Next-Generation Sequencing of the Human Aqueous Humour Microbiome.

The microbiome of the ocular surface has been characterised, but only limited information is available on a possible silent intraocular microbial colonisation in normal eyes. Therefore, we performed next-generation sequencing (NGS) of 16S rDNA genes in the aqueous humour. The aqueous humour was sampled from three patients during cataract surgery. Air swabs, conjunctival swabs from patients as well as from healthy donors served as controls. Following DNA extraction, the V3 and V4 hypervariable regions of the 16S rDNA gene were amplified and sequenced followed by denoising. The resulting Amplicon Sequence Variants were matched to a subset of the Ribosomal Database Project 16S database. The deduced bacterial community was then statistically analysed. The DNA content in all samples was low (0-1.49 ng/µL) but sufficient for analysis. The main phyla in the samples were Acinetobacteria (48%), Proteobacteria (26%), Firmicutes (14%), Acidobacteria (8%), and Bacteroidetes (2%). Patients' conjunctival control samples and anterior chamber fluid showed similar patterns of bacterial species containing many waterborne species. Non-disinfected samples showed a different bacterial spectrum than the air swab samples. The data confirm the existence of an ocular surface microbiome. Meanwhile, a distinct intraocular microbiome was not discernible from the background, suggesting the absence of an intraocular microbiome in normal eyes.

Quality Control in the Corneal Bank with Artificial Intelligence: Comparison of a New Deep Learning-based Approach with Conventional Endothelial Cell Counting by the "Rhine-Tec Endothelial Analysis System". / Qualitätskontrolle in der Hornhautbank mit künstlicher Intelligenz: Vergleich eines neuen Deep-Learning-basierten Ansatzes mit der konventionellen Endothelzelldichtenbestimmung durch das "Rhine-Tec Endothelial Analysis System".

Endothelial cell density (ECD) is a crucial parameter for the release of corneal grafts for transplantation. The Lions Eye Bank of Baden-Württemberg uses the "Rhine-Tec Endothelial Analysis System" for ECD quantification, which is based on a fixed counting frame method considering only a small sample of 15 to 40 endothelial cells. The measurement result therefore depends on the frame placement and manual correction of the cells counted within the frame. To increase the sample size and create higher objectivity, we developed a new method based on "deep learning" that automatically detects all visible endothelial cells in the image. This study aims to compare this new method with the conventional Rhine-Tec system. 9375 archived phase-contrast microscopic images of consecutive grafts from the Lions Eye Bank were evaluated with the deep learning method and compared with the corresponding archived analyses of the Rhine-Tec system. Means, Bland-Altman and correlation analyses were compared. Comparable results were obtained for both methods. The mean difference between the Rhine-Tec system and the deep learning method was only - 23 cells/mm2 (95% confidence interval - 29 to - 17). There was a statistically significant positive correlation between the two methods, with a correlation coefficient of 0.748. What was striking in the Bland-Altman analysis were clustered deviations in the cell density range between 2000 and 2500 cells/mm2 - with higher values in the Rhine-Tec system. The comparable results for cell density measurement values underline the validity of the deep learning-based method. The deviations around the formal threshold for graft release of 2000 cells/mm2 are most likely explained by the higher objectivity of the deep learning method and the fact that measurement frames and manual corrections were specifically selected to reach the formal threshold of 2000 cells/mm2 when the full area endothelial quality was good. This full area assessment of the graft endothelium cannot currently be replaced by deep learning methods and remains the most important basis for graft release for keratoplasty.

Clinical Course of Different Types of Immune Reactions following Keratoplasty.

