Descemet Membrane Endothelial Keratoplasty as Treatment for Graft Failure After Descemet Stripping Automated Endothelial Keratoplasty ¨ TZER-SCHREHARDT, JULIA M. WELLER, THEOFILOS TOURTAS, FRIEDRICH E. KRUSE, URSULA SCHLO ¨ RN O. BACHMANN THOMAS FUCHSLUGER, AND BJO
PURPOSE:
To investigate the outcome of Descemet membrane endothelial keratoplasty (DMEK) in patients with graft failure after Descemet stripping automated endothelial keratoplasty (DSAEK). DESIGN: Retrospective cohort study. METHODS: SETTING: Institutional. STUDY POPULATION: Fifteen eyes of 15 patients that underwent DMEK for graft failure with corneal decompensation following DSAEK were analyzed; 15 eyes with primary DMEK for Fuchs corneal dystrophy were included as control group. MAIN OUTCOME MEASURES: Best-corrected visual acuity (BCVA), endothelial cell density (ECD), central corneal thickness (CCT), and rebubbling rate. RESULTS: DMEK surgery was successful in all cases of both groups. Mean BCVA (logMAR) before DMEK was 1.27 ± 0.34 in the DMEK after DSAEK group and 1.0 ± 0.40 in the Primary DMEK group. After DMEK, mean BCVA increased significantly to 0.23 ± 0.21 (P [ .012, DMEK after DSAEK group) and 0.29 ± 0.23 (P [ .042, Primary DMEK group) after 3 months. There were no significant differences in mean BCVA between both groups at each visit. The rebubbling rate was 13% in the DMEK after DSAEK group and 40% in the Primary DMEK group (P [ .1). Mean CCT decreased significantly in both groups 1 month after DMEK (P < .05). Mean ECD and change of ECD did not differ significantly between both groups at each visit (P > .05). CONCLUSION: The results after DMEK as a procedure to treat graft failure after DSAEK were as good as in patients that underwent DMEK as primary intervention to treat advanced Fuchs dystrophy. This indicates that the optical quality can be reestablished by DMEK in patients with failed DSAEK. (Am J Ophthalmol 2015;159(6): 1050–1057. Ó 2015 by Elsevier Inc. All rights reserved.)
Supplemental Material available at AJO.com. Accepted for publication Mar 11, 2015. From the Department of Ophthalmology, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany. Bjo¨rn Bachmann is now affiliated with the Department of Ophthalmology, University of Cologne, Cologne, Germany. Inquiries to Julia M. Weller, Department of Ophthalmology, University of Erlangen-Nuremberg, Schwabachanlage 6 - 91054 Erlangen, Germany; e-mail: [email protected]
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P
OSTERIOR LAMELLAR TECHNIQUES FOR CORNEAL
transplantation allow the replacement of diseased corneal endothelium by healthy donor tissue while the recipient’s corneal stroma is left in place. The main difference among current techniques for posterior lamellar keratoplasty is the composition of the graft. In Descemet stripping automated endothelial keratoplasty (DSAEK) the graft consists of healthy donor endothelium, corresponding Descemet membrane, and parts of the donor’s posterior corneal stroma,1 whereas in Descemet membrane endothelial keratoplasty (DMEK) the graft consists of healthy donor endothelial cells and Descemet membrane only.2–4 The functional outcome of DMEK surgery benefits from the use of a very thin graft: recent work has shown that transplantation of such thin grafts not only results in faster visual rehabilitation but also ends in better visual acuity.5 Better outcomes after DMEK might be attributable to reduced higher-order aberrations of the posterior surface, which might be explained by the re-formation of a physiologic interface between posterior stroma and Descemet membrane after DMEK.6 The ease of graft preparation and transplantation as well as a fast visual rehabilitation have made DSAEK the preferred procedure for the treatment of diseased corneal endothelium; it has replaced penetrating keratoplasty in many parts of the world. In case of graft failure after DSAEK, repeat DSAEK has been shown to be a reasonable therapeutic option.7,8 Since visual quality is better after DMEK,5 DSAEK surgeons are confronted with the question whether DMEK after failed DSAEK might be superior to repeat DSAEK because of better functional outcome. It has been shown by Dirisamer and associates9 and Ham and associates10 that DMEK is technically possible in eyes following DSAEK with unsatisfactory visual results. However, in eyes with corneal decompensation after graft failure, DMEK is more difficult to perform because of poor visibility of the anterior chamber in corneal edema. The question whether DMEK is feasible and successful in these eyes has, to our knowledge, not been addressed. Recent findings provide evidence that adhesion of Descemet membrane to the posterior stroma is mediated by the interaction of a variety of adhesive glycoproteins
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such as fibronectin and vitronectin in the interfacial matrix with stromal proteins.11 Descemet stripping during DMEK exposes the posterior corneal stroma while the interfacial matrix remains at the cleavage plane of the transplanted endothelium–Descemet membrane complex. DSAEK might possibly modify the stromal proteins and thereby impair the adhesion of the graft in DMEK for failed DSAEK. Moreover, removal of the failed DSAEK graft might modify the posterior stromal surface and thus possibly induce optical aberrations. Thereby, the optical quality of the host-graft junction after DMEK for failed DSAEK might be reduced. To examine the suitability of DMEK after failed DSAEK we analyzed the clinical and morphologic outcome of all cases with graft failure after DSAEK that were treated with secondary DMEK compared to patients with primary DMEK surgery.
PATIENTS AND METHODS PATIENTS:
The study group (DMEK after DSAEK group) of this retrospective cohort study consisted of 15 consecutive eyes from 15 patients (mean age: 67.3 6 10.2 years, male: n ¼ 5, female: n ¼ 10) in which DMEK was performed for the treatment of graft failure following DSAEK using a standardized technique for graft preparation and transplantation.12 The indication for DSAEK was Fuchs corneal dystrophy in 14 patients (93%) and pseudophakic bullous keratopathy in 1 patient (7%). All corneas following failed DSAEK showed corneal decompensation with stromal edema. The reason for graft failure was not clear in all our patients. A presumed immunologic rejection was present in 2 eyes. All DSAEK surgeries were performed between October 2006 and December 2011, all secondary DMEK surgeries between October 6, 2009 and February 2, 2013. All surgeries (DMEK and DSAEK), which were performed in our department, were carried out by 3 experienced surgeons. The surgeons had similar learning curves and were experienced with the technique. DMEK surgeries included in this study were not among the first 75 DMEKs of each surgeon. Our regular cohort of patients undergoing primary DMEK tends to have better values of best-corrected visual acuity (BCVA) before DMEK compared to our cohort undergoing DMEK for graft failure after DSAEK (DMEK after DSAEK group). In previous studies, patients undergoing DMEK had a preoperative BCVA between 0.6 and 0.7 logMAR (logarithm of the minimal angle of resolution);5,13,14 that is, BCVA was distinctly better than in the patients undergoing DMEK for failed DSAEK in the current study (1.27 6 0.34 logMAR). Unpublished analysis of our general DMEK cohort showed a significant correlation between preoperative BCVA and BCVA 1, 3, 6, and 12 months after DMEK (n ¼ 216, Spearman VOL. 159, NO. 6
correlation coefficient 1 month: r 0.281, P < .001, 12 months: r 0.274, P ¼ .005; Supplemental Figure, available at AJO.com). Therefore, we compared the patients of the DMEK after DSAEK group retrospectively with 15 consecutive patients with a similarly low preoperative BCVA undergoing primary DMEK for Fuchs endothelial dystrophy. The control group (Primary DMEK group) consisted of 15 eyes from 15 patients undergoing primary DMEK for Fuchs corneal dystrophy (mean age: 71.3 6 10.6 years, P ¼ .233, Mann-Whitney U). The primary DMEK surgeries were performed between September 8, 2009 and February 27, 2013. Mean follow-up time after DMEK was 14.9 6 10.6 months (range 1.0–31.2 months) in the DMEK after DSAEK group and 18.5 6 9.1 months (range 1.0–30.8 months) in the Primary DMEK group (P ¼ .436, Mann-Whitney U). Donor corneas were stored in short-term culture (DMEK after DSAEK group: n ¼ 3, primary DMEK group: n ¼ 5) or long-term organ culture (DMEK after DSAEK group: n ¼ 12, primary DMEK group: n ¼ 10). DMEK grafts were prepared on the day of surgery directly prior to transplantation by the surgeon himself. Informed consent was obtained from the patients. The study complied with the tenets of the Declaration of Helsinki and adhered to all state laws of the country. The Institutional Review Board of the University of ErlangenNuremberg, Germany waived the need for approval. SURGICAL TECHNIQUE:
Graft preparation and graft transplantation for DMEK were performed as previously described in detail.12 The failed DSAEK grafts were removed from the stroma using an inverted hook (Price endothelial keratoplasty hook; Moria SA, Antony, France) and extracted with a forceps (DMEK after DSAEK group). In primary DMEK, the Descemet membrane of the recipient was removed in a central 9-mm area. After stripping, the graft (Descemet membrane with adherent corneal endothelial cells) spontaneously formed a roll, which was injected into the anterior chamber and positioned by repeated injections of balanced salt solution and air bubbles. At the end of the procedure, the anterior chamber was filled with an air bubble, which was reduced to 50% of the anterior chamber volume after 60 minutes. CLINICAL EVALUATION:
The parameters analyzed in this study included BCVA, central corneal thickness (CCT) (Pentacam; Oculus, Wetzlar, Germany), and endothelial cell density (ECD) (SeaEagle; Rhine-Tec GmbH, Krefeld, Germany). The need for additional intracameral air injections after DMEK was assessed at slit-lamp examination and by the use of slit-lamp optical coherence tomography (SL-OCT; Heidelberg Engineering, Heidelberg, Germany). Examination results from the day before DMEK as well as 1, 3, 6, 12, and 18 months after grafting were analyzed.
