Lamellar Endothelial Keratoplasty Research Articles

Belgian Endothelial Surgical Transplant of the Cornea (BEST cornea) protocol: clinical and patient-reported outcomes of Ultra-Thin Descemet Stripping Automated Endothelial Keratoplasty (UT-DSAEK) versus Descemet Membrane Endothelial Keratoplasty (DMEK) – a multicentric, randomised, parallel group pragmatic trial in corneal endothelial decompensation

ObjectivesCorneal blindness is the third most frequent cause of blindness globally. Damage to the corneal endothelium is a leading indication for corneal transplantation, which is typically performed by lamellar endothelial...

Improvement of an Effective Protocol for Directed Differentiation of Human Adipose Tissue-Derived Adult Mesenchymal Stem Cells to Corneal Endothelial Cells.

Corneal disease affects 12.5 million individuals worldwide, with 2 million new cases each year. The standard treatment consists of a corneal transplantation from a human donor; however, the worldwide demand significantly exceeds the available supply. Lamellar endothelial keratoplasty, the replacement of only the endothelial layer of the cornea, can partially solve the problem. Progressive efforts have succeeded in expanding hCECs; however, the ability to expand hCECs is still limited, and new sources of CECs are being sought. Crucial advances have been achieved by the directed differentiation of embryonic or induced pluripotent stem cells, but these cells have disadvantages, such as the use of oncogenes, and are still difficult to establish. We aimed to transfer such knowledge to obtain hCECs from adipose tissue-derived adult mesenchymal stem cells (ADSC) by modifying four previously published procedures. We present several protocols capable of the directed differentiation of human ADSCs to hCECs. In our hands, the protocol by Ali et al. was the best adapted to such differentiation in terms of efficiency, time, and financial cost; however, the protocol by Wagoner et al. was the best for CEC marker expression. Our results broaden the type of cells of autologous extraocular origin that could be employed in the clinical setting for corneal endothelial deficiency.

Combined cataract surgery and lamellar endothelial keratoplasty in iridocorneal endothelial syndrome

The case is reported of a 59-year-old woman, who reported decreased visual acuity (VA) in the left eye (LE). On examination, a corrected VA of finger count/ 30cm was observed in LE. Corneal oedema and folds in the Descemet's membrane were observed using the slit lamp. Anterior synechiae, iris atrophy, and corectopia were also found. Iridocorneal endothelial syndrome (ICE) was diagnosed. The treatment option was a combination of cataract surgery and automated endothelial keratoplasty with Descemet's membrane dissection (DSAEK). There were no complications during the operation, with a successful anatomical and functional recovery, with a VA of 0,8 being observed after one year. This result supports the efficacy of DSAEK in ICE syndrome, encouraging more studies to be carried out that should also support its efficacy in this syndrome.

Indications for intraoperative anterior segment optical coherence tomography in corneal surgery

PurposeRecently, intraoperative optical coherence tomography (iOCT) has evolved in the field of ophthalmic surgery. So far, the use of iOCT was mainly focused to lamellar keratoplasty, especially deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK). The aim of this study was to report our experiences with iOCT to introduce new possibilities of this application.MethodsWe used iOCT in 18 patients who underwent the following surgeries: DALK, DMEK, penetrating keratoplasty, autologous limbal transplantation, transscleral suture fixation of a posterior chamber lens, pannus removal on corneal surface and newborn investigation in Peters’ anomaly. We obtained qualitative video data for all procedures.ResultsWith the iOCT, the cannula placement during DALK preparation of the recipient cornea and bubble formation could be visualized to improve the success rate of the big bubble injection. In DMEK, the iOCT enables the visualization of Descemet’s membrane removal in the recipient and graft orientation as well as better control of graft attachment. The iOCT enables intraoperative visualization of the graft–host interface during penetrating keratoplasty. During autologous limbal transplantation, transscleral suture fixation of a posterior chamber lens and removal of corneal surface pannus the iOCT is capable of showing the thickness of lamellar preparations to avoid penetrations and to save healthy recipient’s tissue.ConclusionThe iOCT is a helpful device for intraoperative anterior segment imaging not only for DALK and DMEK. It is also beneficial in penetrating keratoplasty and every other form of lamellar preparation during corneoscleral surgery.

