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
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
374 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?
4
votes
1answer
18k views

Near point and far point of myopic eye

Suppose a person wears the specs of power -6D, the far point for that person is 16cm. But the near point of normal eye is 25cm. So, is the near point of a person with myopia (having far point less ...
1
vote
0answers
31 views

Would preserving your Eyes from Light keep them healhty?

I read about why eyesight diminishes with age. I am aware of the fact that there are different causes that can affect the quality of image received by our eyes and that being vague would not lead to a ...
0
votes
1answer
38 views

how much can changing light enter the eye shap what you see? [closed]

Does it change the shape and how objects are seen or does it just stop you from seeing certain things?
6
votes
1answer
260 views

Question to the color scientists

I have a question. if you look at these two spectral diagrams (SPDs) from two different televisions that is calibrated to the same white point (D65) 6500K with a spectrometer. The problem is that ...
7
votes
1answer
10k views

Dark veil when getting up too fast

I was asking myself this weird question. When you get up or stand up too fast, sometimes, you see something like a dark veil, and you aren't able to see anything distinctly for 2 or 3 seconds, then ...
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 ...
3
votes
1answer
2k 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
2answers
17k 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. ...
5
votes
1answer
3k 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 ...
7
votes
1answer
815 views

Can one eye affect the other eye's low-light adaption?

This previous question addresses how long eyes need to adapt to darkness and reach full contrast. My question is how does one eye affect the "transition" and/or efficacy of this "night vision" of the ...
1
vote
1answer
38 views

Why did we evolve to be able to see this specific set of wavelengths only? [duplicate]

It is understandable that life didn't evolve the capability to sense all wavelengths of light, it simply didn't need it. My question is, why did it evolve the set of wavelengths it has, for example, ...
1
vote
1answer
2k 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 BCE)...
1
vote
1answer
81 views

Does night mode on iPhone really help?

Okay so I know that night mode is supposed to filter out blue light that is bad for the eyes, but is it really more helpful than annoying? At night I do use it when I’m on the phone but it doesn’t ...
1
vote
1answer
115 views

How do our eyes see an inverted image? [duplicate]

How exactly do our eyes see an inverted image of what we are looking at? Does it have something to do with the shape of our lens (i.e. convex)?
7
votes
3answers
11k views

Why can't we feel pain when the eye lid touches the eye ball?

When I press a finger on a closed eye lid it means the eye lid touches eye ball, then I didn't feel any pain. Now I open my eye lid, then I small touch(not press) the eye ball, it gives me pain, why ...
1
vote
1answer
58 views

What are reciprocal inhibitory synapses?

Quoting Kandel's Principles of Neural Science, 2013, Amacrine cells generally receive excitatory signals from bipolar cells at glutamatergic synapses. Some amacrine cells feed back directly to the ...
12
votes
5answers
22k views

Why can't ciliary muscles in the human eye relax like other muscles?

I had laser eye surgery a decade ago, but in recent years my eyesight has become significantly myopic. I consulted an ophthalmologist to see if this was eye strain because I work at computers a lot, ...
4
votes
1answer
23k views

Are there animals / mammals which only have one eye?

Do all animals (of a certain size and not thinking about worms) have the possibility to perceive depth? Do all mammals have at least two eyes? Are there mammals with more than two eyes?
8
votes
4answers
659 views

Is it technically possible to make someone see something when their eyes are closed?

I'm writing a little article and need any information about how human vision works and latest technologies and discoveries around. Actually its not a professional article. Its for a group of my ...
25
votes
7answers
7k views

Why can't we see in low light if staring long enough?

For me it seems reasonable that if I kept my gaze on a fixed point in a room with low light, a progressively brighter and better picture would appear before my eyes, just like a camera can see in the ...
9
votes
2answers
8k views

Does our eyeball increase in size as we grow?

Does the size of the eye increase as we develop from the stage the complete eye first forms to infancy and then to adulthood ?
2
votes
1answer
616 views

What are these tiny, almost transparent, dots in my vision? [duplicate]

Sometimes when I stare at a very bright thing such as the sky I see little dots. It's actually more of a circle with a little dot inside it. They are half-transparent and they move around a lot. When ...
1
vote
1answer
2k views

What is the direction of the processing of light by the (human) retina and how does it happen?

Quoting Textbook of Medical Physiology by Guyton and Hall, 2016, page 647, ...the functional components of the retina, which are arranged in layers from the outside to the inside as follows: (...
1
vote
1answer
185 views

How many ommatidia does a honeybee have?

European honeybees (Apis mellifera) have compound eyes made of tiny facets called ommatidia. The number of ommatidia is usually known in most model insects, but I cannot find reference for the ...
1
vote
1answer
168 views

At what minimum distance the direction at which eyes point becomes parallel?

This is very similar, but different than this question about focus, let me explain why it's not a duplicate at all.. That other question is about the distance of EACH individual eye FOCUS, this one is ...
1
vote
1answer
7k views

Why do eyes change colour after death?

