Descemet Membrane Endothelial Keratoplasty With and Without Graft Deswelling: A Prospective Clinical Study.

PURPOSE: The purpose of this study was to assess whether omission of dextran from corneal organ culture medium alters the outcome of Descemet membrane endothelial keratoplasty. METHODS: Participation in this single-center, multisurgeon, prospective, randomized, comparative clinical trial was offered to patients scheduled for Descemet membrane endothelial keratoplasty between April 2020 and May 2022. Patients received grafts from corneas deswollen in organ culture medium-containing 6% dextran T-500 or from corneas that were not deswollen. Corrected distance visual acuity (CDVA), graft detachment, central corneal thickness (CCT), and corneal endothelial cell counts were measured at different time points up to 12 months postoperatively. RESULTS: Grafts stored with dextran were transplanted in 92 patients, and grafts stored without dextran were transplanted in 102 patients. Mean donor age and endothelial cell counts did not differ significantly between both groups. Mean (±SD) postmortem time in hours was 23.9 ± 11.8 in grafts that were deswollen and 28.2 ± 13.8 in grafts that were not deswollen (P = 0.02). The groups did not show any significant difference at baseline regarding sex, CDVA, or CCT. In the group with dextran, patients had a mean age of 72.5 ± 9.9 years versus 69.5 ± 8.7 in the group without dextran (P = 0.03). CDVA improved and CCT decreased significantly in both groups. No differences were detected between the groups regarding CDVA, CCT, endothelial cell counts, or rebubbling rates. CONCLUSIONS: This study did not detect any evidence that the omission of dextran from organ culture medium negatively affects the outcomes of Descemet membrane endothelial keratoplasty.

Indications and outcomes of keratoplasty ≤ 5.5 mm diameter ("mini-keratoplasty").

PURPOSE: To report indications and clinical outcomes of corneal grafts ≤ 5.5 mm in diameter ("mini-KP") in a German tertiary referral center. METHODS: Patients who had undergone mini-KP to treat corneal ulcers with or without perforation between 2011 and 2018 at the Department of Ophthalmology, University of Düsseldorf, Germany, were identified from the local keratoplasty registry. All patient records were reviewed for age, gender, laterality, systemic and ophthalmological diseases, etiology of the corneal ulcerative disease, pre- and postoperative visual acuity over a follow-up time of up to 12 months, graft size, postoperative complications and the need for and timing of further corneal interventions. RESULTS: 37 eyes of 37 patients (male: n = 20; female: n = 17) with a mean age (± standard deviation) at presentation of 70 ± 18.8 years (range: 22-92 years) were identified. Most common etiologies were neurotrophic keratopathy (n = 15), dysfunctional tear syndrome (n = 9) and atopic keratoconjunctivitis (9). Mean graft diameter was 4.51 ± 0.63 mm (range: 3-5.5 mm). 23/37 eyes (62%) required no further intervention in the acute phase. 14/37 patients (38%) required secondary corneal intervention, due to complications. One-year graft survival was 78.4%. One eye had to be eviscerated due to recurrent corneal ulceration and endophthalmitis. 36 of 37 eyes were preserved. We found a highly significant correlation between type 2 diabetes and the development of postoperative complications (r = .46; p = .005). Corrected distance visual acuity (CDVA) improved from 1.42 ± 0.75 logMAR to 0.9 ± 0.65 logMAR postoperatively (t (23) = 5.76; p < .001). CONCLUSION: Mini-KP can be used successfully in eyes with advanced corneal ulcers due to various infectious and noninfectious etiologies to restore tectonic stability in the long-term and with moderate visual gains.

Evaluation of the Use of Intraoperative OCT in Routine Surgery: A Two-year Comparison. / Evaluation der Nutzung von intraoperativer OCT im operativen Alltag: ein 2-Jahres-Vergleich.

BACKGROUND: In recent years, an increasing number of surgical microscopes fitted with an OCT module (intraoperative OCT, iOCT) have become available, providing high-resolution images of the surgical site in real time. While a 2018 survey at our hospital showed that iOCT delivered an additional intraoperative benefit in only 2.4% of all operations, considering that the manufacturer had since revised the hardware and software, we conducted a second user evaluation of this technology. MATERIAL AND METHODS: Prospective monocentric analysis of the application and user-friendliness of an EnFocus Ultra-Deep OCT (Leica Microsystems) over a period of 25 (2018) and 20 working days (2021). A standardized questionnaire was used to assess the surgeons' use of iOCT and its influence on the surgical course. RESULTS: 118 operations were performed over a 25-day period in 2018 and 92 operations were performed over a 20-day period in 2021. In 2018, iOCT was used in 24.6% and in 2021 in 48.9% of all surgeries, with iOCT proving to be "critical" to the surgical course in 2.4% and 3.3% of cases, respectively, as assessed by the surgeons in both years. These were operations in which the intraocular view was limited, e.g., with decompensated cornea, vitreous hemorrhage, or after previous surgery, e.g., after penetrating keratoplasty. CONCLUSION: Further development of the user interface led to an improvement in usability, and the iOCT was used significantly more often. In both years, the iOCT proved to be critical for the course of the surgery in a comparably small number of operations, especially those involving complex situations.

Innovations in Corneal Crosslinking.

PURPOSE: Corneal Crosslinking (CXL) strengthens the keratoconus cornea and prevents further disease progression. Modified crosslinking protocols and different riboflavin solutions have been proposed to optimize the procedure and improve treatment success. METHODS: PubMed research of relevant publications and report of own experiences with different CXL protocols. RESULTS: Accelerated CXL shows comparable efficiency with shorter surgery time and similar complication rates. Customized CXL provides improved results with faster epithelial healing. CXL in a hyperoxic environment seems to be a safe and effective transepithelial alternative with presumably less complications and fewer side effects. Thin corneas (<400 µm) can be treated safely by corneal swelling using hypoosmolar riboflavin solutions and reducing the applied UV-energy. The combination of CXL with photorefractive keratectomy (PRK) can be considered in patients with contact lens intolerance improving visual acuity, however, with increased risk of visual loss compared to CXL alone. Two-Photon (2Ph) CXL is a promising new technology enabling three-dimensional CXL. DISCUSSION: Recently developed CXL protocols offer advantages over the standard "Dresden-protocol" and should be considered in patients with progressive keratectasia.

Acute corneal melt and perforation - A possible complication after riboflavin/UV-A crosslinking (CXL) in keratoconus.

Purpose: To report two cases of acute corneal melting and perforation requiring emergency penetrating keratoplasty after corneal crosslinking (CXL) in advanced keratoconus. Observations: Case 1 was a 34 and case 2 was a 16-year old male, both with progressive keratoconus, who underwent CXL (Dresden protocol). After riboflavin imbibition, patients had a minimal pachymetry of 337 µm and 347 µm, and therefore required stromal swelling by hypoosmolar riboflavin resulting in pachymetries of 470 µm and 422 µm, prior to the 30 minute UV-irradiation with 3mW/cm2. In case 1, on the 7th postoperative day a 4mm linear perforation occurred. Extensive post-hoc examinations revealed no infectious cause. In case 2, a corneal melting developed within 24 hours, from which Staphylococcus aureus was cultured. Conclusions and importance: Acute corneal melting and perforation may occur after CXL. Dysfunctional collagen metabolism, atopia, thin preoperative pachymetry and the use of hypoosmolar substances may have initiated this complication in our cases.

Microbiological Testing of Split-Cornea Transplantation.

PURPOSE: By splitting a donor cornea into an anterior and a posterior donor lamella, the need for donor tissue can be reduced in times of lack of donors. Current eye bank regulations limit the use of each donor cornea to one recipient. METHODS: The anterior lamella not applied to the patient after each sterile DMEK preparation performed was stored for one week and was microbiologically controlled on day 7. RESULTS: Between October 2020 and December 2021, microbiological controls of 108 consecutive anterior lamellae were performed at the Department of Ophthalmology, University of Duesseldorf, without any contamination found. CONCLUSION: Our data suggest split-cornea transplantation is a microbiologically safe procedure.

[Conjunctival reconstruction-State of the art of regenerative treatment forms beyond the limbus]. / Bindehautrekonstruktion ­ Status quo regenerativer Therapieformen jenseits des Limbus.

