Descemet's Membrane Endothelial Keratoplasty. Indication, technique chirurgicale, gestion postopératoire et revue de la littérature

Is ultra-thin Descemet stripping automated endothelial keratoplasty a viable alternative to Descemet membrane endothelial keratoplasty? A systematic review and meta-analysis

Background

Ultra-thin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) is a recently developed surgical procedure that has shown promising results for the management of various corneal endothelial diseases.

Objectives

To evaluate the outcomes of the UT-DSAEK to the Descemet membrane endothelial keratoplasty (DMEK).

Design

A systematic analysis of the studies comparing UT-DSAEK with DMEK by evaluating one or more outcomes (vision, complications, and post-operative endothelial cell counts) was performed. The meta-analysis was done if two or more studies reported a common outcome.

Methods

We used PubMed, EMBASE, and SCOPUS databases to identify articles comparing the outcomes of UT-DSAEK with DMEK and performed a meta-analysis using RevMan, version 5.4.

Results

A total of six studies were included in this review (two randomized clinical trials and four non-randomized comparative studies). Our analysis showed the patients who underwent DMEK cases showed better visual outcomes with a mean difference of 0.06 LogMAR (95% CI: 0.04-0.09) in BCVA, albeit with i ² of 52% (heterogenous values). The evidence was weak, with the most weightage on retrospective studies. UT-DSAEK showed significantly fewer complications such as graft dislocations, with an odds ratio of 0.25 (95% CI: 0.13-0.48). There was no significant difference in the endothelial cell counts with a mean difference of 86.34 (95%CI: -133.09 to -305.77).

Conclusion

Although the literature is limited on UT-DSAEK with post-operative visual acuity that could be practically at par with DMEK, lesser complication rates and comparable post-operative endothelial cells could be a suitable alternative to DMEK for corneal endothelial pathologies.

DMEK graft: One size does not fit all

Descemet membrane endothelial keratoplasty (DMEK) is a popular procedure for the treatment of corneal endothelial diseases mainly targeting Fuchs endothelial corneal dystrophy (FECD) and pseudophakic bullous keratopathy (PBK). Although DMEK has multiple advantages, it is challenging in terms of graft preparation and delivery. One of the crucial factors of DMEK graft preparation is determining the size of the graft. Evaluating risks and benefits of transplanting larger or smaller grafts compared with the descemetorhexis performed following a standard DMEK procedure thus becomes important. Advanced techniques like pre-loaded DMEK requires pre-selection of graft diameter without physical examination of the eye making it more challenging. Therefore, recognizing the benefits of graft size and the number of transplanted endothelial cells becomes essential. Smaller DMEK grafts have been preferred and accepted for grafting. Larger diameter grafts have advantages but can be challenging due to higher detachment rates. We thus aim to review the challenges of preparing and delivering DMEK tissues with small or large diameter based on selected descemetorhexis area, discuss the outcomes based on different graft sizes, highlight related complications and suggest which cases may benefit from adopting smaller or larger graft size.

DMEK Without Postoperative Supine Posturing

PURPOSE

The purpose of this study was to describe the incidence of graft detachment after Descemet membrane endothelial keratoplasty (DMEK) without postoperative supine posturing.

METHODS

A total of 106 eyes of 84 patients with Fuchs endothelial corneal dystrophy or bullous keratopathy (BK) were operated by a single experienced surgeon with DMEK with a 99% anterior chamber air bubble fill, recovered in an upright (seated) position, and then discharged without instructions to remain supine. Postoperatively, all eyes were evaluated for graft detachment through anterior segment optical coherence tomography at predetermined intervals (1 d, 1 wk, and 1 mo). Detachments were regarded as clinically significant if they subtended 30% of the total graft surface area or involved the visual axis.

RESULTS

Clinically significant graft detachments were observed in 23 of 106 eyes (22%) in the no-supine posturing cohort, including 22 of 85 eyes (26%) operated for Fuchs endothelial corneal dystrophy and 1 of 21 eyes (5%) operated for BK. Compared with a historical comparison group of eyes undergoing DMEK with 48 hours of postoperative supine posturing, the risk of graft detachment was not increased. In both cohorts, 6% of operated eyes required regrafting for either persistent detachment or primary graft failure. No additional intraoperative or postoperative complications were experienced.

CONCLUSIONS

Particularly in eyes operated for BK, the supine posturing requirement after DMEK may be eliminated without increasing the absolute risk for clinically significant graft detachment.

