New cures for blindness

Source: Best Health Magazine, September 2011

For practically every condition that affects eyesight, clusters of scientists are working on exciting new treatments. Best Health researched advancements being made around the world, and found one of those breakthroughs is restoring vision for people who suffer from a genetic condition.

When the patch was lifted from Dale Turner’s right eye two days after experimental surgery in 2008, the 24-year-old literally couldn’t believe his eyes. ‘It was amazing when I walked outside,’ recalls Turner, who lives in Richmond Hill, Ont. ”I was able to see extremely bright colours in a way I never had before.’

Turner has been legally blind (a term used to describe people who can’t see better than 20/200) since birth due to a genetic eye disease called Leber congenital amaurosis (LCA). One in 80,000 people has the condition, which affects the way a retina senses light. ‘But Turner has been enjoying dramatically improved vision in the one eye he had treated as part of a clinical trial at the University of Pennsylvania three years ago. A team of three ophthalmologists and a molecular geneticist injected a virus carrying copies of the healthy gene into a small area of Turner’s right retina.

Since the procedure, he has found it much easier to distinguish colours and see in dim light, both things he had difficulty with before. ‘It’s been an extremely positive experience,’ says Turner, who knows that his participation in the study has helped pave the way for other people with his condition to be treated. (He’d love to have the procedure again on his other eye, but has to wait until it is widely available.)

Artur Cideciyan, a research professor of ophthalmology at the University of Pennsylvania’s Scheie Eye Institute and co-investigator on the trial, says he has seen equally impressive results with some other human subjects: After the surgery, day vision was up to 50 times better in people with LCA, and night vision up to 63 thousand times better. ‘The effects of the treatment have been proven to last unabated for at least one year,’ Cideciyan says. (Since no human gene therapy has yet been approved by the U.S. Food and Drug Administration, it may be years before this becomes used as a standard treatment.)

Corneas made in the lab

Genetic diseases aren’t the only cause of blindness. Many types of vision loss stem from damage to the cornea’the transparent, dome-shaped ‘window’ at the very front of the eye’resulting from injury or disease. And although a corneal transplant can sometimes be a cure, ‘there’s a worldwide shortage of corneas, which is expected to grow as the population ages,’ says May Griffith, a tissue engineer affiliated with the University of Ottawa Eye Institute.
Currently working at Linköping University in Sweden, Griffith has performed groundbreaking work with biosynthetic corneas that were developed in Canada. The corneas are made from recombinantly produced human collagen that is chemically treated and moulded into the shape of a normal cornea. Once the patient’s damaged tissue is removed and the biosynthetic corneas are placed, the patient’s own nerves and cells grow into the implant and begin to work properly.

Griffith and her colleagues recently tested the safety of the biosynthetic corneas on 10 subjects, six of whom saw their vision improve from an average of 20/400 to 20/100. Compared to patients who receive donor corneas, Griffith says, ‘we found that our patients could have their sutures removed sooner, and they could also get off anti-rejection steroids a lot sooner.’ All 10 subjects can now wear contact lenses comfortably, something that hadn’t previously been possible with their damaged corneas. Griffith plans to refine the technique in future trials to help a wider range of people. It will be at least five years before the treatment becomes available for more widespread use in clinical trials, which she hopes will include centres in Canada.

In another study, published last year in The New England Journal of Medicine, a research team in Italy has been able to use patients’ own stem cells to restore their sight after their corneas were burned in accidents. The stem cells were cultured in the lab and then grafted onto the damaged eyes. Astoundingly, three quarters of subjects were able to see again with 20/20 vision within a year, and results were stable for up to 10 years.

A tooth for an eye?

A new procedure known as MOOKP, or modified osteo-odonto-keratoprosthesis, can give sight to people blinded by severe corneal damage’by inserting one of their own teeth into their eye. Sound strange? The extracted tooth and surrounding bone, which is sculpted into a flat base, actually holds a prosthetic lens that allows the person to see. Since the base is made from the person’s own tissues, there’s little risk of rejection. A version of the procedure was pioneered in the 1960s, but more recent development by an Italian ophthalmologist has led to restored vision in people who aren’t candidates for a corneal transplant. In 2009, a 60-year-old woman from Mississippi whose corneas were badly scarred by Stevens-Johnson syndrome (a skin disorder that causes damage to skin and tissues) became the first person in the U.S. to undergo MOOKP. After the procedure, she saw her youngest grandkids’ faces for the first time. MOOKP is not yet performed in Canada.

Microchip implants

Researchers at the Massachusetts Institute of Technology have been working on a microchip implant for the eye. The implant receives images from a camera mounted on a pair of glasses the person wears, then sends information directly to the brain through the optic nerves. It may not produce ‘normal’ vision, just as a cochlear implant doesn’t restore regular hearing. But the team is hoping the visual information provided by the implant will offer more independence to people with common forms of blindness such as retinitis pigmentosa and age-related macular degeneration. Researchers expect to try their implant on blind subjects within the next two years.

This article was originally titled "Breakthrough treatments for blindness" in the September 2011 issue of Best Health. Subscribe today to get the full Best Health experience’and never miss an issue!