Cornea Transplantion (Keratoplasty)
What is Cornea?
The cornea is the transparent tissue at the very front of the eye, which has the task of focusing light and protecting the eye. The optical properties of the cornea are as important for its visual function as its transparency. Patients with corneal tissue with impaired transparency are replaced with a donor, i.e., transparent cornea.
What is Cornea Transplantation?
Cornea transplantation, also known as eye transplantation, is the replacement of corneal tissue whose transparency has deteriorated as a result of certain diseases with a healthy donor's transparent cornea.
In Which Diseases Is Cornea Transplantation Performed?
The transparency and optical properties of the cornea can be impaired by many diseases. Some of these diseases include advanced keratoconus, i.e., bulging and thinning of the cornea, corneal infections, corneal injuries, chemical burns of the cornea, hereditary dystrophies of the cornea, corneal edema that does not improve with treatment (caused by previous eye surgery, especially cataract surgery).
How is cornea transplantation surgery performed?
Cornea transplantation is one of the most successful transplant surgeries. Today, cornea transplantation can be performed as full thickness, i.e., penetrating keratoplasty, or as half-thickness, i.e., lamellar keratoplasty, depending on which corneal layer is affected by the disease.
How is Cornea Transplantation Performed?
The surgery can be performed under local or general anesthesia.
The patient's corneal tissue, which has lost its transparency or is misshapen, is removed in full thickness, replaced with a tissue of approximately the same size from a healthy donor cornea, transplanted to the patient, and the donor cornea is sutured to the recipient cornea with approximately 16 individual or single continuous sutures or both methods together.
The duration of the operation is approximately 45-60 minutes. If there are other interventions to be performed at the same time, the operation time may be prolonged.
Today, cornea transplantation can be performed as full-thickness (penetrating) or half-thickness (lamellar). For example, if the inner layer of the cornea, the endothelium, is intact but the anterior layer is diseased, only the anterior layer of the cornea is replaced. This surgical method is called Deep Anterior Lamellar Keratoplasty (DALK). If the endothelial (inner) layer of the cornea is insufficient, only this layer is replaced, and this surgery is called Descemet Membrane Endothelial Keratoplasty (DMEK). Although the success rate of this surgery varies according to the patient, it is generally high.
DALK (Transplantation of the Front Layer of the Cornea)
In DALK surgery, the diseased anterior layer of the cornea (epithelium and stroma layers) is replaced, while the endothelial cells, the innermost layer, remain in place. Since the endothelial cells of the donor tissue are not removed, the risk of rejection of the transplanted cornea is significantly reduced. Accordingly, the duration of medication use after transplantation is shortened. Wound healing is faster, and stitches are removed in a shorter time.
DMEK (Transplantation of the Endothelial Layer of the Cornea)
It is the replacement of only the inner layer of the cornea (endothelium and Descemet's membrane) and not the full layer. DMEK surgery is often performed for Fuchs' Endothelial Corneal Dystrophy, an eye disease caused by degenerative changes in the innermost cell layer of the cornea, or sometimes for persistent corneal edema that does not heal after cataract surgery. The most important feature of this surgery is that, unlike full-thickness cornea transplantation, there are few stitches, and it is known as "seamless cornea transplantation". In addition, since the anterior layers of the cornea are the patient's own tissue, the cornea is more resistant to trauma than a full-thickness transplant cornea. Cornea transplantation is a specialized surgical procedure.