Thursday, June 4, 2009

Fix for My Blindness Not Far Off?

This technique, which involves lining a contact lens with a patient's own cultured stem cells, probably won't work for my condition, but it sounds like a step in the right direction.



SuiginChou said...

Not to crush your hopes or anything, so I'll ask a quick question first: how much LIGHT would you say you can see out of your right eye (as compared with your left eye)? Answer that first. :\

Note: I'm just talking light. As in ... when you close your good eye and, eyelid closed, face a blindingly bright source of light. Defining your good eye's perception of that red-orange-yellow color it sees as "1.00", what percent would you say your bad eye sees light at? 0% 100%? or somewhere in between? This has nothing to do with the acuity with which either eye sees light, i.e. it has nothing to do with me asking if you can see shapes, colors, pixels, etc. I'm JUST concerned with how bright eye #1 is compared with eye #2.

Jay said...

I can't see any light and the eye is undeveloped/malformed. This therapy is more for damaged but once-working eyes. But I got to think it's a step in the right direction.

SuiginChou said...

If you can't see any light at all, then I'd say you've got to wait a while longer. :(

One of the most famous research projects in modern American medicine was the experiments performed on stray cats and their kittens by Drs. Hubel and Wiesel. In one of many experiments which would be 100% illegal to conduct today, they sewed a newborn kitten's eye shut (only one of them), euthanized the cat n many weeks after birth, and sliced the cat's occipital cortex into thin layers for histological studies. Long story short, they found (comparing these against normal euthanized cats and double-blind euthanized cats) evidence suggesting that during a critical period in the newborn, the brain will assign x% of visual cortex to an eye; that for people with two equally-powerful eyes the value for x1 is 50% and for x2 is also 50%, and that for kittens who had their one eye sewn shut the ratio was more like 80:20 to 99:1. What Hubel and Wiesel discovered was that, once the stitches were removed and the cat was allowed to use its 100%-normally developed eye (obviously they did this to non-euthanized cats), the cat still was essentially blind in that eye. They were able to prove (through rigorous studies involving placing electrodes in living cats' brains as well as sectioning euthanized cats' brains) that the cats' sewn-shut eyes were indeed receiving light just fine, that the retina cells were transmitting it to the optic chiasm, that thee optic chiasm cells were transmitting it to the occipital lobe's visual cortex, etc. But that at the level of the visual cortex itself, the signals were hitting a brick wall. Or rather, they were like the train in BTTF 3 -- going down a track that leads to a "Bridge Out!" cliff. The brain's visual cortex had (disproportionately) been allotted to what the developing brain in the neonate assumed was "my only working eye."

None of this means you ought to lose hope or give up or whatever. A, cats aren't humans, however similar we are indeed. B, there's a hell of a lot to be said for neural plasticity, i.e. if a blind man can actually see (and I do mean see see) the world via an apparatus that converts light entering a camera into pressure applied to his back, then I think you could take your never-before-used eye and get your brain to pay attention to it. :p :)

But it's a ways off. :( Much more so than a simple cornea transplant.

SuiginChou said...

Just to be clear, Hubel and Wiesel didn't section cats brains too often. For better or worse (you decide), their more common practice was to keep the cats alive and to manually insert electrodes into the cats' brains and register the change in detected electrical potential as a function of both time and of the presentation of certain visual stimuli. Indeed, this method (of insertion of live wires into living cats' brains) was how the two men proved the existence of what we now know to be the so-called visual columns of the brain. It's hard to explain in words and very easy to explain with a drawing, so if you want to know what "visual columns" means, search for that + "Hubel and Wiesel" + "cats" and you should get good stuff.

As a highly-biased cat lover, I find these experiments appalling. But I must confess that if I had to choose between inserting live electrical wires into a less sapient animal's brain and condemning people to any one of the many brain disorders or diseases we're fighting uphill battles against, I'd pick the former. As for what they did ... I dunno. I don't like them as men (terribly cruel to cats :( ), but what they found is really ingenious and invaluable to our understanding of the visual cortex. It's quite the "Nazi medicine" dilemma, indeed, only less extreme (cats vs. fellow human beings) but still too extreme for my blood (cats vs. "brainless critters" like crabs or something).

Anonymous said...
This comment has been removed by a blog administrator.