Primary Descemet’s Membrane Endothelial Keratoplasty for Fuchs Endothelial Dystrophy versus Bullous Keratopathy: Histopathology and Clinical Results

[Corneal changes in Fuchs endothelial corneal dystrophy and bullous keratopathy]

OBJECTIVE

Evaluation of structural and immunohistochemical features of cornea in Fuchs endothelial corneal dystrophy (FECD) and bullous keratopathy (BK).

MATERIAL AND METHODS

Group 1 - 44 patients (46 eyes) with FECD, group 2 - 42 patients (42 eyes) with BK. All patients underwent keratoplasty. Preoperative anterior segment optical coherence tomography (AS-OCT, RTVue-100, Optovue, USA) was performed. Endothelium-Descemet membrane (EDM) complexes, corneal buttons were obtained intraoperatively. Morphological (H&E staining) and immunohistochemical (primary antibodies to pancytokeratin, vimentin, fibronectin) studies were performed at the light microscope level (Leica DM-2500, Leica Application Suite V4.8, Leica Microsystems, Switzerland).

RESULTS

A direct correlation is found between the results of DM analysis in vivo with OCT and ex vivo with light microscopy. DM thickness (AS-OCT) was significantly greater in FECD (23.0 [19.0; 27.0] μm), than in BK (13.0 [12.0; 14.0] μm). Morphological study of EDM and corneal buttons showed similar difference in DM thickness: 17.9 [16.1; 20.0] μm in FECD and 11.9 [11.3; 13.0] μm in BK. Irregular optical density of stroma is a feature of edema and local fibrosis. In FECD and BK pancytokeratin is expressed in epithelial and endothelial cells, vimentin - in keratocytes, macrophages and vascular endothelium, fibronectin - in DM. In FECD, vimentin is expressed in endothelial cells.

CONCLUSION

FECD and BK are associated with different DM' and endothelium' abnormalities, which lead to similar changes of stroma and epithelium. AS-OCT is a useful method of FECD and BK in vivo diagnostics and the selection of treatment option.

Clinical Outcomes of Preloaded Descemet Membrane Endothelial Keratoplasty With Endothelium Inward: A 24-Month Comparative Analysis Between Fuchs Endothelial Corneal Dystrophy and Bullous Keratopathy

PURPOSE

The aim of this study was to compare long-term clinical outcomes of preloaded Descemet membrane endothelial keratoplasty (DMEK) between Fuchs endothelial corneal dystrophy (FECD) and bullous keratopathy (BK).

METHODS

In this single-center retrospective clinical case series, 71 eyes of 64 patients indicated with FECD (62%) or BK (38%) (with or without cataract) were treated with preloaded DMEK grafts between March 2018 and February 2020. Standard DMEK peeling, followed by manual folding of the tissue with endothelium-inward orientation and storing in a preloaded fashion inside a 2.2-mm intraocular lens cartridge. All tissues were delivered using a bimanual pull-through technique, followed by air tamponade. Graft unfolding time, endothelial cell loss, corrected distance visual acuity, central corneal thickness, rebubbling rate, and intraoperative and postoperative complications at 1, 3, 6, 12, and 24 months were recorded.

RESULTS

The mean intraoperative graft unfolding time in FECD did not differ from the BK group ( P = 0.6061). Cystoid macular edema did not differ in either group ( P = 0.6866). The rebubbling rate was found to be significantly higher in FECD compared with the BK group ( P = 0.0423). Corrected distance visual acuity significantly improved at the first month after surgery ( P = 0.0012), with no differences between FECD and BK at 24 months ( P = 0.2578). Central corneal thickness was stable postoperatively and showed no differences between the groups ( P = 0.3693). Significantly higher endothelial cell counts were observed in the FECD group at 24 months ( P = 0.0002).

CONCLUSIONS

Preloaded DMEK with "endothelium-in" offers acceptable intraoperative time, rebubbling rate, and clinical outcomes in both FECD and BK groups. Patients with FECD show better postoperative clinical outcomes even if the rebubbling rate is relatively high.

“Endothelium-Out” and “Endothelium-In” Descemet Membrane Endothelial Keratoplasty (DMEK) Graft Insertion Techniques: A Systematic Review With Meta-Analysis

Background

We evaluated the visual outcomes and complications of “endothelium-out” and “endothelium-in” Descemet membrane endothelial keratoplasty (DMEK) graft insertion techniques.

