Corneal Transplant

About: Corneal Transplant is a research topic. Over the lifetime, 1031 publications have been published within this topic receiving 22604 citations.

Global Survey of Corneal Transplantation and Eye Banking

Abstract: Importance Corneal transplantation restores visual function when visual impairment caused by a corneal disease becomes too severe. It is considered the world’s most frequent type of transplantation, but, to our knowledge, there are no exhaustive data allowing measurement of supply and demand, although such data are essential in defining local, national, and global strategies to fight corneal blindness. Objective To describe the worldwide situation of corneal transplantation supply and demand. Design, Setting, and Participants Data were collected between August 2012 and August 2013 from a systematic review of published literature in parallel with national and international reports on corneal transplantation and eye banking. In a second step, eye bank staff and/or corneal surgeons were interviewed on their local activities. Interviews were performed during international ophthalmology or eye-banking congresses or by telephone or email. Countries’ national supply/demand status was classified using a 7-grade system. Data were collected from 148 countries. Main Outcomes and Measures Corneal transplantation and corneal procurements per capita in each country. Results In 2012, we identified 184 576 corneal transplants performed in 116 countries. These were procured from 283 530 corneas and stored in 742 eye banks. The top indications were Fuchs dystrophy (39% of all corneal transplants performed), a primary corneal edema mostly affecting elderly individuals; keratoconus (27%), a corneal disease that slowly deforms the cornea in young people; and sequellae of infectious keratitis (20%). The United States, with 199.10 −6 corneal transplants per capita, had the highest transplantation rate, followed by Lebanon (122.10 −6 ) and Canada (117.10 −6 ), while the median of the 116 transplanting countries was 19.10 −6 . Corneas were procured in only 82 countries. Only the United States and Sri Lanka exported large numbers of donor corneas. About 53% of the world’s population had no access to corneal transplantation. Conclusions and Relevance Our survey globally quantified the considerable shortage of corneal graft tissue, with only 1 cornea available for 70 needed. Efforts to encourage cornea donation must continue in all countries, but it is also essential to develop alternative and/or complementary solutions, such as corneal bioengineering.

Descemet's stripping with endothelial keratoplasty in 50 eyes: a refractive neutral corneal transplant.

Abstract: Purpose To evaluate early visual and refractive outcomes following treatment of corneal endothelial dysfunction with a corneal transplantation technique, Descemet's stripping with endothelial keratoplasty (DSEK). Methods Visual and refractive outcomes of the first 50 consecutive cases of DSEK performed by a single surgeon between December 2003 and July 2004 were analyzed retrospectively. The DSEK technique consisted of stripping Descemet's membrane and endothelium from a recipient cornea and transplanting the posterior stroma and endothelium of a donor cornea through a 5-mm incision. Results Results are reported for 50 eyes in 47 patients (30 women and 17 men). Mean patient age at surgery was 70 +/- 12 years (range: 34 to 89 years). Five eyes were treated for corneal edema or bullous keratopathy and 45 for Fuchs' endothelial dystrophy. Seven eyes were phakic and 43 were pseudophakic. Six months after surgery, mean manifest cylinder was 1.5 +/- 0.94 diopters (D), unchanged from preoperative cylinder of 1.5 +/- 1.0 D. Mean manifest spherical equivalent refraction was 0.15 +/- 1.5 D at 6-month follow-up compared with -0.36 +/- 1.4 D preoperatively (P = .10) At 3- and 6-month follow-up, significant improvement was noted in mean best spectacle-corrected visual acuity compared with the preoperative mean of 20/100 (P = .007). At 6-month follow-up, 31 (62%) eyes refracted to > or = 20/40 and 38 (76%) eyes saw > or = 20/50. Conclusions Compared to standard penetrating keratoplasty, DSEK causes minimal refractive change and provides rapid visual recovery for patients with endothelial dysfunction. This technique maintains the structural integrity of the cornea by preserving the recipient's epithelium, Bowman's layer, and entire stromal thickness.

Oligopotent stem cells are distributed throughout the mammalian ocular surface

Abstract: The integrity of the cornea, the most anterior part of the eye, is indispensable for vision. Forty-five million individuals worldwide are bilaterally blind and another 135 million have severely impaired vision in both eyes because of loss of corneal transparency; treatments range from local medications to corneal transplants, and more recently to stem cell therapy. The corneal epithelium is a squamous epithelium that is constantly renewing, with a vertical turnover of 7 to 14 days in many mammals. Identification of slow cycling cells (label-retaining cells) in the limbus of the mouse has led to the notion that the limbus is the niche for the stem cells responsible for the long-term renewal of the cornea; hence, the corneal epithelium is supposedly renewed by cells generated at and migrating from the limbus, in marked opposition to other squamous epithelia in which each resident stem cell has in charge a limited area of epithelium. Here we show that the corneal epithelium of the mouse can be serially transplanted, is self-maintained and contains oligopotent stem cells with the capacity to generate goblet cells if provided with a conjunctival environment. Furthermore, the entire ocular surface of the pig, including the cornea, contains oligopotent stem cells (holoclones) with the capacity to generate individual colonies of corneal and conjunctival cells. Therefore, the limbus is not the only niche for corneal stem cells and corneal renewal is not different from other squamous epithelia. We propose a model that unifies our observations with the literature and explains why the limbal region is enriched in stem cells.

CD95 ligand (FasL)-induced apoptosis is necessary for corneal allograft survival.

Abstract: Although anatomical barriers and soluble mediators have been implicated in immune privilege, it appears that the apoptotic cell death of Fas+ cells by tissue-associated CD95 ligand (Fas ligand, FasL) is an important component. One clinical example of the function of an immune privileged site is the success of human corneal transplants, where a very high percentage of transplants accept without tissue matching or immunosuppressive therapy. Since the mouse cornea expresses abundant Fas ligand and immune privilege has been implicated in the success of these transplants, we examined the role of FasL in corneal transplantation. Our results show that human corneas express functional FasL capable of killing Fas+ lymphoid cells in an in vitro culture system. Using a mouse model for corneal allograft transplantation, FasL+ orthografts were accepted at a rate of 45%, whereas FasL- grafts, or normal grafts transplanted to Fas- mice, were rejected 100% of the time. Histological analysis found that FasL+ grafts contained apoptotic mononuclear cells indicating the induction of apoptosis by the graft, while rejecting FasL- corneas contained numerous inflammatory cells without associated apoptosis. Taken together our results demonstrate that FasL expression on the cornea is a major factor in corneal allograft survival and, thus, we provide an explanation for one of the most successful tissue transplants performed in humans.

Orthotopic corneal transplantation in mice—evidence that the immunogenetic rules of rejection do not apply

Abstract: The fate of orthotopic corneal transplants has been studied in inbred strains of mice. Using a surgical technique that achieves > 95% success of syngeneic cornea grafts, it was determined that a high proportion of orthotopic cornea allografts were accepted indefinitely, irrespective of the degree of immunogenetic disparity between graft donor and recipient. Grafts that succumbed to irreversible rejection developed extensive corneal edema and intrastromal neovascularization as harbingers of corneal opacity and endothelial cell failure. The highest rate of rejection occurred among grafts that confronted their hosts with multiple minor histocompatibility antigens, with or without major histocompatibility antigens. Much lower rates of rejection (< 35%) were observed when the donors of the grafts differed from recipients at class I and/or class II major histocompatibility loci. Corneal grafts that confronted their hosts with class II MHC alloantigens alone experienced early, acute inflammation, and eventually developed stomal neovascularization, but only a small minority of these grafts were eventually destroyed. Allogeneic corneas that were transplanted orthotopically into eyes of presensitized mice were uniformly subjected to an acute rejection process that produced opacity within three weeks; however, in a minority of instances, the inflammation and opacity subside, and after eight weeks the grafts displayed a clear, nonvascularized appearance. The high rate of success of even grossly histoincompatible orthotopic corneal allografts in mice resembles the extraordinary success of unmatched allogeneic corneas transplanted into human eyes. The results are discussed in terms of the possible mechanisms that permit orthotopic corneal allografts to enjoy significantly better survival than orthotopic grafts of other types of solid tissues.