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in all states or situations. This

1:09

is But Why, a podcast for curious

1:11

kids from Vermont Public. I'm Jane Lindholm.

1:13

On this show, we take questions from

1:15

curious kids all over the world and

1:17

find interesting people to answer them. Many,

1:20

many years ago now, we did a couple of

1:22

episodes about our bodies and how they work. We

1:25

had so many questions just about eyes

1:27

that we actually didn't include eyes at

1:30

all in those episodes, and

1:32

we promised at the time we'd make another

1:34

one just about eyes. Well,

1:36

time got away from us, but here we are

1:38

now with not one, but two

1:41

episodes about eyes, eyeballs, and

1:43

eyeglasses. We decided

1:45

to take your eyeball and cite questions with

1:47

us to a doctor's office at the University

1:49

of Vermont Medical Center, where I thought we

1:51

could also find out what happens when you

1:53

get an eye exam. I'm Sujata

1:55

Singh. I'm the pediatric ophthalmologist

1:57

at University of Vermont. do

2:01

eye exams just for kids

2:03

and also for older adults who have

2:05

maybe trouble communicating. I also help develop

2:07

vision for little kids because they're still

2:10

learning how to see and

2:12

that requires a whole different

2:14

specialized skills compared to

2:16

what the adult ophthalmologists have to be skilled

2:18

in doing. What does the

2:20

word ophthalmology mean? That's such a big and

2:22

cool word but you said you're an eye

2:25

doctor. Why do we have to call you

2:27

an ophthalmologist? There

2:29

are a few words that describe different kinds of

2:31

eye doctors. An ophthalmologist

2:33

which has a few too

2:36

many ages I think for most people, they

2:39

are eye doctors and surgeons

2:41

so we went to medical

2:43

school, did four years of

2:45

training after medical school and

2:49

learned how to take care of patients, take

2:51

care of the surgeries and I

2:54

did an extra year to learn how

2:56

to take care of kids and so

2:58

that's what an ophthalmologist does. Sometimes going

3:00

to any doctor or any medical office

3:02

can be really nerve-wracking and can make

3:04

people anxious or sometimes it's fun because

3:06

you get to learn things about your

3:09

body and sometimes it's both. Will

3:11

you walk me through an eye exam

3:13

while I ask you questions that kids

3:15

have sent us about eyes? Yes absolutely.

3:17

Okay what do I have to do

3:19

first? We have you sit in the big chair.

3:21

If you're really little we'll have you sit with whoever

3:23

brought you in on their lap because we want you

3:25

to be comfortable and also tall enough for me to

3:27

take a look at your eyes. Alright I'm gonna sit

3:30

in the chair Melody I think I'm big enough that

3:32

I don't need to sit on your lap so I'm

3:34

gonna sit by myself. This

3:37

chair kind of reminds me of a

3:40

little bit like the chair you'd sit at at

3:42

a dentist's office. It's pretty similar I would say

3:44

but the best part about it is that it

3:46

does this. Oh I'm

3:48

going back, oh I'm leaning back it's time for a nap.

3:51

It's a great spot for a nap and then we can

3:53

bring you back up with some buttons and the kids are

3:55

also usually clever and they find it before I can show

3:57

them. Okay so you're

3:59

seeing sitting in front of me, what

4:02

are you going to do to my eyes? Do I need to take

4:04

off my glasses? So yes, if you're

4:06

wearing glasses, the first thing we'll do is look

4:08

at you with your glasses on. One

4:10

of the biggest things that help us decide

4:13

how we can help you is getting

4:16

your visual acuities. And so that's a fancy

4:18

word for just knowing how you see. And

4:20

we do both eyes if you

4:22

have two eyes, and we do one eye at

4:24

a time usually. And so

4:26

we'll use this guy, which is called

4:29

an occluder. It looks like a big spoon

4:31

with a red see-through thing on the end.

4:33

It's like a soup spoon. We've had kids

4:35

try to eat the soup spoon. But

4:38

we'll hold that right up to

4:40

one of your eyes and have

4:42

you look all the way down

4:44

this very long room at

4:47

the TV that has some

4:49

either letters, or we have

4:51

all sorts of different symbols,

4:53

also pictures. And we have

4:55

the HOTV letters and then the

4:57

alphabet also. So if I don't know

4:59

my alphabet or don't use these types

5:01

of letters, I can still do pictures.

5:03

Yeah, absolutely. And if you're really, really

5:06

shy or if you're still working on

5:08

learning your letters, which is totally understandable,

5:10

we also have these matching cards. So

5:13

you might kind of recognize

5:15

the HOTV, but it can be,

5:18

like I said, you can be either shy or not sure have

5:21

a lot of anxiety about being completely right.

5:24

But you are really good at matching, which

5:26

most kids are. So we're talking

5:28

about eyes and talking about eyesight.

5:31

And so I think all of

5:33

us probably already know that your

5:35

eyes are the organs that help

5:37

you see. What

5:39

are eyes made out of? Hi,

5:42

my name is Rose, and I

5:44

live in Kitchener, Ontario, Canada. I

5:47

am 6 and 1 by 2 years old,

5:49

and my question is, what are eyes made

5:52

of? That is a really

5:54

great question, actually. I have to think about how

5:56

to answer that. So your eyes

5:58

are made out of what? what's called tissue,

6:00

different parts of the body is made out

6:02

of different kinds of tissue, right? Like

6:05

your bones aren't the same thing as

6:07

your skin, but they're both very important

6:09

and they are built

6:11

to give you the best function.

6:16

And so they're made of,

6:18

I don't know how exactly precise

6:20

how much to go into it,

6:22

but there are very, it is

6:24

a complex device. So there are

6:26

a lot of different layers to

6:28

it and they're highly, highly

6:30

specialized and very delicate. Eyes

6:32

are complicated. It's no wonder

6:34

Dr. Singh was trying to think hard about how to

6:37

explain it all. We'll get deeper

6:39

into some of the structures of the

6:41

eye in a minute, but just to

6:43

give you a sense of what your

6:45

eye is made of, there are blood

6:47

vessels, a mucous membrane, nerve tissues, light

6:49

receptors, muscles, and a see-through

6:51

jelly-like substance that fills a lot of

6:53

the inside of your eyeball called the

6:56

vitreous humor. My name is Gracie and

6:58

I live in Bend, Oregon and I'm

7:01

four years old and my

7:04

question is how do eyes work?

7:07

Hi, my name is Iris.

7:09

I'm seven years old. I

7:11

live in the UK and

7:14

my question is how do eyes

7:16

work? Hello, my name

7:18

is Ethan. I'm five years old.

7:20

I live in San

7:22

Jose, California and

7:24

my question is how does

7:27

eyeball feel? My

7:29

name is Louie. I'm

7:32

six years old. I'm

7:35

in Boston, Illinois, in the

7:37

Netherlands. My question is

7:40

how do your eyes work? I

7:43

am Liam. I am four years old. I

7:46

would like to know how eyeballs

7:49

work. The eyes,

7:52

their job is to deliver images

7:54

from the world into

7:56

the brain and so they're literally what

7:59

we call optical. devices. Glasses are optical

8:01

devices. They're just there to deliver images. The

8:03

front part of the eye is called the

8:05

cornea. That's the clear cap of tissue that

8:07

covers the colored part of the eye. The

8:09

colored part of the eye, whether it's green

8:11

or brown or blue or all sorts of

8:13

different colors, is called the

8:15

iris. It's like a ring of tissue with a

8:18

hole in the center. The black part is actually

8:20

the hole in the center, and that's

8:22

called the pupil and it contains sizes. That's why we give

8:24

you drops to make it as big as possible. Right

8:27

behind that is called a lens. That's

8:29

a disc-shaped structure. That can actually change

8:31

size and give you different focuses.

8:34

You can see clearly in the distance or see

8:36

clearly up close, but you can't see clearly at

8:38

both spots at the same time. That's

8:40

because your lens can change shape. Then

8:43

the inside is filled with a jelly, which is the funnest

8:45

part of course. The

8:48

back layer inside the eye is

8:50

the retina, which is very complex.

8:53

That's where you have your color vision. That's where you

8:55

have all the lights that

8:58

fill up the world, gets sharpened and

9:00

focused into an actual image that's upside

9:02

down and reversed when it

9:05

lands, similar to a camera. People

9:08

describe it as the film of the eye.

