Ultrathin Descemet Stripping Automated Endothelial Keratoplasty (UT-DSAEK) versus Descemet Membrane Endothelial Keratoplasty (DMEK) - A Systematic Review & Meta-Analysis

Abstract

Background/Objectives:

Endothelial keratoplasty (EK) is a commonly performed transplant procedure used in the treatment of corneal endothelial dysfunction. The aim of this systematic review and meta-analysis is to evaluate the differences in visual acuity outcomes, endothelial cell density (ECD) and complications between two forms of EK, ultrathin descemet stripping automated endothelial keratoplasty (UT-DSAEK) and descemet membrane endothelial keratoplasty (DMEK).

Methods:

A comprehensive literature search was conducted to identify studies reporting comparative results of UT-DSAEK versus DMEK. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was used for search strategy. Of 141 titles, 7 studies met the inclusion criteria; best corrected visual acuity (BCVA) (LogMAR), ECD (cells/mm²), and complications were compared, with all statistical analysis performed using Review Manager.

Results:

A total of 362 eyes were included for analysis. DMEK resulted in significantly better BCVA at 3 months (0.13 vs 0.23, p = 0.003) and 1 year post-op (0.10 vs 0.19, p = 0.0005). UT-DSAEK resulted in significantly lower total complications (25.2% vs 57.3%, p = 0.0001) and rates of re-bubbling (11.0% vs 33.7%, p = 0.004). No differences were found in ECD between the two procedures (1,673.8 vs 1,705.3, p = 0.77).

Conclusions:

DMEK results in superior visual acuity rates with quicker recovery. However, UT-DSAEK has a more favourable complication profile, particularly regarding lower rates of re-bubbling. Both are valuable options in the treatment of corneal endothelial disease and choice of procedure may depend on surgical expertise.

Introduction

Corneal transplantation is the most performed type of allogeneic transplantation worldwide with approximately 185,000 keratoplasties being undertaken place annually (1). Since the first transplantation in 1905, the procedure has seen advances from full thickness transplantation, known as penetrating keratoplasty (PK), to the selective replacement of damaged layers, known as lamellar keratoplasty. Most progress has been seen in endothelial keratoplasty (EK), a procedure in which the diseased corneal endothelium is replaced. The corneal endothelium plays an essential role in maintaining corneal hydration and clarity through the endothelial Na+/K + ATPase pump and tight junctions between endothelial cells that tightly regulate the transport of fluid into the stroma (2). The average adult cornea has an endothelial cell density (ECD) of approximately 2,500–3,000 cells/mm², with a reduction of approximately 0.6% per year (3). When endothelial cell density falls below 500–800 cells/mm², decompensation may occur leading to corneal edema and necessitating corneal transplantation.

EK is the gold standard in treating corneal endothelial disease as it offers quicker recovery, improved visual acuity and fewer complications compared to PK. It is most commonly indicated for Fuchs’ endothelial dystrophy (47.1%), followed by pseudophakic bullous keratopathy (17.5%) (4). Within the scope of EK, there has been a shift towards the use of thinner grafts. Descemet’s stripping automated endothelial keratoplasty (DSAEK) involves the transplantation of the posterior stroma, Descemet membrane and the endothelium. By comparison, descemet membrane endothelial keratoplasty (DMEK) involves the removal and transplantation of just Descemet’s membrane and the endothelium. DMEK has been shown to further improve visual acuity and reduce rates of graft rejection (5). However, DMEK is a technically challenging procedure with higher rates of operative complications due to the thinness and fragility of the graft (6).

Ultrathin-DSAEK (UT-DSAEK) is a relatively new form of EK that may bridge the gap between DSAEK’s less challenging use and DMEK’s superior results. UT-DSAEK is commonly agreed to comprise donor grafts of approximately < 110 − 100µm thick, smaller than the traditional DSAEK’s 150µm and larger than DMEK’s average 10–15µm thickness (7, 8). This is achieved through a single or double microkeratome pass, the first pass debulking the donor tissue and the second pass refining it to the optimal thickness (9). UT-DSAEK was shown to have superior visual acuity outcomes compared to the traditional DSAEK procedure in a large case series (10) and randomised controlled trial (11) without increasing the risk of graft detachment.

