The cornea is the clear dome covering the front of the eye. Despite being a small structure, it is a well organized tissue with 6 distinct layers – one being newly discovered in just the last 3 years! That being said, the knowledge of these layers is what gives us the ability to innovate and perfect new techniques in corneal transplantation.
Many different disease entities contribute to the need for a cornea transplant. They include autoimmune diseases, infections, hereditary corneal diseases (like fuchs), and infiltrative processes (like lipid keratopathy.
It used to be that the only reliable option was to transplant all the layers of the cornea. With the advent of new techniques and exploiting our new found knowledge of the cornea, we can now offer options that are less disruptive and invasive to the cornea. They are colloquially known as partial cornea transplants.
One such “partial cornea transplant” is called, DMEK. This is the thinnest tissue that can be transplanted onto the cornea. It’s employed when the endothelial cells on the back layer of the cornea are dysfunctional. This can cause swelling and opacification of the cornea, which can translate into blurry vision.
DMEK surgery is employed to replace the dyfunctioning cells and restore a clear cornea and improve vision. The technique starts by the surgeon removing the diseased endothelial cells and then injecting and affixing the donor corneal tissue to the back of the patient’s cornea. This is done by using SF6 gas or an air bubble. Over time the gas bubble disappears and the donor cells kick into gear and de-swell the cornea. The patient will take eye drops afterward to prevent rejection of the new donor corneal tissue.
DMEK is only one of the new options for patients. Other options include DALK surgery for the diseases on the front part of the cornea, such as corneal scars and keratoconus, as well as DSEK surgery for patients with more complex type of endothelial issue. We will discuss these options in future blogs.
Cornea transplant technology keeps getting better and allows for faster healing, less rejection, less trauma to the eye and faster visual recovery. For some patients, conventional full-thickness cornea transplants are still indicated, but thankfully the majority of patients are a candidate for one of these new procedures and don’t need to go through a such a long recovery period.