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Title: "Endothelium-Out" and "Endothelium-In" descemet membrane endothelial keratoplasty (DMEK) graft insertion techniques: a systematic review with meta-analysis
Authors: Ong, Hon Shing
Htoon, Hla M.
Ang, Marcus
Mehta, Jodhbir Singh
Keywords: Science::Medicine
Issue Date: 2022
Source: Ong, H. S., Htoon, H. M., Ang, M. & Mehta, J. S. (2022). "Endothelium-Out" and "Endothelium-In" descemet membrane endothelial keratoplasty (DMEK) graft insertion techniques: a systematic review with meta-analysis. Frontiers in Medicine, 9, 868533-.
Journal: Frontiers in Medicine 
Abstract: Background: We evaluated the visual outcomes and complications of “endothelium-out” and “endothelium-in” Descemet membrane endothelial keratoplasty (DMEK) graft insertion techniques. Materials and Methods: Electronic searches were conducted in CENTRAL, Cochrane databases, PubMed, EMBASE, Study designs included clinical trials, comparative observational studies, and large case series (≥25 eyes). PRISMA guidelines were used for abstracting data and synthesis. Random-effects models were employed for meta-analyses. Results: 21,323 eyes (95 studies) were included. Eighty-six studies reported on “endothelium-out” techniques; eight studies reported on “endothelium-in” techniques. One study compared “endothelium-out” to “endothelium-in” techniques. Eighteen “endothelium-out” studies reported that 42.5–85% of eyes achieved best-corrected visual acuity (BCVA) ≥20/25 at 6 months; pooled proportion of eyes achieving BCVA ≥20/25 at 6 months was 58.7% (95% CI 49.4–67.7%,15 studies). Three “endothelium-in” studies reported that 44.7–87.5% of eyes achieved BCVA of ≥20/25 at 6 months; pooled proportion of eyes achieving BCVA ≥20/25 at 6 months was 62.4% (95% CI 33.9–86.9%). Pooled mean endothelial cell loss was lower in the “endothelium-in” studies (28.1 ± 1.3%, 7 studies) compared to “endothelium-out” studies (36.3 ± 6.9%,10 studies) at 6 months (p = 0.018). Graft re-bubbling rates were higher in the “endothelium-out” studies (26.2%, 95% CI 21.9–30.9%, 74 studies) compared to “endothelium-in” studies (16.5%, 95% CI 8.5–26.4%, 6 studies), although statistical significance was not reached (p = 0.440). Primary graft failure rates were comparable between the two groups (p = 0.552). Quality of evidence was considered low and significant heterogeneity existed amongst the studies. Conclusion: Reported rates of endothelial cell loss were lower in “endothelium-in” DMEK studies at 6 months compared to “endothelium-out” studies. Outcomes of “endothelium-in” techniques were otherwise comparable to those reported in “endothelium-out” studies. Given the technical challenges encountered in “endothelium-out” procedures, surgeons may consider “endothelium-in” techniques designed for easier intra-operative DMEK graft unfolding. “Endothelium-in” studies evaluating outcomes at longer time points are required before conclusive comparisons between the two techniques can be drawn.
ISSN: 2296-858X
DOI: 10.3389/fmed.2022.868533
Schools: School of Materials Science and Engineering 
Organisations: Singapore National Eye Centre 
Singapore Eye Research Institute 
Duke-NUS Medical School 
Rights: Copyright © 2022 Ong, Htoon, Ang and Mehta. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Fulltext Permission: open
Fulltext Availability: With Fulltext
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