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Thread: Artificial Retina

  1. #1 Artificial Retina 
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    Still clunky and expensive, but nevertheless, remarkable technology that's going to give some vision to many.
    http://www.washingtonpost.com/fda-ap...e64_video.html

    Imagine where this might be in ten years.


    Last edited by Lynx_Fox; February 15th, 2013 at 12:28 PM.
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    Huh?
    Is that the right link?


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  4. #3  
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    Didn't you see it?

    No I pasted in the wrong story, thanks for the catch.
    http://www.washingtonpost.com/fda-ap...e64_video.html
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  5. #4  
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    Quote Originally Posted by Lynx_Fox View Post
    Still clunky and expensive, but nevertheless, remarkable technology that's going to give some vision to many.
    FDA approves artificial retina device - The Washington Post

    Imagine where this might be in ten years.
    Funny that I literally was just doing some personal reading on the issue (I feel less guilty when I procrastinate with self edification, when I should be studying) . Anyways, I'm not familiar with that specific device, but from the video it looked like to be an "epiretinal" implant, meaning that it lies on the inside surface on the retina. That type of implant works by directly stimulating the nerve cells that form the optic nerve, and actually, I'm pretty amazed that they work at all given how incredibly complicated visual processing is before it gets to the brain. The photo receptor cells found in the retina do not directly stimulate the nerve cells that eventually relay the signal into the brain, but into cells called bipolar cells, which connect to the retinal ganglion cells that send the signal to the brain. It isn't even that simple though, because the photo receptor cells are connected to each other (indirectly) through cells called horizontal cells, which basically shut off surrounding photoreceptor cells (basically the photoreceptor sending out the strongest signal knocks out the competing cells around it), which helps us make sharper pictures, and I believe detect the edges of objects more easily. Most of the bipolar cells also connect to sells called amacrine cells, which basically function like the horizontal cells, except these cells knock weak signals from bipolar neurons.

    I'm sure it gets more complicated than this (we didn't go any further in my physio class), but the point is that there is a lot of modulation going on well before the signal reaches the ganglion cells, which send it off to the brain, and because "epiretinal" implants, like the one from the original post, work by directly stimulating the ganglion cells, meaning that the initial, multi layered, processing is lost. I suppose that the "primitive" implants we have now, that are very low resolution to begin with, may not feel the resolution limitations that you'd have by simply stimulating the ganglionic cells, but I don't know that it would be possible to get a high resolution image without working through the processing cells.

    The article I was just reading however presents a solution: a "subretinal" implant, which stimulates the processing cells, which then can still process the signal, before it is relayed, by cells, to the ganglion cells. It's pretty ingenious how they got this chip in: they made a retinal detachment, and stuck the electrode on the back of the retinal! They then refilled the eye with oil to force the retina back to the wall of the eye, and there you have it. It even has the advantage of staying put more because it is actually being pressed to the wall of the eye by the retina. The results that they had with this thing were extremely promising: one of the people who received it could pick out the objects on a dinner table, and tell them apart (saucer vs. large plate, spoon vs. knife, a cup, etc.), and could even tell the time (within 15 minutes) by looking at the hands of a clock! The thing is still extremely limited because it needs an external power supply, which is a problem that will likely need to eventually be solved, but the fact that it worked, and worked so well, is just amazing to me.

    Here's a link to the implant I was reading about

    Subretinal electronic chips allow blind patients to read letters and combine them to words
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    Possibly along similar technical lines, some years ago, the Dep't. of the Army demonstrated a device used to make a tank "disappear". Equipped with thousands of sensors, which transmit and display the actual view seen behind the tank, in front of it, thus the viewer of the tank sees only the backdrop of whatever is behind it. Clever, expensive, ..... usefull? Make a foot soldier "disappear", for example.

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  7. #6  
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    Its a really a milestone in the field of Medical Science.Its a bit costlier but in future its kind of mobile phones and people from all level can purchase it.
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