Effect of microkeratome pass on tissue processing for Descemet stripping automated endothelial keratoplasty

The aim of this study was to optimize tissue preparation for Descemet stripping automated endothelial keratoplasty (DSAEK) by evaluating the outcomes of corneal tissue processing.

Forty-five corneas underwent microkeratome (MK) tissue processing for single-cut DSAEK, and 74 corneas were processed for double-cut (ultrathin) DSAEK. For single-cut processing, the corneas were cut at the thickest peripheral point (method A) or at a random location (method B). For double-cut processing, tissues were cut at the thickest peripheral point and then 180 degrees away (method C), at the thickest point and then the second thickest point (method D), or at a random peripheral starting point and then 180 degrees away (method E). The tissue was measured for corneal thickness and for endothelial cell density.

For single-cut DSAEK tissues, there was no difference in the central tissue thickness (P = 0.23), mean peripheral thickness (P = 0.57), or peripheral tissue symmetry (P = 0.27) between A and B measured by anterior segment optical coherence tomography. For double-cut (ultrathin) DSAEK tissues, tissues cut using method C or D were not statistically significantly different for perforation rate, final central corneal thickness, mean peripheral thickness, or for tissue symmetry (P = 0.57, P = 0.33, P = 0.63, P = 0.48, respectively). All 4 tissues cut using method E were perforated during the second MK pass. The perforation, or donor loss rate, for ultrathin cut tissue preparation in group C was 23%, and for group D, it was 29%. Only 65% of successfully cut tissues in groups C and D actually achieved a thickness of ≤100 μm.

Single-cut DSAEK tissue processing can be performed safely without peripheral corneal thickness measurements. Ultrathin DSAEK tissue processing requires peripheral thickness measurements for the first, but not for the second MK pass. Ultrathin DSAEK tissue processing led to high perforation rates. Certain tissue characteristics, processing techniques, and MK head size play a role in successful donor corneal tissue processing of ultrathin DSAEK tissue.