Treatment Of Corneal Endothelial Diseases Research Articles

Corneal Donor Tissue Preparation for Endothelial Keratoplasty

Over the past ten years, corneal transplantation surgical techniques have undergone revolutionary changes1,2. Since its inception, traditional full thickness corneal transplantation has been the treatment to restore sight in those limited by corneal disease. Some disadvantages to this approach include a high degree of post-operative astigmatism, lack of predictable refractive outcome, and disturbance to the ocular surface. The development of Descemet's stripping endothelial keratoplasty (DSEK), transplanting only the posterior corneal stroma, Descemet's membrane, and endothelium, has dramatically changed treatment of corneal endothelial disease. DSEK is performed through a smaller incision; this technique avoids 'open sky' surgery with its risk of hemorrhage or expulsion, decreases the incidence of postoperative wound dehiscence, reduces unpredictable refractive outcomes, and may decrease the rate of transplant rejection3-6. Initially, cornea donor posterior lamellar dissection for DSEK was performed manually1 resulting in variable graft thickness and damage to the delicate corneal endothelial tissue during tissue processing. Automated lamellar dissection (Descemet's stripping automated endothelial keratoplasty, DSAEK) was developed to address these issues. Automated dissection utilizes the same technology as LASIK corneal flap creation with a mechanical microkeratome blade that helps to create uniform and thin tissue grafts for DSAEK surgery with minimal corneal endothelial cell loss in tissue processing. Eye banks have been providing full thickness corneas for surgical transplantation for many years. In 2006, eye banks began to develop methodologies for supplying precut corneal tissue for endothelial keratoplasty. With the input of corneal surgeons, eye banks have developed thorough protocols to safely and effectively prepare posterior lamellar tissue for DSAEK surgery. This can be performed preoperatively at the eye bank. Research shows no significant difference in terms of the quality of the tissue7 or patient outcomes8,9 using eye bank precut tissue versus surgeon-prepared tissue for DSAEK surgery. For most corneal surgeons, the availability of precut DSAEK corneal tissue saves time and money10, and reduces the stress of performing the donor corneal dissection in the operating room. In part because of the ability of the eye banks to provide high quality posterior lamellar corneal in a timely manner, DSAEK has become the standard of care for surgical management of corneal endothelial disease. The procedure that we are describing is the preparation of the posterior lamellar cornea at the eye bank for transplantation in DSAEK surgery (Figure 1).

Descemetorrhexis in endothelial keratoplasty to avoid peripheral bullous keratopathy

Descemet-stripping automated endothelial keratoplasty has revolutionized the treatment of corneal endothelial disease. This procedure requires the removal of the Descemet membrane (DM) and the endothelium from the recipient cornea.We describe a simple technique to perform descemetorrhexis using an ophthalmic viscosurgical device to fill the anterior chamber and using capsulorrhexis forceps to create a controlled, continuous curvilinear DM tear in 19 cases. Avoidance of tearing the DM out to the periphery reduces endothelial cell loss, decreases migration of central endothelium to deficient areas, and minimizes the risk for chronic corneal edema and peripheral bullous keratopathy.

Descemet’s stripping automated endothelial keratoplasty: past, present and future

Descemet’s stripping automated endothelial keratoplasty (DSAEK) is the gold standard for the surgical treatment of corneal endothelial diseases. Following its introduction over the last decade, DSAEK has evolved, showing excellent results in a variety of pathologies; for example, Fuchs’ endothelial dystrophy, pseudophakic bullous keratopathy, endothelial failure after penetrating keratoplasty or iridocorneal endothelial syndrome. Since it involves the use of a small incision that replaces only the affected part of the cornea, one of the advantages of this procedure is the rapid visual recovery compared with penetrating keratoplasty. DSAEK also poses major technical challenges to corneal surgeons and novel improvements are under the scope of researchers, such as the use of cultivated human corneal endothelial cells and the development of specific inserter devices to insert the endothelial graft. Owing to this innovation in endothelial keratoplasty surgery, a new chapter in the long history and evolution of corneal transplantation is upon us.

Economic impact of the advent of posterior lamellar keratoplasty in Montreal, Quebec

Objective: To assess the cost-utility of posterior lamellar keratoplasty (PLK) techniques, including deep lamellar endothelial keratoplasty, Descemet stripping endothelial keratoplasty, and Descemet stripping automated endothelial keratoplasty, in the treatment of corneal endothelial diseases. Design: Cost-utility analysis based on a Markov model. Participants: Cohort of 100 patients waiting for corneal graft. Methods: This cost-utility analysis was performed from a Canadian health system perspective over a lifetime period. A Markov model was constructed to compare the cost per quality-adjusted life-year (QALY) associated with penetrating keratoplasty (PK) and PLK techniques. The model included all major health states relevant to patients scheduled for corneal transplant: waiting for transplant, surviving graft with or without complications, irreversible failure, noneligibility, and death. Transition probabilities among health states were obtained from published clinical trials. Costs considered were those associated with surgery, patients’ follow-up, and postsurgical complications. Number of QALYs was estimated presurgery and postsurgery using the Brown and Sharma conversion chart. Results: PLK proved to be more effective, providing more QALYs (+13 QALYs/100 patients), and it was less costly (−$68 792/100 patients) compared with PK. Deterministic and probabilistic sensitivity analyses confirmed the robustness of the base-case results. Conclusion: From a clinical and an economic standpoint, PLK in the management of patients waiting for corneal graft represents a preferred strategy compared with PK only.

Endothelial keratoplasty: From DLEK to DMEK

The last decade has heralded a revolutionary shift in the treatment of corneal endothelial disease. Only 15 years ago, the only surgical treatment for pseudophakic bullous keratopathy and Fuchs dystrophy was penetrating keratoplasty (PK). Although used successfully for over a century, PK requires many months of refractive adjustments before the eye achieves visual stability. Starting with the advent of posterior lamellar keratoplasty in the late 1990s, a number of procedures have been developed, refined, and widely adopted, which have given patients faster recoveries and improved globe stability in comparison to traditional corneal transplantation. Each iteration of endothelial keratoplasty (EK) has involved the increasingly selective transplantation of corneal endothelial cells. Preliminary results of the most recent form of EK, Descemet's membrane EK, suggest that pure endothelial cell transplantation is on the horizon.

Modified air-assisted descemetorhexis for Descemet-stripping automated endothelial keratoplasty

Descemet-stripping automated endothelial keratoplasty (DSAEK) is an alternative to penetrating keratoplasty for the treatment of corneal endothelial disease that involves stripping diseased Descemet membrane (DM) from the recipient. Descemet membrane stripping is currently performed with a generic balanced salt solution (BSS) or an ophthalmic viscosurgical device in the anterior chamber, but limitations of these techniques include poor visualization of DM and difficulty maneuvering loose DM. We describe a simple modified technique to perform descemetorhexis under air that improves visualization, even in cloudy corneas, and aids in control of DM because of the enhanced surface tension from the air-fluid interface on the posterior corneal surface.