Abstract
Purpose: :
In order to improve our understanding of the mechanisms responsible for Descemet membrane (DM) detachment and graft adhesion in Descemet membrane endothelial keratoplasty (DMEK), the purpose of the present study was to precisely define the nature of the attachment between DM and posterior corneal stroma and the exact cleavage plane after mechanical stripping of DM using transmission electron microscopy and immunohistochemistry.
Methods: :
Corneoscleral buttons from 15 donors aged 71.5±4.3 years were stored in OptisolTM-GS and used for DMEK surgery in 15 consecutive patients. Remaining peripheral endothelial cell-DM-complexes (EDM) and corresponding corneoscleral rims (CSR) were investigated by transmission electron microscopy and immunohistochemistry using a panel of antibodies against adhesive matrix proteins.
Results: :
Connection between DM and corneal stroma was mediated predominantly by projecting stromal collagen fibers and amorphous material of the interfacial matrix containing adhesive matrix proteins, such as fibronectin, vitronectin, amyloid P, osteonectin/SPARC, fibulins-1,-2,-3, fibrillin-1, and keratoepithelin. After DM stripping, the cleavage plane was consistently located between the interfacial matrix and posterior stromal collagen lamellae providing a largely smooth anterior EDM surface exposing the interfacial zone. Marked 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. The presence of surface irregularities was not associated with donor age, post-mortem time, and storage time of donor tissue.
Conclusions: :
The findings demonstrate the existence of a physiological cleavage plane between the anteriormost adhesive zone of DM and the corneal stroma suggesting a relatively weak attachment that can be disconnected by mechanical forces. Interindividual variations in structure and composition of the interfacial matrix may provide an explanation for the variable attachment of EDM grafts to the recipients’ corneal stroma and may thus affect the postoperative clinical outcome.
Keywords: cornea: endothelium • microscopy: electron microscopy • cornea: clinical science