Intraocular pressure measurements and corneal biomechanical properties using a dynamic Scheimpflug analyzer, after several keratoplasty techniques, versus normal eyes

J Fr Ophtalmol. 2018 Jan;41(1):30-38. doi: 10.1016/j.jfo.2017.06.006. Epub 2017 Nov 28.

Abstract

Purpose: To evaluate the biomechanical properties of the cornea and their impact on intraocular pressure (IOP) measurement after lamellar keratoplasty, compared to healthy eyes, using a non-contact tonometer with a Scheimpflug camera.

Methods: This study, from 2014 to 2015, included 22 primary DSAEK, 5 DALK, 6 DSAEK after PK, and 50 control eyes. Using a non-contact tonometer with a high-speed Scheimpflug camera (CORVIS ST, Oculus Optikgeräte GmbH, Wetzlar, Germany), several biomechanical parameters were recorded, including radius at highest concavity (Rhc) and defomation amplitude (DA). Central corneal thickness (CCT) and uncorrected IOP, were also recorded. For the control eyes only, a corrected IOP was calculated, based on age, central corneal thickness, and biomechanical parameters.

Results: Rhc was significantly lower after DALK (Rhc=5.54±0.71, P=0.007) and DSAEK (Rhc=6.26±0.77, P=0.042) compared to control eyes (Rhc=6.82±0.76). DA was higher after DALK and DSAEK, but not significantly (respectively 1.24±0.09 P=0.41 and 1.22±0.15, P=0.923) compared to normal eyes (1.18±0.15). Uncorrected IOP was not significantly different between post-keratoplasty and control eyes. In control eyes, the corrected IOP (15.23±1.88) was lower than the uncorrected IOP (16.10±2.34); a statistically significant positive correlation between Rhc and CCT (R2=0.6020, P<0001), and a significant negative correlation between DA and CCT (R2=-0.641, P<0.0001) were found.

Conclusion: Our study showed that, after lamellar keratoplasty, corneal biomechanics are altered. Corneas with higher ocular rigidity will show a lower DA and a higher Rhc.

Keywords: Biomécanique cornéenne; Corneal biomechanics; Intraocular pressure; Keratoplasty; Kératoplastie; Pression intraoculaire; Scheimpflug; Scheimpflug technology.

MeSH terms

  • Adult
  • Aged
  • Biomechanical Phenomena
  • Case-Control Studies
  • Cornea / cytology
  • Cornea / diagnostic imaging*
  • Cornea / physiology*
  • Corneal Diseases / diagnosis
  • Corneal Diseases / therapy
  • Corneal Transplantation / methods
  • Corneal Transplantation / rehabilitation*
  • Diagnostic Techniques, Ophthalmological / instrumentation
  • Female
  • Healthy Volunteers
  • Humans
  • Intraocular Pressure* / physiology
  • Male
  • Middle Aged
  • Postoperative Period
  • Tonometry, Ocular / instrumentation
  • Tonometry, Ocular / methods
  • Video Recording / instrumentation
  • Video Recording / methods