Questions tagged [human-eye]

Questions about the biological function and structure of the human eye.

41 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
6
votes
0answers
230 views

Could being exposed to excess UV in the arctic lead to a human eye color change? If so, what is the mechanism?

The CBS News article Expedition Antarctica: A father and son's journey to save the planet says (in part): Thirty-two years ago, Robert Swan made history as the first person to walk to both poles. ...
3
votes
0answers
100 views

Can low melatonin levels and/or LED lights cause or exacerbate macular degeneration?

I have two questions that may or may not be interconnected. My first question is: Does melatonin prevent macular degeneration? Could low melatonin levels (caused by blue-rich light exposure in the ...
3
votes
0answers
577 views

What is the average volume of the human Psychic tear? (“emotional tear”)

My goal is to find out the volume of the average human "emotional tear" (Psychic tear - sadness, happiness), specifically when crying. I found a lot of information about Basal tears (constant ...
3
votes
0answers
56 views

Infrared emitting diode eye safety

I'm thinking of creating my own laser tag system and am a bit concerned about the eye safety aspect. Most of the homebrew system I've seen use the TSAL 6100 diode(http://www.vishay.com/docs/81009/...
2
votes
0answers
37 views

Eye Optics/Emmert's law: Where to place scaled copies of an object so they have identical images on the retina?

I read that the center of projection of the human eye is the entrance pupil. So given a light ray which intersects the objects position and the center of the aperture stop, all copies of said object ...
2
votes
0answers
29 views

How would our vision be improved if our photoreceptors were not backwards?

I'm curious to how much better human eyesight would be if the nerves from our rods and cones were correctly placed behind the receptors? Are there any Animal Models with correctly placed ...
2
votes
0answers
21 views

Why does Cyan appear bluish rather than greenish, when the phototopic eye sensitivity is highest in green (and Cyan contains blue and green equally)?

Cyan contains blue and green equally. Phototopic eye sensitivity is highest in green. Why, then, does Cyan appear bluish to most of us, rather than greenish?
2
votes
0answers
50 views

How does sleep prevent our eyes from drying out?

If we don't sleep for about 16 hours, our eyes start to get dry, and no amount of eye drops helps. You use eye drops and then you're dry 10 minutes later. However, after you've slept for 8 hours, your ...
2
votes
0answers
58 views

Does the human eye see things at twice the distance in a mirror?

If I'm standing 3ft away from a mirror and looking at something in it that is behind me but 5ft away from the mirror, do my eyes see that object as 3ft? Or 8?
2
votes
0answers
49 views

How is the eye damaged by computer screens?

Eyes are damaged by persistent use of computer screens. On giving it some thought, it felt quite magical that your eyes are damaged simply by looking at something. I googled where there were articles ...
2
votes
0answers
63 views

Are there people who can change one of their eyes' depth of focus, while not changing the other eye's?

Are there people who can change one of their eyes' depth of focus, while not changing the other eye's depth of focus, without any surgical or other external mechanical intervention? Edit: let's ...
2
votes
0answers
954 views

Do blurry images cause eye strain? At what point is an image so blurry the eye stops trying to focus it?

I'm a user experience designer concerned about a new trend of blurring screens when showing a lightbox/dialog box over top (see below). From what I know, blurry images cause the brain to work hard ...
2
votes
0answers
44 views

Controlling the pursuit path of the human eye

The human eye scans images by panning focus along a certain path. Stork et al. (2002) revealed that there is a feedback process involved in moving ocular focus along a path that produces minimum ...
2
votes
0answers
43 views

How quickly can lasers of various wavelengths and powers impair human vision or cause pain in the eyes?

There is a discussion on HackerNews about how self-driving cars might be susceptible to confusion attacks using a cheap laser pointer and a RaspberryPi. Some people argue that human drivers, too, are ...
2
votes
0answers
683 views

Reason for different color perception in left/right eyes?

What could be the reason for a difference in color perception between the two eyes of an adult individual without any known eye conditions? In particular, a difference in the perceived color ...
2
votes
0answers
899 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 I'...
2
votes
0answers
1k views

What does salt do to styes?

Styes formed in the eyes are cured by dabbing at them with lukewarm water(I saw this being done many a times as a home remedy.) At times, common salt is added to the water before dabbing. My mother ...
1
vote
1answer
36 views

Inheritance of FEVR (Genetic Disease)

If a woman has FEVR and is affected by the disease, what are the chances of her passing the disease to future generations. I read somewhere from a credible source like NIH(I couldn't find the link ...
1
vote
0answers
67 views

Why do we get tunnel vision during fight or flight response?

I have a question regarding tunnel vision during the fight or flight response. I believe that during fight or flight high levels of adrenaline are released which causes the pupils to dilate allowing ...
1
vote
0answers
15 views

Can the eye determine which type of defocus is presented to it?