Why exactly do eyes turn black when we die? (Or even change colour at all). The source of inspiration to this question is due to this video https://www.youtube.com/watch?v=6mNs_TcUyHc&t=627s (it's ...
1
vote
1answer
68 views

Family eye genetics [duplicate]

Both my parents have brown eyes. My older and younger siblings have brown eyes. I have green eyes. Is this genetically possible? Back in 1962, this was questionable and led to family problems, ...
15
votes
4answers
3k views

Do insects with compound eyes have depth perception?

Do insects with compound eyes have depth perception? They fly as if they do, but their eyes are so close together it seems like the image would be 2 dimensional.
2
votes
1answer
347 views

What photoreceptors are necessary to permit infrared vision?

Humans have red green and blue photoreceptors allowing them to sense colours in the spectrum of about 400-700nm. Certain proteins allow for the extending of wavelength range in the RGB receptors, this ...
3
votes
2answers
2k views

Do the eyes play any role in producing the visual experiences you have during dreaming?

Sometimes, you remember a vivid picture of a dream that you saw. What is the role of your eye in this experience? Please provide me with the answer that is as simple as possible since I am in Class 10(...
0
votes
1answer
71 views

Why do left and right eyes can require different power of lenses?

Both the eyes almost see the same things throughout our life. It is not like we use one eye more than other that it should become weaker. What causes requirement for different power of lenses for both ...
2
votes
2answers
1k views

Can someone who is color blind recover color vision by surgical means?

I am currently studying color blindness, and there is no medicine that can help it. Is it possible nonetheless for someone who is color blind to have their eyes restored to normal color vision by ...
3
votes
1answer
22k views

What is the minimal focal length of the human eye?

What is the minimum length to which the focal length of our eye can go, even when considering the blurred images too.
1
vote
1answer
143 views

Is it the theory of the 5 senses obsolete? [closed]

An enigmatic topic in traditional science was labelled as the mystery of the 5 senses, and how to best group senses by type. Is that theory now meaningless? Do Scientists still agree that that ...
3
votes
0answers
106 views

How do photoreceptors overcome the ambiguity of wavelength vs intensity to determine brightness? [duplicate]

I asked a similar question about the Principle of Univariance yesterday, but now I have another one. According to the Principle of Univariance, the input to a photoreceptor differs along two ...
0
votes
1answer
262 views

What is the neural coding of rod and cone cells?

In Rushton's paper on the Principle of Univariance, he states: Thus, though the rod input has two variables, wave-length and energy, the output differs only in one respect, namely 'brightness'. ...
2
votes
1answer
106 views

Why do floaters in the human eye appear to have a squiggly-line, tubular shape?

If you intentionally try not to tune out visual floaters in the eye, you can see them very clearly and they seem to have a squiggly line shape but with a volumous tubular look. Why is this? They ...
2
votes
0answers
886 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 ...
10
votes
2answers
46k views

Is it safe to look at infrared LEDs?

What happens if one looks directly at infrared LEDs? Sometimes I see this kind of LED at night as red dots and I'm also courious about it. I was wondering what would happen if one looks directly to ...
1
vote
0answers
28 views

Does iris color effect the amount of light that reaches photosensitive ganglion cells?

Does eye color (of iris) have any effect on the amount of light reaching retina cells and hence effect melatonin production?
1
vote
0answers
1k views

What is the field of view of humans (not just fixed angle eyes)?

What is the human field of view also counting the maximum vertical and horizontal eye movement (rotation), with the head still. It is unclear from this question whether the answer relates to the ...
6
votes
3answers
25k views

Why do our eyes close when we sleep?

Why do our eyes close when we sleep? Is it to relax our eye muscles? How can it be explained from an evolutionary point of view?
7
votes
1answer
601 views

How are cells of the cornea transparent?

We know that cells have mitochondria, chromosomes and other organelles so that's why they are opaque but can you say how the cells present in the eye cornea are transparent and allow light to pass ...
2
votes
0answers
2k views

Does Rüppell's Griffon Vulture Have Greatest Vision Acuity? (Small Carrion Spotted at 10 km+?)

Synopsis: Some sources seem to imply the Rüppell's (griffon) vulture (Gyps rueppelli) can see objects at a distance in excess of 10 km -- roughly three times the ...
2
votes
1answer
140 views

How can Giant squid have $20,000 mm^{-2}$ photoreceptor cells, but no cones?

According to this post, Cephalopods have about $20,000 mm^{-2}$ photoreceptors in there eyes. However, Cephalopods (in my case, the Giant Squid) aren't born with cones (cells that dictate which ...
0
votes
1answer
57 views

Myopia & the Blur Effect

I know myopia is caused by elongation of the eyeball. When the eye is too long, light entering the eye balls falls in front of the retina instead of on it. However I do not quite understand how this ...
3
votes
2answers
1k views

Could there be any effects from low powered infrared being used to track eye movements long term?

Basically, looking into infrared LED's and a camera with an infrared bandpass filter for tracking eye movements; my concerns are whether there would be any potential negative long term effects from ...