Corneal transplantation or keratoplasty is an operation to replace part of the cornea with healthy corneal tissue from a donor.
The cornea is the curved transparent surface of the eye, which is indispensable for focusing the images.
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Types of corneal transplantation
The cornea has five layers.
Corneal grafts do not always replace all layers.
Types of corneal transplantation include:
Perforating keratoplasty (in full strength). This procedure replaces all corneal layers.
Lamellar anterior or posterior keratoplasty. In this procedure, the surgeon replaces only a few layers in the anterior or posterior area of the cornea.
With lamellar keratoplasty, only the damaged layer can be transplanted.
Selective transplantation of diseased tissue can affect the following layers:
- Only the deeper layer, the so-called endothelium (posterior lamellar keratoplasty or endothelial transplantation of the cornea). This procedure is called DSAEK.
- Only the layers near the surface (anterior lamellar keratoplasty), in this case the procedure is called DALK.
New methods and technologies for corneal transplantation
New developments in corneal transplantation surgery include stem cells, femtosecond lasers and biosynthetic corneal transplants.
- Stem cell transplantation
Stem cell research helps determine the best type of cell to transplant, the best method for transferring the cultured cells to the surface of the eye, and measures to reduce the risk of rejection through immunosuppressive therapy.
Candidates for this type of transplant had a deep and irreversible lesion of the cornea, for example, as a result of burning, infection or prolonged use of contact lenses.
- Femtosecond laser
The femtosecond laser is increasingly used for the preparation of recipient tissue, especially for lamellar dissection.
The femtosecond laser allows the surgeon to cut the cornea of the donor and recipient in a precise manner at a depth that allows selective transplantation. - Transplantation of artificial cornea The transplantation of an artificial cornea is a possibility for patients who are not candidates for a traditional corneal transplant or for whom a corneal
transplant has not been successful (rejection of the graft).
When is a corneal transplant useful?
A healthy and clear cornea is the prerequisite for good vision.
If the cornea is damaged due to eye disease or eye injury, it can:
- swell
- have scratches,
- be severely deformed.
As a result, vision is impaired.
A corneal transplant may be needed to restore the anatomy or clarity of the cornea and thus improve vision when glasses or contact lenses are no longer able to do so.
Certain diseases can affect corneal clarity and endanger corneal tissue.
Indications are:
- Fibrosis and leucomas caused by infections such as herpes on the eye or fungal keratitis.
- Structural changes: congenital diseases such as fox dystrophy (associated with bullous keratopathy)
- Changes in curvature: diseasessuch as advanced keratoconus.
- Changes in thickness: thinning of the cornea.
- Consequences of surgery: Rare complications caused by laser surgery type LASIK.
- Graft rejection after previous corneal transplantation.
- Weakening of the cornea due to complications after cataract surgery.
- Chemical burns of the cornea or damage caused by eye injuries.
Before the procedure
It may be necessary to limit the use of anticoagulants 10 days before the procedure.
These include, but are not limited to:
- Aspirin
- Ibuprofen (Dolormin Extra),
- Coumadin®.
You can take other medication on the morning of the day of the operation, but you should talk to your doctor about it first.
It is necessary to inform the doctor about the use of the following medicines:
- Diuretics
- Insulin in diabetes.
To prepare for surgery, make sure that there are no diseases or infections of the eyes or other areas of the body that would increase the risk of complications.
On the morning of the procedure, the patient must be fasting:
- After midnight you are not allowed to eat or drink too much fluid.
- You can drink water up to 2 hours before the operation.
- Do not drink alcohol 24 hours before or after the operation.
Note: These are general guidelines. The surgeon may have special requirements.
How is corneal transplantation performed at full strength?
The procedure can be performed under local anesthesia.
For this, a drug is used for anesthesia and immobilization of the eye.
The patient remains awake but is sedated during surgery.
Another option is general anesthesia.
The surgeon uses a special instrument called a trepan to cut out the cornea. The surgeon removes a round part of the damaged cornea from the front of the eye.
The same procedure is used to cut a circle of similar size from the donor’s cornea.
The surgeon inserts the new corneal part into the eye. Then he sews it under the microscope with ultrafine sutures.
How long does the transplant take?
The procedure takes about 1.5 hours.
After corneal transplantation
Many people need to stay in the hospital for a day or two after a corneal transplant.
The eye may be covered by a bandage that is removed the day after surgery.
Immediately after surgery, some symptoms may appear, which gradually disappear over the course of a few days; These include:
- Redness, burning, pain and discomfort in the operated eye
- Foreign body sensation
- Glare
- Photophobia
- Flying mosquitoes in view
- Halos
- Blurred vision
If a transplant of limited strength is performed, which uses an air bubble instead of a suture to fix the graft in position (endothelial keratoplasty), it may be necessary to lie on your back for the first day or two after surgery. This serves to keep the cornea in its proper position.
The bladder is absorbed after a few days.
When is the suture removed?
The seam can remain for several years if it does not cause any problems. Normally, it is not removed until at least a year has passed since the procedure. In this way, postoperative astigmatism can be controlled, which can be clearly pronounced and varies during recovery.
What can and cannot be done after the transplant
If you have returned home after the operation, you should be considerate of your eyes.
Normal day-to-day activities may be carried out, such as:
- Read
- Television
- Execution of light housework.
Some important points to keep in mind:
- Avoid pressing or rubbing on the eyes.
- During the first postoperative week, avoid intense physical activity and lifting heavy loads.
- If the work activity is not particularly physically demanding, you can return to work two or three weeks after the transplant.
- If the profession involves heavy physical work, three to four months should pass after the operation.
- Smoky and dusty environments should be avoided, they could irritate the eyes.
- If the eye is sensitive to light, sunglasses can help.
- Do not engage in contact sports and do not go swimming until the ophthalmologist gives permission.
- If you do sports again, you should wear safety glasses.
- Bath and shower can be done normally, but you should not wet the eye with water for a month.
- Do not drive until the specialist gives permission.
Pregnancy and breastfeeding – A woman who becomes pregnant within the first year after a corneal transplant can give birth normally.
In the case of injuries to the retina, on the other hand, the doctor could advise a caesarean section.
Convalescence after corneal transplantation
As a rule, you have to wear plastic protection at night in the first few weeks after surgery to protect the eye.
With all types of corneal transplantation, it is necessary to strictly adhere to the therapy prescribed by the ophthalmologist; this usually means:
- taking corticosteroids,
- daily use of antibiotic eye drops.
These drugs are usually prescribed for a few months, some people even need them for more than a year.
The drops reduce swelling and inflammation and prevent infection and rejection.
Testimonial of a patient
Thorough transplantation of a donor cornea due to keratoconus
The first examination took place in September 2010, I was 18 years old at the time. The doctors did check-ups
to make sure I could get through these surgeries.
Since there were no contraindications, I was put on the transplant list.
After 12 months, I was contacted because they had found a suitable cornea.
Since I was young, it was difficult to find an equally young cornea.
The younger the cornea, the better the vision.
- I was taken to the hospital and given general anesthesia.
- The procedure took about 1.5 hours.
- After waking up, I had no particular complaints, but I took a painkiller for 3 days.
- After 3 days I was back home.
- In the first week, the eye had to remain bandaged, I could not reveal it, the light caused discomfort.
- After 1 week I had to go to the hospital for a check-up.
The eyesight was immediately back.
After a year, it has stabilized better.
After the transplant, I go to the doctor’s check-up every 6 months.
Risks of corneal transplantation
Corneal transplantation is a relatively safe operation.
Possible complications include:
- Infections
- complaints caused by the suture material used,
- increasing the risk of cataracts (clouding of the lens),
- increased eye pressure (glaucoma),
- Rejection reaction
- severe refractive error (astigmatism, myopia, or both).
When does rejection occur?
The risk of rejection begins after about a month and decreases after one year.
Most episodes of rejection occur in the first year after transplantation, but sometimes rejection can take many years.
If the patient has suffered from a viral infection in the past or had other eye infections that led to the transplant, the eye drops used for the eyes must be checked with the surgeon.
What are the signs of rejection?
- Redness: rejection can lead to eye redness.
- Sensitivity: it can cause greater sensitivity to light.
- Vision: it can lead to vision loss or blurred vision.
- Pain: it can cause discomfort, irritation or a foreign body sensation.
You should contact your doctor immediately if any of these possible signs of rejection occur.
Vision
restoration The time required to restore vision after a corneal transplant depends on the procedure performed.
In some cases, vision may fluctuate between improvement or deterioration before stabilization.
Recovery times for the most common types of corneal transplantation are:
- perforating keratoplasty – within 10-12 months;
- anterior lamellar keratoplasty – a few weeks;
- deep anterior lamellar keratoplasty (DALK) – up to twelve months;
- endothelial keratoplasty Descemet (DSEK) – about four to eight weeks.
Probably a defect of myopia and astigmatism remains, because the new corneal curvature does not correspond exactly to the curvature of the natural cornea.
Postoperative refraction is unfortunately quite unpredictable.
Slight refractive errors caused by corneal transplantation surgery can be corrected by glasses, in some cases use contact lenses.
Rigid gas permeable contact lenses or hybrid contact lenses are best suited for corneal transplant patients who have a corneal irregularity due to transplantation.
Since vision changes in the first few months after the transplant, it is advisable to wait for permission from the ophthalmologist before wearing glasses or contact lenses.
After the eye is completely healed, LASIK or PRK surgery may be considered to improve vision or improve myopia and astigmatism.
Corneal Transplant Success Rate
Success rates vary depending on the problem that should be solved by the transplant.
For example, science has found that the new cornea lasts for at least 10 years in the following cases:
- > 90% of patients with keratoconus, corneal scars and bullous keratopathy in the initial stages;
- 80-90% of patients with fox dystrophy and advanced bullous keratopathy;
- 50% due to corneal infections;
- 0-50% due to chemical lesions, abrasions or ulcers of the cornea.
