A corneal transplant is an effective means of restoring vision for patients suffering poor eyesight as a result of a diseased or cloudy cornea.
If the cornea is clouded, light is unable to pass through to the retina, causing decreased vision or blindness.
Scarring from either injury or infection can cause cloudiness or opaqueness in the cornea. In the case of a cloudy swelling of the cornea, it may be part and parcel of the aging process. This layer unable to "grow back" or regenerate, can only be replaced via this transplant technique.
Many patients undergoing the surgery may recover sight from the transplant if the nerve and retina at the back of the eye are still healthy.
Unlike other forms of organ transplantation, cornea transplants can be repeated several times if previous transplants have failed. However, the success rate for repeat transplants may decrease over time.
In a conventional cornea transplant, the surgeon replaces the entire cornea with a donated cornea from a deceased patient. Now, with new cornea transplant methods, only the damaged layer of the cornea is replaced. These have proven to be safer and allow faster recovery time for patients.
Several hundred patients have now benefited from two new cornea transplant techniques: the Deep Anterior Lamellar Keratoplasty (DALK) technique for the front layers of the cornea, and the Descement's Stripping Automated Endothelial Keratoplasty (DSAEK) for the inner layers of the cornea.
These techniques are now available at the Singapore National Eye Center (SNEC), an institution of the SingHealth group.
Unlike the conventional form of transplantation (known as the Penetrating Keratoplasty), the new transplant techniques employ microsurgical dissection, automated microkeratomes and new emerging femtosecond surgical lasers to finely separate the different layers of the 0.5 mm thick cornea. Through these methods, only the damaged layers of the patient's cornea are replaced while healthy layers are retained.
"The new methods significantly lower the risk of rejection, provide better and faster visual recovery, require no stitches, and have fewer complications. This means shorter recovery time and therefore lower costs to the patient," said Prof. Donald Tan, Medical Director at SNEC.
For example, it has been shown that patients who underwent the DSAEK procedure regained their vision in one month instead of the usual six months required for conventional full-thickness transplants.
"Lamellar transplants are more challenging and take twice as long to do. But the results are worth the extra work," added Tan. Today, around 60 percent of cornea transplants at the SNEC are performed using these new techniques.
One major advantage of these cornea transplant techniques is that each donated cornea can be used on more than one patient.
Improvements in technology and surgical instrumentation have allowed for the development of newer techniques.
For example, in DSAEK, the inner diseased part or endothelium of the cornea is replaced by the equivalent healthy tissue from donor corneal tissue. It has been considered the greatest advancement in cornea surgery in 100 years.
To date, the SNEC has performed about 100 DSAEK procedures with excellent results. The results of the patient's visual outcomes are now equivalent or even exceed those reported by leading centers in the USA and Europe for Caucasian eyes.
The patient's visual rehabilitation is also faster with the new procedure compared to conventional cornea transplantation.
"We have been doing further research in improving this surgery with novel insertion devices and the use of femtosecond laser technology. What DSAEK offers is state-of-the-art cornea surgery and at SNEC, we have led the field in customizing the surgery so it can be used on Caucasian as well as Asian eyes," said Tan.
Recently, a Canadian boy who lost one eye to a rare disorder of the body's mucous membranes -- called Stevens-Johnson syndrome -- and was close to losing the sight in the other eye, underwent a successful cornea transplant in the SNEC.
A man from Thailand, who was unable to get rid of an eye infection that had baffled doctors there and in the U.S., was also eventually treated successfully at the SNEC.
Many patients, both local and internationally, have also benefited from the new modified DSAEK procedure for Asian eyes, developed at the SNEC. It has allowed the possibility of restoring sight in patients who may have been initially turned away from other centers for repeat full-thickness cornea transplantation.
Each year, the SNEC carries out about 250 cornea transplants, of which one-third are on foreign patients. The success rate is more than 90 percent.
The SNEC Corneal Transplantation Programme works closely with the Singapore Eye Bank, which provides a large number of high quality donor corneas for transplants.
The SNEC is one of the few centers in the world to offer these evolutionary methods of cornea transplant and has become a teaching center to eye surgeons from other countries for these surgical techniques. It is also fast becoming an international referral center for cornea transplants, especially complicated procedures, worldwide.
c2008 FlyFreeForHealth
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