EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/194331
58 EW CORNEA October 2013 Tools & techniques Descemet's stripping automated endothelial keratoplasty graft insertion by Alejandro Cerda, MD A lthough endothelial keratoplasty is moving in the direction of transplantation of only Descemet's membrane and endothelium (DMEK) or perhaps one day only endothelial cells, DSAEK still remains the predominant procedure for treating endothelial disease and compromise. There are many different means of implanting the endothelial graft, and the reality is there are few studies demonstrating that one technique is any better than another. Each surgeon may have his or her favored technique, instrument, or injection system for this procedure. This year, our practice had the pleasure of hosting Chilean surgeon Alejandro Cerda, MD, for an observer fellowship in complex cataract and anterior segment surgery. During his stay here, Dr. Cerda had endeared himself to our clinic and surgical center staff. He is a kind, composed gentleman with excellent clinical acumen. He is also an accomplished illustrator. And, despite the cultural differences, he was quickly able to appreciate my dry and sometimes bizarre sense of humor. Dr. Cerda's goal was to learn various methods of corneal transplantation in addition to complicated anterior segment surgery. He moved his entire family to Eugene, Ore., and had the opportunity to get to know life in a small U.S. town. He finished the adventure with a massive road trip to most of the major western U.S. national parks and sites. We attempted to teach him as much as possible of our various surgical approaches to anterior segment surgery and found that he was quick to learn and also quick to innovate his own surgical techniques. In this month's column, he demonstrates an alternative method for endothelial keratoplasty insertion. I hope the corneal surgeons out there will find his technique interesting and give it a try. Richard Hoffman, MD, Tools & techniques editor E ndothelial keratoplasty has transformed the field of corneal transplantation. Over the past 10 years, surgeons have moved away from penetrating keratoplasty as the standard therapy for corneal edema to the selective replacement of defective endothelium through evolving endothelial keratoplasty (EK) techniques.1 Descemet's stripping automated endothelial keratoplasty (DSAEK)3,4 is the most commonly performed method of endothelial keratoplasty. Current DSAEK graft insertion techniques include standard forceps insertion,5,6 suture pull-through,6,7 Busin glide with forceps pullthrough,2 Sheets glide with 30-gauge needle push-through,9 and various injector devices.10,11 Each method has its own advantages and disadvantages and surgeon preferences. In this article, a new graft insertion technique for DSAEK using a Busin glide (Moria, Antony, France) with a bent 27-G needle instead of a forceps is described. This needle pull-through technique is a modification of the graft insertion technique described by Busin et al.2 The Busin glide is used to roll up the tissue in combination with a bent 27G needle inserted from across the anterior chamber and pull the graft into the eye. This technique allows the surgeon to insert, center, unfold, and fixate the tissue with an injected air bubble using a single maneuver. Description of surgical technique Following preparation of the donor tissue and stripping of Descemet's membrane, a 1¼'' 27-G needle is prepared on a 3 ml syringe by making a very short bend of the tip (0.1– 0.2 mm) 90 degrees away from the bevel. The endothelial tissue is placed on a Busin glide with balanced salt solution and positioned with the bent 27-G needle leaving the rolled edge slightly exposed from the glide (Figure 1). The 3 ml syringe is filled with air and the 27G needle is bent to a 75 degree angle at the base (Figure 2). An anterior chamber infusion of balanced salt solution is utilized with low flow from a bottle height of 10 inches above the patient's eye. The 27-G needle is inserted through a 1.0 mm Figure 1: Positioning the graft on the Busin glide with the 27-G bent needle Figure 3: 27-G bent needle inserted through a nasal paracentesis, across the anterior chamber and out through the temporal main incision to engage the graft inside the Busin glide nasal paracentesis and passed across the anterior chamber and out through the temporal main incision (Figure 3). The edge of the graft in the Busin glide is engaged with the bent tip of the 27-G needle. The Busin glide and the needle are then inserted into a 4.5 mm temporal clear corneal incision while the needle is pulling the graft into the anterior chamber. Once the graft is inserted, it is centered with the needle followed by injection of air to completely unfold the graft and fixate it to the recipient cornea (Figure 4). Twelve minutes after the anterior chamber has been completely filled with air, half of the air is exchanged for balanced salt solution, and the pupil is dilated with phenylephrine 2.5% and mydriacyl 1%. Advantages of the technique Surgeons have tried many methods for insertion techniques of posterior lamellar grafts besides the forceps method, but publications of large series utilizing these methods is lacking. The use of a 30-G needle in DSAEK was first described by Koening et al to center, fixate, and unfold the graft after insertion with forceps,5 and then Balachandran et al used a 30-G needle to push in the graft over a plastic glide.8 Figure 2: 27-G bent needle Figure 4: Insertion and centration of the graft with the 27-G needle with injection of an air bubble to unfold and fixate the donor tissue to the recipient Source (all): Alejandro Cerda, MD Laboratory studies by Terry et al12 and clinical studies by Price et al13 demonstrated that incisions of 3.0 to 3.2 mm caused more endothelial damage than 5.0 mm wounds due to more wound compression from the smaller incision. This greater damage from tissue passing through smaller incisions appears to hold true regardless of what insertion technique is employed for tissue placement. The smaller incision size of 4.5 mm used for the Busin glide should also result in less surgically induced astigmatism than a 5.0 mm forceps incision. This may or may not be significant due to past observations that 5.0 mm sutured temporal clear cornea incisions had similar amounts of induced astigmatism as a 3.5 mm non-sutured incision following suture removal.14 With the bent 27-G needle the graft is engaged and pulled inside the Busin glide where it folds with the endothelium inward in an atraumatic double roll configuration leaving only the stromal face of the tissue in contact with the metal wall of the glide. The lack of a true fold in the tissue, as occurs with a folding forceps, should result in less endothelium damage from tissue compression. Another advantage of the Busin glide technique is that