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Pull-through technique for delivery of a larger diameter DMEK graft using endothelium-in method

2017; Elsevier BV; Volume: 52; Issue: 5 Linguagem: Inglês

10.1016/j.jcjo.2017.03.006

1715-3360

Vito Romano, Alessandro Ruzza, Stephen B. Kaye, Mohit Parekh,

Corneal Surgery and Treatments

Busin et al. recently reported the results of an innovative surgical technique, describing the delivery of trifolded (endothelium-in) Descemet membrane (DM) endothelial keratoplasty (DMEK) graft using a pull-through technique.1Busin M. Leon P. Scorcia V. Ponzin D. Contact lens-assisted pull-through technique for delivery of tri-folded (endothelium in) DMEK grafts minimizes surgical time and cell loss.Ophthalmology. 2016; 123: 476-483Abstract Full Text Full Text PDF PubMed Scopus (63) Google Scholar We performed a similar (n = 9), but in vitro, study with larger DMEK grafts (9.5 mm) to evaluate surgical endothelial cell loss (ECL) and the learning curve. We intentionally used larger DMEK grafts because it has been demonstrated that they increase graft survival after ultra-thin Descemet stripping automated endothelial keratoplasty (UT-DSAEK).2Romano V. Tey A. Hill N.M. et al.Influence of graft size on graft survival following Descemet stripping automated endothelial keratoplasty.Br J Ophthalmol. 2015; 99: 784-788Crossref PubMed Scopus (30) Google Scholar A written consent from the donor's next of kin was obtained before the use of tissues for research purposes. The tissue was stripped and trifolded by using acute forceps (E. Janach, Como, Italy) to manipulate the DM with the endothelial side facing inward to avoid potential endothelial damage. Using the same forceps, the graft was gently pulled inside a 2.2 intraocular lens (IOL) cartridge (Viscoject, Wolfhalden, Switzerland), maintaining the graft in the same orientation (DM side touching the cartridge bottom and the endo-in on the top). Using 25G end-grasping forceps (Grieshaber forceps; 25G Alcon, Tex.), the graft was pulled inside the funnel of the IOL containing sterile phosphate-buffered saline (PBS) ready for delivery.3Parekh M. Ruzza A. Ferrari S. Busin M. Ponzin D. Pre-loaded tissues for Descemet membrane endothelial keratoplasty.Am J Ophthalmol. 2016; 166: 120-125Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar After the DM-endothelium was removed, the cornea was mounted on an artificial anterior chamber (AAC; Moria, Antony, France). The pressure inside the AAC was controlled by adjusting the height of an infusion bottle at 20 cm (15.3 mm Hg).4Romano V. Steger B. Chen J.Y. et al.Reliability of the effect of artificial anterior chamber pressure and corneal drying on corneal graft thickness.Cornea. 2015; 34: 866-869Crossref PubMed Scopus (17) Google Scholar At the 12 o'clock surgical position, a 3-mm limbal incision was made with a slit knife. Three side ports were created at the 10:30, 1:30, and 7:30 clock positions. The cartridge was inverted so that the exposed DM side was on the top of the funnel and the flaps on the bottom to facilitate opening the graft inside the eye. The IOL introducer cartridge was then inserted through an incision, and the graft was pulled from the opposite side by using end-grasping forceps. An air bubble was then used to attach the unfolded graft to the donor corneal stroma. The cornea was dismounted from the AAC and the graft gently removed using PBS and stained with trypan blue for 20 seconds followed by a wash with PBS. Placed in a hypotonic (sucrose - 1.8%) solution in a petri plate, the endothelium was examined for damage, ECL, and uncovered areas by using an inverted microscope (Primovert; Zeiss, Milan, Italy). The cells were counted by using a 10 × 10 eye piece reticule. Time required for stripping, loading, injecting, unfolding and the total surgery time were recorded. All the tissues were successfully peeled in one attempt (100% success rate). On average, 18.78 ± 5.65 minutes were required to prepare a prestripped DMEK graft in the Eye Bank. Poststripping, postloading and postdelivery mean endothelial cell density, mortality, uncovered area, time intervals, and total time of the procedure are listed in Table 1. We did not observe any disorientation of the graft in any of the 9 cases. The ECL at the end of the procedure was 22.28%, which is less than that reported for DMEK surgery (endothelium-out) of 35% to 37% at 6 months.5Rodríguez-Calvo-de-Mora M. Quilendrino R. Ham L. et al.Clinical outcome of 500 consecutive cases undergoing Descemet's membrane endothelial keratoplasty.Ophthalmology. 