Ophthalmologist Ashley Brissette, MD joins WIRED to answer your ocular enquires in a tech support all about eyes. How does LASIK eye surgery work? How does an eye doctor know if a baby needs glasses? What are ‘eye floaters’ and how do they work? What does an eyeball feel like? Dr. Brissette answers these questions and more—it’s Eye Support!
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TechTranscript
00:00 I'm ophthalmologist Ashley Brissett.
00:01 Let's answer some questions from Twitter.
00:03 This is eye support.
00:04 (upbeat music)
00:07 @EvanMurphy asks, "How does LASIK eye surgery even work?
00:12 "Like what?
00:13 "How does that just let you see?"
00:15 Well, I'll tell you how it works.
00:16 I perform LASIK and I even had LASIK done on myself.
00:18 What LASIK does is it helps to remove microscopic layers
00:21 of tissue on the surface of the cornea
00:23 to better direct the light as it enters the eye
00:26 so that it's focused in your retina.
00:27 The biggest risk is risk of infection,
00:29 although it's quite rare.
00:30 Less than one in 1,000 people
00:32 would ever develop an infection.
00:33 @JJDGMN asks, "What do eyeballs feel like?"
00:37 I mean, the closest thing I can think
00:38 that it feels like is a grape.
00:40 If you peel back a layer here,
00:41 you can see how delicate this tissue is.
00:44 So if you were gonna squeeze an eye,
00:45 it would kind of have the same squishy consistency
00:48 of a grape.
00:48 It's filled with a jelly, which is called the vitreous,
00:50 and then the tissue layers of the eye
00:52 are really, really thin,
00:53 almost like this thin outer layer of the grape.
00:55 When we're learning how to do surgery,
00:57 sometimes we practice certain techniques
00:59 on things like grapes.
01:00 @JuniorBarnaby asks,
01:01 "How do ophthalmologists know babies need glasses?"
01:03 One way we can tell that babies need glasses
01:05 is their eyes are crossing, turning in, or turning out.
01:08 Another reason we can tell that babies can't see
01:10 or might need glasses
01:11 is if they're rubbing their eyes a lot.
01:13 Sometimes babies rub their eyes a ton
01:15 'cause they're trying to stimulate vision.
01:16 Another reason is if babies are tilting their heads
01:19 or if they're not fixating on objects.
01:21 Usually by about three months,
01:23 babies should be able to see a toy or an object
01:25 and kind of fixate on it and follow it
01:27 if you move it around.
01:28 @MarksFisher asks,
01:29 "What is the anatomical purpose of eyelashes?"
01:31 Eyelashes actually exist to help trap all the dust,
01:35 pollution, bacteria, allergens that exist in the environment
01:38 so that they don't hit the surface of the eye.
01:40 It's actually proven that eyelashes
01:42 should be a specific length.
01:43 If your eyelashes are too long,
01:45 it's trapping too much of that in the environment
01:47 and it can sit there and cause irritation on the eyes.
01:50 That's why it's so important to be washing
01:52 over your closed eyelids every morning and evening
01:54 to remove all that's been trapped in the eyelids and lashes.
01:57 @TransReginaL asks,
01:59 "My right eye twitches.
02:01 Is this anxiety or nervousness?"
02:03 Twitching is what's called myokymia.
02:05 Eyelids switch for a number of reasons.
02:07 The most common is because of lack of sleep,
02:09 too much caffeine, or stress.
02:11 The muscles that are around the eye are very delicate
02:13 and very sensitive to stressors.
02:15 @RDabDao asks,
02:16 "What are the dangers of wearing contact lenses
02:18 while sleeping?
02:19 I always sleep with contacts on.
02:20 I don't see any side effects so far.
02:22 I have seen terrible damage to vision
02:24 from people that sleep in their contact lenses.
02:26 Our eyes get their oxygen from the environment.
02:28 And when you wear your contact lenses for too long,
02:30 you deprive the eyes of oxygen
02:31 and that can leave you really prone
02:32 to developing an infection.
02:34 And you can develop what's called a keratitis,
02:36 which is an infection on the cornea,
02:37 which is the surface layer of your eye.
02:39 Can lead to scarring and permanent damage to your vision."
02:41 @KevinClarkNW asks,
02:43 "Why does eyesight deteriorate with age?"
02:45 Eyesight deteriorates with age mostly due to cataract.
02:48 It happens to all of us as we get older.
02:50 The cataract is the clouding of the lens,
02:52 which is on the inside of the eye.
02:53 This gets more yellow, big, and thick
02:55 as we grow up.
02:56 And that changes the prescription
02:58 and also causes the vision to be blurry.
03:00 Cataract is actually the world's leading cause of blindness,
03:03 but it's reversible with a surgery.