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TABLE 1. Best-Corrected Visual Acuity Before and 1, 3, 6, 12, and 18 Months After Secondary Descemet Membrane Endothelial Keratoplasty for Graft Failure Following Descemet Stripping Automated Endothelial Keratoplasty and After Primary Descemet Membrane Endothelial Keratoplasty, Respectively Follow-up (Months After
DMEK After DSAEK Group
Primary DMEK Group (Mean 6 SD,
P Value
DMEK)
(Mean 6 SD, logMAR)
logMAR)
(Mann-Whitney U)
Preoperative 1 3 6 12 18
1.27 6 0.34 0.43 6 0.33 0.23 6 0.21 0.19 6 0.05 0.19 6 0.08 0.14 6 0.14
1.0 6 0.40 0.32 6 0.09 0.29 6 0.23 0.19 6 0.07 0.13 6 0.09 0.10 6 0.09
.065 .733 .247 1.0 .429 .731
DMEK ¼ Descemet membrane endothelial keratoplasty; DSAEK ¼ Descemet stripping automated endothelial keratoplasty; logMAR ¼ logarithm of the minimal angle of resolution.
HISTOLOGIC ANALYSIS:
Removed DSAEK grafts were fixed in buffered 10% formaldehyde solution (pH 7.2), dehydrated, and embedded in paraffin. Serial sections cut at 5 mm were stained with hematoxylin-eosin and periodic acid–Schiff. Main criteria of the histologic analyses included thickness of the DSAEK graft at the thickest and thinnest part, endothelial cell count per high-power field, loss of keratocytes, and occurrence of retained Descemet membrane, retrocorneal membranes, infectious infiltrates, inflammatory cells, or melanin granules.
FIGURE 1. Best-corrected visual acuity after Descemet membrane endothelial keratoplasty. Box plot showing bestcorrected visual acuity at baseline and at 5 follow-up visits within the first 18 months after Descemet membrane endothelial keratoplasty (DMEK): comparison between the DMEK after DSAEK (Descemet stripping automated endothelial keratoplasty) group and the Primary DMEK group. The increase in visual acuity was significant in both groups between baseline (preoperatively) and the follow-up visit after 1 and 3 months, respectively. There were no significant differences in mean BCVA at each visit between both groups. Significant differences between 2 groups are marked by an asterisk.
TRANSMISSION ELECTRON MICROSCOPY:
For electron microscopy, 1 explanted DSAEK graft was processed according to standard protocols, as described previously.11 The ultrathin sections were examined with a transmission electron microscope (EM 906E; Carl Zeiss AG, Oberkochen, Germany). STATISTICAL
ANALYSIS: Statistical evaluation was performed using IBM SPSS software version 20.0 (SPSS, Armonk, New York, USA). Differences of samples between groups were assessed by Mann-Whitney U test. Categorical data were analyzed with x2 test and Fisher exact test, if the expected value of each group was less than 5. Differences of parameter values within groups were assessed using the Wilcoxon test. The significance level was set at P ¼ .05.
RESULTS VISUAL ACUITY:
The average time between DSAEK and DMEK was 26 6 17 months (range: 4–70 months). DMEK surgery was successful in all procedures. No primary graft failure occurred. Corneal edema, thickening, and
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opacification of the cornea improved in all patients after DMEK. Four eyes in the DMEK after DSAEK group were excluded from the analysis of the visual acuity owing to amblyopia, ischemic optic neuropathy, macular pucker, and age-related macular degeneration. In the Primary DMEK group 4 eyes were excluded because of epithelial basement membrane dystrophy (Map-dot-fingerprint), subepithelial haze/scarring (n ¼ 2), and a macular hole. There was no difference in the number of eyes with ocular comorbidities limiting the visual acuity in both groups (Fisher exact test, P ¼ .659). Mean BCVA in the DMEK after DSAEK group was 1.27 6 0.34 before DMEK and increased significantly, to 0.43 6 0.33 (Wilcoxon, P ¼ .003) at 1 month and to 0.23 6 0.21 (Wilcoxon, P ¼ .012) at 3 months after DMEK (Table 1). At the following visits 6, 12, and 18 months after DMEK, mean BCVA did not increase significantly compared to the previous visit (P > .05). In the Primary DMEK group, mean BCVA increased significantly from 1.0 6 0.40 before surgery to 0.32 6 0.09 (Wilcoxon, P ¼ .027) 1 month and to 0.29 6 0.23 (Wilcoxon, P ¼ .042) 3 months
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TABLE 2. Central Corneal Thickness Measured Using Pentacam Before and 1, 3, 6, 12, and 18 Months After Secondary Descemet Membrane Endothelial Keratoplasty for Graft Failure Following Descemet Stripping Automated Endothelial Keratoplasty and After Primary Descemet Membrane Endothelial Keratoplasty, Respectively Follow-up (Months After
DMEK After DSAEK Group
Primary DMEK Group (Thickness
DMEK)
(Thickness in mm 6 SD)
in mm 6 SD)
P Value
Preoperative 1 3 6 12 18
917 6 184 480 6 68 479 6 51 480 6 60 520 6 63 506 6 66
727 6 79 506 6 61 522 6 88 505 6 43 520 6 51 512 6 35
N/Aa .247 .18 .299 1.0 .529
DMEK ¼ Descemet membrane endothelial keratoplasty; DSAEK ¼ Descemet stripping automated endothelial keratoplasty. a Preoperative central corneal thickness cannot be compared statistically because corneal thickness after DSAEK is artificially increased by the additional graft tissue.
postoperatively (Table 1). Thereafter, mean BCVA increased slightly but not significantly up to 0.10 6 0.09 at the follow-up visit 18 months after surgery (P > .05). Comparative analysis of mean BCVA values at baseline and at each follow-up visit showed no significant differences between both groups (Table 1, Figure 1). CENTRAL CORNEAL THICKNESS:
In the DMEK after DSAEK group, mean CCT decreased significantly, from 917 6 184 mm before DMEK to 480 6 68 mm 1 month after DMEK (Wilcoxon, P ¼ .005), and in the Primary DMEK group from 727 6 79 mm to 506 6 61 mm (Wilcoxon, P ¼ .018, Table 2). There was no significant difference in CCT at each follow-up visit after DMEK surgery between both groups. During the following months no significant change in mean CCT could be observed within both groups (P > .05 between each follow-up visit, Table 2, Figure 2). ENDOTHELIAL CELL DENSITY:
Mean ECD decreased by 39%, from 2470 6 120 cells/mm2 to 1496 6 311 cells/ mm2, in the DMEK after DSAEK group (P ¼ .005, Wilcoxon) within the first month after surgery. In the Primary DMEK group, mean ECD decreased by 45%, from 2455 6 181 cells/mm2 to 1341 6 201 cells/mm2 (P ¼ .043, Wilcoxon) within the first month after surgery. During the following months mean ECD did not change significantly. There was no significant difference in the endothelial cell counts between both groups at baseline and at each follow-up examination (Table 3, Figure 3). REBUBBLING RATE:
In the DMEK after DSAEK group, 13 eyes showed complete graft attachment during the
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FIGURE 2. Central corneal thickness after Descemet membrane endothelial keratoplasty. Box plot showing central corneal thickness at baseline and at 5 follow-up visits within the first 18 months after Descemet membrane endothelial keratoplasty (DMEK): comparison between the DMEK after DSAEK (Descemet stripping automated endothelial keratoplasty) group and the Primary DMEK group. The decrease in central corneal thickness was significant in both groups between baseline (preoperatively) and the follow-up visit 1 month after surgery. There were no significant differences in the CCT at the following visits between both groups. Significant differences between 2 groups are marked by an asterisk.
postoperative follow-up. Two patients developed a partial graft detachment necessitating rebubblings. One of them received 1 additional air injection into the anterior chamber 7 days after grafting. The other patient received 3 rebubblings (6, 28, and 42 days after DMEK). In the Primary DMEK group, 9 eyes had a complete graft attachment after DMEK, whereas 6 eyes required rebubblings (1 additional air injection, n ¼ 4; 2 injections, n ¼ 1; 3 injections, n ¼ 1) 5–26 days after DMEK surgery. Statistical analysis of the rebubbling rate is not applicable because of the small sample size. HISTOLOGY: Analysis of the morphology using light microscopy was performed in 7 specimens. The average thickness of the graft was 93 6 69 mm (range: 20–200 mm) at the thinnest location and 303 6 132 mm (range: 140–450 mm) at the thickest location. The endothelial cell count was between 0 and 12 endothelial cells per high-power field (mean: 4). A retained recipient’s Descemet membrane was found in 3 cases. Figure 4 (Top left) shows a portion of a DSAEK graft with attenuation of endothelial cells and retained
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Descemet membrane. The recipient’s Descemet membrane is characterized by guttae attributable to Fuchs corneal dystrophy, which was the reason for the grafting (Figure 4, Top left, short arrow). Additionally, in this corneal specimen we found fibrocellular tissue on the stromal side at the edge of the graft (Figure 4, Top left, asterisk). The endothelial cells have migrated onto the edge with formation of a new basement membrane (‘‘thin Descemet membrane,’’ Figure 4, Top left, long arrow). The collagen fibers appeared irregularly in the adjacent stroma, consistent with a stromal scar. The density of keratocytes within the DSAEK graft was reduced in 3 grafts; a complete loss was seen in another 3 specimens. Melanin granules were found in 2 specimens between the retained Descemet membrane and the graft and in 1 specimen within the stromal portion of the graft around keratocytes (Figure 4, Top right). There were no signs of inflammatory reaction, retrocorneal membrane, or infectious infiltrates in the tissues. Transmission electron microscopy of 1 explanted DSAEK graft showing retained Descemet membrane revealed extensive abnormal collagen inclusions in the posterior nonbanded layer of both the recipient’s and, to a lesser extent, the donor’s Descemet membrane (Figure 4, Bottom, arrow). Furthermore, pigment-loaded fibroblastic endothelial cells could be visualized between the retained Descemet membrane and the stromal part of the DSAEK graft (Figure 4, Bottom left, arrowhead). A prominent posterior collagenous layer with few fibroblastlike endothelial cells could be observed on the posterior surface of the graft (Figure 4, Bottom right, arrowhead).
DISCUSSION THE RESULTS OF THIS STUDY CLEARLY INDICATE THAT
DMEK is a suitable procedure for treatment of eyes with corneal decompensation following failed DSAEK. There are 2 studies investigating DMEK in eyes after previous DSAEK.9,10 However, in contrast to our study, which focused on failed DSAEK, the authors analyzed the clinical outcome after DMEK in eyes with functioning DSAEK: Ham and associates published a case series with 3 eyes that were treated with DMEK to improve vision in eyes with functioning DSAEK.10 The indication for secondary DMEK was not defined as corneal decompensation attributable to graft failure, but rather as poor outcome with a visual acuity between 20/80 and 20/40. In this study, the CCT before DMEK was between 559 mm and 670 mm, which can be considered as normal after DSAEK. The second study was very similar and again investigated the clinical outcome of secondary DMEK for poor visual function after DSAEK.9 Mean BCVA before DMEK ranged from 20/100 to 20/40 in 11 eyes; only 1 eye had a visual acuity that was worse (1/60). Average CCT was 670 6 112 mm 1054
TABLE 3. Endothelial Cell Density of the Donor Graft and 1, 3, 6, 12, and 18 Months After Secondary Descemet Membrane Endothelial Keratoplasty for Graft Failure Following Descemet Stripping Automated Endothelial Keratoplasty and After Primary Descemet Membrane Endothelial Keratoplasty, Respectively Follow-up (Months After
DMEK After DSAEK Group (Cell
Primary DMEK Group (Cell
P Value
DMEK)
Count/mm2 6 SD)
Count/mm2 6 SD)
(Mann-Whitney U)
2470 6 120 1496 6 311 1545 6 294 1611 6 265 1393 6 223 1390 6 239
2455 6 181 1341 6 201 1591 6 193 1519 6 272 1499 6 306 1391 6 193
.683 .428 .573 .679 .536 1.00
Donor 1 3 6 12 18
DMEK ¼ Descemet membrane endothelial keratoplasty; DSAEK ¼ Descemet stripping automated endothelial keratoplasty.
in this study population. Therefore, the limitations in visual acuity leading to DMEK in these 2 studies were increased higher-order aberrations attributable to microkeratome-caused irregularities in the posterior corneal surface after DSAEK, but not attributable to graft decompensation.9,10 In contrast, our study showed that mean BCVA before DMEK was 1.27 6 0.34 with pachymetry values between 639 mm and 1172 mm (917 6 184 mm), underlining the state of corneal decompensation owing to malfunction of the DSAEK graft. A general suitability of DMEK for the treatment of eyes with failed DSAEK cannot be deduced by the case series by Ham, because the authors did not include cases of corneal decompensation that may lead to significant alterations of the stroma, such as a stromal remodeling with subepithelial fibrosis.15,16 Ham and associates suggested a ‘‘2-step approach’’ in cases with severe corneal decompensation: The first step is to perform a re-DSAEK for failed DSAEK to achieve de-swelling of the cornea. The second step is to perform a DMEK for visual improvement. To support the ‘‘2-step approach’’ they argued that DMEK is not possible in cases of severe corneal edema owing to poor visibility of the anterior chamber. The main surgical limitation of DMEK as a therapeutic option for failed DSAEK is the reduced visibility of the anterior chamber because of corneal edema. In DMEK, the visibility of the anterior chamber must be better than in DSAEK, because the DMEK graft needs to be unfolded within the anterior chamber and the orientation of the graft is more difficult to determine. The techniques we use to improve the visibility of the anterior chamber are: (1) mechanical removal of the edematous corneal epithelium; (2) application of methylcellulose on the corneal surface during surgery; (3) optimal
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FIGURE 3. Endothelial cell density after Descemet membrane endothelial keratoplasty. Box plot showing the endothelial cell count at baseline and at 5 follow-up visits within the first 18 months after Descemet membrane endothelial keratoplasty (DMEK): comparison between the DMEK after DSAEK (Descemet stripping automated endothelial keratoplasty) group and the Primary DMEK group. The decrease in the endothelial cell count was significant in both groups between baseline (preoperatively) and the follow-up visit 1 month after surgery. The endothelial cell count remained stable afterwards. There were no significant differences in the endothelial cell count at all visits between both groups. Significant differences between 2 groups are marked by an asterisk.
illumination; and (4) increased staining of the graft with trypan blue. Using these techniques, we showed not only that DMEK is possible in eyes with severe corneal edema but also that this procedure renders very good visual results. However, DSAEK is still a very good option if decreased visibility of the anterior chamber makes DMEK impossible. In cases with stromal scarring owing to longstanding corneal edema, penetrating keratoplasty is a good method of choice for visual rehabilitation. Baydoun and associates recently published a retrospective case series study with 17 eyes undergoing repeat DMEK.17 The reason for repeat DMEK was corneal decompensation following graft detachment or graft failure after initial DMEK. The authors provided evidence for the feasibility of repeat DMEK. Visual acuity increased but was not as good as in their cohort of primary DMEK surgeries. Price and Price discussed the question about the best time for repeat DMEK in a recently published editorial:18 In longstanding corneal edema, stromal fibrosis and anterior surface irregularities might occur that limit the visual outcome of repeat DMEK. Therefore, they recommend VOL. 159, NO. 6
repeat DMEK if the graft does not attach or clear within 1 month after DMEK. The histologic findings of our study obtained in order to determine the reason for DSAEK failure are consistent with the literature: Suh and associates examined 19 corneal specimens from patients with failed DSAEK. They observed a loss of endothelial cells (84%), presence of fibrocellular tissue on the stromal surface (58%), retained Descemet membrane on the stromal surface (26%), epithelial ingrowth (21%), and eccentric trephination of the donor tissue (21%).19 Apart from the loss of endothelial cells, we also found retained Descemet membrane and eccentric trephination with a wide range of graft thickness in our patients. In contrast to our study, the majority of the patients reported by Suh and associates had pseudophakic bullous keratopathy and only 3 of them suffered from Fuchs corneal dystrophy as indication for the primary graft. Because of the differences regarding the alterations of the extracellular matrix and adhesion molecules between Descemet membrane and stroma in Fuchs corneal dystrophy and pseudophakous bullous keratopathy,20 the findings cannot be compared directly. Similar histologic findings after failed DSAEK were described by Oster and associates.21 Furthermore, they described a loss of keratocytes in the stromal portion of the graft in 2 out of 16 specimens. Additional findings by Shulman and associates were stromal inflammation (68%), retrocorneal membrane (36%), and immunoreactivity for herpes simplex virus type 1 (14%) in an analysis of 22 failed DSAEK grafts.22 Fungal infections in the interface have been described by Zhang and associates in 2 of 47 analyzed cases.23 In our study there were no signs of an inflammatory reaction. Studies describing DMEK for functioning DSAEK have not analyzed the removed DSAEK grafts histologically.9,10 Interestingly, Dirisamer and associates described that they observed remnants of recipient’s Descemet membrane under air filling during DMEK surgery in 50% of the eyes,9 consistent with our histologic findings. Since nonadhesion of the graft is one of the main challenges after DMEK, we intended to answer the question how well a DMEK graft attaches to the exposed stroma after removal of the failed DSAEK graft. Our previous histologic findings indicated that the splitting between Descemet membrane and the posterior stroma occurs in the cleavage plane between the interfacial matrix of Descemet membrane and the posterior stroma.11,24 Both the interfacial matrix and the posterior stromal layers were found to exhibit various glycoproteins that might be instrumented for the adhesion of the graft. When a DSAEK lamella is detached surgically it seems that the normal posterior stromal surface is exposed. Although the difference in the rebubbling rate was high (13% vs 40%), it did not reach statistical significance. This is primarily owing to the small sample size. The clinically significant difference could be attributed to differences in
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FIGURE 4. Photomicrographs showing the histology of removed grafts after failed Descemet stripping automated endothelial keratoplasty. (Top left) Photomicrograph showing reduced endothelial cell count, retained Descemet membrane on the stromal side of the graft (short arrow), and fibrocellular tissue on the stromal side at the edge of the graft (asterisk). Formation of a new basement membrane (‘‘thin Descemet membrane’’) can be seen at the edge of the graft (long arrow). The collagen fibers are aligned irregularly in the adjacent stroma (periodic acid–Schiff; original magnification: 3200; scale bar [ 100 mm). (Top right) Photomicrograph showing retained Descemet membrane of the recipient (short arrow), melanin granules in the interface (long arrow), and reduced number of keratocytes within the graft (periodic acid–Schiff; original magnification: 3200; scale bar [ 50 mm). (Bottom left) Transmission electron micrograph of the removed failed graft after Descemet stripping automated endothelial keratoplasty with retained recipient’s Descemet membrane shows extensive abnormal collagen inclusions in the posterior nonbanded layer (PNBL) of Descemet membrane (arrow), a posterior collagenous layer (PCL) with remaining pigment-loaded fibroblastic endothelial cells (arrowhead), and subjacent donor corneal stroma (S). (Bottom right) Transmission electron micrograph of the donor’s Descemet membrane shows moderate abnormal collagen inclusions in the PNBL of Descemet membrane (arrow), a prominent PCL with a flat remaining fibroblastic endothelial cell (arrowhead), and overlying donor corneal stroma (S).
culture conditions or to altered adhesive properties of the recipient’s stroma after previous DSAEK. Larger studies and structural examinations are necessary to elucidate this question. The small cohort size is the major limitation of this study and attenuates the value of the study. Larger studies might be necessary to definitely determine the success of DMEK for the treatment of corneal decompensation following failed DSAEK. However, to reach a statistical power of 0.9 for the comparison of BCVA, a sample size of several
hundred patients is necessary. Within a reasonable period this can only be reached by a multicenter study, which in turn is biased by different surgeons and surgical techniques. In conclusion, this study shows the suitability of DMEK surgery not only for poor visual outcome owing to irregularities of the posterior surface after previous DSAEK surgery but also for severe endothelial decompensation with stromal and epithelial edema. DMEK for failed DSAEK renders surgical feasibility, adhesion of the graft, and good optical quality.
ALL AUTHORS HAVE COMPLETED AND SUBMITTED THE ICMJE FORM FOR DISCLOSURE OF POTENTIAL CONFLICTS OF INTEREST. The authors report no financial disclosures. Funding support was provided by grants from DFG (German Research Foundation, Germany) to U. Schlo¨tzerSchrehardt. The study data and the interpretation of the data are independent of this funding. All authors attest that they meet the current ICMJE requirements to qualify as authors.
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REFERENCES 1. Gorovoy MS. Descemet-stripping automated endothelial keratoplasty. Cornea 2006;25(8):886–889. 2. Melles GR, Ong TS, Ververs B, van der Wees J. Descemet membrane endothelial keratoplasty (DMEK). Cornea 2006; 25(8):987–990. 3. Melles GR. Posterior lamellar keratoplasty: DLEK to DSEK to DMEK. Cornea 2006;25(8):879–881. 4. Melles GR, Ong TS, Ververs B, van der Wees J. Preliminary clinical results of Descemet membrane endothelial keratoplasty. Am J Ophthalmol 2008;145(2):222–227. 5. Tourtas T, Laaser K, Bachmann BO, Cursiefen C, Kruse FE. Descemet membrane endothelial keratoplasty versus descemet stripping automated endothelial keratoplasty. Am J Ophthalmol 2012;153(6):1082–1090. 6. Rudolph M, Laaser K, Bachmann BO, Cursiefen C, Epstein D, Kruse FE. Corneal higher-order aberrations after Descemet’s membrane endothelial keratoplasty. Ophthalmology 2012; 119(3):528–535. 7. Gorovoy MS, Meisler DM, Dupps WJ Jr. Late repeat Descemet-stripping automated endothelial keratoplasty. Cornea 2008;27(2):238–240. 8. Letko E, Price DA, Lindoso EM, Price MO, Price FW Jr. Secondary graft failure and repeat endothelial keratoplasty after Descemet’s stripping automated endothelial keratoplasty. Ophthalmology 2011;118(2):310–314. 9. Dirisamer M, Parker J, Naveiras M, et al. Identifying causes for poor visual outcome after DSEK/DSAEK following secondary DMEK in the same eye. Acta Ophthalmol 2013; 91(2):131–139. 10. Ham L, Dapena I, van der Wees J, Melles GR. Secondary DMEK for poor visual outcome after DSEK: donor posterior stroma may limit visual acuity in endothelial keratoplasty. Cornea 2010;29(11):1278–1283. 11. Schlo¨tzer-Schrehardt U, Bachmann BO, Laaser K, Cursiefen C, Kruse FE. Characterization of the cleavage plane in Descemet’s membrane endothelial keratoplasty. Ophthalmology 2011;118(10):1950–1957. 12. Kruse FE, Laaser K, Cursiefen C, et al. A stepwise approach to donor preparation and insertion increases safety and outcome of Descemet’s membrane endothelial keratoplasty. Cornea 2011;30(5):580–587. 13. Laaser K, Bachmann BO, Horn FK, Schlo¨tzer-Schrehardt U, Cursiefen C, Kruse FE. Donor tissue culture conditions and
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14.
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outcome after descemet membrane endothelial keratoplasty. Am J Ophthalmol 2011;151(6):1007–1018. Laaser K, Bachmann BO, Horn FK, Cursiefen C, Kruse FE. Descemet membrane endothelial keratoplasty combined with phacoemulsification and intraocular lens implantation: advanced triple procedure. Am J Ophthalmol 2012;154(1): 47–55. Morishige N, Yamada N, Teranishi S, Chikama T, Nishida T, Takahara A. Detection of subepithelial fibrosis associated with corneal stromal edema by second harmonic generation imaging microscopy. Invest Ophthalmol Vis Sci 2009;50(7): 3145–3150. Eagle RC Jr, Laibson PR, Arentsen JJ. Epithelial abnormalities in chronic corneal edema: a histopathological study. Trans Am Ophthalmol Soc 1989;87:107–119. Baydoun L, van Dijk K, Dapena I, et al. Repeat Descemet membrane endothelial keratoplasty after complicated primary Descemet membrane endothelial keratoplasty. Ophthalmology 2015;122(1):8–16. Price FW Jr, Price MO. To intervene or not to intervene: that is the question. Ophthalmology 2015;122(1):6–7. Suh LH, Dawson DG, Mutapcic L, et al. Histopathologic examination of failed grafts in descemet’s stripping with automated endothelial keratoplasty. Ophthalmology 2009;116(4): 603–608. Weller JM, Zenkel M, Schlo¨tzer-Schrehardt U, Bachmann BO, Tourtas T, Kruse FE. Extracellular matrix alterations in late-onset Fuchs’ corneal dystrophy. Invest Ophthalmol Vis Sci 2014;55(6):3700–3708. Oster SF, Ebrahimi KB, Eberhart CG, Schein OD, Stark WJ, Jun AS. A clinicopathologic series of primary graft failure after Descemet’s stripping and automated endothelial keratoplasty. Ophthalmology 2009;116(4):609–614. Shulman J, Kropinak M, Ritterband DC, et al. Failed descemet-stripping automated endothelial keratoplasty grafts: a clinicopathologic analysis. Am J Ophthalmol 2009; 148(5):752–759. Zhang Q, Randleman JB, Stulting RD, et al. Clinicopathologic findings in failed descemet stripping automated endothelial keratoplasty. Arch Ophthalmol 2010;128(8): 973–980. Schlo¨tzer-Schrehardt U, Bachmann BO, Tourtas T, et al. Reproducibility of graft preparations in Descemet’s membrane endothelial keratoplasty. Ophthalmology 2013;120(9): 1769–1777.
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Biosketch Julia M. Weller graduated from Medical School of the University of Erlangen-Nuremberg, Germany in 2010. She is a member of the Department of Ophthalmology at the University of Erlangen-Nuremberg, Germany. Her research interests include corneal endothelial transplantation and the pathophysiology of Fuchs’ endothelial corneal dystrophy.
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SUPPLEMENTAL FIGURE. Correlation between bestcorrected visual acuity (BCVA) preoperatively and 1 month after Descemet membrane endothelial keratoplasty (DMEK) in the general cohort of Descemet membrane endothelial keratoplasties of the Department of Ophthalmology, University Erlangen-Nuremberg, Germany (n [ 216, Spearman correlation coefficient 1 month: r 0.281, P < .001, 12 months: r 0.274, P [ .005).
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PURPOSE:
To investigate the outcome of Descemet membrane endothelial keratoplasty (DMEK) in patients with graft failure after Descemet stripping automated endothelial keratoplasty (DSAEK). DESIGN: Retrospective cohort study. METHODS: SETTING: Institutional. STUDY POPULATION: Fifteen eyes of 15 patients that underwent DMEK for graft failure with corneal decompensation following DSAEK were analyzed; 15 eyes with primary DMEK for Fuchs corneal dystrophy were included as control group. MAIN OUTCOME MEASURES: Best-corrected visual acuity (BCVA), endothelial cell density (ECD), central corneal thickness (CCT), and rebubbling rate. RESULTS: DMEK surgery was successful in all cases of both groups. Mean BCVA (logMAR) before DMEK was 1.27 ± 0.34 in the DMEK after DSAEK group and 1.0 ± 0.40 in the Primary DMEK group. After DMEK, mean BCVA increased significantly to 0.23 ± 0.21 (P [ .012, DMEK after DSAEK group) and 0.29 ± 0.23 (P [ .042, Primary DMEK group) after 3 months. There were no significant differences in mean BCVA between both groups at each visit. The rebubbling rate was 13% in the DMEK after DSAEK group and 40% in the Primary DMEK group (P [ .1). Mean CCT decreased significantly in both groups 1 month after DMEK (P < .05). Mean ECD and change of ECD did not differ significantly between both groups at each visit (P > .05). CONCLUSION: The results after DMEK as a procedure to treat graft failure after DSAEK were as good as in patients that underwent DMEK as primary intervention to treat advanced Fuchs dystrophy. This indicates that the optical quality can be reestablished by DMEK in patients with failed DSAEK. (Am J Ophthalmol 2015;159(6): 1050–1057. Ó 2015 by Elsevier Inc. All rights reserved.)
Supplemental Material available at AJO.com. Accepted for publication Mar 11, 2015. From the Department of Ophthalmology, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany. Bjo¨rn Bachmann is now affiliated with the Department of Ophthalmology, University of Cologne, Cologne, Germany. Inquiries to Julia M. Weller, Department of Ophthalmology, University of Erlangen-Nuremberg, Schwabachanlage 6 - 91054 Erlangen, Germany; e-mail: [email protected]
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OSTERIOR LAMELLAR TECHNIQUES FOR CORNEAL
transplantation allow the replacement of diseased corneal endothelium by healthy donor tissue while the recipient’s corneal stroma is left in place. The main difference among current techniques for posterior lamellar keratoplasty is the composition of the graft. In Descemet stripping automated endothelial keratoplasty (DSAEK) the graft consists of healthy donor endothelium, corresponding Descemet membrane, and parts of the donor’s posterior corneal stroma,1 whereas in Descemet membrane endothelial keratoplasty (DMEK) the graft consists of healthy donor endothelial cells and Descemet membrane only.2–4 The functional outcome of DMEK surgery benefits from the use of a very thin graft: recent work has shown that transplantation of such thin grafts not only results in faster visual rehabilitation but also ends in better visual acuity.5 Better outcomes after DMEK might be attributable to reduced higher-order aberrations of the posterior surface, which might be explained by the re-formation of a physiologic interface between posterior stroma and Descemet membrane after DMEK.6 The ease of graft preparation and transplantation as well as a fast visual rehabilitation have made DSAEK the preferred procedure for the treatment of diseased corneal endothelium; it has replaced penetrating keratoplasty in many parts of the world. In case of graft failure after DSAEK, repeat DSAEK has been shown to be a reasonable therapeutic option.7,8 Since visual quality is better after DMEK,5 DSAEK surgeons are confronted with the question whether DMEK after failed DSAEK might be superior to repeat DSAEK because of better functional outcome. It has been shown by Dirisamer and associates9 and Ham and associates10 that DMEK is technically possible in eyes following DSAEK with unsatisfactory visual results. However, in eyes with corneal decompensation after graft failure, DMEK is more difficult to perform because of poor visibility of the anterior chamber in corneal edema. The question whether DMEK is feasible and successful in these eyes has, to our knowledge, not been addressed. Recent findings provide evidence that adhesion of Descemet membrane to the posterior stroma is mediated by the interaction of a variety of adhesive glycoproteins
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such as fibronectin and vitronectin in the interfacial matrix with stromal proteins.11 Descemet stripping during DMEK exposes the posterior corneal stroma while the interfacial matrix remains at the cleavage plane of the transplanted endothelium–Descemet membrane complex. DSAEK might possibly modify the stromal proteins and thereby impair the adhesion of the graft in DMEK for failed DSAEK. Moreover, removal of the failed DSAEK graft might modify the posterior stromal surface and thus possibly induce optical aberrations. Thereby, the optical quality of the host-graft junction after DMEK for failed DSAEK might be reduced. To examine the suitability of DMEK after failed DSAEK we analyzed the clinical and morphologic outcome of all cases with graft failure after DSAEK that were treated with secondary DMEK compared to patients with primary DMEK surgery.
PATIENTS AND METHODS PATIENTS:
The study group (DMEK after DSAEK group) of this retrospective cohort study consisted of 15 consecutive eyes from 15 patients (mean age: 67.3 6 10.2 years, male: n ¼ 5, female: n ¼ 10) in which DMEK was performed for the treatment of graft failure following DSAEK using a standardized technique for graft preparation and transplantation.12 The indication for DSAEK was Fuchs corneal dystrophy in 14 patients (93%) and pseudophakic bullous keratopathy in 1 patient (7%). All corneas following failed DSAEK showed corneal decompensation with stromal edema. The reason for graft failure was not clear in all our patients. A presumed immunologic rejection was present in 2 eyes. All DSAEK surgeries were performed between October 2006 and December 2011, all secondary DMEK surgeries between October 6, 2009 and February 2, 2013. All surgeries (DMEK and DSAEK), which were performed in our department, were carried out by 3 experienced surgeons. The surgeons had similar learning curves and were experienced with the technique. DMEK surgeries included in this study were not among the first 75 DMEKs of each surgeon. Our regular cohort of patients undergoing primary DMEK tends to have better values of best-corrected visual acuity (BCVA) before DMEK compared to our cohort undergoing DMEK for graft failure after DSAEK (DMEK after DSAEK group). In previous studies, patients undergoing DMEK had a preoperative BCVA between 0.6 and 0.7 logMAR (logarithm of the minimal angle of resolution);5,13,14 that is, BCVA was distinctly better than in the patients undergoing DMEK for failed DSAEK in the current study (1.27 6 0.34 logMAR). Unpublished analysis of our general DMEK cohort showed a significant correlation between preoperative BCVA and BCVA 1, 3, 6, and 12 months after DMEK (n ¼ 216, Spearman VOL. 159, NO. 6
correlation coefficient 1 month: r 0.281, P < .001, 12 months: r 0.274, P ¼ .005; Supplemental Figure, available at AJO.com). Therefore, we compared the patients of the DMEK after DSAEK group retrospectively with 15 consecutive patients with a similarly low preoperative BCVA undergoing primary DMEK for Fuchs endothelial dystrophy. The control group (Primary DMEK group) consisted of 15 eyes from 15 patients undergoing primary DMEK for Fuchs corneal dystrophy (mean age: 71.3 6 10.6 years, P ¼ .233, Mann-Whitney U). The primary DMEK surgeries were performed between September 8, 2009 and February 27, 2013. Mean follow-up time after DMEK was 14.9 6 10.6 months (range 1.0–31.2 months) in the DMEK after DSAEK group and 18.5 6 9.1 months (range 1.0–30.8 months) in the Primary DMEK group (P ¼ .436, Mann-Whitney U). Donor corneas were stored in short-term culture (DMEK after DSAEK group: n ¼ 3, primary DMEK group: n ¼ 5) or long-term organ culture (DMEK after DSAEK group: n ¼ 12, primary DMEK group: n ¼ 10). DMEK grafts were prepared on the day of surgery directly prior to transplantation by the surgeon himself. Informed consent was obtained from the patients. The study complied with the tenets of the Declaration of Helsinki and adhered to all state laws of the country. The Institutional Review Board of the University of ErlangenNuremberg, Germany waived the need for approval. SURGICAL TECHNIQUE:
Graft preparation and graft transplantation for DMEK were performed as previously described in detail.12 The failed DSAEK grafts were removed from the stroma using an inverted hook (Price endothelial keratoplasty hook; Moria SA, Antony, France) and extracted with a forceps (DMEK after DSAEK group). In primary DMEK, the Descemet membrane of the recipient was removed in a central 9-mm area. After stripping, the graft (Descemet membrane with adherent corneal endothelial cells) spontaneously formed a roll, which was injected into the anterior chamber and positioned by repeated injections of balanced salt solution and air bubbles. At the end of the procedure, the anterior chamber was filled with an air bubble, which was reduced to 50% of the anterior chamber volume after 60 minutes. CLINICAL EVALUATION:
The parameters analyzed in this study included BCVA, central corneal thickness (CCT) (Pentacam; Oculus, Wetzlar, Germany), and endothelial cell density (ECD) (SeaEagle; Rhine-Tec GmbH, Krefeld, Germany). The need for additional intracameral air injections after DMEK was assessed at slit-lamp examination and by the use of slit-lamp optical coherence tomography (SL-OCT; Heidelberg Engineering, Heidelberg, Germany). Examination results from the day before DMEK as well as 1, 3, 6, 12, and 18 months after grafting were analyzed.