2015; 122: 464-470Abstract Full Text Full Text PDF PubMed Scopus (160) Google ScholarTable 1Endothelial cell loss and surgical timingEndothelial cell evaluation Poststripping endothelial cell density (ECD) (cells/mm2)2044.44 ± 427.53 Poststripping mortality (%)0.52 ± 0.99 Poststripping uncovered areas (%)0.17 ± 0.35 Postloading ECD (cells/mm2)2000.00 ± 409.27 Postloading mortality (%)0.59 ± 0.96 Postloading uncovered areas (%)0.29 ± 0.43 Postdelivery ECD (cells/mm2)1588.89 ± 321.89 Postdelivery mortality (%)0.79 ± 1.00 Postdelivery uncovered areas (%)17.84 ± 24.19Timing (min)Time to prepare1.07 ± 0.29Time to inject3.51 ± 1.00Time to unfold5.84 ± 3.95Total time10.42 ± 3.68 Open table in a new tab We had similar results in a previous in vitro study, in which we compared the ECL and total time of the surgery after injecting a 9.5-mm DMEK graft with endothelium flapped in or rolled out.6Parekh M. Ruzza A. Ferrari S. et al.Endothelium-in vs endothelium-out for DMEK graft preparation and implantation.Acta Ophthalmol. 2017; 95: 194-198Crossref PubMed Scopus (35) Google Scholar In addition, a 9.5-mm DMEK graft will transplant increased numbers of cells initially and may help in maintaining an adequate number of functional endothelial cells in the long term. It is worth considering that an increase from an 8.25-mm to a 9.5-mm diameter graft would result in transplanting approximately 20% more cells.2Romano V. Tey A. Hill N.M. et al.Influence of graft size on graft survival following Descemet stripping automated endothelial keratoplasty.Br J Ophthalmol. 2015; 99: 784-788Crossref PubMed Scopus (30) Google Scholar, 7Amann J. Holley G.P. Lee S.B. Edelhauser H.F. Increased endothelial cell density in the paracentral and peripheral regions of the human cornea.Am J Ophthalmol. 2003; 135: 584-590Abstract Full Text Full Text PDF PubMed Scopus (128) Google Scholar Even compared with the very low ECL of 9.9% reported by Busin et al.,1Busin M. Leon P. Scorcia V. Ponzin D. Contact lens-assisted pull-through technique for delivery of tri-folded (endothelium in) DMEK grafts minimizes surgical time and cell loss.Ophthalmology. 2016; 123: 476-483Abstract Full Text Full Text PDF PubMed Scopus (63) Google Scholar a larger (9.5-mm) graft with an ECL of 22.28% would still provide a greater number of cells compared with a 8.25-mm graft with a 9.9% ECL. Using the method proposed by Unterlauft et al.8Unterlauft J.D. Weller K. Geerling G. A 10.0-mm posterior lamellar graft for bullous keratopathy in a buphthalmic eye.Cornea. 2010; 29: 1195-1198Crossref PubMed Scopus (8) Google Scholar for estimating the area of the endothelial corneal surface, 8.25 mm and 9.5 mm grafts will have areas of approximately 124.9 mm2 and 156.9 mm2, respectively.7Amann J. Holley G.P. Lee S.B. Edelhauser H.F. Increased endothelial cell density in the paracentral and peripheral regions of the human cornea.Am J Ophthalmol. 2003; 135: 584-590Abstract Full Text Full Text PDF PubMed Scopus (128) Google Scholar If the preoperative endothelial cell density of the donor corneoscleral disc was, for example, 2700 cells/mm2, an increment from a 8.25-mm diameter to a 9.5-mm diameter graft would result in transplanting of approximately 424,000 cells (9.5 mm) rather than 339,705 cells (8.25 mm). Even if the ECL is 9.9% with an 8.25-mm graft and 22.28% with a 9.5-mm graft, the remaining number of cells that will be transplanted with a 9.5-mm graft (330,720 cells) will still be substantially greater than that with an 8.5-mm graft (306,000 cells). Although these calculations are speculative, such a procedure may potentially translate to higher graft survival, as also suggested by Anshu et al.9Anshu A. Price M.O. Price Jr, F.W. Descemet stripping automated endothelial keratoplasty for Fuchs endothelial dystrophy—influence of graft diameter on endothelial cell loss.Cornea. 2013; 32: 5-8Crossref PubMed Scopus (16) Google Scholar We observed that similar to 9.5-mm UT-DSAEK grafts, larger DMEK grafts were easier to handle in terms of folding and loading compared with smaller grafts. This is also highlighted by no significant ECL during loading time. The time required for the entire procedure was 10.42 ± 3.68 minutes, and this may give an additional advantage to the surgeons. Despite the limitations of this in vitro study, the results suggest that the described technique using large (9.5-mm) grafts for DMEK has an acceptable ECL and learning curve and therefore may be useful for the long-term survival of grafts compared with that of smaller grafts. The authors have no proprietary or commercial interest in any materials discussed in this article.