Descemet's membrane endothelial keratoplasty is the predominant keratoplasty procedure in Germany since 2016: a report of the DOG-section cornea and its keratoplasty registry

BACKGROUND/AIMS

This retrospective multicentric panel study provides absolute numbers, types of and indications for corneal transplantation in Germany from 2011 to 2021 and sets them into the international context.

METHODS

A questionnaire was sent to the 104 German ophthalmologic surgery departments and 93 (89%) provided their data.

RESULTS

The number of reported keratoplasties more than doubled from 2011 (n=4474) to 2021 (n=8998). Lamellar keratoplasties (49% posterior (n=2883), 4% anterior (n=231)) surpassed penetrating keratoplasty (PKP, 47%, n=2721) for the first time in 2014. Since 2016, Descemet's membrane endothelial keratoplasty (DMEK) has become the predominant keratoplasty procedure in Germany. Its number increased by 1.5-fold from 3850 (2016) to 5812 (2021). Main indications in 2021 were Fuchs' endothelial corneal dystrophy (FECD, 43%), pseudophakic corneal decompensation (12%), repeated keratoplasty (11%), infections (7%), keratoconus (6%) and corneal scarring (4%, others: 9%). The PKP percentage decreased from 70.2% in 2011 (n=3141) to 31.7% in 2021 (n=2853). Descemet's stripping (automated) endothelial keratoplasties (DSAEKs) decreased to 1% in 2021 (n=74). 98.6% of all posterior lamellar keratoplasties were DMEKs in Germany in 2021. The number of deep anterior lamellar keratoplasties (DALKs) remained comparable from 2011 (n=269) to 2021 (n=251, 2.8%).

CONCLUSION

Main indications for corneal transplantation in Germany (2021) were FECD and pseudophakic corneal decompensation. DMEK is by far the predominant corneal transplantation procedure since 2016 followed by PKP, whose absolute number decreased only slightly during the decade from 2011 to 2021. DALK proportions remain low, but stable, whereas DSAEK decreased annually and plays a minor role in Germany.

TRIAL REGISTRATION NUMBER

NCT03381794.

The Rapid Transformation of Transplantation for Corneal Endothelial Diseases: An Evolution From Penetrating to Lamellar to Cellular Transplants

The cornea is the major focusing structure of the human eye and the corneal endothelium maintains the relatively dehydrated state of the cornea required for clarity. The endothelial cells respond to disease or injury by migration and cellular enlargement. Our current understanding is that there is a very limited degree of proliferative or regenerative capacity in the human corneal endothelium. Thus, corneal endothelial diseases may result in corneal edema, significantly impact vision and quality of life. Contemporary surgical transplantation options for treating moderate to advanced endothelial dysfunction include penetrating keratoplasty (PK), Descemet stripping endothelial keratoplasty (DSEK), and Descemet membrane endothelial keratoplasty. Advances in surgical techniques aim to bring faster visual recovery and improve visual outcomes; however, there is still a significant donor cornea shortage worldwide and alternative methods for treatment for corneal endothelial disease are rapidly evolving. Indeed, we are at a pivotal point in corneal transplantation for endothelial disease and novel surgical strategies include using 1 donor for multiple recipients, a minimally attached endothelial graft, and Descemet membrane stripping only. Crucially, forthcoming approaches include the use of Rho-Kinase (ROCK) inhibitors, endothelial cell therapy, tissue engineered grafts, and consideration of stem cell techniques. Ultimately, the choice of technique will be dependent on recipient factors such as age, type of endothelial disease, extent of the disease, and associated ocular disorders. The safety and efficacy of these rapidly developing treatments warrant further investigations. In time, some or all of these alternatives for corneal transplantation will alleviate the reliance on limited corneal donor tissue.

Trends in corneal transplantation at the University Eye Hospital in Tübingen, Germany over the last 12 years: 2004 - 2015

Purpose

This study aimed to investigate the trends in the surgical methods and leading indications for corneal transplantations carried out over the last 12 years.

Methods

The data from the corneal graft waiting list and from all keratoplasties carried out between 2004 and 2015 at the University Eye Hospital in Tübingen were retrospectively analyzed.