[UT-DSAEK using grafts provided by a tissue bank, a one-year follow-up study of 79 grafts]

INTRODUCTION

UT-DSAEK is a recent technique developed in order to obtain grafts thinner than a conventional DSAEK (less than 100 microns). The goal of this study was to evaluate the anatomic and clinical results over a period of one year for a retrospective series of UT-DSAEK procedures at the University Hospital of Nantes, using pre-cut grafts provided by a tissue bank, and to compare results with other existing techniques: DSAEK and DMEK.

METHODS

In this retrospective, single-center study, all patients requiring an endothelial graft over a one-year period were included. The criteria studied were visual acuity, graft thickness, pachymetry and specular microscopy, recorded on the preoperative visit, D7, M1, M3, M6 and M12.

RESULTS

Seventy-nine grafts were performed on 75 patients. The mean age was 72 years. Between the 7th day and the end of the first year, the graft thickness in the visual axis decreased from 75±29 to 60±21 microns rapidly over the first three months. The pachymetry decreased from 706±95 microns preoperatively to 561±54 microns with the same kinetics. The cell density of the graft decreased from 2604±13 cell/mm² prior to the procedure to 1551±124 cell/mm² (40% loss) at one year. The preoperative visual acuity was 1.16 logMAR, rapidly improving to 0.65 logMAR at the first month and 0.40 logMAR at one year.

CONCLUSION

This study provides a fair amount of data on the progression of UT-DSAEK grafts: a decrease in graft thickness over the first three months, corresponding to an increase in visual acuity over this same period, with a good endothelial survival rate. This technique opens new avenues for the treatment of endothelial diseases, being complementary to DMEK in terms of surgical indications.

Descemet membrane endothelial keratoplasty (DMEK): an update on safety, efficacy and patient selection

Descemet membrane endothelial keratoplasty (DMEK) is gaining popularity worldwide as a procedure to address corneal endothelial dysfunctions. Its perfect anatomical result improves outcomes and expedites visual recovery. This review addresses important aspects of safety, efficacy and patient selection.

Update on Descemet membrane endothelial keratoplasty

PURPOSE OF REVIEW

To provide an update on new perspectives on Descemet membrane endothelial keratoplasty (DMEK).

RECENT FINDINGS

Preloaded DMEK grafts allow optimization of DMEK surgery time and reduce costs of the procedure, which is allowing the procedure to become more easily performed as reflected in the increasing number of cases. The surgical technique in the United States differs from the technique in Europe, but outcomes have been similar. Hemi-DMEK and quarter-DMEK have shown similar outcomes to conventional DMEK with respect to corneal transparency and visual acuity. Three-year follow-up of hemi-DMEK has also shown stability in endothelial cell count while maintaining corneal transparency.

SUMMARY

DMEK is becoming more accepted as the procedure of choice for treating endothelial failure. However, challenges with the surgical technique have limited wider implementation of this lamellar corneal transplantation. Preloaded DMEK provides one solution for the surgical challenges associated with the procedure while also reducing costs. Variations in the surgical technique for DMEK, including hemi-DMEK and quarter-DMEK, allow for central corneal clarity similar to traditional DMEK, but both result in lower endothelial cell density (ECD).

[Comparative analysis of modern methods of preparing donor material for endothelial keratoplasty]

PURPOSE

To evaluate various methods of stripping Descemet's membrane of a donor corneoscleral flap for Descemet's membrane endothelial keratoplasty (DMEK).

MATERIAL AND METHODS

The study included 60 corneoscleral flaps (mean donor age was 62.9 years) from the eye bank of Research Institute of Eye Diseases, which were not suitable for clinical use due to positive serological results. Four alternative methods of donor material dissection in preparation for DMEK were compared: SCUBA (group A), our newly suggested method utilizing intracapsular ring (group B), 'liquid bubble' (group C), 'big bubble' (group D). Parameters under evaluation were mean transplant preparation time, density of endothelial cells before and after dissection, presence of complications during detachment of Descemet's membrane.

RESULTS

Mean detachment time in group A was 8.5 min, in group B - 7 min, in group C - 8 min, and in group D - 5 min. Loss of endothelial cells as compared with baseline was in average 10.5% in group A, 9.3% in group B, 10.7% in group C, and 10.3% in group D. Group A had two cases with complications occurring during separation of Descemet's membrane, group B had one such case, group C - 2 cases, and group D - 3 cases. Histologic examination confirmed absence of stromal fibers on the detached Descemet's membrane in groups A, B and C.

CONCLUSION

Among the described methods of preparing donor material for DMEK surgery, all except 'big bubble' proved equal in terms of resulting transplant quality. The 'big bubble' dissection technique requires more time to complete, while the resulting transplant has stromal fibers. Our newly suggested method of Descemet's membrane stripping that utilizes intracapsular ring proved safe and effective alternative for preparing donor material for DMEK.