These layers work together to protect the eye and provide clear vision. For good vision, the cornea must remain clear, smooth, and healthy. If it is scarred, swollen, or damaged, light will not be focused properly in the eye. As a result, vision is blurry or a person sees a glow.
If the cornea is injured and cannot heal or repair, the ophthalmologist may recommend a corneal transplant, which means replacing the diseased cornea with a clear, healthy cornea from a human donor, according to the American Academy of Ophthalmology (AAO). A human donor is a person who recommends donating (giving) his cornea after his death to people who need it. All donated corneas are carefully tested to ensure they are healthy and safe for use.
Around 185,000 corneal transplants are performed each year worldwide. In the United States, ophthalmologists perform more than 47,000 corneal transplants annually. The top three countries for this process are: the United States, Lebanon and Canada. People, who live in more than half of the countries in the world, are not able to get this surgery, and one of the reasons for this is the lack of donated corneas; Only one cornea is available for every 70 needy individuals, according to the American "Cleveland Foundation".
The success rates at 1, 2 and 5 years for all first-time corneal transplants for 1389 cases were: 79.6%, 68.7% and 46.5%. The success rate, after 5 years, was highest if a corneal transplant for keratoconus was performed at 95.1 per cent, and the lowest if it was performed for previous transplant failure at 21.2 per cent, according to the British Journal of Ophthalmology Br J Ophthalmol.
> How does corneal transplantation take place? And when is it recommended? And what are its complications?
Your Health met with Dr. Hernán Alfonso Martínez Osorio, a consultant ophthalmologist at Barraquer Eye Hospital in Dubai, United Arab Emirates, and coordinator of the first clinic in the Middle East for corneal transplantation at King Khalid Eye Specialist Hospital in the Kingdom of Saudi Arabia. in 2015 through 2021; To answer these and other questions, who stated that when the cornea becomes opaque, cloudy, or distorted due to injury, disease, or genetic conditions, vision can become blurry, or even completely lost, and then a corneal transplant may be necessary, and corneal transplantation can be performed to improve vision. Relieve pain and treat infection or severe damage.
Regarding the corneal transplant, he explained that it is also known as keratoplasty or corneal graft, and it is a surgical procedure to replace healthy corneal tissue from a donor with damaged, opaque or diseased corneal tissue. In general, healthy corneal tissue to be transplanted is usually obtained from corneal banks around the world. This procedure, which involves replacing a healthy cornea from a donor with an opaque or diseased cornea, can restore vision, relieve pain, and significantly improve a patient's quality of life. Corneal transplantation is one of the complex operations that most of them require a highly specialized medical team, including pediatric ophthalmologists, pediatric anesthesiologists, and corneal transplant specialists.
In cases of corneal transplantation for children's eyes, pre- and post-operative care differs from that of adults, so the medical team usually takes extra care and precautions. The transplanted cornea is followed up through a number of visits in the outpatient clinic for corneal transplantation. To check on the status of the cornea and improve vision.
Corneal problems. Eye diseases and injuries can damage the cornea. Here are some common eye problems that can lead to corneal damage:
- Keratoconus, where the cornea is cone-shaped, not dome-shaped.
Fuchs' dystrophy, in which the cells in the inner layer of the cornea do not function effectively.
Eye infections or injuries that scar the cornea.
Previous corneal surgery or other eye surgery that damages the cornea.
> Candidate specifications for cultivation. Dr. Hernan Osorio says it's important to note that not everyone is a good candidate for a cornea transplant, as some underlying eye conditions may need to be treated before a transplant. In these cases, a comprehensive eye examination and evaluation by a corneal specialist is necessary. To determine if a corneal transplant is appropriate.
Another important consideration is the availability of donated corneas. Although the demand for corneal transplants continues to grow, the supply of donated corneas is limited. However, thanks to the tireless work of eye banks and tissue purchasing organizations, the availability of corneas has increased in recent years.
Corneal surgery developments
. Modern surgery. Dr. Hernan Osorio reports that the corneal transplant is much better than it was before and is being performed by a trained and certified consultant, specifically in corneal surgery. There are different types of corneal transplants. In some cases only the front and middle layers of the cornea are replaced, in other cases only the inner layer is removed, and sometimes the entire cornea needs to be replaced.
