The effect of ABO blood incompatibility on corneal transplant failure in conditions with low-risk of graft rejection

Management and prevention of corneal graft rejection

The management of an episode of corneal graft rejection (CGR) is primarily by corticosteroids. Immunomodulators are useful for long-term immunosuppression and in dealing with cases of high-risk (HR) corneal grafts. The classical signs of CGR following penetrating keratoplasty (PKP) include rejection line, anterior chamber (AC) reaction, and graft edema. However, these signs may be absent or subtle in cases of endothelial keratoplasty (EK). Prevention of an episode of graft rejection is of utmost importance as it can reduce the need for donor cornea significantly. In our previous article (IJO_2866_22), we had discussed about the immunopathogenesis of CGR. In this review article, we aim to discuss the various clinical aspects and management of CGR.

Long-term Outcomes After Lamellar Endothelial Keratoplasty Compared With Penetrating Keratoplasty for Corneal Endothelial Dysfunction: A Systematic Review

PURPOSE

The purpose of this study is to evaluate long-term outcomes of endothelial keratoplasty (EK) compared with penetrating keratoplasty (PK) for corneal endothelial dysfunction [Fuchs endothelial corneal dystrophy (FECD) and bullous keratopathy (BK)].

METHODS

In this systematic review, we searched PubMed, the Cochrane Library, and Embase up to May 2022 and considered all types of studies addressing our objective. Graft survival at 5, 10, and 15 years was the main outcome.

RESULTS

Fifty cohort studies were included. At 5 years, in FECD and BK, graft survival seemed higher after EK than PK. Two comparative studies showed either a higher 5-year graft survival after EK than PK or no significant differences. Including noncomparative studies, in FECD, the 5-year graft survival ranged from 0.69 to 0.98 for PK, from 0.93 to 1.00 for DSEK, and from 0.93 to 0.99 for Descemet membrane endothelial keratoplasty (DMEK). In BK, the 5-year graft survival ranged from 0.39 to 0.91 for PK, from 0.65 to 0.89 for DSEK, and from 0.84 to 0.95 for DMEK. The 10-year graft survival ranged from 0.20 to 0.90 for PK and from 0.62 to 0.92 for EK. The mean 5-year best spectacle-corrected visual acuity ranged from 0.73 to 0.43 LogMAR for PK, from 0.61 to 0.09 for DSEK, and from 0.31 to 0.05 for DMEK. The 5-year rejection rate ranged from 11.0% to 28.7% for PK, from 5.0% to 7.9% for DSEK, and from 1.7% to 2.6% for DMEK.

CONCLUSIONS

These results suggest a higher 5-year graft survival and better secondary outcomes after EK. Nevertheless, the level of evidence was low.

PROSPERO REGISTRATION

CRD42021260614.

Endothelial failure and rejection in recipients of corneas from the same donor

Objective

To determine whether patients who receive corneas from the same donor have similar risks of endothelial failure and rejection.

Methods and Analysis

Patients with Fuchs endothelial dystrophy (FED) and pseudophakic bullous keratopathy (PBK) who received their first corneal transplant between 1999 and 2016 were analysed. Patients receiving corneas from donors who donated both corneas for the same indication were defined as ‘paired’. Gray’s test was used to compare the cumulative incidence of endothelial failure and rejection within 5 years post-transplant for ‘paired’ and ‘unpaired’ groups. Cox regression models were fitted to determine whether there was an association between recorded donor characteristics (endothelial cell density (ECD), age and sex and endothelial graft failure and rejection.

Results

10 838 patients were analysed of whom 1536 (14%) were paired. The unpaired group comprised 1837 (69%) recipients of single corneal donors and 7465 (69%) donors who donated both corneas for another indication. ECD was lower for unpaired single cornea donors (p<0.01). There was no significant difference in endothelial graft failure or rejection between paired and unpaired groups for FED (p=0.37, p=0.99) or PBK (p=0.88, p=0.28) nor for donor ECD, age, sex and paired donation after adjusting for transplant factors (across all models p>0.16 for ECD, p>0.32 for donor age, p>0.14 for sex match and p>0.17 for the donor effect).

Conclusion

The absence of a significant difference in graft outcome for corneal transplants for FED and PBK between paired and unpaired donors may reflect a homogeneous donor pool in the UK.

Risk factors of rejection after penetrating keratoplasty: a retrospective monocentric study

PURPOSE

To assess risk factors of rejection after penetrating keratoplasty (PKP).