Results

A total of 1,185 keratoplasties were performed between 2004 and 2015 at this hospital. The most common surgical indications for corneal transplantation were Fuchs’ endothelial corneal dystrophy (35.2%) and keratoconus (18.9%) with keratoconus being the leading cause during early years (from 2004 to 2009) and Fuch’s dystrophy being the leading cause from 2010 to 2015. Overall, the total count of performed keratoplasties increased, from 385 corneal transplantations during the first 6-year period to 800 corneal transplantations during the second 6-year period (P = 0.008, using Mann-Whitney test). The Descemet’s membrane endothelial keratoplasty has become the favored surgical method for endothelial disorders with the number of Descemet’s membrane endothelial keratoplasties increasing significantly from 2008 to 2015. This increasing trend was statistically significant (P < 0.001 using multivariate adaptive regression splines (MARS). A decreasing trend was also noted for the rate of penetrating keratoplasty since 2008 (P < 0.001 using MARS).

Conclusions

This research showed major changes in the preferred corneal transplantation techniques and leading indications for keratoplasty over the last 12 years. More importantly, it seems that the rapid development and implementation of endothelial keratoplasty, especially the Descemet’s membrane endothelial keratoplasty, has had a profound effect on and begun a new era in corneal transplantation.

New trends in corneal transplants at the University of Toronto

OBJECTIVE

To assess trends in surgical procedures and indications for all corneal transplants performed at the University of Toronto.

DESIGN

Retrospective cross-sectional study.

PARTICIPANTS

One thousand one hundred and four consecutive corneal transplants performed at the Kensington Eye Institute (KEI).

METHODS

Demographic, clinical, and pathological data retrieved from the Ophthalmic Pathology Laboratory on all corneal transplants performed at the KEI from January 2014 to December 2016.

RESULTS

Over 3 years, partial-thickness lamellar keratoplasties were performed in 880 cases (80%) while full-thickness penetrating keratoplasties (PKP) accounted for 224 cases (20%). Leading causes of corneal transplant were Fuchs' dystrophy (42%), graft failure (17%), bullous keratopathy (15%), and keratoconus (15%). Graft failure (40%) and keratoconus (31%) were the leading causes for PKP. Descemet's membrane endothelial keratoplasty (DMEK) accounted for 37% of cases, Descemet's stripping automated endothelial keratoplasty (DSAEK) for 30%, and deep anterior lamellar keratoplasty (DALK) for 13%. By 2016, partial-thickness procedures had increased by 10%, accounting for 85% of all procedures. In addition, DMEK increased by 26%, DSAEK decreased by 13%, and PKP decreased by 11%. Fuchs' dystrophy remained the leading indication for DMEK (67%) and DSAEK (42%) procedures. In 2016, 73% of DALK procedures were for the treatment of keratoconus.

CONCLUSIONS

Partial-thickness corneal transplants now account for 85% of all current graft procedures, and DMEK has emerged as the procedure of choice. Graft failure continues to be the leading indication for full-thickness grafts. Longitudinal studies are needed to determine whether these new trends persist and their future impact on graft failures.

Changes in Technique and Indications for Keratoplasty in Poland, 1989 to 2014: An Analysis of Corneal Transplantations Performed at Saint Barbara Hospital, Trauma Center, Sosnowiec, Poland

BACKGROUND

The purpose of this work was to study the evolving trends in techniques and indications for corneal transplantation in Poland.

METHODS

This retrospective, descriptive analysis of corneal transplantations was performed at the Ophthalmology Department of Saint Barbara Hospital, Trauma Center, Sosnowiec, Poland, between 1988 and 2014. Structure of indications and surgery type rates over 26 years were tabulated by means of 5-year intervals.

RESULTS

Between 1989 and 2014, 1762 corneal transplantations were performed, including 1375 (78%) cases of penetrating keratoplasty, 137 (8%) lamellar keratoplasty, 112 (6%) patch grafts, and 138 (8%) keratolimbal allografts. The major indications and their respective overall percentage were corneal leucoma (24%), pseudophakic/aphakic bullous keratopathy (22%), Fuchs dystrophy (13%), keratoconus (13%), re-graft (11%), keratitis (9%), and limbal stem cell deficiency (8%), with changes in relative frequency of the leading indications over the following time intervals. The number of corneal transplantations gradually increased during the years reviewed. The rates of lamellar, keratolimbal, and patch grafts have grown dynamically since 2010, reaching 20%, 17%, and 12%, respectively, of procedures performed during 2010 to 2014.

