The procedure offers patients the chance of perfect eyesight with a rejection rate of one per cent or less
Having already undergone two corneal transplant operations in his left eye over the last 10 years, Mr Chok Teck Chow was more than a little apprehensive about going through another one in his right eye.
“Previously, I needed 20 stitches and took six months to recover,” said the 59- year-old who is semi-retired.
But he needn’t have worried. With an improved corneal transplant procedure offered at the Singapore National Eye Centre (SNEC), he suffered only a few days of blurry vision. “By the fourth day, I could see well enough to go out by myself,” he said.
The new procedure, which is known as Descemets Membrane Endothelial Keratoplasty (DMEK), is the latest innovation in minimally invasive corneal transplantation. It involves transplanting a delicate sheet of corneal cells 1/100 mm thick, which is 10 times thinner than what was required in a previous commonly used procedure at SNEC.
The cornea is the transparent, protective outer layer of the eye, and a transplant is the standard means of treatment in patients whose corneas are cloudy from ageing or disease.
Patient's original cornea is left mostly intact
With DMEK, the patient’s original cornea is left mostly intact, so it’s not immediately apparent that he’s had a transplant. It may also be possible for the patient to attain 100 per cent vision within a few weeks of surgery.
Professor Donald Tan, Medical Director, SNEC, said: “The future will be DMEK. We have a chance for a transplant that provides for 20/20 vision and a rejection risk that is one per cent or less.”
This new, sutureless technique was invented in Europe and first performed in Asia by Prof Tan in September 2010. Since then, he has performed three such corneal transplant procedures which cost between $1,500 and $1,700 each, after subsidies at SNEC. Private patients pay up to $5,900.
The current downside of the new procedure is that it is an extremely difficult form of surgery. As the membrane transplanted is ultra thin and delicate, it tends to wrinkle into a tight roll when touched, potentially damaging the corneal cells when surgeons try to uncoil it.
To get around the problem, Prof Tan and his team at the Singapore Eye Research Institute have developed a method that is safer and easier to perform, using a new DMEK surgical insertion device currently awaiting a patent.
Each year, about 350 corneal transplants are performed locally, of which about four in 10 involve patients with ageing corneas. With the ageing population, this number is expected to grow.