Purpose
To determine a cost-effective technique to tag the donor graft tissue using readily available surgical instruments to designate the endothelial orientation of the donor graft tissue for DMEK. We attempt to determine if donor punch trephine modification with basic surgical instruments reliably provides a partial thickness trephination of donor tissue, allowing for an asymmetric tag of descemet's membrane to be created. We also attempt to determine which method of trephine modification is faster and more effective: adson forceps (AF) or needle holder (NH).
Methods
We altered various sized donor cornea punches with either NH or AF by grasping the metal blade and bending centrally to create a blunt edge that did not cut the donor graft tissue. This blunt edge allowed for additional non-graft tissue that could be fashioned into a tag by cutting a right triangle with vannas scissors. We recorded the number of successful tags and the time for modification.
Results
16 trephines and 15 trephines ranging in size from 7-9mm were altered with AF and NH, respectively. We recorded the time for modification. Our goals were: (1) to determine whether it was faster to modify the donor punch with NH or AF and (2) which instrument was more successful for donor punch modification in order to produce a tagged endothelial graft tissue. T-Test value was 0.195 suggesting that there is no difference in the time it took to modify the donor punch with either NH or AF. Our Chi Square Test result was 0.3549 indicating that there is no difference in the success rate of the cutting the tissue when comparing the NH with the AF (i.e. did the trephine modified with NH or AF successfully produce an uncut extra non-graft tissue to tag).
Conclusions
Modification of various sized trephines with either NH or AF did not approach statistical significance in regards to one method being more effective than the other to create an extra non-graft area conducive to tag creation. There was no statistical difference between the two instruments in speed or success of trephine modification. We propose this technique to help the DMEK surgeon with graft endothelial orientation. Further research is needed to determine if this method of graft modification would translate into a higher rate of DMEK success.
Keywords: 481 cornea: endothelium