9:10

Then that gets

9:13

all transmitted to your optic nerve, which is

9:15

a cord that connects to

9:17

the brain. The brain is actually where we see. That's

9:21

why I say that the eyes are optical

9:23

devices, whereas the brain is the actual seeing

9:26

part of the body. If

9:30

I could pop my eye out right now, which I

9:32

won't try to do, if I tried to squeeze it,

9:37

would it feel like a marble or would it squeeze

9:39

like a tomato? A

9:41

lot of the time we call it the feeling of

9:43

a grape. It's

9:46

a little bit tense, but not tense.

9:48

It is squeezable and palpable. Yes, thank

9:50

you so much for not attempting

9:52

that. It's highly

9:54

not advisable. We're very big on eye

9:57

protection and especially piece of the mollities.

9:59

Thank you. Thank you. Hello, my name is

10:02

Gideon. I'm nine years old. I live in

10:04

Linden, Washington, and my question is, what

10:06

is the cornea of your eyeball

10:08

made of? It's

10:11

a thing called collagen. And

10:13

it's very, the way that it's actually layered

10:15

is it's shaped so that

10:17

it's, and stacked so that it's

10:21

transparent, which is the one of the

10:23

most interesting things about it. In

10:26

addition to how it curves is

10:29

how much of a power you

10:31

have in the eye. It's called a refractive power,

10:33

and basically that's kind of your

10:35

glasses prescription that's built into the eye. So

10:37

it's the shape of your eye, the shape

10:39

of the cornea especially, that gives you that.

10:41

The other thing that it does is keep

10:44

your eye comfortable. So it's supposed to be

10:46

smooth and well hydrated, like wet, to

10:49

get the best images

10:52

to the back of your eye and also to feel comfortable.

10:55

Hi, my name's Lane. I'm nine

10:57

years old. I'm from Vancouver,

11:00

BC, Canada. And my

11:02

question is, are your eyeballs really in

11:04

the shape of balls? It's

11:07

actually not. That's a really great question actually,

11:09

because it has different curvatures. So

11:11

as you go into the cornea, it's

11:14

a different kind of arc to it compared

11:16

to the rest of the eyeball, the white

11:18

part of the eye. So it's not quite

11:20

all a ball, but with eyeballs, it's still

11:22

a really good word for it. Hi,

11:26

my name is Saul. I'm

11:29

four years old. I'm

11:31

from Brooklyn. And

11:33

my question is, why

11:35

do we have to blink? My

11:39

name is Owen, and

11:41

I'm six years old. And

11:45

I live in Toronto, Ontario.

11:49

And my question is,

11:51

why do people

11:54

blink? Hi, my

11:56

name is Jason. I Live in Toronto.

12:01

And for any. Anime.

12:03

Find yourself five and a

12:06

half years old and. Are.

12:09

My close to a. Why?

12:13

Do your eyes blaze Hi

12:15

My name is been and

12:17

five years old. I

12:20

live in London, Ontario. My

12:22

question is how and why

12:25

doing so fast hi my

12:27

name is and then yes

12:29

I am a two years

12:32

on. I live in Cupertino,

12:34

California and my question is

12:36

why do we think hi?

12:38

I'm Chelsea I'm eight years

12:41

on and I'm fans have

12:43

her. My question is why

12:45

do we blame me with

12:47

cool. One.

12:51

Five, you know, And. Oh

12:54

my question is why do

12:56

a plane that I. Phoenix's.

12:59

Five and lives in Seattle. He

13:01

also wants to know our people

13:03

blink we burnt require a bird

13:06

images and then offered to hydrate.

13:08

I'd make it as not dry

13:10

as possible and make it feel

13:12

smooth and those in the main

13:14

reasons and also to point out

13:16

anything that might have any deaths

13:18

or anything from his last has

13:20

fallen there for their favorite and

13:22

to do with them nutrients. Office

13:25

blinking is also little bit like

13:27

breathing right in that we don't.

13:29

We have to do it. but we don't

13:31

have to think about it. It happens automatically.

13:33

Yes, exactly. Cat, We don't have to think.

13:35

About correct. A lot of kids

13:38

wanna know why we have two years

13:40

hi my name is Lucy and cities

13:42

all as a movie house engine. And.

