Descemet Membrane Endothelial Keratoplasty (DMEK) has become the preferred surgical technique for the treatment of Fuchs’ corneal dystrophy. In the case shown here, the patient was noted to have a cataract as well as corneal decompensation at the initial consultation. The endothelial cell count was 600 cells/square millimeter and the corneal pachymetry was 698 microns. The decision was made to perform a combined cataract surgery plus DMEK.
The cataract surgery is done first and we alter some of the steps in order to facilitate the DMEK surgery:
- The phaco incision is well-constructed and we place it as peripheral as possible so that it does not intersect the area where the DMEK graft will sit.
- Stain the anterior lens capsule with trypan blue dye even if there is a reasonable red reflex. The view through the compromised cornea is not great and the blue dye will make visualization of the capsulorhexis much easier.
- We make a smaller capsulorhexis (4.5mm is ideal) so that the IOL will not get displaced from the capsular bag if there is pressure exerted from the gas bubble that we place at the end of the case.
- We adjust the IOL power to account for the expected refractive shift from the DMEK graft. This means aiming for a post-op goal that is about 0.5 diopters more myopic than you desire. For example, to achieve plano, aim for -0.5 post op Rx. Or you could add 0.5 to 1.0 D to your IOL power.
For the DMEK procedure, we are using a graft size of 7.5 mm and we order it from the cornea bank pre-cut, pre-stained, pre-marked, and pre-loaded. This means that the graft comes ready to use and loaded into a Jones tube.
The challenge with DMEK is learning to unfold and unroll the graft, then get it into the correct position prior to insertion of the gas bubble. I have learned so much about DMEK techniques from Peter Veldman MD, Martin Dirisamer MD, and Rajesh Fogla MD. They are master DMEK surgeons and I hope to advance to their level of expertise in the future.
If you wish to learn the various DMEK unfolding techniques, this video from Dr Veldman is great because it shows every possible configuration and how to solve them. In this resident case the graft is initially placed in the eye upside down, but we use these techniques and easily return it to the correct configuration. For the gas bubble we are using a 16% SF6 which is made by combining 0.5cc of SF6 with 2.5cc of filtered room air (0.5 cc divided by 3.0 cc total = 16%).
Click below to learn how this resident performed a combined phaco + DMEK: