Descemet membrane endothelial keratoplasty and corneal biomechanics

To study the behaviour of the biomechanical properties of the cornea in DMEK (Descemet membrane endothelial keratoplasty).

Prospective longitudinal observational study. 21 pre and post-DMEK eyes. 3-month follow-up with the dynamic Scheimpflug Analyzer (Corvis ST, Oculus; Wetzlar, Germany). The following parameters were measured: IOPnc: non-corrected intraocular pressure (IOP), IOPb: IOP corrected by biomechanics, maximum deflection amplitude (DefA), CCT: central corneal pachymetry, flattening speed 1 and 2, peak distance, HC deformation amplitude: deformation amplitude in maximum concavity, integrated inverse concave radius, DAR 1 and 2: deformation amplitude at 1mm and 2mm from the corneal apex, respectively. ARTh: Ambrosial pachymetric ratio, SP1: stiffness parameter, CBI: Corvis Biomechanical index and the maximum inverse radius. Pre-operative and post-operative measurements were performed with a 3-month follow-up and compared with a paired sample t-test.

There was a significant decrease in the IOPnc of 1.54±3mmHg (p<0.05), a significant increase in the post-surgical IOPb of 3.79±3.18mmHg (p<0.001), a significant pachymetric decrease of 164.4±91.35μm (p<0.001) after the intervention. All dynamic parameters of the Scheimpflug analyzer changed significantly after surgery (p<0.05), except the ARTh and IWC variables.

Variables indicate a decrease in corneal strength post-DMEK, with an increase in IOPb, at least the first 3 months after surgery. This finding is especially relevant in the follow-up of patients with coexisting glaucoma.