BACKGROUND: The demands on conjunctival replacement tissues are high: they need to be elastic, clinically compatible, surgically feasible and support goblet cell growth. OBJECTIVE: This article provides an overview of currently applied conjunctival replacement tissues and those under investigation. METHOD: Current publications on clinically applied conjunctival replacement tissues and substrates which are the subject of scientific research and those already tested in animal models are presented and discussed. RESULTS: Replacement tissues in clinical use are autologous and allogenic conjunctiva, nasal and oral mucous membranes, amniotic membrane and decellularized tissues. Autologous conjunctiva shows good results but is not suitable for large defects due to limited availability. In these cases autologous nasal and oral mucous membranes can be used; however, success is limited in cases of autoimmune diseases. Amniotic membranes are frequently applied clinically but goblet cell growth is limited. Different decellularized tissues are used clinically and goblet cell growth was found in vivo. Robust comparative studies are not yet available. Biological matrices such as fibrin, collagen, elastin, gelatin or hyaluronate and synthetic tissues from the group of polyesters are being investigated in the laboratory and in animal models. These studies show good epithelialization and goblet cell growth in vivo. CONCLUSION: Transplantation of conjunctiva, nasal and oral mucous membranes and amniotic membranes show satisfactory clinical results but exhibit individual weaknesses. Further studies in animal models and clinical settings are required to further evaluate the benefits of other matrices, such as cell-free tissues or other biological and synthetic matrices.

[Regenerative medicine for the corneal epithelium : Cell therapy from bench to bedside]. / Regenerative Medizin für das Hornhautepithel : Zelltherapie in Wissenschaft und Klinik.

In the case of thermal or caustic burns of the ocular surface, loss of limbal epithelial stem cells leads to compromised self-renewal of the corneal epithelium. This results in permanent loss of vision. In these situations, transplantation of cultured limbal epithelial cells on an amniotic membrane or fibrin gel as substrate (Holoclar®) can help to regenerate the corneal surface. The required cells are obtained from the healthy partner eye, if available. Adult stem cells from other parts of the body potentially serve as alternative cell sources: hair follicles, oral mucosa, mesenchymal stromal cells, or induced pluripotent stem cells (originally, e.g., skin fibroblasts). The reprogramming of such cells can be achieved with the help of transcription factors. In addition, work is being done on biosynthetic or synthetic matrices, which not only serve as substrate material for the transplantation but also support the functional properties of these cells (self-renewal, corneal epithelial-typical phenotype).

Descemet Stripping without Transplantation in Fuchs Endothelial Corneal Dystrophy. / Descemet-Stripping ohne Transplantat bei Fuchsʼscher endothelialer Hornhautdystrophie?

Traditionally, corneal endothelium is considered post-mitotic, which means that spontaneous regeneration after loss of endothelial cells (e.g., in the context of Fuchs endothelial corneal dystrophy) is not expected. Nevertheless, it has been observed in several cases that an edematous cornea can clear after removal of a smaller area of Descemet's membrane. The posterior aspect of this area becomes covered again by corneal endothelial cells. This has resulted in a new surgical approach that does not involve a posterior lamellar graft: "Descemet stripping only". At the same time, data from in vitro experiments suggest that Rho kinase inhibitors (ROCK inhibitors) are pharmacological agents that promote proliferation and migration of corneal endothelium, and thus have a positive influence on healing.

RT-PCR Testing of Organ Culture Medium for Corneal Storage Fails to Detect SARS-CoV-2 Infection Due to Lack of Viral Replication.

Concerns of possible transmission of SARS-CoV-2 from donors to patients by corneal transplantation have caused a decline in corneal transplantations. Graft culture media are routinely tested for infectious risks, but it is unclear whether this constitutes a viable means to avoid transmitting SARS-CoV-2 via keratoplasty. We found that SARS-CoV-2 RNA was not present in the medium after seven days of organ culture of corneas from donors (n = 4), who were SARS-CoV-2-positive upon tissue procurement. These medium samples showed no presence of viral RNA. To pursue this question under controlled conditions and further exclude the possibility of productive infection in corneal grafts, we inoculated corneoscleral discs from healthy donors (n = 8) with infectious SARS-CoV-2 and performed PCR testing of the culture medium at various time points. After seven days of culture, we also tested for SARS-CoV-2 RNA within the inoculated corneal tissue. The medium from tissue samples inoculated with SARS-CoV-2 showed no increase in viral RNA, which may indicate lack of viral replication in these corneal grafts. SARS-CoV-2-RNA was, however, detected on or in corneal tissue seven days after inoculation. Our data suggest that corneal grafts may not be permissive for replication of SARS-CoV-2 and demonstrates that PCR testing of culture media cannot safely exclude that tissue has been exposed to SARS-CoV-2. It also demonstrates the difficulty to differentiate between virus adherence and virus replication by PCR testing in SARS-CoV-2 exposed tissue.