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TABLE 1. Best-Corrected Visual Acuity Before and 1, 3, 6, 12, and 18 Months After Secondary Descemet Membrane Endothelial Keratoplasty for Graft Failure Following Descemet Stripping Automated Endothelial Keratoplasty and After Primary Descemet Membrane Endothelial Keratoplasty, Respectively Follow-up (Months After
DMEK After DSAEK Group
Primary DMEK Group (Mean 6 SD,
P Value
DMEK)
(Mean 6 SD, logMAR)
logMAR)
(Mann-Whitney U)
Preoperative 1 3 6 12 18
1.27 6 0.34 0.43 6 0.33 0.23 6 0.21 0.19 6 0.05 0.19 6 0.08 0.14 6 0.14
1.0 6 0.40 0.32 6 0.09 0.29 6 0.23 0.19 6 0.07 0.13 6 0.09 0.10 6 0.09
.065 .733 .247 1.0 .429 .731
DMEK ¼ Descemet membrane endothelial keratoplasty; DSAEK ¼ Descemet stripping automated endothelial keratoplasty; logMAR ¼ logarithm of the minimal angle of resolution.
HISTOLOGIC ANALYSIS:
Removed DSAEK grafts were fixed in buffered 10% formaldehyde solution (pH 7.2), dehydrated, and embedded in paraffin. Serial sections cut at 5 mm were stained with hematoxylin-eosin and periodic acid–Schiff. Main criteria of the histologic analyses included thickness of the DSAEK graft at the thickest and thinnest part, endothelial cell count per high-power field, loss of keratocytes, and occurrence of retained Descemet membrane, retrocorneal membranes, infectious infiltrates, inflammatory cells, or melanin granules.
FIGURE 1. Best-corrected visual acuity after Descemet membrane endothelial keratoplasty. Box plot showing bestcorrected visual acuity at baseline and at 5 follow-up visits within the first 18 months after Descemet membrane endothelial keratoplasty (DMEK): comparison between the DMEK after DSAEK (Descemet stripping automated endothelial keratoplasty) group and the Primary DMEK group. The increase in visual acuity was significant in both groups between baseline (preoperatively) and the follow-up visit after 1 and 3 months, respectively. There were no significant differences in mean BCVA at each visit between both groups. Significant differences between 2 groups are marked by an asterisk.
TRANSMISSION ELECTRON MICROSCOPY:
For electron microscopy, 1 explanted DSAEK graft was processed according to standard protocols, as described previously.11 The ultrathin sections were examined with a transmission electron microscope (EM 906E; Carl Zeiss AG, Oberkochen, Germany). STATISTICAL
ANALYSIS: Statistical evaluation was performed using IBM SPSS software version 20.0 (SPSS, Armonk, New York, USA). Differences of samples between groups were assessed by Mann-Whitney U test. Categorical data were analyzed with x2 test and Fisher exact test, if the expected value of each group was less than 5. Differences of parameter values within groups were assessed using the Wilcoxon test. The significance level was set at P ¼ .05.
RESULTS VISUAL ACUITY:
The average time between DSAEK and DMEK was 26 6 17 months (range: 4–70 months). DMEK surgery was successful in all procedures. No primary graft failure occurred. Corneal edema, thickening, and
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opacification of the cornea improved in all patients after DMEK. Four eyes in the DMEK after DSAEK group were excluded from the analysis of the visual acuity owing to amblyopia, ischemic optic neuropathy, macular pucker, and age-related macular degeneration. In the Primary DMEK group 4 eyes were excluded because of epithelial basement membrane dystrophy (Map-dot-fingerprint), subepithelial haze/scarring (n ¼ 2), and a macular hole. There was no difference in the number of eyes with ocular comorbidities limiting the visual acuity in both groups (Fisher exact test, P ¼ .659). Mean BCVA in the DMEK after DSAEK group was 1.27 6 0.34 before DMEK and increased significantly, to 0.43 6 0.33 (Wilcoxon, P ¼ .003) at 1 month and to 0.23 6 0.21 (Wilcoxon, P ¼ .012) at 3 months after DMEK (Table 1). At the following visits 6, 12, and 18 months after DMEK, mean BCVA did not increase significantly compared to the previous visit (P > .05). In the Primary DMEK group, mean BCVA increased significantly from 1.0 6 0.40 before surgery to 0.32 6 0.09 (Wilcoxon, P ¼ .027) 1 month and to 0.29 6 0.23 (Wilcoxon, P ¼ .042) 3 months
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TABLE 2. Central Corneal Thickness Measured Using Pentacam Before and 1, 3, 6, 12, and 18 Months After Secondary Descemet Membrane Endothelial Keratoplasty for Graft Failure Following Descemet Stripping Automated Endothelial Keratoplasty and After Primary Descemet Membrane Endothelial Keratoplasty, Respectively Follow-up (Months After
DMEK After DSAEK Group
Primary DMEK Group (Thickness
DMEK)
(Thickness in mm 6 SD)
in mm 6 SD)
P Value
Preoperative 1 3 6 12 18
917 6 184 480 6 68 479 6 51 480 6 60 520 6 63 506 6 66
727 6 79 506 6 61 522 6 88 505 6 43 520 6 51 512 6 35
N/Aa .247 .18 .299 1.0 .529
DMEK ¼ Descemet membrane endothelial keratoplasty; DSAEK ¼ Descemet stripping automated endothelial keratoplasty. a Preoperative central corneal thickness cannot be compared statistically because corneal thickness after DSAEK is artificially increased by the additional graft tissue.
postoperatively (Table 1). Thereafter, mean BCVA increased slightly but not significantly up to 0.10 6 0.09 at the follow-up visit 18 months after surgery (P > .05). Comparative analysis of mean BCVA values at baseline and at each follow-up visit showed no significant differences between both groups (Table 1, Figure 1). CENTRAL CORNEAL THICKNESS:
In the DMEK after DSAEK group, mean CCT decreased significantly, from 917 6 184 mm before DMEK to 480 6 68 mm 1 month after DMEK (Wilcoxon, P ¼ .005), and in the Primary DMEK group from 727 6 79 mm to 506 6 61 mm (Wilcoxon, P ¼ .018, Table 2). There was no significant difference in CCT at each follow-up visit after DMEK surgery between both groups. During the following months no significant change in mean CCT could be observed within both groups (P > .05 between each follow-up visit, Table 2, Figure 2). ENDOTHELIAL CELL DENSITY:
Mean ECD decreased by 39%, from 2470 6 120 cells/mm2 to 1496 6 311 cells/ mm2, in the DMEK after DSAEK group (P ¼ .005, Wilcoxon) within the first month after surgery. In the Primary DMEK group, mean ECD decreased by 45%, from 2455 6 181 cells/mm2 to 1341 6 201 cells/mm2 (P ¼ .043, Wilcoxon) within the first month after surgery. During the following months mean ECD did not change significantly. There was no significant difference in the endothelial cell counts between both groups at baseline and at each follow-up examination (Table 3, Figure 3). REBUBBLING RATE:
In the DMEK after DSAEK group, 13 eyes showed complete graft attachment during the
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FIGURE 2. Central corneal thickness after Descemet membrane endothelial keratoplasty. Box plot showing central corneal thickness at baseline and at 5 follow-up visits within the first 18 months after Descemet membrane endothelial keratoplasty (DMEK): comparison between the DMEK after DSAEK (Descemet stripping automated endothelial keratoplasty) group and the Primary DMEK group. The decrease in central corneal thickness was significant in both groups between baseline (preoperatively) and the follow-up visit 1 month after surgery. There were no significant differences in the CCT at the following visits between both groups. Significant differences between 2 groups are marked by an asterisk.