03:04 It's actually the most commonly performed surgery
03:06 around the world.
03:07 I go inside the eye, remove the cloudy cataract,
03:10 and then put a new lens implant in its place
03:13 that has your prescription in it.
03:14 It's an artificial lens, but it's really well tolerated.
03:16 It's biocompatible and can help to restore vision.
03:19 @KeelNut wants to know, "What does 2020 vision mean?"
03:22 2020 vision refers to how we measure your vision
03:25 on a vision chart.
03:26 So most vision charts are set for 20 feet away.
03:29 If you can see the 2020 line,
03:31 that means that at 20 feet away from the eye chart,
03:33 you can read that line.
03:34 And we refer to that as normal or perfect vision.
03:36 About 35% of the population can only see that 2020 line
03:40 without glasses or contact lenses.
03:42 So say if you had 2050 vision,
03:44 which would be this line here,
03:46 what that refers to is that what you would be able to see
03:49 at 20 feet being this line here,
03:52 someone with perfect vision would be able to see
03:54 at 50 feet away.
03:55 Some people can even have better than perfect vision.
03:58 So we would refer to that as 2015 vision.
04:00 If you were standing at 20 feet from the eye chart,
04:03 the person with normal vision
04:04 would only be able to see what you see
04:06 if they stood closer at 15 feet to the eye chart.
04:09 @NoAmanoThotties asks, "What does legally blind even mean?"
04:14 Like, can you be illegally blind?
04:16 Like, can you get arrested for being [beep] blind?
04:18 So legally blind refers to vision that is 2200 or worse.
04:22 2200 is this big E on the chart.
04:25 If you're standing 20 feet away from the vision chart,
04:28 this is the only letter that you can read.
04:30 While somebody with perfect vision
04:31 would be able to stand 200 feet away
04:34 and also be able to read this E.
04:35 This would be vision of 2200.
04:38 @Nolsey27 asks, "Do carrots actually improve your eyesight
04:41 "or have my parents been lying to me my whole life?"
04:43 Carrots actually improve your eyesight.
04:45 They have beta carotene,
04:47 which is an important part of the vitamin A pathway.
04:49 There's actually big studies that we've done
04:51 that look at nutrients and how they affect your vision.
04:53 The main nutrients that are recommended
04:55 are vitamin A, vitamin C, vitamin E,
04:58 lutein, and zeaxanthin.
04:59 These vitamins that are recommended
05:01 are really important in the metabolic pathway
05:03 of the cells that are in your retina,
05:05 which is that vision sensory organ of the inside of the eye.
05:08 @AxieHuss wants to know,
05:10 "How do people know they're colorblind?"
05:11 You might know it's not right
05:12 because you'll start to sense
05:14 that there aren't as many differences in colors.
05:16 Most people who are colorblind,
05:17 it's not that they can't see color,
05:19 it's that colors are much more muted.
05:21 We can actually test it though.
05:22 These are what are called Ishihara color plates.
05:24 So if you're colorblind,
05:25 you might not see this red number six in the sea of green.
05:29 Similar to this one,
05:30 you might not be able to see the green S in the sea of red.
05:33 The most rare form of colorblindness is blue colorblindness.
05:37 So you might not be able to see the 10 here
05:39 in the sea of blue.
05:40 @Ferabee14 wants to know,
05:42 "Seriously though, where do eye floaters come from?"
05:44 Eye floaters are a natural part of the eye's anatomy.
05:46 Your eye is filled with a jelly, it's called the vitreous.
05:49 This jelly starts to liquefy as we grow up.
05:52 When it liquefies, you get clumps of cells and collagen,
05:54 which are in this jelly that clump together
05:56 and then cast a shadow on the retina.
05:58 So the floater that you're seeing moving around
06:00 is just kind of a clump of cells
06:01 in this now liquefied vitreous jelly,
06:03 casting a shadow in the back of your eye.
06:05 @misclaire18 asks, "Where do these tears come from?"
06:09 Tears come from the lacrimal glands.
06:11 It's a gland that is in the upper outer corner
06:13 of your eyelid.
06:14 The purpose of tears is to help keep your eyes lubricated.
06:16 Our eyes need to be lubricated for us to see clearly through.
06:19 That's why people that have dry eye
06:21 feel like their vision is blurry
06:22 and their eyes feel really uncomfortable.
06:24 @megstand asks, "I hate having to get my pupils dilated
06:27 "at the eye doctor.
06:28 "What is the purpose of that
06:29 "other than giving me a migraine?"
06:31 The reason we need to dilate your eyes
06:32 is to take a look inside the back of your eye.
06:35 As you can tell, the pupil,
06:36 it's really hard to see through it if it's small.
06:38 So by using the chemicals, phenylephrine and tropicamide,
06:41 they help to dilate that iris muscle
06:43 so that I can actually see into the back of your eye.
06:45 That's why it's so uncomfortable when you leave the office,
06:48 your pupils are really dilated,
06:49 so much light is getting through.
06:51 The way that I can see in the back of your eye
06:52 is by using a light on a microscope device such as this,
06:55 which can then magnify the view into the back of the eye.
06:58 We can tell a lot about your total body health.
07:00 So I can learn if you have high blood pressure,
07:02 if you have diabetes,
07:03 even sometimes some autoimmune conditions.
07:05 This is showing a normal eye.
07:07 This is the retina,
07:07 which is like the back wallpaper lining layer of the eye.
07:10 These are all the blood vessels,
07:12 which look really normal and healthy.
07:14 Here is the nerve.
07:15 That's the cable that connects the eye to the brain.
07:17 That sends the visual signals to your brain.
07:19 In contrast,
07:20 this is actually a photo of an eye with diabetes.
07:22 There's some bleeding spots.
07:24 The blood vessels look what we call tortuous,
07:26 which means that they're a little bit twisted.
07:28 And all of these yellow deposits here are swelling
07:30 or what we refer to as exudates.
07:32 As you can imagine,
07:33 all of this here can actually cause damage to the vision.
07:36 @cparty25 wants to know,
07:38 what's the difference between an ophthalmologist,
07:40 an optometrist, and an optician?
07:41 So an ophthalmologist goes to medical school.
07:44 They perform any medical procedures
07:46 and they do surgery on eyes as well,
07:47 such as LASIK, cataract surgery, glaucoma surgery.
07:50 Optometrists go to optometry school.
07:52 So they do general eye care,
07:54 glasses prescriptions, and contact lenses prescriptions.
07:56 And an optician is someone who makes the glasses.
07:58 @serena_males asks, are eyelash extensions safe?
08:01 So my answer is sometimes.
08:03 If you have the lash extensions on and they're too long,
08:05 it's keeping too much of the bacteria and dust and pollution
08:08 that gets trapped in them.
08:10 That just leads to bacterial overgrowth
08:12 and eventually infection.
08:13 I also see a lot of damage that people get
08:15 from the chemicals that are used
08:17 in terms of gluing them onto your natural lashes.
08:19 And sometimes I'm seeing people's natural lashes fall out
08:22 because of an issue with an allergy to the glue.
08:24 The lashes can grow back.
08:25 So if your eyelashes fall out,
08:27 it takes about two months for them to come back.
08:28 If you're really gonna play around with beauty trends,
08:30 only do it for a special occasion
08:32 and then give your eyes a break.
08:33 @leonpaz_ffxiv wants to know,
08:37 what's the difference between near and far-sighted?
08:39 Near-sighted is when you can see up close,
08:41 but it's really difficult to see far away.
08:43 That's actually the most common prescription error
08:45 that most people have.
08:46 Far-sighted is when you're able to see somewhat far away,
08:50 but really difficult seeing up close.
08:52 @alexisk97 asks, question for optometrists out there.
08:56 Why do I see shapes and colors when I rub my eyes?
08:58 What actually is that?
08:59 The eye is filled with a jelly.
09:01 And when you press on the eye,
09:02 the jelly then presses on the retina and it stimulates it
09:05 similar to like if light entered the eye to stimulate it.
09:07 This is where those rods and cones,
09:09 those photoreceptors are.
09:10 So it's why it's important not to be rubbing your eyes
09:12 'cause you're kind of just squishing your eyeball.
09:14 @dodgsonishere asks, I've never understood
09:16 how marijuana can be an effective treatment for glaucoma.
09:19 Like how is extreme paranoia supposed to help your eyes?
09:23 Marijuana is not a recommended treatment for glaucoma.
09:26 Yes, marijuana can have a very small,
09:28 very temporary effect of lowering your eye pressures.
09:31 We know that high eye pressure
09:32 is a risk factor for glaucoma,
09:34 but marijuana only lowers it
09:35 for a really short period of time
09:37 and not enough that it would actually be of any benefit.
09:39 @yasharchive wants to know, how did the eye tests work?
09:42 I mean, they do so many seemingly random things.
09:44 The first thing that we test
09:46 when you come for an eye exam is the vision.
09:47 So they'll flip back and forth
09:49 between the different prescriptions
09:50 to see what prescription do you actually need.
09:52 What these lenses do is they help to focus the light
09:55 so that it lands right on the back of the eye
09:57 so that it brings everything into focus for you.
09:59 Then we test your eye pressure.
10:00 That's that puff of air test
10:02 that everybody hates having done.
10:03 When the air puff test hits the front of the eye,
10:05 it's actually measuring how much it decompresses
10:08 the front of the eye and the rebound.