Cryopreservation in a Standard Freezer: -28 °C as Alternative Storage Temperature for Amniotic Membrane Transplantation.

Human amniotic membrane (hAM) is usually stored at -80 °C. However, in many regions, cryopreservation at -80 °C is not feasible, making hAM unavailable. Therefore, the possibility of cryopreservation at -28 °C (household freezer) was investigated. hAMs (n = 8) were stored at -80 °C or -28 °C for a mean time of 8.2 months. hAM thickness, epithelial integrity and basement membrane were assessed histologically. The collagen content, concentration of hepatocyte growth factor (HGF) and basic fibroblast growth factor (bFGF) were determined. Elastic modulus and tensile strength were measured. The mean thickness of hAM stored at -28 °C was 33.1 ± 21.6 µm (range 9.7-74.9); thickness at -80 °C was 30.8 ± 14.7 µm (range 13.1-50.7; p = 0.72). Mean collagen content, epithelial cell number and integrity score showed no significant difference between samples stored at -28 °C or -80 °C. Basement membrane proteins were well preserved in both groups. Mean tensile strength and elastic modulus were not significantly different. Concentration of bFGF at -28 °C was 1063.2 ± 680.3 pg/g (range 369.2-2534.2), and 1312.1 ± 778.2 pg/g (range 496.2-2442.7) at -80 °C (p = 0.11). HGF was 5322.0 ± 2729.3 pg/g (range 603.3-9149.8) at -28 °C, and 11338.5 ± 6121.8 pg/g (range 4143.5 to 19806.7) at -80 °C (p = 0.02). No microbiological contamination was detected in any sample. The cryopreservation of hAM at -28 °C has no overt disadvantages compared to -80 °C; the essential characteristics of hAM are preserved. This temperature could be used in an alternative storage method whenever storage at -80 °C is unavailable.

[Treatment indications for corneal crosslinking and clinical results of new corneal crosslinking techniques]. / Indikationsstellung zum Crosslinking und klinische Ergebnisse neuer kornealer Crosslinking-Techniken.

BACKGROUND: Corneal crosslinking (CXL) is used in keratoconus to strengthen and stabilize the cornea and to prevent further progression with subsequent visual loss and the possible need for keratoplasty. Correct treatment indications is crucial in this context. Since the introduction of the initial Dresden protocol, other modified CXL protocols have been proposed to optimize treatment success. OBJECTIVE: The relevant parameters for treatment indications are explained and the clinical results of new CXL protocols are presented. METHODS: The currently valid criteria with respect to the indications for CXL in keratoconus, PubMed search for relevant publications and own experiences with different CXL protocols are presented. RESULTS: The reproducibility of topographic parameters depends on the stage of the keratoconus. Accelerated CXL as well as transepithelial CXL with a hyperoxic environment show comparable efficiency with shorter surgery time and possibly lower complication rates. Customized CXL with an individualized UV irradiation profile provides improved results with faster epithelial healing. Lower UV energy doses enable CXL to be conducted in eyes with minimal stromal pachymetry of less than 400 µm before irradiation. The combination of CXL with photorefractive keratectomy (PRK) provides visual acuity improvements but also increases the risk of visual loss. CONCLUSION: Current indication rules for CXL neglect the reduced reproducability of topographic and tomographic measurements in keratoconus. The latest CXL protocols presented here provide a safe alternative with similar and/or better efficacy compared to standard CXL. The combination of CXL with PRK offers an option for visual rehabilitation in patients with contact lens intolerance.

