Abstract
Purpose: :
When performing ultra-thin Descemet Stripping Automated Endothelial Keratoplasty (UT-DSAEK), the quality of the stromal interface and stromal thickness seem to be critical for visual outcomes. Aim of this study was to investigate whether additional osmotic deswelling prior to UT-DSAEK improves the quality of the cut-surface and leads to a more reliable and deeper cut in UT-DSAEK ("OSMO-UT-DSAEK").
Methods: :
Ten human donor corneas not suitable for transplantation were placed in an artificial anterior chamber system (Moria). A double path cutting procedure using a microkeratome (Moria) was performed on 10 corneas. After normal deswelling, 5 corneas were randomly assigned to be additionally deswollen within Thin-C Medium (Alchimia) and 5 corneas were placed in normal Culture Medium II (Biochrom), both groups for four hours. Corneal thickness was measured by ultrasound biomicroscopy (UBM) before and after deswelling, as well as after each cutting procedure and later histologically. Stromal interfaces of the grafts were classified by standardized blinded grading of the cut surface in paraffin histology.
Results: :
The grading of stromal interface smoothness significantly improved after preconditioning in Thin-C (0 smooth, 2 almost smooth, 3 rough, 0 "saw tooth" pattern) when compared to preconditioning in Medium II (1 rough, 4 "saw tooth") (p0.05, mean Difference 183, 95% CI [-8;+255]). The reference thickness in histological analysis, after the first cut with the microkeratome, showed significant correlation with the actual decrease of the cornea measured with UBM (Pearson r=0.9, P<0.005, 95% CI [-61;+57]). In contrast there was no significant correlation found between the adjusted thickness of the microkeratome and the actual thickness of the cut measured in histological analysis in both medium as well as for the first and second cut (first cut: Pearson r=0.37, P=0.29, 95% CI [-35;+119], second cut: Pearson r=0.25, P=0.56, 95% CI [-101;+61]).
Conclusions: :
Preconditioning of corneas with Thin-C improved the quality of the graft interface in UT-DSAEK. Histological and UBM measurement of corneal thickness showed no significant correlation in this small sample. There was no significant advancement of the cut precision of the microkeratome seen in corneas preconditioned in Thin-C or Medium II.
Keywords: cornea: endothelium • transplantation • microscopy: light/fluorescence/immunohistochemistry