CONCLUSIONS

Over the past quarter of a century, there has been evolution in corneal transplantation service, from the first penetrating keratoplasty to the wide spectrum of procedures, including femtosecond laser-assisted keratoplasty. Although, since 2010, the rates of lamellar and keratolimbal allografts have grown rapidly, penetrating keratoplasty has remained the leading technique.

Review of developments in corneal transplantation in the regions of Brazil - Evaluation of corneal transplants in Brazil

The aim of this study was to identify inequalities in corneal donation and transplantation among the regions of Brazil. A transversal and retrospective study was specifically conducted using data from the Brazilian Transplant Registry collected by the Brazilian Association of Organ Transplantation between January 2002 and December 2014. The collected data were processed using descriptive statistical methods, and p<0.05 was the rate of rejection of the null hypothesis. From 2002 to 2014, there was an increase in the absolute number of corneal transplants, the annual rate of transplants per million people and the percentage of needed transplants performed in each of the five regions of Brazil. Family refusal and medical contraindication were the most frequent reasons for a lack of corneal donation. Although remarkable progress has been made in the last decade in each of the five Brazilian regions, health professionals' lack of preparation to approach families with donation requests at the death of a family member appears to be the main obstacle to increasing the number of corneal donations. Thus, the present study suggests the implementation of public policies to make corneal transplants more effective, particularly given that there are considerable disparities in the effectiveness with which regional needs are met and in health professionals' ability to perform transplants among the Brazilian regions, with higher rates in the South, Southeast and Midwest regions and lower rates in the North and Northeast regions.

[Corneal cross-linking as a treatment for progressive keratoconus]

Keratoconus is a corneal disease with onset typically occurring during puberty or early adulthood. The cornea progressively thins and acquires a cone-like shape which negatively affects visual acuity. In the early stages, visual acuity can be corrected with glasses or contact lenses. In more advanced cases, a corneal transplant is ultimately indicated to restore visual acuity. Corneal cross-linking (CXL) is a treatment given at a relatively early stage that protects patients against deterioration of visual acuity and further corneal deformation in progressive cases of keratoconus. The effectiveness and low complication rates have been demonstrated in multiple randomized controlled trials with long-term follow-up. Since the introduction of CXL in the Netherlands in 2007, the number of corneal transplants for keratoconus has decreased. Since 1 January 2015, the treatment has been included for reimbursement under certain conditions in the basic health insurance package in the Netherlands.

Development of Selective Lamellar Keratoplasty within an Asian Corneal Transplant Program: The Singapore Corneal Transplant Study (An American Ophthalmological Society Thesis)

PURPOSE

To evaluate outcomes of anterior lamellar keratoplasty (ALK) and endothelial keratoplasty (EK) within the Singapore Corneal Transplant Study (SCTS), with the hypothesis that both ALK and EK are able to provide equivalent or improved clinical outcomes, compared to penetrating keratoplasty (PK), and to determine changing trends globally with other international databases.

METHODS

Clinical data on all transplants performed was derived from our SCTS database, a prospective national keratoplasty registry, and clinical outcomes (graft survival, endothelial cell loss, complications, visual acuity) were compared between PK, ALK, and EK. Global trends on indications and forms of keratoplasty performed in 2011/2012 were obtained from national keratoplasty or eye banking registries, corneal/ophthalmological societies, national eye banks, and national ophthalmic institutions.

RESULTS

Global rates of EK surgery vary widely, from 52% (Sweden) to 0% (South Africa), with higher adoption by industrialized countries. ALK adoption rates similarly vary from 28.7% (China) to 1.0% (Philippines). SCTS data show high adoption rates in Singapore: EK 44% and ALK 28%. Our surgical modifications to big-bubble deep anterior lamellar keratoplasty (DALK) surgery resulted in visual outcomes matching PK, and a low conversion to PK of 2.1%, whereas our evolving approaches to donor insertion in Descemet's stripping automated endothelial keratoplasty (DSAEK) show significant reduction in 1-year postoperative endothelial cell loss rates from 60% (folding), to 22% to 30% (Sheets Glide), to 15% (EndoGlide inserter).

CONCLUSION

Improvements in various forms of ALK and EK surgery can lead to better visual outcomes, longer graft survival, and reduced complications, as compared to PK. Global trends suggest adoption of these procedures at different rates.