BACKGROUND: Immune-mediated corneal graft rejection (IR) is a leading cause of corneal graft failure. The endothelium, stroma, epithelium, or a combination can be affected. Little is known about the long-term outcomes of different types of IR. METHODS: We reviewed the medical records of all keratoplasties that had been performed at our eye centre between 2003 and 2016 (n = 3934) for any kind of IR that occurred between the surgery and 2019. All patients with a definite diagnosis of IR and sufficient clinical data were included in the analysis. IRs were grouped according to the affected part of the graft (endothelial, stromal, epithelial, and mixed). We analysed the dynamics of recovery and the clinical outcomes. RESULTS: We identified a total of 319 patients with IR. Twenty-seven of those were lost to follow-up and were excluded from further analysis. Of the IRs, 89% affected the endothelium. Endothelial IR resulted more frequently in a considerable loss of endothelial cell density than other forms of IR. Stromal IR showed a lower relapse rate and a better visual recovery than other types of IR and resulted less often in a failure of the graft. CONCLUSIONS: We herein report comprehensive data about the prognosis regarding functional recovery after different types of IR following keratoplasty. Our data underline that timely recognition and correct classification of IR are important because they determine the clinical course and prognosis.

Transcriptional Profiling Provides New Insights into Organ Culture-Induced Changes in Human Donor Corneas.

Corneal transplantation is one of the most common forms of tissue transplantation worldwide. Donor corneal tissue used in transplantation is provided by eye banks, which store the tissue in culture medium after procurement. To date, the effects of cell culture on human corneal tissue have not been fully elucidated. Using the 3' RNA sequencing method for massive analysis of cDNA ends (MACE), we show that cultivation of corneal tissue leads to significant changes in a variety of molecular processes in human corneal tissue that go well beyond aspects of previously known culture effects. Functionally grouped network analysis revealed nine major groups of biological processes that were affected by corneal organ culture, among them keratinization, hypoxia, and angiogenesis, with genes from each group being affected by culture time. A cell type deconvolution analysis revealed significant modulations of the corneal immune cell profile in a time dependent manner. The results suggest that current culture conditions should be further refined and that prolonged cultivation may be detrimental. Recently, we showed that MACE enables transcriptional profiling of formalin-fixed and paraffin-embedded (FFPE) conjunctival tissue with high accuracy even after more than 10 years of storage. Here we demonstrate that MACE provides comparable results for native and FFPE corneal tissue, confirming that the technology is suitable for transcriptome analysis of a wide range of archived diseased corneal samples stored in histological archives. Finally, our data underscore the feasibility of bioinformatics cell-type enrichment analysis in bulk RNA-seq data to profile immune cell composition in fixed and archived corneal tissue samples, for which RNA-seq analysis of individual cells is often not possible.

Survey of Rejection Prophylaxis Following Suture Removal in Penetrating Keratoplasty in Germany. / Umfrage zur Abstoßungsprophylaxe bei Fadenentfernung nach perforierender Keratoplastik in Deutschland.

BACKGROUND: Penetrating keratoplasty (PK) gets more and more reserved to cases of increasing complexity. In such cases, ocular comorbidities may limit graft survival following PK. A major cause for graft failure is endothelial graft rejection. Suture removal is a known risk factor for graft rejection. Nevertheless, there is no evidence-based regimen for rejection prophylaxis following suture removal. Therefore, a survey of rejection prophylaxis was conducted at 7 German keratoplasty centres. OBJECTIVE: The aim of the study was documentation of the variability of medicinal aftercare following suture removal in Germany. METHODS: Seven German keratoplasty centres with the highest numbers for PK were selected. The centres were sent a survey consisting of half-open questions. The centres performed a mean of 140 PK in 2018. The return rate was 100%. The findings were tabulated. RESULTS: All centres perform a double-running cross-stitch suture for standard PK, as well as a treatment for rejection prophylaxis with topical steroids after suture removal. There are differences in intensity (1 - 5 times daily) and tapering (2 - 20 weeks) of the topical steroids following suture removal. Two centres additionally use systemic steroids for a few days. DISCUSSION: Rejection prophylaxis following PK is currently poorly standardised and not evidence-based. All included centres perform medical aftercare following suture removal. It is assumed that different treatment strategies show different cost-benefit ratios. In the face of the diversity, a systematic analysis is required to develop an optimised regimen for all patients.

Indications for intraoperative anterior segment optical coherence tomography in corneal surgery.

