Comparative Analysis of Corneal Parameters in Swept-Source Imaging between DMEK and UT-DSAEK Eyes

Ultrathin DSAEK versus DMEK - Review of systematic reviews

The efficacy and safety of Descemet's membrane endothelial keratoplasty (DMEK) and ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) have been recently compared in several systematic reviews (SRs). The aim of this study was to assess the evidence quality of such SRs, in order to obtain a scientifically rigorous comparison between the two techniques. We performed a systematic review of SRs and meta-analyses comparing the efficacy and safety between UT-DSAEK and DMEK up to 24th March 2023, using 3 electronic databases (PubMed, Cochrane Library, Google Scholar) plus manual reference search. Specific outcomes analyzed included best-corrected visual acuity (BCVA), endothelial cell density (ECD), rebubbling rate, and other postoperative complications. Of 90 titles/abstracts screened, four SRs met the inclusion criteria. All SRs adequately analyzed potential bias of the included studies. One SR raised concern for potential literature search bias and two SRs have heterogeneity in some outcomes analyzed. All SRs found higher BCVA after DMEK, but one SR reported significant heterogeneity. All SRs found significant heterogeneity in ECD analysis, with one SR providing inconsistent analysis of this outcome. Three SRs analyzed rebubbling rates, favoring UT-DSAEK over DMEK. Three SRs concluded a higher overall complication rate after DMEK, although rebubbling may be a confounding factor. This systematic review clarifies the strengths and weaknesses of published SRs and reinforces the conclusion that DMEK leads to superior visual outcomes compared to UT-DSAEK, with the trade-off of higher rebubbling rates and possibly other postoperative complications. Studies with longer follow-up are needed to ascertain these differences between procedures.

Scheimpflug Corneal Densitometry Patterns at the Graft-Host Interface in DMEK and DSAEK: A 12-Month Longitudinal Comparative Study

BACKGROUND

To compare corneal densitometry (CD) patterns at the graft-host interface between Descemet Membrane Endothelial Keratoplasty (DMEK) and Descemet Stripping Automated Endothelial Keratoplasty (DSAEK). Corneal densitometry is a quantitative assessment that objectively evaluates corneal clarity and optical quality by measuring the light backscatter from the cornea.

METHODS

Fifty-one eyes that received DMEK or DSAEK surgery for corneal endothelium dysfunction were evaluated. The primary endpoint included CD patterns at the graft-host interface, which were assessed by the Pentacam HR device at the center point of the corneal horizontal meridian (CDcentral), and at six points on the central circumference of the cornea (with a total diameter of 4 mm) (CDI,II,III,IV,V,VI). Secondary endpoints included the best-corrected distance visual acuity (BCDVA), central corneal thickness (CCT), and graft thickness (GT). All of the evaluations were performed at follow-up appointments one, three, six and twelve months after the procedure.

RESULTS

DMEK showed a significant overall CD reduction of -7.9 ± 8.5 grayscale unit (GSU) compared to DSAEK (p < 0.001). In addition, the DMEK group showed significantly lower CDCentral,I,II,III,IV,V,VI values at follow-up appointments one, three, six and twelve months after the procedure compared to the DSAEK group (p < 0.001). BCDVA, CCT and GT were in favor of the DMEK group with a mean value of 0.39 ± 0.35 LogMar, 552.2 ± 71.1 µm and 11.03 ± 1.4 µm, respectively (p < 0.001).

CONCLUSIONS

CD patterns at the graft-host interface seem to be different depending on the endothelial keratoplasty procedure. This provides specific insight into CD changes in this critical region of surgery, which may provide a better understanding of the postoperative evolution of these patients.

Descemet membrane endothelial keratoplasty compared with ultrathin Descemet stripping automated endothelial keratoplasty: a meta-analysis

AIMS

This study aims to compare the clinical outcome of Descemet membrane endothelial keratoplasty (DMEK) and ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) in patients with corneal endothelial dysfunction due to Fuchs' endothelial dystrophy or pseudophakic bullous keratopathy.

METHODS

We conducted a meta-analysis using a literature search of Embase, PubMed, Cochrane CENTRAL, ClinicalTrials.gov and WHO ICTRP databases. We included randomised controlled trials (RCTs) and cohort studies that compared DMEK and UT-DSAEK (graft<130 µm), with a follow-up of ≥12 months, published until 20 February 2022. We used the Revised Cochrane risk-of-bias tool for RCTs and the Risk of Bias in Non-Randomised Studies-of Interventions system for cohort studies.

RESULTS

Out of 144 records, 8 studies (3 RCTs, 2 fellow-eye studies and 3 cohort studies) were included, encompassing 376 eyes, (N=187 DMEK vs N=189 UT-DSAEK). The 12-month logarithm of the minimum angle of resolution best-corrected visual acuity (BCVA) was better post-DMEK (mean difference -0.06 (95% CI -0.10 to -0.02)), but with higher rebubbling risk: OR 2.76 (95% CI 1.46 to 5.22). Heterogeneity was significant I2=57%. Findings were consistent when excluding retrospective studies, including only studies with low risk of bias or RCTs only. An analysis of studies with mean DSAEK grafts <70 µm showed no significant difference in BCVA between the procedures. Publication bias was found in the BCVA analysis (Egger's test p=0.023).

CONCLUSIONS

Post-DMEK BCVA is superior to post-UT-DSAEK when using <130 µm grafts. DSAEK grafts <70 µm may not significantly differ from DMEK. The higher risk of rebubbling with DMEK necessitates an appropriate selection of patients.

