B-eye-onic breakthrough

A new “bionic eye” system has been successfully implanted in a patient in the UK. The recipient was a woman with a condition called age-related macular degeneration, which progressively robs victims of their central vision, greatly reducing their quality of life. Julia Ravey spoke to eye surgeon Mahi Muqet, who performed the implant surgery, to find out more…

Mahi - At Moorefields last week there was a patient who I had implanted an electronic chip into in December and her eye had settled from the operation. She has a condition called dry age related macular degeneration, where she's missing the very centre of the eye in a particularly large area. There isn't any treatment for this, so our clinical trial is looking to implant a device that essentially replaces the light sensitive cells in that part of the eye. The good news was that the electronic chip was working one hundred percent and she actually was very quick to pick up how to use the system.

Julia - How does this bionic eye implant work?

Mahi - It's a pair of glasses that the patient wears. There is a small video camera and it captures about a 50 to 40 degrees field of view. That is then passed from the glasses down to a small pocket computer that sits on the patient's waist, that can be tuned and that then sends a much cleaner image to the glasses. The signals are then beamed using near infrared light inside the eye, directly over the electronic chip. It's about the thinness of a human hair, so it's very, very tiny, and we have these specialised technicians that will help her to use the device and start to scan her visual world.

Julia - Why is it electrical signals that get sent to this chip?

Mahi - It's a bit like solar panels. Out in the desert you may see these cells called photovoltaic cells, that's the technical term, but they're essentially small electrodes; little cells. So, the electronic chip has 300. I think 78 of these small electrodes are called pixels. The near infrared light from the glasses is beamed onto the chip that then charges up these small electrodes to start working. You then have little currents that run through the chip and then the tissue surrounding the chip inside her retina starts to pick up these signals. They start to work and then the network kicks off and all the human function inside the eye helps to take these signals, process them, and they go down the optic nerve to the brain. Imagine you're looking at something, like a letter box, you see it upright, you see it in the right direction - that's to do with all the processing inside the eye. If you didn't have that, it might be lying on its side or upside down. So, what we found in a previous trial is, with the chip, patients are able to see everything in the right orientation -  that's due to the processing. That's the chip working with the cells of the eye.

Julia - Amazing. So, for the cells that I'm missing, it's plugging that gap and allowing you to still patch in the signal to the brain.

Mahi - Exactly, yeah.

Julia - How clear is the vision that you get from it? If I was looking at an eye chart, what line would I be able to read if I had this chip in place?

Mahi - From seeing just shadows, they were able to recognise individual letters and they were also able to scan words. So, if you imagine a patient that has no vision in the centre, is completely dark, they're starting to pick up words and letters. We anticipate that perhaps they could pick up about two lines on the charts, but it's such a small study that now the European study will look at lots of different people in lots of different countries, and then you put all the results together and that will give you a much better and more accurate result from the trial.

Julia - You mentioned that there are trials going on now for using this chip. What more needs to be done before the technology is more widely rolled out?

Mahi - So the first one was what's called 'the first in humans' -  you put the device into patients to actually see if it works. And then once, you know it's safe, you run them over a much larger group of patients and then you follow them up during the study and it's a three year study. The results usually come out towards the end of the study period and, at that point, people are then preparing the next steps. Once we see the results, the next step is being planned.

Julia - It really does sound like life changing technology. How do you think devices like this will change the field of sight restoration?

Mahi - Well, I think for this particular condition, where as you are probably aware, there is no treatment available, if you can restore some form of vision for a patient that's essentially blind in that eye, it can give a significant improvement in the quality of life.