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.

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What negative effects can pinhole glasses have on the body?

While shopping in the local supermarket yesterday, I was surprised to find this display on one of the shelves. I also realize that I should have taken a pamphlet with me, as well as a picture of ...
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1answer
124 views

Is it a limitation of the eyes, or the brain, that we can't see a moving bullet?

Are the photoreceptors in our eyes not fast enough to register the fast moving bullet, or is the brain not powerful enough to make sense of something happening that fast?
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What causes the colors we see in eyes?

Genetics aside, what are the biochemical reasons the different colours of human irises? Also, related, how does eye colour change, particularly in childhood? (example: my eyes used to be blue, ...
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247 views

Difference between 'Orbit' and 'Globe' in eye anatomy?

What's the difference between 'Orbit' and 'Globe' in eye's anatomy. Do they refer to the same ? I encountered this in this text: ... ciliary ganglion, which is approximately 3 mm in size, and ...
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2answers
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How can fruit flies and mice share the same gene that says to build an eye if they evolved separately?

I saw a documentary where they inserted the gene of a mouse that basically is the starting "build an eye" command into a fruit fly, and a fruit fly eye grew. My question is, if eyes of different types ...
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What animal's lower eye lid moves to upper one when closing eyes?

I know cock's lower eye lids moves to meet the upper one when it closes its eye. What other animals does this? BTW, "cock-eyed" can mean upside down, I think.
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612 views

Why do I always close my eyes when someone takes a photo of me using a flash?

Everytime some tries to take a photo of me with a flash I manage to close my eyes (blink). It's not intentional and it's quite annoying. Why am I doing it?
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1answer
53 views

Does retinal detachment happen more frequently at night?

My understanding and experience is that during the night photoreceptors are less tightly coupled to the retinal pigment epithelium. Does this make it more likely for a retinal detachment to happen at ...
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76 views

Eye Brain Mapping

If our eyes are separated by some kind of full proof barrier/isolation, is it possible that our brain can picture/visualize two different pictures at a time? How the brain will function in this ...
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Are human eyes equally sensitive to AC, and DC lamps?

Definitely anecdotal. This friend is hypermetropic, and uses reading glasses. He doesn't have major issues facing car headlights, or using a torch (the one with a bulb - not a white LED). Yet place ...
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1answer
137 views

Why are trichromat cone cells unable to sense ultraviolet and infrared radiation?

I understand that cone cells vary in the color they sense, is this because of wavelength, frequency, something else, or a combination of the previous? I also understand that tetrachromats can see an ...
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Eye color genetics

I am trying to find a model to link the phenotype eye color to its genotypes. I know that there exists a simple model from Davenport, which explains {brown,blue} eyes. Further, there is an extended ...
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879 views

How does this illusion work?

I found this image on Google+ If you shake your head you can see a portrait of a person. Can anyone explain how the image is constructed in the brain?
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1answer
78 views

Is RGB diode lighting okay for the eyes?

Is a light source giving off light composed of red, green and blue lights harmful to the eyes? Does it lack any important qualities that other artificial light sources, such incandescent lamps or ...
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135 views

How long can you keep sheep eyes in formaldehyde before dissecting?

We're preparing for an experiment in our classroom and my teaching partner and I are at different points in the unit. I am concerned that the experiment will be less successful because of the ...
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3answers
131 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 ...
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1answer
703 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 ...
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1answer
682 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 ...
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61 views

Is the eyes' movement discrete?

When tired and it was dark, I noticed that if I focused on a dim light source and moved my eyes fairly rapidly sideways, the resulting images that lingered for a short while were not smoothly blurred ...
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128 views

Eyelids interconnected?

I've seen a patient who had a Vitrectomy (eye surgery) done on a single eye manifest massive swelling on both eyelids. That seems like having my left hand swell after punching a wall with my right ...
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169 views

What are the “stars” we see after a bump on the head?

Sorry if this might appear funny. When I close my eyes for a longer time, and suddenly open it, I see some twinkling white small circles, and when i concentrate on anyone of them it disappears, as ...
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250 views

Screen brightness for reading in dark room [closed]

While searching online I did not find any conclusive article on whether it is good or bad for one's eyesight to read on a computer screen in a dark room. Most mention that it will cause strain that ...
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1answer
265 views

Can visual acuity be improved?

Is it possible to completely cure myopia using natural methods (i.e. not with Lasik etc.)?. I have seen websites claiming that exercising the eyes will help improve eyesight. Is this true?
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Why do glial cells of the retina become more abundant the closer they are to the optic nerve?

I am doing a project on expression of GFAP in the zebrafish retina. GFAP is a marker for glial cells. I have found that the glial cells are more abundant the closer they are to the optic nerve at the ...
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269 views

Foveal ganglion cell density (Tay-Sachs Disease)

I’m currently reading on Tay-Sachs disease and have stumbled upon something regarding the typical “cherry red” macula symptom. On the one hand it is mentioned that the macula is almost devoid of ...
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439 views

When did vision evolve for the first time?

Today I wondered what the first organism to evolve vision would have been. I assume that it would have been kind of primitive and basic, but of course extremely innovative and eventually useful to a ...
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1answer
363 views

Why do rod cells not recover after bleaching upon exposure to bright light?

I'm confused as to why, when exposed to bright light, rod cells cease to function. I understand that exposure to bright light bleaches all of the rhodopsin, but...so what? Why doesn't the bleached ...
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1answer
351 views

Why does this illusion work?

This is another image I found on Google+ All lines are absolutely straight, parallel and perpendicular but why does it appear to have a curvature? Related: How does this illusion work?
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How do optical illusions work? [closed]

Hello fellow investigators I have two questions about optical illusions 1) A photo mosaic is something like this http://i.stack.imgur.com/Pzplp.png What are the optical principles behind our eye ...
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1answer
87 views

Are rods/cones rejuvenated periodically?

Pretty much what the title states. Some cells/structures in the human body undergo rejuvenation periodically by flushing away older cells and growth of new ones. E.g Skin, Blood Does this (for want ...
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1answer
206 views

Cause of short sightedness/ far sightedness

I recently had gone for an eye test. The doctor told that short sightedness/ far sightedness is caused due to shrinking or expanding of the eye. One thing i forgot o ask him was what causes that ...
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1answer
496 views

How does laser surgery correct accommodation problems?

When someone undergoes laser surgery to improve eyesight, how does it correct accommodation problems? Why does it not help presbyopia?
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573 views

Is it true that newborn babies don't produce tears while crying? Why?

Well, I was just going through an article on eye, where in fun facts it was mentioned that newly born (for initial 1 to 3 months) babies do not produce tear while crying. Actually, I have found this ...
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1answer
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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 ...
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693 views

Do eye muscles relax when you close your eyes?

I wonder whether the eyes muscle relax when you close them. Common knowledge told us the eyes muscle get tense when you stare at nearby object. If you close your eyes, you eye lids have 0 distance ...