From the front, Canon’s latest retina-imaging camera looks every inch the hi-tech hospital machine. But look past the small, curved shelf where you rest your chin and you’ll notice that the operator is pressing the shutter of what looks suspiciously like a very standard, digital SLR camera.
These machines take images of the back of the inside of your eye and are used to diagnose conditions such as glaucoma. The retina is also the only place in the human body where blood vessels can be directly observed so detailed pictures can also help doctors spot the early signs of diabetes and hypertension. A very clear, high resolution image is essential so that doctors can detect the exact formation of blood vessels and tissues in an area just a few millimeters wide.
In fact, the camera in these retina imaging machines is a Canon EOS 50D, a consumer camera that you can buy for about £800. This camera has a 15.1 megapixel sensor, and so produces pictures that have a perfectly high enough resolution to show the required details. EOS cameras also have a well-balanced system of lenses, mirrors and filters making them an excellent starting point for very specialised cameras.
So could you take the 50D off the back of the retina imaging machine, attach a lens and start taking pictures? Well in theory you could, explained the operator who photographed my retina at Canon’s expo show last week. “Except you’d end up with really rubbish pictures.”
The EOS sensor has been specially adapted and the infrared cut-off filter found in many photographic sensors has been removed. The resulting camera can handle multiple kinds of retina imaging, including in a high quality infra red observation mode, color fundus photography, and digital filtered images for red-free and cobalt photography. Without this infrared cut-off filter, however, the sensor would struggle in normal light conditions so I wouldn’t recommend trying to smuggle this camera home if you ever have your retina photographed.
We’re fairly used to the idea that specialised technology sometimes filters down into every day objects; NASA’s inventions – from cordless power tools to the design for shock-absorbing trainers – turn up all over the place.
What is more remarkable is the idea that consumer products are now sophisticated enough to send technology back in the other direction so that one man’s relatively standard digital camera becomes another man’s hi-tech machine.
Telegraph Uk