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C. Macaluso, A. Ruzza, D. Ponzin, G. Ferrari; Evaluation of a Novel Device for Graft Insertion in Endothelial Keratoplasty. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3956.
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To quantitatively evaluate the impact on endothelial cell survival of the closed-chamber pulling-injection (CCPI) system, designed for graft insertion in Descemet stripping automated endothelial keratoplasty (DSAEK).
14 human sclero-corneal buttons underwent removal of the outer 350 µm stroma by means of a mechanical microkeratome, and 9 mm endothelial grafts were then obtained by trephination. Each graft was coloured with 0.25% Trypan blue for 30 seconds. After rinsing with normal saline, the blue areas were quantified under light microscopy, providing an estimate of the baseline endothelial damage.The CCPI device allows rolling up rather than folding the endothelial graft, avoiding contacts for the endothelium, also protected by cornea preservation medium. The endothelial grafts were placed onto the CCPI cartridge loading area and pulled through the bevelled tip to simulate their injection into the anterior chamber. CCPI cartridges with 2.8 and 2.0mm diameter tips were used, corresponding to virtually no compression/overlapping for a 9mm rolled graft (2.8mm * π = 8.8mm), or some compression/overlapping (2.0mm * π = 6.3mm), respectively. Endothelial damage was calculated as the sum of Trypan blue positive areas observed after CCPI passage, divided by the total graft area.
All the grafts passed through the CCPI device smoothly. With the 2.8mm diameter tip cartridge, the endothelial cell suffering areas increased globally by only 0.5% (one case), while with the 2.0mm tip cartridge induced damage was 1.45% (±1.7% SD; 13 cases).
Although DSAEK is becoming the preferred surgical technique for keratoplasty due to endothelial diseases, a higher survival of endothelial cells through the procedure is desirable. Handling the delicate endothelial graft during insertion appears as the most critical factor (Ide T. et al., Cornea 2007). By rolling up rather then folding the graft, the CCPI system (Macaluso C., JCRS in press) is expected to induce less damage, as the chances of mechanical contact to endothelial cells are reduced. The present results show that the CCPI system induces little loss of endothelial cells, not only with a relatively large tip (2.8mm) that allows ideal graft spacing, but also with a smaller 2.0mm tip, that results in some degree of tissue compression. To our knowledge, the CCPI technique was the first system rolling up the endothelial graft and inserting it by pulling through a device to be devised, used in the clinical setting (July 2005), and to have its potential endothelial damage assessed in a controlled experiment.
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