Cornea Disease and Cornea Transplantation
The cornea is the central clear transparent part of the eye. The cornea may be become diseased or hazy from various diseases resulting in loss of vision.
Various diseases can damage the cornea. This includes infections and injuries which result in corneal scarring, or swelling and cloudiness of the cornea due to damage or ageing of the innermost layer of cells of the cornea (known as the corneal endothelial layer).
A corneal transplant involves replacing the diseased cornea with a healthy donor cornea. Sometimes, corneal transplants may need to be performed as an emergency to treat severe infections of the eye or to repair areas that are very thin or melted.
Corneal transplant surgery
Corneal transplantation is a surgical operation in which donated healthy corneal tissue is used to replace a diseased cornea to restore vision. The cloudy cornea is first removed and a clear and healthy donor cornea is placed and stitched in place.
When all the layers of the cornea are involved, a full thickness corneal transplant is required (Penetrating Keratoplasty). When only a portion of the cornea is affected and the disease has not extended to the all the layers of the cornea then only the diseased portion (either the front portion or the back portion) may be partially removed, and a partial thickness donor cornea is placed. This is known as a Lamellar Keratoplasty.
If a significant cataract (cloudy lens) is present, the cataract may be removed at the time of the corneal transplant operation and an intraocular lens is implanted.
In most instances, first-time corneal transplants may be performed without the need for oral immunosuppression, and only eye drop medication is required. Unlike other forms of organ transplantation, corneal transplantation may be repeated several times if previous transplants have failed. However, the success rate of repeat transplants becomes lower with each transplant and anti-rejection tablets may be required to prevent graft rejection in the subsequent transplants.
Artificial Cornea Transplant
In eyes which have had repeated corneal transplants that have failed or in eyes with complex cornea and ocular surface disorders, an alternative treatment is an artificial corneal transplant. The most established artificial corneal transplant in the world today is the Boston Keratoprosthesis.
Dr Ang is one of the few Asian Ophthalmologists to have undergone specialized training for this procedure at Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, USA. He was the first in Singapore and South East Asia to perform the Boston Keratoprosthesis (artificial cornea) transplant surgery.
Corneal transplants are best performed by surgeons who have undergone specialised training in cornea surgery. Dr Leonard Ang completed his cornea specialist training in Singapore and went for further advanced training in some of the top centres in the world, including Kyoto Prefectural University of Medicine in Japan and Harvard Medical School, Massachusetts Eye and Ear Infirmary in Boston, USA.