Science News

Repairing Eyes With Plastic

Thu, 21st Mar 2013

Dave Ansell

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Dave -  Scientists from the Italian Institute of Technology in Genoa have managed to stimulate a retina just by using a piece of plastic and some light.  So, there are quite a lot of diseases which cause degeneration of your retina, things like retinitis pigmentosa and macular degeneration which are very common especially in elderly people and whereby, your retina can't detect light, so you suddenly go blind.

Chris - So, critically in those conditions, the photoreceptors that converts photons into nerve signals, they go, but the actual retina parts that give our eyes to the optic nerve going back to the brain, they're still there.

Dave - So, the wiring is still there. So, the idea is, if you can somehow put the signal into that wiring, you could still see.

So, what they’ve been doing is they’ve been dealing with a series of plastics which when you shine light on them, they can produce voltages. And they’ve got a sheet of this plastic called p3ht and they’ve discovered that if you put a piece of retina on the top in a kind of sort of salty liquid electrolyte on the surface, and then you shine a light at the plastic, you get enough voltage produced by the plastic to trigger these cells. And depending on how fast you shine that light, if you shine it at 1 hertz so you're flashing on and off once a second, about 95% of the time when you turn it on, you trigger nerve cells. If you're trying it at 20 hertz, 20 times a second, it gets a bit less good, 65% of the time. So, it’s not perfect, but it does show that just with a very, very simple thing, just a sheet of plastic and on top of the retina, you can actually produce signals which should then, if the retina was still attached to the rat, mean the rat could see.

Chris - Does enough light go into the eye to drive this thing, were you to implant this into the eye as a sort of implant?

Dave - So, at the moment, there's enough light getting there. It will be stimulated by full sunlight so you'll be able to see in full daylight. But as soon as you got inside and lower light levels, it’s not very good. So, as it is at the moment, it probably wouldn’t be ideal solution, but that’s something which I'm sure they're looking into developing an increasing sensitivity and increasing the effectiveness of the stimulation.

Phil - What I was going to say, Dave is you said they have to put a sort of salty solution on the top. Is the eventual idea to have that supplied by the fluid inside the eye?

Dave - Yes, so you're essentially filled with salty solutions and so, I think the idea is and what they'll be looking at doing next is basically just taking pieces of plastic, putting it in the eye of a blind rat and seeing whether the rat can then detect light. It has the advantage over other systems where they've actually used complex electronics in that, it’s a sheet of plastic. It doesn’t need any power. It doesn’t produce any heat and this plastic also seems to be fairly biocompatible. They're certainly growing nerve cells on it for 20 days and nerve cells seem perfectly happy. So, I mean obviously, it’s a long way to actually use it in humans, but it’s looking quite positive.

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