Treatments that are effective in 90 percent of patients are greeted with great acclaim, as they should be. But what happens when you’re in the remaining 10 percent who can’t be helped?
Welcome to Linda Block’s world. Block has keratoconus, a degenerative disease of the cornea that can cause blurring, distorted vision, and sensitivity to light. In its early stages, the condition can be treated with glasses or special contact lenses. But in more severe cases, like Block’s, a corneal transplant may be needed to fix the problem.
Block has had five corneal transplant surgeries to replace the damaged tissue in her left eye with corneas from donors’ eyes. (Block’s right eye is too damaged to repair.) Each time, her body rejected the transplanted corneal tissue, causing visual cloudiness and deterioration.
Block’s vision became progressively worse with each surgery. At 61 years old, she was legally blind, and her options were limited.
But she was an ideal candidate for a new type of prosthetic (or artificial) cornea, according to her ophthalmologist, Stephen C. Kaufman, M.D., Ph.D., a renowned leader in corneal transplantation research.
“Corneal transplants using donated corneas are successful in 90 percent of patients,” explains Kaufman, director of cornea and refractive surgery in the University of Minnesota Medical School’s Department of Ophthalmology. “But patients like Linda, whose bodies reject a corneal transplant, are increasingly likely to reject subsequent transplants. This puts them in a high-risk group.”
An artificial solution
Kaufman, who holds the Elias Potter Lyon Research Chair in Ophthalmology, is one of only a few surgeons in the country to use the Boston Keratoprosthesis, or KPro, prosthetic cornea and is the only Minnesotan ophthalmologist to do so.
Corneal prostheses are generally implanted without the use of donor tissue. However, the Boston KPro prosthesis is attached to tissue from a donor cornea before it is implanted in the eye. The donor tissue serves as a “scaffolding” or bridge between the patient’s eye and the device.
And although some donor tissue is used with the Boston KPro, rejection is not an issue, Kaufman says. Because the prosthesis is made with a special kind of plastic, it provides an exceptionally clear central lens for patients to see through, he says, and the scarring and cloudiness typical of rejection are irrelevant because the Boston KPro cornea always remains clear.
“Tissue takes a long time to heal and can get cloudy if it is rejected by the body,” Kaufman says. “A plastic cornea is more like having a camera lens right in the center of the cornea.”
Most suitable for patients with severely damaged corneas, artificial cornea transplant surgery takes about the same amount of time as conventional surgery using only a donor cornea.
Block received a Boston KPro prosthetic cornea in January. The recovery and restoration of vision after a corneal transplant can take up to a year, but just days after her artificial cornea was implanted, Block says she could see better than she had in years.
“My vision got clearer and clearer every day, but I could tell a big difference already by day four,” says Block, who now must use daily eye drops and go in for follow-up appointments with Kaufman every three to six months for the rest of her life.
But these minor inconveniences are a small price to pay for the independence Block now savors after so many years of relying on others, she says.
“It’s just being able to do everyday things, like go to the grocery store by myself,” Block says. “I used to have to ask for help with reading the prices or finding my way down the right aisle.
“Now I can see to clean my house right again. I used to think it was clean and then my husband, James, would come along behind me, cleaning everything I had missed. I didn’t even realize that the kitchen and bathroom tile had a pattern in it until after I had this surgery.”
Artificial cornea transplantation is not used as a primary surgery today; currently it’s used only after multiple transplants with donated corneal tissue have failed. And while central vision improves with an artificial cornea, peripheral vision cannot be corrected.
So while it isn’t the perfect treatment, “for patients like Linda who really have no other options, an artificial cornea is almost a miracle,” Kaufman says.