METHODS

This retrospective monocentric study assessed risk factors for rejection in patients who underwent PKP at Montpellier University Hospital between June 2005 and September 2018. Graft and donor data were obtained from our tissue bank in Montpellier. Clinical data of recipients were recorded from medical files. Survival was estimated by the Kaplan-Meir method. Potential risk factors of rejection were assessed by multivariate Cox proportional hazards analysis, estimating hazard ratios (HR) and 95% confidence intervals (CI).

RESULTS

Among the 316 consecutive patients (59% male, mean SD] age 52 [17]), 360 eyes underwent PKP. Indications for PKP were bullous keratopathy (27%), infectious keratitis (20%), and keratoconus (15%). The median follow-up was 44 months (IQR 22-73). The overall graft survival and irreversible rejection rate at 5 years were 70% and 29%, respectively. Factors associated with risk of rejection were prior indication for graft rejection (SHR [CI 95%] = 7.8 [2.6-23.1]), trauma (SHR [CI 95%] = 3.6 [1.1-11.7]), and infectious keratitis (SHR [CI 95%] = 2.7 [1.2-11.1]), history of corneal neovascularization (SHR [CI 95%] = 2.1 [1.2-3.8]), hypertonia (SHR [CI 95%] = 2.8 [1.8-4.3]), and mixed sex matching (SHR [CI 95%] = 2.0 [1.01-4.0]).

CONCLUSION

The significant risk factors of graft rejection after PKP found in this study agree with those from major international cohorts: prior indication for graft rejection, history of neovascularization and high intraocular pressure. Sex matching donor-recipient is a most recent parameter in the literature confirmed by the present analysis.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04791696.

Corneal Donation: Current Guidelines and Future Direction

PURPOSE

This review aims to outline current practices and guidelines of corneal donation and eye banking, describes the implications of COVID-19 and emerging diseases on the corneal donor pool, and discusses future trends to improve and increase the efficiency of the processes involved in corneal donation and eye banking.

SUMMARY

Corneal screening, preservation, corneal storage, and prevention of systemic disease transmission from donor to recipient have been crucial in shaping the policies of the FDA and eye banks across the world. Eye banks globally have developed varying guidelines and criteria for evaluating the viability of donor corneas. Variables such as the age of the donor, medical history, and potential disease transmission are important screening parameters. While known infectious diseases may be transmissible through the cornea, emerging infectious diseases that are not well studied may be more transmissible than other infections. In particular, coronavirus has impacted corneal transplantation as SARS-CoV-2 expression has been detected in corneal tissue and conjunctiva. In recent years, partial-thickness corneal transplantations have been introduced. Lamellar grafts and other corneal layers are now utilized for transplantation of the specific areas that are damaged.

Corneal graft failure: an update

Corneal graft surgery is one of the most successful forms of human solid-tissue transplantation, and nowadays, there is a worldwide expansion of the surgical volume of corneal grafts. This surgery is continuously evolving, with new surgical techniques and postoperative treatments that have considerably increased the chance of survival for the grafts. Despite the high rate of success, corneal transplantation is still complicated by a relevant risk of graft failure. This study investigates the causes that lead to the failure of the different corneal graft surgical techniques and provides an updated synthesis on this topic. A comprehensive review of the main pathological pathways that determine the failure of corneal grafts is provided, analysing the main risk factors and disclosing the survival rates of the principal form of corneal grafts. Our results revealed that penetrating keratoplasty has higher failure rates than lamellar keratoplasty, with immunological rejection being the leading cause of graft failure, followed by late endothelial failure (LEF) and ocular surface disorders. Postoperative glaucoma and dehiscence of the surgical wound represent other important causes of failure. Endothelial keratoplasty showed the lowest rates of failure in the mid-term, with LEF, detachment of the graft and primary graft failure representing the most common pathological reasons for failure.

The Influence of Donor and Recipient Gender Incompatibility on Corneal Transplant Rejection and Failure

In vascularized organ transplants, gender mismatches have higher rates of immunological rejection. We investigated the influence of gender incompatibility, including H-Y incompatibility, on corneal transplant graft rejection and failure. Patients were included who had undergone a first corneal transplant for keratoconus (KC), Fuchs endothelial dystrophy (FED), pseudophakic bullous keratopathy (PBK), infection and other indications. A Cox regression model was fitted for each indication to determine factors affecting graft failure and rejection at 5 years. The impact of gender, including H-Y, matching was analyzed after accounting for other factors, including known risk factors. Of 18 171 patients, 4314 had undergone a transplant for FED, 4783 for KC, 3669 for PBK, 1903 for infection and 3502 for other disorders. H-Y mismatched (male [M]→female [F]) corneas were at greater risk of graft failure or rejection. For FED, F→F were 40% less likely to fail (p < 0.0001) and 30% less likely to reject (p = 0.01); M→M were 20% less likely to fail (p = 0.04) and 30% less likely to reject (p = 0.01). For KC, M→M matched corneas were 30% less likely to fail (p = 0.05) and 20% less likely to reject (p = 0.01) compared with H-Y mismatches. H-Y antigen mismatched (M→F) patients were at greater risk of rejection or graft failure.

High-risk corneal allografts: A therapeutic challenge

Corneal transplantation is the most common surgical procedure amongst solid organ transplants with a high survival rate of 86% at 1-year post-grafting. This high success rate has been attributed to the immune privilege of the eye. However, mechanisms originally thought to promote immune privilege, such as the lack of antigen presenting cells and vessels in the cornea, are challenged by recent studies. Nevertheless, the immunological and physiological features of the cornea promoting a relatively weak alloimmune response is likely responsible for the high survival rate in “low-risk” settings. Furthermore, although corneal graft survival in “low-risk” recipients is favourable, the prognosis in “high-risk” recipients for corneal graft is poor. In “high-risk” grafts, the process of indirect allorecognition is accelerated by the enhanced innate and adaptive immune responses due to pre-existing inflammation and neovascularization of the host bed. This leads to the irreversible rejection of the allograft and ultimately graft failure. Many therapeutic measures are being tested in pre-clinical and clinical studies to counter the immunological challenge of “high-risk” recipients. Despite the prevailing dogma, recent data suggest that tissue matching together with use of systemic immunosuppression may increase the likelihood of graft acceptance in “high-risk” recipients. However, immunosuppressive drugs are accompanied with intolerance/side effects and toxicity, and therefore, novel cell-based therapies are in development which target host immune cells and restore immune homeostasis without significant side effect of treatment. In addition, developments in regenerative medicine may be able to solve both important short comings of allotransplantation: (1) graft rejection and ultimate graft failure; and (2) the lack of suitable donor corneas. The advances in technology and research indicate that wider therapeutic choices for patients may be available to address the worldwide problem of corneal blindness in both “low-risk” and “high-risk” hosts.

[Risk factors, clinical presentations, prevention, and treatment of corneal graft rejection]

Corneal transplantation is the most common and successful type of allotransplantation surgery. Post-transplant immune response in keratoplasty is less pronounced than that in other transplantation procedures, which is accounted for by anatomical features of the cornea and, also, its low antigenic potential and active immunosuppression. However, the immune privilege of the cornea can be violated by neovascularization, inflammation, or trauma. Patients who require keratoplasty to restore their sight and whose immune privilege is disturbed, fall into a high-risk group and are likely to demonstrate tissue incompatibility and non-transparent engraftment. Two approaches exist as to how graft rejection can be prevented. One of them involves induction of donor-specific tolerance, the other - non-specific suppression of the recipient's immune response. To avoid tissue incompatibility, measures can be taken to restore the immune privilege of the cornea as well as to induce antigen-specific tolerance, which is considered a promising, thought yet experimental, area of modern transplantology. In clinical practice, one pays most attention to improvement of non-specific immune suppression methods based on interfering in the metabolism of immunocompetent cells. Thus, timely prescriptions and proper immunosuppressive tactics with account to possible risk factors determine the outcome in high-risk patients undergoing corneal transplantation surgery.

Factors associated with corneal graft survival in the cornea donor study

IMPORTANCE

The Cornea Donor Study (CDS) showed that donor age is not a factor in survival of most penetrating keratoplasties for endothelial disease. Secondary analyses confirm the importance of surgical indication and presence of glaucoma in outcomes at 10 years.

OBJECTIVE

To assess the relationship between donor and recipient factors and corneal graft survival in the CDS.

DESIGN, SETTING, AND PARTICIPANTS

Multicenter prospective, double-masked, controlled clinical trial conducted at 80 clinical sites. One hundred five surgeons enrolled 1090 participants undergoing corneal transplant for a moderate-risk condition, principally Fuchs dystrophy or pseudophakic or aphakic corneal edema (PACE). Forty-three eye banks provided corneas.

