Contrast sensitivity with bifocal intraocular lenses is halved, as measured with the Freiburg Vision Test (FrACT), yet patients are happy.

BACKGROUND: As the desire for spectacle independence following cataract surgery grows, so does interest in the implantation of multifocal intraocular lenses. However, glare phenomena, reduced intermediate vision and loss of image quality are known problems associated with this new generation of lenses. We compared the functional results achieved by the implantation of the diffractive-refractive Acri.LISA 366D lenses to those achieved from implanting monofocal Acri.Smart 46LC lenses. METHODS: In a retrospective data analysis we followed ten patients who received bifocal intraocular lenses (Acri.LISA 366D) and ten patients who received monofocal intraocular lenses (Acri.Smart 46LC). Lenses were always implanted in both eyes. In each group we assessed visual acuity and contrast sensitivity with the Freiburg Vison Test (FrACT) at multiple distances ranging from 0.5 to 5 m. Additionally, we assessed near vision with the Birkhaeuser charts. We also evaluated photopic phenomena and patient satisfaction using a standardised questionnaire. One patient in the Acri.LISA group and six patients in the control group missed the recommended follow-up visits. RESULTS: We found good uncorrected distance and near visual acuity. Only three of nine patients wore glasses occasionally. Although their contrast sensitivity decreased by a factor of two compared to the control group, patients did not complain about visual disturbances. Patient satisfaction was predominantly high following Acri.LISA 366D implantation. CONCLUSIONS: With the Acri.LISA 366D, patients demonstrate excellent near and distance vision, albeit with reduced contrast sensitivity. Acri Lisa is a viable option in patients that do not want to depend on spectacles.

Clinical results of 123 femtosecond laser-assisted penetrating keratoplasties.

BACKGROUND: Postoperative astigmatism following penetrating keratoplasty is a major problem after corneal transplantation. The main goal of new trephination techniques such as femtosecond laser or excimer-laser trephination is to improve refractive and visual outcomes. The femtosecond laser technique makes profiled corneal trephinations such as the top hat or mushroom profile possible. We present the postoperative outcome of femtosecond laser-assisted penetrating keratoplasties. METHODS: We performed 123 femtosecond laser-assisted penetrating keratoplasties in 119 patients. The main outcome measures were intraoperative specifics, astigmatism, and irregularity in Orbscan corneal topography, as well as the occurrence of immune reactions and side-effects. RESULTS: All sutures have been removed in 49 of these 123 eyes. Their mean follow-up was 13.9 ± 4.5 months. Time to complete suture removal (n = 49) was 12.0 ± 3.7 months in the mushroom group and 9.8 ± 2.1 months in the top hat group. Mean astigmatism in Orbscan topography was 6.4 ± 3.0 diopters in the mushroom and 5.8 ± 4.6 diopters in the top hat group (all sutures out). CONCLUSIONS: Femtosecond laser-assisted penetrating keratoplasty is a safe surgical technique. Due to the steps in profiled trephinations, the wound area is larger and theoretically the wound healing is, thus, faster and more stable. Complete suture removal is possible at an earlier time point compared to conventional penetrating keratoplasty. However, refractive results are not superior to those following conventional trephination.

Allogenic limbo-keratoplasty with conjunctivoplasty, mitomycin C, and amniotic membrane for bilateral limbal stem cell deficiency.

OBJECTIVE: To present the technique and report the results of up to 36 months after allogenic central penetrating limbo-keratoplasty in conjunction with conjunctivoplasty, mitomycin C (MMC), and amniotic membrane (AM) transplantation in patients with bilateral limbal stem cell deficiency (LSCD). DESIGN: Retrospective, consecutive subject cohort study. PARTICIPANTS: Case records of 20 eyes from 20 patients who presented with bilateral LSCD due to aniridia, chemical/thermal burn, cicatrizing pemphigoid, and chronic ocular surface inflammation and who were treated at the University Eye Hospital, Freiburg. METHODS: All eyes were treated with central limbo-keratoplasty in conjunction with conjunctivoplasty, MMC, and AM. There were 20 human leukocyte antigen-typed allolimbal transplants from cadaveric donors. All patients received systemic immunosuppression with mycophenolate mofetil or cyclosporine A. MAIN OUTCOME MEASURES: Surgical success was measured by the duration for which a healthy corneal epithelium was maintained. Visual success was measured by an improvement in visual acuity (VA) in the eye during follow-up and directly correlated with central clear graft survival. RESULTS: The follow-up period was up to 34 months (mean, 20 months; median, 22.4 months). Mean VA, measured in decimal fractions, increased from 0.029 (∼20/400; median, 0.005; first quartile 0.005; third quartile 0.005) before surgery to 0.281 (20/70; median, 0.2; first quartile 0.04; third quartile 0.55) after surgery. Healthy corneal epithelium showing survival of limbal stem cells was observed in 14 eyes (70%) during complete follow-up. CONCLUSIONS: Penetrating limbo-keratoplasty with conjunctivoplasty, MMC, and AM transplantation is a promising new surgical technique for improving vision and conjunctivalization in patients with severe bilateral LSCD necessitating allogenic transplants.

Operational post-keratopasty graft tolerance due to differential HLAMatchmaker matching.

PURPOSE: Penetrating keratoplasty can restore vision in corneal blindness. However, immunologic rejection threatens graft survival. Matching donors at swine leukocyte antigen (SLA)-class II convey allo-specific tolerance in a large animal kidney-transplantation model despite mismatches at SLA-class I. The same matching pattern seems to account for the blood transfusion effect in kidney transplantation. Relying on the molecular basis of HLAMatchmaker eplets, we assessed whether this finding would also apply to keratoplasty, and if it would enhance the benefit from matching human leukocyte antigen (HLA)-class I alone. METHODS: We retrospectively selected two independent cohorts comprising 586 and 975 penetrating keratoplasties. Our computations revealed a quantitative tolerogenicity factor analogous to the animal model. The number of mismatched HLA-class I eplets functioned as a factor for conventional histocompatibility. In the first cohort, we empirically determined the thresholds with the highest predictive power on graft rejection for both factors, and confirmed those thresholds in the second cohort. We applied Cox proportional hazards regression for these analyses. RESULTS: The thresholds with highest predictive power revealed 220 eplets(2) for the tolerance factor and 10 eplets for HLA-class I histocompatibility. The respective hazards ratios were 2.22 (p=0.04) versus 3.63 (p<0.01) in the first cohort and 2.09 (p<0.01) versus 1.51 (p=0.02) in the second, confirmatory cohort. The threshold factors proved to be additive in predicting immune reactions in both cohorts, (hazard ratios 2.66 in cohort 1 versus 1.70; p<0.01 in cohort 2). CONCLUSIONS: Operational tolerance may be inducible by balanced matching of HLA-class I and II HLAMatchmaker eplets. Furthermore, such tolerance is additive to histocompatibility at HLA-class I.

NK cell depletion delays corneal allograft rejection in baby rats.

PURPOSE: Penetrating keratoplasty has a very poor outcome compared with adults if performed in the first years of life. Rejection in these young patients occurs even in the absence of known immunological risk factors. Recently, a baby rat model was introduced and an essential contribution of natural killer (NK) cells during allograft rejection was suggested. To analyze this, NK cells were depleted in baby rats before keratoplasty. METHODS: Allogeneic keratoplasty was performed between Lewis and Fisher rats. The recipient's ages were 10 and 3 weeks, respectively. NK cells were depleted by an intraperitoneal injection of a monoclonal antibody. All experiments were controlled by the injection of isotypic control antibodies and syngeneically. Survival rates were calculated and cellular infiltrates were analyzed histologically. RESULTS: NK cell depletion did delay median graft survival times in a statistically significantly way compared with the control animals (p<0.01). At median rejection time points, macrophages, CD4(+) T cells and CD25(+) leukocytes infiltrated to a greater extent in the depleted recipients. No significant changes in the cell numbers of infiltrating CD8(+) T cells were observed. CONCLUSIONS: We conclude that NK cells play a role during allograft rejection in baby rats, but their effect is replaceable. A greater infiltration of macrophages and CD4(+) T cells suggests that they might compensate for the missing NK cells' response in this experimental setting. Our results represent another step toward understanding the complex mechanisms of an accelerated corneal graft rejection in infant recipients.

Successful treatment of cystoid macular edema with valdecoxib.

PURPOSE: To evaluate the safety and efficacy of the COX-2 inhibitor valdecoxib in treating macular edema after cataract surgery. SETTING: University Eye Clinic, Freiburg, Germany and Reis Medical Institution, Liechtenstein. METHODS: The COX-2 inhibitor valdecoxib (Bextra) was administered systemically to patients with significant visual loss resulting from macular edema in a prospective clinical trial. RESULTS: Ten patients were enrolled. Valdecoxib was tolerated well and led to a significant visual improvement within 10 days of therapy in all patients. CONCLUSION: The fast and persistent control of macular edema with valdecoxib warrants further investigation.

An open prospective pilot study on the use of rapamycin after penetrating high-risk keratoplasty.

BACKGROUND: The purpose of this study was to prove efficacy and safety of systemic immunosuppression with rapamycin following penetrating high-risk keratoplasty. Rapamycin has shown its immunosuppressive potential in the rat keratoplasty model and is a component of several immunosuppressive protocols after solid organ transplantation. In this pilot study, we compared the efficacy and safety of rapamycin and mycophenolate mofetil (MMF). METHODS: Ten patients (group 1) undergoing high-risk keratoplasty were included in this study, receiving rapamycin as postoperative immunoprophylaxis. Rapamycin was administered orally once daily (blood trough level 4-10 ng/ml) for 6 months. Thereafter, it was tapered over 2 weeks. The control group (group 2) consisted of 24 patients who received 1000 mg MMF twice daily for 6 months. All of the patients received postoperative medication with fluocortolone 1 mg/kg/day (tapered over 3 weeks) and prednisolone acetate eyedrops 5 times per day (tapered over 5 months). RESULTS: Mean follow-up of all patients (n=34) was 739 days. No immune reaction was observed in groups 1 and 2 during the first 6 months under immunosuppression. Two immune reactions occurred in group 1, and five in group 2 within a 2-year follow-up. All of the immune reactions were reversible. The side effects observed in both groups were mostly reversible. CONCLUSIONS: Rapamycin and mycophenolate mofetil seem to be similarly efficacious in preventing immune reactions after high-risk keratoplasty, as long as they are administered. However, we observed a broad spectrum of side effects from rapamycin.

Long-term follow-up of astigmatic keratotomy for corneal astigmatism after penetrating keratoplasty.

PURPOSE: To report the long-term stability of paired arcuate corneal keratotomies (AKs) in patients with high regular postpenetrating keratoplasty astigmatism. METHODS: Retrospective chart review of best-corrected visual acuity, refraction and keratometric values of 41 eyes with AK between 2003 and 2012. RESULTS: Magnitude of median target induced astigmatism vector was 9.2 dioptres (Dpt). We reached a median magnitude of surgically induced astigmatism vector of 9.81 Dpt and a median magnitude of difference vector of 5.5 Dpt. In keratometry, we achieved a net median astigmatism reduction by 3.3 Dpt. The average correction index was 1.14, showing a slight overcorrection. Irregularity of keratometric astigmatism increased by 0.6 Dpt, and spherical equivalent changed by 1.75 Dpt. Monocular best spectacle corrected visual acuity increased from preoperatively 20/63 (0.5 logMAR) to 20/40 (0.3 logMAR) postoperatively. Median gain on the ETDRS chart was two lines. Long-term follow-up showed a median keratometric astigmatic increase by 0.3 Dpt per year. CONCLUSION: Arcuate corneal keratotomies is a safe and effective method to reduce high regular corneal astigmatism following penetrating keratoplasty but has limited predictability. The long-term follow-up shows an increase of keratometric astigmatism by 0.3 Dpt/year, equalizing the surgical effect after 10 years.

Comparison of Long-Term Outcomes of Femtosecond Laser-Assisted Keratoplasty with Conventional Keratoplasty.

PURPOSE: Astigmatism is a significant problem in penetrating keratoplasty. Lower astigmatism and better visual outcomes had been expected from laser-assisted penetrating keratoplasty, that is, from the top-hat, mushroom, or zig-zag cutting profiles. We report the long-term outcomes of 141 femtosecond laser-assisted penetrating keratoplasties retrospectively. We compare these outcomes with those of penetrating keratoplasty using the guided trephine system (GTS). METHODS: In all, 141 femtosecond laser-assisted penetrating keratoplasties had been performed in 119 patients. The results were compared with those of conventional keratoplasty (n = 1254; visual and refractive outcomes, graft rejections, and graft failure). RESULTS: Follow-up averaged 33 months. In eyes with keratoconus, the time to achieve a visual acuity of 10/20 (Snellen) was shorter in the mushroom than in the GTS group. However, there was no relevant long-term difference. Graft astigmatism was higher in the laser groups [keratometric astigmatism at the end of follow-up: -4.5 ± 4 (GTS), -5.8 ± 3.3 (top-hat), -5.9 ± 3.2 D (mushroom); P < 0.01]. In eyes with keratoconus, rates of graft rejection were highest in the mushroom group (55%). In the other groups, top-hat keratoplasty resulted in lower rates of rejection than GTS keratoplasty (31%). CONCLUSIONS: There is no significant difference in the refractive and visual outcomes after femtosecond laser-assisted penetrating keratoplasty compared with GTS keratoplasty. The benefits from the use of the femtosecond laser may be limited and should be weighed against an increased risk of immune reactions, higher surgical complexity, and higher costs.

Immunosuppression with cyclosporine A and mycophenolate mofetil after penetrating high-risk keratoplasty: a retrospective study.

BACKGROUND: Graft-prognosis after penetrating high-risk keratoplasty has improved considerably with the use of systemic immunosuppressive medications. In this retrospective investigation we analyzed the long-term results of 417 high-risk keratoplasties with systemic immunosuppression (cyclosporine A [CsA] or mycophenolate mofetil [MMF]). METHODS: A total of 417 high-risk keratoplasties with postoperative systemic immunosuppression were evaluated retrospectively: CsA has been given in 252 keratoplasties since 1987, aiming at blood trough levels of 120 to 150 ng/mL. Systemic MMF at a daily dose of 2 x 1 g was administered in 149 surgical procedures. After 16 high-risk keratoplasties, combined systemic immunosuppression with CsA and MMF was administered. Systemic immunosuppression was scheduled for 6 to 12 months. All patients received fluocortolone 1 mg/kg body weight per day, tapered over 3 weeks, and topical prednisolone acetate 1%, tapered over 5 months. RESULTS: Rejection-free graft survival after 1 year was 75% in the CsA group and 89% in the MMF group; 60% of the grafts in the CsA group and 72% of the grafts in the MMF group were rejection-free 3 years postoperatively (Kaplan-Meier log-rank test P=0.03). Clear graft survival after 1 and 3 years was 92% and 77% (CsA) and 96% and 87% (MMF), respectively. The MMF-treated patients showed fewer side effects than the CsA-treated patients. The side effects attributable to both drugs were reversible. CONCLUSIONS: We found a statistically significant, stronger effect of MMF compared with CsA in preventing immune reactions after high-risk keratoplasty, despite a shorter MMF administration compared with CsA. Both systemic immunosuppressants were shown to have comparable potency regarding clear graft survival and were well tolerated.

Cyclooxygenase-2 inhibitors: a new therapeutic option in the treatment of macular edema after cataract surgery.

Two patients had uneventful phacoemulsification. After initial improvement, vision deteriorated because of cystoid macular edema (CME). In 1 patient, treatment with systemic nonsteroidal antiinflammatory drugs showed significant improvement in visual acuity but had to be discontinued because of side effects and a relapse of the disease. In the other patient, this therapy was not sufficient. Both patients were given valdecoxib, a cyclooxygenase-2 inhibitor. The new therapy was tolerated well and led to significant and stable improvement in visual acuity in both patients. To our knowledge, this is the first report of using a cyclooxygenase-2 inhibitor in the treatment of clinically significant CME.

