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[[quoteright:250:[[WesternAnimation/MyLittlePonyFriendshipIsMagic http://static.tvtropes.org/pmwiki/pub/images/rsz_1spikeiris3_3880_6384.jpg]]]]

Normally, the eye filters light by widening or closing the hole in the center of the iris, called the pupil. Emotional reactions can achieve this as well: shock might narrow the pupil, while relaxing could widen it considerably. However, in animated fare or ComicBooks, this can be very hard if not impossible to show, since a typical human pupil, at its widest, is 3-4 millimeters.[[note]]For the metric-impaired, that's 0.12-0.16 inches.[[/note]] This trope is a way to sidestep that difficulty. Instead of just changing the size of the ''pupil'', you change the size of the ''iris'' (the colored ring surrounding the pupil) as well.

Your iris is no more capable of growing than your bones are of [[RubberMan stretching like Gumby]], but since they are by far the largest feature of an eye other than the whites, it's easy for artists to "expand" them to get the desired emotional reaction across.

The opposite, when the irises are drawn in a shrunken state to indicate fear, pain, or shock is WideEyesAndShrunkenIrises. Compare ExpressiveMask. Not to be confused with IrisOut.

When the pupils are drawn abnormally large, the eyes generally appear pleading or wistful. That trope is PuppyDogEyes.

Opening the [[TeleFrag iris]] in ''Series/StargateSG1'' has nothing to do with this trope. See DilatingDoor for doors like that.


[[folder: Anime and Manga]]
* The animation style of ''Anime/MagicalGirlLyricalNanoha'' usually shows an all-black pupil/iris with the anime-standard lens flare and a cresent of color near the bottom of the eye. When a character is shocked, scared, or incredibly pissed off, you can see the iris all the way around. [[WideEyesAndShrunkenIrises Their eyes kind of shrink, too.]]
* Since just about every main character in ''Manga/PeacemakerKurogane'' spends a lot of time indulging in {{Angst}} over past and/or current traumatic events this happens often. (The most notable characters who do this are Tetsunosuke and Suzu.)
* Done in many {{Reaction Shot}}s in ''Anime/SerialExperimentsLain''.
** Similarly used in ''Anime/GhostHound'', by the same director.
* In a particularly extreme example, in ''Magikano'', the iris opens, then the iris and pupil shrink, and the sclera ''fractures''.
* This is used along with HellishPupils in ''VisualNovel/HigurashiWhenTheyCry'' - probably because [[spoiler:any character with this effect is usually in the grip of some serious paranoia]].
* Train from ''Manga/BlackCat'' does this a LOT. Though, even for anime standards, his irises were already not normal, looking a lot more like a cat's. Creed also does this sometimes.
* It happens occasionally to Sousuke from ''LightNovel/FullMetalPanic'', though not too often, considering how normally [[TheStoic unphasable]] he is. He's shown doing this more often during ''TSR'', and it's noticeable in the ''Sigma'' manga [[http://www.mangafox.com/manga/full_metal_panic_sigma/v02/c007/21.html as well]].
* People in ''Anime/MobileSuitGundamSEED'' who enter SEED Mode have much larger irises, though their emotional range typically doesn't change much.
* In ''Manga/{{Naruto}}'', this is what the 9-Tailed Fox looks like when [[spoiler:it's being controlled by someone with the Sharingan]].
* ''Manga/BabySteps'': This technique is used to reflect Eiichirou's shock when Kageyama suggests he knows the reason E-chan got into tennis.
--> '''Kageyama''': "...you like Takasaki-san, don't you!?"
--> '''Eiichirou''' (his irises shrinking to tiny dots): "EEEEEEEHHHHHH!?!?!"
--> '''Kageyama''': "What's with that reaction?"
* [[Manga/ChisSweetHome Chi]]'s irises got HUGE when she saw a shopping bag filled with kitty toys. Of course, [[KidsPreferBoxes she went straight for the bag.]]

* ComicBook/{{Concrete}} can actually do this with his eyes, dilating them until there's nothing but the black of the pupils visible in order to see in the dark. According to ''Under the Desert Stars'' his eyes "dilate enormously, adding light-gathering power to their high resolution", though in a later story Maureen described his night-vision as being similar to that of a cat or dog (which doesn't explain at all why they turn black), so the original explanation of how they work may or may not have been [[RetCon retconned]].

* Tweaked in 2004's ''Film/DawnOfTheDead2004''. When the anonymous woman reanimated, we got a closeup shot of her eye turning from normal human green to that freaky occluded color.
* Happens a lot in horror movies, when a person who's a vampire/possessed/under a spell goes from looking normal human to looking like they're a vampire/possessed/under a spell.