[Updates in corneal transplantation]

Corneal transplantation or keratoplasty has rapidly developed over the last 10 years. Penetrating keratoplasty, a well-known operation consisting of full thickness replacement of the cornea, has remained the dominant procedure for a long time. It allows appropriate therapy of most causes of corneal blindness. However, this technique is currently evolving toward slamellar keratoplasties which selectively treat the specific affected layers: deep anterior lamellar keratoplasty replaces the diseased corneal stromal layers; endothelial keratoplasty replace the affected endothelium. This article will present these techniques, and briefly discuss their advantages.

New perspectives on lamellar keratoplasty

Lamellar (anterior and posterior) keratoplasty entails the surgical replacement of diseased-only corneal tissue, while healthy host corneal tissue is preserved. Selective keratoplasty offers several advantages in comparison to penetrating keratoplasty such as a lower rate of graft rejection, less endothelial cell loss, faster/superior visual rehabilitation and enhanced resistance to closed injury. The surgical approach of "partial corneal transplantation" may be divided into anterior and posterior: techniques including superficial and deep anterior lamellar keratoplasty (SALK and DALK, respectively) and endothelial keratoplasty as well as Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK). These novel surgical procedures are rapidly becoming the preferred therapy option for specific corneal dysfunctions involving the corneal stroma (SALK, DALK), or corneal endothelium (DSAEK, DMEK). During the past decade, the continuing advancement of surgical techniques and the development of innovative surgical instruments have significantly enhanced corneal transplantation. Lamellar keratoplasty techniques facilitate corneal surgery, provide patients with superior outcomes and can successfully restore vision in corneal-related blindness. Nevertheless, more long-term evidence is needed to better evaluate these promising new techniques.

Corneal blindness and xenotransplantation

Approximately 39 million people are blind worldwide, with an estimated 285 million visually impaired. The developing world shoulders 90% of the world's blindness, with 80% of causative diseases being preventable or treatable. Blindness has a major detrimental impact on the patient, community, and healthcare spending. Corneal diseases are significant causes of blindness, affecting at least 4 million people worldwide. The prevalence of corneal disease varies between parts of the world. Trachoma, for instance, is the second leading cause of blindness in Africa, after cataracts, but is rarely found today in developed nations. When preventive strategies have failed, corneal transplantation is the most effective treatment for advanced corneal disease. The major surgical techniques for corneal transplantation include penetrating keratoplasty (PK), anterior lamellar keratoplasty, and endothelial keratoplasty (EK). Indications for corneal transplantation vary between countries, with Fuchs' dystrophy being the leading indication in the USA and keratoconus in Australia. With the exception of the USA, where EK will soon overtake PK as the most common surgical procedure, PK is the overwhelming procedure of choice. Success using corneal grafts in developing nations, such as Nepal, demonstrates the feasibility of corneal transplantation on a global scale. The number of suitable corneas from deceased human donors that becomes available will never be sufficient, and so research into various alternatives, for example stem cells, amniotic membrane transplantation, synthetic and biosynthetic corneas, and xenotransplantation, is progressing. While each of these has potential, we suggest that xenotransplantation holds the greatest potential for a corneal replacement. With the increasing availability of genetically engineered pigs, pig corneas may alleviate the global shortage of corneas in the near future.

Progress in the development of a corneal replacement: keratoprostheses and tissue-engineered corneas

Rapid progress has been made in the past 5 years in the development of corneal replacements. Traditionally they are divided into two categories, keratoprostheses and tissue-engineered corneal equivalents, as replacement tissues are increasingly in demand worldwide. There are currently several different keratoprosthesis models in clinical use around the world. The most popular and most widely publicized is the AlphaCor model, which has enjoyed significant clinical success. However, improvements remain to be made, and the aim of most of the current research is to better understand the interactions between a synthetic material and the surrounding biology on a more fundamental level. This improved understanding will no doubt lead to improvements in current models and to the development of new models in the near future. While tissue-engineered corneal equivalents have been under investigation for considerably less time, there is growing evidence to suggest that a tissue-engineered corneal equivalent comprised of primarily natural materials will exist in the not too distant future. Research groups have reported strong in vitro and in vivo results. The strength of the collagen matrix and its ability to support cell infiltration have been the primary avenues of research. Various collagen crosslinking techniques have been used. Infiltration of three major cells of the cornea has been observed. Most importantly, the ability of these materials to support nerve ingrowth has been demonstrated. While challenges remain with both types of corneal replacements, the considerable progress in the recent past suggests that reliable implants for the treatment of a variety of corneal diseases will be available. This review will provide an overview of recent results, and will provide insight into the future of research on corneal replacements.