To date, there have been a small number of randomized controlled trials comparing UT-DSAEK and DMEK but no meta-analyses performed on the topic. The aim of this study is to compare best corrected visual acuity (BCVA) outcomes, ECD and complication rates between the two procedures.

Methods

Results

Literature Search

The initial literature search identified a total of 141 studies. After removal of duplicates, the articles were screened for the inclusion and exclusion criteria; 68 unique studies were evaluated and 27 full texts were assessed for eligibility. Seven studies with 362 eyes (322 patients) were included in this review (14–20). Rose-Nussbaumer et al (2021) is a 2 year follow-up of the same cohort as Chamberlain et al (2019) and this has been included for analysis as one paper, the DETECT (Descemet Endothelial Thickness Comparison Trial) study, to avoid duplication. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flowchart can be in the appendix.

Discussion

DMEK results in superior visual acuity outcomes compared to UT-DSAEK. This difference is most pronounced in the initial 3 months post-operatively, highlighting its faster visual rehabilitation, but it remains significantly better after 1 year follow-up. This is likely due to the improved restoration of anatomy in the DMEK procedure because of the use of a thinner graft with no lamellae and lack of stroma-to-stroma graft interface. Thinner grafts have been shown to induce fewer higher order aberrations and less hyperopic shift which may explain DMEK’s visual acuity superiority of UT-DSAEK (21–23). DMEK procedures also utilise smaller incisions, 2.2-3.5mm for DMEK versus 3.5-4.5mm for UT-DSAEK, which results in less surgically induced astigmatism (24). Both Mencucci et al. and Torras-Sanvicens et al. performed retrospective fellow eye comparisons of patients who underwent UT-DSAEK in one eye and DMEK in the other (16, 20). Although, they found similar BCVA at one year follow-up, DMEK performed better in terms of contrast sensitivity, posterior corneal aberrations and overall patient satisfaction.

Some discordance in visual acuity outcomes exists between our randomised controlled trials (8, 14, 15, 17). All three studies used strict eligibility criteria, only analysing patients with endothelial disease, primarily Fuchs’ endothelial dystrophy, in the absence of other vision-limiting pathologies. Dunker et al. found no significant differences in visual acuity between the two procedures as early as 3 months post-operatively and up to 1 year (14). They assessed outcomes in pre-operatively pseudophakic eyes to isolate the effect of keratoplasty alone on visual outcome. Although this doesn’t reflect the heterogeneity of the patient population attending for endothelial keratoplasty, it does suggest that the outcomes analysed are primarily attributable to the procedure alone. They did however report that a higher percentage of patients attained 0.1 LogMAR in the DMEK arm (66% of 29 eyes) compared to the UT-DSAEK arm (33% of 25 eyes). The DETECT and Matsou studies showed superior visual acuity in the DMEK group. 70% of patients in the DETECT cohort had a triple procedure. This, however, was done in equal proportion between both procedures, 68% in the UT-DSAEK group and 72% in the DMEK group. Although this may affect pre-operative BCVA, all patients analysed across all studies were pseudophakic at the end of their keratoplasty allowing comparable analysis of post-operative BCVA at one year.

The variability in outcomes between the studies may also relate to an inherent limitation in UT-DSAEK that is the lack of graft regularity. Graft regularity is an important parameter in the quality of an UT-DSAEK graft as and remains difficult to standardize, even with eye bank-prepared tissues (21). Despite this, the DETECT study and Matsou et al. found no difference in patient-reported functional vision as assessed by vision related quality of life (15, 25). This is in line with Matsou and Dunker’s findings of no significant difference in mean spherical equivalent, posterior and anterior corneal astigmatism between the two cohorts at any time point (14, 15).

