How does a corneal transplant work?
A corneal transplant is a procedure where we remove a damaged or diseased cornea from a patient and we replace this with healthy corneal tissue from someone who has passed away and donated their cornea.
Early corneal transplants.
In the early 50s, 1950s, 1860s when corneal transplantation was first being performed routinely there was only one type of corneal transplant and indeed that continued right up until the 1980s and early 1990s. There was only one type of corneal transplant and that was a full thickness corneal transplant where we would remove the whole full thickness of the cornea so a disc, full thickness, from the center of the cornea, and we would replace that with an equivalent disc, full thickness, from a donor.
But throughout the early 90s onwards, particularly in the last 10, 15 years, we’ve seen a complete revolution in corneal transplant surgery. It’s now very, very rare to do a full thickness transplant of the cornea, instead what we’ve moved to is selectively replacing only the layers of the cornea that are damaged.
Different types of treatments.
So some patients who for instance have a scar in the surface of the cornea from an infection, we only need to replace the superficial parts of the cornea and we no longer need to even enter the eye, we can simply remove the anterior two thirds or whatever is required to get beneath the scar and replace that with an equivalent partial thickness corneal transplant from a donor.
The other type of transplant we do is, in many patients, the surface of the cornea is entirely healthy and the main body of the cornea is entirely healthy as well, it’s simply the inner lining or what we call the endothelial cells, that are damaged, in some patients.
And the types and conditions are typically things like Fuchs’ endothelial dystrophy or patients who’ve had many eye operations, we call this pseudophakic bullous keratopathy.
So in these two conditions endothelial cells that line the cornea have been damaged or have died off prematurely because of aging it’s possible to replace this layer of cells through a keyhole incision and remove the dead or the layer of cells that are damaged and replace this with a very thin layer of cells from a donor, and we call this either a DSAEK. DSAEK procedure, or a MMEK, a DMEK procedure.