In modern keratoplasty, the corneal surgeon replaces the diseased layer, and most of the time it is not necessary to replace the entire cornea. First, the damaged layers or cornea are carefully removed, and the new cornea is sewn, or taped, in place. The procedure usually takes one to two hours, and it can be performed under local anesthesia, or general anesthesia, depending on the patient's needs and preferences.
In the days following the transplant, the patient will need to rest and limit physical activity until the eye heals. Antibiotics, lubricants, and anti-inflammatory eye drops are prescribed to help prevent infection and reduce swelling. Most people feel some discomfort, but this can usually be controlled with pain relievers.
After the initial recovery period, most people experience an improvement in their vision. However, it may take several months, or even a year, for the new cornea to fully stabilize and vision to stabilize after the stitches are removed. Regular follow-up appointments with the corneal transplant surgeon will be necessary. To monitor progress and ensure the best possible outcome.
Corneal transplant surgery options. According to the "American Academy of Eye (AAO)", there are 3 options for corneal transplantation, namely:
1. Full thickness corneal transplantation. Complete corneal replacement, when the anterior and inner layers of the cornea are damaged. This is called penetrating keratoplasty (PK), or full-thickness corneal transplant, in which the diseased or damaged cornea is removed and the donated cornea is sewn in place.
In this “PK” option, the recovery period is longer than other types of corneal transplants. Full vision recovery may take up to 1 year or longer. There is a slightly higher risk of corneal rejection than other types of transplants, and it occurs when the body's immune system attacks the new corneal tissue.
2. Partial thickness corneal transplantation. Sometimes the anterior and middle layers of the cornea are damaged. In this case only those layers are removed. The endothelial layer, or thin back layer, is held in place. This transplant is called deep anterior lamellar keratoplasty (DALK) or partial thickness keratoplasty. DALK is most commonly used to treat keratoconus, or corneal bulge.
In this option, the recovery time is shorter than the recovery time after a full corneal transplant. There is also a lower risk of rejection of the new cornea.
3. Endothelial keratoplasty. In some eye conditions, only the innermost layer of the cornea, called the 'endothelium', is damaged. This causes the cornea to swell, affecting vision. Endothelial keratoplasty is a surgical procedure to replace healthy donor tissue with this layer of the cornea. Known as a partial transplant, only this inner layer of tissue is replaced. Here, damaged cells are removed from the inner layer of the cornea called Descemet's membrane. The damaged corneal layer is removed through a small incision, and new tissue is placed in its place. Only a few stitches, if any, are required to close the incision. Much of the cornea is left untouched. This reduces the risk of rejection of new corneal cells after surgery.
Rejection of the new cornea. Rejection of a transplanted cornea may occur when the body's immune system sees the transplanted tissue as something that should not be there and tries to get rid of it. Rejection is a problem for up to 3 out of 10 people who have a full thickness (PK) transplant. The risk is lower with partial thickness surgeries.
Among the warning signs of the body's attempt to reject the transplanted cornea, according to the "American Academy of Eyes (AAO)", are the following: eye pain - eye redness - increased sensitivity to light - cloudy or blurry vision. And when there is one of these signs, you should consult a doctor immediately. To work to stop rejection with medication.
Corneal transplantation can sometimes cause other eye problems, such as:
infection - bleeding - retinal detachment (where the tissue lining the back of the eye pulls away from the eye) - glaucoma (through increased pressure inside the eye)
Even when corneal transplants work as they should, other eye problems may limit the quality of vision, such as: - the
new cornea may not curve uniformly (called astigmatism), or there could be an eye disease, such as macular degeneration or glaucoma, or diabetic retinopathy.
Some people may need more than one corneal transplant. The first transplant may be rejected, or other problems may occur. However, repeat transplants have a higher rejection rate than the first.
Corneal protection. The key to avoiding a corneal transplant is to prevent corneal damage or injury, and this happens as follows:
- Wearing eye protection when working in hazardous environments or during sports.
- Avoid infection by washing hands before touching the eyes, and following medical instructions when wearing contact lenses.
Follow general health guidelines, such as eating healthy foods and maintaining a healthy weight.
Have regular eye exams.
- Not smoking, and quitting it for those who used to smoke.
Finally, Dr. Hernan Osorio confirms that corneal transplantation is a safe and effective procedure that changes the lives of many people, and enables restoration of vision and pain relief for people with a damaged or diseased cornea, and that performing this operation with modern technologies can have a profound impact on a person’s quality of life. With proper care and follow-up, as patients can enjoy better vision, a corneal transplant can be a real gift to eyesight.