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Corneal transplantation, a pivotal intervention for various corneal disorders, involves replacing damaged or diseased corneal tissue with a healthy donor cornea. The goal of the procedure is to restore visual function, addressing conditions such as keratoconus, Fuchs endothelial dystrophy, and corneal scars. Techniques have evolved from full-thickness transplants to selective lamellar procedures like Descemet stripping endothelial keratoplasty (DSEK) and Descemet membrane endothelial keratoplasty (DMEK), enhancing outcomes and reducing complications. This continuing education activity thoroughly explores corneal transplantation, encompassing anatomy, historical context, indications, contraindications, surgical techniques, and recent advancements. Clinicians engaging with this activity will gain comprehensive insights into the evolving landscape of corneal transplantation. From understanding the historical progression to mastering modern techniques such as DSEK and DMEK, clinicians enhance their competence in patient assessment, surgical decision-making, and postoperative care. The activity emphasizes the importance of effective communication with patients and collaboration within a multidisciplinary healthcare team. Clinicians are equipped with the latest knowledge on advancements in immunology, tissue banking, and surgical approaches, ensuring they stay at the forefront to provide optimal care to patients undergoing corneal transplantation. Objectives: Identify potential candidates for corneal transplantation by conducting comprehensive evaluations, considering factors such as the nature of corneal disorders, patient history, and suitability for various transplantation techniques. Apply a comprehensive understanding of corneal anatomy, history, indications, contraindications, personnel, equipment, techniques, and complications to enhance decision-making and surgical proficiency. Assess postoperative outcomes and complications, monitoring patients for signs of rejection, infection, or other adverse events, and adjusting treatment plans accordingly. Collaborate with a multidisciplinary healthcare team, including ophthalmic surgeons, advanced practitioners, nurses, pharmacists, and other professionals, to ensure coordinated and patient-centered care throughout the transplantation process. Access free multiple choice questions on this topic.

Corneal disease is the fifth leading cause of global blindness, necessitating interventions such as keratoplasty, the most prevalent and successful human transplantation.[1] The first successful transplant was completed in 1905.[1][2] Various dystrophic, infectious, degenerative, and inflammatory corneal disorders, often secondary to ocular surface diseases, contribute to corneal blindness.[3] The widespread and intricate epidemiology involves infectious and nutritional disorders like trachoma, xerophthalmia, river blindness, and microbial keratitis, ranking second to cataracts in ocular conditions causing blindness globally. Developing countries, particularly in Africa and Asia, experience higher incidences, and corneal scarring remains a leading cause of reversible blindness in children.[4] Despite corneal transplantation being the primary visual rehabilitation method, its efficacy is constrained by limited expertise and donor corneal tissue availability, particularly in these developing nations.[5] In the Western world, inherited, degenerative, and iatrogenic conditions like Fuchs corneal endothelial dystrophy, keratoconus, and pseudophakic bullous keratopathy (PBK) are more prevalent, with a favorable prognosis. Corneal transplantation, a globally widespread procedure, addresses diverse indications such as keratoconus, PBK, corneal scars, dystrophies, and microbial keratitis.[6] However, in developing nations, the demand for treatment often outstrips the available supply. A previous article reported that in 2010, the number of corneal transplants in the United States was 42,642; in 2008, there were 12,623 solid organ transplants.[7][8] In countries like India, where the incidence of microbial keratitis is high, there were 27,075 corneal transplants performed between April 2019 and March 2020. However, due to the COVID-19 pandemic, the number of transplants fell to 12,998 performed between April 2020 and March 2021, as per data from the Eye Bank Association of India. The demand for corneal grafts often exceeds the supply in most eye banks, especially in developing countries, resulting in long waiting periods. This activity provides a comprehensive understanding of corneal transplantation, covering anatomy, history, indications, contraindications, personnel, equipment, techniques, and complications, offering valuable insights for students and clinicians.[9]

In the Western world, inherited, degenerative, and iatrogenic conditions like Fuchs corneal endothelial dystrophy, keratoconus, and pseudophakic bullous keratopathy (PBK) are more prevalent, with a favorable prognosis. Corneal transplantation, a globally widespread procedure, addresses diverse indications such as keratoconus, PBK, corneal scars, dystrophies, and microbial keratitis.[6] However, in developing nations, the demand for treatment often outstrips the available supply. A previous article reported that in 2010, the number of corneal transplants in the United States was 42,642; in 2008, there were 12,623 solid organ transplants.[7][8] In countries like India, where the incidence of microbial keratitis is high, there were 27,075 corneal transplants performed between April 2019 and March 2020. However, due to the COVID-19 pandemic, the number of transplants fell to 12,998 performed between April 2020 and March 2021, as per data from the Eye Bank Association of India. The demand for corneal grafts often exceeds the supply in most eye banks, especially in developing countries, resulting in long waiting periods. This activity provides a comprehensive understanding of corneal transplantation, covering anatomy, history, indications, contraindications, personnel, equipment, techniques, and complications, offering valuable insights for students and clinicians.[9] History of Corneal Transplantation The history of corneal transplant traces its roots to 1800, but significant strides occurred in the past 2 decades with the introduction of lamellar transplantation techniques. The evolution of modern corneal transplantation results from centuries of ideas, experimentation with xenografts and allografts, and resilience.[10] As early as 1789, French surgeon Pellier de Quengsy proposed using a transparent material to replace an opaque cornea.[11] The first documented report of anterior lamellar corneal transplantation dates back to 1800. Karl Himley, in 1813, envisioned and experimented with xenografts, with his student Franz Reisinger attempting the first experimental xenograft transplantation in 1824, albeit without success.

The history of corneal transplant traces its roots to 1800, but significant strides occurred in the past 2 decades with the introduction of lamellar transplantation techniques. The evolution of modern corneal transplantation results from centuries of ideas, experimentation with xenografts and allografts, and resilience.[10] As early as 1789, French surgeon Pellier de Quengsy proposed using a transparent material to replace an opaque cornea.[11] The first documented report of anterior lamellar corneal transplantation dates back to 1800. Karl Himley, in 1813, envisioned and experimented with xenografts, with his student Franz Reisinger attempting the first experimental xenograft transplantation in 1824, albeit without success. In 1838, Richard Kissam achieved a milestone by performing the first therapeutic corneal xenograft using a porcine cornea. The first successful human allograft and penetrating keratoplasty (PKP), following anesthetics and antiseptic surgery developments, was performed by Eduard Zirm in December 1905 on a farm laborer with lime burns.[12][13] Lamellar corneal transplants emerged as a pivotal advancement, mitigating the risk of endothelial graft failure. The introduction of topical steroids and refined surgical techniques in PKP in 1950 set the gold standard for corneal transplantation. The era of lamellar transplantation began in 2005, revolutionizing keratoplasty techniques. Successful outcomes hinge on meticulous ocular environment preparation, addressing inflammatory factors, and comprehensive systemic control, especially in cases involving rheumatoid arthritis and systemic lupus erythematosus. Preoperative control of diabetes, hypertension, cardiac, respiratory, and renal disease is also mandatory in each case.[14] Recent Developments

In 1838, Richard Kissam achieved a milestone by performing the first therapeutic corneal xenograft using a porcine cornea. The first successful human allograft and penetrating keratoplasty (PKP), following anesthetics and antiseptic surgery developments, was performed by Eduard Zirm in December 1905 on a farm laborer with lime burns.[12][13] Lamellar corneal transplants emerged as a pivotal advancement, mitigating the risk of endothelial graft failure. The introduction of topical steroids and refined surgical techniques in PKP in 1950 set the gold standard for corneal transplantation. The era of lamellar transplantation began in 2005, revolutionizing keratoplasty techniques. Successful outcomes hinge on meticulous ocular environment preparation, addressing inflammatory factors, and comprehensive systemic control, especially in cases involving rheumatoid arthritis and systemic lupus erythematosus. Preoperative control of diabetes, hypertension, cardiac, respiratory, and renal disease is also mandatory in each case.[14] Recent Developments Advancements in immunology, surgical techniques, and tissue banking have greatly influenced the field of corneal transplantation.[15][16] Over the last 2 decades, significant developments in selective endothelial replacement techniques have led to notable changes in the field. Gerrit Melles introduced a posterior lamellar keratoplasty (PLK) that involved transplanting only a portion of the cornea. The procedure involved making an incision at the limbus and dissecting and replacing the endothelium, the Descemet membrane (DM), and the posterior stroma with a donor button consisting of the same corneal layers. The donor button was held in place by an air bubble.[17]

Advancements in immunology, surgical techniques, and tissue banking have greatly influenced the field of corneal transplantation.[15][16] Over the last 2 decades, significant developments in selective endothelial replacement techniques have led to notable changes in the field. Gerrit Melles introduced a posterior lamellar keratoplasty (PLK) that involved transplanting only a portion of the cornea. The procedure involved making an incision at the limbus and dissecting and replacing the endothelium, the Descemet membrane (DM), and the posterior stroma with a donor button consisting of the same corneal layers. The donor button was held in place by an air bubble.[17] Mark Terry made modifications to the PLK procedure in 2001. He used viscoelastic material instead of an air bubble and renamed deep lamellar endothelial keratoplasty (DLEK).[18] In 2004, Gerrit Melles modified the technique by removing only the host endothelium and DM, thus eliminating the need for stromal dissection. He replaced it with a donor button of the endothelium, DM, and stroma, creating Descemet stripping endothelial keratoplasty (DSEK). This technique was later automated using a microtome, resulting in Descemet stripping automated endothelial keratoplasty (DSAEK).[19][20][21] In 2006, the technique was further developed by transplanting only a donor button of endothelium and DM without the posterior stroma, creating DM endothelial keratoplasty (DMEK).[21] Minor modifications include automated posterior lamella dissection similar to DSEK or DM automated endothelial keratoplasty (DMAEK).[22]

Mark Terry made modifications to the PLK procedure in 2001. He used viscoelastic material instead of an air bubble and renamed deep lamellar endothelial keratoplasty (DLEK).[18] In 2004, Gerrit Melles modified the technique by removing only the host endothelium and DM, thus eliminating the need for stromal dissection. He replaced it with a donor button of the endothelium, DM, and stroma, creating Descemet stripping endothelial keratoplasty (DSEK). This technique was later automated using a microtome, resulting in Descemet stripping automated endothelial keratoplasty (DSAEK).[19][20][21] In 2006, the technique was further developed by transplanting only a donor button of endothelium and DM without the posterior stroma, creating DM endothelial keratoplasty (DMEK).[21] Minor modifications include automated posterior lamella dissection similar to DSEK or DM automated endothelial keratoplasty (DMAEK).[22] A selective keratoplasty technique related to the anterior cornea is the deep anterior lamellar keratoplasty (DALK), whereby a donor button replaces the epithelium, Bowman layer, and stroma.[23] This selective lamellar transplant involves replacing only the diseased layer of the cornea while retaining the healthy layers, resulting in better visual outcomes and reducing the complication rate. The cornea has 5 layers, and only the Bowman layer, stroma, DM, and endothelium can be replaced.[24] The corneal endothelial cells have poor regenerating capacity, and any loss of these cells due to trauma or disease can lead to corneal edema. In contrast, PKP transplants all 5 layers of the cornea. In the United States, endothelial transplant rates increased significantly from 5% in 2005 to 44.9% in 2010. In 2022, the number of PKPs, DSAEK, and DMEK was almost equal, around 15,000 each. Lamellar transplant is now preferred over PKP for various indications, such as keratoconus, Fuchs endothelial dystrophy, and PBK.[25]

Complications following surgery can be categorized into 2 types: early and late. Early complications can occur within days to weeks after the operation and include wound leakage, raised intraocular pressure, bleeding, and infection. Late complications, on the other hand, can occur months to years after the operation and may include: Corneal swelling Cataracts Graft failure Graft dislocation Graft rejection Pupillary block glaucoma Graft infection Graft infiltrates Endophthalmitis Panophthalmitis Epithelial ingrowth Double anterior chamber Eccentric graft Astigmatism DM detachment DM perforation Secondary glaucoma Lens expulsion Expulsive choroidal hemorrhage Recurrence of the original disease The reported 5-year and 15-year graft survival rates are approximately 70% and 50%, respectively.[59][60]

A multidisciplinary team comprising physicians, advanced practitioners, nurses, pharmacists, and other health professionals ensures comprehensive and patient-centered care in corneal transplantation. Physicians, particularly ophthalmic surgeons specializing in corneal procedures, bring their surgical expertise and decision-making skills to the forefront. Advanced practitioners, such as physician assistants or nurse practitioners, contribute by conducting pre- and postoperative assessments, collaborating closely with physicians, and providing valuable patient education. Nurses are integral to care coordination, preoperative preparations, postoperative monitoring, and patient follow-up. Pharmacists are crucial in medication management, ensuring optimal immunosuppression and postoperative care drug regimens. Effective interprofessional communication is paramount for seamless coordination among team members, facilitating the exchange of critical information for timely decision-making. Regular team meetings, case discussions, and shared electronic health records foster collaborative discussions. This collaborative approach enhances patient-centered care by addressing individual needs, improving patient outcomes through comprehensive care strategies, ensuring patient safety by minimizing medication errors and complications, and optimizing team performance through streamlined communication and coordination.

The nursing, allied health staff, and the interprofessional team play a key role in managing cases with corneal transplantation. The nurses help in recruiting the patients to the outpatient department, help in scraping patients with microbial keratitis, explain the procedure to the patients, the importance of each keratoplasty, how to procure and use antimicrobial medication, steroids, and adjuvant drugs, help in counseling, postoperative management and follow up of these cases.[66]

The nursing, allied health staff, and the interprofessional team help monitor these patients with visual acuity assessment, intraocular pressure, regular follow-up, whether correct medications are being used, postoperative visual acuity, and regular monitoring and follow-up.[67]