postoperative follow-up. Two patients developed a partial graft detachment necessitating rebubblings. One of them received 1 additional air injection into the anterior chamber 7 days after grafting. The other patient received 3 rebubblings (6, 28, and 42 days after DMEK). In the Primary DMEK group, 9 eyes had a complete graft attachment after DMEK, whereas 6 eyes required rebubblings (1 additional air injection, n ¼ 4; 2 injections, n ¼ 1; 3 injections, n ¼ 1) 5–26 days after DMEK surgery. Statistical analysis of the rebubbling rate is not applicable because of the small sample size. HISTOLOGY: Analysis of the morphology using light microscopy was performed in 7 specimens. The average thickness of the graft was 93 6 69 mm (range: 20–200 mm) at the thinnest location and 303 6 132 mm (range: 140–450 mm) at the thickest location. The endothelial cell count was between 0 and 12 endothelial cells per high-power field (mean: 4). A retained recipient’s Descemet membrane was found in 3 cases. Figure 4 (Top left) shows a portion of a DSAEK graft with attenuation of endothelial cells and retained
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Descemet membrane. The recipient’s Descemet membrane is characterized by guttae attributable to Fuchs corneal dystrophy, which was the reason for the grafting (Figure 4, Top left, short arrow). Additionally, in this corneal specimen we found fibrocellular tissue on the stromal side at the edge of the graft (Figure 4, Top left, asterisk). The endothelial cells have migrated onto the edge with formation of a new basement membrane (‘‘thin Descemet membrane,’’ Figure 4, Top left, long arrow). The collagen fibers appeared irregularly in the adjacent stroma, consistent with a stromal scar. The density of keratocytes within the DSAEK graft was reduced in 3 grafts; a complete loss was seen in another 3 specimens. Melanin granules were found in 2 specimens between the retained Descemet membrane and the graft and in 1 specimen within the stromal portion of the graft around keratocytes (Figure 4, Top right). There were no signs of inflammatory reaction, retrocorneal membrane, or infectious infiltrates in the tissues. Transmission electron microscopy of 1 explanted DSAEK graft showing retained Descemet membrane revealed extensive abnormal collagen inclusions in the posterior nonbanded layer of both the recipient’s and, to a lesser extent, the donor’s Descemet membrane (Figure 4, Bottom, arrow). Furthermore, pigment-loaded fibroblastic endothelial cells could be visualized between the retained Descemet membrane and the stromal part of the DSAEK graft (Figure 4, Bottom left, arrowhead). A prominent posterior collagenous layer with few fibroblastlike endothelial cells could be observed on the posterior surface of the graft (Figure 4, Bottom right, arrowhead).
DISCUSSION THE RESULTS OF THIS STUDY CLEARLY INDICATE THAT
DMEK is a suitable procedure for treatment of eyes with corneal decompensation following failed DSAEK. There are 2 studies investigating DMEK in eyes after previous DSAEK.9,10 However, in contrast to our study, which focused on failed DSAEK, the authors analyzed the clinical outcome after DMEK in eyes with functioning DSAEK: Ham and associates published a case series with 3 eyes that were treated with DMEK to improve vision in eyes with functioning DSAEK.10 The indication for secondary DMEK was not defined as corneal decompensation attributable to graft failure, but rather as poor outcome with a visual acuity between 20/80 and 20/40. In this study, the CCT before DMEK was between 559 mm and 670 mm, which can be considered as normal after DSAEK. The second study was very similar and again investigated the clinical outcome of secondary DMEK for poor visual function after DSAEK.9 Mean BCVA before DMEK ranged from 20/100 to 20/40 in 11 eyes; only 1 eye had a visual acuity that was worse (1/60). Average CCT was 670 6 112 mm 1054
TABLE 3. Endothelial Cell Density of the Donor Graft and 1, 3, 6, 12, and 18 Months After Secondary Descemet Membrane Endothelial Keratoplasty for Graft Failure Following Descemet Stripping Automated Endothelial Keratoplasty and After Primary Descemet Membrane Endothelial Keratoplasty, Respectively Follow-up (Months After
DMEK After DSAEK Group (Cell
Primary DMEK Group (Cell
P Value
DMEK)
Count/mm2 6 SD)
Count/mm2 6 SD)
(Mann-Whitney U)
2470 6 120 1496 6 311 1545 6 294 1611 6 265 1393 6 223 1390 6 239
2455 6 181 1341 6 201 1591 6 193 1519 6 272 1499 6 306 1391 6 193
.683 .428 .573 .679 .536 1.00
Donor 1 3 6 12 18
DMEK ¼ Descemet membrane endothelial keratoplasty; DSAEK ¼ Descemet stripping automated endothelial keratoplasty.
in this study population. Therefore, the limitations in visual acuity leading to DMEK in these 2 studies were increased higher-order aberrations attributable to microkeratome-caused irregularities in the posterior corneal surface after DSAEK, but not attributable to graft decompensation.9,10 In contrast, our study showed that mean BCVA before DMEK was 1.27 6 0.34 with pachymetry values between 639 mm and 1172 mm (917 6 184 mm), underlining the state of corneal decompensation owing to malfunction of the DSAEK graft. A general suitability of DMEK for the treatment of eyes with failed DSAEK cannot be deduced by the case series by Ham, because the authors did not include cases of corneal decompensation that may lead to significant alterations of the stroma, such as a stromal remodeling with subepithelial fibrosis.15,16 Ham and associates suggested a ‘‘2-step approach’’ in cases with severe corneal decompensation: The first step is to perform a re-DSAEK for failed DSAEK to achieve de-swelling of the cornea. The second step is to perform a DMEK for visual improvement. To support the ‘‘2-step approach’’ they argued that DMEK is not possible in cases of severe corneal edema owing to poor visibility of the anterior chamber. The main surgical limitation of DMEK as a therapeutic option for failed DSAEK is the reduced visibility of the anterior chamber because of corneal edema. In DMEK, the visibility of the anterior chamber must be better than in DSAEK, because the DMEK graft needs to be unfolded within the anterior chamber and the orientation of the graft is more difficult to determine. The techniques we use to improve the visibility of the anterior chamber are: (1) mechanical removal of the edematous corneal epithelium; (2) application of methylcellulose on the corneal surface during surgery; (3) optimal
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FIGURE 3. Endothelial cell density after Descemet membrane endothelial keratoplasty. Box plot showing the endothelial cell count at baseline and at 5 follow-up visits within the first 18 months after Descemet membrane endothelial keratoplasty (DMEK): comparison between the DMEK after DSAEK (Descemet stripping automated endothelial keratoplasty) group and the Primary DMEK group. The decrease in the endothelial cell count was significant in both groups between baseline (preoperatively) and the follow-up visit 1 month after surgery. The endothelial cell count remained stable afterwards. There were no significant differences in the endothelial cell count at all visits between both groups. Significant differences between 2 groups are marked by an asterisk.
illumination; and (4) increased staining of the graft with trypan blue. Using these techniques, we showed not only that DMEK is possible in eyes with severe corneal edema but also that this procedure renders very good visual results. However, DSAEK is still a very good option if decreased visibility of the anterior chamber makes DMEK impossible. In cases with stromal scarring owing to longstanding corneal edema, penetrating keratoplasty is a good method of choice for visual rehabilitation. Baydoun and associates recently published a retrospective case series study with 17 eyes undergoing repeat DMEK.17 The reason for repeat DMEK was corneal decompensation following graft detachment or graft failure after initial DMEK. The authors provided evidence for the feasibility of repeat DMEK. Visual acuity increased but was not as good as in their cohort of primary DMEK surgeries. Price and Price discussed the question about the best time for repeat DMEK in a recently published editorial:18 In longstanding corneal edema, stromal fibrosis and anterior surface irregularities might occur that limit the visual outcome of repeat DMEK. Therefore, they recommend VOL. 159, NO. 6
repeat DMEK if the graft does not attach or clear within 1 month after DMEK. The histologic findings of our study obtained in order to determine the reason for DSAEK failure are consistent with the literature: Suh and associates examined 19 corneal specimens from patients with failed DSAEK. They observed a loss of endothelial cells (84%), presence of fibrocellular tissue on the stromal surface (58%), retained Descemet membrane on the stromal surface (26%), epithelial ingrowth (21%), and eccentric trephination of the donor tissue (21%).19 Apart from the loss of endothelial cells, we also found retained Descemet membrane and eccentric trephination with a wide range of graft thickness in our patients. In contrast to our study, the majority of the patients reported by Suh and associates had pseudophakic bullous keratopathy and only 3 of them suffered from Fuchs corneal dystrophy as indication for the primary graft. Because of the differences regarding the alterations of the extracellular matrix and adhesion molecules between Descemet membrane and stroma in Fuchs corneal dystrophy and pseudophakous bullous keratopathy,20 the findings cannot be compared directly. Similar histologic findings after failed DSAEK were described by Oster and associates.21 Furthermore, they described a loss of keratocytes in the stromal portion of the graft in 2 out of 16 specimens. Additional findings by Shulman and associates were stromal inflammation (68%), retrocorneal membrane (36%), and immunoreactivity for herpes simplex virus type 1 (14%) in an analysis of 22 failed DSAEK grafts.22 Fungal infections in the interface have been described by Zhang and associates in 2 of 47 analyzed cases.23 In our study there were no signs of an inflammatory reaction. Studies describing DMEK for functioning DSAEK have not analyzed the removed DSAEK grafts histologically.9,10 Interestingly, Dirisamer and associates described that they observed remnants of recipient’s Descemet membrane under air filling during DMEK surgery in 50% of the eyes,9 consistent with our histologic findings. Since nonadhesion of the graft is one of the main challenges after DMEK, we intended to answer the question how well a DMEK graft attaches to the exposed stroma after removal of the failed DSAEK graft. Our previous histologic findings indicated that the splitting between Descemet membrane and the posterior stroma occurs in the cleavage plane between the interfacial matrix of Descemet membrane and the posterior stroma.11,24 Both the interfacial matrix and the posterior stromal layers were found to exhibit various glycoproteins that might be instrumented for the adhesion of the graft. When a DSAEK lamella is detached surgically it seems that the normal posterior stromal surface is exposed. Although the difference in the rebubbling rate was high (13% vs 40%), it did not reach statistical significance. This is primarily owing to the small sample size. The clinically significant difference could be attributed to differences in
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FIGURE 4. Photomicrographs showing the histology of removed grafts after failed Descemet stripping automated endothelial keratoplasty. (Top left) Photomicrograph showing reduced endothelial cell count, retained Descemet membrane on the stromal side of the graft (short arrow), and fibrocellular tissue on the stromal side at the edge of the graft (asterisk). Formation of a new basement membrane (‘‘thin Descemet membrane’’) can be seen at the edge of the graft (long arrow). The collagen fibers are aligned irregularly in the adjacent stroma (periodic acid–Schiff; original magnification: 3200; scale bar [ 100 mm). (Top right) Photomicrograph showing retained Descemet membrane of the recipient (short arrow), melanin granules in the interface (long arrow), and reduced number of keratocytes within the graft (periodic acid–Schiff; original magnification: 3200; scale bar [ 50 mm). (Bottom left) Transmission electron micrograph of the removed failed graft after Descemet stripping automated endothelial keratoplasty with retained recipient’s Descemet membrane shows extensive abnormal collagen inclusions in the posterior nonbanded layer (PNBL) of Descemet membrane (arrow), a posterior collagenous layer (PCL) with remaining pigment-loaded fibroblastic endothelial cells (arrowhead), and subjacent donor corneal stroma (S). (Bottom right) Transmission electron micrograph of the donor’s Descemet membrane shows moderate abnormal collagen inclusions in the PNBL of Descemet membrane (arrow), a prominent PCL with a flat remaining fibroblastic endothelial cell (arrowhead), and overlying donor corneal stroma (S).
