On This Page
DMEK procedures can be done at various points in the disease process for these suitable patients. There is no recommended level of visual acuity reduction or glare acuity that dictates when the procedure should be done. Patient symptoms should be the driver for when to proceed with surgical intervention.
Patients with endothelial disease will often experience blurred vision, glare/halos, trouble driving at night, “watery” or edematous vision, and even pain if the corneal swelling affects the ability of the epithelium to adhere properly. As the endothelial disease progresses, these “water pump” cells are unable to maintain dehydration and fluid enters the corneal stroma. As the cornea worsens with edema, the fluid can move anterior into the epithelium, resulting in painful blisters called bullae.
Patients with corneal edema secondary to endothelial disease will notice decreased vision quality in the morning, secondary to increased corneal swelling secondary to being in a closed-eye state overnight. They will also struggle with glare in dim conditions, like during nighttime driving.
When evaluating a patient with changes to the endothelial cell layer, several instruments are used during the visit. We will use an instrument that can analyze the endothelial cell size, morphology, density and drop out. We also use pachymetry measurements as well as corneal topography and tomography maps to analyze and monitor the areas of corneal irregularity and edema secondary to the endothelial changes. Finally, a detailed slit lamp exam examination is important to view and diagnose unhealthy endothelial cells.
EK procedures are not suitable for patients with healthy corneal endothelium, such as patients with stromal scarring or keratoconus. These patients still require a full thickness corneal transplant.
Good candidates for DMEK
Fuchs’ endothelial dystrophy
Posterior polymorphous membrane dystrophy
Congenital hereditary endothelial dystrophy
Iridocorneal endothelial (ICE) syndrome
Other failed endothelial keratoplasty procedures
The first step in DMEK is to prepare the graft tissue. This is commonly done by the Eyebank under their standard protocol. After preparation, the tissue is safely transported to the surgery center and further prepped for the patient.
If the DMEK graft is being performed in conjunction with cataract surgery, the cataract is removed, and an intraocular lens is inserted before the corneal transplantation portion of the procedure. Using a laser, a peripheral iridotomy (a small channel or passageway) is made in the host iris to allow aqueous movement in the eye. The host tissue endothelium and Descemet’s membrane are stripped from the posterior cornea and removed from the eye. Prior to inserting the endothelial graft tissue, it is stained with Trypan blue before it is rolled up and placed into an inserter. The graft is injected into the eye and it slowly starts to unfold. The surgeon will manipulate and place the graft into place by using pressure, fluid mechanics and gently tapping on the cornea. Once the graft is in position a gas bubble is injected into the eye to aid the graft tissue in adhering to the posterior cornea. After the bubble is safely placed the patient’s eye, the IOP is checked. This completes the surgical process.
Drop protocol subject to change
Durezol/prednisolone acetate 1%: instill 1 drop 4 times per day for 2 months, then 2 times per day for 4 months, then 1 time per day for 6 months.
Ilevro/Prolensa: instill 1 drop 1 time per day for 1 month or the bottle runs out.
Vigamox: instill 1 drop 4 times per day for 1 week or the bottle runs out.
Side Effects and Post-op Complications
Graft detachment: rates are variable and depend on surgeon experience and donor tissue quality
Damage to tissue during preparation or surgery
Upside down grafts
Epithelial defect or erosion
Raised intraocular pressure (IOP). In the first week, if a patient has a real sore/achy eye, a bad headache around the eye, or feels nauseated or like vomiting, the surgeon and his/her team should be called immediately.
Descemet’s graft folds
<1% risk of anterior synechiae, hypotony, pupillary block, subepithelial haze, and interface pigment deposits.32
Cystoid macular edema (CME)
What to look for: