Drug shown to improve sight for patients with inherited blindness
26 July 2011
A clinical trial led by Newcastle University has shown that the drug, idebenone (Catena®), improved the vision and perception of colour in people with Leber's hereditary optic neuropathy (LHON), an inherited condition that typically begins in young adulthood. People with LHON, who can see normally until onset of the condition, lose the sight in one eye and within three to six months lose the sight in their other eye.
In some severely affected patients, such as those who were unable to read any letters on an eye chart, the treatment with idebenone resulted in a marked improvement in their vision. In 9 out of 36 people with LHON taking idebenone, vision improved to the extent that they were able to read at least one row of letters on the chart. None of the 26 people who were taking the placebo improved to the same extent.
Inherited from the mother, and mainly affecting men, LHON is caused by damage to the mitochondria in the eyes - the 'batteries' that power their cells. It is one of the most common causes of inherited blindness and is thought to affect around 2000 people in the UK, 10 000 in Europe and a further 10 000 in the USA.
Professor Patrick Chinnery, a Wellcome Trust Senior Fellow in Clinical Science at Newcastle University, who led the trial, said: "This is the first proven treatment for a mitochondrial disorder. We have seen patients who couldn't even see an eye chart on the wall go on to read the first line down - and some even attempted the second line. For these patients, it can mean a vast improvement in their quality of life."
Today in an article about the trial in the journal 'Brain', the authors describe how people with LHON were recruited from hospitals in Newcastle (UK), Munich (Germany) and Montreal (Canada) for a double blind trial. Participants were either given idebenone for 24 weeks or a placebo.
At the end of the six months, some people with LHON who were treated with idebenone had improved vision; this is the first time a successful treatment has been found. The greatest improvement was seen in those who had deteriorated in one eye more than the other.
Professor Chinnery explained: "We saw most progress in people who had better vision in one eye than the other - this tends to indicate that they are at an earlier stage of the condition. While we know that their vision is not what it once was, we also know that this treatment can dramatically improve their lives - some were able to move around more easily or even see family photos again.
"We are hearing from patients that they still have improved vision, even though they are no longer taking the drug, but we would like to verify this and study the effect further. There may also be a case for offering idebenone from the first moment that LHON is diagnosed - preferably before any symptoms are shown - and a further trial would ideally examine this."
Mike Scholes, 58, an ex Royal Navy pilot, lost the sight in his left eye in just five days. Within seven months, the sight in his right eye also started to deteriorate and he was diagnosed with LHON. Shortly after, he signed up to take part in the trial. After just a month and half, he started to see an improvement in the area of vision affected in his right eye.
He said: "Having Leber's hasn’t stopped me enjoying life to the full -I run marathons with a guide, I've hiked to the North Pole - but the noticeable improvement in my vision means daily life is easier. I can use a computerised viewer to help me read, I can get dressed without having to use a detector for the colours of clothes and while initially I couldn't even see the eye chart, now if I get really close to a street sign I can read it."
Idebenone penetrates into the mitochondria and is thought to absorb toxic free radicals and enhance mitochondrial function. Previous research had provided anecdotal reports of improvements in vision, but this is the first time it had been put to the test in a clinical trial. The drug company that sponsored this trial, Santhera Pharmaceuticals, is now seeking marketing approval from the European Medicines Agency for it to be offered as a standard form of treatment.
Reference
Klopstock T et al. A randomized placebo-controlled trial of idebenone in Leber's hereditary optic neuropathy. Brain 2011 [epub ahead of print]
Image: Mike Scholes, a person with LHON, hiking to the North Pole.