Materials and Methods

Electronic searches were conducted in CENTRAL, Cochrane databases, PubMed, EMBASE, ClinicalTrials.gov. Study designs included clinical trials, comparative observational studies, and large case series (≥25 eyes). PRISMA guidelines were used for abstracting data and synthesis. Random-effects models were employed for meta-analyses.

Results

21,323 eyes (95 studies) were included. Eighty-six studies reported on “endothelium-out” techniques; eight studies reported on “endothelium-in” techniques. One study compared “endothelium-out” to “endothelium-in” techniques. Eighteen “endothelium-out” studies reported that 42.5–85% of eyes achieved best-corrected visual acuity (BCVA) ≥20/25 at 6 months; pooled proportion of eyes achieving BCVA ≥20/25 at 6 months was 58.7% (95% CI 49.4–67.7%,15 studies). Three “endothelium-in” studies reported that 44.7–87.5% of eyes achieved BCVA of ≥20/25 at 6 months; pooled proportion of eyes achieving BCVA ≥20/25 at 6 months was 62.4% (95% CI 33.9–86.9%). Pooled mean endothelial cell loss was lower in the “endothelium-in” studies (28.1 ± 1.3%, 7 studies) compared to “endothelium-out” studies (36.3 ± 6.9%,10 studies) at 6 months (p = 0.018). Graft re-bubbling rates were higher in the “endothelium-out” studies (26.2%, 95% CI 21.9–30.9%, 74 studies) compared to “endothelium-in” studies (16.5%, 95% CI 8.5–26.4%, 6 studies), although statistical significance was not reached (p = 0.440). Primary graft failure rates were comparable between the two groups (p = 0.552). Quality of evidence was considered low and significant heterogeneity existed amongst the studies.

Conclusion

Reported rates of endothelial cell loss were lower in “endothelium-in” DMEK studies at 6 months compared to “endothelium-out” studies. Outcomes of “endothelium-in” techniques were otherwise comparable to those reported in “endothelium-out” studies. Given the technical challenges encountered in “endothelium-out” procedures, surgeons may consider “endothelium-in” techniques designed for easier intra-operative DMEK graft unfolding. “Endothelium-in” studies evaluating outcomes at longer time points are required before conclusive comparisons between the two techniques can be drawn.

[Morphological characteristics of Descemet's membrane removed during endothelial keratoplasty (case study)]

The two most used modifications of endothelial keratoplasty (EK) are Descemet's membrane endothelial keratoplasty (DMEK) and Descemet's stripping automated endothelial keratoplasty (DSAEK). The leading complication of EK surgeries is graft detachment in the early postoperative period. This article reports on two cases of endothelial graft adhesion depending on morphological characteristics of the Descemet's membrane (DM) removed during EK. In the first case, complete graft attachment to the recipient's posterior stroma was observed after DMEK. Morphological analysis of the DM showed clean stromal surface. In the second case there was a false chamber between the endothelial transplant and the posterior stroma of the patient. OCT scans revealed separate stromal fibers protruding into the false chamber; morphological analysis of the removed DM showed stromal fragments fixed to the anterior surface of the DM. The revealed changes indicate damage to the posterior stroma the suffered received during descemetorhexis, which may be the cause for incomplete graft attachment. Complete attachment after repeated EK (DSAEK) in this case was due to a thin stromal layer on the graft that provided high degree of adhesion to the posterior corneal surface. DSAEK can be indicated as a repeated EK surgery in cases of persistent endothelial graft non-attachment after DMEK.

Aqueous humour cytokine profiles after Descemet's membrane endothelial keratoplasty

The aim of this study was to compare aqueous humour (AqH) cytokine profiles before and after Descemet's membrane endothelial keratoplasty (DMEK) in eyes with bullous keratopathy (BK) and age-matched normal eyes. A total of 49 participants (mean age 75.0 ± 13.5 years) were divided into three groups: (1) BK patients scheduled for DMEK (BK group); (2) patients after DMEK (DMEK group; average postoperative time 1,018 ± 460 days); and (3) control participants without corneal endothelial disease scheduled for cataract surgery (control group). AqH (0.2 mL) was collected from all participants, and the levels of various AqH cytokines were simultaneously measured using a multiplex bead immunoassay. The DMEK group exhibited significantly lower concentrations of several pro-inflammatory cytokines, such as IL-1β, IL-5, IL-6, IL-10, and IL-8, and granulocyte colony stimulating factor than the BK group. In addition, the levels of IL-1β and IL-5 were significantly lower in the DMEK group than in the control group. The AqH levels of several pro-inflammatory cytokines were significantly reduced after DMEK, indicating that regeneration of the endothelial pump owing to the transplantation of a healthy endothelium might have a positive effect on anterior chamber inflammation.