13:45

Here's. The a warrior

13:48

singing Enemies Of Them. My

13:50

name is million seven years old. I'm

13:52

from the British Columbia Canada and my

13:54

question is why is is wider come

13:57

out of your eyes. when you cry

14:00

My name is Alex. I'm five

14:02

years old. I

14:05

live in whatever New York. My

14:09

question is, where do your tears

14:11

come from? Hi,

14:13

my name is Eleanor. I'm five

14:15

and a half years old. I'm

14:20

from Chicago, Illinois. My

14:23

question is, where do

14:26

tears come from? Hello,

14:29

my name is Imogen. I'm from

14:31

Australia. And

14:33

my question is, how are

14:36

teardrops made? Hello,

14:39

my name is Ella. I live in

14:41

Montreal, Canada. And

14:43

I'm from Japan. And

14:46

I'm four and a half years old. And

14:49

I want to know how your body makes tears. Hi,

14:53

my name is Oliver. I'm six years

14:55

old. I live in Miami,

14:57

Florida, and I want to know

15:00

how your eyes create tears. We

15:03

also got this same question from Lillian. How

15:05

do eyes make water to cry? So

15:08

the point of having tears is to

15:10

keep that cornea happy and healthy and as smooth

15:12

as possible. When it's

15:14

like that, it allows the light rays that

15:16

are bouncing around in the world to go

15:19

into your eyeball as smoothly as possible, as

15:21

sharply as possible. So that's one

15:23

big thing. And it actually, you have

15:25

to know some physical optics, but the

15:27

way the light rays go in, and

15:29

then it bends through the

15:31

cornea and actually the tears to

15:34

get sharpened inside your

15:36

eye. And you can

15:38

see how light bends through different medium, like when you

15:40

if you've ever put like a straw in a glass,

15:43

sorry, a glass of water, it doesn't stay straight through

15:45

the glass of water, right? It

15:48

bends. Or it looks like it's bending. Right,

15:51

exactly. And that's because the light rays are traveling

15:53

at different speeds because it got bent as it's

15:55

trying to pass through the water medium. And

15:57

the same thing happens in your eyeballs, and that's why the eyes

15:59

are so soft. an optical device because it changes the shape of

16:02

the light rays that are going through it. And

16:04

so that's a big part

16:06

of what tears help with. And it also just

16:08

helps kind of get

16:10

nutrients and immune defenses and all

16:12

sorts of things like that. It helps

16:15

me blink my eyes and

16:17

move my eyelids up and down smoothly. And

16:19

also when I get a piece of dust

16:21

in my eye, sometimes I make more tears.

16:23

So it can also kind of help get things that

16:26

aren't supposed to be in your eye out of

16:28

your eye too, right? You can produce more tears

16:30

to get bad stuff out of your eyes.

16:33

Yeah, exactly. The eyes, the corneas actually have

16:35

almost the densest amount

16:38

of nerves in the whole body.

16:41

It's a very tiny spot of tissue,

16:43

but it has a lot of nerves.

16:45

So that means it's really sensitive to

16:47

foreign objects. And then when it feels

16:49

that, all this tearing

16:51

happens. We call it reflexive tearing because

16:54

you don't try to do it. You just do

16:56

it automatically and then the tears wash it out. So,

16:58

yes, piers are our friend. My

17:00

name is Kylan. I'm eight years old. I am from

17:03

Kigali, Rwanda. My question is, why are tears salty? Thank you. My

17:05

name is Abby and I'm four years old. I live in Chicago, Illinois.

17:07

And my question

17:10

is, why do

17:12

tears taste salty? Your

17:27

tears taste salty because they are salty.

17:30

You have salt in your blood,

17:32

sweat, snot, and yes,

17:34

tears. You need some salt

17:36

to survive and it's all throughout your

17:38

body. Your tears are made up

17:41

of water, electrolytes, that's

17:43

what tastes salty, proteins,

17:45

oils, and sometimes hormones.

17:48

And there are different kinds of tears. Basal

17:51

tears are the kind that are constantly flowing

17:53

across your eye to keep it lubricated, what

17:55

Dr. Singh was talking about. Reflex

17:57

tears are made when you've got that speck of... dust

18:00

or an eyelash in your eye that you need to get out. And

18:03

emotional tears are the kind your body makes

18:05

when you're sad or injured or sometimes when

18:07

you're really happy. Tears

18:10

start toward the top of your eye

18:12

and drain into ducts that go into

18:14

your nose. That's why you might

18:16

get a stuffy nose when you've been crying. Let's

18:19

get back to the eye exam. Here's what

18:21

comes next. So if you're a new patient,

18:23

then next, I wanna make sure that your

18:25

pupils, that hole in the center of your

18:27

eye, we wanna make sure that that's normal.