ECD is a major factor in long-term graft survival (26). The Cornea Preservation Time Study evaluated factors influencing graft success and they found higher success in cases of Fuchs’ endothelial dystrophy, cases without any intra-operative complications and in which the donor did not have diabetes (27). In our analysis, we found ECD was comparable between the procedures. This is in line with multiple RCTs looking at ECD between DMEK and traditional DSAEK which have found no significant difference in the early post-operative period (6, 28, 29).

The rate of total complications is markedly higher after DMEK than after UT-DSAEK. The most reported complication in each cohort was graft detachment requiring re-bubbling (anterior chamber tamponade re-injections). This is a significant concern following DMEK (18). Romano et al. reported that re-bubbling was also higher in eyes undergoing triple procedure, occurring in 3/11 eyes having UT-DSAEK-triple and 8/15 undergoing DMEK-triple. However, contradictory results in other case series have shown that combining cataract procedures with DSAEK (30) or DMEK (31) has no impact on rates of detachment. The reported rates of re-bubbling following DMEK vary widely, ranging from 2–82% but on average are considered to occur in just under one-third of patients (32, 33). Repeated re-bubblings are associated with endothelial cell loss, raised intraocular pressure and graft rejections (6). Re-bubbling also poses additional logistic issues. It may have to be performed in theatre where access can often be an issue and may take precedence over other elective ophthalmic procedures. However, DMEK re-bubbling may be more frequently performed in clinic, compared to UT-DSAEK which often requires management in theatre owing to the higher pressure required for successful tamponade. Graft detachment rates may be reduced with the use of pre-stamped DMEK tissue (34). Additionally, studies have shown that SF6 gas anterior chamber tamponade may further reduce the risk of detachment to approximately 12% by facilitating adhesion at the graft-host interface (35–37). The DETECT study and Dunker et al. noted that the use of SF6 made no statistical difference to rates of re-bubbling, although they weren’t powered to specifically analyse this (8, 14, 17). Studies have also shown that the use of SF6 tamponade does not affect long-term BCVA or ECD (35–37).

Raised IOP was the second most reported complication in each cohort. It was not clearly stated what percentage of patients went on to develop secondary glaucoma. This raised IOP is likely a result of post-operative steroid use but may also develop from air bubble-related pupillary block (38). Prophylactic peripheral iridotomy may be performed pre- or intra-operatively to reduce the risk of pupillary block in either procedure (39).

Rates of graft failure (2 in DMEK & 1 in UT-DSAEK) and rejection were very low (1 in DMEK & 2 in UT-DSAEK). However, longer follow-up is required to comment on the risk of risk of allograft rejection and graft survival. As less tissue is transplanted in DMEK, there should be a reduced risk of allograft rejection and less reliance on topical steroids. A multi-centre study of 431 patients who underwent DMEK found a 3.7% (16 eyes) graft rejection rate (40). This is significantly lower than the rejection rates commonly reported following traditional DSAEK (9%) (41). UT-DSAEK may have lower rates of rejection compared to its predecessor, DSAEK, with its thinner graft and a large prospective series has shown similar rates of immunologic rejection to DMEK (10).

An important consideration is the use of eye bank versus surgeon prepared endothelial grafts. Romano et al. looked at DMEK graft preparation and found significantly higher adhesion and lower re-bubbling rates with surgeon prepared DMEK grafts compared to eye bank prepared tissue (18). Similar results were seen in a study examining re-bubbling rates in DSAEK procedures, with fewer detachments occurring in the surgeon prepared group (42). The use of surgeon or local technician prepared endothelial grafts, both DMEK and traditional DSAEK, have also been shown to significantly reduce surgical expenses in Canada and the United Kingdom (42, 43). These studies did not specifically analyse surgeon prepared UT-DSAEK grafts. However, both single and double-pass microkeratome techniques for performing have been well described in the literature with reproducible results (44–46). Techniques to improve graft preparation consistency include controlling artificial anterior chamber pressure and drying the corneal surface, described by Romano et al, and stromal swelling with balanced salt solution prior to microkeratome pass, detailed by Farbman et al. Single and double pass techniques for UT-DSAEK graft preparation have been shown to have comparable thickness, ECD and BCVA (47).

