This is when super-vision becomes possible. Thanks to the camera, there is scarcely any limit on what an implanted person could see. You could equip the camera with a telephoto or fisheye lens. The camera could swivel. It could receive infrared light (the light that you see in night-vision goggles). So an implantee could see in the dark, or see behind him, or zoom in on a particularly interesting corner of his visual field. (The model for all this, I say with embarrassment, is Star Trek: The Next Generation's Geordi La Forge, the blind character who can "see" infrared and UV light through his special visor.)
Retinal implants, too, could serve as cyborg eyes, though they wouldn't be as sophisticated since they depend on normal light. But you could make a retinal implant in which the sensors respond to a broader range of wavelengths than the human eye does—including infrared light.
Today's implants are crude: Multiplying a 1,000-receptor retinal photo array into a 100,000-receptor array is a daunting problem. Going from 100 brain electrodes to 100,000 is even more difficult.
It's also an invasive process that involves having holes drilled in your head and thousands of wires snaked into your brain. This may be an acceptable risk for a blind person who is eager for newfound sight, but what person with normal vision would choose such a process merely to see in the dark? (Especially since you can mimic the benefits of implants with noninvasive tools such as infrared goggles.) The blind will be the only customers for implants until they become stupendously good.
The final obstacle is the brain itself. It takes a long time to learn to see, and there is no guarantee the brain can retrain itself to master zoom lenses and infrared vision. People with cataracts who regain their sight after surgery sometimes remain "blind" because their brain can't process the new visual stimulus. Rochester's Williams, for one, is unsure the brain is plastic enough to handle vast amounts of new visual information.
Implants that offer some sight to the blind may be available in a decade. Super-vision implants probably won't arrive for at least two decades.
3) The Rainbow Eye
The most audacious supereye would improve us by altering our own genes.
We see colors well because we have "trichromatic" vision: The retina hosts three kinds of "photoreceptive" cones, each sensitive to different wavelengths of the visible light spectrum. The light that enters the eye fires these cones in different amounts, allowing us to see all colors from white to black. (We can't see light at longer—infrared—or shorter—ultraviolet—wavelengths.) In many colorblind people, the third cone doesn't work. The two functioning cones deliver a muddy, narrow band of colors and a much poorer sensory experience. (To get a sense of what "dichromats" see, watch this slide show.)
Many animals, including birds and fish, have four cones, not three. The fourth cone is usually receptive to ultraviolet light, meaning these animals see a whole range of light that we cannot.
Medical College of Wisconsin professor of cell biology Jay Neitz, whose expertise is color vision, recently started to wonder what would happen if humans, like birds, had a fourth cone. Neitz and his wife, Maureen Neitz, who is a professor of ophthalmology at MCW, are working with a species of monkey that has only two kinds of cones. The Neitzes have created a virus containing a gene for a photopigment that the monkeys do not have, and they'll inject this virus into their eyes. If some of the cones absorb the viral DNA, the monkeys should become receptive to light of different wavelengths—the light that the new photopigment senses. The monkeys would then have three kinds of cones. If their brains are able to process the new information, the monkeys might leap from dichromatic vision to trichromatic vision.