18:30

We check that by using this light. I'll

18:33

take off my glasses. And

18:35

that we make sure that your pupils are as big as

18:37

possible. The way that they get as

18:39

big as possible is when the lights are down and

18:42

you're looking way down to the other end of the

18:44

room. So then your eyes are really big and then

18:46

I turn on my light and I get really close

18:49

and we shine the light on one side and

18:51

I see how well it reacts, meaning how well

18:53

it gets smaller and then the other side. And

18:55

then we keep doing that to make sure that

18:58

it's normal How

19:00

do I look? You look great. Very

19:02

nice brisk reaction. Your pupils

19:04

are round. Okay, so you shine some lights

19:06

in my eyes. Now what do we do?

19:08

So now we make sure that your visual

19:11

fields, meaning your peripheral field is normal. And

19:13

peripheral means on the outside. So you're checking

19:15

to make sure that not

19:17

only can I see what's straight ahead of me,

19:19

but I can also kind of see what's out

19:21

of the corners of my eyes without having to

19:23

move my eyes and move my head to the

19:26

center. Yep, exactly. And so we wanna make sure

19:28

you can see as wide out as possible. And

19:30

so usually with adults, you can have them follow

19:32

directions. So you can have them cover up one

19:35

eye and kind of put your fingers kind

19:37

of out in that peripheral field and see whether they

19:39

can see it while they're still looking at your nose.

19:42

It's a funny exam to look at,

19:45

but with kids, they sometimes

19:47

can't follow those directions but they wanna do a

19:49

really good job. So we

19:51

actually have some help, which is these

19:53

are my medical devices. So

19:56

I have some. little

20:01

toys. Finger puppets usually work pretty

20:03

well. They're the right size and they're bright and

20:05

I just have them wait and

20:08

give them have them give me a nonverbal

20:10

cue. So usually they, I don't

20:12

know about you though, so you

20:14

want me to tell you that I am seeing

20:16

this other finger puppet that's not at your nose

20:19

moving. Exactly and so kids, little kids will just

20:21

automatically look for the motion and

20:23

and tell me that they can see it. So

20:25

the one disadvantage of this is that they, I

20:27

can't test one eye at a time but I

20:29

can get a kind of sense of what their

20:31

peripheral visual fields are doing. Coming

20:33

up, why is it that we have two

20:35

eyes but only see one thing at a

20:37

time? Why can't our eyes

20:40

move independently of one another? This

20:44

is But Why, a podcast for curious kids.

20:46

We're learning all about eyes with Dr.

20:48

Sujata Singh. She's a pediatric ophthalmologist

20:51

at the University of Vermont Medical

20:53

Center. My name is

20:55

Ashton. I live in Boulburner tone

20:57

Florida. I'm six years old.

20:59

My question is why

21:02

do eyes look one way but

21:04

not two? Hi my

21:06

name is Eleanor. I'm from Buffalo, New

21:08

York. My question is why do you

21:10

have two eyes but see one picture?

21:12

My name is Rosie and I am

21:14

eight years old and I live in

21:17

Morristown, New Jersey and my question is

21:19

if you only have two eyes why

21:22

do you see one picture? We

21:24

have two eyes but

21:26

unlike some animals our

21:29

eyes don't move independently of one

21:31

another usually so we're usually using

21:33

two eyes to see the same

21:35

thing. So why do we need

21:38

two eyes if they're gonna move in the

21:40

same direction at the same time and see

21:42

the same thing? You do have two eyes

21:44

and if you look at something close one

21:46

eye and then switch and close the other

21:48

eye you'll notice that the eye

21:50

kind of the object actually

21:52

changes so you can't see the

21:54

same image from both

21:56

eyes. It's impossible because

21:58

they are set different. in a different spot

22:00

in space, and you're not a cyclops,

22:03

right? Both eyes aren't sitting in the same spot, so

22:05

they can have the same entrance. They're coming at whatever

22:07

you're looking at from different

22:10

angles. You can kind of test

22:12

that if you put your finger in front of

22:14

your eyes and in front of the thing that

22:16

you're trying to look at, and then close and

22:18

open your different eyes and watch your finger move

22:20

in front of you. Yeah, and the finger jumps

22:22

around, because that's the angle that your eye is

22:24

looking at. And so what

22:27

that tells you is that each eye is

22:29

actually bringing a different image to the brain.