INTERVENTIONS

Corneas from donors younger than 66 years and donors 66 years or older were assigned, masked to donor age. Surgery and postoperative care were performed according to the surgeons' usual routines. Participants were followed up for as long as 12 years.

MAIN OUTCOMES AND MEASURES

Graft failure, defined as a regrafting procedure or a cloudy cornea for 3 consecutive months.

RESULTS

The 10-year cumulative probability of graft failure was higher in participants with PACE than in those with Fuchs dystrophy (37% vs 20%; hazard ratio [HR], 2.1 [99% CI, 1.4-3.0]; P < .001) and in participants with a history of glaucoma before penetrating keratoplasty, particularly with prior glaucoma surgery (58% with prior glaucoma surgery and use of medications to lower intraocular pressure at the time of surgery vs 22% with no history of glaucoma surgery or medication use; HR, 4.1 [99% CI, 2.2-7.5]; P < .001). We found trends toward increased graft failure in recipients who were 70 years or older compared with those younger than 60 years (29% vs 19%; HR, 1.2 [99% CI, 0.7-2.1]; P = .04) or were African American (HR, 1.5; P = .11) or who had a history of smoking (35% vs 24%; HR, 1.6 [99% CI, 0.9-2.8]; P = .02). Lower endothelial cell density (ECD) and higher corneal thickness (CT) at 6 months (6% vs 41% for ECD ≥2700 vs <1700 cells/mm2 [P < .001]; 14% vs 36% for CT <500 vs ≥600 μm [P = .001]), 1 year (4% vs 39% for ECD ≥2700 vs <1700 cells/mm2 [P < .001]; 18% vs 28% for CT <500 vs ≥600 μm [P = .04]), and 5 years (2% vs 29% for ECD ≥1500 vs <500 cells/mm2 [P < .001]; 7% vs 34% for CT <550 vs ≥650 μm [P < .001]) were associated with subsequent graft failure.

CONCLUSIONS AND RELEVANCE

Most penetrating corneal grafts for Fuchs dystrophy or PACE remain clear at 10 years. The risk for failure is greater for graft recipients with PACE and those with a history of glaucoma. Measurements of ECD and CT during the course of postkeratoplasty follow-up are associated with a risk for failure. However, even with very low ECD and high CT at 5 years, most corneas remain clear at 10 years.

Corneal graft rejection 10 years after penetrating keratoplasty in the cornea donor study

PURPOSE

The aim of this study was to assess the effect of donor and recipient factors on corneal allograft rejection and evaluate whether a rejection event was associated with graft failure.

METHODS

One thousand ninety subjects undergoing penetrating keratoplasty for a moderate risk condition (principally Fuchs dystrophy or pseudophakic corneal edema) were followed for up to 12 years. Associations of baseline recipient and donor factors with the occurrence of a rejection event were assessed in univariate and multivariate proportional hazards models.

RESULTS

Among 651 eyes with a surviving graft at 5 years, the 10-year graft failure (±99% confidence interval) rates were 12% ± 4% among eyes with no rejection events in the first 5 years, 17% ± 12% in eyes with at least 1 probable, but no definite rejection event, and 22% ± 20% in eyes with at least 1 definite rejection event. The only baseline factor significantly associated with a higher risk of definite graft rejection was a preoperative history of glaucoma, particularly when previous glaucoma surgery had been performed and glaucoma medications were being used at the time of transplant (10-year incidence 35% ± 23% compared with 14% ± 4% in eyes with no history of glaucoma/intraocular pressure treatment, P = 0.008).

CONCLUSIONS

Patients who experienced a definite rejection event frequently developed graft failure raising important questions as to how we might change acute and long-term corneal graft management. Multivariate analysis indicated that previous use of glaucoma medications and glaucoma filtering surgery was a significant risk factor related to a definite rejection event.