Effect of Six-Month Postoperative Endothelial Cell Density on Graft Survival after Descemet Membrane Endothelial Keratoplasty

PURPOSE

To analyze if 6-month endothelial cell density (ECD) affects long-term ECD outcome and graft survival 5 years after Descemet membrane endothelial keratoplasty (DMEK) in eyes with Fuchs endothelial corneal dystrophy (FECD).

DESIGN

Retrospective cohort study.

PARTICIPANTS

A total of 585 DMEK eyes were included. The study group was divided into 4 groups based on 6-month ECD quartiles: group 1 (n = 146) with 313 to 1245 cells/mm², group 2 (n = 148) with 1246 to 1610 cells/mm², group 3 (n = 145) with 1611 to 1938 cells/mm², and group 4 (n = 146) with 1939 to 2760 cells/mm². Group 1 was further split into subgroups 1a (n = 36) with 6-month ECD of ≤828 cells/mm², 1b (n = 37) with 829 to 1023 cells/mm², 1c (n = 37) with 1024 to 1140 cells/mm², and 1d (n = 36) 1141 to 1245 cells/mm².

METHODS

Descemet membrane endothelial keratoplasty.

MAIN OUTCOME MEASURES

Long-term ECD, graft survival, and postoperative complication rates.

RESULTS

For group 1, 6-month ECD decreased from 951 (±233) cells/mm² (n = 146) to 735 (±216) cells/mm² (n = 99) at 5 years postoperatively. Group 1 graft survival probability was 0.95 (95% confidence interval [CI], 0.91-0.99] at 5 years postoperatively, which was lower than for groups 2 to 4 (P = 0.001). Five-year graft survival in subgroup 1a was 0.79 (95% CI, 0.67-0.94), which was lower than in subgroups 1b to 1d (P = 0.001). Preoperative ECD did not influence graft survival (P = 0.400), and higher 6-month ECD values were associated with lower graft failure rates (hazard ratio, 0.994; 95% CI, 0.99-1.00; P = 0.001).

CONCLUSIONS

Six-month ECD is associated with DMEK graft survival. High early cell loss after DMEK negatively affects long-term ECD outcome and graft survival. Grafts in the lowest 6-month ECD subgroup (≤828 cells/mm²) are at higher risk of failure within 5 years after DMEK. To ensure sufficiently high 6-month ECD, preoperative graft quality assessment should be optimized, and cellular stress induced to the graft should be minimized. Additionally, developing therapeutic options for the treatment of low postoperative ECD could further improve DMEK graft longevity.

Long-Term Outcome of Descemet Membrane Endothelial Keratoplasty in Eyes With Fuchs Endothelial Corneal Dystrophy Versus Pseudophakic Bullous Keratopathy

PURPOSE

The aim of this study was to compare the long-term outcome of Descemet membrane endothelial keratoplasty (DMEK) in patients with Fuchs endothelial corneal dystrophy (FECD) and pseudophakic bullous keratopathy (PBK).

METHODS

Records of consecutive DMEK surgeries performed between 2015 and 2016 at the Department of Ophthalmology, Cologne, Germany, were retrospectively reviewed from the prospective Cologne DMEK Database. Eyes with either PBK or FECD with a complete 3-year follow-up were enrolled. Main outcome parameters included central corneal thickness (CCT), peripheral corneal thickness (PCT), best spectacle-corrected visual acuity (BSCVA, logarithm of the Minimum Angle of Resolution), and endothelial cell count (ECC) before and after DMEK.

RESULTS

Four hundred two eyes from 402 patients were included (FECD n = 371, PBK n = 31). Preoperatively, CCT (FECD: 681.91 ± 146.78 μm; PBK: 932.25 ± 319.84 μm) and PCT (FECD: 732.26 ± 98.22 μm; PBK: 867.54 ± 88.72 μm) were significantly higher in the PBK group (P < 0.01). Three years after DMEK, CCT (FECD: 526.56 ± 27.94 μm; PBK 663.71 ± 132.36 μm) was significantly lower in both groups compared with the preoperative values (P < 0.01), whereas PCT showed no significant difference. PCT increased during the course in the PBK group from month 12 after DMEK (12 mo: 783.73 ± 127.73 μm; 24 mo: 837.50 ± 110.19 μm; 36 mo: 857.79 ± 140.76 μm). The increase in PCT correlated with an accelerated ECC loss starting 12 months after DMEK (P = 0.036). Before DMEK, BSCVA in FECD was significantly higher (P < 0.001) compared with that in PBK. After 3 years, BSCVA improved in FECD and PBK eyes without significant difference (P = 0.239).

