Corneal transplantation (keratoplasty)

Corneal transplantation, in medical terminology keratoplasty, is an important procedure for the treatment of corneal diseases. During surgery, the patient's damaged cornea is replaced with a donor cornea. In this way, we can treat even irreversible damage to the cornea and successfully restore lost vision in many cases.

In our eye clinic we will be happy to advise you personally on the subject of corneal transplantation and on all questions concerning the cornea. If keratoplasty is necessary for you, we will inform and prepare you in detail before the operation. As a rule, corneal transplantation takes place on an inpatient basis, so that you receive comprehensive medical care after the operation.

The cornea at a glance

In the human eye, the cornea fulfills several important functions. It forms the outer, clear layer of the eye and is thus responsible for ensuring that incident light rays reach the retina unhindered. Through its curvature, the cornea also ensures the correct refraction of light and thus sharp perception. Last but not least, it also protects the interior of the eye and gives the eyeball its round shape.

The cornea consists of several layers, which can be altered in their shape and structure for various reasons. Injuries, inflammations and diseases and can result in scarring or clouding of the cornea. Depending on which cell layer is affected, vision may be limited or even lost. In such cases, a corneal transplant is usually the only way to restore corneal function.

What is a corneal transplant?

Corneal transplantation is the oldest and most frequently performed form of tissue transplantation. In Germany, about 9,000 corneal transplants take place every year. In comparison, kidney transplantation, the most common form of organ transplantation, is performed about 2,000 times per year. Accordingly, corneal transplantation is nowadays a routine procedure, the technical performance of which is constantly being developed and improved.

During transplantation, we replace the damaged part of the cornea with healthy donor corneal tissue. In this way, scarring, injuries or changes in the shape of the cornea can be corrected. Thanks to technical advances, the success rate is nowadays high, especially compared to organ transplantation. Rejection reactions are much less common with corneal transplants.

When is a corneal transplant necessary?

A transplantation may be necessary if irreversible changes of the cornea occur and the patient's vision is considerably limited as a result. For example, we perform keratoplasty in cases of inflammation and injury to the cornea, when scarring or clouding of the cornea has occurred. Corneal scars can also be the result of ulcers or infections.

Furthermore, degenerative diseases can lead to thinning and deformation of the cornea (e.g. keratoconus). Here, too, we usually achieve very good results with corneal transplantation.

What are the methods of corneal transplantation?

Two different surgical methods are used, depending on the type and extent of the corneal alteration. We distinguish between penetrating and lamellar keratoplasty. Penetrating keratoplasty is the classic procedure in which the eye is completely opened, while lamellar keratoplasty leaves part of the cornea intact. We decide which surgical method is suitable in each individual case based on the individual findings.

Perforating keratoplasty

In this classic procedure, a disc 7-8 mm in diameter is removed from the opaque cornea with a circular knife. The disc covers the entire thickness of the cornea. In parallel, a disc of the same size is punched out of the healthy donor cornea and transplanted into the recipient's eye.

Lamellar keratoplasty

In this surgical method, we only replace the damaged corneal layer with appropriately cut donor tissue. Depending on the type of disease, anterior lamellar keratoplasty can be performed in the anterior part of the cornea, for example to replace superficial scars or unstable anterior parts of the cornea. In posterior lamellar keratoplasty, on the other hand, we replace the diseased inner layer of the cornea with healthy donor tissue.

Since part of the patient's cornea is preserved, healing usually progresses much faster after lamellar keratoplasty. The risk of rejection and other complications is also significantly reduced.

What happens before a corneal transplantation?

As a rule, a transplantation is not necessary suddenly, but only after a longer period of ophthalmological treatment. In the course of this treatment, numerous examinations already take place, so that we can precisely assess the condition of your cornea. Your attending ophthalmologist will make the decision for surgery together with you and inform you about all details of the procedure.

As soon as the decision for a corneal transplantation has been made, a suitable transplant has to be found. This is done through a so-called cornea bank. Since there are fewer transplants than recipients, waiting times of 3-6 months on average must be expected.

The operation usually takes place under local anesthesia, but sometimes a general anesthesia is useful. In advance, a medical clarification by the general practitioner is necessary. Anticoagulant medications should be discontinued before the operation if possible, but always only in consultation with the prescribing physician.