Matching for Human Leukocyte Antigens (HLA) in corneal transplantation - to do or not to do

As many patients with severe corneal disease are not even considered as candidates for a human graft due to their high risk of rejection, it is essential to find ways to reduce the chance of rejection. One of the options is proper matching of the cornea donor and recipient for the Human Leukocyte Antigens (HLA), a subject of much debate. Currently, patients receiving their first corneal allograft are hardly ever matched for HLA and even patients undergoing a regraft usually do not receive an HLA-matched graft. While anterior and posterior lamellar grafts are not immune to rejection, they are usually performed in low risk, non-vascularized cases. These are the cases in which the immune privilege due to the avascular status and active immune inhibition is still intact. Once broken due to infection, sensitization or trauma, rejection will occur. There is enough data to show that when proper DNA-based typing techniques are being used, even low risk perforating corneal transplantations benefit from matching for HLA Class I, and high risk cases from HLA Class I and probably Class II matching. Combining HLA class I and class II matching, or using the HLAMatchmaker could further improve the effect of HLA matching. However, new techniques could be applied to reduce the chance of rejection. Options are the local or systemic use of biologics, or gene therapy, aiming at preventing or suppressing immune responses. The goal of all these approaches should be to prevent a first rejection, as secondary grafts are usually at higher risk of complications including rejections than first grafts.

Endothelial morphometric measures to predict endothelial graft failure after penetrating keratoplasty

IMPORTANCE

Endothelial morphometric measures have potential value in predicting graft failure after penetrating keratoplasty.

OBJECTIVE

To determine whether preoperative and/or postoperative central morphometric measures (endothelial cell density [ECD], coefficient of variation [CV], and percentage of hexagonality [HEX]) and their postoperative changes are predictive of graft failure caused by endothelial decompensation after penetrating keratoplasty to treat a moderate-risk condition, principally Fuchs dystrophy or pseudophakic corneal edema.

DESIGN

In a subset of Cornea Donor Study participants with graft failure, a central reading center determined preoperative and postoperative ECD, CV, and HEX from available central endothelial specular images.

SETTING

Cornea Image Analysis Reading Center of the Specular Microscopy Ancillary Study.

PARTICIPANTS

Eighteen patients with graft failure due to endothelial decompensation and 54 individuals matched for most donor and recipient measures at baseline whose grafts did not fail.

MAIN OUTCOME MEASURE

Change in ECD, CV, and HEX values.

RESULTS

Preoperative ECD was not associated with graft failure (P = .43); however, a lower ECD at 6 months was predictive of subsequent failure (P = .004). Coefficient of variation at 6 months was not associated with graft failure in univariate (P = .91) or multivariate (P = .79) analyses. We found a suggestive trend of higher graft failure with lower HEX values at 6 months (P = .02) but not at the established statistical significance (P < .01). The most recent CV or HEX values, as time-dependent variables, were not associated with graft failure (P = .26 and P = .81, respectively). Endothelial cell density values decreased during follow-up, whereas CV and HEX appear to fluctuate without an apparent trend.

CONCLUSIONS AND RELEVANCE

Endothelial cell density at 6 months after penetrating keratoplasty is predictive of graft failure, whereas CV and HEX appear to fluctuate postoperatively, possibly indicating an unstable endothelial population in clear and failing grafts.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00006411.

Comparative cost-effectiveness analysis of descemet stripping automated endothelial keratoplasty versus penetrating keratoplasty in the United States

PURPOSE

To perform a comparative cost-effectiveness analysis of Descemet stripping automated endothelial keratoplasty (DSAEK) and penetrating keratoplasty (PK) for corneal endothelial disease.

DESIGN

Retrospective cost-effectiveness analysis.

METHODS

This cost-effectiveness analysis was performed from a third-party payer perspective with a 5-year time horizon. Probabilities of outcomes and complications of each of the procedures were calculated based on review of the published literature. A model was constructed to compare the costs and utilities associated with DSAEK and PK. Costs of donor tissue preparation, surgery, follow-up, postoperative complications, and procedures were considered. Utility values were based on quality-adjusted life years associated with visual acuity outcomes. Both costs and utilities were discounted at 3% per year. Sensitivity analyses were performed on key model inputs.

RESULTS

Base case analysis found DSAEK to be less costly compared with PK ($9362 vs $10 239), with greater utility (3.15 vs 2.47 quality-adjusted life years). Sensitivity analyses revealed that even at graft failure rates for DSAEK approaching the rates for PK, DSAEK would still reduce costs. Varying the dislocation rate in our model showed that even at dislocation rates approaching 50%, DSAEK remained less costly. Further, with DSAEK rejection rates as high as 28%, DSAEK would remain a dominant procedure over PK.

CONCLUSIONS

Comparative cost-effectiveness analysis of DSAEK versus PK indicates favorable cost and utility outcomes associated with DSAEK for treatment of corneal endothelial disease. Longer follow-up of DSAEK outcomes will provide more accurate information regarding long-term cost-effectiveness of the procedure.

