With some types of cornea problems, a full-thickness cornea transplant isn’t always the most appropriate treatment. Other types of transplants may be used that remove only certain layers of cornea tissue, or only tissue affected by disease. These types of procedures include:
Endothelial keratoplasty (EK). This procedure removes diseased tissue from the back corneal layers, including the endothelium, along with the Descemet membrane, a thin layer of tissue that protects the endothelium from injury and infection. Donor tissue is carefully implanted to replace the removed tissue.
There are two types of endothelial keratoplasty. The most common type, called Descemet stripping endothelial keratoplasty (DSEK), uses donor tissue to replace about one-third of the cornea. A newer type of procedure, called Descemet membrane endothelial keratoplasty (DMEK), uses a much thinner layer of donor tissue. Because the tissue used in DMEK is extremely thin and fragile, this procedure is more challenging than DSEK, and not as commonly used.
Anterior lamellar keratoplasty (ALK). This procedure removes diseased tissue from the front corneal layers, including the epithelium and the stroma, but leaves the back endothelial layer in place.
The depth of cornea damage determines the type of ALK procedure that’s right for you. Superficial anterior lamellar keratoplasty (SALK) replaces only the front layers of your cornea, leaving the healthy endothelium intact. A deep anterior lamellar transplant (DALK) procedure is used when cornea damage extends deeper into the stroma.
In DALK, a small incision is made in the side of your eyeball to allow for removal of your cornea’s front and middle layers without damaging the back layers. Healthy tissue from a donor is then attached (grafted) to replace the removed portion.