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Do Carrots Improve Your Vision? 15 Misconceptions About Your Eyesight

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We can probably all recount at least a dozen weird and alarming things parents, teachers, and older siblings told us about our eyes when we were kids. For instance, we’d be permanently cross-eyed if we didn’t stop making those faces at our brother or we’d go blind from reading in the dark. But maybe, just maybe, we could find redemption by eating lots of carrots. Here are a few common myths and misconceptions.

MYTH #1: IF YOU CROSS YOUR EYES, THEY'LL STAY THAT WAY.

It’s a myth that your eyes will “freeze” if you cross them for too long. Crossed eyes, or strabismus, occurs when your eyes don’t look the same way at the same time. There are six muscles attached to each of our eyes that, guided by signals from the brain, control their movements. When your eyes don’t align, the brain gets two different images. Over time, this can cause more serious vision issues. That’s a real problem, but it’s not caused by making your eyes cross on purpose for short periods of time.

MYTH #2. EATING CARROTS WILL HELP YOU SEE IN THE DARK.

Well, carrots certainly aren’t bad for your eyesight. They contain plenty of beta-carotene, which your body converts into vitamin A, a crucial vitamin for vision. But carrots don’t do anything exceptional for your nighttime vision.

MYTH #3: THE BIGGER YOUR EYES, THE BETTER YOUR EYESIGHT.

When you’re born, your eyeballs are approximately 16 millimeters in diameter, reaching 24 millimeters as an adult. But your eyes getting larger does not necessarily mean that your vision is getting better. In fact, excessive growth in human eyes can cause myopia, or nearsightedness. If the eyeball is too long, the eye’s lens can’t focus the light in the right part of the retina to process images clearly.

MYTH #4: PUPIL DILATION OCCURS ONLY IN RESPONSE TO CHANGES IN LIGHT.

We all know that pupils contract in light and dilate in darker conditions. But did you know that pupils also respond to changes in our emotional and mental state? Sexual arousal, solving a complicated mental math problem, fear, and other cognitive and emotional events can provoke changes in pupil size, though the precise reasons why are not yet clearly understood.

MYTH #5: UV RAYS CAN ONLY DAMAGE EYES WHEN THE SUN IS SHINING.

Even on cloudy and foggy days, ultraviolet (UV) radiation can cause eye damage. The rays can be reflected off of water, sand, snow and shiny surfaces. So make sure to keep your 100 percent UV protection sunglasses handy whenever you are out and about. Years of exposure can increase your risk of developing cataracts, a clouding of the eye lens that can cause vision loss.

MYTH #6: WEARING GLASSES TOO MUCH CAN MAKE YOUR EYESIGHT WORSE.

This myth suggests that over-reliance on glasses for common vision problems like nearsightedness, farsightedness, and astigmatism will weaken or damage eyes. That’s not true, nor will your eyes be damaged by wearing glasses with a prescription that’s too strong—though it may give you a temporary strain or headache.

However, children should still be given the correct prescription. A 2002 study found that giving children glasses with a prescription that is too weak can increase their myopia, while giving the correct prescription “reduces the progression of myopia.”

MYTH #7: READING IN DIM LIGHT WILL DIMINISH YOUR EYESIGHT.

How many of you recall your parents telling you to “put some light on the subject” when you were curled up with a good book in dwindling daylight? Having more light can certainly help you see better, because it makes it easier for you to focus. But while reading in semi-darkness may put a temporary strain on your eyes, it’s not going to permanently damage your eyesight. Recent studies indicate not getting enough daylight in general, however, may have a detrimental effect on vision.

MYTH #8: IF YOUR PARENTS HAVE BAD EYESIGHT, YOU WILL, TOO.

You might, of course, because some eye problems are genetic. But there’s no guarantee that we will develop the same vision impairments as our parents. One study found that if both parents are myopic, there’s a 30 to 40 percent chance that the child is. If only one parent is myopic, the child has a 20 to 25 percent chance, and it's down to 10 percent for kids with non-myopic parents.

