Is there evidence for a surgeon learning curve for endothelial keratoplasty in Australia?

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.

Trends in Early Graft Failure Leading to Regrafting After Endothelial Keratoplasty in the United States

PURPOSE

The purpose of this study was to report trends in the prevalence of early graft failure after endothelial keratoplasty in the United States.

METHODS

Descemet membrane endothelial keratoplasty (DMEK) and Descemet stripping automated endothelial keratoplasty (DSAEK) graft volumes were collected from records maintained by 6 major eye banks in the United States from January 1, 2013, to December 31, 2018. The prevalence and presumed cause of early graft failures (defined as a graft with persistent edema or regrafted within 8 weeks after keratoplasty) each year were sourced from surgeon-reported adverse events. Failed graft cases from the 3 eye banks were compared with nonfailures at the donor and recipient levels to perform subset analysis of factors associated with early graft failure.

RESULTS

A total of 51,887 endothelial keratoplasty tissues were distributed during the study period; 72% were DSAEK grafts. The total number of early graft failures reported was 168 of 14,284 (1.18%) for DMEK and 322 of 37,603 (0.86%) for DSAEK. Early DMEK failures decreased from 2013 (7.69%) to 2018 (0.68%). In generalized linear mixed model analyses adjusting for donor tissue characteristics, recipient age, and diagnosis, an association of borderline significance was found between higher donor age and early failure [odds ratio (95% confidence interval): 1.03 (1.00-1.05); unit change of 1 yr] and DSAEK [odds ratio 1.02 (1.00-1.04); unit of change 1 yr] cases.

CONCLUSIONS

The proportion of early graft failures in DMEK decreased over time and was comparable with failure rates in DSAEK at the end of the study period. The surgical learning curve might have played a role.

Determining the learning curve for a novel microsurgical procedure using histopathology

PURPOSE

Wet laboratories are becoming an increasingly important training tool as part of a push to a proficiency-based training model. We created a microsurgical wet laboratory to investigate the utility of histopathology use in assessing surgical outcomes and determine the learning curve of a novel microsurgical procedure.

METHODS

A microsurgical wet laboratory was established using pig eyes to simulate the human cornea. Three novice surgeons and an experienced surgeon performed an anterior cornea lamellar dissection and the duration of the procedure was recorded. With the aid of histological analysis, the thickness and characteristics of the dissected graft was recorded. The number of attempts to complete the experiment, defined as three successful dissections with mean thickness below 100 μm, was documented.

RESULTS

The use of histopathology was highly successful allowing in-depth analysis of the dissected graft for each attempt. Trainees reached the endpoint of the study in 21, 26 and 36 attempts (mean: 28 attempts) whilst the corneal surgeon completed the experiment in 12 attempts (p = 0.07). Mean dissection thickness decreased over time for all participants. The mean dissection time for trainees was 10.6 ± 4.2 min compared to the corneal surgeon with a mean of 8.2 ± 3.1 min (p = 0.03).

CONCLUSION

We propose a corneal wet laboratory model that allows for simple, efficient, and flexible microsurgical training. The use of histopathological analysis allows for careful graft analysis, providing objective feedback throughout the training exercise. Trainees demonstrated improvements in the three key aspects of the procedure: accuracy as evidenced by decreasing histological thickness, confidence by self-report and fluidity by decreasing duration of the procedure.

A 5-year analysis of endothelial vs penetrating keratoplasty graft survival in Chinese patients

AIM

To determine if there is any difference in long term graft survival between Descemet's stripping endothelial keratoplasty (DSEK) and penetrating keratoplasty (PK).

METHODS

A retrospective 5-year cases analysis of bullous keratopathy secondary to Fuchs' endothelial dystrophy or pseudophakic bullous keratopathy, receiving either DSEK or PK. A total of 42 DSEK cases and 25 PK cases were included in the analysis.

RESULTS

In the 5-year analysis, graft survival rates were very similar in the two groups (DSEK 77.1% vs PK 76.0%, P=0.918, 95%CI: -6.3 to 33.4). Sub-analyses at 1y (DSEK 81% vs PK 95%, P=0.085, 95%CI: -29 to 3.6) and 2y (DSEK 81% vs PK 88%, P=0.381, 95%CI: -25.9 to 11.8) show a trend towards lower survival rates of DSEK vs PK, but the results were not statistically significant.

CONCLUSION

Long term 5-year graft survival is similar between the DSEK and PK methods of corneal transplant in Chinese patients with bullous keratopathy.

Clinical Outcomes of Penetrating Keratoplasty and Descemet Stripping Automated Endothelial Keratoplasty in Asian Population with American Corneas

To determine the comparative efficacy and safety of penetrating keratoplasty (PK) and Descemet stripping automated endothelial keratoplasty (DSAEK) in the Asian population receiving imported donor corneas, our single-center retrospective study provides analysis supporting the transition from PK to DSAEK in the Asian population using imported American donor corneas. We analyzed 259 patients with 241 and 57 cases of PK and DSAEK respectively during 2008 to 2017 using imported corneas at Chang Gung Memorial Hospital, Linkou, Taiwan. In terms of long-term graft survival analysis, there was no difference between PK and DSAEK (log-rank p = 0.386, HR = 0.920, 95% CI: [0.641–1.380]). However, Cox proportional regression analysis revealed that corneal survival rate of DSAEK group in the first 100 days after transplantation was inferior than that of PK group (log-rank p < 0.001, HR = 2.733, 95% CI: [1.501–4.977])]. Despite the inferior survival rate, there were significantly less neovascularization and Descemet membrane folds in the DSAEK group. Importantly, the non-complication rate of DSAEK was much higher than that of PK with significant difference (PK, 25.7% vs. DSAEK 42.0%, p = 0.022). Collectively, DSAEK is suggested as an alternative surgical modality in Asian patients using imported American donor corneas because of less complication, and no difference in long-term corneal graft survival rates between PK and DSAEK.

