Corneal Transplant Surgery: DMEK, DALK and Full-Thickness Grafts Explained

Hearing that you may need a corneal transplant can feel daunting. Many people picture the entire cornea being removed and replaced with donor tissue.

That operation, called a full-thickness transplant, still has an important role. However, modern corneal surgery can often replace only the layers affected by disease.

Understanding which part of your cornea is damaged helps explain why one operation may be recommended over another—and why recovery can differ considerably.

Why the cornea’s layers matter

The cornea is the clear window at the front of your eye. Its layers work together to protect the eye and focus light.

Keratoconus primarily changes the shape and strength of the cornea, while its inner endothelial pumping layer often remains functional. Fuchs endothelial dystrophy primarily affects those pump cells, allowing fluid to accumulate and cloud the cornea. In advanced Fuchs dystrophy, prolonged swelling can also cause changes and scarring in the front layers.

Where suitable, replacing the affected tissue while preserving healthy layers can offer advantages. The main approaches are DMEK, DALK and penetrating keratoplasty.

DMEK: replacing the inner pumping layer

DMEK stands for Descemet membrane endothelial keratoplasty. It replaces the endothelial cells and the thin membrane supporting them.

Endothelial cells help keep the cornea clear by pumping fluid out. They have very limited ability to replace themselves in the human eye. When too many stop functioning, the cornea becomes swollen and vision may become blurred.

DMEK is commonly considered for Fuchs endothelial dystrophy and some cases of endothelial failure after previous eye surgery, particularly when there is little significant scarring in the remaining cornea.

During surgery, an extremely thin layer of donor membrane and endothelial cells is introduced through a small incision, unfolded and positioned against the back of the cornea. An air or gas bubble holds the tissue in place while it attaches. The graft itself is not stitched into position, although the incision may require a stitch.

For a comparison with another endothelial transplant technique, read DMEK vs DSAEK: Understanding the Latest Corneal Transplant Techniques.

What is recovery like after DMEK?

Vision often improves during the first few weeks, but recovery varies and can continue over several months. The bubble initially blurs vision, and other eye conditions may limit the final result.

Patients receive instructions about lying face-up to help the bubble support the graft. The required positioning schedule depends on the surgeon’s protocol and individual circumstances.

Sometimes the graft partially detaches and needs another air or gas injection, called rebubbling. Other risks include raised eye pressure, infection, rejection and graft failure.

While the bubble remains, patients must follow restrictions on flying and altitude. They must also tell any treating anaesthetist or emergency clinician about the bubble before receiving nitrous oxide, including “gas and air” pain relief. Prescribed drops and follow-up appointments are essential.

DALK: replacing the front layers and preserving the back

DALK stands for deep anterior lamellar keratoplasty. It replaces the front and middle corneal tissue while preserving the patient’s own Descemet membrane and endothelial cells.

It may be considered for advanced keratoconus when vision cannot be adequately managed with glasses or contact lenses, or when significant scarring is present. It can also suit some other corneal scars, provided the inner layers remain healthy.

During DALK, the surgeon removes the affected tissue and sutures donor tissue onto the retained inner layers.

Preserving the patient’s endothelium avoids endothelial graft rejection. However, rejection affecting the transplanted stromal tissue is still possible, along with infection, interface haze and other complications.

If the retained inner membrane tears during surgery, conversion to a full-thickness transplant may be necessary.

Read more about femtosecond laser-assisted DALK and how laser technology can assist selected procedures.

What is recovery like after DALK?

DALK involves a longer period of visual recovery than DMEK. Sutures remain in place for many months and may be adjusted or removed gradually as the cornea heals.

Vision can change during this process. Glasses or contact lenses may still be needed to correct remaining astigmatism or other prescription changes.

Keeping the patient’s own endothelial cells can be particularly valuable for younger people who may live with their graft for decades. However, it does not guarantee lifelong graft clarity or eliminate the need for ongoing care.

Full-thickness grafts: when every layer needs replacing

Penetrating keratoplasty, or PK, replaces a central full-thickness section of the cornea with donor tissue secured by sutures.

It may be needed when damage involves multiple layers, such as deep scarring after severe infection or injury. It can also be appropriate when a partial-thickness operation is unsuitable or a previous graft has failed.

Recovery is usually longer than after DMEK. Sutures are managed over an extended period, and the cornea’s shape and prescription can change as it heals. Glasses or specialised contact lenses are often needed afterwards.

Risks include rejection, infection, raised eye pressure, astigmatism and graft failure. The surgical wound also remains vulnerable to injury, making eye protection important.

For selected patients, a full-thickness graft offers the possibility of improved vision when other treatments are unsuitable. The outcome depends on the condition of the rest of the eye as well as the graft.

For further explanation, read Understanding Keratoplasty: Penetrating vs Deep Anterior Lamellar Procedures.

How is the right operation chosen?

The choice depends on more than the diagnosis alone. Assessment considers:

• Which corneal layers are affected.
• The depth and location of scarring.
• Corneal shape and thickness.
• Whether the endothelial cells are functioning.
• Previous surgery, eye pressure and other eye conditions.
• Your visual needs and ability to manage recovery.

Examination, corneal mapping and imaging help guide the recommendation. Sometimes the most appropriate approach is continued monitoring or another treatment rather than transplantation.

For keratoconus, cross-linking can reduce the risk of further progression. Glasses, contact lenses and other selected treatments may help manage vision. Cross-linking does not remove established scarring or guarantee that a transplant will never be needed.

Looking after a corneal graft

Every type of corneal transplant requires ongoing monitoring.

Use prescribed drops as directed, including steroid drops when recommended, and do not stop them without advice. Follow-up checks assess healing, eye pressure, graft clarity and any signs of rejection.

New redness, light sensitivity, pain or reduced vision after a transplant needs same-day ophthalmic advice. Rejection can occur long after surgery, and early treatment may help protect the graft. Some rejection episodes cause few symptoms, so scheduled reviews remain important.

Book a corneal assessment with Dr Brendan Cronin

If you have been told you may need a corneal transplant, an assessment can help you understand which layers are affected and which treatments may be suitable.

Dr Brendan Cronin can review your corneal health, explain the available options and discuss the benefits, risks and recovery relevant to your eyes.

Contact Queensland Eye Institute to book an appointment with Dr Brendan Cronin.