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Outcomes of first cases of DMEK at a Canadian university hospital centre

      Descemet membrane endothelial keratoplasty (DMEK) provides better visual outcomes and lower rejection rates than Descemet stripping automated endothelial keratoplasty (DSAEK).
      • Hamzaoglu EC
      • Straiko MD
      • Mayko ZM
      • et al.
      The first 100 eyes of standardized Descemet stripping automated endothelial keratoplasty versus standardized Descemet membrane endothelial keratoplasty.
      ,
      • Anshu A
      • Price MO
      • Price Jr, FW
      Risk of corneal transplant rejection significantly reduced with Descemet's membrane endothelial keratoplasty.
      However, steep learning curves, higher rebubbling rates, and failure risks have been noted.
      • Terry MA.
      Endothelial keratoplasty: why aren't we all doing Descemet membrane endothelial keratoplasty?.
      • Price MO
      • Giebel AW
      • Fairchild KM
      • et al.
      Descemet's membrane endothelial keratoplasty: prospective multicenter study of visual and refractive outcomes and endothelial survival.
      • Ham L
      • Dapena I
      • van Luijk C
      • et al.
      Descemet membrane endothelial keratoplasty (DMEK) for Fuchs endothelial dystrophy: review of the first 50 consecutive cases.
      • Dapena I
      • Ham L
      • Droutsas K
      • et al.
      Learning curve in Descemet's membrane endothelial keratoplasty: first series of 135 consecutive cases.
      This study aimed to report and analyze the outcomes of the first DMEK cases in our university-based centre.
      Files of all patients who underwent DMEK between March 2016 and October 2018 were retrospectively reviewed at the Centre Hospitalier de l'Université de Montréal (CHUM). DMEKs were performed by five surgeons and included all their first cases. Surgical technique varied between each surgeon. In general, tissues were prestripped and prestamped using the S-stamp technique. Grafts were partially trephined using a Hanna punch and peeled using the stereotactic intracerebral hemorrhage underwater blood aspiration (SCUBA) technique. After staining donor tissues in trypan blue, descemetorhexis was performed 0.5 mm larger than the graft diameter. Grafts were loaded into a modified Jones tube and injected into the anterior chamber (AC). Once adequately positioned, 20% SF6 gas was injected in the AC. Peripheral iridotomies were performed occasionally. Management of AC gas slightly differed between surgeons. The pupil was dilated, and patients were instructed to lie supine. Prior to discharge, slit-lamp examination was performed to ensure no pupillary block. This study was conducted in compliance with the Declaration of Helsinki, and approval was obtained from the CHUM Research Ethics Board.
      Eighty-five eyes from 73 patients were included in this study. Six patients had a second DMEK, for a total of 91 procedures. Mean follow-up time was 10.6 ± 7.1 months. Eighty eyes (94%) had a diagnosis of Fuchs’ endothelial corneal dystrophy, and 5 eyes (6%) had pseudophakic bullous keratopathy. Thirty-one patients (36%) had at least one ocular comorbidity, most of them affecting the posterior pole. Twelve eyes (14%) had complex anterior segments, from which 6 had previous DMEK, 4 had DSAEK, 1 had Descemet stripping only, 1 had penetrating keratoplasty, and 2 had pars plana vitrectomy. No patient had had glaucoma surgery prior to DMEK. Mean graft diameter was 8.0 ± 0.3 mm. Five surgeries were combined with phacoemulsification and intraocular lens implantation. Twenty-seven surgeries (30%) had an intraoperative complication, and 14 (15%) grafts had suboptimal preparation (Table 1). Visual outcomes (presented in Table 2) are consistent with current studies.
      • Deng SX
      • Lee WB
      • Hammersmith KM
      • et al.
      Descemet membrane endothelial keratoplasty: safety and outcomes. A report by the American Academy of Ophthalmology.
      Mean donor endothelial cell count was 2764 ± 256 cells/mm2 preoperatively, 1539 ± 555 cells/mm2 at 6 months, and 1391 ± 504 cells/mm2 at 12 months. Median endothelial cell loss was 45% at 6 months and 50% at 12 months. Central corneal thickness decreased by 122 ± 43 μm (p < 0.001) at 6 months and by 114 ± 46 μm (p < 0.001) at 12 months. Postoperative complications are presented in Table 1. The rebubble rate in our cohort is below rates reported in the literature.
      • Hamzaoglu EC
      • Straiko MD
      • Mayko ZM
