The discussion of the anatomy and evolution of eyes. Consider using the "vision" tag for questions regarding how the brain interprets information from the eyes.

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8
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1answer
237 views

Is it a limitation of the eyes, or the brain, that we can't see a moving bullet?

Are the photoreceptors in our eyes not fast enough to register the fast moving bullet, or is the brain not powerful enough to make sense of something happening that fast?
10
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1answer
621 views

How does laser surgery correct accommodation problems?

When someone undergoes laser surgery to improve eyesight, how does it correct accommodation problems? Why does it not help presbyopia?
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1answer
68 views

Why do eyes water in response to particular emotions?

It is common for people to experience very moving situations (sad movies, etc) and have a physical reaction to it (such as crying). I am curious about how emotions can physically lead to the act of ...
7
votes
1answer
721 views

Why do human eyes glow red on a photo and dog's eyes green?

Previous Research I know that cameras sometimes come with an anti "red eye" functionality that involves two flashes, presumably the second flash coincides with the shutter opening. Question Why do ...
9
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1answer
1k views

How does this illusion work?

I found this image on Google+ If you shake your head you can see a portrait of a person. Can anyone explain how the image is constructed in the brain?
8
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2answers
32k views

Which shades/hues of color are easiest to distinguish for humans?

I'm trying to represent data graphically and am using a variation of hue/lightness to distinguish one data point from the next. I would like to use a color that would allow me to convey most ...
7
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3answers
994 views

What is the science behind the inaccurate perception of colors?

If I go into a green room (all walls are semitransparent and green) and spend some time - around 10+ min - in there, when I come out all my eyes see is white as pink. I see no (or very few other) ...
6
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1answer
2k views

Is it biologically possible for an adult's eye color to change?

Can it be that the adult eye can change color? Specifically my question is about a unilateral color change, such that the color of one eye remains constant, while the other changes color over time. ...
6
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1answer
4k views

What causes the colors we see in eyes?

Genetics aside, what are the biochemical reasons the different colours of human irises? Also, related, how does eye colour change, particularly in childhood? (example: my eyes used to be blue, ...
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2answers
192 views

What is the minimum eye?

What is the minimum eye which confers some evolutionary advantage? By minimum I mean anything less than this has no advantage whatsoever and therefore is not favored by natural selection. By eye, I ...
11
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1answer
164 views

Are there specific conditions that allow humans to see ultraviolet wavelengths

It is fairly common knowledge that the lens in its normal state absorbs ultraviolet (UV) radiation. An interesting notion has come up from time to time in my reading that suggests there are a small ...
9
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1answer
1k views

Why do dog's eyes glow green on a photo?

Taking my current profile picture as a prominent example: This photo has been taken with flash. As I gather, this is the same effect that makes a human's eyes glow red on photos, namely the ...
7
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2answers
313 views

What is the eye muscle status when you stare at distant view through a glass wall?

The book said when you look at object close to you, the eye muscles contract and vice versa. I wonder what will be the status of the eye muscles when I stare at distance view (such as a mountain) ...
6
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1answer
8k views

Why can cats interpret things on a monitor/tv, but dogs cannot?

E.g. you can see a lot of videos where cats are smashing some mouse or spider on an ipad, but I have never seen it with a dog. I have a dog myself and I know that he sometimes responds to the sounds ...
5
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2answers
175 views

How does the eye know whether to focus further out or nearer in order to bring a blurry object into focus?

If the eye sees an object, but the object is out of focus, the eye could be focusing too near or too far. How does the eye (or the brain) distinguish one situation from the other? How does it know ...
4
votes
1answer
47 views

How are the vitreous humour and aqueous humour of the eye, connected?

My question is regarding the biological nature of the separation between the vitreous humour and aqueous humour of the human (or mammal) eye. What connects the two in terms of the passive transport of ...
3
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1answer
1k views

Perception of artificial light - flickering

I noticed something strange a couple of years ago. I was walking down the street at night, when it struck me that the street lights were flickering. But, when I turned to take a direct look at the ...
1
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1answer
45 views

Is it safe to look indirectly at the Sun?

I.e., is exposure of sunlight onto the peripheral vision less damaging than exposure onto the fovea?
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1answer
524 views

Amber eye color in Neolithic Africa

Given what we know of the genetics of eye color and their historical distribution, is it possible or at least plausible for a person born in the Horn of Africa during the early Neolithic (ca. 9000 ...
1
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1answer
86 views

Are human eyes equally sensitive to AC, and DC lamps?

Definitely anecdotal. This friend is hypermetropic, and uses reading glasses. He doesn't have major issues facing car headlights, or using a torch (the one with a bulb - not a white LED). Yet place ...
0
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0answers
7 views

How do drugs (or other molecules) move between the vitreous humour and aqueous humour of the eye? [duplicate]

My question is regarding the biological nature of the separation between the vitreous humour and aqueous humour of the human (or mammal) eye. What connects the two in terms of the passive transport of ...