Differential effects of primary disease and corneal vascularisation on corneal transplant rejection and survival

Comparison of repeat penetrating keratoplasty, DSAEK and DMEK for the management of endothelial failure of previous PK

PURPOSE

To compare the clinical outcomes of repeat PK, DSAEK-on-PK or DMEK-on-PK for the management of endothelial failure of previous penetrating keratoplasty.

DESIGN

Retrospective, interventional consecutive case series.

PARTICIPANTS

104 consecutive eyes of 100 patients requiring a second keratoplasty for endothelial failure of their primary penetrating keratoplasty performed between September 2016 and December 2020.

INTERVENTION

Repeat keratoplasty.

MAIN OUTCOME MEASURES

Survival and visual acuity at 12 and 24 months, rebubbling rate and complications.

RESULTS

Repeat PK was performed in 61/104 eyes (58.7%), DSAEK-on-PK was performed in 21/104 eyes (20.2%) and DMEK-on-PK was performed in 22/104 eyes (21.2%). Failure rates in the first 12 and 24 months were 6.6% and 20.6% for repeat PKs compared to 19% and 30.6% for DSAEK and 36.4% and 41.3% for DMEK. For those grafts surviving 12 months, the chances of surviving to 24 months were greatest for DMEK-on-PK at 92% vs 85% each for redo PK and DSAEK-on-PK. Visual acuity at one year was logMAR 0.53 ± 0.51 in the redo PK group, 0.25 ± 0.17 for DSAEK-on-PK and 0.30 ± 0.38 for DMEK-on-PK. 24-month outcomes were 0.34 ± 0.28, 0.08 ± 0.16, and 0.36 ± 0.36 respectively.

CONCLUSIONS

DMEK-on-PK has a greater failure rate in the first 12 months than DSAEK-on-PK which has a greater failure rate than redo PK. However, the 2-year survival rates in our series for those already surviving 12 months were greatest for DMEK-on-PK. There was no significant difference in visual acuity at 12 or 24 months. Careful patient selection is needed by experienced surgeons to determine which procedure to offer to patients.

Graphical comparison of surgeon outcomes for the audit of a national corneal transplant registry (OTAG study 32)

PURPOSE

To compare Kaplan-Meier survival curves and funnel plots for the audit of surgeon-specific corneal transplantation outcomes.

METHODS

We obtained data on all patients with Fuchs endothelial dystrophy (FED) receiving a first corneal transplant in one eye between January 2012 and December 2017. We produced 2-year Kaplan-Meier graft survival curves to compare a simulated individual surgeon's graft survival rate to national pooled data. We used funnel plots to compare all surgeon outcomes to the national graft survival rate with superimposed 95 and 99.8% confidence limits. We defined an outlier as a surgeon who performed ≥10 transplants and had graft survival below the 99.8% national lower limit. To assess the effect of the surgeon case mix, we also compared unadjusted and risk-adjusted graft survival rates.

RESULTS

There were 3616 first corneal transplants for FED patients with complete data, performed or overseen by 196 surgeons. The 2-year national graft survival rate was 88%. The median change from the unadjusted to the risk-adjusted graft survival rate for individual surgeons was 0% (IQR: 0%- -2%). Of the 108 surgeons who had performed ≥10 transplants, we identified two outliers based on the unadjusted graft survival funnel plot, compared to four outliers based on the risk-adjusted graft survival funnel plot.

CONCLUSION

Funnel plots provide a visually accessible method for comparing individual graft survival rates to the national rate. Risk-adjustment accounts for clinical factors, and this has advantages for audit and clinical governance.

Big data in corneal diseases and cataract: Current applications and future directions

The accelerated growth in electronic health records (EHR), Internet-of-Things, mHealth, telemedicine, and artificial intelligence (AI) in the recent years have significantly fuelled the interest and development in big data research. Big data refer to complex datasets that are characterized by the attributes of "5 Vs"-variety, volume, velocity, veracity, and value. Big data analytics research has so far benefitted many fields of medicine, including ophthalmology. The availability of these big data not only allow for comprehensive and timely examinations of the epidemiology, trends, characteristics, outcomes, and prognostic factors of many diseases, but also enable the development of highly accurate AI algorithms in diagnosing a wide range of medical diseases as well as discovering new patterns or associations of diseases that are previously unknown to clinicians and researchers. Within the field of ophthalmology, there is a rapidly expanding pool of large clinical registries, epidemiological studies, omics studies, and biobanks through which big data can be accessed. National corneal transplant registries, genome-wide association studies, national cataract databases, and large ophthalmology-related EHR-based registries (e.g., AAO IRIS Registry) are some of the key resources. In this review, we aim to provide a succinct overview of the availability and clinical applicability of big data in ophthalmology, particularly from the perspective of corneal diseases and cataract, the synergistic potential of big data, AI technologies, internet of things, mHealth, and wearable smart devices, and the potential barriers for realizing the clinical and research potential of big data in this field.

Keratoplasty Registries: Lessons Learned

ABSTRACT

Clinical registries have been developed for decades in the field of ophthalmology, and they are especially well-suited to the study of keratoplasty practices. A comprehensive donor/recipient registry system can provide insight into donor, recipient, and surgical factors associated with immediate and long-term outcomes and adverse reactions. Furthermore, linkage with demographic databases can elucidate relationships with social determinants of health and potentially shape public policy. The vast sample size and multicenter nature of registries enable researchers to conduct sophisticated multivariate or multilayered analyses. In this review, we aim to emphasize the importance of registry data for keratoplasty practice and 1) summarize the structure of current keratoplasty registries; 2) examine the features and scientific contributions of the registries from Australia, the United Kingdom, Singapore, the Netherlands, Sweden, Eye Bank Association of America, and European Cornea and Cell Transplant registries; 3) compare registry-based studies with large single-site clinical studies; 4) compare registry-based studies with randomized control studies; and 5) make recommendations for future development of keratoplasty registries. Keratoplasty registries have increased our knowledge of corneal transplant practices and their outcomes. Future keratoplasty registry-based studies may be further strengthened by record linkage, data sharing, and international collaboration.

Review of Corneal Graft Registries

PURPOSE

Corneal graft registries are organized systems that collect and analyze outcome data (such as long-term graft survival and visual outcomes) after keratoplasty procedures. The aim of this review was to identify existing corneal graft registries and to describe their characteristics.

METHODS

A search of the PubMed database was performed on June 1, 2021, for articles pertaining to corneal graft registries.

RESULTS

The PubMed literature search yielded 958 publications, of which 116 met all the inclusion and exclusion criteria. Among these articles, 15 corneal graft registries were identified, including 6 regional registries, 8 national registries, and 1 multinational registry. This article provides an overview of their characteristics and discusses the main advantages and pitfalls of clinical registries.

CONCLUSIONS

Clinical registry data are increasingly recognized as a valuable tool to monitor corneal transplant outcomes to improve health care services and optimize resource management.

Survival Outcome and Prognostic Factors of Corneal Transplantation: A 15-Year Retrospective Cohort Study at King Chulalongkorn Memorial Hospital

Purpose

To evaluate long-term survival outcomes and determine the prognostic factors of corneal transplantation performed at a tertiary referral hospital in Thailand.

Design

A 15-year retrospective cohort study.

Materials and Methods

One corneal graft per patient was selected; graft failure was defined as graft opacity due to recurrent disease or endothelial cell dysfunction. Kaplan–Meier survival analysis was performed. Median time to failure was compared using the Log rank test. Prognostic factors were identified using the Cox proportional hazards model.