In 2015, according to the Eye Bank Association of America, DMEK comprised 15% of all EK procedures in the United States, whereas DSAEK accounted for over 50%. In 2021, their usage was almost equal (DMEK: 14,128 vs DSAEK: 15,935) (48). DMEK’s widespread adoption may have initially been limited by its highly technical nature, at every stage from donor tissue preparation to placement to post-operative graft attachment. Owing to the fragility of the tissue, graft folds occur in approximately 1.9% which may cause optical aberrations (40). Many studies have shown a steep learning curve for DMEK with an inverse relationship between surgeon experience and rates of graft detachment (49–51). Dapena et al examined the outcomes in a series of consecutive cases performed by a single surgeon and found re-bubbling was required in 20% of the first 45 cases, 13.3% in the middle 45 cases and 4.4% in the final 45 cases (49). DMEK is also a more challenging procedure in patients with complex anatomy, such as a very shallow or deep anterior chamber or a history of prior intra-ocular surgery or trauma (52). Visual outcomes and endothelial cell loss following DMEK remain stable however once the surgeon has completed a minimum of 25 cases (50, 51).

Conclusion

In summary, visual outcomes were superior following DMEK with quicker recovery and better overall visual acuity. Conversely, UT-DSAEK is associated with fewer complications, particularly graft detachments requiring re-bubbling. Both procedures remain valuable options for a cornea specialist with prudent decision making given to the right operation for the right patient. Further large multicentre randomised controlled trials are required to further clarify differences between the two procedures, particularly in terms of endothelial cell loss, graft rejection and overall graft survival.

Declarations

Funding: This study received no external funding

Conflicts of Interest: The authors declare no conflicts of interest

Type of research: Meta-Analysis and Systematic Review

Acknowledgments

This study received no external funding. The authors declare no conflicts of interest.

