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EW INTERNATIONAL 116 October 2016 by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer time to get the measurement right. We also make sure that the descem- etorhexis is larger than the graft diameter," Dr. Sekundo said. "Some surgeons, particularly those who do not operate in large numbers, buy corneal bank-pre- pared DMEK grafts. These are more expensive, however, if you only do three or four a month, you may not have enough experience to prepare the Descemet's membrane and endothelium safely and you run the risk of wasting the cornea. We are a fairly high volume institution and have become skilled in graft prepara- tion. We've prepared more than 800 grafts, with only one case where we had to abandon a cornea, in which it was absolutely impossible to prepare the DMEK roll. We prepare corneal grafts under fully sterile conditions in the operating theatre while the patient is getting prepped for surgery in the neighboring the- atre. Both theatres have an internal connecting door," he explained. He elucidated that the donor corneal age should not be below 45 years. Descemet's rolls harvested from younger eyes can be tight and therefore difficult to unroll com- pletely without coming into contact with the cornea, which can damage the to-be-grafted endothelial cells and lead to graft failure. 2 The older the graft, the thicker Descemet's membrane is likely to be. "Descem- et's membrane has two distinct layers, the anterior layer made of collagen lamellae and proteoglycans and the posterior layer produced by graft is the first step of surgery and it is, in my opinion, more difficult than the surgery itself. It is advan- tageous to harvest the DMEK graft immediately prior to surgery," he noted. "In our institute, the surgeon that performs the surgery also creates the graft, which may take 15 to 20 minutes. We always take the white-to-white measurement of the recipient to adjust the graft size. Generally, we cut the graft 3 milli- meters smaller than the white-to- white measurement to allow enough room for the graft within the cor- nea. We worked out some tricks over in graft surgery is not only for the success of surgery, but also for graft survival. 1 The graft DMEK is a partial-thickness cornea transplant procedure that involves the selective removal of diseased portions of the Descemet's mem- brane and endothelium and the sub- sequent transplantation of a fitted donor graft. Based on his experience from more than 800 DMEK surgeries performed at his institute in Mar- burg, Dr. Sekundo considers DMEK graft preparation an important part of the surgery itself. "Preparing the Going lamellar means overcoming a steep learning curve M astering new and chal- lenging surgical tech- niques can take prac- tice—sometimes a lot of it. Corneal lamellar transplant procedures have evolved into highly sophisticated surgical techniques that spot treat diseased corneal layers and spare healthy tissue, while offering patients better visual outcomes, quicker healing, and reduced graft rejection, com- pared to penetrating keratoplasty. However, acquiring the right skills takes patience and dedication. The evolution of DMEK can be chalked up to due diligence and a good dose of lateral thinking, according to corneal transplant surgeon Walter Sekundo, MD, head, Department of Ophthalmol- ogy, Philipps University, Marburg, Germany, who thinks that the road to skilled keratoplasty can be a long one. "Lamellar keratoplasty takes time to learn. We all have a learning curve when we start something new. You might realistically have to perform close to 100 grafts before you beat the learning curve and your results become consistently good," he said in an interview with EyeWorld, speaking about a presen- tation he gave on the subject at the Ophthalmologicum Balticum Con- gress in Riga, Latvia. He said that the importance of surgical experience Practice makes perfect At the conclusion of the DMEK surgery, the blue stained graft is unfolded and pushed against the host cornea by a 5% SF6 gas bubble. Source: Walter Sekundo, MD a safe technique that produces a flattening of the cornea, reduces the depth of the anterior chamber, reduces optical aberrations, and pro- vides a wide optical zone that leaves room for complementary techniques such as crosslinking, excimer laser and/or a phakic IOL implant in seeking a more physiological type of rehabilitation for these patients. EW References 1. Alio JL, et al. Intrastromal corneal ring segments: How successful is the surgical treatment of keratoconus? Middle East Afr J Ophthalmol. 2014;21:3–9. 2. Ganesh S, et al. Intrastromal corneal ring segments for management of keratoconus. Indian J Ophthalmol. 2013;61:451–455. 3. Parker JS, et al. Treatment options for ad- vanced keratoconus: A review. Surv Ophthal- mol. 2015;60:459–80. 4. Sykakis E, et al. Corneal collagen cross-linking for treating keratoconus. Co- chrane Database Syst Rev. 2015 Mar 24. 5. Wojcik KA, et al. Role of biochemical factors in the pathogenesis of keratoconus. Acta Biochim Pol. 2014;61:55–62. 6. Zadnik K, et al. Intrastromal corneal ring segments for treating keratoconus. Cochrane Database Syst Rev. 10 June 2014. 7. Carriazo and Cosentino, 2015 ESCRS Con- gress, Barcelona; Refractive Surgery: Basic and Advanced Concepts, 2015:445–456. 8. Ezra DG, et al. Corneal wedge excision in the treatment of high astigmatism after pen- etrating keratoplasty. Cornea. 2007;26:819– 825. 9. Lugo M, et al. Corneal wedge resection for high astigmatism following penetrating kera- toplasty. Ophthalmic Surg. 1987;18:650–653. Editors' note: Dr. Carriazo is the scientific director of Clinica Carriazo in Barranquilla, Colombia. He has financial interests with SCHWIND Eye- Tech Solutions (Kleinostheim, Germa- ny). This article originally appeared in Spanish in ALACCSA-R News, Novem- ber/December 2015. It was translated by ALACCSA-R and is used here with permission from the Latin American Society of Cataract and Refractive Surgeons (ALACCSA-R). Contact information Carriazo: ccarriazo@carriazo.com Keratoconus continued from page 114

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