What is a Corneal Transplant?

The transparent layer in front of the iris, which is the colored part of the eye, is called the cornea. After the rays coming to the eye first pass through this tissue, they reach the nerve layer we call the retina and vision occurs.

The transparency or regular shape of the cornea therefore plays an important role in vision. If the cornea loses its transparency (hereditary diseases such as corneal dystrophy, corneal edema that does not go away after cataract surgery, etc.) or deforms (progressive thinning and erection of the cornea such as keratoconus), the patient cannot see clearly.

In such cases, vision can be regained by replacing the cornea with another healthy corneal tissue. In this transplant process, the tissue is healthy corneal tissue taken from a deceased person and the process is called corneal transplant.

Corneal transplantation can be performed with full-thickness corneal tissue, or only the upper layer or lower layer of the cornea can be transplanted.

One of the properties of the cornea that makes it transparent is that it is avascular. The absence of vessels in the tissue provides an important advantage in tissue transplantation. Because it is not possible for the cells that cause tissue rejection to reach the foreign tissue.

Corneal transplantation can be performed with full-thickness corneal tissue, or only the upper layer or lower layer of the cornea can be transplanted.

One of the properties of the cornea that makes it transparent is that it is avascular. The absence of vessels in the tissue provides an important advantage in tissue transplantation. Because it is not possible for the cells that cause tissue rejection to reach the foreign tissue.

When we consider all transplant surgeries, the fact that corneal transplants are more successful than other transplants is due to this feature.

Steps of Full Thickness Corneal Transplantation (Penetrating Keratoplasty) Surgery

After disinfecting the eye and its surroundings under local or general anesthesia, it is covered with a sterile cloth.

The center of the cornea is marked.

With a vacuum instrument (trepane) containing a round blade, a circular full-thickness incision of 7-7.5 mm in diameter is made in the center of the cornea and the center of the cornea is removed.

The donor cornea is prepared in accordance with the recipient area with another vacuum tool (punch) containing a circular blade.

The donor cornea is sutured to the recipient area with different stitching techniques (16 single stitches, 16 single stitches with continuous stitches, continuous double stitches, etc.).

The procedure is ended by applying an antibiotic drug to the eye.

The duration of the operation is approximately 30-40 minutes. If there are other interventions to be performed at the same time, the duration of the operation may prolonged.

What should be considered after the operation?

There may be complaints such as stinging and watering for a few weeks after the surgery. A protective bandage is used on the day of surgery.

The level of vision may not immediately increase much. Postoperative antibiotic and cortisone eye drops are used in accordance with the physician's recommendation. The first control is done on the first day after the surgery. Then, control is carried out every day during the first week after the operation. Stitches are usually removed after 1 year.

Potential Risks and Sides Effects

· Expulsive bleeding

· Astigmatism

· Infection

· Tissue rejection

Femtosecond Laser at Full Thickness Corneal Transplant Surgery

In full-thickness corneal transplantation, instead of a vacuum instrument (trepane) containing a round blade used in the preparation of the recipient area, a circular full-thickness incision of 7-7.5 mm diameter is made in the center of the cornea with a femtosecond laser and the center of the cornea is removed. The other steps of the surgery are the same. Recovery time is much faster at the operations done with femtosecond laser.

DALK (Deep Anterior Lamellar Keratoplasty)

The process of replacing only the top layer of the cornea, not the full layer, is called DALK. DALK stands for “deep anterior lamellar corneal transplant”. It is most commonly performed in keratoconus disease.

In hereditary diseases of the cornea, DALK can be applied if the disease affects the upper layers of the cornea.

Steps of the DALK Surgery

After disinfecting the eye and its surroundings under local or general anesthesia, it is covered with a sterile cloth.

The upper layer of the cornea is removed with the "Big Bubble" technique or by manual lamellar dissection in a circular area with a diameter of 7-7.5 mm in the center of the cornea.

The upper layer of the previously prepared donor cornea is prepared in accordance with the recipient area in the center of the cornea and sutured to the recipient area.

At the end of the operation there are at least 16 stitches in the eye.

The procedure is ended by applying an antibiotic drug to the eye.

The duration of the operation is approximately 40-50 minutes. If there are other interventions to be performed at the same time, the duration of the operation may prolonged.

What should be considered after the DALK Surgery?

There may be complaints such as stinging and watering in the eyes for a few weeks after the surgery. A protective bandage is used on the day of surgery. The level of vision may not immediately increase much. Postoperative antibiotic and cortisone eye drops are used in accordance with the physician's recommendation.

The first control is performed on the first day after the operation and the control frequencies are adjusted according to the condition of the transplanted tissue. Stitches are usually removed after 6 months.

Features of the DALK

In DALK surgery, patients preserve the endothelial cells, which form the innermost layer of the cornea. Since the endothelial cells of the donor tissue are not removed, the risk of corneal rejection is dramatically reduced. Thus, the duration of using cortisone drops is shortened. Wound healing is faster and stitches are removed in about 6 months.

DMEK (Descemet's Membrane Endothelial Keratoplasty)

The process of replacing only the bottom layer of the cornea, not the full layer, is called DMEK. It is most commonly performed in bullous keratopathy (permanent corneal edema). Permanent corneal edema can be seen after a certain age in hereditary corneal diseases or sometimes after cataract surgeries.

Steps of the DMEK Surgery

After disinfecting the eye and its surroundings under local or general anesthesia, it is covered with a sterile cloth.

The lowest layer (endothelium) of the cornea is peeled off.

The pre-prepared donor corneal endothelium is transplanted into the recipient.

1-2 stitches are placed on the wound site.

Air is pumped into the eye to facilitate the attachment of the donor tissue. This air is gradually withdrawn within 1 week.

The procedure is ended by applying an antibiotic drug to the eye.

The duration of the operation is approximately 40-50 minutes. If there are other interventions to be performed at the same time, the duration of the operation may be extended.

What should be considered after the DMEK Surgery?

Complaints such as stinging and watering may occur very rarely for a few weeks after the surgery. A protective bandage is used on the day of surgery.

The level of vision may not immediately increase much. Postoperative antibiotic and cortisone eye drops are used in accordance with the physician's recommendation. The first control is performed on the first day after the operation and the control frequencies are adjusted according to the condition of the transplanted tissue.

Features of DMEK Surgery

In DMEK surgery, patients preserve the upper layers of their corneas. Therefore, the cornea becomes more resistant to trauma.

Postoperative refractive errors such as myopia, hyperopia and astigmatism are less common. There are not many stitches as in other corneal transplants.