MYTH #9: TOO MUCH SCREEN TIME WILL DESTROY YOUR EYESIGHT.

Optometrists frequently debate this topic, but most agree that it’s not too damaging for most people. Having said that, more and more people are complaining of symptoms like dry, irritated eyes, headaches, eye strain and difficulty focusing after prolonged periods of screen time. The American Optometric Association (AOA) defines this group of symptoms collectively as Computer Vision Syndrome—or Digital Eye Strain—which can be further exacerbated by trying to focus on small screens such as tablets or phones. The AOA recommends following the 20-20-20 rule to remediate the effects of screen time: Every 20 minutes, take a 20-second break to look at something 20 feet away.

MYTH #10: THE RIGHT "VITAMIN COCKTAIL" CAN PREVENT VISION DECLINE.

Recent studies don’t support the notion that the right combination of vitamins can keep your eyesight from deteriorating, according to Harvard researchers. A National Institutes of Health study showed that antioxidant vitamins may help slow the progression of macular degeneration, one of the most common causes of vision loss as we age. But for people not already suffering from the disease, preventative use of such vitamins didn’t appear to make a significant difference. Perhaps an effective vitamin cocktail will be discovered one day, but so far, there’s no proof that it works.

MYTH #11: DYSLEXIA IS LINKED TO VISION PROBLEMS.

A recent study from Bristol and Newcastle Universities in the UK found that children with dyslexia were no more likely than others to suffer from common vision problems like myopia, far-sightedness, squinting or focusing problems.

MYTH #12: IF YOU DON'T TREAT LAZY EYE WHEN YOU'RE A SMALL CHILD, YOU'LL HAVE IT FOREVER.

Lazy eye, or amblyopia, occurs when nerve pathways between the brain and the eye aren’t properly stimulated, causing the brain to favor one eye over the other. The weaker eye tends to wander, and eventually the brain might ignore signals received from that eye. While doctors say that the sooner it’s treated the better, there are an increasing number of remedies (including Tetris) that can help adults as well.

MYTH #13: BLIND PEOPLE SEE ONLY DARKNESS.

According to the American Foundation for the Blind, only 18 percent of people who have visual impairments are totally blind. Most are able to differentiate between light and dark.

MYTH #14: HUMAN VISION IS THE SAME IN SPACE AS IT IS ON EARTH.

Actually, NASA scientists have found that space can impair our vision, though they still aren’t sure why. A study of seven astronauts who spent more than six months on the International Space Station noted that all experienced blurry vision during and for months after their space mission. The researchers hypothesized that the shift of fluids toward the head that can occur in microgravity might have something to do with it. Now, NASA is following up with a study that will track the vision of crew members during and after long space missions to try and determine exactly why these vision changes occur in space.

MYTH #15: PEOPLE WHO ARE COLORBLIND CAN'T SEE COLOR.

The human eye and brain work together to interpret color from light, and each of us perceives color slightly differently. We all have photopigments—color-detecting molecules—in cone-shaped cells inside our retinas. But people who suffer from hereditary color blindness have defects in the genes that direct production of photopigments. It’s quite rare for someone not to see color at all, however. It's more common for color blind individuals to have difficulty differentiating between certain colors, like red and green, or blue and yellow. And while color blindness is far more common in males than females, it does affect a small percentage of women.

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Today's Wine Glasses Are Almost Seven Times Larger Than They Were in 1700
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Holiday party season (a.k.a. hangover season) is in full swing. While you likely have no one to blame but yourself for drinking that second (or third) pour at the office soiree, your glassware isn't doing you any favors—especially if you live in the UK. Vino vessels in England are nearly seven times larger today than they were in 1700, according to a new study spotted by Live Science. These findings were recently published in the English medical journal The BMJ.

