Gene Therapy Cures Color-Blind Monkeys

SpuriousLogic writes "After receiving injections of genes that produce color-detecting proteins, two color-blind monkeys have seen red and green for the first time. Except in its extreme forms, color blindness isn't a debilitating condition, but it's a convenient stand-in for other types of blindness that might be treated with gene therapy. The monkey success raises the possibility of reversing those diseases, in a manner that most scientists considered impossible. 'We said it was possible to give an adult monkey with a model of human red-green color blindness the retina of a person with normal color vision. Every single person I talked to said, absolutely not,' said study co-author Jay Neitz, a University of Washington ophthalmologist. 'And almost every unsolved vision defect out there has this component in one way or another, where the ability to translate light into a gene signal is involved.' The full-spectrum supplementation of the squirrel monkeys' sight, described Wednesday in Nature, comes just less than a year after researchers used gene therapy to restore light perception in people afflicted by Leber Congenital Amaurosis, a rare and untreatable form of blindness."

Re:Cerebral achromatopsia

[sumthinboutjesus]

To summarize for those who don't want to wade through the wikipedia article, achromatopsia is color blindness resulting from damage to the cortex, the outer layer of the cells in the brain that are generally responsible for all the higher-order processing of the sensory information our nervous system collects. Essentially, this means that your eyes are still functioning normally, but your brain is no longer able to interpret the signals properly; this is normally due to brain damage as result of loss of blood flow, often from a traumatic injury or stroke etc, although there are many other causes, some of which are unknown (idiopathic). This is certainly a different cause of color blindness, but I'm unsure as of why it's being discussed here because the treatments talked about in the article would only correct defects on the functional components of the eye. Correcting a problem in the cortex through a medical treatment is something that is most likely a good ways into the future; it's much more likely that your brain will spontaneously reroute the functional processing to a different undamaged part of the cortex and as a result recover full or partial color vision. If that doesn't happen, which often it doesn't, then it's unlikely that the problem will be fixed.

Re:biotech rocks

[Miamicanes]

> Could you imagine being able to see halfway down the IR spectrum, or well past UV on the other end

IR might be do-able, but UV is almost structurally impossible for the human eye to meaningfully view. The spectral peak of "blue" cones is actually closer to violet than blue. If you look at a sensitivity curve for human blue cones, you'll notice that its peak is just slightly above violet, and its lower third is simply chopped off or attenuated away. The problem is the cornea -- it blocks most UV light. What the cornea doesn't block, the fluid inside the eye absorbs and scatters. There have been reports that people who've had cataract surgery are able to perceive UV as hazy, diffuse "purplish-yellow" light. The idea that something can be purple and yellow is strange, but not as crazy as it sounds when you consider that the color we call "purple" is NOTHING like spectral violet, and is actually an artifact of human vision caused by a nonlinear slope in blue sensitivity. There's a tiny area where the upper end of blue overlaps with the lower end of red, with a small ripple in blue that introduces just enough error in that region to make purple possible.

There's another problem: chromatic aberration. Ever notice that you can make a fake 3d-like pic using pure red and pure blue, so the blue parts seem to be floating in space compared to the red? That's chromatic aberration at work. The cornea can only focus light from a relatively narrow band. The lower you go, the less-focused the light would be. Similar distortion would become problematic in the infrared range, though not as quickly as at the blue end.

Re:Next step: Tetrachromatism

[Miamicanes]

> So? Glasses to filter out all but visible light (today's visible light) should be trivial. Just like those blue & red 3D glasses.

Women believed to be tetrachromatic don't see light trichromats can't see... they recognize two variants of "green" as being different, the same way green and red are different to you. If you were genuinely tetrachromatic in the sense the women are believed to be, TV, film, photographs, and printed images would almost ALWAYS look like shit to you, because the "green" would be "wrong" in ways you couldn't really explain.

Here's an example: suppose you were a trichromat, living in a world where 94% of the population couldn't distinguish between red and green, and for all intents and purposes "yellow" was just a darker or brighter shade of red/green. Color film wouldn't be based on red, green, and blue... it would be based on blue and yellow. Your RGB monitor would be a BY monitor. To everyone else, the whole idea of "RGB" would be silly, because they could get the exact same image quality from just blue and yellow. You'd be the unfortunate person who kept babbling about there being a difference between "red" and "green", and that they were somehow different from the color everyone else knew as "yellow". Anyway, getting back to the example, a tetrachromatic woman wouldn't want RGB... she'd want RGgB, where "G" and "g" were slightly different frequencies of green. An RGB monitor to a tetrachromat would look just as artificial, fake, and bad as a Blue-Yellow monitor designed for deutranopes and protanopes would to you.