NOV 18, 2011
There remains considerable uncertainty about the detailed ultrastructure and biochemical composition of the interface between Descemet's membrane (DM) and the posterior stroma, as well as the exact localization of the cleavage plane in DM stripping during DMEK surgery. To investigate further, researchers used transmission electron microscopy and immunohistochemistry to examine corneoscleral buttons from donors for Descemet's membrane endothelial keratoplasty (DMEK) surgery.
Their findings provide evidence for the existence of a physiologic cleavage plane between the interfacial matrix, the most anterior adhesive zone of Descemet's membrane (DM), and the corneal stroma, suggesting a relatively weak attachment that can be disconnected by mechanical forces. They conclude that interindividual variations in structure and composition of the interfacial matrix may be responsible for the variable attachment of endothelial cell-DM complex (EDM) grafts to recipients' corneal stroma, thereby affecting postoperative clinical outcomes.
They found that the connection between DM and corneal stroma was mediated predominantly by amorphous material of the interfacial matrix and projecting stromal collagen fibers. After DM stripping, the cleavage plane was located consistently between interfacial matrix and posterior stromal collagen lamellae, providing a largely smooth anterior EDM surface exposing the interfacial zone. Interindividual variations in amount and composition of the interfacial matrix resulted in variable degrees of EDM surface irregularities and variable staining patterns for adhesive matrix proteins, such as fibronectin, vitronectin, amyloid P, osteonectin/secreted protein acidic and rich in cysteine (SPARC), fibulin-1, fibulin-2, fibulin-3, fibrillin-1 and keratoepithelin.
The authors conclude that this study provides a basis for more comprehensive studies to correlate structural and biochemical characteristics of the EDM surface to donor age, type of culture condition and postoperative clinical outcomes. The results of such research may suggest refinements to current DMEK techniques that may improve graft-host attachment.