Descemet’s membrane endothelial keratoplasty advances

A new technique for manipulating endothelial grafts onto the posterior corneal stroma of eyes undergoing Descemet’s membrane endothelial keratoplasty (DMEK) can speed up the surgical procedure and reduce the graft detachment and partial detachment rate, said José Güell MD, Autonomous University of Barcelona, Barcelona, Spain. “This technique allows us to significantly reduce our intraocular membrane manipulation time, independent of donor age or preservation method, and also reduces our re-bubbling rate,” Dr Güell said at Femto 2013, an international meeting on anterior segment surgery. The new technique involves the use of bimanual infusion with inferior iridectomy and transitory 20 per cent partial tamponade with sulphur hexafluoride (SF6) gas. As in air and gas tamponades in vitreoretinal surgery, the technique requires the postoperative cooperation of the patient, who, for the first postoperative week must position the head in three different positions, 15 to 20 minutes at each position, for two hours in the morning and two hours in the afternoon. In a study involving 15 consecutive eyes of 15 pseudo-phakic patients who underwent the new technique, mean uncorrected and best spectacle corrected visual acuities were 0.4 and 0.85, respectively at one month follow-up. That compares to respective values of 0.20 and 0.52 preoperatively. In addition, the mean time period between the main incision closure and final membrane positioning was four minutes and 10 seconds. That compares to a mean of 10 minutes and six seconds for the classic DMEK technique at his centre, Dr Güell said. Furthermore, re-bubbling was only necessary in one case (6.6 per cent) compared to a rate of 18 per cent in eyes undergoing classical DSEK. Advances in endothelial keratoplasty He noted that endothelial keratoplasty has undergone a steady evolution since first introduced into clinical practice at the close of the last century, with endothelial grafts becoming thinner and thinner, up to the point where now, with DMEK, the graft consists completely of endothelium and Descemet’s membrane. All of the endothelial keratoplasty techniques have the advantages over penetrating keratoplasty of improved tectonic strength, minimal induction of astigmatism and speedier visual recovery. However, in all except DMEK, the best- corrected visual acuity patients can achieve with endothelial grafts is limited by the reduced corneal clarity caused by a stroma- to-stroma interface. In addition, research shows that the immune rejection rate of DMEK grafts at two year’s follow-up is only one per cent, compared to 12 per cent for DSEK and 18 per cent for penetrating keratoplasty. There are also fewer posterior corneal higher order aberrations and visual distortions associated with DMEK. However, classical DMEK is a more difficult technique than DSAEK, and the graft tissue has a higher rate of detachment or partial detachment postoperatively, necessitation re-bubbling procedures to manipulate the graft back into place. Dr Güell said that as he gains experience with his new technique his results have continued to improve. In 30 eyes in which he has carried out the procedure since November 2012 up to April 2013, not a single case has required re-bubbling. “Multicentre prospective long-term studies are needed to evaluate this technique and possible future improvements in research on substances to initiate and/or stimulate cellular proliferation will definitely improve this approach,” he added.