Cornea transplant
Corneal transplant is a surgical intervention whose objective is to replace an opacified or diseased cornea with another in good condition, to regain vision or prevent the possible inflammation or infection of the cornea from passing into the eye.
To carry out the cornea transplant we have different techniques, depending on the origin of the problem of the cornea or its anatomical state. When the cornea has all its layers altered or before a perforation, it is necessary to transplant all the layers, it is what we know as Transplant or Penetrating Keratoplasty. When the damage affects only part of the layers of the cornea, a Transplant or Selective Keratoplasty, only from the damaged layers.
Currently, in most cases, we perform selective transplantation since it is less traumaticHas less complications, graft viability is prolonged and visual recovery is faster.
Cornea transplant
Corneal transplant is a surgical intervention whose objective is to replace an opacified or diseased cornea with another in good condition, to regain vision or prevent the possible inflammation or infection of the cornea from passing into the eye.
To carry out the cornea transplant we have different techniques, depending on the origin of the problem of the cornea or its anatomical state. When the cornea has all its layers altered or before a perforation, it is necessary to transplant all the layers, it is what we know as Transplant or Penetrating Keratoplasty. When the damage affects only part of the layers of the cornea, a Transplant or Selective Keratoplasty, only from the damaged layers.
Currently, in most cases, we perform selective transplantation since it is less traumaticHas less complications, graft viability is prolonged and visual recovery is faster.
What is corneal transplant?
Corneal transplant it is a surgery that is performed when the cornea loses its transparency and does not let light pass into the retina. The consequence is loss of vision.
Our most frequent causes of loss of transparency of the cornea are:
- corneal infections (Herpetic keratitis, ulcers bacterial or fungal).
- Corneal degenerationsand Keratoconus or endothelial degeneration after cataract surgery.
- Corneal dystrophies, most hereditary transmission, such as Fuchs' endothelial or granular or lattice dystrophies.
- Trauma facial with corneal involvement or chemical caustications by acids or legia.
In these cases we know that the corneal tissues lose its laminar structure and with it, the transparency irreversibly. The The only possible treatment will be to replace that diseased cornea with a corneal transplant, also called keratoplasty.
El cornea transplant (keratoplasty), is the most successful of tissue transplants. The average success rate depends on the cause that caused the loss of transparency of the cornea. For example, corneal transplants by degeneration secondary to cataract intervention, y those due to keratoconus, are the ones that have higher success rate. However, transplants secondary to chemical causticizations or immunological processes, have worse results.
When should a corneal transplant be done?
The indication to perform a cornea transplant is due to 2 main reasons:
- La irreversible vision loss by corneal diseases that cause their opacification.
- El risk of not preserving the anatomical structure of the eye, that is, situations of corneal perforation or infections of the cornea that can spread to the interior of the eye.
Among the main corneal transplant causes we find the bacterial infections, fungal o viral are frequent causes of ulcerations y severe corneal abnormalities. Alterations of corneal curvature (keratoconus), degenerations that may appear after cataract surgery (corneal edema or swelling), and some degenerative processes, can affect corneal transparency.
Some corneal diseases They are hereditary, and can cause blurred vision and loss of vision and with it, cause the need for a cornea transplant.
Types of cornea transplant
Among the various types of corneal transplant we find two:
Penetrating cornea transplant
The cornea It is in the most anterior area of the eye and is characterized by being transparent, to let light pass into the retina, where the visual process will start.
When a lesion on the cornea that breaks down all the layers that make it up, transparency will be irreversibly lost. It is in these cases when it is necessary to indicate a transplant of the entire thickness of the cornea, “penetrating transplant", generally with a diameter between 8 and 8.5 mm. Less than the diameter of the receiving cornea (that of the patient), around 12 mm in diameter. In fact, the donor cornea is spliced with the patient's cornea ring that we leave behind to be able to suture it.
La advantage of this surgery is that it is usually the only option in severe cases of corneal pathology. The main disadvantage is that the recovery is slower and more complex there is more risk of rejection immunological
Lamellar cornea transplant
It consists of a selective corneal transplant where we transplant only the layer of the cornea that is damaged. There are 2 types of lamellar transplant: the front and the back.
Lamellar anterior
The anterior lamellar cornea transplant is the surgical technique we use to transplant the previous layers of the cornea and depending on the depth at which the lesions are found in the cornea, we divide it into 2 basic techniques:
- Superficial anterior lemellar (SALK)
- Deep anterior lamellar (DALK)
Posterior lamellar or endothelial
In the posterior lamellar transplant or endothelial transplant, we substitute the deeper or posterior layers of the cornea, the endothelium and/or Descemet's.
Our surgical techniques for posterior lamellar or endothelial cornea transplantation are:
How is the corneal transplant operation?
The corneal transplant tissue comes from an eye bank. The process begins with the request of a cornea to be transplanted. The eye bank is notified and if there is a donation due to the death of a donor, the surgical intervention can be arranged. The operation consists of implanting the central and transparent part of the cornea donor, usually 8 to 8.5 mm in diameter, in the patient's eye.
Currently, you can select part of cornea donor what we want to transplant, Is not always all cornea (penetrating transplant), sometimes only such a part is necessary, if we have a patient who has suffered a viral corneal affectation that left a scar in the most anterior layers of the cornea, it will suffice to replace, with transplant, Those damaged layers, respecting the rest of the cornea, is what we call lamellar transplant. In the same way, corneal diseases that only affect the corneal endothelium, the innermost layer of the cornea, can be cured by doing a selective transplant of this layer, it is the endothelial transplant.
In all the types of transplantation that we have described above, the corneal tissue to be transplanted must be prepared, as well as the recipient cornea, that of the patient. In a penetrant transplant, you have to carve the graft diameter (8 / 8.5 mm), with a trephine that cuts it precisely. In the same way, you have to carve the "window" of the patient's cornea, with a trephine and preserving a ring of cornea in which the graft is sutured. The carving is similar in diameter to that of the graft or somewhat larger, 0.5 mm. The donor cornea is sutured with the patient's cornea ring, with a very fine nylon thread, using loose stitches, continuous suture or a combination of both.
When it comes to a selective transplant, the layers of donor cornea must be dissected to replace the damaged cornea of the patient. They are very delicate maneuvers that are performed with microkeratomes. This dissection is complex and requires highly experienced surgeons since the tissue to be transplanted can easily be damaged, causing the surgery to fail.
In rural areas of India, families in charge of a blind minor frequently isolate and deprive him/her of the care and attention they provide to their other children; such situation becomes even more severe among lower-caste families, orphans and if the blind child is a girl. previous keratoplasties, it is necessary to suture the graft on the recipient cornea, while in the posterior lamellars, we introduce the graft in the eye and it is fixed in the correct position without the need for suture. It is a very delicate process and requires the skill of the surgeon. The great advantage is that the recovery is much faster than penetrating keratoplasties.
El selective transplant presents many and advantages as retains part of the patient's cornea, which allows improve results and a faster recovery. The only problem is that requires a very skilled surgeon and more sophisticated technology and that makes the process more expensive and not all ophthalmologists have it.
This surgery is usually done in the form ambulatory, with Anesthesia local y sedationso that the patient can return home the same day of the intervention.
Corneal transplant postoperative
La vision recovery after corneal transplantation it may take a while. Generally recovers from a 20% to 30%, in the first days and the rest depends a lot on the disease causing corneal opacification or the technique performed, and may need up to one year after surgery. In general, you have to have careful with physical exercise and activities that require visual effort. Usually we do not cover our eyes and although the recovery is progressive, after the first week already activities can be carried out allow the patient to be self-sufficient.
As in the rest of the transplants, the donor tissue can be rejected, especially when the endothelium is transplanted, both in penetrating keratoplasties and in posterior lamellar ones (DMEK and DASEK). The major signs of rejection They are a eye redness, pain y worsening vision. If this happens, it must be go quickly to the ophthalmologist, even though several years have passed after the surgery.
Cornea transplant in Área Oftalmológica Avanzada
Until recently, in most cases the penetrating cornea transplant, of all its layers, very aggressive, with a higher risk of failure and with a long recovery time. For this reason, currently developed lamellar transplant techniques, only from the altered layers, which reduces risk and recovery time.
En Our center has been pioneers in modern lamellar techniques, participating in the design of sophisticated instruments for its realization, such as the Moria ™ Microkeratome for Anterior Lamellar Transplantation and Endothelial Transplantation or DSAEK-DMEK.
On many occasions we find the condition of the cornea and the ocular surface, very deteriorated and it is necessary to perform a previous reconstruction surgery. Treatments must be carried out to regenerate the ocular surface and prepare the ground for ensure that corneal transplantation is effective and safe. These regeneration maneuvers consist of the amniotic membrane implant, limbo transplant o cell culture implants and stem cells. They are very sophisticated techniques that require de highly experienced surgeons, such as Dr. Vergés, one of the first ophthalmologists in Europe to perform this type of treatment and means that are only available in large hospitals or highly specialized centers, like in our case that in Dexeus University Hospital, we have all this technology and specialized personnel to carry out these techniques. There are many patients, national and international, who come to our center and who have benefited from these advances that have been able to recover their vision.
FAQ
What is the cornea?
The cornea is a tissue that is in the most anterior area of the eye and is characterized by being transparent, to let light pass into the retina, where the visual process will start.
Our corneal diseases that directly or indirectly affect its transparency, will cause a interference with the passage of light into the eye, the result end one loss of vision.
What can damage the cornea?
Knives, pencils and other sharp objects can cause serious corneal injuries. Fireworks, battery explosions y Chemicals toxic, especially alkaline and legia, can also cause severe scarring of the cornea.
In fact, corneal involvement is the first cause of ophthalmological emergency. When the injury is due to a chemical product, necessary wash the eye with water or physiological serum abundantly. Many corneal injuries can be prevented with the use of protective goggles and taking precautions when handling hazardous substances.
Diseases that damage and cloud the cornea
Various diseases can cause damage that causes loss of transparency of the cornea, irreversibly and which makes it necessary to perform a cornea transplant to regain vision.
The most frequent diseases are herpetic virus corneal infections, ulcers bacterial or fungal, immune diseases of the skin such as Pemphigoid, or in cases of ulcers due to rheumatism or other collagen diseases, like Lupus or dry eye by Sjögren.
Why is the cornea rejected?
The rejection is due to the immune recognition mechanisms detect that the transplanted corneal graft does not belong to the host tissues, of the person to whom the transplant has been performed. They do not recognize it as their own and initiate a defense reaction aimed at eliminating that tissue, as if it were an invasive microorganism.
We know that in the cornea, The layer with the greatest immunological load is the endothelium.. For this reason we try to preserve the patient's endothelium for avoid rejection. In previous lamellar keratoplasties, we always try to maintain the patient's endothelium, and current techniques allow all layers to be dissected, down to the barely 20-micron endothelium, and replace everything else. With this surgery, we managed to reduce the rejection of the transplant and that the grafts exceed 10-15 years of survival, compared to 5-10 before.