Greffe lamellaire endothéliale assistée au laser Excimer (ExALEK) : technique et résultats

The purpose of this study is to describe a technique for thin endothelial lamellar keratoplasty and to present the results for endothelial transplant performed at the University Hospital of Nantes. This paper is a retrospective, single-center descriptive study conducted at the University Hospital of Nantes from September 2010 to May 2014, at first for anatomical or analgesic indications (group 1) and then extended to visual indications (group 2). Patients were followed for 12 months. The preparation of the endothelial graft includes an excimer-laser ablation of the residual stromal bed after lamellar keratectomy by manual deep anterior approach. Seventy surgeries were analyzed. The etiologies were mainly Fuchs Dystrophy, secondary endothelial dystrophy and post-penetrating keratoplasty endothelial failure. Fifty-three patients were integrated in group 1 and seventeen patients in group 2. In group 1, the mean VA at 12 months was 0.70 ± 0.30 Log MAR (0.2 decimal equivalent). In group 2, the mean VA at 12 months was 0.28 ± 0.12 Log MAR (0.5 decimal equivalent). Pachymetry decreased from 740 ± 125.1 μm preoperatively to 613.4 ± 73.4 μm at 12 months. The average central thickness of the graft was 84.1 ± 28.9 μm at 1 month and 80.2 ± 29.4 μm at 12 months. The advantage of this new surgical technique is that it is a rapid and repeatable method allowing thin grafts with satisfactory functionality and easy handling. Its performance independent of the scheduled surgery, allows for predictable organization in the operating room.

Evolution of Corneal Graft Survival Over a 30-Year Period and Comparison of Surgical Techniques: A Cohort Study

To compare graft survival between 3 10-year periods and according to surgical techniques performed in the last years. Cohort study. setting: Regional center (Besançon University Hospital, France). All 1132 patients operated on between 1983 and 2014. Graft and patient baseline characteristics, risk factors for failure, surgical procedures, and postoperative corneal status were collected. Five-year survival rate in the whole cohort; 1-year and 3-year survival rates, respectively, among 88 patients with endothelial dystrophy (ED) or postoperative bullous keratopathy (PBK) operated on using endothelial lamellar keratoplasty (ELK) or penetrating keratoplasty (PK), and among 56 patients with keratoconus operated on using anterior lamellar keratoplasty (ALK) or PK. Between the 1983-1993 and the 2004-2014 periods, overall 5-year graft survival rate increased from 61.4% to 76.5% (P = .0004). The main prognostic factors were preoperative diagnosis, graft endothelial density, and postoperative lens status. After adjusting for these factors, difference in survival rates was no longer significant (hazard ratio 0.90 for the second and 1.17 for the third period, compared to the first, P = .4191). Only 1 graft failure, after PK, occurred among the 56 patients with keratoconus. Among the 88 patients with ED or PBK, the 1-year graft survival was higher with PK (90.6%) than with ELK (60.8%) (P = .0025) but no significance remained after adjustment (hazard ratio 3.22, P = .1304). Despite numerous changes in graft procedures and surgical techniques, no noticeable improvement in graft survival was found during the last 30 years while taking into account other prognostic factors.

Effect of 60 kHz and 150 kHz Femtosecond Lasers on Corneal Stromal Bed Surfaces: A Comparative Study

Purpose. To compare the effect of 60 kHz and 150 kHz femtosecond (FS) laser on the corneal stromal bed surfaces (SBS). Methods. Sixteen human donor corneal tissues unsuitable for transplantation were used. Anterior and posterior lamella was obtained using 60 kHz and 150 kHz FS laser. A standard depth of 400 μm was set for anterior lamellar keratoplasty (ALK) and endothelial lamellar keratoplasty (ELK). The quality and smoothness of the SBS post-FS laser dissection were graded for statistics. Results. No intraoperative complications were found. The side cuts were straight, and the SBS appeared smoother in cuts obtained using 150 kHz. The average values of the SBS quality of the anterior lamellar cut were found to be 2.25 (±0.28) for 60 kHz and 3.125 (±0.25) for 150 kHz (P = 0.0039). Whereas, 2 (±0.4) for 60 kHz and 2.75 (±0.28) for 150 kHz (P = 0.0273) was the quality observed in endothelial cuts. No significant difference was found between anterior and posterior cuts performed using the same FS laser (60 kHz or 150 kHz) (P > 0.05). Conclusions. The 60 kHz and 150 kHz FS lasers are equally effective in performing lamellar dissection for ALK and ELK. 150 kHz FS laser allows a tighter spot and layer separation which creates a slightly smoother SBS.

