title: Graft biomechanical properties after penetrating keratoplasty versus deep anterior lamellar keratoplasty.
abstract: OBJECTIVE
  To compare biomechanical properties of transplanted corneas after penetrating keratoplasty (PK) with those after deep anterior lamellar keratoplasty (DALK) using Anwar's big-bubble technique.
  
  
  METHODS
  This cross-sectional comparative study consisted of 45 PK eyes (group 1) and 23 DALK eyes (group 2) with the underlying pathology of keratoconus. The Ocular Response Analyzer was used to measure Goldmann-correlated intraocular pressure (IOPg) and cornea-compensated IOP (IOPcc), as well as graft biomechanical properties, namely corneal hysteresis (CH) and corneal resistance factor (CRF). The results were compared between the study groups using independent t-test.
  
  
  RESULTS
  Mean patient age was 29.8 ± 6.1 years in group 1 and 27.2 ± 6.5 years in group 2 (P = 0.11) and they were followed up for 31.4 ± 19.0 months and 29.2 ± 17.3 months after corneal transplantation, respectively (P = 0.27). There was no significant difference between the study groups in terms of recipient (P = 0.21) and donor (P = 0.57) trephine sizes or BSCVA (P = 0.77). CH was measured 10.09 ± 2.5 mmHg in group 1 and 9.64 ± 2.1 mmHg in group 2 (P = 0.36). CRF was 10.13 ± 2.2 and 9.36 ± 2.1 mmHg, respectively (P = 0.17). Similarly, no significant difference was found between group 1 and group 2 in terms of IOPg (P = 0.25) and IOPcc (P = 0.80).
  
  
  CONCLUSIONS
  DALK using the big-bubble technique for keratoconic eyes provides corneal biomechanics comparable to PK.
authors.affiliation: Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Jafarinasab
authors.forename: Sepehr
authors.initials: S
authors.lastname: Feizi
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Javadi
authors.forename: Ali
authors.initials: A
authors.lastname: Hashemloo
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology*; D003315:Cornea / Q000502:physiology*; D016039:Corneal Transplantation; D003430:Cross-Sectional Studies; D004547:Elastic Tissue / Q000502:physiology; D004548:Elasticity; D005500:Follow-Up Studies; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D007640:Keratoconus / Q000503:physiopathology / Q000601:surgery*; D015948:Keratoplasty, Penetrating