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Eye Doctors Still Use This 100-Year-Old Test for Color Blindness

You may have seen them at your ophthalmologist's office: large circular diagrams made up of colored dots. People with normal vision are able to discern a number among the dots of contrasting colors. People who are color blind might see only a field of spots.

These elegant, deceptively modern drawings were published 100 years ago by a Japanese ophthalmologist, Shinobu Ishihara. Thanks to the designs' simplicity and diagnostic accuracy, the Ishihara test is still the most popular and efficient way to identify patients with color vision deficiencies.

Born in Tokyo in 1879, Ishihara studied medicine at the prestigious Tokyo Imperial University on a military scholarship, which required him to serve in the armed forces. After graduating in 1905, he worked for three years as a physician specializing in surgery in the Imperial Japanese Army, and then returned to the university for postgraduate studies in ophthalmology. In his research, Ishihara focused on identifying and recruiting soldiers with superior vision, thereby increasing the overall effectiveness of the military. And that became of prime importance to Japan beginning in 1914.

As World War I spread across Europe, Asia, and the Pacific, the Japanese army asked Ishihara to develop a better way to screen draftees for color vision problems. The most popular method at the time was the Stilling test, invented by German ophthalmologist Jakob Stilling in 1878 as the first clinical color vision test. (Previous tools had asked patients to identify the colors of wool skeins or illuminated lanterns—useful skills for sailors and railway conductors, but an imprecise method for diagnosing vision issues.)

"Though popular, 'the Stilling' retained a distinctly 19th-century flavor, more treatise-like and less diagnostically incisive," according to Eye magazine.


Shinobu Ishihara
Wellcome Images // CC BY 4.0

Japanese army officials requested a new diagnostic tool that was easier to administer and interpret. The test Ishihara began to develop was based, like Stilling's, on the principle of pseudo-isochromatism—a phenomenon in which two or more colors are seen as the same (or isochromatic) when they're actually different. A person with normal vision could easily see the difference, while people with red-green deficiency, the most common form of color blindness, would have difficulty distinguishing those two opposing colors. Those with blue-yellow color blindness, a less common type, would have a hard time discerning reds, greens, blues, or yellows.

Ishihara hand-painted circular designs comprised of small dots of different areas and colors so that variations in the design could be discerned only by color and not shape, size, or pattern. Hidden in the field of dots was a figure of a contrasting color that people with normal vision could see, while those with deficiencies could not. Other plates in the series were designed to show figures that would be visible only to people with deficiencies. When physicians displayed the diagrams, patients said or traced the visible figure within the circle without needing to use ambiguous color names, which standardized the possible results.

The earliest sets of Ishihara plates, produced in 1916, were reserved exclusively for the army's use and featured Japanese characters within the diagrams. In 1917, in an effort to sell the series internationally, Ishihara redesigned it with the now-familiar Arabic numerals and published a set of 16 plates as Tests for Colour Deficiency.

The tests were adopted throughout the world beginning in the early 1920s, and eventually grew into a set of 38 plates. But their popularity almost led to their undoing. Unauthorized publishers printed their own version of the plates to meet demand, throwing the accuracy of the diagnostic colors into doubt. "The plates have been duplicated along with an easily memorized key by cheap color processes in the tabloid press, and exposed in public places, reducing the fifth edition [of the collection] to a parlor game," one psychologist warned in the Journal of the Optical Society of America in 1943.

Despite those obstacles, the tests proved indispensable for both practicing physicians and researchers. Ishihara continued to refine the designs and improve the color accuracy of the images into the late 1950s, while he also served as the chair of the ophthalmology department and then dean of the medical school at Tokyo Imperial University. In addition to Tests for Colour Deficiency, he also published an atlas, textbook, lectures, and research studies on eye diseases. But he is remembered most for the iconic charts that seamlessly blend art and science.

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Penn Vet Working Dog Center
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Stones, Bones, and Wrecks
New Program Trains Dogs to Sniff Out Art Smugglers
Penn Vet Working Dog Center
Penn Vet Working Dog Center

Soon, the dogs you see sniffing out contraband at airports may not be searching for drugs or smuggled Spanish ham. They might be looking for stolen treasures.

K-9 Artifact Finders, a new collaboration between New Hampshire-based cultural heritage law firm Red Arch and the University of Pennsylvania, is training dogs to root out stolen antiquities looted from archaeological sites and museums. The dogs would be stopping them at borders before the items can be sold elsewhere on the black market.

The illegal antiquities trade nets more than $3 billion per year around the world, and trafficking hits countries dealing with ongoing conflict, like Syria and Iraq today, particularly hard. By one estimate, around half a million artifacts were stolen from museums and archaeological sites throughout Iraq between 2003 and 2005 alone. (Famously, the craft-supply chain Hobby Lobby was fined $3 million in 2017 for buying thousands of ancient artifacts looted from Iraq.) In Syria, the Islamic State has been known to loot and sell ancient artifacts including statues, jewelry, and art to fund its operations.

But the problem spans across the world. Between 2007 and 2016, U.S. Customs and Border Control discovered more than 7800 cultural artifacts in the U.S. looted from 30 different countries.

