title: Central corneal thickness and corneal hysteresis associated with glaucoma damage.
abstract: OBJECTIVE
  We sought to measure the impact of central corneal thickness (CCT), a possible risk factor for glaucoma damage, and corneal hysteresis, a proposed measure of corneal resistance to deformation, on various indicators of glaucoma damage.
  
  
  METHODS
  Observational study.
  
  
  METHODS
  Adult patients of the Wilmer Glaucoma Service underwent measurement of hysteresis on the Reichert Ocular Response Analyzer and measurement of CCT by ultrasonic pachymetry. Two glaucoma specialists (H.A.Q., N.G.C.) reviewed the chart to determine highest known intraocular pressure (IOP), target IOP, diagnosis, years with glaucoma, cup-to-disk ratio (CDR), mean defect (MD), pattern standard deviation (PSD), glaucoma hemifield test (GHT), and presence or absence of visual field progression.
  
  
  RESULTS
  Among 230 subjects, the mean age was 65 +/- 14 years, 127 (55%) were female, 161 (70%) were white, and 194 (85%) had a diagnosis of primary open-angle glaucoma (POAG) or suspected POAG. In multivariate generalized estimating equation models, lower corneal hysteresis value (P = .03), but not CCT, was associated with visual field progression. When axial length was included in the model, hysteresis was not a significant risk factor (P = .09). A thinner CCT (P = .02), but not hysteresis, was associated with a higher CDR at the most recent examination. Neither CCT nor hysteresis was associated with MD, PSD, or GHT "outside normal limits."
  
  
  CONCLUSIONS
  Thinner CCT was associated with the state of glaucoma damage as indicated by CDR. Axial length and corneal hysteresis were associated with progressive field worsening.
authors.affiliation: Wilmer Eye Institute, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Baltimore, MD 21287, USA. ncongdon@jhmi.edu
authors.forename: Nathan G
authors.initials: NG
authors.lastname: Congdon
authors.forename: Aimee T
authors.initials: AT
authors.lastname: Broman
authors.forename: Karen
authors.initials: K
authors.lastname: Bandeen-Roche
authors.forename: Davinder
authors.initials: D
authors.lastname: Grover
authors.forename: Harry A
authors.initials: HA
authors.lastname: Quigley
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D001837:Body Weights and Measures; D003315:Cornea / Q000033:anatomy & histology* / Q000502:physiology*; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000175:diagnosis; D012307:Risk Factors; D014065:Tonometry, Ocular; D014786:Vision Disorders / Q000175:diagnosis; D014794:Visual Fields