References

1. Gain P, Jullienne R, He Z, Aldossary M, Acquart S, Cognasse F, et al. Global Survey of Corneal Transplantation and Eye Banking. JAMA Ophthalmol. 2016;134(2):167–73.
2. Yee RW, Geroski DH, Matsuda M, Champeau EJ, Meyer LA, Edelhauser HF. Correlation of corneal endothelial pump site density, barrier function, and morphology in wound repair. Invest Ophthalmol Vis Sci. 1985;26(9):1191–201.
3. Edelhauser HF. The balance between corneal transparency and edema: the Proctor Lecture. Invest Ophthalmol Vis Sci. 2006;47(5):1754–67.
4. America EBAo. 2014 Eye Banking Statistical Report. Washington, DC: Eye Bank Association of America; 2015.
5. Deng SX, Lee WB, Hammersmith KM, Kuo AN, Li JY, Shen JF, et al. Descemet Membrane Endothelial Keratoplasty: Safety and Outcomes: A Report by the American Academy of Ophthalmology. Ophthalmology. 2018;125(2):295–310.
6. Singh A, Zarei-Ghanavati M, Avadhanam V, Liu C. Systematic Review and Meta-Analysis of Clinical Outcomes of Descemet Membrane Endothelial Keratoplasty Versus Descemet Stripping Endothelial Keratoplasty/Descemet Stripping Automated Endothelial Keratoplasty. Cornea. 2017;36(11):1437–43.
7. Chamberlain W, Austin A, Terry M, Jeng BH, Rose-Nussbaumer J. Survey of Experts on Current Endothelial Keratoplasty Techniques. J Clin Exp Ophthalmol. 2016;7(5).
8. Chamberlain W, Lin CC, Austin A, Schubach N, Clover J, McLeod SD, et al. Descemet Endothelial Thickness Comparison Trial: A Randomized Trial Comparing Ultrathin Descemet Stripping Automated Endothelial Keratoplasty with Descemet Membrane Endothelial Keratoplasty. Ophthalmology. 2019;126(1):19–26.
9. Busin M, Albe E. Does thickness matter: ultrathin Descemet stripping automated endothelial keratoplasty. Curr Opin Ophthalmol. 2014;25(4):312–8.
10. Busin M, Madi S, Santorum P, Scorcia V, Beltz J. Ultrathin descemet's stripping automated endothelial keratoplasty with the microkeratome double-pass technique: two-year outcomes. Ophthalmology. 2013;120(6):1186–94.
11. Dickman MM, Kruit PJ, Remeijer L, van Rooij J, Van der Lelij A, Wijdh RH, et al. A Randomized Multicenter Clinical Trial of Ultrathin Descemet Stripping Automated Endothelial Keratoplasty (DSAEK) versus DSAEK. Ophthalmology. 2016;123(11):2276–84.
12. Wells GA SB, O’Connell D et al. The Newcastle-Ottawa Scale (NOS) for assessing the quality of nonrandomised studies in meta-analyses. Ottawa Hospital Research Institute. 2014.
13. Higgins JP, Thompson SG. Quantifying heterogeneity in a meta-analysis. Stat Med. 2002;21(11):1539–58.
14. Dunker SL, Dickman MM, Wisse RPL, Nobacht S, Wijdh RHJ, Bartels MC, et al. Descemet Membrane Endothelial Keratoplasty versus Ultrathin Descemet Stripping Automated Endothelial Keratoplasty: A Multicenter Randomized Controlled Clinical Trial. Ophthalmology. 2020;127(9):1152–9.
15. Matsou A, Pujari R, Sarwar H, Rana M, Myerscough J, Thomson SM, et al. Microthin Descemet Stripping Automated Endothelial Keratoplasty Versus Descemet Membrane Endothelial Keratoplasty: A Randomized Clinical Trial. Cornea. 2021;40(9):1117–25.
16. Mencucci R, Favuzza E, Marziali E, Cennamo M, Mazzotta C, Lucenteforte E, et al. Ultrathin Descemet stripping automated endothelial keratoplasty versus Descemet membrane endothelial keratoplasty: a fellow-eye comparison. Eye Vis (Lond). 2020;7:25.
17. Rose-Nussbaumer J, Lin CC, Austin A, Liu Z, Clover J, McLeod SD, et al. Descemet Endothelial Thickness Comparison Trial: Two-Year Results from a Randomized Trial Comparing Ultrathin Descemet Stripping Automated Endothelial Keratoplasty with Descemet Membrane Endothelial Keratoplasty. Ophthalmology. 2021;128(8):1238–40.
