Descemet's stripping automated endothelial keratoplasty (DSAEK) is a widely performed method of corneal transplantation. It is now considered the standard of care for the treatment of endothelial cell dysfunction. The advantages of this technique include faster visual rehabilitation, decreased risk of allograft rejection, preservation of corneal tectonic strength, stable refraction, reduced irregular astigmatism, and less suture complications.
The standard of care at the Toronto Western Hospital for Dr. Rootman's and Dr. Slomovic's patients with corneal endothelial disease is to perform DSAEK surgery with the Tan Endoglide for insertion of the donor graft. Other surgeons at Toronto Western Hospital use either Busin glide or specifically designed forceps for insertion of the donor graft as part of the standard of care. Still others have advocated the use of the suture pull-through technique.
There is significant disagreement in the literature regarding the DSAEK insertion technique that best preserves the donor endothelium. Some investigators report better results with a forceps or sutures, and others caution against any folding. The less traumatic the insertion to the endothelium, the better the long term survival of the corneal transplant. In addition, surgeons also debate whether large- or small-incision DSAEK is better for the graft's long-term viability, its propensity for postoperative dislocation, and the ease of insertion in the OR. The proposed advantages of the Tan EndoGlide include consistent and reliable delivery of the corneal donor through a small incision with minimal endothelial loss. The advantages of a small-incision DSAEK are, that it provides a more stable wound postoperatively, sutureless surgery, speed, and convenience for combining the procedure with standard phacoemulsification. Balancing the attractiveness of small-incision DSAEK with the concern for endothelial injury from donor folding and forceps compression, the Endosaver (Ocular Systems, Inc., Winston-Salem, NC) a novel DSAEK injector device, has been recently introduced. It allows the surgeon to insert unfolded tissue without a forceps through a 4-mm clear corneal incision.
Both devices have been approved for use by Health Canada as a Class 1 device (http://www.angioedupro.com/Sharpoint/index.php?seek=394).
Recently, the results of a randomised prospective study being conducted by Dr. D. Tan (inventor of the Tan EndoGlide) were published. In this study the effect on endothelial cell counts using the Tan EndoGlide has been evaluated. The investigators report a 15.6% of endothelial cell loss 12 months after DSAEK surgery. There are no published studies regarding the Endosaver injector, nevertheless, preliminary results indicate poorer outcome (30% cell loss after one month). No study comparing the two devices in regard to endothelial cell loss was reported so far.
The purpose of this study is to compare the Tan EndoGlide with the new Endosaver injector in terms of damage to the donor corneal endothelium by comparing the endothelial cell loss at 1 month, 3 months, 6 months, and 1 year postoperatively. Our study would involve prospectively examining a total of 42 subjects (21 eyes with the Tan EndoGlide and 21 eyes with the Endosaver injector) and compare endothelial cell loss and visual outcomes between groups.