[Selective principle of modern approaches in keratoplasty]

Currently accepted selective principle of modern therapeutic-optical keratoplasty is based on well-known advantages of target substitution of the damaged corneal layers. This article covers the variety of selective keratoplasty methods for different anatomical levels of corneal involvement. Major advantages of up-to-date keratoplasty methods involving high end surgical technologies have been analyzed.

[Ocular surface reconstruction in limbal stem cell insufficiency: transplantation of limbal tissue]

Reconstruction of the ocular surface in patients with limbal stem cell insufficiency (LSI) remains one of the most challenging tasks in ophthalmology. The transplantation of lamellar limbal tissue in total LSI represents an established therapeutic concept, while an abrasion of the conjunctival pannus allowing normal limbal epithelium to recolonize the cornea is the treatment of choice in partial LSI. Surgery must be postponed until an inflammation-free period is reached and lid abnormalities have been corrected. In unilateral total LSI autologous limbal tissue from the healthy eye is transplanted in order to circumvent immunological adverse events. In bilateral total LSI cadaveric or living related allogenic limbal tissue is used for transplantation, in which case systemic immunosuppression and HLA matching are mandatory. The combination with amniotic membrane transplantation and mitomycin C treatment can further improve long-term outcome of limbal stem cell transplantation.

Paradigm shifts in corneal transplantation

Conventional corneal transplantation, in the form of penetrating keratoplasty (PK), involves full-thickness replacement of the cornea, and is a highly successful procedure. However, the cornea is anatomically a multi-layered structure. Pathology may only affect individual layers of the cornea, hence selective lamellar surgical replacement of only the diseased corneal layers whilst retaining unaffected layers represents a new paradigm shift in the field. Recent advancements in surgical techniques and instrumentation have resulted in several forms of manual, microkeratome and femto-second laser-assisted lamellar transplantation procedures. Anterior lamellar keratoplasty (ALK) aims at replacing only diseased or scarred corneal stroma, whilst retaining the unaffected corneal endothelial layer, thus obviating the risk of endothelial allograft rejection. Posterior lamellar keratoplasty/endothelial keratoplasty (PLK/EK) involves the replacement of the dysfunctional endothelial cell layer only. Whilst significant technical and surgical challenges are involved in performing lamellar micro-dissection of a tissue which is only 0.5 mm thick, the benefits of a more controlled surgical procedure and improved graft survival rates have resulted in a shift away from conventional PK. This review details the current advances in emerging lamellar corneal surgical procedures and highlights the main advantages and disadvantages of these new lamellar corneal procedures.

Corneal transplant surgery

Corneal disease is one of the major causes of blindness worldwide. Removal of the damaged cornea and transplant of donated tissue is often the only option available to patients to improve and restore vision. This paper discusses corneal transplant with consideration given to penetrating keratoplasty (PK), a traditional full thickness corneal transplant and three other surgical techniques that offer an alternative to the traditional PK surgery: deep anterior lamellar keratoplasty (DALK), deep lamellar endothelial keratoplasty (DLEK) and limbal stem cell transplant.

[Treatment strategy for rejection-free corneal transplantation--transition from full-thickness corneal transplantation to corneal endothelium transplantation]

The avoidance of allograft rejection is the most critical factor for favorable surgical outcome after corneal transplantation. We report experimental data including distribution of white blood cells in human corneas for rejection-free corneal transplantation. We focused on leukocyte trafficking based on the immunological mechanism leading to allograft rejection in a mouse full-thickness corneal transplantation model. We identified two chemokine-receptors, CCR1 and CCR7 which are functionally relevant to the occurrence of allograft rejection. These chemokine receptors can be new targets for the suppression of allograft rejection after full-thickness corneal transplantation. In the human corneas, bone marrow-derived dendritic cells and monocyte-lineage cells reside constitutively in the normal epithelium and stroma, and may be associated with direct recognition of allo-antigen after corneal transplantation. We established a mouse model in which cultured allocorneal endothelium was transplanted onto a bullous keratopathy recipient cornea. During the follow-up period, the transplanted cultured allo-corneal endothelium did not show any sign of allograft rejection. Our findings demonstrated that a rejection-free mechanism is due not to suppression of immunity or to lack of response, but to failure to recognize the existence of resistance. Realization of the clinical application of cultured allo-corneal endothelium transplantation may be a shortcut to ideal rejection-free corneal transplantation.

