title: [The measured value of corneal hysteresis and resistance factor with their related factors analysis in normal eyes].
abstract: OBJECTIVE
  The aim of this study was to investigate the corneal hysteresis (CH) and corneal resistance factor (CRF) in normal eyes and to determine their relationship between central corneal thickness (CCT), corneal curvature, sphere equivalence (SE) and intraocular pressure (IOP).
  
  
  METHODS
  Cross-sectional study. This study included 205 normal eyes (205 patients). Ocular Response Analyzer (ORA, Reichert Ophthalmic Instruments, New York, USA) was used to measure CH and CRF. Multivariate regression analysis was applied to study their relationship between CCT, corneal curvature, SE, IOP (noncontact tonometer).
  
  
  RESULTS
  The values of CH and CRF in 205 eyes presented normal distribution and concentrated on 8.1 to 11.0 mm Hg (1 mm Hg = 0.133 kPa). No statistical significant difference was found in both CH and CRF of different gender and ages (< 25 years or > or = 25 years) (P > 0.05). 95% reference interval of CH and CRF in 205 eyes were 6.8 to 13.0 mm Hg and 6.6 to 13.6 mm Hg. The correlation of CH and CRF with CCT, corneal curvature, SE and IOP were significant (P < 0.05).
  
  
  CONCLUSIONS
  CH and CRF measure different biomechanical aspects of cornea, they may reflect the combined effect of CCT, corneal curvature, rigidity, hydration and IOP. These values of CH and CRF in normal eyes established foundation to further investigate their relationship with eye diseases.
authors.affiliation: Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai 200031, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Liu
authors.forename: Ren-yuan
authors.initials: RY
authors.lastname: Chu
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.forename: Xing-tao
authors.initials: XT
authors.lastname: Zhou
mesh_terms: D000293:Adolescent; D000328:Adult; D000886:Anthropometry; D001696:Biomechanical Phenomena; D003315:Cornea / Q000033:anatomy & histology* / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055815:Young Adult