Bionic Cat Eye Implants Aid Blindness Research

docinthemachine writes with news of felines getting human retinal implants. The cats were afflicted with a version of retinitis pigmentosa, a disease that also blinds humans. The implants are 2-millimeter-wide chips surgically implanted in the back of eye. Each chip's surface is covered with 5,000 microphotodiodes that react to light, sending electric signals along the eye's optic nerve to the brain. The article makes clear that the implants don't allow the cats to see — what they get is impulses of light. The hope is that the electrical activity in the optic nerve will encourage new retinal cells to grow. The article notes: "The chips, which provide their own energy, have shown encouraging results in clinical human trials, in some cases improving sight in people with retinitis pigmentosa or at least slowing the disease's development. Narfstrom said chips have been implanted in 30 people."

Comments

Question for the experts

[Control Group]

I'm not a neurophysiologist, so perhaps the answer to this is obvious, but I've got a question: if the chip can detect light impulses and stimulate the optic nerve, why does there need to be cellular regeneration? Given time, wouldn't the brain learn to interpret those signals as optical input, just like it did with the rods and cones the eye was born with? Obviously, the "grain" and responsiveness of the photodiodes is much worse than that of the Mark I eyeball, but it's still a path for light information to get to the brain. The resultant "sight" would be far inferior to natural vision, but also better than blindness.

The human brain is nothing if not adaptable; I would think it could learn to use anything which was able to pump signals onto the optic nerve.

Or am I way off base?

Re:Question for the experts

[Raindance]

I'm not a neurophysiologist, so perhaps the answer to this is obvious, but I've got a question: if the chip can detect light impulses and stimulate the optic nerve, why does there need to be cellular regeneration? Given time, wouldn't the brain learn to interpret those signals as optical input, just like it did with the rods and cones the eye was born with? Obviously, the "grain" and responsiveness of the photodiodes is much worse than that of the Mark I eyeball, but it's still a path for light information to get to the brain. The resultant "sight" would be far inferior to natural vision, but also better than blindness.

The human brain is nothing if not adaptable; I would think it could learn to use anything which was able to pump signals onto the optic nerve.

I'm not a neurophysiologist either (perhaps BWJones will chip in here) but here's my two cents.

The chip can detect light impulses and stimulate the optic nerve, as you say- the article even mentions "We're placing it right where the photoreceptors are and if they're lacking, this is supposed to replace what they're doing." So why isn't this plug-and-play with our eyes- why do we need these implants to work via cellular regeneration?

Put simply, there is a limit to the eye's plasticity during maturity-- if these cats had been born with these chips implanted in their eyes, they could probably use them to see in some fashion (at lower quality, as you note). However, they're so far out of spec with the type of input given by normal photoreceptors (with which they're currently operating in parallel) that the mature eye/brain calibrated to normal photoreceptors simply tends to screen these inputs out.

Someday we'll understand the "spec" of the eye well enough for tech that plugs-and-plays with the rest of the eye, but currently we're limited to promoting the body's own healing, or, in cases of total blindness, just bypassing the eye and just stimulating the visual cortex directly (at very low resolution).