Slashdot Mirror
Silicon Retinal Implants Are Here
Ant was one of the first to write with this news: "CHICAGO -- Illinois scientists said Friday they have successfully implanted
silicon microchips beneath human retinas for the first time, a procedure that holds promise for millions of people with failing eyesight. Earlier this week, three patients who lost almost all of their vision from retinitis pigmentosa -- a hereditary condition in which the retina gradually degenerates -- became the first people to have an Artificial Silicon Retina implanted."
And there's also been the headlines recently about that plastic surgeon that placed breast implants into the ass of some women that wanted a bigger but. What's next, installing optical implants into someone's ass?
kwsNI
having pretty horrible vision myself, this surgery all sounds very interesting. my optomitrest recently commented that my eyesight was getting worse more quickly than anyone's he'd ever seen before-- this bothered me. so what i'm left to wonder is, how much will this damned surgery cost? because i'm sure my insurance will find a way around paying for it... and when that happens, will only the very rich be able to afford good eyesight???
i feel as if right now i am at a defecit to the seeing population of the world... what happens when the rich people are the only ones who can afford to "fix" their bodies so they function properly???
grizzo: totally insecure, but very convenient.
This has some pretty cool implications for virtual reality: if scientists can figure out how to hook into the vision nerves, and this looks like a great start, we could soon "plug in" matrix style (although hopefully without the agonising pain) to external visual inputs.
The implant itself, while the benificiaries seem to be from only one kind of eye problem for the time being, seems to be an indicator of a coming rush of "bionic" implants that will change the way humans live, or at least wealthy humans. I seem to remember reading many science fiction books that project this future...
I for one am looking forward to reading slashdot by subvocalising (Andrew Wiggan style) a command to the implanted screen in my eye, and seeing it as a "full screen" 3d panoramic view, where the full screen is just that... an all encompassing virtual view.
tsf.
Just imagine a beowulf cluster of these!
Oh, never mind I just imagined it and it wasn't that exciting...
If voting were effective, it would be illegal by now.
It's a photoelectric cell that generates electrical stimulation similar to the kind that a retina would on being struck by light. This is NOT a microchip. There is no processing or logic involved.
Mmmm.. Donuts
There's more to vision than a functioning eye. The brain's got to know what to do with it! I've had severe amblyopia in my left eye for most of my life.. not really a retinal problem, but the doc told me that even if I underwent surgery to correct the physical problem, the chances of the nerve connections regenerating are slim. If the condition that this chip is treating is the result of a gradual degeneration of the retina, wouldn't the nerve connections gradually degenerate as well? Guess we'll have to wait and "see" how this procedure works out..
seanmeister
The article states that this procedure is only for retinitis pigmentosa, but in the end, it is not a treatment for RP, but an early biocompatibility test. RP is only a useful physiological test bed that renders the patient blind over large areas of the retina, while leaving most of the retinal structure intact. The patient was undoubtedly a research volunteer, and was aware of all this, and should probbaly more properly be coinsdered a 'subject' (but I hate calling patients that).
.phy-astr.gsu.edu/hbase/vision/rodcone.html
As you probably recall from elementary school, there are two types of receptors in the eye. Rods handle B/W vision, are more sensitive to light, and are responsible for night and peripheral vision. Cones handle color vision, and are only found in the central areas of the visual field, especially the area of best vision in the eye, fovea centralis. (not to be confused with a nearby region of *no* vision, the macula lutea or 'blind spot' where the optic nerve enters the retina). Simple layman diagrams and links to useful concepts (but not *absolutely* accurate) can be found at:
http://hyperphysics.p hy-astr.gsu.edu/hbase/vision/retina.html
http://hyperphysics
Here's a good anatomical overview of the eye
RP is a group of genetic diseases which cause the rods to degenerate. about ten different mutation have been linked to forms of RP, which can be dominant, recessive, or X-linked. Initially, the patient loses their peripheral vision, beginning in a single region, then gradually spreading. The fovea centralis is the last region to be affected, if ever, because there are few rods in the fovea. It is not clear if loss of sharp central vision is due to 'pure' RP at all, since mutations in some 'RP' genes can cause macular degenerations or other retinal conditions. It appears that the loss of central vision is dependent on the individual's particular mutation.
The retina is laid out in layers, and in very different way that you might imagine. The photo sensors are in the *back* of the retina, and in front of them are several layers of neurons that allow the sensors to integrate (share info between nearby sensors, etc) and in front of that are the blood vessels a snd the neurons that go from the interneurons into the optic nerve, etc. Light passes through all these layers before hitting the rod and cone sensors. The only things that are 'behind' the sensors are the pigmented (choroid) layer, a black layer that absorbs all leftover light to keep it from bouncing around the eye; and the sclera, the tough "white of the eye" that provides support.
[Slides and images]
[Good slide, exlanations, links, but a bit technical]
So why use this implant in RP? Well, by prying apart the layers of the retina as described, the sensors can be placed where the cones used to be, and with a bit of luck, the overlying layers of interconnecting neurons will remain intact (they are presumably unaffected by the rod-destroying mutations, since 'cone' vision is preserved in RP) All this is done in the periphery of the eye, away from the delicate Fovea and macula. Here it can be tested, through the (largely) intact eye, without significantly affecting the patient's remaining natural vision (though there's always some risk)
This implant links into the web of interneurons in the retina, instead of having to be connected to the optic nerve as the native rods and cones do. You can see how this is easier than trying to do delicate neurosurgery on the optic nerve, and then re-training the patient's visual cortex. This is the most 'natural' process for th patient, since all position info is preserved and the preprocessing of the retina is present (ther preprocessing has two purposes: feedback to nearby sensors, which is lost in man-made sensors, and pre-processing of the visual impulses, which is preserved)
However, a low resolution 'pinhead' sensor on the periphery won't help an RP patient at all. In fact, patients sometimes find patchy remnants of peripheral vision distracting and annoying. Clearly this is not a treatment for RP but an early stage biocompatibility test for later work (that is more likely to be useful in other conditions).
Here's a review article on progress and challenges in similar subretinal implant technologies
(Disclaimer: I published some research on retinal layers as an undergrad, but that was almost 20 years ago, and before I went to medical school)
If you can go to bed, knowing you did a valuable thing today, you're very lucky. If you can't... it's not bedtime
Among (far too many) other interests, human perception is a major fascination of mine. I had the good fortune to take a perception class last quarter, and we studied much of how the visual system functions. Here's a bit of what's going on:
Most of vision is not, in fact, provided by the whole of the retina. The fovea, which is (optimally) the direct point of focus for light reaching the back of the eye, is also about the size of a pinhead--yet, it contains about half of our photoreceptors. We actually see very little of a scene at any given time; our eyes essentially "paint the fovea" with a strip of images in normal viewing and jitter around for focused viewing, such that the brain has a large amount of content to stitch together and the photoreceptors/neurons don't tire from lack of signal change.
We filter out constant signals automatically, like the hum of your PC you just noticed when I brought it up.
What my major concern is, I can't particularly figure out where this implantation is taking place, in terms of thickness. The nerves that actually carry the visual system through the optic nerve to the striate cortex are in front of, not behind, the existing photoreceptors. You've got two layers of nerves sitting in front of the photoreceptors, and they're placing the chip behind? This makes me wonder whether they're trying to stimulate or amplify existing photoreceptor activity--which leads to all sorts of questions regarding intensity, variance, signal matching, and so on. Did they solve the electrical potential problem? Supposedly you can't interface an electrode with a nervous system for too long, or you kill the nerve. Maybe the size of the implant helps here too--it's not impossible to imagine that this little fleck of a chip is being placed among photoreceptors?
Does anybody know more about this system? I'm getting really burnt on stories about interesting tech with no quality links. *sigh*
Yours Truly,
Dan Kaminsky
DoxPara Research
http://www.doxpara.com
Here's the original press release: /depts/paff/opa/releases/retinas_advisory.html
http://www.uic.edu
And the company mentioned in the PR, Optiobionics, has a FAQ (which addresses questions of resolution and perception quality for potential patients... in short, they're not sure yet, but it won't be all that great) here.
:wq