Modern corneal and refractive procedures

Recent advances in technology and our understanding of corneal physiology have led to a rapid progression in available corneal and refractive surgical procedures. In contrast to the past, penetrating keratoplasty is no longer the only intervention of choice. Lamellar keratoplasty has gained a renewed interest and newer approaches, such as phototherapeutic keratectomy, laser-assisted in situ keratomileusis, intrastromal corneal ring segments, corneal collagen crosslinking, deep anterior lamellar keratoplasty and endothelial keratoplasty, are improving and becoming increasingly popular. This article is intended to be an overview of the modern corneal procedures, divided into three categories: anterior cornea, including those involving the epithelium, Bowman’s layer and anterior stroma; stromal; and posterior cornea, including those involving the posterior stroma, Descemet’s membrane and endothelium. Newer and experimental corneal procedures are also discussed.

Deep Lamellar Endothelial Keratoplasty Histopathology of Complications in Initial Cases

To report complications encountered after 2 initial cases of deep lamellar endothelial keratoplasty. Review of clinical findings of 2 initial cases in which intraoperative and postoperative complications were encountered. Corneal buttons from the 2 cases were evaluated by light microscopy and transmission electron microscopy. Complications encountered were related to the graft-recipient interface and the lamellar dissection of the recipient and donor corneas. Deep lamellar endothelial keratoplasty is an evolving procedure that shows much promise. These 2 cases show that the procedure entails a separate skill set from penetrating keratoplasty and requires significant surgeon practice before being introduced into the individual's transplant practice.

Component surgery of the cornea.

Penetrating keratoplasty (PKP) has long been the standard procedure for treating irreversible opacification of the cornea from various diseases. The success rate of PKP is high compared with those in other organ transplants because of the low incidence of immunologic rejection. However, once rejection does occur, secondary procedures are inevitably less successful. Cases with vascularized corneas are also prone to undergo rejection, and severe disease causing total destruction of limbal tissue is considered a contraindication for surgery. Recent advances in corneal surgery aim at reducing surgical trauma to the host cornea by replacing only necessary cells and tissue. This approach not only reduces the risk of immunologic rejection but may also yield better refractive results. The various transplantable "components" of the cornea include the epithelium, epithelial stem cells, stroma, and endothelium. Cells from these components can be transplanted as lamellar sections of donor cornea or as sheets using biologic carriers and scaffolds. Procedures such as epithelial sheet transplants using amniotic membrane carriers, deep lamellar keratoplasty, and endothelial lamellar keratoplasty are already in clinical practice. Further refinements in technology will certainly take the limits of corneal surgery to new horizons.

Discussion by

Dr. Terry and Ms. Ousley describe the 6-month and 12-month data for the first U.S. clinical trial of a new surgical approach for the correction of corneal edema secondary to endothelial cell failure. Corneal edema from endothelial cell dysfunction, as in Fuchs’ dystrophy, aphakic bullous keratopathy, and pseudophakic bullous keratopathy, is the leading cause for penetrating keratoplasty in this country. Penetrating keratoplasty (PK) is still the gold standard for endothelial replacement in treating these diseases. Recently, new surgical techniques have been devised to replace only the posterior stroma and endothelium in a lamellar fashion. These procedures include: deep lamellar endothelial keratoplasty (DLEK), as described by Dr. Terry; endokeratoplasty, as described by Drs. Bussin and Arffa; endothelial lamellar keratoplasty, as described by Dr. Culbertson; and microkeratome-assisted posterior keratoplasty, as described by Dr. Azar.

Endothelial replacement: flap approach.

The concept of selectively transplanting the corneal endothelium has been contemplated since the middle of the twentieth century. Procedures leading up to and including endothelial lamellar keratoplasty are described and discussed in this article.