Current Challenges Facing Cornea Banks. / Aktuelle Herausforderungen der Hornhautbanken.

Cornea transplants are tissue transplants and, as such, must be distinguished from organ transplants (e.g. heart or kidney transplants). However, tissue transplants can only be performed if there are enough donors available to attend to patients in need. Unfortunately, there are too few organ and tissue donors in Germany. All steps involved in processing donor tissues must be performed in accordance with the highest quality standards. All tasks and measures are aimed at improving patient care in the surgical units that are to be supplied. Cornea banks are subject to complex requirements, whose implementation is essential in terms of both infrastructure and personnel. The analysis and identification of essential topics reveal central fields of action that are decisive for implementing the challenges facing cornea banks. Questions of employee qualification, strategic questions due to new transplantation techniques, and changes in the societal perception of organ and tissue donation require the development of strategies that should have a holistic and sustainable effect.

Eye Banks: Future Perspectives. / Hornhautbanken: Perspektiven für die Zukunft.

Technological progress and societal change are transforming medicine, and cornea banks are no exception. New infectiological factors, statutory requirements, management concepts, globalisation and digitalisation are also influencing how such facilities will operate in the future. The goal of providing high quality material to patients with corneal disease remains unaltered. The present article seeks to shed light on the type of material this will involve and under what circumstances it is to be obtained.

Wound Healing of Descemet Membrane After Penetrating Keratoplasty and Its Relevance for Descemet Membrane Endothelial Keratoplasty Surgeons.

ABSTRACT: Compared with penetrating keratoplasty (PK), Descemet membrane endothelial keratoplasty (DMEK) is characterized as lower risk for complications such as immunological graft reaction and faster and better postoperative visual recovery. In patients with endothelial graft failure after PK, DMEK can be used to regenerate PK graft transparency. The surgical technique for DMEK in this specific situation is still under debate, particularly regarding stripping of Descemet membrane (DM) from the failed PK and diameter of the DMEK graft. Here we report a case of a 75-year-old female patient with a failed graft 16 years after PK for Fuchs endothelial dystrophy, who underwent uneventful DMEK surgery. Stripping of DM in this particular case was performed outside the failed PK and demonstrated a biomechanically stable junction between the PK donor and the host DM. Histopathologic analysis of the excised DM showed continuous extracellular matrix connecting the host and donor DM, indicating primary intention wound healing after PK at this tissue level. This case demonstrates that after PK, a biomechanically stable and histologically continuous DM can enable Descemetorhexis outside the failed graft and transplantation of a DMEK graft larger than the previous PK. This may provide more endothelial cells for transplantation.

SARS-CoV-2: Impact on, Risk Assessment and Countermeasures in German Eye Banks.

INTRODUCTION: Since the beginning of the COVID-19 pandemic there has been some debate regarding the risk of transmission through tissue transplantation and tissue banking processes. AIM OF THE STUDY: To analyze the changes that SARS-CoV-2 has caused regarding the harvesting of corneal donor tissue and eye bank activities in Germany. METHODS: A questionnaire was provided to 26 eye banks in Germany, consisting of questions about adaptations made in the screening of potential donors and the harvesting of corneal tissue following the pandemic spread of SARS-CoV-2. RESULTS: Eighteen eye banks actively reduced recruitment of donors and two banks ceased all activity. Additional diagnostic screening was performed in eight banks, using conjunctival swabs and/or nasopharyngeal swabs. In six eye banks, additional protective measures, such as FFP2 masks and/or facial shields, were implemented. Overall, a mean reduction in the number of obtained donor tissues of 17% was observed. DISCUSSION: Conjunctival and/or nasopharyngeal swabs of donors have been implemented by a minority. Reasons for not performing additional tests may be moderate sensitivity and lack of validation for postmortem use of RT-PCR testing. Also, the hazard of SARS-CoV-2 entering the corneal donor pool with subsequent transmission might be perceived as theoretical. Face shields provide a sufficient barrier against splash and splatter contamination but may be insufficient against aerosols. Additional face masks would provide support against aerosols, but it remains debatable if corneal harvesting can be considered an aerosol-producing procedure. In the future we expect to see changes in current guidelines because of a surge in scientific activities to improve our understanding of the risks involved with cornea donation in the COVID-19 pandemic, and because current practice may reduce the availability of donor corneas due to new exclusion criteria while the demand remains unchanged.