PURPOSE: Recently, intraoperative optical coherence tomography (iOCT) has evolved in the field of ophthalmic surgery. So far, the use of iOCT was mainly focused to lamellar keratoplasty, especially deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK). The aim of this study was to report our experiences with iOCT to introduce new possibilities of this application. METHODS: We used iOCT in 18 patients who underwent the following surgeries: DALK, DMEK, penetrating keratoplasty, autologous limbal transplantation, transscleral suture fixation of a posterior chamber lens, pannus removal on corneal surface and newborn investigation in Peters' anomaly. We obtained qualitative video data for all procedures. RESULTS: With the iOCT, the cannula placement during DALK preparation of the recipient cornea and bubble formation could be visualized to improve the success rate of the big bubble injection. In DMEK, the iOCT enables the visualization of Descemet's membrane removal in the recipient and graft orientation as well as better control of graft attachment. The iOCT enables intraoperative visualization of the graft-host interface during penetrating keratoplasty. During autologous limbal transplantation, transscleral suture fixation of a posterior chamber lens and removal of corneal surface pannus the iOCT is capable of showing the thickness of lamellar preparations to avoid penetrations and to save healthy recipient's tissue. CONCLUSION: The iOCT is a helpful device for intraoperative anterior segment imaging not only for DALK and DMEK. It is also beneficial in penetrating keratoplasty and every other form of lamellar preparation during corneoscleral surgery.

[Automated Cell Counting Using "Deep Learning" in Donor Corneas from Organ Culture Achieves High Precision and Accuracy]. / Automatisierte Zellzählung in Spenderhornhäuten aus Organkultur mittels "Deep Learning" erreicht hohe Präzision und Genauigkeit.

BACKGROUND: Human corneal grafts from organ culture need to have more than 2000 endothelial cells/mm2 to be suitable for transplantation. Measurement of the endothelial cell density is complicated by invisible cell borders in phase contrast microscopy, as well as by limited areas for counting due to folds in the Descemet membrane of the swollen corneal grafts. To date, no automated counting method for measuring the endothelial cell density exists. The neuronal network U-Net has already proven itself in automated segmentation of specular microscopy images of human corneal endothelium. The aim of this study was the application of the U-Net in the quality control of human corneal grafts. MATERIAL AND METHODS: Training of the U-Net was performed using 100 manually tagged endothelial cell images of corneal grafts from the Lions eye bank in Baden-Württemberg. Another 100 images were obtained for testing the precision of measurements of the U-Net. These were adjudged manually by a) an experienced investigator and b) a less experienced ophthalmologist. The endothelial cells in identical images were then counted automatically by the trained U-Net. Comparison with the manually counted results was drawn by Pearson correlation. RESULTS: The correlation coefficient between the U-Net and the experienced investigator as gold standard was 0.9. The correlation coefficient between the less experienced ophthalmologist and the gold standard was only 0.81. Both correlations were statistically highly significant (p < 0.0001). DISCUSSION: The strong correlation between the U-Net and the gold standard points out that, given medical approval, effective assistance for eye banks is possible in quality control by automated counting. This could improve objectivity and efficiency of work flow.

Graft dislocation and graft failure following Descemet membrane endothelial keratoplasty (DMEK) using precut tissue: a retrospective cohort study.

PURPOSE: Although the functional results following DMEK are better than after DSAEK, DSAEK still seems to be the standard procedure, as surgeons fear losing grafts during DMEK graft preparation. Therefore, eye banks offer precut DMEK grafts for direct use by the surgeon. Here, we analysed the functional results and complication rates for a precut technique compared to fresh preparations. METHODS: We retrospectively compared 453 standard to 11 precut (1-2 days before surgery) DMEK cases. Precut preparations did not differ from the standard preparation, except that the preparation was stopped after trephination with the graft still attached in a small central area. The preparation had to be completed before surgery by peeling off the centrally attached part of the graft. This technique was first tested in an experimental series of 14 grafts, which were unsuitable for transplantation. All surgeries were performed in the same standardized way. RESULTS: There was no significant endothelial cell loss during the storage period following precut preparation. We found a statistically significantly higher endothelial cell loss and graft failure rate for the precut grafts. CONCLUSION: Because of the statistically significant higher graft failure rate in the precut group, we stopped using this technique, so the numbers in this retrospective case series are small. The higher graft failure rate may be explained by (ultra)structural changes in the DMEK graft (e.g. accumulation of dextran) during the second storage period. Therefore, careful evaluation is recommended before using precut DMEK grafts stored in dextran containing media in order to avoid early primary graft failures.