culture conditions or to altered adhesive properties of the recipient’s stroma after previous DSAEK. Larger studies and structural examinations are necessary to elucidate this question. The small cohort size is the major limitation of this study and attenuates the value of the study. Larger studies might be necessary to definitely determine the success of DMEK for the treatment of corneal decompensation following failed DSAEK. However, to reach a statistical power of 0.9 for the comparison of BCVA, a sample size of several
hundred patients is necessary. Within a reasonable period this can only be reached by a multicenter study, which in turn is biased by different surgeons and surgical techniques. In conclusion, this study shows the suitability of DMEK surgery not only for poor visual outcome owing to irregularities of the posterior surface after previous DSAEK surgery but also for severe endothelial decompensation with stromal and epithelial edema. DMEK for failed DSAEK renders surgical feasibility, adhesion of the graft, and good optical quality.
ALL AUTHORS HAVE COMPLETED AND SUBMITTED THE ICMJE FORM FOR DISCLOSURE OF POTENTIAL CONFLICTS OF INTEREST. The authors report no financial disclosures. Funding support was provided by grants from DFG (German Research Foundation, Germany) to U. Schlo¨tzerSchrehardt. The study data and the interpretation of the data are independent of this funding. All authors attest that they meet the current ICMJE requirements to qualify as authors.
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REFERENCES 1. Gorovoy MS. Descemet-stripping automated endothelial keratoplasty. Cornea 2006;25(8):886–889. 2. Melles GR, Ong TS, Ververs B, van der Wees J. Descemet membrane endothelial keratoplasty (DMEK). Cornea 2006; 25(8):987–990. 3. Melles GR. Posterior lamellar keratoplasty: DLEK to DSEK to DMEK. Cornea 2006;25(8):879–881. 4. Melles GR, Ong TS, Ververs B, van der Wees J. Preliminary clinical results of Descemet membrane endothelial keratoplasty. Am J Ophthalmol 2008;145(2):222–227. 5. Tourtas T, Laaser K, Bachmann BO, Cursiefen C, Kruse FE. Descemet membrane endothelial keratoplasty versus descemet stripping automated endothelial keratoplasty. Am J Ophthalmol 2012;153(6):1082–1090. 6. Rudolph M, Laaser K, Bachmann BO, Cursiefen C, Epstein D, Kruse FE. Corneal higher-order aberrations after Descemet’s membrane endothelial keratoplasty. Ophthalmology 2012; 119(3):528–535. 7. Gorovoy MS, Meisler DM, Dupps WJ Jr. Late repeat Descemet-stripping automated endothelial keratoplasty. Cornea 2008;27(2):238–240. 8. Letko E, Price DA, Lindoso EM, Price MO, Price FW Jr. Secondary graft failure and repeat endothelial keratoplasty after Descemet’s stripping automated endothelial keratoplasty. Ophthalmology 2011;118(2):310–314. 9. Dirisamer M, Parker J, Naveiras M, et al. Identifying causes for poor visual outcome after DSEK/DSAEK following secondary DMEK in the same eye. Acta Ophthalmol 2013; 91(2):131–139. 10. Ham L, Dapena I, van der Wees J, Melles GR. Secondary DMEK for poor visual outcome after DSEK: donor posterior stroma may limit visual acuity in endothelial keratoplasty. Cornea 2010;29(11):1278–1283. 11. Schlo¨tzer-Schrehardt U, Bachmann BO, Laaser K, Cursiefen C, Kruse FE. Characterization of the cleavage plane in Descemet’s membrane endothelial keratoplasty. Ophthalmology 2011;118(10):1950–1957. 12. Kruse FE, Laaser K, Cursiefen C, et al. A stepwise approach to donor preparation and insertion increases safety and outcome of Descemet’s membrane endothelial keratoplasty. Cornea 2011;30(5):580–587. 13. Laaser K, Bachmann BO, Horn FK, Schlo¨tzer-Schrehardt U, Cursiefen C, Kruse FE. Donor tissue culture conditions and
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outcome after descemet membrane endothelial keratoplasty. Am J Ophthalmol 2011;151(6):1007–1018. Laaser K, Bachmann BO, Horn FK, Cursiefen C, Kruse FE. Descemet membrane endothelial keratoplasty combined with phacoemulsification and intraocular lens implantation: advanced triple procedure. Am J Ophthalmol 2012;154(1): 47–55. Morishige N, Yamada N, Teranishi S, Chikama T, Nishida T, Takahara A. Detection of subepithelial fibrosis associated with corneal stromal edema by second harmonic generation imaging microscopy. Invest Ophthalmol Vis Sci 2009;50(7): 3145–3150. Eagle RC Jr, Laibson PR, Arentsen JJ. Epithelial abnormalities in chronic corneal edema: a histopathological study. Trans Am Ophthalmol Soc 1989;87:107–119. Baydoun L, van Dijk K, Dapena I, et al. Repeat Descemet membrane endothelial keratoplasty after complicated primary Descemet membrane endothelial keratoplasty. Ophthalmology 2015;122(1):8–16. Price FW Jr, Price MO. To intervene or not to intervene: that is the question. Ophthalmology 2015;122(1):6–7. Suh LH, Dawson DG, Mutapcic L, et al. Histopathologic examination of failed grafts in descemet’s stripping with automated endothelial keratoplasty. Ophthalmology 2009;116(4): 603–608. Weller JM, Zenkel M, Schlo¨tzer-Schrehardt U, Bachmann BO, Tourtas T, Kruse FE. Extracellular matrix alterations in late-onset Fuchs’ corneal dystrophy. Invest Ophthalmol Vis Sci 2014;55(6):3700–3708. Oster SF, Ebrahimi KB, Eberhart CG, Schein OD, Stark WJ, Jun AS. A clinicopathologic series of primary graft failure after Descemet’s stripping and automated endothelial keratoplasty. Ophthalmology 2009;116(4):609–614. Shulman J, Kropinak M, Ritterband DC, et al. Failed descemet-stripping automated endothelial keratoplasty grafts: a clinicopathologic analysis. Am J Ophthalmol 2009; 148(5):752–759. Zhang Q, Randleman JB, Stulting RD, et al. Clinicopathologic findings in failed descemet stripping automated endothelial keratoplasty. Arch Ophthalmol 2010;128(8): 973–980. Schlo¨tzer-Schrehardt U, Bachmann BO, Tourtas T, et al. Reproducibility of graft preparations in Descemet’s membrane endothelial keratoplasty. Ophthalmology 2013;120(9): 1769–1777.
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Biosketch Julia M. Weller graduated from Medical School of the University of Erlangen-Nuremberg, Germany in 2010. She is a member of the Department of Ophthalmology at the University of Erlangen-Nuremberg, Germany. Her research interests include corneal endothelial transplantation and the pathophysiology of Fuchs’ endothelial corneal dystrophy.
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SUPPLEMENTAL FIGURE. Correlation between bestcorrected visual acuity (BCVA) preoperatively and 1 month after Descemet membrane endothelial keratoplasty (DMEK) in the general cohort of Descemet membrane endothelial keratoplasties of the Department of Ophthalmology, University Erlangen-Nuremberg, Germany (n [ 216, Spearman correlation coefficient 1 month: r 0.281, P < .001, 12 months: r 0.274, P [ .005).
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