Anime Eyes

Anime eyes

anime eyes
Classic anime eyes

First off sorry for the lack of posting lack week, but I went to Lake Khuvsgul and came down with the flu and it took me a while to recover. Anyway I’m back to full health and lets get on with the science, specifically anime eyes.

Even the most casual observer of anime will notice that anime eyes are very different when compared to other styles of animation. These differences can include shape, size, color, and other anomalies. However, the most noticeable of these are size, and color. Before I delve into the science, first we need a quick look at some cultural factors that have influenced eye shape in anime eyes.

Modern popular culture in Japan is obsessed with cute things, and this is blatantly obvious in Akhihabara (electric town, or Otaku Mecca), and in other areas of the country many, of which have their own cute little mascots. This has influenced the animation as babies are decidedly cute and their eyes do appear to be larger. This is due to the fact that at birth the human eye is around 75% of its final size, so they do grow during life, but not as much. At the same time the skull is considerably smaller as a percentage of final size. This makes the eyes appear to be much larger than they are.

Secondly, there is the saying, “the eyes are the window to the soul.” While this is a fairly common saying in the West, it is one that the Japanese like as well. In Japan this metaphor is used visually to show how open minded and gentle a person is. Therefore younger, more naïve characters have larger eyes, specifically the pupils, as a way to represent that aspect of their personality. The older and more antagonistic characters tend to have narrower smaller pupils. We can see this by looking at the eyes of one Ryoko Habuki from Tenchi Muyo.

Evil Ryoko
Small eyes
Good Ryoko after some character development
Larger eyes

Enlarged eyes in the real world

You might occasionally run into someone with what, for intense and purposes, looks like enlarged eyes, but in reality the eyes aren’t enlarged at all. In this case the eyes are being pushed forward due to swelling. What I am referring to is Graves’ ophthalmopathy, which is an autoimmune disease that causes swelling behind the eyes pushing them out of place. It can be rather painful and is associated with vision problems.

anime eyes in real life
Enlarged eyes in real life

Other eye structures

Anime characters can also have other parts of their eyes enlarged such as the iris and pupil.

anime eyes
Yui from K-on

In this case you can see that Yui’s iris covers almost her entire eye and her pupil is also extremely large. An enlarged iris is extremely uncommon in us real world people with only one condition that could potentially cause the iris to enlarge, a diffuse iris melanoma. Even then the change is size is minimal. This usually results in the removal of the eye, but there are some new radiation treatments that might spare it.


Enlarged pupils are a different story as our own pupils do change size in regards to the amount of light our eyes are exposed to, narrowing in response to bright light, and expanding in response to low light. This also happens in anime eyes, but Japan tends to take it a bit too far.

anime eyes

If you have ever been to the eye doctor, you were probably given eye drops to dilate your pupil larger than normal so the doctor could examine certain structures within the eye. However, having a dilated pupil outside of the eye doctor’s office is a very worrisome sign as it is an indication of a major brain injury. Therefore, in medical shows a nurse or doctor will remark that the patient’s pupils are fixed and dilated, which is an indicator of brain death.


Yes, you can have anime eyes…… but you really wouldn’t want to since that would mean you have any number of severe medical conditions and/or be dead.


Eye color

Beyond size anime eyes are also well known for their wide array of colors.

anime eye color

In humans, eye color is determined by the pigmentation of the iris, which is determined by a dihybrid inheritance system, which means that two different genes are working in concert. While the shade of color might vary slightly, the possible human eye colors are amber, blue, brown, gray, green, hazel, red, and violet.

human eye color

I know what you are thinking, that red eyes are not possible. Well, they are if you have albinism, which is a complete lack of skin pigmentation, as the pigment in our skin is also in our eyes. This means the iris in a person with albinism would be completely clear and the red color is from the blood vessels at the back of the eye, normally masked by a pigmented iris. As to some of the more wild colors seen in anime eyes, please refer to my post on anime hair color, where I explain that many of these colors are found in nature, just not in people.


My final answer here is the same one I gave in anime hair color. Humanity is always evolving, so who is to say what can happen in the future. We might just see some more interesting eye colors.


Other eye conditions

Heterochromia is a condition where the iris of each eye is a different color as exemplified by Vivio, seen below.

This is actually a real, if rather rare, condition found in some people with a variety of causes, including viruses, and genetics.



Yes I know, Naruto again, but the long running series is just rife with little tidbits of biology, just waiting to be poked at with the biological stick. This is especially true in regards to eyes, the Sharingan, Byakugan, and Rinnegan. For anyone who doesn’t know, the Sharingan and Rinnegan are identified in part by dark rings around the iris.

Anime eyes

Obviously I am not going to be talking about all of the supernatural powers these anime eyes grant, since this is a science blog, but there is still something worth talking about. The rings, yes, the rings, as there is a real-world condition called Kayser-Fleischer Rings, which are dark rings around the iris.

These rings are caused by Wilson’s Disease, which is a genetic disease that affects the liver and nervous system. The disease causes copper to build up inside the body, and one of the symptoms are the rings seen above.

Next we need to cover the Byakugan, which allows for 360 degree vision except for a small blind spot over the 1st thoracic vertebra. It is of course impossible for humans to see 360 degrees at once; a few animals have larger fields of vision than humans, but their eyes are set more on the side of the head. The fact that the Byakuganhas a blind spot is actually scientifically correct and normal humans also have a blind spot. This blind spot is called the physiological blind spot and there are a number of videos that can walk you through how to find it. The blind spot itself is caused by the optic nerve connecting to the retina (detects light) At this particular spot there are no cells that detect light, hence the blind spot. We do not notice this in our daily lives since our visual fields of view overlap and the opposite eye covers for the other’s blind spot.

Blind spot


I came across an interesting article while doing some research for this post, and it offers another interesting take on the overly large eyes seen in anime. Neanderthals, an extinct, but very recent ancestor or offshoot of humanity, depending on the scientist, has larger eyes than homo sapiens (humans).

Homo Sapien (left) vs Neanderthal (right)

So perhaps in some of those anime worlds there is a bit more Neanderthal in some people, causing them to have slightly larger eyes than others. There is also some debate that this could have led to a lower ability in social situations due to how the brain could be structured to handle the extra visual information coming from larger eyes. So, there could be a physiological reason behind that socially awkward large eyed anime girl.

FYI- if you are interested in the development of the eye and depth perception check out this post on Manako the cyclops from Everyday Lives with Monster Girls.
Thanks for reading and if you have any comments or questions please leave them in the comments section below.

4 thoughts on “Anime Eyes

  1. Pingback: Anime Science 101- Interviews with Monster Girls- Hikari the Vampire

  2. Thescarredman says:

    I’d like to see an expansion of the ‘anime eyes’ section to include the various eye shapes found in anime, which are supposed to denote various personality traits. Where did these shape conventions come from, and do they have roots in real life?

    • Anime Science 101 says:

      It will take some time TSM, but I will see what I can do. Preliminary research hints at it originating in China

  3. Pingback: Anime Science 101- Everyday Life with Monster Girls- Manako the Cyclops

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