* In J.R.Ward's ''Literature/BlackDaggerBrotherhood'' paranormal romance series, the [[OurVampiresAreDifferent vampire]] {{seer|s}} [[NamesToRunAwayFromReallyFast character]] [[SpellMyNameWithAnS Vishous]] has this happen to his left eye whenever he deliberately tries to look into someone's future or to [[LaserGuidedAmnesia bury their memories]].

* A prominent visual in Music/LadyGaga's video "Music/BadRomance."

[[folder:Theme Parks]]
* ''Ride/TheFuntasticWorldOfHannaBarbera'' had Shaggy due this when he sees the ride vehicle very-nearly crash into the Mystery Machine.

* ''Webcomic/DominicDeegan'' features irises getting huge and limpid when someone is feeling touched or romantic toward someone else.
* ''Truck Bearing Kibble'' in [[http://truckbearingkibble.com/comic/2007/02/16/the-litteroo/ this strip]]
* Happens to ''Creator/KateBeaton'' when she's [[http://beatonna.livejournal.com/83621.html traumatized by James Joyce's love letters.]]
* In ''Webcomic/{{Blip}}'', Hester's irises are massive by default, larger than any other characters' (it's even {{lampshaded}} [[http://blip.rampagenetwork.com/22/ early on]]); a visual indication that she's the most emotional of the bunch.
* ''WebComic/{{Homestuck}}'': In the end-of-Act-5 flash, Rose comes to a sudden realization about [[BatmanGambit the nature of The Tumor]]. Her eyes widen as the camera zooms in on them for dramatic effect, and then everything goes ''wrong''.
* In ''Webcomic/RustyAndCo'', [[http://rustyandco.com/comic/level-6-25/ even in minature, we can see how white Madeline's eyes get what she sees what Cube is doing.]]
* ''Webcomic/BearNuts'' makes heavy use of this.

[[folder: Western Animation]]
* Common trope in WesternAnimation, especially happening to children when they are surprised by something (to the perspective of a kid) mortifying. Used at least once in nearly every {{Creator/Nickelodeon}} and Creator/CartoonNetwork show.
* Common trope in ''WesternAnimation/TheFairlyOddParents''.
* ''WesternAnimation/AvatarTheLastAirbender''
** "The Desert"
---> '''Sokka:''' Driiiink [[MushroomSamba cactus juice!]] It'll quench ya! Nothing's quenchier! It's the quenchiest!
** "Lake Laogai"
---> '''Long Feng:''' [[ManchurianAgent The Earth King has invited you to Lake Laogai.]]
---> '''Jet:''' I am honored to accept his invitation.
* In ''WesternAnimation/KimPossible: So The Drama'', Kim's iris and pupil go bigger, then smaller when she is shocked [[spoiler: by her android boyfriend who works for Drakken and Shego]].
* ''WesternAnimation/TheSpectacularSpiderMan'' plays with the trope. Curt Connors' iris ''narrows'' to a vertical slit, then opens back up to a normal human one. Well, sort of. None of the people in this AnimatedSeries ''have'' pupils, just irises.
* In ''WesternAnimation/TheSimpsons'', this is one of Homer's reactions as he chows down on Krusty Burger's barbecue sandwiches, repeated along with the action itself and fat and suchlike flooding into his system (a ShoutOut to ''Film/RequiemForADream'').
** Also, when he [[ToadLicking licks hallucinogenic toads]].
** In general, this is the way Simpsons characters show that a psychoactive drug/medication is kicking in. ''{{WesternAnimation/Futurama}}'' uses the trope in the same way.
* ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' provides the page image. The animation uses eye tropes heavily to convey emotions, and Open the Iris is used to show, just for example, epiphany, wonder, greed, insanity, terror, emphasis of a key phrase, and the sensation of [[ItMakesSenseInContext burping up a scroll]].
* In ''WesternAnimation/SpongeBobSquarePants'', Gary gets this when Spongebob informs him it's time for a bath...though in his case, his pupils growing bigger means he's ''scared.''
* Happens to [[EverythingsEvenWorseWithSharks Bruce]] in ''WesternAnimation/FindingNemo'' as a result of him suddenly reverting back into "a mindless eating machine" after accidentally sniffing Dory's blood.
* In ''WesternAnimation/LittlestPetShop2012'' this happens to many of the characters at times, but for the most part everyone's eyes are already so huge that this trope is almost unnecessary.
* In the ''WesternAnimation/DextersLaboratory'' short "Chicken Scratch" Dee Dee sees Dexter with chicken pox and this happens to her.
* JusticeLeagueUnlimitedS2E4TaskForceX: Plastique’s iris narrows every time she has a OhCrap moment.
* ''WesternAnimation/SantaClausIsCominToTown'': Kris gets these when he sees the Winter Warlock for the first time.