Abstract
Purpose: :
To investigate the structural relationship in adhesion zone along the graft/host interface in failed grafts after Descemet’s stripping with endothelial keratoplasty (DSEK).
Methods: :
From the total of 164 DSEK performed in our unit, six patients underwent penetrating keratoplasty (PK): 5 for primary graft failure and one for failure after corneal ulceration after DSEK. All PK was performed after 4 to 9 months post-DSEK. Corneal buttons were fixed for 24 hours in 4% formaldehyde solution in PBS and embedded in paraffin. For brightfield microscopy the 5-µm-thick sections were stained with hematoxylin and eosin. Digital images were obtained and stored using computed image analysis system. For three-dimensional layout reconstruction with confocal laser microscope the 10-µm-thick sections were stained sequentially for 1 minute with 1% eosin and 1% auramine. Samples were excited with 488 nm argon-ion laser and the fluorescence was collected using long pass 510 nm emission filter. We also analyzed the preoperative and postoperative clinical photographs, anterior segment Optical Coherence Tomography as well video records of procedures to find risk factors for graft failure. Specimens were additionaly examined with the use of immunohistochemistry for type IV collagen presence in graft/host interface.
Results: :
Primary graft failure was suspected in 5 eyes. Donor endothelial cell count averaged 2,870 cell/mm2. According to our findings the reasons for failure were: iatrogenic endothelial trauma (3 eyes), improper donor disc position (2 eyes). In eye with ulcer (and not primary failure), the zone of adhesion was significantly thinner than in primary failed grafts. In one eye no cause of graft failure could be find. The only finding was moderately thick zone of graft adhesion. We found that both eyes with graft missdirection were extremely thick preoperatively. Four of the six eyes underwent DSEK combined with additional procedures (phacoemulsification, anterior chamber lens exchange, scleral fixation of IOL).
Conclusions: :
In thick corneas with poor intraoperative visualization the likelihood of graft missdirection seems to be greater. After succesful grafting the zone of adhesion is thinner than in failed grafts. Combined procedures could increase the risk for graft failure in DSEK.
Keywords: cornea: clinical science • pathology: human • transplantation