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Endothelial keratoplasty: Entering a new era with evolving techniques
For many years, penetrating keratoplasty has been used for surgical treatment of blindness caused by corneal diseases. Now, corneal transplantation is marching into a new era because of the advent of lamellar surgeries, endothelial keratoplasty in particular.
In the past decade, endothelial keratoplasty, initially called posterior lamellar keratoplasty, has seen tremendous progress with improved technology. Currently, new lamellar keratoplasty techniques, such as Descemet’s stripping (automated) endothelial keratoplasty, are becoming the preferred corneal transplantation surgical procedure of many surgeons. More recently, Descemet’s membrane (automated) endothelial keratoplasty and femtosecond laser-assisted endothelial transplantation have been introduced with good success. Both safety and efficacy have been improved, making the future developments of endothelial keratoplasty very exciting and promising.
Evolution of endothelial keratoplasty
The first endothelial keratoplasty, posterior lamellar keratoplasty, was introduced by Melles in 1997 and was modified and renamed as deep lamellar endothelial keratoplasty by Terry and Ousley in 2001. In DLEK, a 5-mm scleral tunnel incision is created to facilitate the deep lamellar dissection, and an air bubble is formed in the anterior chamber to judge depth. After preparation, the donor tissue is folded and inserted into the anterior chamber. The anterior chamber is firmly filled with air for 10 minutes for positioning the donor tissue, which will be removed and replaced by balanced salt solution. However, the hand-dissection procedures are technically difficult, leading to the exploration of new techniques.
Based on the first generation, endothelial keratoplasty has rapidly evolved with the development of new techniques, such as DSEK and DSAEK. In 2004, Melles described a technique of removing the recipient’s Descemet’s membrane. Referred to as descemetorrhexis, this procedure, DSEK, was soon popularized. DSEK was further modified and referred to as DSAEK, with the use of automated microkeratome-assisted donor tissue dissection. Nowadays, these procedures have been widely reported to be a safe and effective treatment for endothelial diseases of the cornea in terms of surgical risks, complication rates, graft survival (clarity), visual acuity and graft-induced astigmatism. They are therefore the preferred surgical procedure for corneal endothelial dysfunction. However, even with these advantages, a few drawbacks, such as stromal tissue involvement during dissection of the donor cornea graft and incomplete attachment in DSEK/DSAEK, have yet to be overcome.
Continued modification aimed at exploring new methods to improve the lamellar techniques is being sought. In the current DMEK/DMAEK technique, a 3.5-mm tunnel incision in the limbus is used as the major entrance. The Descemet’s membrane is replaced using custom-made instruments. This development not only allows surgeons to transplant the Descemet’s/endothelium complex without any redundant stromal tissue, but it also improves the optical outcome of the transplanted cornea.
Future prospects
Selective lamellar transplantation has been regarded by many leading surgeons as the preferred surgical procedure for corneal transplantation in treating endothelial decompensation in terms of safety and efficacy. Endothelial keratoplasty is now giving surgeons an opportunity to replace only the diseased tissue while leaving the healthy tissue intact. Driven by clinical evidence and research data, the evolution of lamellar keratoplasty will continue to be the surgical trend. On the other hand, Descemet’s membrane endothelial transfer, the implantation of a graft into the anterior chamber without positioning to the host posterior stroma, also holds great promise. It looks likely that we are entering a new era in treating endothelial decompensation.
References:
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Melles GR, et al. Cornea. 1998;17(6):618-626.
Melles GR, et al. Cornea. 2004;23(3):286-288.
Melles GR, et al. Cornea. 2006;doi:10.1097/01.ico.0000248385.16896.34.
Price FW Jr, et al. J Cataract Refract Surg. 2006;doi:10.1016/j.jcrs.2005.12.078.
Price FW Jr, et al. J Refract Surg. 2005;21(4):339-345.
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For more information:
Dennis S.C. Lam, MD, FRCOphth, can be reached at State Key Laboratory in Ophthalmology, Sun Yat-Yen University, 54 South Xianlie Road, Guangzhou 510060, People’s Republic of China; +852-3997-3266; fax: +852-3996-8212; email: dennislam.gm@gmail.com.
Disclosure: The authors have no relevant financial disclosures.