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How fast the human eye can [temporarily] change its color?

How fast the human eye can [temporarily] change its color?


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I know that human eye can change its color during lifetime because of disease or medication (similar question on Biology.SE). And I know that it may change depending on the lighting.

But I saw several times as the eyes of man with the bright eyes changed color (blue/gray/green) without changing environment. Is it possible to temporarily change eye color due to the change of emotional state (as a consequence of the effect of hormones or something else) in just a few of minutes? If so, what are the processes behind this?

Or it just optical/psychological illusion for the observer?


Is it possible to change your eye color?

Genetics determine the color of the eyes, which often darkens in the first few years of life. As a person ages or the lighting shifts, eye color can change slightly, but some people seek lasting, significant adjustments.

If a person wants to change their eye color temporarily, this is most often accomplished with contact lenses. There are many types available that provide different effects.

For people hoping to alter their eye color permanently, iris implant surgery is available. However, due to the severe associated risks, many doctors discourage this option.

In this article, we describe how eye color develops and the most common ways to change it, temporarily or permanently.

Share on Pinterest A person’s eye color is determined by their genes.

The iris is the colored portion of the eye.

  • brown
  • black
  • green
  • blue
  • hazel
  • a mixture of these colors

A combination of the parents’ genes determines the color of the iris. Because of the many possible combinations, the eye color of a child may not match that of either parent, making it nearly impossible to predict.

Eye color can change over time, but only slightly.

The eye color of most babies will darken in the first few years of life. During this time, the body produces a darker pigment, known as melanin.

Expansion or contraction of the iris can also lead to minute changes in eye color.

This can occur when a person:

  • focuses the eyes
  • spends time either in very dark or brightly lit areas
  • experiences strong emotions

People sometimes notice that their eye color lightens with age. This is natural and should not be a cause for concern.

Using tinted contact lenses is the most common way to change eye color for a short time.

Three types of lenses are available, depending on how drastic a change is desired. They include:

Visibility lenses

These are lightly tinted, and will only have a small effect if a person’s eyes are very light in color.

Visibility lenses are tinted to help people see whether their lenses are in their case. The tinting also helps a person to find them if they are accidentally dropped.

Enhancement lenses

Enhancement lenses are semiopaque.

They do not fully alter the color of the eye, but they can intensify it, making it stand out more.

Opaque lenses

On these lenses, the iris is colored in fully, allowing a person to change their eye color completely.

Opaque lenses come in a variety of colors, including:

Risks of using contact lenses

As with corrective lenses, decorative lenses have certain risks. Failing to clean and care for contact lenses can, in some cases, result in blindness, as well as other eye issues.

The Food and Drug Administration (FDA) in the United States require a prescription for cosmetic lenses. This means that all contacts, even decorative lenses, sold legally are fitted by an optometrist or ophthalmologist, to reduce the risk of complications.

The organization warns that buying lenses without a prescription increases the risk of developing:

  • itchy, watery eyes
  • blurry vision
  • a scratched cornea
  • partial vision loss or blindness

Whether they are tinted or clear, purchase contact lenses from sources that require or offer a prescription and are FDA-approved.

Also, the FDA recommend using the same care toward decorative lenses that a person uses on corrective lenses. This will help to avoid complications.

In some parts of the world, iris implant surgery is available.

It was developed to repair or replace the iris following illness or trauma. However, because it can provide a permanent change in eye color, it is becoming popular among people seeking purely cosmetic changes.

Many risks are associated with this surgery. Authors of a small study found that people who underwent iris implant surgery for cosmetic reasons were likely to experience complications, such as:

  • eye inflammation
  • swelling of the cornea
  • injury to the cornea
  • partial vision loss or blindness

Iris implant surgery in the U.S.

This type of surgery is not currently legal in the U.S. Clinical trials that could confirm its safety have yet to be performed.

Does honey and tepid water work?

Some people promote the use of honey and tepid water to change the color of the eyes gradually. No scientific evidence supports this method, and it is not considered safe. Tap water and honey are not sterile and can cause infection.

If the color of one or both eyes changes suddenly and significantly, see an eye doctor as soon as possible.

It is particularly dangerous for eyes to change from brown to green, or from blue to brown.

Major changes in the iris’ pigment can indicate illness, such as:

  • Horner’s syndrome
  • Fuchs heterochromic iridocyclitis
  • pigmentary glaucoma
  • iris melanoma

All require medical treatment and care.

People using decorative lenses should see a doctor if they experience the following eye-related symptoms:

Anyone who experiences changes in vision after undergoing iris implant surgery should see a doctor as soon as possible.

Decorative, or cosmetic, lenses provide the safest and quickest way to change the color of the eyes.

Buying lenses from a reputable source, having them fitted by a doctor, and exercising proper care can reduce associated risks.

Anyone seeking a more permanent change in color and considering surgery should be aware of the many severe risks. It is not considered a viable option.


Why does it take my eyes several minutes to adjust to darkness?

One of the most amazing things about human vision is the incredible range it has. We can see in very bright sunlight, and we can also see in nearly total darkness. ­If you spend much time working with a camera, you know how amazing this range is. Film that works well outdoors is nearly useless indoors, and vice versa. The range that our eyes have comes from three different parts of the eye:

Pupil The pupil contracts and expands depending on the amount of light, and can physically block the amount of light entering the eye in bright situations.

  • Rod and cone cells in the retina - Our eyes sense light with two different types of cells: rods and cones. Cone cells can perceive color in bright light. Rod cells perceive black and white images and work best in low light.
  • Rhodopsin - Rhodopsin is a chemical found in the rods.

­Rhodopsin is the key to night vision -- it is the chemical that the rods use to absorb photons and perceive light. When a molecule of rhodopsin absorbs a photon, it splits into a retinal and an opsin molecule. These molecules later recombine naturally back into rhodopsin at a fixed rate, and recombinati­on is fairly slow.

So, when you expose your eyes to bright light, all of the rhodopsin breaks down into retinal and opsin. If you then turn out the lights and try to see in the dark, you can't. The cones need a lot of light, so they are useless, and there is no rhodopsin now so the rods are useless, too. Over the course of several minutes, however, the retinal and opsin recombine back into rhodopsin, and you can see again.

A fun fact: The retinal used in the eye is derived from vitamin A. If a person's diet is low in vitamin A, there is not enough retinal in the rods and therefore not enough rhodopsin. People who lack vitamin A often suffer from night blindness -- they cannot see in the dark.


The Human Eye's Response to Light

The three curves in the figure above shows the normalized response of an average human eye to various amounts of ambient light. The shift in sensitivity occurs because two types of photoreceptors called cones and rods are responsible for the eye's response to light. The curve on the right shows the eye's response under normal lighting conditions and this is called the photopic response. The cones respond to light under these conditions.

As mentioned previously, cones are composed of three different photo pigments that enable color perception. This curve peaks at 555 nanometers, which means that under normal lighting conditions, the eye is most sensitive to a yellowish-green color. When the light levels drop to near total darkness, the response of the eye changes significantly as shown by the scotopic response curve on the left. At this level of light, the rods are most active and the human eye is more sensitive to the light present, and less sensitive to the range of color. Rods are highly sensitive to light but are comprised of a single photo pigment, which accounts for the loss in ability to discriminate color. At this very low light level, sensitivity to blue, violet, and ultraviolet is increased, but sensitivity to yellow and red is reduced. The heavier curve in the middle represents the eye's response at the ambient light level found in a typical inspection booth. This curve peaks at 550 nanometers, which means the eye is most sensitive to yellowish-green color at this light level. Fluorescent penetrant inspection materials are designed to fluoresce at around 550 nanometers to produce optimal sensitivity under dim lighting conditions.

References: Robinson, S. J. and Schmidt, J. T., Fluorescent Penetrant Sensitivity and Removability - What the Eye Can See, a Fluorometer Can Measure, Materials Evaluation, Vol. 42, No. 8, July 1984, pp. 1029-1034


Why Do Many Think Human Blood Is Sometimes Blue?

Blood is red to the naked eye. Under a microscope, it depends.

This isn't because it isn't really red, but rather because its redness is a macroscopic feature. Human blood is red because hemoglobin, which is carried in the blood and functions to transport oxygen, is iron-rich and red in color.

Octopuses and horseshoe crabs have blue blood. This is because the protein transporting oxygen in their blood, hemocyanin, is actually blue.

The blood of a vulcan is green, according to the story anyway, and this is presumably because the stuff that carries oxygen in the vulcan's blood is green.

But our blood is red. It's bright red when the arteries carry it in its oxygen-rich state throughout the body. And it's still red, but darker now, when it rushes home to the heart through the veins.

I bring this up because I've noticed that there are a fair number of people — some of the 7th graders my son goes to school with, some teachers, too, who ought to know better, as well as lots of people who have published online — who say that blood inside the body is sometimes blue.

Here is some evidence that this isn't true.

When I was 12, I was in an accident and my left wrist was ripped open so that I could see into my arm. Everything was red. Blood was shooting out of my arteries and sloshing out of my veins. And all of it was red.

Here's another piece of evidence. If you get blood drawn, the liquid that comes from your vein into the vacuum sealed container is, plainly, red.

We also know why it is red, as already noted. It's red because of the red blood cells (hemoglobin). Blood does change color somewhat as oxygen is absorbed and replenished. But it doesn't change from red to blue. It changes from red to dark red.

It is true that veins, which are sometimes visible through the skin, may look bluish. Why should this be so? Click here if you want the full story. But the short of it is this: It has to do with the way tissue absorbs, scatters and reflects light. (I think this also explains why your lips look blue when you get cold.) But if you were to open one of your veins, or cut your lip, even when you're cold, there'd be nothing blue at all about the liquid that would pour forth.

Maybe it is the fact that veins look bluish that explains the myth that blood is blue as it flows through the veins?

Or could the answer lie elsewhere? By convention arteries are drawn red in textbooks and veins blue. Could it be that people have taken this to be a guide to their actual color?

I think this is worth understanding. It's a politically neutral example of a bit of falsehood that seems resistant to information. At a time when ignorant people openly challenge scientific knowledge about such important matters as the safety of vaccines or the dangers posed by the burning of fossil fuels, it seems worthwhile to try to understand why some bad ideas are so immune to revision.

Here's a hypothesis: The problem is not outright ignorance. You can imagine children — who may have never seen an accident, or been cut, or had blood drawn or taken a biology class — who might gullibly believe that blood is blue, because someone told them so. Even people who have been cut, or have witnessed an accident scene, or had blood drawn, cleave to the conviction of blood's sometime blueness. Such conviction and confidence when everything — when all the evidence — speaks loudly against, can only be the result of some prejudice or bias. But what? Why?

A little knowledge, it turns out, can be a dangerous thing. It's hard to disprove a falsehood when it seems to fit so seamlessly with other true, if poorly understood, propositions. That's what's going on here, it would seem. Take a little blood chemistry, exposure to textbooks and the sight of your own naked arms, and you get a perfect ecosystem in which to nourish a manifestly false belief.

Thanks to Ulysses Noë for adding to this discussion.

Alva Noë is a philosopher at the University of California, Berkeley where he writes and teaches about perception, consciousness and art. He is the author of several books, including his latest, Strange Tools: Art and Human Nature (Farrar, Straus and Giroux, 2015). You can keep up with more of what Alva is thinking on Facebook and on Twitter: @alvanoe


Changes in Eye Color

The color of our eyes is determined by the amount and color of pigment granules, called melanin. These granules vary in color from a neutral tone to very dark brown, with darker eyes caused by darker melanin or a greater degree of melanin, and vice-versa. The color of the iris is caused by pigment in the stroma (the connective tissue of the front layer of the iris), and this color can lighten if the amount of pigment granules in the stroma decreases, or if the granules produce lighter pigment. Unlike skin and hair, eyes don’t synthesize color pigment all the time, but retain the accumulated pigment in the stroma. If the pigment degrades over time, this can result in a lightening of eye color.

  • The color of our eyes is determined by the amount and color of pigment granules, called melanin.
  • Unlike skin and hair, eyes don’t synthesize color pigment all the time, but retain the accumulated pigment in the stroma.

Mantis shrimp's super colour vision debunked

One of the animal kingdom’s most complex eyes is really quite simple.

Mantis shrimp don’t see colour like we do. Although the crustaceans have many more types of light-detecting cell than humans, their ability to discriminate between colours is limited, says a report published today in Science 1 .

Researchers found that the mantis shrimp’s colour vision relies on a simple, efficient and previously unknown mechanism that operates at the level of individual photoreceptors. The results upend scientists' suspicions that the shrimp, with 12 different types of colour photoreceptors, could see hues that humans, with just 3, could not, says study co-author Justin Marshall, a marine neuroscientist at the University of Queensland in Brisbane, Australia.

When the human eye sees a yellow leaf, photoreceptors send signals to the brain announcing relative levels of stimuli: receptors sensitive to red and green light report a lot of activity, whereas receptors sensitive to blue light report little. The brain compares the information from each type of receptor to come up with yellow. Using this system, the human eye can distinguish between millions of different colours.

To test whether the mantis shrimp, with its 12 receptors, can distinguish many more, Marshall's team trained shrimp of the species Haptosquilla trispinosa to recognize one of ten specific colour wavelengths, ranging from 400 to 650 nanometres, by showing them two colours and giving them a frozen prawn or mussel when they picked the right one. In subsequent testing, the shrimp could discriminate between their trained wavelengths and another colour 50–100 nanometres up or down the spectrum. But when the difference between the trained and test wavelengths was reduced to 12–25 nanometres, the shrimp could no longer tell them apart.

If the shrimp eye compared adjacent spectra, like the human eye does, it would have allowed the animals to discriminate between wavelengths as close as 1–5 nanometres, the authors say. Instead, each type of photoreceptor seems to pick up a specific colour, identifying it in a way that is less sensitive than the human eye but does not require brain-power-heavy comparisons. That probably gives the predatory shrimp a speed advantage in distinguishing between different-coloured prey, says Roy Caldwell, a behavioural ecologist at the University of California, Berkeley.

Michael Bok, a biologist at Lund University in Sweden who studies vision, says that the work is an important step towards understanding the incredible complexity of the mantis-shrimp eye. “The next step, really, is to figure out what these visual signals tell the brain and how the brain uses these signals.”


Generating Another Energy Carrier: NADPH

The remaining function of the light-dependent reaction is to generate the other energy-carrier molecule, NADPH. As the electron from the electron transport chain arrives at photosystem I, it is re-energized with another photon captured by chlorophyll. The energy from this electron drives the formation of NADPH from NADP + and a hydrogen ion (H + ). Now that the solar energy is stored in energy carriers, it can be used to make a sugar molecule.


Eye Cancer (Ocular Melanoma)

If you have eye cancer (ocular melanoma) or are close to someone who does, knowing what to expect can help you cope. Here you can find out all about ocular melanoma, including risk factors, symptoms, how it is found, and how it is treated. (For information on the most common type of eye cancer in children, see Retinoblastoma. For information about intraocular lymphoma, see Non-Hodgkin Lymphoma.)

About Eye Cancer

Get an overview of eye cancer and the latest key statistics in the US.

Causes, Risk Factors, and Prevention

Learn more about risk factors and prevention of eye cancer (ocular melanoma).

Early Detection, Diagnosis, and Staging

Learn about the signs and symptoms of ocular melanoma. Find out how eye cancer is tested for, diagnosed, and staged.

Treating Eye Cancer

If you are facing eye cancer, we can help you learn about the treatment options and possible side effects, and point you to information and services to help you in your cancer journey.

After Treatment

Get information about life as a cancer survivor, next steps, and what you can do to help.


A Word From Verywell

Color can play an important role in conveying information, creating certain moods, and even influencing the decisions people make. Color preferences also exert an influence on the objects people choose to purchase, the clothes they wear, and the way they adorn their environments.

People often select objects in colors that evoke certain moods or feelings, such as selecting a car color that seems sporty, futuristic, sleek, or trustworthy. Room colors can also be used to evoke specific moods, such as painting a bedroom a soft green to create a peaceful mood.

So what's the bottom line? Experts have found that while color can have an influence on how we feel and act, these effects are subject to personal, cultural, and situational factors. More scientific research is needed to gain a better understanding of color psychology.


Watch the video: The Moment in Time: The Manhattan Project (October 2022).