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.