Questions tagged [eyes]

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.

Filter by
Sorted by
Tagged with
2
votes
1answer
39 views

Why does our visible range not include infrared or UV radiation? [duplicate]

As the radiation peak of the sun is in the UV region and since at around room temperature materials emit radiation at IR, I wonder why our eyes are not capable of using these wavelengths. I guess ...
1
vote
1answer
38 views

What happens to eyeball when you push your eye muscles harder?

I have myopia and I read that the rays of light intersect before the retina. When I can not see clearly I can push somehow my eye muscles and can see a bit clearly. The object gets clear but moves ...
1
vote
0answers
15 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?
1
vote
0answers
12 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 ...
0
votes
0answers
10 views

Functions of the layers that make up Bruch's Membrane

I have a question regarding Bruch's Membrane. Within Bruch's Membrane there are the following layers: Outer Basal Lamina Outer Collagenous Zone Elastic Zone Inner Collagenous Zone Inner Basal Lamina ...
0
votes
1answer
40 views

What is the very hard sphere inside the eye of many common fish made of and how is it called?

Inside the eye of many common fish, like tuna, scad, snapper, actually probably all fish I have eaten, is a small sphere made of some very tough substance. This sphere is even hard to crush with teeth,...
2
votes
0answers
17 views

Why do the eyes of this cat have different colours when viewed from different angles?

Why do the eyes of this cat have different colours when viewed from different angles? Both of the eyes of this cat appear yellow when looking straight at the camera. However, when the cat looks at ...
1
vote
1answer
49 views

What is the smallest visual unit perceptible to the human eye, like a pixel? (esp. in visual static)

If you close your eyes, you can often see visual static, where individual pixel-like things are much more visible than with the more smooth, crisp images one gets with open eyes. This led me to wonder ...
2
votes
0answers
47 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
2answers
3k views

Explanation of the ‘cherry red spot' in Tay Sachs disease

In Tay Sachs disease, a hallmark symptom is a cherry red spot in the macula of the eye surrounded by a halo of white. I understand that the ganglion cells, which are higher in numbers around the ...
0
votes
1answer
25 views

Does the human eye’s field of view shrink when focusing on far away objects?

It seems like the lenses of the eye is like a fisheye lens that flattens out to a normal lens when looking at far away objects. Does that also mean that the field of view gets narrowed down as well? ...
5
votes
1answer
97 views

Vitamin A Deficiency

I have a quick question regarding Vitamin A deficiency. The photoreceptor molecules in both rods and cones have the same general structure which is retinal which is bound to a protein called opsin ...
4
votes
1answer
40 views

Non-Salticidae with °oo° Eye Arrangements

Since childhood, I've always thought of the °oo° pattern of four frontmost eyes as iconic for spiders (note: the pattern does not account for any additional eyes or lack thereof further to the sides ...
8
votes
3answers
287 views

Do animals with their eyes ~180 degrees apart have depth perception?

Lots of animals have their eyes more on the side of their head, like an octopus or a parrot. Are animals with eyes more on the side able to tell the depth of objects at different distances? It seems ...
7
votes
1answer
940 views

Reason for seeing grid-like patterns when strobing a solid black-white image?

I was trying to do some stimulation for SSVEPs by strobing a solid black square and a solid white square. Weird thing was, I ended up seeing weird grid like patterns that looked like this, always of ...
3
votes
1answer
5k 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 ...
-1
votes
1answer
85 views

Is the backward positioning of photoreceptors bad design?

(Several questions have been asked about this topic but most are quite old and there has been at least one study since then that has attempted to answer this in a new way) Since photoreceptors are ...
2
votes
1answer
26 views

Does my nearsightedness come into play when creating light outlines in the distance?

After looking at a light and closing your eyes, you see an outline of the light. I was curious how my nearsightedness would come into play. I look at a light in the distance without my glasses on and ...
22
votes
3answers
47k views

Why do I see different hues of colors between each of my eyes?

Frequently, I see colors with a slightly different hue when looking through my eyes individually. The right eye is more red-tinted ('warmer' hued) and the left is typically more blue-tinted ('cooler' ...
1
vote
0answers
46 views

Why do some mammals have incomplete orbits?

I've noticed that a lot of carnivorous/omnivorous mammals (most, if not all the members of carnivora and some ancestral cetaceans), as well as some herbivores (marsupials), have incomplete orbits that ...
7
votes
2answers
13k views

Do octopuses have better eyes than humans?

I've read that unlike humans, octopuses have eyes "designed" the "right way", i.e. with the nerve fibers behind the retina, thus getting rid of the blind spot we humans have as well as theoretically ...
2
votes
1answer
833 views

What shape is the pupil of squirrels?

In the animal kingdom there is a striking variety of pupil shapes, with great variety among relatively close relatives. Cats have vertical slits. Siberian tigers have round pupils. Cuttlefish have a W ...
3
votes
1answer
128 views

(How) do horizontal pupils dialate?

I was looking at mongoose eyes in particular, but my understanding is: Circular (human-like) pupils simply get larger/smaller depending on light levels, no change in "shape" Vertical slit (cat-like) ...
5
votes
1answer
2k views

Can a color-blind person see color with filter glasses?