22:32

And so that's what I was talking about

22:34

earlier, where those images, when

22:36

you push them together, then

22:39

you get 3D vision, basically.

22:41

So if you walk around, I

22:43

mean, in a safe environment, if you walk

22:45

around with one eye closed, you'll notice that you start

22:48

to have trouble doing a few things. If you try

22:50

to thread a needle, playing with blocks and stuff, you'll

22:52

notice all of a sudden, you can't do it as

22:54

easily or confidently as you could with two eyes. And

22:57

that's what the depth perception is

22:59

giving you. So that's your highest level

23:01

of vision. We call it binocular vision,

23:03

meaning using two eyes. And

23:06

you don't need it to

23:09

live life, right? Like we have lots of

23:11

doctors, teachers, and

23:14

artists out there who can see

23:17

really well out of one eye, not so well

23:19

out of the other eye, but that's why we

23:21

get two eyes. And it's nice to have a

23:23

backup. One of the things Dr. Singh can test

23:25

for is to make sure your eyes are aligned,

23:27

meaning they move in the same direction at the

23:29

same time. Sometimes, and this is

23:31

more common in kids, your

23:33

eye or eyes might turn inward or

23:36

outward. This condition

23:38

is called strabismus. An

23:40

ophthalmologist like Dr. Singh can work

23:42

with you to correct strabismus with

23:44

various treatments that include special glasses,

23:47

medicine, and eye exercises. So

23:49

the next thing is actually, since we were kind

23:52

of talking about it already, let's talk about depth

23:55

perception. So it's called, the fancy

23:57

word is stereopsis. So stereo. like

24:00

3D kind of thing and opsus

24:02

meaning vision. And

24:05

so I test your stereopsis

24:07

with 3D images. I'm

24:10

holding a little kind of booklet with one

24:13

has some shapes and numbers and

24:16

animals and then one has a fly

24:18

on it. It has a very fun fly.

24:21

And you can only see it with what I call

24:23

the magic glasses. They look kind of

24:25

like sunglasses, but really what they are is they have

24:27

a filter on one side, a filter on the other

24:29

side. I have you put those

24:31

on and then take a look. Whoa, they're 3D. That

24:34

fly looks like its wings are coming out at me.

24:37

Yeah, and so even a one-year-old

24:39

might put on the glasses and

24:41

actually automatically go after it. They might not

24:43

say those words. The fly is

24:45

coming out at me. I don't want it to jump off

24:47

the date, but they'll automatically try to

24:49

pick it up because that's what it looks like

24:51

to them because they have 3D vision. And

24:54

so basically this picture of a fly is actually two

24:56

different pictures that are just slightly off. And

24:59

then your glasses have a filter in one eye

25:01

and a filter in the other that are opposite

25:03

to each other. So the

25:05

pictures of the fly actually

25:08

go into each eye differently and

25:10

then your brain has to push them together and it pulls

25:12

out this 3D image. And so

25:14

that's a very like growth, meaning

25:17

very, not just growth because

25:19

it's a fly, but also growth because

25:21

it's very large amount. So you

25:23

can kind of tell it's popping out even when you're not

25:25

wearing the glasses. But then

25:27

we get into very finer and finer

25:29

levels of depth perception. Hi,

25:32

I'm curious why our pupils get smaller.

25:34

That black part of our eye in

25:36

the center, sometimes it's a really big

25:38

black circle and sometimes if it's really

25:40

bright outside it can be a really small

25:42

black circle. Yeah, no, that's

25:44

a really good description of it. It's

25:46

a really important part of our, our,

25:49

our viability to see is how much

25:51

light goes into our eyeball. So if

25:53

you, you can imagine if you have

25:55

too much light going into your eyeball you can't make

25:57

out the objects that you want to look at. with

26:00

high definition and high level of details.

