Health  

Scientists advance cure for blindness

Blindness.<br />Photo credit: Lifehack

Surgeons have attempted for the first time to halt a common form of blindness with a single injection of gene therapy.

A team from Oxford University has for the last 12 years been experimenting with gene therapies to slow or halt the progress of different eye conditions.

But until now most of the treatments they have carried out have been for relatively rare problems, such as choroideremia, which affects 1,200 people in Britain, and retinitis pigmentosa, which affects 16,000.

Now the surgeons have launched their first attempt at halting age-related macular degeneration – known as AMD – which is the most common cause of blindness and affects 600,000 people in the United Kingdom (UK).

The team is carrying out a trial of ten patients at Oxford Eye Hospital.

The small trial is mainly designed to test its safety – but in time it should give an indication of whether the treatment will work, in which case a much larger trial will be launched.

The first patient, Janet Osborne, 80, who underwent the treatment under local anaesthetic last month, said the central vision in her left eye has deteriorated and is very hazy, making household tasks very difficult.

“I still enjoy gardening with my husband, Nick, who grows a lot of vegetables,” she told BBC News.

“If I can keep peeling and cutting the veg, and retain my current level of independence, it would be absolutely wonderful. I wasn’t thinking of me.

“I was thinking of other people. For me, I hope my sight doesn’t get any worse. That would be fantastic. It means I wouldn’t be such a nuisance to my family.”

Project leader Professor Robert MacLaren, whose trial is funded by gene therapy company Gyroscope Therapeutics, said: “AMD is the number one cause of untreatable blindness in the developed world.

“A genetic treatment administered early on to preserve the vision in patients who would otherwise lose their sight would be a tremendous breakthrough and certainly something I hope to see in the near future.”

The trial is focusing on dry AMD, which involves a slow deterioration of the cells at the back of the eye.

It affects the central part of a patient’s vision with gaps or ‘smudges’, making everyday activities like reading and recognising faces difficult.

The operation involves detaching the retina and injecting a solution containing a virus underneath.

The virus contains a modified DNA sequence, which infects cells and corrects the genetic defect that causes AMD. Ideally if successful, gene therapy would only need to be performed once, as the effects are thought to be long-lasting.

MacLaren said: “We’re harnessing the power of the virus, a naturally occurring organism, to deliver the DNA into the patient’s cells.

“When the virus opens up inside the retinal cell it releases the DNA of the gene we have cloned, and the cell starts making a protein that we think can modify the disease, correcting the imbalance of the inflammation caused by the complement system.

“The idea of this gene therapy is to ‘deactivate’ the complement system, but at a very specific point at the back of the eye, so the patient would otherwise be unaffected by it, and we hope that in future it will slow down the progression of macular degeneration.”

Surgeons hope the current trial will show they can halt the progress of the condition and preserve what vision patients have remaining.

But in future they hope to trial it on patients with early AMD and so stop the disease before their vision has even started to deteriorate.

MacLaren said: “I would hope that we’ll see a treatment for people with dry AMD within the next few years.”

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