CONCLUSIONS

Visual acuity after DMEK in PBK and FECD seems to be comparable during the long-term follow-up. Peripheral and central corneal edema seems to recur faster in eyes with PBK than in those with FECD. Therefore, using a donor graft with higher ECC or possibly a larger graft could be a promising approach for PBK patients.

Descemet Membrane Endothelial Keratoplasty Outcomes between Young and Old Graft Recipients

Purpose: To evaluated Descemet's membrane endothelial keratoplasty (DMEK) outcomes in young and old graft recipients.Materials and Methods: Data of 164 surgeries with a median age of 76 years (interquartile range 14 years) undergoing DMEK surgery between 2016 and 2018 was reviewed. Complications, graft survival, and visual acuity gain were compared between subjects in the 25th percentile (young recipients; aged 70 years and less, n = 21) and 75th percentile (old recipients; aged 85 years and over, n = 27) over the 2-year follow-up.Results: Young recipients had a lower rate of pre-operative glaucoma (14.3% vs. 51.9%, p = .014) and pseudophakic bullous keratopathy (9.5% vs. 59.3%, p < .001), and a higher rate of Fuchs endothelial dystrophy (57.1% vs. 14.8%, p = .002) and combined cataract extraction at the time of DMEK surgery (52.4% vs. 7.4%, p = .001) when compared to old recipients. Complications (primary graft failure, pupillary block, cystoid macular edema or infectious keratitis) were independent of graft recipient age. Descemet's membrane detachment requiring re-bubbling was observed more often in young compared to the old recipients (42.9% vs. 14.8%, p = .049). Visual acuity gain between the groups remained comparable up to 1-year, whereas at 2-years old recipients showed significantly declined visual acuity gains compared to the young recipients (0.14 ± 0.68 vs. 0.74 ± 0.49, p = .012). Graft recipients aged over 85 years had a considerably higher graft failure rate over the 24-months (40.7% vs. 4.8%, p = .006) and shorter graft survival time (p = .002; log-rank) when compared to the recipients aged under 70 years. After adjusting for potential confounders such as Fuchs endothelial dystrophy, pseudophakic bullous keratopathy and glaucoma, the recipients aged over 85 remained at higher risk for graft failure (HR = 17.278, 95% CI = 1.787-167.1, p = .014).Conclusions: In aged DMEK recipients, regardless of the low incidence of early postoperative complications, the rate of postoperative graft failure was significantly higher and graft survival shorter than in younger recipients.

Effect of Surgical Indication and Preoperative Lens Status on Descemet Membrane Endothelial Keratoplasty Outcomes

PURPOSE

To analyze 6-month results of 1000 consecutive Descemet membrane endothelial keratoplasty (DMEK) cases, and to evaluate if outcomes are influenced by surgical indication and preoperative lens status.

DESIGN

Retrospective, interventional case series.

METHODS

A series of 1000 eyes (738 patients) underwent DMEK mainly for Fuchs endothelial corneal dystrophy (FECD; 85.3%) or bullous keratopathy (BK; 10.5%). Main outcome measures were best-corrected visual acuity (BCVA), endothelial cell density, postoperative complications, and retransplantations.

RESULTS

At 6 months after DMEK, there was no difference in BCVA outcome between FECD and BK eyes (P = .170), or between phakic and pseudophakic FECD eyes (P = .066) after correcting for patient age and preoperative BCVA. Endothelial cell loss at 6 months postoperatively was similar for phakic and pseudophakic FECD eyes (39%; P = .852), but higher for BK eyes than for FECD eyes (46% vs 39%, P = .001). Primary and secondary graft failure occurred in 3 (0.3%) and 2 eyes (0.2%), respectively, and 7 eyes developed allograft rejection (0.7%). Eighty-two eyes (8.2%) received rebubbling for graft detachment and retransplantation was performed in 20 eyes (2.0%). Rebubbling was more often required in eyes treated for BK vs FECD eyes (12.4% vs 7.4%, P = .022).

CONCLUSION

DMEK consistently provides excellent short-term results, with similar high visual acuity levels for both FECD and BK eyes. As preoperative lens status did not influence DMEK outcomes, for phakic FECD eyes with a still relatively clear crystalline lens, lens preservation may be preferable in a selected group of younger patients, who may still benefit from their residual accommodative capacity.