10:09 And that gives us a general sense of the pressure
10:11 on the inside of the eye.
10:12 We know that high pressure in the eye
10:14 can lead to damage in the nerve.
10:15 The nerve is the cable that connects your eye to your brain
10:18 and that's what gets damaged in glaucoma.
10:20 The last thing that we're gonna do
10:21 is look at your eyes underneath a microscope,
10:23 which is called a slit lamp.
10:24 It's this big machine.
10:25 You're gonna put your chin on the chin rest.
10:27 So we can actually look inside the back of your eye.
10:29 If the nerve is getting bigger,
10:31 that's a sign of glaucoma damage.
10:32 @phenomenal_nissa asks,
10:34 is the blue light filter actually good for eyes?
10:37 There was no evidence that using the blue light blockers
10:39 helped with eye strain with computer use.
10:41 It was a great marketing tool,
10:43 but a big research study came out
10:44 that showed no benefit for eye strain
10:46 using the blue light blockers.
10:47 Most of the eye strain occurs because of glare.
10:50 So you can get an anti-glare cover for your screen
10:52 and that can help.
10:53 @dpalmer216 asks, what kind of drugs is Zuckerberg on
10:56 that his pupils are always dilated?
10:58 I never noticed that
10:59 and I don't wanna get on his bad side,
11:01 but there's a few reasons why your pupils dilate.
11:03 One is if you're in dim lighting
11:04 and that's to allow more light to enter the eye.
11:06 Another reason pupils can dilate
11:08 is from some medications or some drugs,
11:10 stimulants such as cocaine, MDMA,
11:13 sometimes even some antidepressants.
11:15 It's a side effect of the medications.
11:16 Lastly, your pupils sometimes dilate
11:18 if you're in love or if you're aroused.
11:20 So if you see somebody that you love,
11:22 the pupils dilate
11:23 and that's because you get a release of dopamine
11:25 and the dopamine leads to the dilation.
11:27 @justsimplysally asks,
11:29 what happens when you look directly at the sun?
11:31 So you can sunburn your eyes.
11:32 UV damage can occur on the eyeballs.
11:35 It can cause something called photokeratitis,
11:37 which is a sun damage to the surface of the eye,
11:39 but it can also cause damage to the retina
11:42 in the back of the eye.
11:43 It damages those fine photoreceptors,
11:45 which are used for sensing vision.
11:46 If you look at the sun for say longer than 90 seconds,
11:49 that can cause this damage.
11:51 @flavorofgabby asks,
11:52 did you know that we actually see things upside down,
11:54 but the sensors that connect our brain and our eyes
11:56 flip the image?
11:57 Yes, I did know that.
11:58 And not only does it flip the image from up and down,
12:00 it also flips it from left to right.
12:02 Thinking of the eye like a camera,
12:04 it actually travels through the entirety of the eye.
12:06 The first thing it hits is the cornea,
12:08 which is the clear cover layer of the eye.
12:10 Then it travels through the lens,
12:11 which helps to direct the light rays into the macula,
12:14 which is the back part of your retina.
12:16 This nerve here is made up of 1.3 million little axons,
12:19 which are connections that allow the image
12:22 to be distributed through the brain
12:23 all the way into the back of your brain
12:25 called the occipital region.
12:26 So by having lots of different input,
12:28 lots of different connections from our visual world,
12:30 that helps to provide depth of field, depth of focus,
12:33 and gives you really great clarity for your vision.
12:35 Next question.
12:36 Is there a thing where your eyes can change color?
12:38 My eyes have never been this light before.
12:40 Your eye color is pretty set by about one year of age.
12:43 Your eyes can appear to look different colors.
12:45 It usually has to do with the amount of lighting,
12:48 colors that you're wearing.
12:49 The reason why people have different eye colors
12:51 is the amount of melanin or pigment in their iris,
12:53 which is the colored part of the eye.
12:55 So people with blue eyes have less melanin
12:57 and people with brown eyes have more melanin.
12:59 At OnlyOneLVM asks, how do people become cross-eyed?
13:02 We call this strabismus.
13:03 Strabismus means a turning in or a turning out of the eye.
13:06 You have to be able to see clearly for your brain
13:09 to use the two eyes together.
13:10 And if one of the eyes isn't seeing very well,
13:13 then the brain starts to ignore one of the eyes,
13:15 ignores those muscles, and the eye starts to drift or turn.
13:18 So those are all the questions for today.
13:19 Those were some really great questions.
13:21 My biggest pieces of advice,
13:22 make sure you're washing over your closed eyelids,
13:25 eating well, and just stay healthy.
13:26 Thanks for watching Eye Support.
13:28 [Music]