      • et al.
      The first 100 eyes of standardized Descemet stripping automated endothelial keratoplasty versus standardized Descemet membrane endothelial keratoplasty.
      ,
      • Price MO
      • Giebel AW
      • Fairchild KM
      • et al.
      Descemet's membrane endothelial keratoplasty: prospective multicenter study of visual and refractive outcomes and endothelial survival.
      ,
      • Showail M
      • Obthani MA
      • Sorkin N
      • et al.
      Outcomes of the first 250 eyes of Descemet membrane endothelial keratoplasty: Canadian centre experience.
      Mean rebubbling time was 10 ± 5 days postoperatively. Rebubbling was performed if the graft detachment involved more than a third of the graft, caused visual axis edema, or progressed during follow-up. Primary graft failure (PGF) occurred in 21% of eyes, a rate slightly above numbers found in current studies (8%–20%).
      • Price MO
      • Giebel AW
      • Fairchild KM
      • et al.
      Descemet's membrane endothelial keratoplasty: prospective multicenter study of visual and refractive outcomes and endothelial survival.
      ,
      • Ham L
      • Dapena I
      • van Luijk C
      • et al.
      Descemet membrane endothelial keratoplasty (DMEK) for Fuchs endothelial dystrophy: review of the first 50 consecutive cases.
      Complicated surgery (p = 0.008) and suboptimal tissue preparation (p = 0.027) were significantly associated with rebubbling and/or PGF. The surgeon who performed the most DMEKs (n = 33) had a PGF rate of 12%, whereas the surgeon with the least cases (n = 5) had a rate of 40%. This indicates that the learning curve may influence PGF outcomes in our cohort.
      Table 1Complications and regraft rate
      Intraoperative Complicationsn (%)
      Difficult graft unfolding5 (6)
      Displacement of the graft requiring same-day operative repositioning4 (4)
      Ejection of the graft3 (3)
      Pupillary block3 (3)
      Intracameral fibrin2 (2)
      Hyphema1 (1)
      Iris extrusion through the operative wound1 (1)
      Intraoperative graft contamination1 (1)
      Suboptimal tissue preparation
       Important endothelial staining (preoperative endothelial damage)6 (7)
       Presence of tears5 (6)
       S-stamp needing to be re-marked3 (3)
       Decentred trephination2 (2)
       Prestripping incomplete2 (2)
       Friable graft/peripheral tears2 (2)
      Postoperative Complicationsn (%)
      Partial graft detachment40 (44)
      Primary graft failure19 (21)
      Rebubble14 (15)
      Cystoid macular edema9 (10)
      Ocular hypertension9 (10)
      Postoperative pupillary block8 (9)
      Full graft detachment (free floating)3 (3)
      Epiretinal membrane3 (3)
      Surgical mydriasis1 (1)
      Rejection0
      Regraft20 (22)
       DSAEK11 (12)
       DMEK6 (7)
       Penetrating keratoplasty3 (3)
      DSAEK, Descemet stripping automated endothelial keratoplasty; DMEK, Descemet membrane endothelial keratoplasty
      Table 2Best corrected distance visual acuity before and after DMEK surgery
      Time of Examinationn
      Here n represents the number of grafts with documented visual acuity at that visit divided by the number of grafts reviewed at that visit.
      Mean ± SD, logMARSnellen Equivalentp Value
      Paired Student's t-test as compared with pre-DMEK values.
      Preoperative91/910.59 ± 0.5020/80
      At 1 month90/900.63 ± 0.6520/800.488
      At 3 months68/720.38 ± 0.4820/500.003
      At 6 months57/650.25 ± 0.4220/40<0.001
      At 12 months55/550.18 ± 0.2820/30<0.001
      DMEK, Descemet membrane endothelial keratoplasty.
      low asterisk Here n represents the number of grafts with documented visual acuity at that visit divided by the number of grafts reviewed at that visit.
      Paired Student's t-test as compared with pre-DMEK values.
      In conclusion, this study of initial cases presenting excellent visual outcomes, fast recovery, and no graft rejections suggests that DMEK is a viable option for endothelial disease. We identify intraoperative and graft preparation factors associated with graft failure so that other novice surgeons may better avoid such pitfalls.

      Footnote and Disclosure

      The authors have no proprietary or commercial interest in any materials discussed in this communication.
      Authorship: All authors attest that they meet the current International Committee of Medical Journal Editors criteria for authorship.

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