The cornea is a transparent layer in the front of the eye positioned just opposite the iris, the " colored part of the eye". In fact, the eye color is related to the iris which varies randomly from person to person. But the cornea is completely transparent like a window and allows the light to enter the eye. The cornea also refracts the light so that images of near and far objects will be focused on the retina. Corneal transplantation or "keratoplasty" is a surgery in which an opaque cornea is replaced by a transparent cornea.
Corneal transplantation is a surgical procedure in which the damaged cornea is removed, replaced by a new, healthy cornea.
Corneal transplantation is done in two common ways:
- Full thickness cornea transplant:
In this case, the whole thickness of the cornea is removed in the affected area and replaced by a healthy cornea.
- Back layer cornea transplant :
Corneal transplantation has been in use since about 40 years ago, in which a damaged or diseased cornea was removed and a healthy cornea was grafted. Gradually, with the development of ophthalmology and the development of new surgical methods, corneal transplantation was transformed, and the surgeons only succeeded in removing the affected part of a damaged cornea and attaching the healthy layer of a donated cornea instead.
Corneal transplantation types
- Automated lamellar therapeutic keratoplasty (ALTK):
Only the affected corneal surface layer is removed and replaced by the same portion of a healthy transplanted cornea.
- Deep Anterior Lamellar Keratoplasty (DALK):
This surgical method is used when the patient has wide disorders in the surface and upper layers of the cornea.
- Descemet Stripping Automated Endothelial Keratoplasty (DSAEK):
This surgical method is used when the patient suffers from corneal endothelium (on the inner surface of the cornea) disorder and the superficial and intermediate parts of the cornea remain healthy. The thickness of this bonding layer is about 90 to 180 microns.
- Descemet Membrane Endothelial Keratoplasty (DMEK):
The latest method is endothelium transplantation, in which a very thin membrane is transplanted in a thickness of 5 to 10 microns. This method, in contrast to other methods, requires a greater degree of surgical expertise and more complexity than other methods.
1. Make better vision in cases where corneal opacity leads to blurred vision.
2. Repairing corneal perforations to protect the internal structure of the eye sphere
3. Treating severe pain which is caused by a disease or corneal edema (swelling of the cornea)
4. Eradicating corneal infection that is not treated by the medications
1. Patients who suffer from corneal edema (swelling of the cornea) that is caused after cataract surgery.
2. Patients with Keratoconus.
3. Patients with corneal opacity that is commonly caused by frequent ocular herpes or microbial infections.
4. patients with chemical burns of the cornea.
5. Patients with genetic diseases that cause corneal edema or opacity.
The transplanted corneas after death are removed from the eyes of people who were willing to help others by cornea donation. Without the charity donation of these people no corneal transplantation surgery is possible.
All corneas donated in Iran are kept at the Eye Bank of the Islamic Republic of Iran. In Eye Bank these corneas are carefully examined to ensure their health. All donated corneas are also controlled for diseases such as AIDS and hepatitis to prevent the transmission the diseases to corneas recipients.
Note: Approved corneas are stored in Iran's Eye Bank for 2 to 8 days and are provided to people in need; a healthy cornea is used at least to treat 3 patients.
For corneal transplantation surgery the patient usually should be admitted to Noor Eye Hospital of Tehran, in Iran before surgery in order to carry out the necessary tests and examinations. Usually, before the patient is hospitalized , the hospital communicates with the Eye Bank for reserving the cornea, but anyway, on the day of surgery, the suitable cornea for the corneal transplantation may not be available in the Eye Bank, and as a result, surgery is postponed to another day.
The surgery is done under general anesthesia. Of course, if there is no possibility of general anesthesia due to other diseases, such as heart or pulmonary diseases, the surgery is done under local anesthesia so that the patient becomes sleepy by medications and the eye becomes insensitive to pain, then the patient does not feel pain.
During the surgery, the surgeon uses a special microscopic instrument to remove a round section of the defective cornea from the patient’s eye and replaces it with a similar round section of the healthy donated cornea. After placing the donated cornea in the patient’s eye, the surgeon stitches it into the place with an ultra-fine thread. It should be noted that surgery takes between one and two hours. Depending on the situations, sometimes, in addition to corneal transplantation, Cataract or Glaucoma is also carried out at the same time. After the end of the surgery, the eye is dressed.
After surgery, your eye is at first very vulnerable to blows on it, you must be careful not to touch or press your eye. Because even a small blow may damage it seriously. Therefore, it is necessary to wear a protective plastic eye shield during the first weeks after the surgery, so that it does not hit the eye. During this time avoid bending down, pushing, lifting heavy objects or bending your head forward. If you have to pick things up from the floor, don't bend your waist, just bend your knees and keep your head up. When you wash your hair, make sure that the water and shampoo do not enter your eyes. Heavy exercises are prohibited. Don't take any more physical exercise than a brisk walk after the surgery. Above all, avoid rubbing and poking your eyes during this period.
Note: lf you do a desk job, you can usually go back to work after about two weeks, but if your job is more strenuous, you will be advised to stay off work for at least six weeks, or in some cases even longer.
Since after corneal transplantation surgery, the healing process of the cornea tissue is too late, and an eye with a corneal graft is never as strong as a normal eye the following should be observed:
1. Always wear sunglasses or large prescription glasses with resistant glass to prevent accidental strokes.
2. Avoid major contact sports such as wrestling, judo, soccer where there is a chance to hit.
3. Avoid activities that are likely to hit, and do not interfere with anyone.
4. When you are swimming or doing physical activities, be sure to wear protective eye wears.
Note: Failure to observe these tips can result in blindness.