[Corneal transplantation in Romania]

The paper shows the activity of corneal transplantation in Romania. The author discuss about the aspects involved in this activity. The laws about donation, prelevation and surgery. Juridical aspects about activity of tissues banks. Human resources. Material resources. The author tries to find some solutions for improvement of this activity.

Future Directions in Lamellar Corneal Transplantation

The concept of lamellar keratoplasty (LK) is that of targeted lamellar replacement of corneal tissue while retaining normal cornea. It involves replacing either anterior stroma [anterior lamellar keratoplasty (ALK)] or posterior replacement of deep stromal and endothelial layers [posterior lamellar keratoplasty (PLK) or endothelial keratoplasty]. Despite the distinct advantages of ALK surgery, penetrating keratoplasty (PK) remains the most common procedure-largely because lamellar surgery is more technically demanding and time consuming, and interface irregularity arising from manual lamellar dissection often results in suboptimal visual outcomes. Recent improvements of surgical technique and advances in instrumentation such as microkeratome-assisted lamellar transplantation have contributed to improved visual quality with LK surgery. Long-term graft survival rates and endothelial cell counts after PK continue to drop for many years after surgery, clearly showing the disadvantage of unnecessary replacement of healthy endothelium in anterior-stromal disorders. The aim of this review is to evaluate the shifting emphasis from penetrating to lamellar forms of corneal transplantation and to highlight some future directions in lamellar surgery including new techniques in both ALK and PLK and the use of microkeratomes and femtosecond lasers to enhance outcomes.

Organ failure in Syria: initiating a national deceased donation program

In the absence of formal registry data, the volume and causes of organ failure in Syria are difficult to establish with certainty. However, we evaluated in this study the extent of organ failure by collecting data from health care authorities in different medical institutions who are involved in caring for patients with organ failure. Subsequently, we assessed the problem of the widening gap between organ supply and demand in our country and we highlighted the obstacles to initiating a national deceased donation program as a viable option to address the challenge of organ shortage. The estimated prevalence of corneal blindness in Syria is 2.3 per one thousand population. The estimated incidence of viral-induced cirrhosis is 49 - 67 per one million population (pmp); these include both HCV and HBV, which constitute the leading causes of liver failure. We estimated the incidence of end-stage renal disease (ESRD) to be from 80 - 100 pmp. Obstacles to initiating a national deceased donation program include lack of awareness of the public at large and health care professionals to the importance of organ donation and transplantation. Other obstacles include lack of adequate resources in terms of finance, personnel and services and the unavailability of a national center for organ transplantation that influences public attitude, sets national guidelines and supervises all activities related to organ donation and transplantation.

[Achievements of S. N. Fyodorov's school in the field of keratoplasty and cornea replacement]

Reduction in corneal transparence leading to the loss of sight may be caused by different factors, such as eye burns and injuries, keratitis, corneal ulcers, primary and secondary dystrophy, keratoconus, and keratoglobus. In many cases, keratoplasty presents an effective treatment. S. N. Fyodorov made a great contribution to the development of cornea replacement. This was him who placed the entire ophthalmology, including keratoplasty, at the microsurgical level, suggested the use of large-diameter grafts, and was the initiator of establishing the first Eye Tissue Bank. Perfection of microsurgical technique, selection and protection of the graft, as well as new approaches to pre- and postoperation therapy have provided transparent engrafting in 35 to 95%. Presently, Eye Microsurgery Complex is the only Russian institution where the problem of cornea replacement is being worked out as a scientific and practical issue. Three models of keratoprosthesis have been developed: Fyodorov-Zuyev model for implantation into a burn leukoma, Moroz-Glazko model for implantation into a dystrophic leukoma, and a "grid" for implantation into a leukoma of any etiology.

Lamelläre Keratoplastik

In 1840 Mühlbauer was the first to describe a technique for anterior lamellar keratoplasty (LKP). However, in the second half of the twentieth century penetrating keratoplasty (PKP) became the gold standard. Although it is associated with a higher risk for serious complications -- it is technically easier to perform and avoids wound healing reactions in the lamellar interface and thus resulting in better visual acuity. In view of the pathology, replacing all layers of the cornea including healthy parts can be considered therapeutic "overkill" for many corneal graft indications. Several innovative surgical techniques have recently been described which allow the lamellar dissection of recipient and donor cornea with good reproducibility in almost every desired depth. This now allows the recipient endothelium and Descemet's membrane to be selectively replaced or preserved and to avoid formation of an optical barrier in the lamellar interface in eyes undergoing lamellar keratoplasty for optical indications. The most important principal advantage of an anterior LKP -- to minimize the risk of an immune reaction in the graft -- is even more important in tectonic indications. From the large number of variations, the surgical technique, results, and problems with anterior and posterior LKP for optical indications as well as lamellar segment keratoplasty and epikeratoplasty for tectonic indications are discussed.

