Descemet Membrane Endothelial Keratoplasty (DMEK) is an advanced partial-thickness cornea transplant procedure for the treatment of Fuchs’ Dystrophy, keratoconus, scarring and corneal edema.
The DMEK Procedure
In the first step of the DMEK procedure, Dr. Berger outlines the central 8.75 mm of the cornea that is to be removed and replaced with the donor cornea.
Next, two 1-mm paracentesis ports are placed. One at the superior temporal aspect of the eye and the other at the inferior temporal aspect of the eye.
Vision Blue or trypan blue dye is then injected into the anterior chamber using a cannula through one of the paracentesis ports to stain the endothelium blue. This is to help visualize the endothelial layer for removal.
Next, the dye is irrigated from the eye with preservative-free lidocaine. This serves to simultaneously anesthetize the eye and remove the excess blue dye. A medication such as Miochol or Miostat is then injected into the anterior chamber using a cannula through the paracentesis port in order to constrict the pupil. A small pupil is necessary to restrict the air to the anterior chamber later in the surgery.
Please note the previously-placed inferior peripheral iridotomy. Typically performed in the clinic days or weeks prior to the cornea transplant, an iridotomy or small hole in the iris, will reduce the risk of post-operative pupillary block from the air or gas used to keep the graft in place as it permanently attaches to the patient’s cornea.
Next, a cohesive viscoelastic such as Provisc or Healon is injected into the anterior chamber with a cannula through the paracentesis port to deepen and reform the anterior chamber.
A temporal 2.0‑mm to 2.4-mm clear cornea wound is placed using a standard cataract keratome blade.
Next, Descemet’s membrane is scored using the previously-placed 8.75-mm outline on the cornea using a specially‑designed reverse Sinskey hook.
Descemet’s membrane, the diseased inner layer measuring only 8 to 10 microns in thickness, is then stripped from the inner cornea using either a reverse Sinskey hook or a 45-degree stripper instrument. The membrane is then removed from the eye through the keratome wound.
Dr. Berger then uses an automated irrigation and aspiration device to completely clear the viscoelastic from the anterior chamber.
The Micro Modified Jones Tube containing the DMEK graft is inserted through the keratome wound and the graft is gently injected into the anterior chamber. The empty Micro Modified Jones Tube is removed from the eye.
The keratome wound is then closed with a single 10-0 nylon suture with the knot tied and rotated.
The graft is then unfolded within the eye by tapping on the cornea and massaging the graft into place. Proper centration is confirmed with the previously placed 8.75 mm cornea mark and by visualizing the “S” stamp placed by the eye bank during their tissue preparation.
Once centered within the imprinted 8.75-mm area, air or a 20% SF6 gas/air combination is injected slowly under the graft. BSS is then used to perform a gas fluid exchange using a cannula through one of the paracentesis ports. Enough fluid is left in the anterior chamber to allow fluid to flow between the posterior and anterior chamber through the peripheral iridotomy minimizing the risk of pupillary block from the air or gas in the anterior chamber. The entire procedure is over in as little as 10-15 minutes.
Postoperatively the patient will lay face up for 3-7 days, getting up every 1-2 hours for 10-15 minutes. Vision is typically restored by 2 weeks.
For an appointment to get an evaluation with Dr. Berger, call 813-265-6940.