For the first time, experts who performed cataract surgery on infants took a novel, "regenerative medicine" approach. Eye surgeons removed congenital cataracts in infants and stimulated the remaining stem cells to regrow functional lenses. This brought back vision to infants. With more research, the technique is hoped to help millions of adults too.
Experts who developed the technique in the University of California, San Diego School of Medicine and Shiley Eye Institute, with colleagues in China, explain that it is "less invasive than traditional cataract treatment."
Currently, cataract surgery involves an incision just in front of the eye, removal of the lens from the supporting capsule and replacement with an artificial lens.
In the first-of-its-kind stem cell technique, a slim incision is made at the side of the lens capsule, after which the complete lens is removed. But the empty capsule bag or "scaffold" is left behind. One type of stem cell, called an endogenous stem/progenitor cell also remains in the eye. It multiplies and grows into a new, healthy lens.
Study author Dr. Kang Zhang, the chief of ophthalmic genetics at UC San Diego's Shiley Eye Institute, explained that the traditional technique of cataract surgery destroys more than half of the lens stem cells and needs implantation of a plastic intranet ocular lens.
His team left the lens epithelial stem cells, or LECs, intact. The experts repaired the lens, without requiring implants. The technique was repeated in animals.
"We devised a new surgery to make a very small opening at the side of a cataractous lens bag, remove [the] cataract inside, allow the opening to heal, and promote dormant lens stem cells to regrow an entirely new lens with vision," Zhang said.
Doctors performed the experimental procedure on 12 infants, who had the congenital cataract condition when they were born.
Babies with congenital cataracts need early intervention in order to permit light to get into the brain, allowing for "normal, healthy growth," said Suraj Bhat, associate professor of ophthalmology and director of the Vision Molecular Biology Laboratory at the UCLA Stein Eye Institute. He was not part of the new research, but called it an "extremely exciting" surgery, as an alternative to "an extraordinarily invasive" procedure.
"In early childhood cataracts are very bad. We need light to enter into the eyes at a young age to get proper brain function, otherwise, information does not get transferred to the developing brain," Bhat said.
In order to refract light onto the retina at the back of the eye, the cornea and lens are required to remain transparent as long as the person lives. At present, the cornea and lens involve donor transplants or artificial implants, but the procedure is fraught with risk. The novel technique that uses stem cells to regenerate normal tissue is more promising.
The surgery offers a lot of help to the adult population, who are majorly affected by cataracts.
"We are now planning a study to test this approach in this old patient population. In addition, we are testing if this approach can be used in treating other leading causes of blindness, such as macular degeneration and glaucoma," Zhang said.
The study was published in the March 9 online edition of Nature.
"The study's stem cell engineering has led to the regeneration of transparent lens tissue in children, showing that the concept offers a potential therapeutic approach," wrote Julie T. Daniels, from University College London Institute of Ophthalmology, in an accompanying commentary in Nature.