18. Romano V, Pagano L, Gadhvi KA, Coco G, Titley M, Fenech MT, et al. Clinical outcomes of pre-loaded ultra-thin DSAEK and pre-loaded DMEK. BMJ Open Ophthalmol. 2020;5(1):e000546.
19. Tourabaly M, Chetrit Y, Provost J, Georgeon C, Kallel S, Temstet C, et al. Influence of graft thickness and regularity on vision recovery after endothelial keratoplasty. Br J Ophthalmol. 2020;104(9):1317–23.
20. Torras-Sanvicens J, Blanco-Dominguez I, Sanchez-Gonzalez JM, Rachwani-Anil R, Spencer JF, Sabater-Cruz N, et al. Visual Quality and Subjective Satisfaction in Ultrathin Descemet Stripping Automated Endothelial Keratoplasty (UT-DSAEK) versus Descemet Membrane Endothelial Keratoplasty (DMEK): A Fellow-Eye Comparison. J Clin Med. 2021;10(3).
21. Dickman MM, Cheng YY, Berendschot TT, van den Biggelaar FJ, Nuijts RM. Effects of graft thickness and asymmetry on visual gain and aberrations after descemet stripping automated endothelial keratoplasty. JAMA Ophthalmol. 2013;131(6):737–44.
22. Hamzaoglu EC, Straiko MD, Mayko ZM, Sales CS, Terry MA. The First 100 Eyes of Standardized Descemet Stripping Automated Endothelial Keratoplasty versus Standardized Descemet Membrane Endothelial Keratoplasty. Ophthalmology. 2015;122(11):2193–9.
23. Green M, Wilkins MR. Comparison of Early Surgical Experience and Visual Outcomes of DSAEK and DMEK. Cornea. 2015;34(11):1341–4.
24. Yokogawa H, Sanchez PJ, Mayko ZM, Straiko MD, Terry MA. Corneal Astigmatism Stability in Descemet Membrane Endothelial Keratoplasty for Fuchs Corneal Dystrophy. Cornea. 2016;35(7):932–7.
25. Ang MJ, Chamberlain W, Lin CC, Pickel J, Austin A, Rose-Nussbaumer J. Effect of Unilateral Endothelial Keratoplasty on Vision-Related Quality-of-Life Outcomes in the Descemet Endothelial Thickness Comparison Trial (DETECT): A Secondary Analysis of a Randomized Clinical Trial. JAMA Ophthalmol. 2019;137(7):747–54.
26. Patel SV, Lass JH, Benetz BA, Szczotka-Flynn LB, Cohen NJ, Ayala AR, et al. Postoperative Endothelial Cell Density Is Associated with Late Endothelial Graft Failure after Descemet Stripping Automated Endothelial Keratoplasty. Ophthalmology. 2019;126(8):1076–83.
27. Terry MA, Aldave AJ, Szczotka-Flynn LB, Liang W, Ayala AR, Maguire MG, et al. Donor, Recipient, and Operative Factors Associated with Graft Success in the Cornea Preservation Time Study. Ophthalmology. 2018;125(11):1700–9.
28. Droutsas K, Lazaridis A, Papaconstantinou D, Brouzas D, Moschos MM, Schulze S, et al. Visual Outcomes After Descemet Membrane Endothelial Keratoplasty Versus Descemet Stripping Automated Endothelial Keratoplasty-Comparison of Specific Matched Pairs. Cornea. 2016;35(6):765–71.
29. Heinzelmann S, Bohringer D, Eberwein P, Reinhard T, Maier P. Outcomes of Descemet membrane endothelial keratoplasty, Descemet stripping automated endothelial keratoplasty and penetrating keratoplasty from a single centre study. Graefes Arch Clin Exp Ophthalmol. 2016;254(3):515–22.
30. Terry MA, Shamie N, Chen ES, Phillips PM, Shah AK, Hoar KL, et al. Endothelial keratoplasty for Fuchs' dystrophy with cataract: complications and clinical results with the new triple procedure. Ophthalmology. 2009;116(4):631–9.
31. Godin MR, Boehlke CS, Kim T, Gupta PK. Influence of Lens Status on Outcomes of Descemet Membrane Endothelial Keratoplasty. Cornea. 2019;38(4):409–12.
32. 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):1082–90 e2.
33. Phillips PM, Phillips LJ, Muthappan V, Maloney CM, Carver CN. Experienced DSAEK Surgeon's Transition to DMEK: Outcomes Comparing the Last 100 DSAEK Surgeries With the First 100 DMEK Surgeries Exclusively Using Previously Published Techniques. Cornea. 2017;36(3):275–9.
34. Veldman PB, Dye PK, Holiman JD, Mayko ZM, Sales CS, Straiko MD, et al. The S-stamp in Descemet Membrane Endothelial Keratoplasty Safely Eliminates Upside-down Graft Implantation. Ophthalmology. 2016;123(1):161–4.
