Cornea

Accuracy of an Air-Puff Dynamic Tonometry Biomarker to Discriminate the Corneal Biomechanical Response in Patients With Keratoconus

imagePurpose:

The aim of this study was to assess accuracy of the mean corneal stiffness (kc, N/m) parameter to discriminate between patients with keratoconus and age-matched healthy subjects.

Methods:

Dynamic Scheimpflug imaging tonometry was performed with Corvis ST (Oculus Optikgeräte GmbH, Germany) in patients with keratoconus (n = 24; study group) and age-matched healthy subjects (n = 32; control). An image processing algorithm was developed to analyze the video sequence of the Corvis ST air-puff event and to determine the geometric and temporal parameters that correlated with the corneal tissue biomechanical properties. A modified 3-element viscoelastic model was used to derive the kc parameter, which represented the corneal tissue resistance to deformation under load. Receiver operating characteristic curves were used to assess the overall diagnostic performance for determining the area under the curve, sensitivity, and specificity of the kc in assessing the corneal tissue deformation to the Corvis ST air-puff event in keratoconus and control eyes. The Corvis Biomechanical Index (CBI) was analyzed for external validation.

Results:

The kc parameter was significantly different between keratoconus and controls (P

By , ago

Impact of Previous Cataract Surgery in Corneal Donors on the Outcome of Descemet Membrane Endothelial Keratoplasty

imagePurpose:

The aim of this study was to investigate differences between phakic, pseudophakic, and scarred stromal donor tissue for their influence on complication rates during preparation or implantation and on the postoperative outcome of Descemet membrane endothelial keratoplasty (DMEK).

Methods:

We retrospectively compared 484 eyes undergoing DMEK, divided into 3 subgroups of donor tissue (1: phakic, 2: pseudophakic, and 3: scarred stromal). Visual acuity, central corneal thickness (CCT), and endothelial cell count were monitored preoperatively and postoperatively at 6 weeks and 3, 6, 12, and 24 months. The incidence of intraoperative and postoperative complications was analyzed.

Results:

The risk of adherence and tearing during preparation was significantly higher in group 2 than in the other groups (p’s

By , ago