Natural history of X-linked hypohidrotic ectodermal dysplasia: a 5-year follow-up study.

BACKGROUND: X-linked hypohidrotic ectodermal dysplasia (XLHED) is caused by pathogenic variants of the gene EDA disrupting the prenatal development of ectodermal derivatives. Cardinal symptoms are hypotrichosis, lack of teeth, and hypo- or anhidrosis, but the disease may also evoke other clinical problems. This study aimed at investigating the clinical course of XLHED in early childhood as the basis for an evaluation of the efficacy of potential treatments. METHODS: 25 children (19 boys and 6 girls between 11 and 35 months of age) with genetically confirmed XLHED were enrolled in a long-term natural history study. Clinical data were collected both retrospectively using parent questionnaires and medical records (pregnancy, birth, infancy) and prospectively until the age of 60 months. General development, dentition, sweating ability, ocular, respiratory, and skin involvement were assessed by standardized clinical examination and yearly quantitative surveys. RESULTS: All male subjects suffered from persistent anhidrosis and heat intolerance, although a few sweat ducts were detected in some patients. Sweating ability of girls with XLHED ranged from strongly reduced to almost normal. In the male subjects, 1-12 deciduous teeth erupted and 0-8 tooth germs of the permanent dentition became detectable. Tooth numbers were higher but variable in the female group. Most affected boys had no more than three if any Meibomian glands per eyelid, most girls had fewer than 10. Many male subjects developed additional, sometimes severe health issues, such as obstructive airway conditions, chronic eczema, or dry eye disease. Adverse events included various XLHED-related infections, unexplained fever, allergic reactions, and retardation of psychomotor development. CONCLUSIONS: This first comprehensive study of the course of XLHED confirmed the early involvement of multiple organs, pointing to the need of early therapeutic intervention.

Supplementation of organ culture medium with dextran is not required in pre-stripped human donor tissue for DMEK surgery.

To assess corneal endothelial cell (CEC) quantity and quality in eye-bank prepared lamellar grafts for Descemet Membrane Endothelial Keratoplasty (DMEK) from organ cultured donor corneas that have not undergone de-swelling by media supplementation with dextran. Prior to graft preparation, corneas that had not undergone de-swelling (n = 30) were placed into fresh storage medium without dextran (KMI). Corneas in the control group (n = 30) were placed in dehydration medium containing 5% dextran (KMII). Subtotal stripping of Descemet's membrane (DM) was performed manually. Following graft preparation, 10 corneas of each group were cultured further in their respective medium for 24 h, 72 h, or 120 h, respectively. Before and after DM stripping, as well as at the end of culture, CEC numbers were obtained. At the end of culture, CEC morphology was graded using a scoring system and CEC metabolism was assessed by detection of adenosine triphosphate. At 24 h after DM stripping, mean CEC counts (in cells/mm2) were 2204 in corneas stored in KMII, and 2391 in corneas stored in KMI (p = 0.003). This corresponds to a mean relative CEC loss of 12.4% with dextran versus 9.7% without dextran (p = 0.04). At 72 h, CEC counts were 1946 in KMII, and 2289 in KMI (p = 0.004). This corresponds to CEC loss of 23% with dextran versus 14% without dextran (p = 0.009). At 120 h, CEC counts were 2047 in KMII, and 2230 in KMI (p = 0.14). This corresponds to CEC loss of 22.7% with dextran versus 17.2% without dextran (p = 0.14). Also, at 120 h after DM stripping, 6/10 corneas fell below a threshold of 2000 cells/mm2 if stored in medium containing dextran, versus 1/9 corneas if stored without dextran (p = 0.003). Morphological assessment of CEC quality revealed equal scores for cell polymorphism (median = 1), granulation (median = 0) and segmentation (median = 1) in all groups. Lower ATP/protein ratios were observed in corneas stored in medium without dextran at 24 h (p < 0.001), 72 h (p < 0.001), and 120 h (p = 0.02). Abandoning the use of dextran in corneas destined for DMEK surgery leads to increased CEC counts and thereby serves to reduce tissue loss.