In people with hereditary retinal diseases like retinitis pigmentosa, the eyes’ photoreceptors, or light sensors, degenerate slowly over time, eventually leading to blindness. While these people are unable to see, the rest of their visual pathway remains intact and functional. Researchers in Germany now have a way to work around this roadblock by introducing an implant to take the place of the broken photoreceptors and restore some level of communication directly with a patient’s visual pathway.
The researchers implanted a tiny electronic device under the retina of patients to take the place of their non-functioning photoreceptors. The implant is only about a third of an inch squared—the size of a Chiclet—and converts light into electrical signals. It is powered wirelessly via a battery pack attached behind the patient’s ear.
Our ability to see depends on two factors: light-sensitive rods and cones in the retina, and the nerves that transmit signals from these cells to the brain (along with the brain itself, of course). When the rods and cones die, which can occur as the eye ages or in the retina-damaging eye disease retinitis pigmentosa, the nerves can sometimes still function—if they have a new, working sensor for light. To replace the rods and cones, previous treatments have used electronic implants, which require surgery, or gene therapy, which relies on injections deep into the eye. But in a new technique, all it takes to restore vision—at least partially—is a much less invasive injection of the chemical AAQ.
With glasses, contacts, and LASIK surgery, most of us nearsightedness folks don’t have to worry about squinting at the blackboard anymore. But the sheer prevalence of nearsightedness, or myopia, among Asian schoolchildren (in Singapore, China, Taiwan, Hong Kong, Japan, and Korea) is stunning: 80 to 90% according to a recent review in the journal Lancet. In comparison, that number is just 20 to 30% in the UK. Myopia has also been on the rise in both Asia and Europe over the past few years.
While there are genes linked to myopia, its rising prevalence in both continents points to environmental causes. Namely, kids are spending more time hunched over screens and books instead of playing outdoors. In myopia, light coming into the eye can no longer focus at the retina because the eyeball has become too long. A body of research in humans and animals suggest that reading at close distances and lack of bright sunlight could cause elongated eyeballs.
Why’d the zebra evolve its stripes? Perhaps because stripes seem to keep off horseflies, a new study suggests. There’s good evolutionary reason to escape the ravages of horseflies, at least for horses and their relatives; though flies are just annoying pests from the human perspective, horsefly-bitten horses can grow skinny and have trouble producing milk for their young. And as soon as baby-making is affected by something in the environment, adaptation isn’t far behind.
Other research has shown that horseflies prefer to land on black horses instead of white, which got Gabor Horvath, author of the recent study, thinking about how they’d react to black-and-white specimens, such as zebras. Of course, actual zebras can be hard to experiment on, as The Economist notes in an article on the research:
[Real zebras] insist on moving around and swishing their tails. The team therefore conducted their study using inanimate objects. Some were painted uniformly dark or uniformly light, and some had stripes of various widths. Some were plastic trays filled with salad oil (to trap any insect that landed). Some were glue-covered boards. And some were actual models of zebra. They put these objects in a field infested with horseflies and counted the number of insects they trapped.
The strangest thing about this Chinese boy’s light blue eyes is not their color. It’s the purported fact that he can see in the dark. His eyes are just like cat eyes, glowing blue-green when you shine a light in them, says this clip from China’s state-run English TV channel. The boy can catch crickets in the dark without a flashlight and even completes a writing test in a pitch-black stairwell. True, or too good to be?
Natalie Wolchover at Life’s Little Mysteries has rounded up some experts and their collective reaction seems to be, “Hmm…” (It doesn’t help that this video has been posted on YouTube under the name, “Alien Hybrid or Starchild Discovered in China? 2012.”) One possibility they consider is whether the boy has a mutation that produced something like a tapetum lucidum, an extra layer of tissue that helps cats see in the dark. James Reynolds, a pediatric ophthalmologist at State University of New York in Buffalo, puts a stop to that idea:
Bionic contact lenses—which would display navigation data, personal emails, or any other sort of info superimposed on the world before your eyes—have long been mainstays of science fiction. Over the past several years, researchers have been working to make the tech real-world ready, striving to find solutions to the energy, size, safety, and image-quality problems that come up when you’re trying to fit a tiny integrated circuit into something transparent that sits on an eyeball.
Now, University of Washington researchers and their Finnish colleagues have made the first functioning bionic lens: a prototype with a single LED pixel, which could be safely worn by rabbits in the lab. (The image at right shows a rabbit wearing an earlier version of the lens, which contained a circuit but no light-emitting components.) Radio frequency energy emitted from a nearby transmitter and picked up by a circular antenna a fifth of an inch in diameter, printed on the lens, powered the electronics. The transmitter supplied adequate energy from three feet away when the lens was sitting in a dish, but had to be less than an inch away when the lens was placed on a rabbit’s eye, since tissues and fluids in the body interfered with reception. Since light from such a lens would be too close for the human eye to focus, the researchers made a separate contact composed of an array of smaller, flatter lenses, which would sit on top of the bionic contact and focus the light.
The colors that letters and numbers appear to a synesthete
What’s the News: For most of us, our senses stay relatively separate: that is, we hear what we hear and see what we see. People with synesthesia, however, actually see words as colors, taste a particular flavor when they hear a familiar song, or experience other strong, automatic linkages between senses. The neurological underpinnings of the condition—how the brain connects two usually distinct senses—have remained a mystery. But researchers have now found a possible cause, they reported yesterday: neurons in the area responsible for the second sensation, such as the color that goes with the word, may be unusually excitable.
What’s the news: In a study published last week, researchers showed they could reconstruct video clips by watching viewers’ brain activity. The video of the study’s results, below, is pretty amazing, showing the original clips and their reconstructions side by side. How does it work, and does it mean mind-reading is on its way in?
What’s the News: Humans are eerily good at sifting the visual wheat from the chaff—just think of our penchant for word searches, Easter egg hunts, and lushly animated first-person shooters.
But how good are we really? To test the limits of these abilities, in a recent study neuroscientists gave subjects extremely difficult, high-speed Where’s Waldo-type search tasks studded with red herrings. But again and again, subjects found what they were looking for, leading the team to report that humans operate at a near-optimal level when it comes to visual searches—a skill that likely came in handy in our evolutionary history.