CLOSE
iStock
iStock

Why Do Optometrists Blow Puffs of Air Into Your Eye?

iStock
iStock

I’m basically blind without my contacts, so every year I dutifully schlep to the optometrist to get my eyes tested and outfitted for a new prescription. And every year, I dread it—not just because of the pressure to read the tiniest lines without squinting (just me?), but because of the part of the exam where the doctor has me sit in front of a machine and blasts two puffs of air into each eye. Yesterday, I sat through the torturous puffs of air again, and I asked my optometrist: Is this necessary? Can I skip it next time?

Unfortunately for me, this part of the eye exam helps the doctor determine the fluid pressure inside my eyeball, and is therefore totally necessary. High pressure in the eye can cause glaucoma, or vision loss due to damage of the optic nerve. So the doctor asks me to put my chin on the chin rest, stare at a green light, and then uses a machine called a non-contact tonometer to administer two gentle (but totally startling) puffs of air onto the surface of my eye. The machine measures the air that bounces back and then calculates my intraocular pressure. No one likes this part of the test; it was even the subject of an episode of Friends:

There are other ways to test for glaucoma, but many optometrists opt for the air puff test because it’s quick and painless for the patient. So I guess next year, I'll just have to open my eyes up wide and bear it.

nextArticle.image_alt|e
iStock
arrow
Big Questions
Why Does Turkey Make You Tired?
iStock
iStock

Why do people have such a hard time staying awake after Thanksgiving dinner? Most people blame tryptophan, but that's not really the main culprit. And what is tryptophan, anyway?

Tryptophan is an amino acid that the body uses in the processes of making vitamin B3 and serotonin, a neurotransmitter that helps regulate sleep. It can't be produced by our bodies, so we need to get it through our diet. From which foods, exactly? Turkey, of course, but also other meats, chocolate, bananas, mangoes, dairy products, eggs, chickpeas, peanuts, and a slew of other foods. Some of these foods, like cheddar cheese, have more tryptophan per gram than turkey. Tryptophan doesn't have much of an impact unless it's taken on an empty stomach and in an amount larger than what we're getting from our drumstick. So why does turkey get the rap as a one-way ticket to a nap?

The urge to snooze is more the fault of the average Thanksgiving meal and all the food and booze that go with it. Here are a few things that play into the nap factor:

Fats: That turkey skin is delicious, but fats take a lot of energy to digest, so the body redirects blood to the digestive system. Reduced blood flow in the rest of the body means reduced energy.

Alcohol: What Homer Simpson called the cause of—and solution to—all of life's problems is also a central nervous system depressant.

Overeating: Same deal as fats. It takes a lot of energy to digest a big feast (the average Thanksgiving meal contains 3000 calories and 229 grams of fat), so blood is sent to the digestive process system, leaving the brain a little tired.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

nextArticle.image_alt|e
Getty Images
arrow
Big Questions
How Are Balloons Chosen for the Macy's Thanksgiving Day Parade?
Getty Images
Getty Images

The balloons for this year's Macy’s Thanksgiving Day Parade range from the classics like Charlie Brown to more modern characters who have debuted in the past few years, including The Elf On The Shelf. New to the parade this year are Olaf from Disney's Frozen and Chase from Paw Patrol. But how does the retail giant choose which characters will appear in the lineup?

Balloon characters are chosen in different ways. For example, in 2011, Macy’s requested B. Boy after parade organizers saw the Tim Burton retrospective at the Museum of Modern Art. (The company had been adding a series of art balloons to the parade lineup since 2005, which it called the Blue Sky Gallery.) When it comes to commercial balloons, though, it appears to be all about the Benjamins.

First-time balloons cost at least $190,000—this covers admission into the parade and the cost of balloon construction. After the initial year, companies can expect to pay Macy’s about $90,000 to get a character into the parade lineup. If you consider that the balloons are out for only an hour or so, that’s about $1500 a minute.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios