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Descemets Membrane Endothelial Keratoplasty (DMEK)

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Title: Descemets Membrane Endothelial Keratoplasty (DMEK)
Author(s): Russell Swan, MD, Geoff Tabin, MD
Date: 11/12/2015
Keywords/Main Subjects: Descemets Membrane Endothelial Keratoplasty; DMEK; Cornea transplant; EK; Fuchs
Secondary CORE Category: Ophthalmic Surgery
Diagnosis: Descemets Membrane Endothelial Keratoplasty
Brief Description:
DMEK surgical technique as adapted from recommendations from Dr Mark Terry and Michael Straiko

  1. A 3.2-mm clear corneal incision is made at a depth of 300 μm at the temporal limbus
  2. Two paracentesis incisions are made superior and inferior to the main incision
  3. In pseudophakic cases, the pupil is constricted with acetylcholine (Miochol; Bausch and Lomb, Rochester, NY)
  4. In triple procedures (DMEK combined with phacoemulsification cataract surgery), the pupil is dilated with minimal to no cycloplegia agents preoperatively and the phacoemulsification and IOL placement are performed first
  5. Cohesive viscoelastic material (Healon; Abbott Medical Optics) is used to fill the AC for intraocular maneuvers before graft placement
  6. Inferior PI performed with angled 30 gauge needle tip passed posterior to the pupil and a Sinskey hook (Bausch and Lomb) is used to scrape down on the needle tip to create a hole (this can be done pre-operatively with a laser PI)
  7. AC is refilled with a cohesive viscoelastic material
  8. 0mm diameter central recipient Descemet membrane is stripped and removed
  9. Viscoelastic material is removed with I/A handpiece
  10. Short acting pupillary constriction is achieved with acetylcholine and the pressure is normalized

Donor Table:

  1. Pre-stripped tissue from eye bank with S Stamp and hinge attachment identified by notch in sclera
  2. Trypan blue is placed to stain the tissue and identify the edges
  3. Donor corneal/sclera tissue is placed endothelial side up on trephine block (Moria) and centered
  4. Donor diameter is slightly undersized (7.5 or 7.75mm) and with direct visualization a trephine is lowered onto the tissue
  5. Tapping and gentle pressure are used to cut Descemets and the trephine is removed
  6. Donor tissue peripheral to the cut is removed
  7. Donor graft is covered with BSS
  8. Donor graft gently picked up with tying forceps to complete the stripping of the hinge area
  9. Donor corneal-scleral tissue well is the filled with trypan and the tissue deposited back into the pool of trypan for 4 minutes
  10. Injector device is prepared using a 15mm length single lumen #14 French nasogastric catheter plastic tubing as a coupler
  11. One end to the modified Straiko/Jones tube and the other end to a 3 or 5cc syringe
  12. Syringe and injector are filled with BSS and tested using the previously stripped peripheral donor tissue fragments (aspirate and inject into a petri dish filled with BSS
  13. After 4 minutes the donor tissue is visualized initially by diluting the trypan with progressive infusions of BSS and absorption with sponges
  14. Tip of Straiko/Jones tube is submerged bevel up into the well and the tissue scroll aspirated to a position just proximal to the tip. The injector is brought to the operative field then.

Placement of Graft

  1. Pressure in the chamber is reduced to near zero and the tip of the injector is placed into the AC through the main 3.2 mm wound
  2. Injector tube may be rotated to ensure proper orientation of graft
  3. Tissue injected while AC pressure is lowered by releasing fluid from paracentesis
  4. Remove the injector while externally compressing the wound central to the tip with a cannula to prevent the tissue from following the injector tip out of the wound
  5. Place 1 interrupted 10.0 nylon (or 10.0 vicryl) suture in wound
  6. Chamber is kept very shallow for unscrolling
  7. Modified Yoeruek tap technique with NO air bubble to create fluid waves to unscroll the transplant
  8. Dirisamer double cannula compression technique for unfolding taco orientation
  9. Peripheral limbus taps for moving entire graft to center
  10. Once centered use slow injection of 20% SF6 gas using a 1cc syringe and a 27 gauge cannula. Place cannula through a paracentesis site, nto the surface of the iris, below the donor
  11. Take care NOT to inject until the tip of the cannula is visualized in the genter of the graft and the eye in primary position
  12. Originally a 8-9mm bubble is injected
  13. Once orientation of graft is confirmed and no scrolls remain then complete AC fill is performed and left for a few minutes (if any paracentesis are leaking they can be sutured as well)
  14. Gas released and replaced with BSS leaving an ~80% fill ensuring the inferior PI is uncovered in the supine position
  15. Collagen shield soaked in steroid and antibiotic is placed
  16. Patch and shield the eye and leave in place until it is removed at the POD 1 appointment
  17. The patient is held in the holding area in the supine position for 1 hr prior to discharge

Patient Instructions:

Relative Contra-indications to DMEK

Format: .video
Identifier: Moran_CORE_17963
References:
Terry, M. et al. Standardized DMEK Technique: Reducing COmplciations Using Pre-stripped Tissue, Novel Glass Injector, and Sulfur Hexafluoride (SF6) Gas. Cornea. 2015. Aug 34(8) 845-52
Faculty Approval by: Geoff Tabin