What is the procedure of corneal transplantation?

The keratoplasty itself usually takes a maximum of one hour. Using a circular knife, the surgeon removes a 7-8 mm disc from the central part of the cornea. A disc of the same size is removed from the donor cornea and sewn into the recipient's eye. For this purpose, the surgeon uses a surgical microscope, which allows him to proceed with absolute precision. The eye is anesthetized during the operation and therefore motionless.

What is the healing process after corneal transplantation?

After the transplantation, patients remain as inpatients in our clinic and receive comprehensive medical care. Strict bed rest is usually not required. However, you should remain in a supine position for the first 24 hours and avoid any pressure or rubbing of the eyes.

After the operation, a bandage will be applied, which can usually be removed the following day during the first follow-up examination. After a corneal transplant, the eyes usually have to be treated with eye drops for many months. You should absolutely adhere to this as prescribed by your doctor in order not to endanger the success of the operation.

The sutures remain in the eye for several months, as the cornea needs some time to grow firmly. The ophthalmologist determines the time of suture removal for each patient individually. Only after this can it be judged whether the corneal transplantation was successful.

Vision is initially still limited after corneal transplantation. It often takes many weeks and months until vision is fully restored. During this time, visual acuity may also still fluctuate. In the course of healing, the ophthalmologist will determine with you when is the right time to fit new lenses, at least temporarily.

Can a rejection reaction occur?

Rejection reactions are rarer in corneal transplantation than in other forms of tissue transplantation. Nevertheless, rejection of the foreign tissue can never be completely ruled out. Then the body perceives the transplant as a foreign body and fights it via the immune system. Such a rejection reaction usually becomes apparent within the first five years after the operation, but can also occur at a later stage.

Symptoms of graft rejection include reddened or watery eyes, increased sensitivity to light or touch, and sudden deterioration of vision. If you experience these or similar symptoms after a corneal transplant, you should see your eye doctor as soon as possible. Early treatment can usually successfully avert further complications.

What are the other risks of corneal transplantation?

In general, the risks of keratoplasty are relatively low. There is a risk of reoccurrence of opacities and the need for another transplantation. Also, some patients are left with a corneal curvature that cannot always be satisfactorily corrected with glasses or contact lenses. In such cases, corrective surgery or laser treatment may be appropriate.

As with all surgical procedures, complications can occur in individual cases, for example infection, bleeding or injury to structures in the eye.

Even with a clearly ingrown cornea, there remains a certain residual risk of complications with the implant throughout the patient's life.

What effect will a corneal transplant have on my vision?

After a corneal transplant, you should be prepared for a healing period of several months, during which there may be major fluctuations in vision. Any existing opacities or scarring of the cornea will be completely removed during the course of the transplant, so that vision will be unclouded after successful healing. However, most patients continue to require glasses or contact lenses after keratoplasty.

How is the required donor cornea obtained?

Corneal transplants come exclusively from deceased people. As with organ donations, legal regulations apply to the harvesting process. Only if the brain death was determined by two physicians beyond doubt and the donor agreed to a tissue removal during his lifetime, a transplantation may take place. The allocation takes place via a central cornea bank.

Prior to transplantation, it is verified that the cornea is functional and that the donor did not suffer from an infectious disease. However, an existing visual impairment or other eye diseases of the donor are not an obstacle, nor is old age. Also the blood group does not play a role for a corneal transplantation as a rule.

How long is the waiting time for a corneal transplant?

On average, patients have to wait about 3-6 months for a corneal transplant. This is because there are still fewer donor corneas than recipients. Also, there is always the possibility that the transplantation has to be postponed at short notice because the transplant is not suitable after all.

What are the costs for a corneal transplant?

The costs for a keratoplasty are covered by health insurance, since it is usually a necessary medical intervention. Additional costs may be incurred if the patient decides to undergo surgery with a modern laser procedure (femtosecond laser). In this case, the difference is not covered by the statutory health insurance.

Before the corneal transplantation, we will explain to you exactly which treatment procedure makes sense from the medical point of view and whether additional costs would be incurred for this. The decision for a keratoplasty or a certain treatment method is always made together with the patient.