I have a question regarding myopic and hyperopic defocus. My question is, is the eye able to determine which type of defocus is presented to it and if so what mechanisms allow it to distinguish ...
1
vote
0answers
147 views

Is it possible to simulate tetrachromatic vision in a trichromat?

Suppose we are able to stimulate the whole matrix of cones of a human retina, targeting each cone individually¹. Normally we would project an image in the LMS color space onto the cones, in such a way ...
1
vote
0answers
23 views

What is the average eye sight for humans? How bad is one's eyesight if you are1 or 2 SD below average?

What is the average eye sight for humans? How bad is one's eyesight if you are 1, 2 or 3 SD below average? I googled but it was hard to find good search terms.
1
vote
0answers
27 views

Does the ratio between M and L cone cells vary in one indiviual?

Wikipedia says: The ratio of M and L cones varies greatly among different people with regular vision (e.g. values of 75.8% L with 20.0% M versus 50.6% L with 44.2% M in two male subjects). This ...
1
vote
0answers
69 views

If longer wavelength color is perceived faster by human, what about non-spectral color (black)?

Related to human vision, I read the hypothesis about how longer-wavelength color is perceived faster by human eye than shorter-wavelength color source : A Brief Classification of Colour Illusions. But ...
1
vote
0answers
77 views

Differences that are too small to see

Consider two identical pieces of paper. Scenario 1: On both something is drawn in black ink. If the difference between the areas covered in black ink is sufficiently small, I cannot see the ...
1
vote
0answers
272 views

Why bipolar neurons in retina transfer information via graded potentials?

Why should bipolar cells prefer graded potentials to action potentials? My attempt: I know that graded potentials are better in processing information since stimulus is directly proportional to ...
1
vote
0answers
443 views

Can human perception differentiate between monochromatic and polychromatic light?

Maybe monochromatic is not the right word, what I mean is light consisting of a single wavelength (i.e. a spectral color) versus light composed of photons of multiple wavelengths (intermediate color). ...
1
vote
0answers
653 views

Is the human eye supposed to see the lense effect?

Just as the GoPro cameras, we need lenses to be able to focus. Nevertheless, we can see the "fisheye effect" on the shots taken by GoPros. I am talking about this: Is it possible to notice the "fish ...
1
vote
0answers
86 views

Do squids or octopus suffer from myopia(hyperopia)? Do other vertebrates get myopia(hyperopia)?

Both vertebrates and cephalopods evolved very sophisticated camera-type eyes, and both are capable of focus. But it also pose a risk of inability of focusing, such as myopia in human. So is myopia a ...
1
vote
0answers
3k views

Why does vision gradually becomes dimmer in bright setting?

I don't know if this is only happens to me, but if I am in a well lit room and I stare at one point or just look at one area without moving my eyes around my vision in that specific light setting ...
1
vote
0answers
411 views

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

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 ...
1
vote
0answers
49 views

Does the change in eye color (melanin concentration) affect the iris pattern?

In cases of acquired heterochromia, is there a quantifiable change in the iris pattern; the clefts , furrows, etc. If yes, what changes are observed? And if no, are there any diseases or acquired ...
1
vote
0answers
417 views

Why are there ghost images of objects just out of focus

I have observed an interesting phenomena with my vision lately. I just think I have never reflected over this before but it might always have been this way. I am nearsighted and have no problem with ...
1
vote
0answers
185 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 ...
1
vote
0answers
122 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 ...
1
vote
0answers
104 views

Nystagmus drug FDA approval?

Congenital Nystagmus is an eye focusing disorder. It happens in manuals. Wikipedia lists several treatments on its page. Are any of those FDA approved for human use of that disease. drugs found to ...
0
votes
0answers
32 views

The position of the macula in comparison to the blind spot

Which is located in a higher postion? Macula or blind spot?
0
votes
0answers
244 views

Is there any biological basis for the commonplace “eyes popping out” cartoon?

We might all be familiar with images like these below: I see this clearly "works" in a cartoon context. It makes a point. That "eyeballs" hanging outside belong to the individual and can be shown ...
0
votes
0answers
6k views

Why do we see better on stretching our eyelids to the side?

I've often noticed that on stretching my eyes to the side I see a lot better. On searching, I read that this happens because the cornea reshapes itself (due to the ciliary muscles). But is that all, ...
-1
votes
0answers
46 views

Do certain animals really see more colors?

I've been perplexed by this for a while. If we look at a color wheel, all the colors transition smoothly into one another, and form a circle. There seems to be no space for "new" colors. We, ...
-1
votes
1answer
51 views

What causes eye strain when viewing any display?

Few everyday experiences: Staring at the physical paper (or any other sight in nature) doesn't cause eye strain. Staring at the LCD screen causes eye strain. Some of the differences in properties I ...