Head space: Finding a way to do 3D surgery on the brain
When Avi Yaron was 26 years old he had a motorbike accident - a day he describes as the luckiest of his life.
As doctors scanned his head to check for damage, they found a tumour deep inside his brain which may otherwise have remained undetected.
And in 1993 the electronic engineering student from Israel was told the mass they had just discovered was nestling close to areas of the brain critical for movement and thought.
He now faced a choice - to have complex, invasive surgery that carried a risk of paralysis, or to find another way.
After a year of searching, Mr Yaron came across a surgeon in New York who removed part of the tumour successfully, and samples showed it was benign. The engineer was then advised to wait until technology had improved enough for the next operation to be less risky.
But for Mr Yaron this was not an option. The possibility remained it could put pressure on parts of the brain as it grew.
He said: "I was young and thinking of starting a family. I could not be passive about this sword hanging over my head."
After five years of seeking out key surgeons and experts in technology, Mr Yaron had the rest of the tumour removed during a conventional operation - with good results.
But this epic search for better surgical options continued to play on his mind. He kept thinking of and experimenting with ways to do brain surgery in a less invasive way.
And over the last few years he perfected a way to do surgery on the brain - in 3D.
Surgery through a scope
In the last 25 years minimally invasive surgery has become commonplace for the relatively easy-to-reach areas of the body, such as keyhole surgery on the abdomen and womb. And more recently surgeons have been able to use scopes (tube-like instruments) in brain surgery too.
During these procedures a thin scope is inserted via a surgically-made or naturally-occurring port in the skin. A camera attached to the end of the scope relays images to a screen for the surgeon to see.
And surgical instruments are passed down the scopes to take samples of tissues or remove masses.
Early versions allowed surgeons to look at 2D images in standard definition, evolving over the last decade into more high definition systems.
Surgeons constantly translate these 2D images into 3D as they operate, much as we do when watching 2D television screens.
More recently 3D technology has become available for certain types of operation. But 3D brain surgery has been a much harder feat to achieve.
In neurosurgery the scopes need to be very small in diameter so they can pass through narrow ports such as the nose.
But most 3D scopes rely on two optical channels - each containing a single sensor. Each sensor collects two separate images that are then mixed together to give the appearance of three dimensions as a user looks at the screen - mirroring the way human eyes see.
It has so far proved difficult to make an instrument small enough that is able to produce the high-quality images neurosurgeons need.
But Mr Yaron says his team have cracked this puzzle by thinking laterally. Rather than copying human anatomy, their scope mimics the compound eye of a bee.
The scope contains a miniature sensor with hundreds of thousands of micron-sized elements, each looking in slightly different directions and mapping the surgical field from many different points.
Using software this is translated into images for the left and right eye. Using this single sensor system, Mr Yaron's company, Visionsense, have produced a scope small enough to operate on the brain.
Shahzada Ahmed from the Queen Elizabeth Hospital in Birmingham who carried out one of the first 3D endoscopic neurosurgical procedures in the UK says: "A bit like going to the movies, Avatar is a great movie in HD but it is an even better one in 3D.
"When I use the scope there is a better appreciation of depth and the pictures feel more real to me."
It also allows him to see his instruments in 3D, which he feels gives him a better understanding of where they are in relation to key parts of anatomy.
A number of studies are now being carried out to see if the 3D approach is better than commonly used 2D high definition systems.
Hani Marcus, a neurosurgeon at the Hamlyn Centre, Imperial College London recently compared the scope to conventional tools, using a model brain and surgeons who are novices to this endoscopic approach.
The study suggests the 3D aspect is beneficial - leading to a faster operation and subjective improvements in depth perception.
But Mr Marcus says it would be a mistake to automatically assume 3D is definitely better than 2D, and thinks further studies are needed.
There are a number of potential problems - surgeons who are already used to seeing 2D may find this approach hard to get used to.
And just as some people don't enjoy watching 3D films and feel slightly nauseous, the same may hold for some surgeons.
But for Mr Yaron, whose scope is now being used in the US and across Europe, this invention is the bright side of an issue that has been playing on his mind for many years.
He says: "If I hadn't had this accident I wouldn't have been able to offer this solution. And I really know how it feels to need options."