Improved wound stability of top-hat profiled femtosecond laser-assisted penetrating keratoplasty in vitro.

PURPOSE: The femtosecond laser is a new option for cutting corneal tissue at high precision. The "top-hat" profile has an overlapping graft-host interface at the edge because of a larger inner trephination diameter. This may enhance graft fixation, thus improving the outcome and accelerating rehabilitation after penetrating keratoplasty. METHODS: Femtosecond laser top-hat keratoplasties with overlaps of 0 and 3 mm between inner and outer trephination diameters were performed in vitro. After trephination, the excised corneal buttons were readapted by different suturing profiles. Pressure in the artificial anterior chamber was then raised until we observed wound leakage and ultimately wound prolapse. RESULTS: Better wound stability was found in conjunction with all profiled trephinations. When using 4 interrupted sutures, wound leakage occurred at a median of 13.0 cm H2O (mean, 12.3 cm H2O) and "zero overlap," at 19.0 cm H2O (mean, 20.8 cm H2O) and 1-mm overlap, at 32.0 cm H2O (mean, 32.8 cm H2O) and 2-mm overlap, and at 48.5 cm H2O (mean, 49.4 cm H2O) and 3-mm overlap. Comparing zero overlap with the mean values of 1- to 3-mm overlaps, wound leakage happened at 13.0 (mean, 12.3) versus 32.0 (mean, 34.3) cm H2O with 4 interrupted sutures, at 57.5 (mean, 58.3) versus 61.0 (mean, 70.8) cm H2O with 8 interrupted sutures, at 31.5 (mean, 32.0) versus >97.0 (mean, 75.5) cm H2O with 1 running and 4 interrupted sutures, and at 34.0 (mean, 32.3) versus 80.0 (mean, 69.9) cm H2O with 1 running suture. The analysis of variance revealed a statistically significant increase in wound stability for all overlaps independently from the size of the overlap. CONCLUSIONS: Femtosecond laser-assisted profiles with even small overlaps for penetrating keratoplasty may make fewer sutures and earlier suture removal possible because of better wound stability, contributing to earlier visual recovery and helping to prevent wound rupture after trauma. However, further study is required to identify the optimum profile including the various technical parameters.

The intrastromal corneal ring in penetrating keratoplasty-long-term results of a prospective randomized study.

PURPOSE: Postoperative astigmatism after penetrating keratoplasty is a major problem in corneal transplantation. The purpose of this prospective randomized study was to evaluate the efficacy and safety of an intrastromal corneal ring after penetrating keratoplasty. METHODS: Twenty patients were included, 10 of whom received an intracorneal ring (group 1) and 10 who did not (group 2, control group). Astigmatism in Orbscan corneal topography, occurrence of immune reactions, and occurrence of side effects were this study's main outcome criteria. RESULTS: Mean follow-up time was 27.6 ± 5.3 months. Mean astigmatism (Orbscan) was 4.4 diopters in group 1 and 4.4 diopters in group 2 (P = 0.695). Spontaneous suture rupture occurred in 5 patients with corneal ring but in none of those in the control group. We observed 3 immune reactions in 3 patients with corneal ring, whereas group 2 experienced no rejection (P < 0.05). Endothelial cell loss was 15.1% in the group with the ring and 8.7% in the control group. That difference was not statistically significant (P = 0.146). CONCLUSIONS: The use of the intrastromal corneal ring after penetrating keratoplasty caused no reduction in postoperative astigmatism. However, its use was statistically significantly associated with adverse events.

Accelerated corneal graft rejection in baby rats.

BACKGROUND: Penetrating keratoplasty in infants has a very poor outcome compared to adults. It is of intrinsic interest to gain insight into the still unknown immunological mechanisms of graft failure because any form of uncorrected corneal opacity leads to amblyopia. METHODS: Allogeneic keratoplasty was performed between Lewis and Fisher rats. The recipients' ages were 10 and 3 weeks, respectively. All experiments were controlled syngeneically. Survival rates were calculated and cellular infiltrates analysed histologically. RESULTS: Median graft survival times were 15 days in old recipients and 9 days in young recipients (p<0.01). There were fewer infiltrating cells in the younger rats than in the older ones on the day of rejection. Despite the fact that T cells dominated there were significantly more NK cells in young recipients at all time points after transplantation when compared to old recipients. CONCLUSIONS: An animal model has been established that shows similar rejection kinetics as in children, that is corneal graft failure occurs sooner in young rats. Already little infiltration was sufficient to reject a corneal allograft. The dominance of infiltrating NK cells and the vigorous rejection process suggest an involvement of the innate immune system in this process.

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.

Toxic anterior segment syndrome following penetrating keratoplasty.

OBJECTIVES: To describe an outbreak of toxic anterior segment syndrome (TASS) following penetrating keratoplasty (PK) and to examine its possible causes. METHODS: Owing to a series of TASS following PK between June 6, 2007, and October 2, 2007, we reviewed the records of all patients who had undergone PK during that time. In addition to routine microbial tests on organ culture media, we looked for specific pathogens and endotoxins in all of the materials used for organ culture or PK. Furthermore, we analyzed all of the perioperative products and instrument processing. RESULTS: Of the 94 patients who underwent PK, we observed 24 cases of postoperative sterile keratitis. Causal research revealed that the accumulation of cleaning substances or heat-stable endotoxins on the surface of the routinely used guided trephine system was most likely responsible for the TASS. CONCLUSIONS: To our knowledge, this is the first report on TASS following PK. Suboptimal reprocessing of surgical instruments may be an important cause of TASS as in this series the TASS-like symptoms resolved after modified instrument-cleaning procedures. The standardization of protocols for processing reusable trephine systems might prevent outbreaks of TASS following PK.

Topical pimecrolimus does not prolong clear graft survival in a rat keratoplasty model.

BACKGROUND: Long-term application of topical steroids following penetrating keratoplasty is disadvantageous due to side effects (steroid response, cataract, surface disorders). In this study we investigated the efficacy of topical pimecrolimus regarding clear graft survival following allogeneic orthotopic keratoplasty in rats. METHODS: A total of 46 penetrating keratoplasties were performed using Fisher rats (allogeneic groups) and Lewis rats (syngeneic group) as donors and Lewis rats as recipients: group 1 (n = 11), allogeneic control without therapy; group 2 (n = 12), syngeneic control; group 3 (n = 11), mycophenolate mofetil (MMF) 40 mg/kg body weight; group 4 (n = 12), pimecrolimus 1% ointment twice daily. Four animals of each group were sacrificed for immunohistological evaluation on day 14. Therapy was administered for 18 days. The grafts were evaluated once every 3 days regarding opacity, oedema and vascularisation. Graft rejection was defined as total graft opacity. RESULTS: Mean rejection-free graft survival was 11.4 days in group 1 (allogeneic control), 100 days (total follow-up time) in group 2 (syngeneic control), 24.0 days in group 3 (MMF 40 mg/kg) and 11.6 days in group 4 (topical pimecrolimus). The immunohistological evaluation showed no statistically significant difference in cell infiltration of the grafts comparing groups 1 and 4. CONCLUSIONS: Topical immunosuppression with pimecrolimus does not prolong graft survival in the allogeneic keratoplasty rat model.

Endothelial cell loss after autologous rotational keratoplasty.

PURPOSE: To investigate whether it may be possible to ascertain the influence of immunological factors on chronic endothelial cell loss by comparing chronic endothelial cell loss after autologous rotational penetrating keratoplasty and after homologous penetrating keratoplasty. METHODS: For six patients who had undergone autologous rotational penetrating keratoplasty the relative annual loss of endothelial cells was calculated by means of an exponential regression analysis. The findings were compared with those in a homogeneous historical control group (53 patients undergoing homologous penetrating keratoplasty for keratoconus). RESULTS: After autologous rotational keratoplasty relative annual loss of endothelial cells was 1.1%+/-2.6% (mean +/- standard deviation). Relative annual loss of endothelial cells in the control-group was 16.7%+/-20.8%. CONCLUSIONS: The results of the study lead to the assumption that immunological influences might be the main cause for chronic endothelial cell loss after homologous penetrating keratoplasty.