title: Comparison of biomechanical parameters in penetrating keratoplasty and normal eyes using the Ocular Response Analyser.
abstract: BACKGROUND
  To compare corneal hysteresis (CH) and corneal resistance factor (CRF) in eyes 1 year following penetrating keratoplasty (PK) with that of normal eyes using the Ocular Response Analyser.
  
  
  METHODS
  Prospective case comparison of 166 normal right eyes and 34 unilateral post-PK eyes presenting to a teaching hospital in Birmingham, UK. The CH, CRF and Goldmann-correlated intraocular pressure, of each eye was measured using the Ocular Response Analyser. The central corneal thickness (CCT) was measured using an ultrasonic pachymeter.
  
  
  RESULTS
  The mean CH was 10.6 ± 2.0 mmHg, standard deviation (SD) and CRF was 10.2 ± 2.0 mmHg (SD) in normal eyes and 8.9 ± 3.3 mmHg and 8.1 ± 3.3 mmHg in post-PK eyes, respectively. The mean CCT was 541.8 ± 36.1 µm in normal eyes and 556.0 ± 69.2 µm in post-PK eyes. The Goldmann-correlated intraocular pressure was 16.1 ± 3.1 mmHg and 12.4 ± 2.9 mmHg in normal eyes and post-PK eyes, respectively. The CCT was found to be higher in post-PK eyes compared with normal eyes but the difference was not statistically significant (P > 0.5).
  
  
  CONCLUSIONS
  Reduced biomechanical measures were found in post-PK eyes despite a higher mean CCT. This may be due to the altered corneal structure following PK.
authors.affiliation: Heart of England Foundation Trust, Solihull, UK.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Laiquzzaman
authors.forename: Katya
authors.initials: K
authors.lastname: Tambe
authors.forename: Sunil
authors.initials: S
authors.lastname: Shah
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena / Q000502:physiology*; D003187:Compliance / Q000502:physiology*; D003315:Cornea / Q000000981:diagnostic imaging / Q000502:physiology*; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D015948:Keratoplasty, Penetrating; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014463:Ultrasonography; D055815:Young Adult