The cornea is the clear front of the eye and is essential for the transmission and focusing of light on the retina so that we can see.
Corneal transplantation involves removing the diseased and transplanting a cornea from someone who has kindly donated their eyes for transplantation after death. Because the transplanted cornea is from someone else, there is always a potential risk of transplant rejection. Anti-rejection eye drops or rarely tablets are used to reduce this risk. Occasionally these can be lifelong.
There are several reasons for needing a corneal transplant. These include:
e.g. from corneal infections or sharp injuries
Genetic corneal dystrophies
e.g. lattice, granular or macular corneal dystrophies
Abnormal corneal shape
Melting or perforation (the development of a hole) in the cornea
e.g. in rheumatoid arthritis or from injuries
Types of cornea transplant
Penetrating Keratoplasty (PKP)
The conventional type of corneal transplantation that is still needed in some diseases involves transplanting all the layers of the cornea. It involves several stitches to the eye. Full visual rehabilitation after a PKP can take up to a year.
Sometimes more recently developed transplantation methods are used if suitable as they can be associated with a speedier visual recovery and reduced rates of transplant rejection.
Descemet Membrane Endothelial Keratoplasty (DMEK)
Certain disorders like Fuchs’ dystrophy require a selective transplant. DMEK is a type of endothelial corneal transplant where only a single layer of diseased endothelium is replaced by Descemet membrane and endothelial cells of a healthy tissues. DMEK needs specific microsurgical skills during the preparation of the graft however, with the advanced techniques, DMEK is now gaining popularity in the field of corneal transplants. This type of surgery has been proven to increase the post-operative visual rehabilitation and visual outcomes.
Descemet Stripping Automated Endothelial Keratoplasty (DSAEK)
DSAEK is a selective corneal transplant that involves replacing the posterior layer of the diseased cornea with the healthy tissue. It transplants Descemet membrane and endothelium along with a part of the stroma. This technique is fully standardized, as it involves an automated microkeratome that cuts the tissue in its desired thickness. This technique is still considered as a gold standard due to its known limited damage to the tissue both, during preparation and transplantation and its advantages that are mainly related to improved post operative visual outcomes.
Deep anterior lamellar keratoplasty (DALK)
DALK involves transplanting the anterior stroma leaving the posterior stromal layer and the endothelial cells of the patient untouched. Whereas, in DALK, the entire stroma is replaced with the healthy donor stroma all the way up to the Descemet membrane-endothelial layer. DALK has advantages in terms of minimal endothelial cell loss and better visual recovery.