Babies born with cataract may soon benefit from a new surgery that permits stem cells to regenerate eye lens and make it functional.
After testing the treatment to animals and a small group of human subjects, researchers from the University of California San Diego (UCSD) found that the procedure entails fewer complications than the current method. The surgery also resulted in excellent visual function in all of the 12 children who received the treatment.
"The potential of this technique is mind-boggling," says Mark Daniell, corneal research head from the Centre for Eye Research Australia in Melbourne, who was not involved in the research.
Congenital cataract, which is characterized by the clouding of the lens at the time of birth, is a major cause of blindness in children.
Because the lenses are clouded, light cannot pass through the retina and the patients are left without no visual information in the brain.
Conventional Cataract Surgery
The conventional surgical procedure for cataract in children is to cut a slit measuring about 6 millimeters at the middle of the lens capsule. Eye surgeons will then remove the impaired lens and replace it with an artificial one.
Massive amounts of lens epithelial stem cells (LECs) get lost in the process. LECs are natural stem cells that can produce replacement lens cells in the entire span of a person's life. Production of such cells only reduces as age advances.
The complication rate of conventional cataract surgery is estimated at 92 percent, with the risk of artificial lenses growing opaque through time.
The New Cataract Surgery
The new surgical method relies heavily on LECs. In the study, the UCSD team was able to verify that LECs have regenerative potential in animal models. With this, they devised a surgical technique that preserves the health of the lens capsule and stimulates LECs to develop new lens with vision.
The authors then tested this new method in animals and humans. They tested 12 infants for the new surgery and 25 infants for the standard surgery.
The subjects who underwent the new method had fewer complications and more swift healing. Three months into the procedure, the babies were able to have clear and regenerated biconvex lens.
The group that received conventional treatment had greater reports of inflammation after surgery. They also developed early-onset hypertension in the eye system and more clouding of the lens.
Study lead author Kang Zhang says the success of their study signifies a new approach in the regeneration of new human tissue and the treatment of human disease.
Their study may also pave the way for other regenerative therapies by boosting the human body's ability to regrow.
In the future, Zhang and colleagues plan to further their work by addressing age-related cataracts. Over 20 million people in the U.S. suffer from cataracts. More than 4 million surgeries to remove diseased lens and replace with artificial ones have to be performed every year.
Still, a large population of patients who have undergone surgical treatment continue to suffer from poor vision and rely on corrective eyewear when doing eye-containing activities such as reading and driving.
The authors believe their work can spark up a shift in the conventional cataract surgery and offer patients a safer and more effective option in the future.
The study was published in the journal Nature on Wednesday, March 9.