The Rapid Transformation of Transplantation for Corneal Endothelial Diseases: An Evolution From Penetrating to Lamellar to Cellular Transplants

The cornea is the major focusing structure of the human eye and the corneal endothelium maintains the relatively dehydrated state of the cornea required for clarity. The endothelial cells respond to disease or injury by migration and cellular enlargement. Our current understanding is that there is a very limited degree of proliferative or regenerative capacity in the human corneal endothelium. Thus, corneal endothelial diseases may result in corneal edema, significantly impact vision and quality of life. Contemporary surgical transplantation options for treating moderate to advanced endothelial dysfunction include penetrating keratoplasty (PK), Descemet stripping endothelial keratoplasty (DSEK), and Descemet membrane endothelial keratoplasty. Advances in surgical techniques aim to bring faster visual recovery and improve visual outcomes; however, there is still a significant donor cornea shortage worldwide and alternative methods for treatment for corneal endothelial disease are rapidly evolving. Indeed, we are at a pivotal point in corneal transplantation for endothelial disease and novel surgical strategies include using 1 donor for multiple recipients, a minimally attached endothelial graft, and Descemet membrane stripping only. Crucially, forthcoming approaches include the use of Rho-Kinase (ROCK) inhibitors, endothelial cell therapy, tissue engineered grafts, and consideration of stem cell techniques. Ultimately, the choice of technique will be dependent on recipient factors such as age, type of endothelial disease, extent of the disease, and associated ocular disorders. The safety and efficacy of these rapidly developing treatments warrant further investigations. In time, some or all of these alternatives for corneal transplantation will alleviate the reliance on limited corneal donor tissue.

Prospective evaluation of clinical outcomes between pre-cut corneal grafts prepared using a manual or automated technique: with one-year follow-up

Purpose

Posterior lamellar corneal surgery is considered the standard of care for irreversible endothelial cell dysfunction. Pre‐cut grafts can be prepared either manually (Descemet stripping endothelial keratoplasty; DSEK) or mechanically (Descemet stripping automated endothelial keratoplasty; DSAEK). We performed a head‐to‐head clinical comparison between DSEK and DSAEK grafts.

Methods

All DSEK and DSAEK procedures performed by two corneal specialists at the University Medical Center Utrecht from 1 January 2016 through 31 October 2016 were prospectively included. Pre‐cut grafts were delivered by two eye banks, which either exclusively prepared the DSEK or DSAEK grafts. Preoperative and postoperative measurements were obtained, and all surgical events and adverse events were recorded.

Results

A total of 21 DSEK and 53 DSAEK procedures were included for analysis; the two groups were similar at baseline, with the exception of graft endothelial cell density, which was 2531 ± 67 versus 2748 ± 148 cells/mm², respectively (p < 0.001). At the one‐year follow‐up visit, corrected distance visual acuity and endothelial cell loss were similar between the groups. Mean pachymetry was significantly lower in the DSEK group (521 ± 39 versus 588 ± 59 μm; p < 0.001), whereas the rebubbling rate was significantly higher in the DSEK group (47.6% versus 18.9%; p = 0.001). Finally, three grafts in the DSEK group experienced failure compared to one graft in the DSAEK group (14% versus 1.9%, respectively).

Conclusion

Manually dissected and microkeratome‐dissected grafts performed similarly with respect to vision and endothelial cell loss assessed one year after surgery. The higher incidence of graft failure among manually dissected (i.e. DSEK) grafts may be attributable to reduced relative thickness compared to DSAEK grafts and/or the resulting differences in tissue handling and the surgeon's learning curve.

Long-term Outcomes of Repeated Corneal Transplantations: A Prospective Dutch Registry Study

PURPOSE

To compare long-term outcomes of repeated corneal transplantations (CT), based on primary indication (Fuchs endothelial dystrophy [FED] vs pseudophakic bullous keratoplasty [PBK]), surgical technique (penetrating keratoplasty [PK] vs endothelial keratoplasty [EK]), and indication for repeated grafting.

METHODS

In this nonrandomized treatment comparison with national registry data (Netherlands Organ Transplantation Registry, NOTR), data on all consecutive repeated CT following primary PK or EK for FED and PBK between 1994 and 2015 were analyzed, with a maximal follow-up of 5 years. Regraft survival was analyzed using Kaplan-Meier survival curves and univariable and multivariable Cox regression analysis. Secondary outcomes best-corrected visual acuity, spherical equivalent, and refractive astigmatism were compared using linear mixed-model analysis.

RESULTS

A total of 332 repeated CT were analyzed. The number of regrafts increased significantly between 2007 and 2015 (P = .001). Overall 5-year regraft survival was 60% and was higher for FED vs PBK (77% vs 45%, HR = 0.40, P = .001), and re-EK vs re-PK (81% vs 55%, HR = 0.51, P = .041). However, multivariable analysis showed no significant difference in survival based on primary indication, surgical technique, and indication for regrafting. Corrected for baseline, secondary outcomes also did not differ between groups.

CONCLUSIONS

We found a significant increase in repeated CT, coinciding with the introduction of EK in the Netherlands. While univariable analysis suggested better overall regraft survival for FED and (re-)EK, multivariable analysis showed no such difference. This may be owing to allocation of favorable cases to undergo (re-)EK. Similarly, secondary outcomes were determined by the primary CT technique.