Corneal Transplant
Corneal transplantation
Corneal transplants, also known as keratoplasty, are surgical procedures that replace damaged or diseased corneas with healthy donor tissue. The cornea is the clear, dome-shaped surface that covers the front of the eye. It plays a crucial role in focusing light and protecting the inner structures of the eye.
This procedure is often recommended for individuals experiencing significant vision impairment due to conditions such as corneal dystrophies, scars from injuries, or infections. During the transplant, the surgeon removes the affected cornea and replaces it with a donor cornea, improving vision and overall eye health.
Thanks to advancements in surgical techniques and post-operative care, corneal transplants have become more successful over the years. Mr Darcy, a specialist in high-volume corneal transplants, provides thorough assessments and customizes treatment plans to fit each patient's unique needs, ensuring the best possible outcomes.
Basic principles
The Human cornea is formed from five layers. Diseases can affect all or specific layers. Modern transplants aim only to replace the damaged layers wherever possible. There are many benefits to this approach.
Penetrating keratoplasty (PK)
Penetrating Keratoplasty corneal transplant. All five layers of the cornea are replaced with new donor tissue, which is sutured in place. The sutures can be gradually removed after about eighteen months. Restoring vision takes a minimum of eighteen months.
This procedure is typically performed to restore vision in patients suffering from conditions such as corneal dystrophies, severe keratitis, or corneal scarring.
Deep anterior lamellar keratoplasty (DALK)
During a DALK procedure, donor tissue is replaced with the outer three layers of the cornea—epithelium, Bowman's layer, and stroma. The new tissue is then sutured in place, similar to how it is done in a penetrating keratoplasty (PK).
DALK is used to treat corneal ectasias, keratoconus, some corneal dystophies and scars affecting only the outer layers.
Deep anterior lamellar keratoplasty (DALK)
Deep Anterior Lamellar Keratoplasty corneal tranplast. During a DALK procedure, donor tissue is replaced with the outer three layers of the cornea—epithelium, Bowman's layer, and stroma. The new tissue is then sutured in place, similar to how it is done in a penetrating keratoplasty (PK).
DALK treats corneal ectasias, keratoconus, corneal dystrophies, and scars that only affect the outer layers.
Mushroom keratoplasty
This technique is a modification of a penetrating keratoplasty. It is technically more challenging but has many potential benefits with theorised lower rates of rejection.
The indications are the same as a PK.
Descemets Stripping Automated Anterior Keratoplasty (DSAEK)
DMEK has largely superseded DSAEK. However, there are certain instances where it remains the treatment choice. During this procedure the endothelium, Descemet's and a thin slice of stroma are inserted into the eye through a small incision. They are held in place with air that absorbs over the coming days.
Adding a thin slice of stroma increases the thickness and rigidity of the transplant. This makes the procedure more straightforward in some more complex eyes that may have had previous trauma, other operations or conditions affecting the normal anatomy of the eye. In eyes with normal anatomy, a DMEK provides a higher quality of vision and a much lower transplant rejection rate.
Descemets Stripping Automated Anterior Keratoplasty (DSAEK)
DMEK has largely superseded DSAEK. However, there are certain instances where it remains the treatment choice. The endothelium, Descemet's, and a thin slice of stroma are inserted into the eye through a small incision. They are held in place with air that absorbs over the coming days.
Adding a thin slice of stroma increases the thickness and rigidity of the tissue. This makes it more suitable for certain eyes that are typically more complex due to abnormal anatomy. This includes eyes with previous trauma, multiple surgical procedures, or congenital anomalies.
Descemets Membrane Endothelial Keratoplasty (DMEK)
DMEK is now the gold standard treatment for endothelial disease. Only the endothelium and Descemet's are replaced (12 microns). The benefits compared to DSAEK are high, with much lower rejection rates and superior visual outcomes. The visual recovery is typically within six weeks. A DMEK procedure is performed under topical (drops) anaesthetic; after the donor preparation, it usually only takes twenty minutes.
First introduced in the early 2010s, this revolutionised the standard of care.
How do a DMEK and DSAEK compare?
The scan images below illustrate the differences between the two procedures. The first image, the DMEK procedure restores the normal anatomy of the eye, while the second image the DSAEK procedure increases the thickness of the cornea due to the added stromal tissue. This extra rigidity can be beneficial for patients with other eye conditions where a DMEK may not be technically feasible. For cases of simple endothelial failure, DMEK has now become the gold standard.
DSAEK
DMEK