A yellow Lab sniffs a metal cage designed to train dogs on scent detection.
Penn Vet Working Dog Center

K-9 Artifact Finders is the brainchild of Rick St. Hilaire, the executive director of Red Arch. His non-profit firm researches cultural heritage property law and preservation policy, including studying archaeological site looting and antiquities trafficking. Back in 2015, St. Hilaire was reading an article about a working dog trained to sniff out electronics that was able to find USB drives, SD cards, and other data storage devices. He wondered, if dogs could be trained to identify the scents of inorganic materials that make up electronics, could they be trained to sniff out ancient pottery?

To find out, St. Hilaire tells Mental Floss, he contacted the Penn Vet Working Dog Center, a research and training center for detection dogs. In December 2017, Red Arch, the Working Dog Center, and the Penn Museum (which is providing the artifacts to train the dogs) launched K-9 Artifact Finders, and in late January 2018, the five dogs selected for the project began their training, starting with learning the distinct smell of ancient pottery.

“Our theory is, it is a porous material that’s going to have a lot more odor than, say, a metal,” says Cindy Otto, the executive director of the Penn Vet Working Dog Center and the project’s principal investigator.

As you might imagine, museum curators may not be keen on exposing fragile ancient materials to four Labrador retrievers and a German shepherd, and the Working Dog Center didn’t want to take any risks with the Penn Museum’s priceless artifacts. So instead of letting the dogs have free rein to sniff the materials themselves, the project is using cotton balls. The researchers seal the artifacts (broken shards of Syrian pottery) in airtight bags with a cotton ball for 72 hours, then ask the dogs to find the cotton balls in the lab. They’re being trained to disregard the smell of the cotton ball itself, the smell of the bag it was stored in, and ideally, the smell of modern-day pottery, eventually being able to zero in on the smell that distinguishes ancient pottery specifically.

A dog looks out over the metal "pinhweel" training mechanism.
Penn Vet Working Dog Center

“The dogs are responding well,” Otto tells Mental Floss, explaining that the training program is at the stage of "exposing them to the odor and having them recognize it.”

The dogs involved in the project were chosen for their calm-but-curious demeanors and sensitive noses (one also works as a drug-detection dog when she’s not training on pottery). They had to be motivated enough to want to hunt down the cotton balls, but not aggressive or easily distracted.

Right now, the dogs train three days a week, and will continue to work on their pottery-detection skills for the first stage of the project, which the researchers expect will last for the next nine months. Depending on how the first phase of the training goes, the researchers hope to be able to then take the dogs out into the field to see if they can find the odor of ancient pottery in real-life situations, like in suitcases, rather than in a laboratory setting. Eventually, they also hope to train the dogs on other types of objects, and perhaps even pinpoint the chemical signatures that make artifacts smell distinct.

Pottery-sniffing dogs won’t be showing up at airport customs or on shipping docks soon, but one day, they could be as common as drug-sniffing canines. If dogs can detect low blood sugar or find a tiny USB drive hidden in a house, surely they can figure out if you’re smuggling a sculpture made thousands of years ago in your suitcase.

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Medicine
New Cancer-Fighting Nanobots Can Track Down Tumors and Cut Off Their Blood Supply
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iStock

Scientists have developed a new way to cut off the blood flow to cancerous tumors, causing them to eventually shrivel up and die. As Business Insider reports, the new treatment uses a design inspired by origami to infiltrate crucial blood vessels while leaving the rest of the body unharmed.

A team of molecular chemists from Arizona State University and the Chinese Academy of Sciences describe their method in the journal Nature Biotechnology. First, they constructed robots that are 1000 times smaller than a human hair from strands of DNA. These tiny devices contain enzymes called thrombin that encourage blood clotting, and they're rolled up tightly enough to keep the substance contained.

Next, researchers injected the robots into the bloodstreams of mice and small pigs sick with different types of cancer. The DNA sought the tumor in the body while leaving healthy cells alone. The robot knew when it reached the tumor and responded by unfurling and releasing the thrombin into the blood vessel that fed it. A clot started to form, eventually blocking off the tumor's blood supply and causing the cancerous tissues to die.

The treatment has been tested on dozen of animals with breast, lung, skin, and ovarian cancers. In mice, the average life expectancy doubled, and in three of the skin cancer cases tumors regressed completely.

Researchers are optimistic about the therapy's effectiveness on cancers throughout the body. There's not much variation between the blood vessels that supply tumors, whether they're in an ovary in or a prostate. So if triggering a blood clot causes one type of tumor to waste away, the same method holds promise for other cancers.

But before the scientists think too far ahead, they'll need to test the treatments on human patients. Nanobots have been an appealing cancer-fighting option to researchers for years. If effective, the machines can target cancer at the microscopic level without causing harm to healthy cells. But if something goes wrong, the bots could end up attacking the wrong tissue and leave the patient worse off. Study co-author Hao Yan believes this latest method may be the one that gets it right. He said in a statement, "I think we are much closer to real, practical medical applications of the technology."

[h/t Business Insider]

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