PROSPERO REGISTRATION NUMBER

CRD42022340805.

Descemet Membrane Endothelial Keratoplasty (DMEK) Reduces the Corneal Epithelial Thickness in Fuchs' Patients

Fuchs' endothelial corneal dystrophy (FECD) is the occurrence of corneal edema due to endothelial cell dystrophy. Descemet membrane endothelial keratoplasty (DMEK) is considered to be the gold standard of treatment. The aim of this study was to investigate the changes in the corneal epithelial thickness of FECD patients before and after DMEK and to compare these results with a healthy control cohort. In this retrospective analysis, 38 eyes of patients with FECD that were treated with DMEK and 35 healthy control eyes received anterior segment optical coherence tomography (OCT; Optovue, XR-Avanti, Fremont, CA, USA). The corneal epithelial thicknesses in different locations were analyzed and compared between the preoperative, postoperative, and control cohorts. The median follow-up time was 9 months. There was a significant degression of the mean epithelial thickness after DMEK in the central, paracentral, and mid-peripheral zones (p < 0.01) of the cornea. The total corneal thickness and stromal thickness decreased significantly as well. No significant differences were observed between the postoperative and control cohorts. In conclusion, the FECD patients had an increased epithelial thickness compared to the healthy controls, which decreased significantly after DMEK and reached thickness levels comparable to those of healthy control eyes. This study emphasized the importance of distinguishing between the corneal layers in anterior segment pathologies and surgical procedures. Moreover, it accentuated the fact that the structural alterations in FECD extend beyond the corneal stroma.

Ultrathin-Descemet Stripping Automated Endothelial Keratoplasty Versus Descemet Membrane Endothelial Keratoplasty: A Systematic Review and Meta-analysis

BACKGROUND/AIM

The aim of this meta-analysis was to compare the efficacy and safety of Ultrathin - Descemet stripping automated endothelial keratoplasty (UT-DSAEK) versus Descemet membrane endothelial keratoplasty (DMEK) for the treatment of corneal endothelial failure in patients with Fuchs endothelial dystrophy (FED) or Pseudophakic bullous keratopathy (PBK).

PATIENTS AND METHODS

We performed a meta-analysis and conducted a literature search in PubMed and Cochrane Library, following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Effects were calculated as odds ratios or standardized mean differences.

RESULTS

A total of six studies with 300 eyes in total (151 UT-DSAE and 149 DMEK) were included. BSCVA was superior in the DMEK group compared with the UT-DSAEK at 3, 6, and 12 months after surgery. Rebubbling rates and overall adverse events were 2.37 and 1.48 times, respectively, higher in the DMEK group. The central corneal thickness and spherical equivalent were significantly lower in the DMEK group 12 months post-surgery. Endothelial cell density values were similar in both groups up to 12 months postoperatively.

CONCLUSION

To the best of our knowledge, this is the first meta-analysis comparing UT-DSAEK with DMEK. DMEK surgery resulted in significantly better BSCVA at 3, 6, and 12 months postoperatively compared to UT-DSAEK. UT-DSAEK had a better complication profile with lower rebubbling rates.

Systematic Review and Meta-analysis: Outcomes After Descemet Membrane Endothelial Keratoplasty Versus Ultrathin Descemet Stripping Automated Endothelial Keratoplasty

PURPOSE

To compare the efficacy and safety of ultrathin Descemet stripping (automated) endothelial keratoplasty (UT-DS(A)EK) versus Descemet membrane endothelial keratoplasty (DMEK) for the treatment of Fuchs endothelial dystrophy (FED) and bullous keratopathy (BK).

DESIGN

Systematic review and meta-analysis.

METHODS

Literature containing DMEK and UT-DSAEK were searched in the Cochrane Database of Systematic Reviews, PubMed, EMBASE, LILACS, and through manual reference searching. Studies were included that measured the outcome of interventions-including best corrected visual acuity (BCVA), endothelial cell density (ECD), and postoperative complications, especially graft detachment with the need of re-bubbling, graft rejection, graft failure, and postoperative elevated intraocular pressure (IOP)-in patients with FED and BK. Included outcomes were pooled as standardized mean differences (SMD) or risk ratios (RR) using random effects models. Inter-study heterogeneity was assessed using the Q-test and I2 statistic.

RESULTS

Seven (of 163) studies met all the inclusion and exclusion criteria. Meta-analysis showed a significantly better BCVA 12 months postoperatively, but an increased re-bubbling rate in eyes after DMEK compared with eyes after UT-DS(A)EK (BCVA: SMD = 0.50 [95% CI 0.27-0.74] and re-bubbling rate: RR = 0.33 [95% CI 0.16-0.67]). All other parameters did not differ significantly between both interventions, although estimates were imprecise (graft failure: RR = 0.65 [95% CI 0.18-2.30], graft rejection: RR = 1.40 [95% CI 0.27-7.30], and postoperative intraocular pressure elevation: RR = 1.14 [95% CI 0.60-2.18]). Postoperative SMDs of ECD could not be evaluated due to significant heterogeneity between studies.

CONCLUSIONS

Although the improvement in BCVA was higher after UT-DS(A)EK than after conventional DS(A)EK, the BCVA after DMEK was still superior. The complication rates were comparable for both procedures, except for the higher rate of re-bubbling after DMEK.