Cornea Transplant

What is a cornea transplant?

The transparent layer in front of the iris, 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 takes place.

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 cornea dystrophy, cornea 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 cornea tissue. In this transplant process, the tissue is healthy cornea tissue taken from a deceased person and the process is called cornea transplant.

Cornea transplantation can be done with full-thickness cornea 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 cornea transplants are more successful than other transplants is due to this feature.

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What are the steps of full thickness cornea transplantation (penetrating keratoplasty) surgery?
  • After disinfecting the eye and its surroundings under local or general anesthesia, it is covered with a sterile drape.
  • 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 bed with another vacuum tool (punch) containing a circular blade.
  • The donor cornea is sutured to the recipient bed with different suture techniques (16 single stitches, 16 single stitches with continuous stitches, continuous double stitches, etc.).
  • The procedure is terminated 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 be prolonged.

What to expect after Full Thickness Cornea Transplant?

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 performed every month during the 1st week and the first 1 year. Stitches are usually removed after 1 year.

What are the complications that can be seen during a full-thickness cornea transplant surgery?

Expulsive bleeding: It is a bleeding that is difficult to control due to the accumulation of blood in the choroid, which is the vascular tissue of the eye. This situation is very rare (0.45-1.08%). It is not possible to predict in advance and if it happens it can result in loss of the eye.

Astigmatism: Astigmatism is common after cornea transplantation. Stitches placed with tissue healing change these astigmatism values ​​over time. Astigmatism can be removed with suture removal, re-stitching, loosening incisions or LASIK.

Increased intraocular pressure (glaucoma): It can be seen in the early or late period. The increase in intraocular pressure seen in the early period is quickly controlled with drugs. The increase in intraocular pressure seen in the late period is usually due to the cortisone drops used. In this case, it is necessary to use drugs that reduce intraocular pressure.

Infection: Serious infections can be seen after intraocular surgeries, albeit very rarely. It is an important condition and requires early intervention.

Tissue rejection: It can be seen especially in patients with vascularization in the cornea for other reasons. In such cases, some special needles are applied to the eye and the rejection of the tissue is tried to be prevented with drops and drugs.

Femtosecond Laser in Full Thickness Cornea Transplant Surgery

In full-thickness cornea transplantation, instead of a vacuum instrument (trepane) containing a round blade used in the preparation of the recipient bed, 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. Wound compliance is very smooth in corneas prepared with femtosecond laser.

DALCT (Upper Layer of the Cornea Transplantation)

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

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

What are the steps of DALCT surgery?

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

The upper layer of the cornea, 7-7.5 mm in the center of the cornea. diameter circular area with the “Big Bubble” technique or by manual lamella dissection.

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

There are at least 16 stitches in the eye.

The procedure is terminated 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 prolonged.

What to expect after DALCT 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.

What complications that may occur during DALCT surgery?

Loss of integrity in the lower layer of the cornea: This may sometimes prevent the operation from continuing as DALCT and full-thickness cornea transplantation can be started.

Astigmatism: Astigmatism is common after cornea transplantation. Stitches placed with tissue healing change these astigmatism values ​​over time. Astigmatism can be removed with suture removal, re-stitching, loosening incisions or LASIK.

Increased intraocular pressure (glaucoma): It can be seen in the early or late period. The increase in intraocular pressure seen in the early period is quickly controlled with drugs. The increase in intraocular pressure seen in the late period is usually due to the cortisone drops used. In this case, it is necessary to use drugs that reduce intraocular pressure.

Infection: Serious infections can be seen after intraocular surgeries, albeit very rarely. It is an important condition and requires early intervention.

Tissue rejection: Since the endothelial cells, which form the innermost layer of the recipient cornea, are preserved, the risk of rejection is very low.

What are the features of DALCT?

In DALCT 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 cornea rejection is dramatically reduced. Thus, the duration of using cortisone drops is also shortened. Wound healing is faster and stitches are removed in about 6 months.

What is LLCT (Lower Layer Transplantation of the Cornea)?

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

What are the stages of LLCT Surgery
  • After disinfecting the eye and its surroundings under local or general anesthesia, it is covered with a sterile drape.
  • 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 introduced into the eye to facilitate the attachment of the donor tissue. This air is gradually withdrawn within 1 week.
  • The procedure is terminated 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 prolonged.

What to expect after LLCT 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.

What may be the complications after LLCT surgery?

Inability of the lower layer of the cornea to adhere to the recipient bed: Air is introduced into the eye to prevent this situation. In case of failure to hold on for a long time, re-intervention may be required.

Increased intraocular pressure (glaucoma): It can be seen in the early or late period. The increase in intraocular pressure seen in the early period may be related to the air given into the eye, and it is quickly controlled with drugs. The increase in intraocular pressure seen in the late period is usually due to the cortisone drops used. In this case, it is necessary to use drugs that reduce intraocular pressure.

Infection: Serious infections can be seen after intraocular surgeries, albeit very rarely. It is an important condition and requires early intervention.

Tissue rejection: In this case, some drugs are used to prevent tissue rejection.

What are the features of LLCT Surgery?

In LLCT 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.

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