Researchers Restore Vision by ‘Growing’ Eye Cells
July 12, 2000 — This one’s a real eye-opener: scientists in California and Taiwan have been able to use cells grown in the laboratory to restore useful vision to a small number of patients with severe visual loss caused by damage or disease of the cornea, the transparent outer membrane that covers the central portion of the eye.
“I’m about 20/40, whereas before the operation, I was about 20/200, so it’s a tremendous jump in the right direction,” says James Beebe, a 78 year-old retired securities trader from Oregon, in an interview with WebMD. His corrected vision is good enough for driving in most states. Until the surgery, Beebe’s vision was so poor that he had to give up driving, could only read with help of a large magnifying glass, and could only recognize faces when they were just a few inches away. But today, nearly two years after his surgery, he’s back behind the wheel, can read without cumbersome visual aids, and can use the computer.
Beebe, who suffered injuries to his corneas from a rare allergic reaction to drugs he was taking to control glaucoma, was one of 14 patients who underwent surgery at the University of California at Davis to repair their severely damaged corneas using bioengineered corneal grafts.
The patients all suffered from one of several different rare conditions — caused by injury or disease — in which the eye’s usual ability to create a new surface has been destroyed. That’s because the normal population of corneal stem cells is missing or damaged. Corneal stem cells are primitive cells that are primed to turn into corneal cells on demand, such as when the aging cells need to be replaced by fresh new ones, or when reinforcements are called out to repair damage to the cornea.
When the eye loses its population of stem cells — as can happen after burns, trauma, or certain diseases — the ability to self-repair dies with it, and the cornea can become severely scarred or even opaque, like a heavily frosted window. Previous therapies, including conventional transplants of corneas taken from the eyes of people who have died, had all failed in these patients, because the eyes lacked the natural ability to promote healing in the cornea.
To correct the problem, Ivan R. Schwab, MD, and R. Rivkah Isseroff, MD, took corneal stem cells that had been harvested either from the healthy remaining eye of the patient or from a living donor — in Beebe’s case, his sister. The donors volunteered to spare a small portion of cells from the outside edge of the cornea, right where it meets the white of the eye. The procedure requires only a small incision and does not appear to threaten the health of the donor’s eye, researchers say. Schwab is professor of ophthalmology and Isseroff is professor of dermatology at the University of California at Davis.
As the researchers describe in the July issue of the journal Cornea, the cells were then grown in a lab dish. The new cornea is then transplanted onto the damaged cornea of the patient.
Ten of the 14 patients had successful results, defined as complete recovering of the corneal surface, stable or improved vision, and no recurrence of disease. One patient had vision improve from the ability to only count fingers before the transplant to 20/30 after; and a second went from counting fingers to 20/60. Both were considered success stories.
“The real exciting part of this is that … other mucous membranes such as bladder, gut, lung, vagina, or rectum, probably, can be grown in the laboratory to be retransplanted into patients who have either traumatic or [disease] damage,” says Schwab in an interview with WebMD.
In another study published in the July 12 issue of TheNew England Journal of Medicine, Ray Jui-Fang Tsai, MD and colleagues from Taiwan report on the use of a similar technique in six patients with severe corneal disease.
All six damaged eyes had complete recovering of the surface within two to four days, and by one month there was significant improvement of clarity of the cornea, the authors write. The average visual perception in five of the six eyes improved from 20/112 (severely impaired) before surgery to 20/45 (mildly impaired) after transplant. The sixth patient, who had total clouding of the cornea due to a chemical burn, had perception of 20/200 in the treated eye 15 months after the graft.
And now, according to the Associated Press, the number of successful transplants done by the researchers from Taiwan has increased to 60 out of 90 attempts.
“This is building on what a lot of us have been working on, and that’s stem cell transplantation for rehabilitation of severely injured eyes; they’ve just taken it to another level,” Edward J. Holland, MD, who was not involved in the studies, tells WebMD. “Potentially we can minimize risk to the donor, and also potentially bank stem cells that we could use at another time in the case of rejection or inflammation.” Holland is professor of ophthalmology at the University of Cincinnati and director of cornea at the Cincinnati Eye Institute.
“The exciting part is that we know this can be done; the frustrating part is that we don’t have all the answers,” Schwab tells WebMD. He adds more improvements need to be made to the procedure.
Things still aren’t perfect for Beebe either. “I was hoping that the stem cells would help the cornea more, and it would get better, and better, and better,” he tells WebMD. “But it’s been stable, and that’s great, because that was my problem: [before the surgery] it was getting worse and worse and worse.”