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.

learn more… | top users | synonyms

-1
votes
0answers
11 views

Two colors in the eyes [on hold]

my husband has dark brown eyes and they turned blue in his seventies. The brown is back with a blue ring around it. Why is that?
1
vote
0answers
42 views

Can our eyes see faster? [on hold]

There are some animals that react faster than normal rate (like flies, etc). I guess it's because they can see faster than other animals and humans, as if time passes slower for them. I think some ...
2
votes
0answers
20 views

Can a stationary eye with a moving pupil exist? [closed]

I am making a sci-fi web-comic set on an alien world and I thought up an idea for an eye that works much like an eye from a mammal, but instead of moving the whole eye, only the pupil moves. This idea ...
0
votes
0answers
11 views

What is the permeability of proteins across the hyaloid membrane of vitreous to retina?

Does anyone know of any experimental work to test the permeability of the hyaloid membrane between the vitreous humour of the eye to the retina to proteins? Currently the largest molecule I can find ...
0
votes
1answer
32 views

What is the surface area of the vitreous humour in contact with aqueous humour?

This is a question regarding the anatomy of the human eye, however for my purposes medium sized mammals should do. I am interested in estimating the surface area of the hyaloid membrane of the ...
9
votes
1answer
111 views

Does your iris color have an effect on your vision?

I've always wondered if having different iris colors, (eye colors) may have any advantages or disadvantages on ones vision. Specifically regarding the effects of light. Personally, I have troubles ...
1
vote
0answers
42 views

Would a VR headset exacerbate myopia or could it be used to retrain the eyes?

I've learned that there are two primary hypotheses to explain myopia: not enough use of distance vision or not enough sunlight If the distance between an eye and what it's focusing on is the primary ...
0
votes
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 ...
4
votes
1answer
58 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 ...
5
votes
1answer
247 views

Why did Opabinia have 5 eyes?

I recently read about a fossil called Opabinia. What intrigues me is that it had five eyes. I was under the impression that most features, such as eyes, ears and legs are always even-numbered, i.e., ...
2
votes
2answers
65 views

Does “squinting” make you concentrate better on a logic test?

We have all had those moments of intense concentration on some tough exam, perhaps a college test or whatever... Why is it that when we squint, it feels like we can focus and concentrate better on ...
1
vote
0answers
43 views

Random small after-images of things not really there [closed]

I am 44 years old and have noticed that I often get small blotch afterimages that last for about 5-10 mins. Normally, everybody gets these when they look at a bright light. I seem to get these every ...
3
votes
1answer
43 views

How does tearing work?

I found the question about tear gas very interesting. Shigeta says there that crying helps the cells of the eye to wash themselves clear of the toxic components in the tear gas. Does non-emotional ...
0
votes
1answer
19 views

What happens in lasik operation?

First of all,I am very bad at biology. So please bear if it sounds elementary. I heard about lasik operation for reshaping cornea. Assume the patient is suffering from myopia implying lens is ...
0
votes
0answers
23 views

Undistorting peripheral vision

I am interested in a procedure which can be applied to an image (or video) which is situated in my peripheral vision, and will result in an undistorted copy being presented to my brain. I do not know ...
0
votes
1answer
74 views

Why does our eyes got wet when we feel emotional or whenever we are hurt? [duplicate]

I was thinking like whenever when we feel emotional or whenever we got hurt we got tears from our eyes but why is that happen ? Why our eyes got wet ?
12
votes
1answer
777 views

What portion of the electromagnetic spectrum do cats see?

I have seen numerous articles and various information about how cats and dogs see into the ultraviolet spectrum with interesting artistic renderings such as this: ...
4
votes
1answer
30 views

Wearing sunglasses during a solar eclipse [closed]

Note: I had asked this on Physics, but it is off-topic there due to being about safety. On the BBC's guide to eclipse-watching, Dr Lucie Green says: Watching an eclipse with normal sunglasses ...
1
vote
1answer
51 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?
0
votes
2answers
227 views

Why is my peripheral vision better for seeing in the dark? [duplicate]

I often walk around my house at night with the lights turned off and one night I noticed that looking straight at an object with very little light available made the object disappear from sight but if ...
11
votes
1answer
530 views

Why can I see a light flicker when it's in my peripheral vision?

When I'm looking at an old CRT monitor or a worn fluorescent lamp, but not directly in the center of my gaze, the light from it seems to flicker. When I focus my gaze onto the monitor or lamp, the ...
14
votes
2answers
1k views

How do birds deal with their eyes drying out at high speeds?

My eyes tear up when cycling at 15 mph, which is nothing compared to bird airspeeds. Do birds continuously produce lots of tears and blink a lot, or do the eyes self-moisturize from the inside ...
0
votes
0answers
52 views

Why does a human's field of view narrow when moving faster?

A relative of mine is a driving instructor and he regularly likes to bring up that the field of view narrows noticeably when driving at higher speeds. Is this true, why is this so and does this apply ...
1
vote
1answer
59 views

What is the minimum functional biological light sensor? [closed]

As a follow up to this question regarding the evolution of the eye, it was suggested that primitive eyes only needed to evolve a light sensor and could perhaps use the existing biochemical cascade ...
2
votes
2answers
193 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 ...
1
vote
1answer
159 views

Are the irises an exact match in a human's set of eyes?

Are the irises an exact match in a human's set of eyes? Assuming the eyes are healthy with 20/20 vision.
2
votes
0answers
59 views

Sensitivity of eyes to flashing lights

My eyes are very sensitive to flashing lights - for example I'm always the first person to notice that a fluorescent tube is about to fail because I see it flickering when other people can't. When ...
2
votes
0answers
121 views

White/Gold vs Blue/Black dress

So I'm sure you've all seen the dress photo where people see the dress as either White and Gold or Blue and Black. It has essentially 'split' the internet because some people see the dress and they ...
2
votes
1answer
154 views

How come all my family have brown eyes and I have blue eyes?

My whole family tree up to my grandparents have brown eyes, I have blue eyes, how come? I don't know if it matters but I have not received enough oxygen at birth, doctors said it's probably the ...
12
votes
3answers
3k views

Superhuman eyesight

My ten year old son was reading car number plates that were too fast, too far away and at the wrong angle for any of us to read or even believe that it was possible for him to read. We thought he was ...
7
votes
1answer
830 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 ...
1
vote
1answer
72 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 ...
5
votes
1answer
427 views

Why do we get 'bags under our eyes'?

Why do these circles form around the eyes if somebody is tired? And why does fatigue express itself around the eyes this way? Can I get eye bags very quickly in another way? ...
1
vote
0answers
91 views

Eye strain using 3D screens

I don't know if this is a physics or a biology question but this might be better orientated around the element of how the human eye works in a 3D visual situation than physics. Given the rise of 3D ...
9
votes
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
votes
3answers
995 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) ...
4
votes
1answer
483 views

Why are irises unique?

I heard that irises are different and unique for every person. According this link, probability of two irises having identical pattern is 1 in 10 to the 78th power. That's how iris scanners identify ...
3
votes
1answer
263 views

Why do small fonts strain the eyes?

I understand that too much close reading will strain the ciliary muscles of the eyes. But what about small fonts? The contraction of the ciliary muscles is dependent on the distance not font size. In ...
8
votes
1answer
458 views

How does the cornea breathe during sleep?

The cornea is not supplied with blood vessels and so exchanges gases directly with the atmosphere. So how does it breathe during sleep when our eyes are closed?
5
votes
2answers
193 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 ...
1
vote
1answer
24 views

Flicker fusion threshold for insect eyes

I searched on bio-numbers for flicker-fusion threshold of insect eyes in general and for flies in particular. Ruck, 1961 gives values for some flies. Is there any database maintained for these values? ...
5
votes
2answers
201 views

How do gory images lead to nausea?

How do gory images lead to nausea? Yesterday my friend visited shock sites (a website). He said that he got nauseous sensation within seconds after viewing the gory images. However, I don't ...
6
votes
1answer
3k 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. ...
1
vote
0answers
47 views

How to compare a camera and an eye

How could I compare what a normal eye can see to a camera lens? I just went through a very comprehensive article @ CambridgeInColor, but I'm still not really clear. When I take a picture with a SLR ...
11
votes
6answers
3k views

What is the use of eye banks, if eyeball transplants do not exist at present?

Corneas are donated and transplanted, but not the eyeball. I don't understand. What is the purpose of donating a cornea without an eyeball to a blind person?
1
vote
1answer
74 views

Does pupil size affect image focus in persons with no lens?

If an individual has no lens like Claude Monet (who had them removed). They should be able to still focus the images they see in a well light area if they shrink their pupils to a very small size ...
1
vote
1answer
24 views

Can we directly stimulate M cones in retina with current technology?

I wonder if we could try to see imaginary "supergreen" color by directly stimulating M cones. For this I suppose we'd need: Non-destructively scan specific human's retina to locate exact positions ...
2
votes
1answer
50 views

Like size and colour constancy, why does the brain not maintain focus constancy?

I have progressive myopia. I grew up with perfectly normal eyes but slowly started getting myopic. The thing is, my brain knows (or should know) what the world looks like -- it knows that far away ...
4
votes
1answer
174 views

How do animals handle light refraction in different media?

For a human, when diving underwater, everything is blurry because of the water's different refractive index compared to that of air, which we are accustomed to. How do animals, like turtles, seals or ...
0
votes
2answers
107 views

How come degraded eyesight still holds with a mirror? [closed]

When you use a mirror to look at something, you can position it at an angle arbitrary to your face and still look at an object far away. My question is, for degraded eyesight, how come the picture is ...