Descemet membrane endothelial keratoplasty for graft failure following penetrating keratoplasty.

PURPOSE: Descemet membrane endothelial keratoplasty (DMEK) is superior to penetrating keratoplasty (PK) in terms of visual rehabilitation, intraoperative safety and risk of rejection. Therefore, it seems reasonable to perform DMEK in eyes with endothelial failure following PK. We herein report our first clinical results. METHODS: Nineteen eyes with endothelial graft failure following PK were treated with DMEK. The majority of these eyes (12) had limited visual potential. The major indication for DMEK was pain relief in patients with bullous keratopathy. Visual acuity (VA), central corneal thickness (CCT), rate of graft dislocations, graft survival, graft rejections and other complications were extracted from the medical records. RESULTS: Although comorbidities limiting VA were present in 12 of the 19 eyes, VA increased from 0.05 to 0.1 (median) in 16 eyes. CCT decreased substantially (range 63-363 µm). Rebubbling was necessary in five eyes with incomplete graft adherence. There were two immunologic graft reactions and three graft failures. No major complications like endophthalmitis or expulsive bleeding occurred. CONCLUSIONS: DMEK is feasible to treat endothelial graft failure following PK. This is even true for eyes with limited visual potential.

Extracellular localization of catalase is associated with the transformed state of malignant cells.

Oncogenic transformation is dependent on activated membrane-associated NADPH oxidase (NOX). However, the resultant extracellular superoxide anions are also driving the NO/peroxynitrite and the HOCl pathway, which eliminates NOX-expressing transformed cells through selective apoptosis induction. Tumor progression is dependent on dominant interference with intercellular apoptosis-inducing ROS signaling through membrane-associated catalase, which decomposes H2O2 and peroxynitrite and oxidizes NO. Particularly, the decomposition of extracellular peroxynitrite strictly requires membrane-associated catalase. We utilized small interfering RNA (siRNA)-mediated knockdown of catalase and neutralizing antibodies directed against the enzyme in combination with challenging H2O2 or peroxynitrite to determine activity and localization of catalase in cells from three distinct steps of multistage oncogenesis. Nontransformed cells did not generate extracellular superoxide anions and only showed intracellular catalase activity. Transformed cells showed superoxide anion-dependent intercellular apoptosis-inducing ROS signaling in the presence of suboptimal catalase activity in their membrane. Tumor cells exhibited tight control of intercellular apoptosis-inducing ROS signaling through a high local concentration of membrane-associated catalase. These data demonstrate that translocation of catalase to the outside of the cell membrane is already associated with the transformation step. A strong local increase in the concentration of membrane-associated catalase is achieved during tumor progression and is controlled by tumor cell-derived H2O2 and by transglutaminase.

Trabeculectomy ab interno with the Trabectome® as a therapeutic option for uveitic secondary glaucoma.

