What is Eyes: Definition and 127 Discussions

Eyes are organs of the visual system. They provide animals with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and convert it into electro-chemical impulses in neurons. In higher organisms, the eye is a complex optical system which collects light from the surrounding environment, regulates its intensity through a diaphragm, focuses it through an adjustable assembly of lenses to form an image, converts this image into a set of electrical signals, and transmits these signals to the brain through complex neural pathways that connect the eye via the optic nerve to the visual cortex and other areas of the brain. Eyes with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system. Image-resolving eyes are present in molluscs, chordates and arthropods.The most simple eyes, pit eyes, are eye-spots which may be set into a pit to reduce the angles of light that enters and affects the eye-spot, to allow the organism to deduce the angle of incoming light. From more complex eyes, retinal photosensitive ganglion cells send signals along the retinohypothalamic tract to the suprachiasmatic nuclei to effect circadian adjustment and to the pretectal area to control the pupillary light reflex.

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  1. S

    Are cones in eyes sized to the light's wavelengths they perceive?

    Each of the 3 primary colors have a different wavelength so I'm wondering if that means each type of cone has a different size than another type.
  2. jedishrfu

    The Eyes of Trees are Watching

  3. BillTre

    Exploring Insect Vision: Muscles Behind Compound Eyes

    Here's something different: I just heard a podcast about recent biological research. Fly are insects (arhtropods) with an exoskeleton. An exoskeleton cuticle covers are the exposed surface areas of their equivalent of skin cells. The cuticle is usually stiff and hard (to resist mechanical...
  4. Astronuc

    BBC - Our eyes can change colour in surprising ways

    Our eye colour doesn't always remain constant throughout our lives – in fact, a wide range of external influences can change it, from injury to infection and sun damage. And sometimes the change appears to happen spontaneously...
  5. flying_bear

    Medical doctor, ophthalmologist, industrial PhD, chief medical officer

    https://www.linkedin.com/in/hellandhansen/ CMO at an ophthalmological tech company; Bulbitech. Now initiated an industrial PhD at the University of Oslo, supported by a Norwegian Research Council grant, where I will work on one of our tests (retinal adaptation speed to different lighting...
  6. DaveC426913

    B Scope Eyepiece diameter for old eyes

    I have a friend who wants to replace his scope. Has a balcony overlooking the lake, so less about stars; more about Moon and terrestrial. So he's interested in a (right side up) refractor. He can save on the mount by getting an alt-az instead of an eq. He's looking at this 4" Celestron...
  7. gehrenfeld

    B Exploring Infrared Light: Is It Visible to Our Eyes?

    I am 74yo and love Physics. If my basic knowledge of physics is correct, light is a photon. My question is: 1. Is the reason we cannot see infrared light because the spectrum travels at a wave link our eyes cannot see? 2. Does the light from the sun have all the different waves combined, and we...
  8. frost_zero

    The Science Behind Your Eyes: How Rods & Cones Work

    How do the rods and cones in your eyes work? I looked it up but didn't find any detailed explanation, and could we make them artificially to use like cameras?
  9. O

    Rhodopsin Phosphorylation Activation

    While glancing through an ophthalmology textbook several years ago, I learned that the transition between the two forms of rhodopsin (that results in neural activation and, ultimately, vision) can be accomplished through the electromagnetic energy provided by certain radio wave frequencies (and...
  10. jk22

    Medical Color of eyes : mutation due to evolution or racial selection?

    If different eyes appeared let say to less sun or an accidental mutation, has it become subject to selection of individuals like eugenism or due to modern gene technology nowadays ?
  11. K

    Is reflected sunlight damaging to the eyes?

    Is reflected sunlight on any surface otherwise than mirror or mirror-like surface safe for human eye? I can imagine mirror surface could reflect a lot of sunlight directly, making little difference from staring at the sun directly How about reflected sunlight on white but obaque surface? Could...
  12. J

    Artificial eyes and optic nerves

    There are millions of Glaucoma patients who lost or about to lose the sight to Glaucoma or just generally the blind which numbers in millions too. I know a person who has Glaucoma. I just want to know what is the status with artificial eyes and growing optic nerves at present and forthcoming...
  13. L

    A Through the eyes of a being that can see two in dimensions

    Since a phone is an object which can show three dimensions on a two dimensional screen, I wondered what a two dimensional being would see when they look at a smart phone or any other screen. So:What would a two dimensional being see, when they look at a smartphone?
  14. S

    History History or hoax? "D-Day Through German Eyes"

    There is at least one article online disputing the historical veracity of the popular book "D-Day Through German Eyes" https://www.dailymail.co.uk/news/article-7017619/Amazons-D-Day-bestseller-HOAX-Historians-claim-German-Eyes-book-fabrication.html (Of course, the Daily Mail might perpetuate...
  15. Auto-Didact

    I Human eyes can detect single photons?

    I'm not sure where this thread belongs; it is essentially a topic at the intersection between quantum optics, human physiology and even psychology, but I will focus more or less on the implications for quantum physics, so I just opted for this subforum. There is a recent article over Scientific...
  16. Akshaya dhakal

    Can we see radio waves or other invisible waves with our eyes?

    There are many electromagnetic waves. Some of them are visible while other are invisible. Can we see those invisible electromagnetic waves? How Please give with scientific reason.
  17. dangerboyy

    Could I get a second pair of eyes on this?

    1. Link to problem and the answer I got - https://ibb.co/ncGfDA 2. I got an answer, but I was wondering if this is correct or not? Am I correct to say (in part c) that the vertical component of the hinge's force will be equal to the sum of the vertical forces being exerted in the negative...
  18. jedishrfu

    Can Consumer Genomics Help Uncover Hidden Health Risks in Huskies?

    An article showing the benefits of massive consumer genomics: https://m.phys.org/news/2018-10-huskies-blue-eyes.html
  19. José Ricardo

    B Human Eyes vs Cameras: Exploring the Limits of Perception

    When the camera can oversee the human eyes?
  20. mishima

    Stargazing Protecting Optics (not eyes) During Solar Observing

    Hi, I don't have much experience with amateur astronomy, but I was going to try and take a few shots with my Canon EOS 20d mounted on my 6" Ritchey-Chretien astrograph this Monday. The telescope was manufactured by Orion, and was a few hundred dollars so probably not the highest quality. Since...
  21. A

    Mirror phenomenon — Concentric halos around eyes in a foggy bathroom

    Follow up a former thread, about concentric halo`s around the eyes, in a foggy bathroom mirror. I made an example picture of what was observed. But i don't know what causes the phenomena
  22. E

    Difference in hues between eyes

    Recently I have become curious of a difference between then colors I see with my left and right eye. After reading a bit about people with a similar experience I have found a pattern, almost every story I have read it seems that the right eye sees deeper colors such as red better and the left...
  23. Tareq Naushad

    Medical Why we think better with closed eyes? What about a blind person?

    To think something with full concentration I close my eyes. I believe many people also do it. It seemed to work and generates good thoughtful results. May be because with eyes closed brain is free to handle the billions of photons coming from eyes. In a noise-free room concentration should be...
  24. Tareq Naushad

    Medical With eyes closed or in a dream do we see video-like movements?

    We see real movements, we see videos, we see still photos. When we close our eyes and try to visualize some events like my son is running or sea wave or storm etc. do we visualize the movements or images with a very low frame per second(fps). In dream also we see so many events but are those...
  25. NaukowiecGirl

    Why do eyes only see in straight lines? (Light Physics)

    Hello! Please help me with this question. I'm currently studying Light and Geometric Optics and have become quite confused. When looking at diagrams of mirrors, and light relfection into eyes, why is it that eyes only see things when tracing the light in straight lines? For example, if an...
  26. O

    Are eyes the only input to animal vision?

    We already know about echolocation, using the ears to sense objects and space around us (also dolphins, bats, whales and some birds are quite good at this).. But how about using a sensor on our tongue to input visual information. Here is a Scientific American article describing this technology...
  27. DaTario

    "Unexpected" Image Formation with the help of our eyes

    Hi All, It is quite familiar the result bellow concerning the image of an object when it is on the focal point of a concave mirror (ref: http://www.physicsclassroom.com/Class/refln/u13l3e.cfm): "When the object is located at the focal point, no image is formed. (...) light rays from the same...
  28. C

    What would we percieve ions as in our eyes?

    I'm in high school and a physics novice. I have been wondering what would an object constructed of ions look like if we could see them? Is this a dumb question and there is a obvious answer I'm not thinking up for some reason?
  29. at94official

    Direction of Light to our Eyes

    Hi everyone! I just wonder when I use a laser pointer to other direction. How come our eyes able to see it? Since the light is traveling towards the other direction and not to our eyes. Is there an equation associated with that or its just basic logic is needed to understand why this happen. Skyte
  30. T

    Can you see the atmosphere with you eyes or only through photos? (In space)

    Among my favorite space photos are those in which you can see the Earth's, or other planets atmosphere, and I've always wondered if this was something like you can't see a galaxy with the naked eye, unless you use really long exposure times in your photos?
  31. Emmanuel_Euler

    Which Causes More Eye Damage: Acid or Base?

