Comments /2236 Views / Tuesday, 13 March 2012 01:07
Corneal transplants can restore vision to eyes damaged by corneal diseases or injuries. The cornea is the clear front layer of the eye that allows light to pass through the pupil and lens to focus onto the retina, enabling you to see well.
When the cornea is damaged through injuries or diseases, it may become scarred or swollen. This causes distortion and scattering of light, resulting in glare or blurry vision.
“The only way to regain vision for an eye with a clouded cornea is through a corneal transplant, if the rest of the eye including the optic nerve and the retina are in good condition,” says Dr. Lee Hung Ming, Ophthalmologist and Medical Director from Parkway Eye Centre, Gleneagles Hospital.
Dr. Lee explains that it is recommended when the patient’s vision from a damaged cornea cannot be corrected with glasses or contact lenses, or when medications are unable to relieve the painful corneal swelling.
Addressing the media at a gathering organised by ParkwayHealth in Singapore in February, he said that cataract is the most common reason for cornea transplants, while asserting that of all transplants, cornea transplants carry the highest success rate.
In fact Sri Lanka is among the world’s largest cornea providers, donating about 3,000 corneas a year.
A state-of-the-art Government eye bank was opened last year in February by President Mahinda Rajapaksa, funded by Singapore donors, at the National Eye Hospital premises. The Lee Foundation of Singapore, National Eye Centre and the National Eye Bank of Singapore provided financial and technical assistance for this project.
In collaboration with the Singapore Eye Bank, Sri Lanka provides corneas to Singapore as well. Citing Sri Lanka as one of top donors, Dr. Lee revealed that corneas are also harvested from local donors as well as from internationally accredited eye banks from the United States and Philippines.
“We prefer Sri Lanka or the Philippines cornea donors since the corneas are fresher. With the availability from Sri Lanka and the Philippines, cornea supply waiting time is one to two weeks,” noted Dr. Lee.
Reasons for corneal transplant
Dr. Lee says: “Corneal transplants are highly successful, with over 90 per cent of the operations achieving restoration of sight. However, as with any surgery, there are always some risks involved. Complications that can occur include infection, cataract formation, glaucoma and graft rejection.”
According to Dr. Lee, corneal graft rejection arises from the reaction of a patient’s immune system to the donor tissue. However, unlike other types of organ transplant, the rate of rejection is lower with the cornea because it normally does not contain any blood vessels.
Dr. Lee says that rejection reactions may occur within weeks after the surgery, or it may happen 20 years later. If a full rejection does occur, the patient may need to undergo another corneal transplant.
Corneal transplant surgery is usually done as a day surgery although some may require a short hospitalisation. It is carried out under regional or general anaesthesia. The surgery takes about an hour.
Availability of donor cornea
Once a patient, Singaporean or non-Singaporean, is deemed by his doctor to be a candidate for transplantation, he will be put on a waiting list with the Singapore Eye Bank for a suitable cornea. The waiting time can be as soon as within a week or up to a few months.
Corneas are harvested from local donors as well as from internationally accredited eye banks from the United States, Philippines and Sri Lanka.
For overseas patients
Once the eye bank informs the doctor of the availability of a donor cornea, the patient will be contacted immediately. The date and time for surgery will be made and the patient will then make the necessary arrangements to travel to Singapore for the transplant surgery within the next one or two days.
Usually the patient can be discharged and travel home after five days. Arrangements will then be made to return to Singapore for review by his doctor to make sure that all is well.
Methods of corneal transplant
There are a few types of corneal transplant surgery, the most common of which is the Penetrating Keratoplasfy. With this method, a full-thickness damaged cornea is replaced by a full-thickness graft from the donor tissue. This new cornea is sutured into place with fine stitches.
In Femtolaser-assisted Blade-free Corneal Transplant, a highly sophisticated laser is used to cut the cornea of the recipient and the donor without the need for a blade. In corneal injury involving only the superficial layers of the cornea, a Lamellar Keratoplasty or a Deep Anterior Lamellar Keratoplasty may be performed.
This procedure enables preservation of the healthy inner layer of the cornea while replacing the scarred outer layers. The likelihood of a graft rejection is extremely low with this method as the inner layer, known as the endothelium, is left untouched.
In cases of hereditary corneal diseases where the endothelium becomes damaged, it can be treated with a Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK).
In this highly refined technique, the surgeon removes only the diseased endothelium and replaces it with healthy endothelium from a donor tissue. No sutures are needed and the visual recovery is faster as compared to the conventional technique.
A leading provider of private healthcare services in Asia, ParkwayHealth’s reputation is the result of quality clinical outcomes and comprehensive care, made achievable with an extensive network of hospitals, integrated healthcare facilities and over 40 years of experience in hospital development.
ParkwayHealth operates three hospitals – Gleneagles Hospital, Mount Elizabeth Hospital and Parkway East Hospital – and several medical centres in Singapore, where specialist care is administered in one place.
ParkwayHealth operates medical services and facilities house over 3,400 beds and 1,200 accredited specialists. Over the years, it has achieved numerous firsts and recorded many milestones, which is a testament to its efforts in healthcare.
ParkwayHealth has several hospitals and medical offices across the globe and also operates a ParkwayHealth Patient Assistance Centre in Sri Lanka.
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