Daniel Böhringer

Influencing factors on chronic endothelial cell loss characterised in a homogeneous group of patients.

Background/aim: Advanced donor age, long death to excision time interval, and factors related to organ culture can trigger unfavourable intracellular processes in the graft endothelium and contribute to chronic endothelial cell loss after penetrating keratoplasty. The aim of this study was to investigate factors influencing chronic endothelial cell loss in a homogeneous group of patients. Methods: 177 patients after first normal risk keratoplasties for keratoconus were retrospectively selected from the quality control database of our clinic. For 71 of them at least four central endothelial cell density values were documented in follow up. From these patients, only those 53 without any further intraocular procedures, without glaucoma, and without graft rejection were considered. A scatter plot of logarithmised endothelial cell density values against postoperative time was drawn for each patient. The slope of the regression line then equals the constant of decay in central endothelial cell density. The influence of donor age and storage time in organ culture on this index value of cell loss was investigated by means of linear regression analysis. Results: Mean loss of central endothelial cell density was 16.7% per year. Regression analysis revealed a statistically significant negative linear effect of both postmortem time (β = –0.324; p = 0.014) and donor age (β = –0.282; p = 0.036) and a trend for storage time in organ culture (β = –0.195; p = 0.142) in a combined linear regression model. Conclusion: Increased postmortem time and advanced donor age exert a significant negative effect on chronic endothelial cell loss. Storage time in organ culture seems to be third influencing factor. These negative influences may be reduced by compensating advanced donor age with minimised postmortem and storage time.

Influence of donor characteristics on descemet membrane endothelial keratoplasty.

Purpose: Penetrating keratoplasty is being replaced by posterior lamellar techniques like Descemet stripping automated endothelial keratoplasty or Descemet membrane endothelial keratoplasty (DMEK) for the surgical treatment of patients with endothelial insufficiency. Although DMEK leads to the best visual results, Descemet stripping automated endothelial keratoplasty is still the standard procedure for many surgeons because it is technically more standardized. Here, we investigated how donor characteristics may influence DMEK surgery. Methods: After in vitro preparation of DMEK grafts (n = 28), we measured the width of the graft roll, which we correlated to various donor characteristics. In 31 DMEK cases, we measured the intraoperative time from implantation to attachment of the graft, which we correlated to the respective donor characteristics and endothelial cell loss. We used Pearsons method and a multifactorial linear model for the statistical assessments. Results: We found a statistically significant correlation between donor age (P < 0.001) and endothelial cell density (P < 0.05), and the width of the DMEK rolls. That is, older donors and grafts with higher endothelial cell densities formed broader graft rolls. Donor age also showed a trend to directly influence the unfolding time that took longer using younger grafts. Furthermore, the relative endothelial cell loss increased with longer unfolding times. Conclusions: We found that donor age and endothelial cell density influence the properties of DMEK grafts, and thereby the duration of the surgical procedure. Increased unfolding times result in higher endothelial cell loss. Therefore, it seems reasonable to accept preferably older donors with high endothelial cell densities for DMEK, which may be particularly true for inexperienced surgeons or complex clinical situations.

Improvement of graft prognosis in penetrating normal-risk keratoplasty by HLA class I and II matching

AbstractBackground Owing to contradictory results, HLA matching in penetrating keratoplasty still is equivocal. Different surgical techniques in multicentre studies, missing risk differentiation in high-risk situations, and faulty HLA typing can be identified as main reasons for these contradictory results. In this monocentre study, the value of HLA class I and II matching (A, B, DR loci) was examined in a homogeneous group of 418 normal-risk keratoplasty patients using serological typing techniques for HLA class I and immuno-genetic typing techniques for class II.Methods Penetrating normal-risk keratoplasty was performed in two groups of patients (group I with 0–2, group II with 3–6 mismatches in the A/B/DR loci). All surgery was carried out by three experienced surgeons according to a standardized scheme. Furthermore, postoperative therapy and controls were standardized. There were no statistically significant differences between the two study groups with regard to the number of ABO or H-Y compatibilities, patient age, patient gender, ratio of previous intraocular surgery, ratio of triple procedures, indication for surgery, follow-up period, donor age, donor gender, post-mortem time of the graft, and endothelial cell density of the graft at the end of organ culture. All HLA typing was performed in a quality-controlled laboratory, serologically for HLA class I (A and B loci) and immunogenetically for HLA class II (DR locus).Results At 4 years postoperatively, the ratio of clear and rejection-free graft survival was 92% in group I and 66% in group II (Kaplan–Meier estimation, log rank test, P=0.03). Monovariate analysis in the Cox model gave no influence of solitary HLA class I or II matching, but only an influence of combined HLA class I and II matching (P=0.03).Conclusions In this monocentre study with proper typing techniques, the beneficial effect of HLA class I plus II matching on clear and rejection-free graft survival could be demonstrated in a homogeneous group of normal-risk keratoplasty patients.

Long-term graft survival in penetrating keratoplasty: the biexponential model of chronic endothelial cell loss revisited.

Aim: To present a novel interpretation of the biexponential nature of chronic endothelial cell loss after penetrating keratoplasty (PK). We hypothesize that the fast component of endothelial cell loss reflects the endothelial cells of graft origin. The slow component might just reflect cell loss of the recipient endothelium. We investigate herein whether this hypothesis is in line with long-term survival in bullous keratopathy (BK: almost no endothelium in the recipient bed) and keratoconus (KK: recipient bed with plenty of endothelium). Methods: We reviewed endothelial graft failures in PK for BK (n = 88) and KK (n = 87). Patients with immune reactions or a history of glaucoma were excluded. We built a statistical model to predict graft failures from biexponential endothelial cell loss and compared this data to the actual outcomes. Results: After 15 years, the incidence of late endothelial failures was 8% in KK and 33% in BK. The 95% confidence intervals of the simulated outcomes corresponded completely to the actual outcomes during follow-up. Conclusions: Our novel interpretation of the biexponential model is in line with long-term data of PK for BK and KK. Our findings highlight the importance of the recipient bed endothelial reservoir on the long-term prognosis in PK.

Matching of the minor histocompatibility antigen HLA-A1/H-Y may improve prognosis in corneal transplantation.

Background. Minor histocompatibility (H) antigens are peptides of allelic intracellular proteins that play an important role in human leukocyte antigen (HLA) matched transplantations. In an animal model of keratoplasty, minor H antigens have even been reported to exceed the immunogenicity of major H antigens (MHC). This investigation is to assess any benefit of matching the broadly expressed gender (H-Y) and HA-3 antigens in HLA-A1 donor positive human keratoplasty. Methods. A total of 229 HLA-A1 donor positive keratoplasties were analyzed. A Cox proportional hazards model and Kaplan-Meier analysis were applied to estimate the effect of H-Y or HA-3 mismatches on rejection-free graft survival. Results. Eighty-one cases were mismatched for H-Y (male donor to female recipient). A mean follow up of two years showed graft survival as high as 88% in the H-Y compatible group compared to only 77% in the H-Y mismatched group (P=0.02). Eight out of 62 cases were mismatched for HA-3. No statistically significant influence of HA-3 matching on rejection-free graft survival was observed (85% vs. 73%, P=0.52). Conclusion. HLA-A1/H-Y matching and matching for other broadly expressed minor H antigens may further improve prognosis in keratoplasty.

Beneficial effect of matching at the HLA-A and -B amino-acid triplet level on rejection-free clear graft survival in penetrating keratoplasty.

Objective. The beneficial effect of human leukocyte antigen (HLA) matching on long-term prognosis in penetrating keratoplasty is now unequivocal but has to be weighed against the additional waiting period on an individual basis. HLAMatchmaker is a molecularly based algorithm for histocompatibility determination that can identify immunologically acceptable mismatches and thus potentially reduce time on the waiting list dramatically without negatively affecting prognosis. Methods. The HLAMatchmaker algorithm (triplet-string matching) was applied on each of 545 normal-risk keratoplasties for which complete HLA type was known at split-level resolution. Two homogenous groups were defined. Group I consisted of the 147 penetrating keratoplasties with up to 13 triplet-string mismatches (the typical upper limit of foreign in case of a single HLA-A or HLA-B allele mismatch) and was compared to the remaining 398 patients with more triplet mismatches (group II) using the Kaplan-Meier method and log-rank statistics. Analysis of clear graft survival on the basis of conventional HLA-A and HLA-B matching was performed as well. Reduction of time on the waiting list as compared to conventional HLA-A and HLA-B matching was predicted individually. Results. Triplet-string matching yielded 85% rejection-free clear graft survival 3 years after penetrating keratoplasty in group I but only 76% in group II (P <0.05), whereas conventional HLA-A and HLA-B matching did not result in any statistically significant reduction of immune reactions because of lack of statistical power (P =0.08). Triplet-string matching (13 mismatches accepted) reduces median time on the waiting list by 80%. Conclusions. Triplet-string matching seems to improve mid- to long-term prognosis in penetrating keratoplasties while simultaneously reducing time on the waiting list in most cases. It should thus be considered for histocompatibility determination in penetrating keratoplasty.

Aganirsen Antisense Oligonucleotide Eye Drops Inhibit Keratitis-Induced Corneal Neovascularization and Reduce Need for Transplantation: The I-CAN Study

OBJECTIVE Eye drops of aganirsen, an antisense oligonucleotide preventing insulin receptor substrate-1 expression, inhibited corneal neovascularization in a previous dose-finding phase II study. We aimed to confirm these results in a phase III study and investigated a potential clinical benefit on visual acuity (VA), quality of life (QoL), and need for transplantation. DESIGN Multicenter, double-masked, randomized, placebo-controlled phase III study. PARTICIPANTS Analysis of 69 patients with keratitis-related progressive corneal neovascularization randomized to aganirsen (34 patients) or placebo (35 patients). Patients applied aganirsen eye drops (86 μg/day/eye) or placebo twice daily for 90 days and were followed up to day 180. MAIN OUTCOME MEASURES The primary end point was VA. Secondary end points included area of pathologic corneal neovascularization, need for transplantation, risk of graft rejection, and QoL. RESULTS Although no significant differences in VA scores between groups were observed, aganirsen significantly reduced the relative corneal neovascularization area after 90 days by 26.20% (P = 0.014). This improvement persisted after 180 days (26.67%, P = 0.012). Aganirsen tended to lower the transplantation need in the intent-to-treat (ITT) population at day 180 (P = 0.087). In patients with viral keratitis and central neovascularization, a significant reduction in transplantation need was achieved (P = 0.048). No significant differences between groups were observed in the risk of graft rejection. However, aganirsen tended to decrease this risk in patients with traumatic/viral keratitis (P = 0.162) at day 90. The QoL analyses revealed a significant improvement with aganirsen in composite and near activity subscores (P = 0.039 and 0.026, respectively) at day 90 in the per protocol population. Ocular and treatment-related treatment-emergent adverse events (TEAEs) were reported in a lower percentage with aganirsen compared with placebo. Only 3 serious TEAEs (2 with aganirsen and 1 with placebo) were considered treatment-related. CONCLUSIONS This first phase III study on a topical inhibitor of corneal angiogenesis showed that aganirsen eye drops significantly inhibited corneal neovascularization in patients with keratitis. The need for transplantation was significantly reduced in patients with viral keratitis and central neovascularization. Topical application of aganirsen was safe and well tolerated.

Cystoid macular oedema following Descemet membrane endothelial keratoplasty

Background To determine the incidence and potential risk factors of cystoid macular oedema (CMO) following Descemet membrane endothelial keratoplasty (DMEK) with or without simultaneous cataract surgery. Methods In this study, 155 eyes of 88 patients suffering from Fuchs endothelial dystrophy (81%), bullous keratopathy (17.6%) or other corneal diseases (1.4%) underwent DMEK. 52% were pseudophacic (DMEK) and 48% received simultaneous cataract surgery (DMEK combined with cataract surgery (Triple-DMEK)) at the Eye Center at Albert Ludwigs University of Freiburg between May 2011 and June 2013. Spectral-domain optical coherence tomography (SD-OCT) was performed 6 weeks, 3 months and 6 months following (Triple-)DMEK and in unscheduled visits due to limited or decreased visual acuity. The medical records were reviewed for pre-existing comorbidities limiting visual acuity. Patients with a history of macular oedema were excluded. We estimated the incidence of CMO using the Kaplan–Meier method. Potential risk factors for CMO were analysed with a Cox regression analysis and Pearsons correlation. The Cox model included the following variables: patient age and axial length, simultaneous cataract surgery, rate of rebubbling, donor age and donor endothelial cell density. Results 13% of all eyes developed a single episode of CMO at the end of the follow-up. After 6 months, 13.3% of eyes following Triple-DMEK and 12.5% of eyes following DMEK showed CMO. There was a statistically significant correlation between CMO development and best spectacle corrected visual acuity. Long axial length had a protective effect on CMO development (HR=0.3; p=0.03). Under medical therapy, central foveal thickness decreased in all patients. CMO did not have a relevant effect on long-term visual acuity. Conclusions CMO is a frequent complication following DMEK in phacic and pseudophacic eyes. The prognosis is excellent given medical treatment. We recommend regular SD-OCT monitoring during the first 6 months following DMEK.

Clear graft survival and immune reactions following emergency keratoplasty

BackgroundEmergency penetrating keratoplasty is said to have a poorer outcome than conventional keratoplasty. We performed a retrospective analysis of 272 cases of emergency keratoplasty to evaluate this hypothesis.MethodsWe analysed 272 cases of emergency keratoplasty and compared the results with a control group of 1,257 scheduled normal-risk keratoplasties and 407 scheduled high-risk keratoplasties. Kaplan-Meier estimations were performed to estimate the percentage of clear graft survival and development of immune reactions. Indications for emergency keratoplasty were microbial diseases (n=109, acanthamoeba, bacteria, fungi), herpes simplex virus infections (n=83), ulcers due to immunological diseases (n=63), and 17 cases of ulcers of unknown origin.ResultsWithin 1,500 postoperative days, grafts following emergency keratoplasty suffered statistically significantly more graft failures (clear graft survival, 67.9 vs. 86.9%, P<0.01) and immune reactions (grafts free from immune reactions, 62.8 vs. 78.6%, P<0.01) than grafts following scheduled, normal-risk keratoplasty. There was no statistically significant difference between emergency and scheduled high-risk keratoplasties (clear graft survival, 67.9 vs. 70.2%, and grafts free from immune reactions, 62.8 vs. 66.8%). For emergency keratoplasties, systemic immunosuppression (with cyclosporin A and/or mycophenolatmophetil) had a statistically significant positive effect on clear graft survival (77.4 vs. 63.5%, P=0.01), but not on the development of immune reactions (62.8 vs. 62.3%). A sub-group analysis showed that the effect on clear graft survival was mainly an effect on the underlying systemic immunological disease that had lead to emergency keratoplasty.ConclusionThis retrospective analysis revealed that clear graft survival is limited following emergency keratoplasty. As in high-risk situations, systemic immunosuppression may be the key to improving prognosis following emergency keratoplasty in the long run.

Switch of anti-VEGF agents is an option for nonresponders in the treatment of AMD

BackgroundAlthough anti-VEGF therapy of exudative AMD with bevacizumab and ranibizumab proved efficacious in the majority of patients, CNV activity does not respond to continued treatment after repeated injections in a considerable amount of patients. These are referred to as nonresponders. A change of the drug to bevacizumab or ranibizumab could possibly offer an alternative option for the treatment of nonresponding exudative AMD.Methods and materialsA total of 138 nonresponders who switched therapy from bevacizumab to ranibizumab (n=114) or vice versa (n=24) were included in a retrospective study. Visual acuity (VA) and foveal thickness before and after the switch of therapy were compared. By means of linear regression analysis, we analyzed possible prognostic factors associated with a favorable outcome for visual acuity.ResultsLinear regression analysis revealed a statistically significant benefit for nonresponders when treatment was changed to a different anti-VEGF drug (bevacizumab or ranibizumab). VA at the time of the switch was positively correlated with a beneficial development of VA after changing the drug. There was no significant correlation with age, macular thickness, number of injections before the switch, or the development of VA under treatment before the switch. Both patients switching to Avastin and Lucentis benefitted without statistically significant differences.ConclusionsAn exchange of bevacizumab with ranibizumab or vice versa should be considered in nonresponders in the treatment of exudative AMD. Further prognostic factors may help to identify patients who might benefit from a switch. These factors should be investigated in further studies.