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 IshiharaWellcome 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.

10 Reusable Gifts for Your Eco-Friendliest Friend

Disposable tea bags can't compete with this pla-tea-pus and his friends.
Disposable tea bags can't compete with this pla-tea-pus and his friends.
DecorChic/Amazon

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

By this point, your eco-friendly pal probably has a reusable water bottle that accompanies them everywhere and some sturdy grocery totes that keep their plastic-bag count below par. Here are 10 other sustainable gift ideas that’ll help them in their conservation efforts.

1. Reusable Produce Bags; $13

No more staticky plastic bags.Naturally Sensible/Amazon

The complimentary plastic produce bags in grocery stores aren’t great, but neither is having all your spherical fruits and vegetables roll pell-mell down the checkout conveyor belt. Enter the perfect alternative: mesh bags that are nylon, lightweight, and even machine-washable.

Buy it: Amazon

2. Animal Tea Infusers; $16

Nothing like afternoon tea with your tiny animal friends.DecorChic/Amazon

Saying goodbye to disposable tea bags calls for a quality tea diffuser, and there’s really no reason why it shouldn’t be shaped like an adorable animal. This “ParTEA Pack” includes a hippo, platypus, otter, cat, and owl, which can all hang over the edge of a glass or mug. (In other words, you won’t have to fish them out with your fingers or dirty a spoon when your loose leaf is done steeping.)

Buy it: Amazon

3. Rocketbook Smart Notebook; $25

Typing your notes on a tablet or laptop might save trees, but it doesn’t quite capture the feeling of writing on paper with a regular pen. The Rocketbook, on the other hand, does. After you’re finished filling a page with sketches, musings, or whatever else, you scan it into the Rocketbook app with your smartphone, wipe it clean with the microfiber cloth, and start again. This one also comes with a compatible pen, but any PILOT FriXion pens will do.

Buy it: Amazon

4. Food Huggers; $13

"I'm a hugger!"Food Huggers/Amazon

It’s hard to compete with the convenience of plastic wrap or tin foil when it comes to covering the exposed end of a piece of produce or an open tin can—and keeping those leftovers in food storage containers can take up valuable space in the fridge. This set of five silicone Food Huggers stretch to fit over a wide range of circular goods, from a lidless jar to half a lemon.

Buy it: Amazon

5. Swiffer Mop Pads; $15

For floors that'll shine like the top of the Chrysler Building.Turbo Microfiber/Amazon

Swiffers may be much less unwieldy than regular mops, but the disposable pads present a problem to anyone who likes to keep their trash output to a minimum. These machine-washable pads fasten to the bottom of any Swiffer WetJet, and the thick microfiber will trap dirt and dust instead of pushing it into corners. Each pad lasts for at least 100 uses, so you’d be saving your eco-friendly friend quite a bit of money, too.

Buy it: Amazon

6. SodaStream for Sparkling Water; $69

A fondness for fizzy over flat water doesn’t have to mean buying it bottled. Not only does the SodaStream let you make seltzer at home, but it’s also small enough that it won’t take up too much precious counter space. SodaStream also sells flavor drops to give your home-brewed beverage even more flair—this pack from Amazon ($25) includes mango, orange, raspberry, lemon, and lime.

Buy it: Amazon

7. Washable Lint Roller; $13

Roller dirty.iLifeTech/Amazon

There’s a good chance that anyone with a pet (or just an intense dislike for lint) has lint-rolled their way through countless sticky sheets. iLifeTech’s reusable roller boasts “the power of glue,” which doesn’t wear off even after you’ve washed it. Each one also comes with a 3-inch travel-sized version, so you can stay fuzz-free on the go.

Buy it: Amazon

8. Countertop Compost Bin; $23

Like a tiny Tin Man for your table.Epica/Amazon

Even if you keep a compost pile in your own backyard, it doesn’t make sense to dash outside every time you need to dump a food scrap. A countertop compost bin can come in handy, especially if it kills odors and blends in with your decor. This 1.3-gallon pail does both. It’s made of stainless steel—which matches just about everything—and contains an activated-charcoal filter that prevents rancid peels and juices from stinking up your kitchen.

Buy it: Amazon

9. Fabric-Softening Dryer Balls; $17

Also great for learning how to juggle without breaking anything.Smart Sheep

Nobody likes starchy, scratchy clothes, but some people might like blowing through bottles of fabric softener and boxes of dryer sheets even less. Smart Sheep is here to offer a solution: wool dryer balls. Not only do they last for more than 1000 loads, they also dry your laundry faster. And since they don’t contain any chemicals, fragrances, or synthetic materials, they’re a doubly great option for people with allergies and/or sensitive skin.

Buy it: Amazon

10. Rechargeable Batteries; $40

Say goodbye to loose batteries in your junk drawer.eneloop/Amazon

While plenty of devices are rechargeable themselves, others still require batteries to buzz, whir, and change the TV channel—so it’s good to have some rechargeable batteries on hand. In addition to AA batteries, AAA batteries, and a charger, this case from Panasonic comes with tiny canisters that function as C and D batteries when you slip the smaller batteries into them.

Buy it: Amazon

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Scientists Come Closer to Understanding COVID-19 'Cytokine Storms'

Science is closer to understanding what prompts severe COVID-19 illness.
Science is closer to understanding what prompts severe COVID-19 illness.
Photo by Artem Podrez from Pexels

Researchers are one step closer to understanding the mechanisms behind "cytokine storms," an immune system reaction that can cause severe COVID-19 symptoms in patients infected with the coronavirus. In a new paper published in the journal Cell, scientists from St. Jude Children's Research Hospital describe their identification of the specific cytokines, or small proteins, that are produced by the body in an effort to fight the virus but sometimes overreact and wind up causing damage, including inflammation, lung injury, and organ failure.

After examining the many different kinds of cytokines in the body, researchers determined that no single cytokine caused this inflammatory response. Instead, it appears to be a combination of two specific cytokines, dubbed tumor necrosis factor (TNF)-alpha and interferon (INF)-gamma, that work in collusion to cause inflammatory cell death.

By identifying these proteins as the culprit, researchers suggested that administering neutralizing antibodies and disrupting the protein pathways that promote cell death might present a new treatment method for COVID-19.

COVID-19 can prompt a "cytokine storm" that can cause severe symptoms.St. Jude Children's Research Hospital

"Understanding the pathways and mechanism driving this inflammation is critical to develop effective treatment strategies," co-author Thirumala-Devi Kanneganti, vice chair of St. Jude's department of immunology, said in a press release. "This research provides that understanding. We also identified the specific cytokines that activate inflammatory cell death pathways and have considerable potential for treatment of COVID-19 and other highly fatal diseases, including sepsis."

Thus far, this theory has only been tested in mice, which received neutralizing antibodies and were protected from severe COVID-19 symptoms. But in isolating the exact cytokines involved, it will likely be easier to locate an effective treatment, either from an existing drug or one developed specifically for the task. In time, researchers hope clinical trials of select drugs can be another tool in the fight against the virus.

[h/t PennLive]