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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."
> 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.