Changing indications for corneal transplantation at the King Khaled Eye Specialist Hospital (1983-2002)

PURPOSE

To identify changing indications for keratoplasty over the last 20 years at a tertiary care eye hospital in a country with rapidly evolving ophthalmic care services.

METHODS

A retrospective review was performed of the eye bank records of every patient who received a lamellar or penetrating keratoplasty at the King Khaled Eye Specialist Hospital in Riyadh, Saudi Arabia, between January 1, 1983 and December 31, 2002. For each case, the primary surgical indication was identified.

RESULTS

A total of 8318 corneal transplants were performed during this 20-year period. In the first 5 years of the study, the leading indications for corneal transplantation were corneal scarring (52.0%), aphakic/pseudophakic bullous keratopathy (13.5%), corneal degeneration (10.0%), and keratoconus (7.6%). During the last 5 years of the study, the leading indications for corneal transplantation were keratoconus (40.2%), corneal scarring (19.8%), failed corneal transplant (11.3%), and corneal ulceration (10.2%). There was a dramatic increase in the number of transplants performed for keratoconus (441%) and failed corneal transplants (285%) as well as a dramatic decrease in the number of transplants performed for corneal degeneration (-88%) and scarring (-60%) between the first and last 5 years of the study period.

CONCLUSIONS

Major changes in the indications for corneal transplantation were related to the introduction and expansion of modern ophthalmic services at a time of rapid socioeconomic development and population growth.

[The French national waiting list for keratoplasty created in 1999: patient registration, indications, characteristics, and turnover]

PURPOSE

To evaluate the French waiting list and the indications of registered patients, to compare the rates of registration, graft, and procurement between French regions.

METHODS

In France, each patient with an indication for penetrating keratoplasty should be registered on the waiting list with his or her clinical characteristics. Those registered during 2000 and 2001 were included in the study. Data on transplantation activity from the waiting list were compared to data collected by a questionnaire on graft and procurement activities completed each year by medical teams.

RESULTS

In 2000 and 2001, 6093 and 5505 waiting patients, respectively, were registered. For the same years, 3984 and 3457 keratoplasties were declared for the patients registered, but the questionnaires reported 4514 and 4388 grafts, respectively. The national registration rate was 96 per million population (pmp). The extreme values between regions ranged from 53 to 143 pmp. There was a significant correlation between regional procurement and transplantation rates (r=0.75, p=0.001) but not for registration and procurement rates, and not for registration and transplantation rates. The national registration rate was 27 pmp for pseudophakic and aphakic corneal edema, with extreme values of 12-64 pmp. The national registration rate was 24 pmp for keratoconus (11-37 pmp). A high patient turnover was observed between regions. Among the 11,598 patients registered, the most common indications were pseudophakic and aphakic corneal edema (27.7%), keratoconus (25.3%), and Fuchs'endothelial dystrophy (9.1%). Mean recipient age was 57+/-22 years (0-103 years). Among these patients, 14.1% had already received transplants at least once for the same eye (7.8% for keratoconus, 14.3% for pseudophakic and aphakic corneal edema, and 6.1% for Fuchs'dystrophy).

DISCUSSION

Ophthalmologists will be able to register their patients directly on the waiting list, which will improve data quality for transplantation notification. Regional policies should be developed to decrease the inequalities of graft shortages between regions.

Shortage in the face of plenty: improving the allocation of corneas for transplantation

BACKGROUND

As there are plenty of potential corneal donors, theoretically there should be no shortage of corneal grafts. Practically, however, shortages have been a problem, especially with HLA-matched corneas, which are increasingly requested. This increase requires evaluation and proper adaptation to meet all requests in the future.

METHODS

BIS' allocation data for corneal transplants were analyzed for the years 1998 through 2001.

RESULTS

Allocation of matched corneas almost doubled in 2000. The waiting list for matched grafts could be reduced by one third.