In the first days after transplantation, examinations are usually performed on a daily basis. After one to two weeks, the intervals between examinations are usually three to four days, and gradually the intervals of examinations are prolonged, so that the ophthalmic examination is repeated every few weeks after the cornea transplant.
After 6 months, the intervals of examinations are prolonged and they occur every 3 to 6 months. The doctor examines the patient at any time in terms of visual acuity, stitches condition, the possibility of cornea graft rejection, and mediation complications such as Glaucoma and Cataracts.
Note that after cornea transplantation, even many years after the surgery, any abnormal symptoms such as vision loss, tearing, pain, foreign body sensation, photophobia (light sensitivity), or redness of the eye should be reported to your ophthalmologist within 24 hours at most.
Also after the corneal transplantation, it is usually necessary to use antibiotic drops for several weeks and steroid drops that control eye inflammation for several months. Other eye drops such as artificial tears or pressure-lowering topical eye drops may be prescribed by the ophthalmologist. After the surgery, be sure to take the drops carefully according to the ophthalmologist's instructions and avoid the arbitrary discontinuation of the medication. The eye drops abuse leads to the destruction of the grafted cornea and blindness.
The result of the corneal transplantation depends to a large extent on the primary disease, which is due to corneal transplantation.
In patients who have undergone surgery due to noninfectious corneal opacity, keratoconus or mild corneal edema (swelling of the cornea), the success rate is very good and about 90%. In cases where corneal transplantation is due to spots of ocular herpes or severe corneal edema, the success rate is above 80%. In emergency cases where corneal transplantation is performed to control corneal infection or repair the cornea hole, it is less likely that the cornea remains clear, but corneal transplantation is still required to maintain eye structures.
The most common major complication of the corneal transplantation is the development of Astigmatism, which usually is improved by adjusting and removing stitches, and wearing glasses or contact lenses.
Another important complication is cornea graft rejection which, if not treated promptly, causes the grafted cornea become opaque. The transplant rejection occurs when the patient's immune system identifies the transplanted cornea as a stranger's tissue and tries to destroy it. Rejection can start as soon as two weeks after a graft, but is commonest several months afterwards.If the rejection is diagnosed soon, it can be treated with steroid eye drops, and occasionally with steroid tablets or injecting drugs around the eye, but in advanced cases of rejection, the rejection may not be managed by medications and a second corneal transplantation surgery is needed which its success rate is less than the first one. For this reason, it is advisable to contact your ophthalmologist within 24 hours, if you have any of the following symptoms in the eye that has the transplanted cornea:
2. Severe redness of the eyes or around the cornea
3. Light sensitivity
4. Abnormal eye tearing
5. Blurred vision
6. Feeling foreign body in the eye that can be due to loose or torn stitches.
Other major complications of the corneal transplantation are not very common, however, there are likely to be complications such as intraocular bleeding, infection, cataracts, glaucoma, recurrence of the previous disease in the transplanted cornea and retinal tear.
What is the condition of the eye and the patient’s vision after corneal transplantation surgery?
When does the transplanted cornea heal and the stitches can be removed?
What should we do to get better vision during the first few months after the surgery?
What is the main symptom of corneal opacity?
How many percent is it likely that the transplanted cornea is not rejected?
Is absolute rest necessary after corneal transplantation surgery?
What is the effect of organ donation on the corneal transplantation?
- What is the condition of the eye and the patient’s vision after corneal transplantation surgery?
After the surgery when the patient regains consciousness, feeling discomfort and pain is common and normal. The next day, the eye dressing is opened and the eye is examined. On the first day after the surgery, the vision is completely blurry. Blurred vision gradually and slowly improves, so you should not expect good vision in the first few days and weeks after the surgery. The eye pain, sensitivity and tearing usually improve after 34 days. Usually, one day after the surgery, the patient is discharged from the hospital, but for four weeks it is necessary to check the transplanted cornea every couple of days.
- When does the transplanted cornea heal and the stitches can be removed?
After the corneal transplantation, the vision is blurred. It takes about one to two years to have good stable vision, heal the cornea and remove all the microscopic stitches.
- What should we do to get better vision during the first few months after the surgery?
During the first few months after surgery, your vision may fluctuate. For this reason, even the use of prescription glasses may not be helpful. After a few months, however, the use of prescription glasses or contact lens helps to improve vision. Of course, in a small number of patients, it is necessary to perform a repeated surgical procedure on the transplanted cornea to reduce astigmatism and improve vision.
- What is the main symptom of corneal opacity?
The main symptom of corneal opacity is a gradual decrease in vision, which the corneal transplantation can help improve it.
- How many percent is it likely that the transplanted cornea is not rejected?
The success rate of corneal transplantation depends on the primary corneal disease. For example, in patients with keratoconus the success rate is more than 70%, but in cases of corneal infections or burns, the success rate is lower.
- Is absolute rest necessary after corneal transplantation surgery?
Resting is recommended to prevent secondary complications and cornea graft rejection. If you do a desk job, you can usually go back to work after about two weeks, but if your job is more strenuous, you will be advised to stay off work for at least six months.
- What is the effect of organ donation on the corneal transplantation?
Without the selflessness of thousands of donors, corneal tissue donors, and their families, corneal transplants would not be possible.Expanding the culture of donation helps a patient in need of a cornea.