PURPOSE: Treatment of secondary glaucoma in uveitis patients is challenging. Owing to the young age of these patients, sufficient lowering of the intraocular pressure (IOP) is essential to prevent progression of visual field loss. However, because of the chronic inflammatory stimulus, filtration surgery has an increased risk of failure, especially in patients who have previously undergone surgery. Therefore, minimally invasive glaucoma surgery is a valuable alternative. METHODS: The clinical records of 24 consecutive patients with uveitic secondary glaucoma who underwent trabeculectomy ab interno with the Trabectome® at the Eye Center of the Albert-Ludwigs University of Freiburg between June 2009 and June 2014 (registered in the Freiburg trabectome database) were retrospectively analyzed. The general baseline information for each patient included age, gender, glaucoma type, ocular medication and current IOP. The postoperative IOP and number of antiglaucomatous medications were recorded at each visit. Statistical analyses were performed using the Kaplan-Meier estimator and Dunnett's t-test. RESULTS: The mean IOP before surgery was 31 ± 6.7 mmHg (median 32 mmHg). Both the IOP and the number of medications significantly decreased over the various follow-up intervals after trabeculectomy ab interno with the Trabectome®. Patients with follow-ups continuing past one year showed an IOP-reduction of approximately 40 % and a medication number reduction from 2 to 0.67. The failure rate (necessitating further glaucoma surgery) was N = 3 (12.5 %) patients. CONCLUSIONS: Trabeculectomy ab interno with the Trabectome® is a minimally invasive and effective method for controlling IOP in uveitic secondary glaucoma.

Giant cell arteritis: diagnostic accuracy of MR imaging of superficial cranial arteries in initial diagnosis-results from a multicenter trial.

PURPOSE: To assess the diagnostic accuracy of contrast material-enhanced magnetic resonance (MR) imaging of superficial cranial arteries in the initial diagnosis of giant cell arteritis ( GCA giant cell arteritis ). MATERIALS AND METHODS: Following institutional review board approval and informed consent, 185 patients suspected of having GCA giant cell arteritis were included in a prospective three-university medical center trial. GCA giant cell arteritis was diagnosed or excluded clinically in all patients (reference standard [final clinical diagnosis]). In 53.0% of patients (98 of 185), temporal artery biopsy ( TAB temporal artery biopsy ) was performed (diagnostic standard [ TAB temporal artery biopsy ]). Two observers independently evaluated contrast-enhanced T1-weighted MR images of superficial cranial arteries by using a four-point scale. Diagnostic accuracy, involvement pattern, and systemic corticosteroid ( sCS systemic corticosteroid ) therapy effects were assessed in comparison with the reference standard (total study cohort) and separately in comparison with the diagnostic standard TAB temporal artery biopsy ( TAB temporal artery biopsy subcohort). Statistical analysis included diagnostic accuracy parameters, interobserver agreement, and receiver operating characteristic analysis. RESULTS: Sensitivity of MR imaging was 78.4% and specificity was 90.4% for the total study cohort, and sensitivity was 88.7% and specificity was 75.0% for the TAB temporal artery biopsy subcohort (first observer). Diagnostic accuracy was comparable for both observers, with good interobserver agreement ( TAB temporal artery biopsy subcohort, κ = 0.718; total study cohort, κ = 0.676). MR imaging scores were significantly higher in patients with GCA giant cell arteritis -positive results than in patients with GCA giant cell arteritis -negative results ( TAB temporal artery biopsy subcohort and total study cohort, P < .001). Diagnostic accuracy of MR imaging was high in patients without and with sCS systemic corticosteroid therapy for 5 days or fewer (area under the curve, ≥0.9) and was decreased in patients receiving sCS systemic corticosteroid therapy for 6-14 days. In 56.5% of patients with TAB temporal artery biopsy -positive results (35 of 62), MR imaging displayed symmetrical and simultaneous inflammation of arterial segments. CONCLUSION: MR imaging of superficial cranial arteries is accurate in the initial diagnosis of GCA giant cell arteritis . Sensitivity probably decreases after more than 5 days of sCS systemic corticosteroid therapy; thus, imaging should not be delayed. Clinical trial registration no. DRKS00000594 .

Indications, techniques, and graft survival of mini and corneo-scleral tectonic keratoplasties: A retrospective single-center case series.