35. Guell JL, Morral M, Gris O, Elies D, Manero F. Comparison of Sulfur Hexafluoride 20% versus Air Tamponade in Descemet Membrane Endothelial Keratoplasty. Ophthalmology. 2015;122(9):1757–64.
36. Siebelmann S, Lopez Ramos S, Scholz P, Matthaei M, Schrittenlocher S, Heindl LM, et al. Graft Detachment Pattern After Descemet Membrane Endothelial Keratoplasty Comparing Air Versus 20% SF6 Tamponade. Cornea. 2018;37(7):834–9.
37. von Marchtaler PV, Weller JM, Kruse FE, Tourtas T. Air Versus Sulfur Hexafluoride Gas Tamponade in Descemet Membrane Endothelial Keratoplasty: A Fellow Eye Comparison. Cornea. 2018;37(1):15–9.
38. Rock D, Bartz-Schmidt KU, Rock T, Yoeruek E. Air Bubble-Induced High Intraocular Pressure After Descemet Membrane Endothelial Keratoplasty. Cornea. 2016;35(8):1035–9.
39. Ang M, Sng CCA. Descemet membrane endothelial keratoplasty and glaucoma. Curr Opin Ophthalmol. 2018;29(2):178–84.
40. Monnereau C, Quilendrino R, Dapena I, Liarakos VS, Alfonso JF, Arnalich-Montiel F, et al. Multicenter study of descemet membrane endothelial keratoplasty: First case series of 18 surgeons. JAMA Ophthalmology. 2014;132(10):1192–8.
41. Anshu A, Price MO, Price FW, Jr. Risk of corneal transplant rejection significantly reduced with Descemet's membrane endothelial keratoplasty. Ophthalmology. 2012;119(3):536–40.
42. Pagano L, Gadhvi KA, Coco G, Fenech M, Titley M, Levis HJ, et al. Rebubbling rate in preloaded versus surgeon prepared DSAEK. Eur J Ophthalmol. 2021:11206721211014380.
43. Tong CM, Ellis D, Kissick B, Kurji K, Mah DY, Climenhaga DB. Cost-effectiveness of locally prepared Descemet membrane endothelial keratoplasty grafts in Edmonton. Can J Ophthalmol. 2022.
44. Cheung AY, Hou JH, Bedard P, Grimes V, Buckman N, Eslani M, et al. Technique for Preparing Ultrathin and Nanothin Descemet Stripping Automated Endothelial Keratoplasty Tissue. Cornea. 2018;37(5):661–6.
45. Farbman NH, J YL, Ling J, Conwell C, Ramirez T. A Simple 60-Second Swelling Technique for More Consistent Ultrathin DSAEK Graft Preparation. Cornea. 2019;38(10):1209–14.
46. Romano V, Steger B, Myneni J, Batterbury M, Willoughby CE, Kaye SB. Preparation of ultrathin grafts for Descemet-stripping endothelial keratoplasty with a single microkeratome pass. J Cataract Refract Surg. 2017;43(1):12–5.
47. Sharma N, Hussain AY, Nagpal R, Rathi A, Maharana PK, Sinha R, et al. Microkeratome-assisted ultrathin Descemet's stripping automated endothelial keratoplasty: A randomized trial comparing single-pass versus double-pass technique. Indian J Ophthalmol. 2019;67(8):1289–94.
48. 2021 Eye Banking Statistical Report [press release]. Washington, DC: Eye Bank Association of America2021.
49. Dapena I, Ham L, Droutsas K, van Dijk K, Moutsouris K, Melles GR. Learning Curve in Descemet's Membrane Endothelial Keratoplasty: First Series of 135 Consecutive Cases. Ophthalmology. 2011;118(11):2147–54.
50. Oellerich S, Baydoun L, Peraza-Nieves J, Ilyas A, Frank L, Binder PS, et al. Multicenter Study of 6-Month Clinical Outcomes After Descemet Membrane Endothelial Keratoplasty. Cornea. 2017;36(12):1467–76.
51. Schrittenlocher S, Schaub F, Hos D, Siebelmann S, Cursiefen C, Bachmann B. Evolution of Consecutive Descemet Membrane Endothelial Keratoplasty Outcomes Throughout a 5-Year Period Performed by Two Experienced Surgeons. Am J Ophthalmol. 2018;190:171–8.
52. Bachmann B, Schrittenlocher S, Matthaei M, Siebelmann S, Cursiefen C. [Descemet membrane endothelial keratoplasty in complex eyes]. Ophthalmologe. 2019;116(3):228–35.

Tables

Table I. Study Characteristics & Patient Demographics

 Table II. Pre-Operative and Operative Data