CONCLUSIONS

A steep increase in demand for matched grafts could be noted by the year 2000. This signifies that the results of positive matching studies have ultimately been taken notice of by the ophthalmic surgeons with consequent adaptation of their graft orders. BIS has mostly been able to cope with these rapidly changing and increasing demands, but more efforts are continuously needed to supply those typed and matched corneas within short time. Our next step will be to offer HLA-DR matching routinely in addition to the current HLA-A/-B matching. We are looking forward with great interest to the introduction of even more specified matching algorithms in the not too far distant future, and are prepared to meet all the requirements which might be associated with such challenges.

[Growing waiting list for corneal transplantation]

New corneal storage techniques and legislative changes have transformed conditions for corneal grafting in Sweden. Since 1995, the Swedish Corneal Surgery Society has registered the number of grafts, the size of waiting lists for surgery as well as changes in the capacity of the banks. Since 1995 the number of procedures per year has declined while the waiting list has grown. The required number of procedures is 650 rather than the 448 performed in 1999. The decline is due to a lack of donor corneas, priority accorded to other surgery, efforts to adapt contact lenses to keratoconus, and further indications for excimer laser surgery. The four established corneal banks as well as two opening in 2001 will increase the number of grafts available for surgery.

A review of the development of a synthetic corneal onlay for refractive correction

A synthetic corneal onlay, or implantable contact lens, could obviate the need for spectacles or conventional contact lenses in patients who seek convenient, reversible correction of refractive error. Several research groups have attempted to develop such a product in the past but much of the data from these studies remains unpublished due to commercial interests. This article reviews relevant papers and patents in the corneal implant field and discusses our efforts to develop a synthetic corneal onlay using a perfluoropolyether-based polymer.

Recent developments in cornea transplantation (1997-1999)

Between 1997 and 1999 a steady increase in cornea donations was achieved, but the number of transplantations remained stable because many grafts did not pass quality control. Intermediate organ culture of entire bulbi was examined as a possible solution to reduce post-mortem times and increase suitability for transplantation.

The management of corneal trauma: advances in the past twenty-five years

Over the past quarter century, advances in our understanding of corneal anatomy, physiology, and wound healing have all played an integral role in the management of corneal trauma. As the etiologies of corneal trauma have changed, so has our understanding of the impact of injury on corneal function as it relates to visual rehabilitation. Numerous new classes of antibiotics, antiinflammatory agents, and tissue adhesives have emerged. Occlusive therapy has advanced from simple pressure patching bandage soft contact lenses and collagen shields. Surgical instrumentation, operating microscopes, viscoelastic substances, and suture materials have all improved the outcomes of corneal trauma repair. Improved understanding of the refractive properties of the cornea through topography and alternative suture techniques has helped us restore the natural corneal curvature and visual outcomes. Consequently, in the last quarter of this century our therapeutic approaches to cornea trauma, both medical and surgical, have improved.

The future of lamellar keratoplasty

New surgical techniques in lamellar keratoplasty, including phototherapeutic keratectomy, automated lamellar keratectomy, plano-epikeratoplasty, deep anterior lamellar keratoplasty, combined amniotic membrane and limbal transplantation, large-diameter corneoscleral lamellar keratoplasty, and posterior lamellar keratoplasty, have recently become available. These procedures broaden the array of treatments for corneal disorders and may be used as alternatives to penetrating keratoplasty.

Current trends in cataract and refractive surgery in Japan: 1997 survey

PURPOSE

A sixth annual survey was carried out by mail in January 1998, to investigate the current trends in cataract and refractive surgery in Japan.

RESPONDENTS

Questionnaires were sent to 816 ophthalmologist members of the Japanese Society of Cataract and Refractive Surgery. Data received from 409 (50.1%) of the recipients were cross-analyzed and compared with those from the previous surveys.

RESULTS AND CONCLUSION

In cataract surgery, there have been trends toward more surgical procedures performed by a surgeon, shorter period of hospitalization, and increased number of outpatient surgery. Ninety-two percent of respondents preferred phacoemulsification, 54% used the self-sealing wound-closure technique, and 19% used topical anesthesia for phacoemulsification. As for refractive surgery, surgeons remained rather conservative; with 28% and 7% of surgeons doing astigmatic keratotomy and refractive keratotomy, respectively. Photorefractive keratectomy, laser in situ keratomileusis, and phakic intraocular lens were judged to be useful refractive surgical procedures by 56.6%, 43.3%, and 25.1% of the respondents, respectively.