Researchers at the University of Cambridge measured more than 400 wineglasses from the past three centuries to gauge whether glass size affects how much we drink. They dug deep into the history of parties past, perusing both the collections of the Ashmolean Museum of Art and Archaeology at the University of Oxford and the Royal Household's assemblage of glassware (a new set is commissioned for each monarch). They also scoured a vintage catalog, a modern department store, and eBay for examples.

After measuring these cups, researchers concluded that the average wineglass in 1700 held just 2.2 fluid ounces. For comparison's sake, that's the size of a double shot at a bar. Glasses today hold an average of 15.2 fluid ounces, even though a standard single serving size of wine is just 5 ounces.

BMJ infographic detailing increases in wine glass size from 1700 to 2017
BMJ Publishing group Ltd.

Advances in technology and manufacturing are partly to blame for this increase, as is the wine industry. Marketing campaigns promoted the beverage as it increasingly became more affordable and available for purchase, which in turn prompted aficionados to opt for larger pours. Perhaps not surprisingly, this bigger-is-better mindset was also compounded by American drinking habits: Extra-large wineglasses became popular in the U.S. in the 1990s, prompting overseas manufacturers to follow suit.

Wine consumption in both England and America has risen dramatically since the 1960s [PDF]. Cambridge researchers noted that their study doesn't necessarily prove that the rise of super-sized glassware has led to this increase. But their findings do fit a larger trend: previous studies have found that larger plate size can increase food consumption. This might be because they skew our sense of perception, making us think we're consuming less than we actually are. And in the case of wine, in particular, oversized glasses could also heighten our sensory enjoyment, as they might release more of the drink's aroma.

“We cannot infer that the increase in glass size and the rise in wine consumption in England are causally linked,” the study's authors wrote. “Nor can we infer that reducing glass size would cut drinking. Our observation of increasing size does, however, draw attention to wine glass size as an area to investigate further in the context of population health.”

[h/t Live Science]

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Researchers Pore Over the Physics Behind the Layered Latte
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The layered latte isn't the most widely known espresso drink on coffee-shop menus, but it is a scientific curiosity. Instead of a traditional latte, where steamed milk is poured into a shot (or several) of espresso, the layered latte is made by pouring the espresso into a glass of hot milk. The result is an Instagram-friendly drink that features a gradient of milky coffee colors from pure white on the bottom to dark brown on the top. The effect is odd enough that Princeton University researchers decided to explore the fluid dynamics that make it happen, as The New York Times reports.

In a new study in Nature Communications, Princeton engineering professor Howard Stone and his team explore just what creates the distinct horizontal layers pattern of layered latte. To find out, they injected warm, dyed water into a tank filled with warm salt water, mimicking the process of pouring low-density espresso into higher-density steamed milk.

Four different images of a latte forming layers over time
Xue et al., Nature Communications (2017)

According to the study, the layered look of the latte forms over the course of minutes, and can last for "tens of minutes, or even several hours" if the drink isn't stirred. When the espresso-like dyed water was injected into the salt brine, the downward jet of the dyed water floated up to the top of the tank, because the buoyant force of the low-density liquid encountering the higher-density brine forced it upward. The layers become more visible when the hot drink cools down.

The New York Times explains it succinctly:

When the liquids try to mix, layered patterns form as gradients in temperature cause a portion of the liquid to heat up, become lighter and rise, while another, denser portion sinks. This gives rise to convection cells that trap mixtures of similar densities within layers.

This structure can withstand gentle movement, such as a light stirring or sipping, and can stay stable for as long as a day or more. The layers don't disappear until the liquids cool down to room temperature.

But before you go trying to experiment with layering your own lattes, know that it can be trickier than the study—which refers to the process as "haphazardly pouring espresso into a glass of warm milk"—makes it sound. You may need to experiment several times with the speed and height of your pour and the ratio of espresso to milk before you get the look just right.

[h/t The New York Times]

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