PURPOSE: Tectonic keratoplasties (TK) are used to treat corneal and scleral perforations and to prevent the loss of the eye. In this study, we retrospectively analyzed indications, surgical procedures, and outcomes of eccentric mini and corneo-scleral tectonic keratoplasties with respect to anatomical survival and clear graft survival rates to identify risk factors for graft failure. METHODS: This retrospective study includes 33 eccentric mini (graft diameter <6 mm) and/or corneo-scleral TK of 32 consecutive patients of a total of 41 TK carried out between 2005 and 2020 in the Eye Center, University of Freiburg, Germany, making up 0.7% of all keratoplasties performed during this period (n = 5557). Patient and graft specific data were extracted from medical files. Anatomical survival-defined as achieving integrity of the globe without further surgical interventions-and clear graft survival-defined as persisting graft clarity-were estimated using the Kaplan-Meier method. We also fitted Cox proportional hazard models to account for factors influencing anatomical and clear graft survival. RESULTS: Median duration of anatomical success was 72.5 months (95% confidence interval (CI) 18.1-infinite (inf.)) and median duration of clear graft survival was 29.6 months (95% CI 12.5-Inf.). The 1-year survival rate for anatomical survival was 67.6% (95% CI 52.2% - 87.6%) and for clear graft survival 66.4% (95% CI 50.5%- 87.1%). No enucleation was necessary during this time-period. Non-inflammatory primary causes (n = 14) presented a trend towards better anatomical survival rates (median remained above 0.75 during follow-up) compared to inflammatory primary causes (n = 19, median 18.1 months (95% CI 2.8 - inf.)) and longer clear graft survival (median 29.6 months (95% CI 12.5 - inf.) versus 13.1 months (95% CI 3.2 - inf.)). Corneo-scleral grafts (n = 18) compared to corneal grafts (n = 15) showed a trend towards better anatomical survival (more than 50% of eyes did not fail during follow-up period (95% CI 21.9-Inf. months) versus 18.1 months (95% CI 2.4-Inf.)) and clear graft survival (median 29.6 months (95% CI 12.6-Inf.) versus 6.2 months (95% CI 2.8-Inf.)). Old age (n = 11, 75.2 - 90.1 years) compared to young age (n = 11, 6.2 - 60.2 years) was the only hazard ratio (hazard ratio 0.04 (95% CI 0.002-0.8)) that reached the level of significance (p = 0.03). CONCLUSION: Eccentric TK is helpful in the successful treatment of a variety of severe eye diseases. Patients at young age, with pre-existing inflammatory conditions or corneal TK are at higher risk for anatomical failure as well as clear graft failure and therefore need to be monitored closely.

Multiple protective functions of catalase against intercellular apoptosis-inducing ROS signaling of human tumor cells.

Tumor cells are protected against intercellular reactive oxygen species (ROS)-mediated apoptosis signaling mediated by the HOCl and/or the nitric oxide (NO)/peroxynitrite signaling pathway. We have recently shown that tumor cell resistance against HOCl signaling can be abrogated through inhibition of catalase. The protection of tumor cells against the NO/peroxynitrite signaling pathway has remained enigmatic so far. Here, we show that suboptimal inhibition of catalase by 3-aminotriazole or a monoclonal antibody against catalase, as well as partial knockdown of catalase by specific siRNA allows selective reactivation of the NO/peroxynitrite pathway in MKN 45 gastric carcinoma cells, followed by the HOCl pathway at higher inhibitor or siRNA concentrations. In SKN-MC Ewing sarcoma cells, catalase inhibition causes apoptosis induction solely based on the NO/peroxynitrite pathway. Protection against NO/peroxynitrite signaling is shown to be due to the potential of catalase to decompose peroxynitrite. The direct interaction of catalase with peroxynitrite is verified through the detection of compound I (CAT Fe(IV)=O(+)*) after the interaction of peroxynitrite with catalase. In a complementary experiment, addition of catalase protects sensitive transformed cells against ROS-mediated apoptosis induction. Thus, the expression of membrane-associated catalase is sufficient to protect tumor cells against multiple intercellular ROS-mediated signaling pathways.

[Progressive loss of vision in cone dystrophy. Search for evidence with macular OCT and multifocal ERG]. / Progressive Visusminderung bei Zapfendystrophie. Spurensuche im Makula-OCT und Multifokal-ERG.

