not differ in both eyes of patients with unilateral POAG.
authors.affiliation: Department of Ophthalmology, Ludwig-Maximilians University, Klinikum der Universität Muenchen, Campus Innenstadt, Munich, Germany. Christoph.Hirneiss@med.uni-muenchen.de
authors.forename: Christoph
authors.initials: C
authors.lastname: Hirneiss
authors.forename: Aljoscha S
authors.initials: AS
authors.lastname: Neubauer
authors.forename: Alice
authors.initials: A
authors.lastname: Yu
authors.forename: Anselm
authors.initials: A
authors.lastname: Kampik
authors.forename: Marcus
authors.initials: M
authors.lastname: Kernt
mesh_terms: D001696:Biomechanical Phenomena / Q000502:physiology*; D003315:Cornea / Q000502:physiology*; D004548:Elasticity / Q000502:physiology*; D054459:Elasticity Imaging Techniques; D005260:Female; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D014019:Tissue Donors; D014065:Tonometry, Ocular; D058609:Visual Field Tests; D014794:Visual Fields