26:02

So your pupils are what control the

26:04

amount of light that goes in. So

26:06

it's the nerves that

26:08

come from your eyeball into

26:10

your brain and then

26:13

from your brain into your eyeball, back into your

26:15

eyeball, is the pupillary reflex. And

26:17

that's what controls what size it is, and

26:19

it's very, very sensitive to how bright

26:22

it is out there and

26:25

then also what part of the world you're focusing

26:27

on, whether it's distance or near. So actually, if

26:29

you look up close, you'll

26:31

notice that your pupils actually get smaller and

26:33

also when you look in the distance, your

26:35

pupils get bigger. Sometimes eye

26:37

doctors do a test where they put some drops

26:40

into your eyes and it makes your pupils get

26:42

bigger and then everything looks kind of fuzzy for

26:44

a little while. What is that test about? Yeah,

26:47

so it's actually a difference. It's

26:50

a slight difference between kids and also

26:52

adults for why

26:54

we dilate. And

26:56

it's also one of the most anxiety

26:58

provoking things that a pediatric ophthalmologist does.

27:01

For the doctor or for the kids?

27:04

Yeah, for a doctor who's just learning

27:06

and also for the kids because

27:08

the kids will come in and they're wonderful

27:10

about being appreciative of coming in, but they

27:13

will talk about the drops all year long.

27:15

So what is the dilation about? So we

27:17

call it dilation, but it's actually two parts.

27:19

One is dilation and the other word is

27:22

psychoplegia, which is a big

27:24

fancy word, which means that we make it

27:26

so it's fuzzy. You can't focus up close.

27:28

So that's what those medications that are in

27:30

the drops do. They

27:33

make your pupil really, really

27:35

big, just like when it's really dark. And

27:38

the fancy word for that is dilation.

27:40

And then we make it so that

27:42

you can't focus up close. And the

27:44

fancy word for that is psychoplegia. And

27:47

the reason why we do both those things

27:49

is, one, I can catch the structures that

27:51

are in the back of the eye when

27:53

the pupil is larger. So that's one

27:56

helpful thing. And then the part where we make

27:58

it so that we can do it. it so you

28:01

can't focus, means that I can measure

28:03

your glasses prescription without you

28:06

neutralizing my measurements because

28:09

you're not able to focus. And that's what I

28:11

do after dilation. I can show you if you

28:13

like. I check

28:15

your glasses prescription with what's called a

28:17

retinoscope and it's this handheld

28:21

kind of thick looking

28:23

instrument with a square

28:25

top and basically

28:27

it creates a rectangular

28:30

light when we

28:32

turn it on and I can rotate the directions

28:34

that the beam is looking at

28:36

and I hold it up to my eye

28:38

with where the pupil is and then I

28:40

shine it in your pupil.

28:43

So it's very bright. Yes it is

28:46

and so I can see that actually you can kind

28:48

of guess your glasses prescription. You're a little bit nearsighted

28:51

with some astigmatism. Yes I am

28:53

well done. Thank you. I

28:56

was really impressed that Dr. Singh could look

28:58

into my eyes and know how my eyes

29:00

function. I kind of wish I could see

29:02

into my own eyes the same way she

29:04

could see into them. Wouldn't it be cool

29:07

to be able to look into your eyeball?

29:10

I'm nearsighted meaning I have trouble seeing

29:12

things clearly that are far away and

29:15

I have some astigmatisms which is when

29:17

your lens or cornea isn't shaped quite

29:19

right leading to blurry vision. Because

29:22

of those things I need glasses. Lots

29:25

of people wear glasses or contact lenses

29:27

to help them see better. They are

29:29

amazing inventions and we're going to

29:31

learn more about how glasses help people see

29:33

in our next episode where we continue to

29:36

hear about our amazing eyes and how they

29:38

function. Dr. Sajata Singh from

29:40

the University of Vermont Medical Center will

29:42

be back with us too answering all

29:44

of your amazing questions. If

29:47

you have a question about anything have your

29:49

adult send us a voice recording of you

29:51

asking it. You can do it

29:53

on a smartphone using a voice recorder or voice

29:55

memo app. Be sure

29:57

to include your first name, where you live and how

30:00

how old you are, and then

30:02

your adult can email the file

30:04

to questions at butwhykids.org. Or

30:06

you can find out all of this information

30:09

and submit your question directly at our website,

30:11

butwhykids.org. But

30:13

Why is produced at Vermont Public and distributed

30:15

by PRX. Our team includes

30:17

Melody Baudette, Kiana Huskin, and me, Jane

30:19

Lindholme. Our theme music is by

30:21

Luke Reynolds. We'll be back in

30:24

two weeks with an all-new episode. Until

30:26

then, stay curious. From

30:42

PRX.