A 53-year-old patient consulted our practice clinic complaining of progressive visual loss, increased glare sensitivity and color sense disorder. Extensive diagnostic investigation, including multifocal ERG (mfERG) and macular thickness map with the help of optical coherence tomography (OCT), supported the suspected diagnosis of a cone dystrophy. There are, however, no established therapeutic options. A diagnostic confirmation by means of molecular genetics was not successful.

Use of Donor Corneas From Pseudophakic Eyes for Descemet Membrane Endothelial Keratoplasty.

PURPOSE: The prevalence of pseudophakia increases with age and affects more than 30% of people older than 80 years. Because grafts from older donors seem to be more suitable for Descemet membrane endothelial keratoplasty (DMEK) surgery rather than grafts from younger donors, eye bank technicians and corneal surgeons have to deal with corneas from pseudophakic donors for DMEK graft preparation. However, graft preparation from corneas of pseudophakic donors can be more complicated. METHODS: We retrospectively analyzed our donor registry for the prevalence of pseudophakia. We compared grafts from phakic and pseudophakic donors concerning graft survival, rebubbling rates, and endothelial cell loss after DMEK surgery. RESULTS: More than 20% of our donors were pseudophakic, of which 35% were primarily suitable for transplantation. Regarding the comparison of grafts from phakic and pseudophakic donors used for DMEK, we observed comparable survival rates (90% after 3 years) and similar endothelial cell loss (30% with an endothelial cell density above 1000 cell/mm after 3 years) but significantly lower rebubbling rates for grafts from pseudophakic donors (18% vs. 28%). CONCLUSIONS: Our data strongly suggest that pseudophakic persons should not be excluded from corneal donation because success rates after DMEK with grafts from pseudophakic eyes are comparable to those with grafts from phakic eyes. However, in the eye bank, grafts from pseudophakic donors have a higher primary discard rate because of low endothelial cell counts.

Influence of Postoperative Intraocular Pressure on Graft Detachment After Descemet Membrane Endothelial Keratoplasty.

PURPOSE: Descemet membrane endothelial keratoplasty (DMEK) seems to be the most promising technique for treating endothelium-related disorders of the cornea. However, graft detachment is a frequent complication. It often can be treated by rebubbling procedures. Unfortunately, this increases the risk of subsequent graft failure. It is therefore essential to define risk factors for graft detachment in DMEK. In this study, postoperative intraocular pressure (IOP) is investigated in this regard. METHODS: In total, 1047 DMEK procedures in patients with Fuchs endothelial dystrophy or bullous keratopathy were reviewed. All rebubbling procedures were recorded as well as postoperative IOP values (first measure 2 hours postoperatively and highest and lowest value within 3 days after surgery), donor factors (donor age, organ culture time, and endothelial cell count), and whether DMEK surgery had been combined with cataract surgery (triple-DMEK). Incidence rates were estimated with the Kaplan-Meier method. Cox regression was used to assess statistical significance. RESULTS: The overall rebubbling rate was 24% after 8 weeks. Relative dips in IOP may be associated with a higher risk for graft detachment (hazards ratio = 0.41; P < 0.001). Graft detachment was neither significantly influenced by donor factors, first or maximum IOP, nor by simultaneous cataract surgery (triple-DMEK). CONCLUSIONS: Avoiding dips in IOP may reduce the risk for graft detachment after DMEK. To prevent lowering of IOP values in the early postsurgical period, it may be advisable to achieve tight surgical wounds at the end of DMEK surgery and optimal filling of the anterior chamber with air and optionally with gas.

Instrumented indentation for determination of mechanical properties of human cornea after ultraviolet-A crosslinking.

UVA crosslinking is used for treatment of corneal diseases such as keratoconus in order to stabilize the corneal tissue by crosslinking of the collagen fibers. It has been shown that the crosslinking treatment leads to a stiffening of the central corneal tissue. However, knowledge of lateral extent of the corneal stiffening as well as a systematic study of the mechanical response of human cornea is still missing. In our study we measured the stiffness (elastic modulus) of the anterior surface of healthy and crosslinked human corneas by instrumented indentation using a spherical indenter. The results show that the stiffness of the central and paracentral cornea increased almost two times after the crosslinking but the stiffening effect rapidly decreased towards the periphery of the radiation field. These new insights into the understanding of the biomechanical response of corneal crosslinking shall contribute to a better understanding and an optimization of this perspective medical treatment. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1413-1420, 2018.

Intermediate uveitis: pattern of etiology, complications, treatment and outcome in a tertiary academic center.

BACKGROUND: Patients with intermediate uveitis (IU) represent a heterogenous group characterized by a wide spectrum of etiologies and regional differences. Aim of the study was to analyze the characteristics of patients with IU examined in an academic center in Germany. METHODS: We conducted a retrospective analysis of the clinical records of all patients with intermediate uveitis referred to the Eye Center, University of Freiburg from 2007 to 2014. Diagnosis followed the Standardization in Uveitis Nomenclature (SUN) criteria. Data analysis included: etiology of IU, demographics, complications, treatment and visual acuity. RESULTS: We identified 159 patients with intermediate uveitis during that period. Mean age at diagnosis was 35 years. Most are female (64%), and the mean duration of IU was 6.1 years (range 1 month - 35 years). Etiology of IU was idiopathic in 59%. Multiple sclerosis (MS) (20%) and sarcoidosis (10%) were frequent systemic causes of IU. Other etiologies including infectious diseases (tuberculosis, borreliosis) or immune-mediated conditions (eg, after vaccination) were present in 11%. The pattern of complications included macular edema (CME) (36%), cataract (24%), secondary glaucoma (7%), and epiretinal membrane formation (19%). Periphlebitis and optic neuritis were more frequent in conjunction with MS. Treatment comprised local and systemic steroids, immunosuppressive agents, biologics, and surgery. Best corrected visual acuity was better than 20/25 in 60% of the eyes after more than 10 years of follow-up. CONCLUSIONS: In our German academic center, most IU cases were idiopathic or associated with MS or sarcoidosis. In contrast to other countries, infectious cases were rare. Patients' overall visual prognosis is favorable even when the duration of IU has been long and and despite numerous complications.

Switch of Intravitreal Therapy for Macular Edema Secondary to Retinal Vein Occlusion from Anti-VEGF to Dexamethasone Implant and Vice Versa.

PURPOSE: To evaluate the anatomical and functional outcome of intravitreal dexamethasone implant for macular edema secondary to central (C) or branch (B) retinal vein occlusion (RVO) in patients with persistent macular edema (ME) refractory to intravitreal antivascular endothelial growth factor (VEGF) treatment compared to treatment naïve patients and to dexamethasone-refractory eyes switched to anti-VEGF. METHODS: Retrospective, observational study including 30 eyes previously treated with anti-VEGF (8 CRVO, 22 BRVO, mean age 69 ± 10 yrs), compared to 11 treatment naïve eyes (6 CRVO, 5 BRVO, 73 ± 11 yrs) and compared to dexamethasone nonresponders (2 CRVO, 4 BRVO, 69 ± 12). Outcome parameters were change in best-corrected visual acuity (BCVA) and central foveal thickness (CFT) measured by spectral-domain optical coherence tomography. RESULTS: Mean BCVA improvement after switch to dexamethasone implant was 4 letters (p = 0.08), and treatment naïve eyes gained 10 letters (p = 0.66), while we noted no change in eyes after switch to anti-VEGF (p = 0.74). Median CFT decrease was most pronounced in treatment naïve patients (-437 µm, p = 0.002) compared to anti-VEGF refractory eyes (-170 µm, p = 0.003) and dexamethasone-refractory eyes (-157, p = 0.31). CONCLUSIONS: Dexamethasone significantly reduced ME secondary to RVO refractory to anti-VEGF. Functional gain was limited compared to treatment naïve eyes, probably due to worse BCVA and CFT at baseline in treatment naïve eyes.