Effect of donor and recipient factors on corneal graft rejection

PURPOSE

To assess the relationship between donor and recipient factors and corneal allograft rejection in eyes that underwent penetrating keratoplasty in the Cornea Donor Study.

METHODS

Overall, 1090 subjects undergoing corneal transplantation for a moderate risk condition (principally Fuchs dystrophy or pseudophakic corneal edema) were followed for up to 5 years. Associations of baseline recipient and donor factors with the occurrence of a probable or definite rejection event were assessed in univariate and multivariate proportional hazards models.

RESULTS

Eyes with pseudophakic or aphakic corneal edema (n = 369) were more likely to experience a rejection event than eyes with Fuchs dystrophy (n = 676) [34% ± 6% vs. 22% ± 4%; hazard ratio = 1.56; 95% confidence interval (CI), 1.21-2.03]. Among eyes with Fuchs dystrophy, a higher probability of a rejection event was observed in phakic posttransplant eyes compared with those that underwent cataract extraction with or without intraocular lens implantation during penetrating keratoplasty (29% vs. 19%; hazard ratio = 0.54; 95% CI, 0.36-0.82). Female recipients had a higher probability of a rejection event than male recipients (29% vs. 21%; hazard ratio = 1.42; 95% CI, 1.08-1.87) after controlling for the effect of preoperative diagnosis and lens status. Donor age and donor recipient ABO compatibility were not associated with rejection.

CONCLUSIONS

There was a substantially higher graft rejection rate in eyes with pseudophakic or aphakic corneal edema compared to that in eyes with Fuchs dystrophy. Female recipients were more likely to have a rejection event than male recipients. Graft rejection was not associated with donor age.

Clinical presentation, risk factors and treatment outcomes of first allograft rejection after penetrating keratoplasty in early and late postoperative period

PURPOSE

Corneal graft rejection is the most common reason for the failure of an allograft corneal transplant. We undertook this study to identify and compare risk factors and treatment outcomes for early and late corneal graft rejections after optical penetrating keratoplasty.

METHODS

A retrospective case file analysis of 880 primary penetrating keratoplasties was performed at a tertiary ophthalmic care centre. Patients were divided into early rejectors (rejection episode within 6 months postoperatively) and late rejectors (rejection episode after 6 months postoperatively). Main parameters evaluated were demographics, preoperative diagnosis and clinical signs, donor tissue details, surgical technique, details of rejection episode, treatment, and outcome information.

RESULTS

A total of 156 patients with rejection episodes were identified. Of these, 42 (26.9%) patients experienced early rejection episodes and 114 (73.1%) patients experienced late rejection episodes. Preoperative donor and recipient characteristics, surgical technique, and clinical presentation of graft rejection were found to be similar between both groups after a Bonferroni correction was applied (P>0.005). Treatment outcomes of graft rejections were not significantly different (P=0.46) between early and late rejectors, with 83% of patients responding to rejection treatment (80% early rejectors; 85% late rejectors).

CONCLUSION

Patients with early and late graft rejection have similar characteristics and both groups respond to treatment equally.

Baseline factors related to endothelial cell loss following penetrating keratoplasty

OBJECTIVE

To identify baseline (donor, recipient, and operative) factors that affect endothelial cell loss following penetrating keratoplasty for a moderate-risk condition (principally Fuchs dystrophy or pseudophakic or aphakic corneal edema).

METHODS

In a subset (n = 567) of Cornea Donor Study participants, preoperative and postoperative endothelial cell densities (ECDs) were determined by a central reading center. Multivariate regression analyses were performed to examine which baseline factors correlated with ECD over time.

RESULTS

Larger grafts (P < .001), younger donor age (P < .001), and female donor (P = .004) were significantly associated with higher ECD during follow-up. Median endothelial cell loss at 5 years was 68% for grafts larger than 8.0 to 9.0 mm in diameter, 75% for grafts 7.0 mm to smaller than 8.0 mm in diameter, and 74% for grafts 8.0 mm in diameter. Grafts from female donors experienced a 67% cell loss compared with a 72% cell loss among grafts from male donors. Method of tissue retrieval, donor cause of death, history of diabetes, and time from death to preservation or to surgery were not significantly associated with changes in ECD over time.

CONCLUSIONS

Following penetrating keratoplasty for endothelial dysfunction conditions, larger donor graft size, younger donor age, and female donor were associated with higher ECD over 5 years. These data warrant exploring the possibility that similar associations may exist following endothelial keratoplasty.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00006411.