Phakic DMEK Under PK

Contributors: James M. Huffman, MD and Mark A. Greiner, MD

Additional Note: Length 04:13

Posted May 31, 2019

 

 

We have found that DMEK under PKP can work well if the PK wound architecture is good and doesn't contain ridges and folds that can interact unfavorably with adhesion. It is also important to rule out anterior stromal scarring in the PK graft that could limit visual recovery with an endothelial transplant as these patients are better served with a repeat PKP.

We also recommend undersizing the DMEK graft by at least 0.5mm depending on the size of the graft.  The first trephination is performed by the eye bank.  Once the PK is measured the second partial-thickness trephination is performed in the operating room.   The goal is to avoid overlap with the graft-host junction thus decreasing the risk for a postoperative edge lift requiring a rebubble.

1. The first paracentesis is made with a 1.0mm blade.  A small amount of Miochol is instilled into the anterior chamber with a 30-gauge canula.
2. Healon is then instilled with a 30-gauge canula.
3. The remaining paracentesis are placed in each quadrant with a 1.0mm blade.
4. A peripheral iridotomy is performed.  In phakic patients, the Alcon Centurian vitrectomy handpiece is used.
5. Descemet membrane is then scored with a reverse Sinskey hook.  In DMEK under PK cases the graft-host junction is avoided as excess manipulation can lead to wound dehiscence. 
6. The Descemet membrane is then stripped with a reverse Sinskey hook. 
7. A 2.2mm clear corneal incision is made temporally.  The wound is then enlarged with a 2.5mm crescent blade to a size of 2.6mm.
8. Descemet membrane is then removed and submitted to pathology
9. Excess Healon is then removed with the irrigation/aspiration handpiece.
10. Additional Miochol is instilled into the anterior chamber and attention is turned to the back table.
11. The corneal tissue is then removed from the Optisol GS with .5 forceps and placed on a Barron punch.
12. In this case the PK was measured at 7.0mm so a 6.5mm Barron punch was used.
13. The pre-punched tissue is then stained with Trypan blue
14. The second partial-thickness trephination is performed by gently tapping on the anterior surface of the Barron punch.
15. Excess Descemet membrane is then removed with curved forceps and the graft is lifted from the posterior stroma.  The graft is then submerged in a well of Trypan blue for 90 seconds.
16. The graft is then placed in a BSS bath and drawn up into a modified Jones tube.
17. Proper graft orientation is confirmed and the graft is delivered into the anterior chamber.  The anterior chamber is then flattened and the tube is removed.
18. The graft is unfolded with 30-gauge cannulas or in this case with a 23-gauge cannula and Cindy sweeper.  The graft is then swept into the correct position.  No overlap is noted with the graft-host junction
19. A small 20% SF6 bubble is placed to support the graft.  Once the intraocular pressure is appropriate and the wounds are stable the larger 20% SF6 bubble is delivered.
20. The clear corneal incision is closed with a 10-0 nylon suture.
21. A collagen shield is placed on the ocular surface

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