Results

We enrolled 704 transplanted grafts. Surgical indications were optical (88.5%), therapeutic (10.2%), and tectonic (1.3%). The most common diagnoses were corneal opacity (25.3%), bullous keratopathy (15.8%), and regraft (14.8%). The overall survival rates at 1, 3, 5, and 10 years were 87.5%, 72.0%, 59.2%, and 41.7%, respectively. Univariate analysis identified age, primary diagnosis, graft size, pre-existing glaucoma, prior lens status, prior intraocular surgery, indication for surgery, donor endothelial cell density, and previous graft rejection as prognostic factors for graft failure. Multivariate analysis revealed three prognostic factors: primary diagnosis of perforation/peripheral ulceration/Mooren’s ulcer (hazard ratio [HR]=28.57; 95% confidence interval [CI], 6.32–129.16; P<0.001), active keratitis (HR=24.30; 95% CI, 5.88–100.43; P<0.001), regraft (HR=9.37; 95% CI, 2.27–38.66; P=0.002), and pseudophakic/aphakic bullous keratopathy (HR=7.97; 95% CI, 1.93–32.87; P=0.004); pre-existing glaucoma (HR=1.52; 95% CI, 1.13–2.04; P=0.006); and previous graft rejection (HR=1.95; 95% CI, 1.54–2.48; P<0.001).

Conclusion

Overall corneal graft survival rate was high in the first postoperative year and decreased after that. Primary diagnosis, pre-existing glaucoma, and previous graft rejection negatively influenced graft survival.

Recent Advances in Natural Materials for Corneal Tissue Engineering

Given the incidence of corneal dysfunctions and diseases worldwide and the limited availability of healthy, human donors, investigators are working to generate engineered cellular and acellular therapeutic approaches as alternatives to corneal transplants from human cadavers. These engineered strategies aim to address existing complications with human corneal transplants, including graft rejection, infection, and complications resulting from surgical methodologies. The main goals of these research endeavors are to (1) determine ideal mechanical properties, (2) devise methodologies to improve the efficacy of engineered corneal grafts and cell-based therapies, and (3) optimize transplantation of engineered tissue structures in the eye. Thus, recent innovations have sought to address these challenges through both in vitro and in vivo studies. This review covers recent work aimed at evaluating engineered materials, potential therapeutic cells, and the resulting cell-material interactions that lead to optimal corneal graft properties. Furthermore, we discuss promising strategies in corneal tissue engineering techniques and in vivo studies in animal models.

Survey of Rejection Prophylaxis Following Suture Removal in Penetrating Keratoplasty in Germany

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.

Keratoplasty Outcomes in Patients With Uveitis

PURPOSE

To examine the corneal transplant failure rates and associations with uveitic eye disease.

METHODS

The retrospective chart review identified 70 eyes from 42 patients with uveitis that underwent 40 primary transplants and 30 repeat transplants at 2 major academic centers over a 9-year period. The graft failure rate was calculated. Variables hypothesized to be associated with graft failure were analyzed as covariates using a Cox proportional hazards analysis clustered by the patients to determine their association with failure rates.

RESULTS

Of the 70 grafts, the mean duration of follow-up for patients was 40.6 months (range 4-90 months) and the median survival time was 24.1 months (interquartile range of 9-290 months). Twenty-two patients (52%) had graft failure. There was a higher rate of graft failure in patients with infectious uveitis as compared to those with noninfectious uveitis (hazard ratio 2.46, P = 0.031). Patients with successful grafts had their inflammation controlled for a longer period of time before transplantation as compared to those with failed grafts (38.6 vs. 13.6 months, P = 0.004). Worse preoperative visual acuities were significantly associated with graft failure (P < 0.001).

CONCLUSIONS

There is limited knowledge of corneal transplant outcomes in uveitic patients in the current literature. In our study, over half of the grafts failed. Infectious uveitis (especially viral) was a strong predictor of graft failure. A shorter period of inflammation control before transplantation, previously failed grafts, and worse preoperative visual acuity were also associated with graft failure.

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.