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
- A 3.2-mm clear corneal incision is made at a depth of 300 μm at the temporal limbus
- Two paracentesis incisions are made superior and inferior to the main incision
- In pseudophakic cases, the pupil is constricted with acetylcholine (Miochol; Bausch and Lomb, Rochester, NY)
- 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
- Cohesive viscoelastic material (Healon; Abbott Medical Optics) is used to fill the AC for intraocular maneuvers before graft placement
- 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)
- AC is refilled with a cohesive viscoelastic material
- 0mm diameter central recipient Descemet membrane is stripped and removed
- Viscoelastic material is removed with I/A handpiece
- Short acting pupillary constriction is achieved with acetylcholine and the pressure is normalized
Donor Table:
- Pre-stripped tissue from eye bank with S Stamp and hinge attachment identified by notch in sclera
- Trypan blue is placed to stain the tissue and identify the edges
- Donor corneal/sclera tissue is placed endothelial side up on trephine block (Moria) and centered
- Donor diameter is slightly undersized (7.5 or 7.75mm) and with direct visualization a trephine is lowered onto the tissue
- Tapping and gentle pressure are used to cut Descemets and the trephine is removed
- Donor tissue peripheral to the cut is removed
- Donor graft is covered with BSS
- Donor graft gently picked up with tying forceps to complete the stripping of the hinge area
- Donor corneal-scleral tissue well is the filled with trypan and the tissue deposited back into the pool of trypan for 4 minutes
- Injector device is prepared using a 15mm length single lumen #14 French nasogastric catheter plastic tubing as a coupler
- One end to the modified Straiko/Jones tube and the other end to a 3 or 5cc syringe
- 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
- After 4 minutes the donor tissue is visualized initially by diluting the trypan with progressive infusions of BSS and absorption with sponges
- 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
- 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
- Injector tube may be rotated to ensure proper orientation of graft
- Tissue injected while AC pressure is lowered by releasing fluid from paracentesis
- 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
- Place 1 interrupted 10.0 nylon (or 10.0 vicryl) suture in wound
- Chamber is kept very shallow for unscrolling
- Modified Yoeruek tap technique with NO air bubble to create fluid waves to unscroll the transplant
- Dirisamer double cannula compression technique for unfolding taco orientation
- Peripheral limbus taps for moving entire graft to center
- 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
- 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
- Originally a 8-9mm bubble is injected
- 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)
- Gas released and replaced with BSS leaving an ~80% fill ensuring the inferior PI is uncovered in the supine position
- Collagen shield soaked in steroid and antibiotic is placed
- Patch and shield the eye and leave in place until it is removed at the POD 1 appointment
- The patient is held in the holding area in the supine position for 1 hr prior to discharge
Patient Instructions:
- Lie supine (on your back) as much as possible (allow 20 minutes at a time for meals and toileting) for the first 48 hours
- Encourage the patient to sleep in the supine position
- Topical antibiotics QID for 1 week
- Prednisolone acetate 1% QID for 3 months and then taper to qday over the next 9 months
Relative Contra-indications to DMEK
- Vitrectomized Glboe
- Monochamber globe/aphakia
- AC IOL
- Opaque Cornea
- Tube Shunt
- Silicone oil in AC
- Iris defect
- Dilated, non-constricted pupil
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
Copyright statement: Swan, Tabin, ©2015. For further information regarding the rights to this collection, please visit: http://morancore.utah.edu/terms-of-use/