Why does color vision improve in color-blind persons using these filter glasses from Enchroma? Will a color blind person be able to see the same colors on a television? I'm asking, because the colors ...
0
votes
2answers
468 views

How far can a human see at night?

I am not talking about seeing in total darkness, which I understand is not possible. I am looking more about a question how far can a human see during starry night or with half moon/full moon. I tried ...
0
votes
0answers
19 views

What standard procedure taken to measure eye far point and near point?

I've read from various link that to measure power/dioptre of eye glasses lens, we need to put far point into equation for nearsightedness and near point for farsightedness. The problem is I cant ...
2
votes
2answers
692 views

Can the retina emit light?

The retina is light sensor, which converts light to an electrical signal. LEDs can both emit and receive light. Similarly, is it possible to apply electricity to retina to generate light? Simply put,...
0
votes
0answers
50 views

Difference in frame rates of normal and peripheral vision

I recently encountered an incident in my laboratory. It was evening and the sunlight entered the lab through a window with exhaust fans. So the ray kept flickering at fixed intervals. I noticed that ...
1
vote
1answer
53 views

Comparion between machine vision & human vision

I hope this is the correct Stackexchange to ask this question. I am trying to know : What is the current status of knowledge regarding human vision and pattern recognition. More specifically, How ...
1
vote
1answer
195 views

Can Green color give Rest to Eyes?

Is it correct that Green color gives rest to our eyes compare to other colors?
1
vote
0answers
586 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 ...
3
votes
1answer
61 views

How do cone cells underneath capillaries receive light?

Came across this image of retina's cross section: 1) How do the cone cells directly underneath the blood vessel ('demarcated in the picture') receive a spectrally correct representation of the ...
5
votes
2answers
11k views

Why do snakes not have eyelids?

Why is it that snakes do not have eyelids? Is it due to that fact that they are not as evolved as we humans and other organisms that have eye lids, or is there any other significance behind it if any?...
1
vote
1answer
84 views

What is violet color?

We have 3 color receptors in our eye, so assuming the above picture is precise we are checking for 3 wavelengths: 450nm, 540nm and 700nm. Pink for example has an RGB value of R (700nm): 1 G (540nm): ...
5
votes
4answers
798 views

Why do our eyes “wrap” hue from UV to IR?

On the high-wavelength side of things, we see almost-infrared as reddish, with a slight tinge of magenta. On the low side, we see violet fading into the same magenta color. Why is that? You can see ...
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
1answer
95 views

If one of eyes is blind, can that eye still feel pain?

I was wondering this when I touched my bare eye (my eye was open) and since I'm not blind I was wondering if an eye is blind, can it still feel pain?
8
votes
5answers
1k views

What is the smallest difference in light wavelength that the human eye can detect?

Is there a lower limit to the difference in wavelength (colour) our eyes can detect? If so, is this consistent between individuals? Are there any other traits correlated with precise colour vision?
1
vote
0answers
30 views

What happens to eyelids when we feel sleepy?

Why is that whenever we feel sleepy, our eyelids start to feel heavier. It is not like we can any time close our eyes and will immediately fall asleep. But, when we feel sleepy our eyelids ...
13
votes
1answer
12k 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
0answers
33 views

How many frames per second do human eyes see? [duplicate]

I observed when a helicopter rotor or fan is spinning the blades blur making it impossible to count the blades, but after a certain speed the blades seem to become visible making it possible to count ...
24
votes
2answers
2k views

Why does looking at bright light trigger sneezing in some people?

Why does looking at bright light trigger sneezing in some people? Are there any recent studies that have found a cause for this Photic sneeze reflex? The Wikipedia article only references studies ...
33
votes
1answer
11k views

How long do your eyes need to adapt to darkness and reach full contrast?

I heard you should wait some time until your eyes adapt to darkness and are able to see smallest luminosity differences, otherwise you might overlook faint objects in the ocular. Are there any rules ...
1
vote
0answers
22 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.
0
votes
0answers
30 views

Does cataract condition cause red film when sun is shining?

Since two years ago I have a red film in my field of vision when the sunlight (or a white spot) is at the border (or even lightly behind) of the vision field, the red color is especially obvious at ...
9
votes
1answer
6k views

Why does my eyes see a red spot when over exposed to light?

When I looked into my projector when it was on the blue screen it left a red spot in my vision. I should not have tried it but all the colors left a red spot. Why not a blue or yellow spot was left?
1
vote
0answers
447 views

What might alien have large eyes? [closed]

Don't rush to conclusions. This is a serious question. The most widespread depiction of intelligent, "human-like" aliens are that of a species with considerably larger eyes in proportion to body ...
4
votes
1answer
2k 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 ...
1
vote
0answers
365 views

Would a transparent iris serve its purpose?

The function of the iris is to regulate the aperture of the pupil. How does the iris obstruct light? Is it due to the pigment present in it? Or is it just due to the sheer presence of it? I am doing ...
1
vote
0answers
38 views

Why green light is good for our health? [closed]

I have a knowledge that when you woke up and see green light it increases your sight power. How it does so?

1
2 3 4 5 6