    What causes more damage to the eye? acid or base or both of them?? and why??
  32. E

    BBC Jim Al-Khalili Presentation -- robin bird eyes use quantum entanglement?

    http://www.bbc.co.uk/programmes/b04v85cj I searched in this forum and no one has mentioned this. What are the thoughts of general physicists regarding Al-khalili presentation how the robin bird eyes use quantum entanglement? Searching at the net producing the following...
  33. Ganesh Ujwal

    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 other words, it is better to read from a closer monitor with bigger font or from a further...
  34. Greg Bernhardt

    Software to soothe your computer eyes

    I rarely promote software, but since reading about the blue light glasses in the medical forum and remembering many members having trouble with light background sites I though I'd mention f.lux f.lux has pretty much extended the lifetime of my eyes. It follows the sun in your area to match your...
  35. Jesse Millwood

    Request For a Set of Eyes on an Oscillating Steel Cantilever

    Hello, I am an electrical engineering student and I was hoping some body here could help me out with a cantilever question. I want to model a vibrating cantilever with a mass at the end. I am doing this for a project where I wanted to model a Wurlitzer 200 Electric Piano. The way they produce...
  36. kyphysics

    Can Our Eyes See Objects in the Nanoscale?

    If so, what are some examples? If not, what is the smallest thing our eyes can see?
  37. J

    Speed of light that hits our eyes

    It is a postulate of SR that the speed of light in an inertial frame is always c, no matter what inertial frame is in question. But clealry, as I've understood, the Earth is not an inertial system and our bodies cannot be considered to travel inertially. So my question is, what is the speed of...
  38. P

    How to Determine Focal Length and Power of Lenses for Farsightedness

    Homework Statement A farsighted woman cannot see objects clearly that are closer to her eye than 60.0 cm. Determine the focal length and power of the spectacle lenses that will enable her to read a book at a distance of 25.0 cm. Homework Equations The equation I have been using to find...
  39. Monique

    What 80s Song Features the Lyrics Close Your Eyes and Moon and Stars?

    Name that song "close your eyes" I'd like to know the identity of a song, it's from the 80's or before and has slow lyrics. Unfortunately the only sentences I know are: "close your eyes" "moon and stars". The two sentences are right after each other and are sung really slowly (I guess sadly)...
  40. M

    Rubbing your eyes and seeing patterns

    I didn't really know what section to put this in but can someone expain to me what this is I experience? Basically I rub my eyes for a little bit and then hold my hands on my eyes pressing ever so gently and after a few seconds I'll see the most insane patterns of shapes and colours. Depending...
  41. S

    Bird eyes - and how to model them

    OK so I am not sure if this should be on a physics forum, a maths forum or a biology forum. All I know is I am stuck. A little back ground: Researchers have modeled how various animals can see depending on their visual sensor cells, namely cones (colours vision) and rods (luminance)...
  42. MarkFL

    MHB Where is the minimum intensity point between two bright lights?

    Suppose two bright lights are separated by a distance $a$, with one light having intensity $I_1$ and the other having intensity $I_2$. I am situated between the lights, trapped in a narrow passageway, and the light is blinding me. (Sweating) Please find the point at which the light I receive is...
  43. M

    A question about Bionic eyes and the visual cortex.

    Something that I've long wondered about is about the implications within our brain and visual cognition of implanting bionic eyes that would process the entirety of the EM spectrum. What is the consensus of the scientific community regarding this hypothesis, would our visual cortex instantly...
  44. Andre

    Did the Neanderthaler have too large eyes?

    Pierce et al 2013 compare numerous skulls of the Neanderthal with modern man and note much larger 'visual systems' and ... In other words they think that the advantage of having more let's say 'brain power' for Homo sapiens versus having a better eye sight for the Neanderthals gave the...
  45. J

    Why are our eyes tuned to a specific band of the EM spectrum?

    I mean why is it that the eye evolved to detect "visible" light instead of, say, microwaves. What is it about the visible light spectrum?
  46. M

    Effect of ambient light on eyes when watching television

    One watched TV in ambient light to avoid strain on eyes. What role is ambient light playing and how can this be explained in terms of physics of photons which come from the TV and which come from ambient light.
  47. M

    Light decomposing when moving your eyes

    last night i was in a bar, and i noticed that when i moved my head fast from left to right and right to left, i could see the reflection of white light in the beer barrels decompose in three colors. why does that happen?
  48. C

    IPS vs E-link, what's best for eyes?

    Hi, I'm running into the problem of getting eyestrain while reading e-books on my iPad. I know it uses IPS technology and read that E-link is better for the eyes. What are your onions? And what alternative to a iPad would you suggest for reading for longer periods?
  49. A

    Can we see light if we move our eyes at speed of light?

    Hello, We know we can not see light.It is only the effect of light that we actually see . Is it because of the fact that our eyes can't move at a speed of light? or its just basically the nature of light that we can never see it..? If I move my eyeballs at 'c', would I be able to see...