Corneal transplant consists of the total or partial replacement of the damaged cornea with a healthy cornea. This procedure is called keratoplasty.

This surgical procedure is indicated in cases of loss of transparency of the cornea, deformations in its format, perforations or in the presence of scars that make vision difficult.

The cornea is a transparent structure, without blood vessels, located in the anterior part of the eyeball and composed of several layers with different functions.

The cornea is considered healthy when its structure does not present opacities, has a normal thickness, and has a normal curvature, allowing images to be sharply focused on the retina. To guarantee a good quality of vision, it is fundamental that the cornea maintains its transparency and integrity. When it presents irreversible lesions, a cornea transplant may be recommended.

According to data from the National Health Service, around 900 corneal transplant operations are carried out every year in Portugal.

In order to perform a corneal transplant, it is necessary to have a cornea donated through a tissue bank and which can be applied to the patient to be operated on.

The surgical technique chosen should take into consideration the reason for the corneal transplant and which corneal layers, being involved in the disease, need to be transplanted. When all corneal layers are transplanted, this is a penetrating keratoplasty. When only some layers of the cornea are transplanted, the procedure is called lamellar keratoplasty. Lamellar keratoplasty can be divided into posterior, when it involves the deeper layers of the cornea, and anterior, when it involves the more superficial layers.

While alternatives are often available in early stages of disease, corneal transplantation is typically performed in more advanced stages and/or in severe forms of corneal diseases such as keratoconusCorneal transplantation can also be performed in other corneal degenerative diseases, corneal dystrophies such as Fuchs' dystrophy, scars of different origins, chemical burns, or traumatic injuries.

The duration of a corneal transplant, depends on the surgical technique chosen. On average, a penetrating keratoplasty or anterior lamellar keratoplasty lasts between 45 and 60 minutes, while a posterior lamellar keratoplasty lasts about 20 to 30 minutes.

The anaesthesia used in this type of surgery may be local, general anaesthesia or sedation, being decided on a case-by-case basis.

Corneal transplantation is a relatively frequent surgery with a high success rate.

As with other transplants there is a risk of rejection, this happens because the immune system recognises the new tissue as an external agent and therefore tends to react against it. The risk of rejection in corneal transplantation is around 1.9% to 20%, depending on the technique used and it can occur during the first years after the transplant.

Apart from the risk of rejection, lamellar transplant detachment may occur. Associated with corneal transplant surgery are the same risks as any other intraocular surgery, such as infections, macular oedema cataract secondary, glaucoma secondary or detachment from retina detachmentamong others.

Recovery after corneal transplantation is gradual and may be different depending on the type of technique used. Generally, lamellar transplants provide a faster recovery, better visual acuity and a lower risk of infection or rejection.

The appearance of refractive errors such as astigmatism is common after corneal transplant, which can reach an average of 4 dioptres (in the case of penetrating transplants) one year after surgery. In order to reduce astigmatismthe stitches are removed gradually and usually a few months after surgery, depending on the technique used.

As it is an important surgery in which the patient's collaboration is essential, it is recommended that the doctor's instructions are always followed and that the patient attends all the follow-up consultations.