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Showing posts with label eyesight. Show all posts
Showing posts with label eyesight. Show all posts

Thursday, 11 April 2013

How visual illusions work and how they trick our brain and eyesight


"Most believe that Visual illusions is only something you can have fun with. it is a misconception, ''

"It is important to conduct research into illusions, because they show us how our visual system works. They tell so to speak, what are the basic rules that apply to our Visual apparatus. "

By way of example,  Ramachandran illusion number. 4, where we are forced to react to the shadow. The brain, which is used to light from above in the form of sunlight, assumes that the object is illuminated from above. Turn the drawing 45 degrees-the brain maintains that the objects illuminated from above and therefore creates an entirely new conception of the image.

Illusion 2 shows how the brain is coded to construct an outline based on incomplete data. A useful ability, says Ramachandran, for example this helped our ancestors be able to spot a tiger who sneaks around in some high grass.



Fill in the blind spot
Close the right eye, focus on + sign, and then drag slowly the drawing toward yourself. The red dot will disappear when the focused image in the left retina cover the place where the optic nerve enters out of eyeball-called the blind spot, because it has no photo receptors. But using data from nearby receptors the brain can improvise and fill in the blind spot with oblique lines similar to those that are just around the icing.



Illusory triangles
The white triangle (left) appears to lie on top of the triangle, which is bounded by the blue lines. But if you look long enough, the pages of the white triangle disappears. This is due to the fact that its brightness coincides with the surrounding white color. The illusion works for most, if not blue and Red will appear with straight strong brightness-possibly because the brain cells that can distinguish outlines, might be color blind.







After Pictures
Look at the + sign in the colored circle for 1 minute, and then move your gaze over to the colourless diamond. You will now be able to see areas with colors that complement the original shades. Clockwise from top right, red, blue, yellow and green replacing the original colors. Possible explanation: When neurons, which are susceptible to one color, become exhausted, opposing neurons produce complementary colour.



Shadow provides outline
Since we live in a solbelyst world, we assume that all light coming from above, and therefore we use the shadows to determine the outline and shape. This pattern becomes an X of concave circles when you rotate it 90 degrees to the left. However, if you turn it to the right, it becomes an X of convex circles.




Is there one line?
you may need to be convinced ... but the two featured lines in this corridor are actual equal length. Perspective cheating the brain to perceive the line that is "nearest to", as being shorter. Even though we know that that is what is happening, our Visual apparatus get's confused.





One or two shades of gray?
The color in the two small triangles are the same. They look different to most people, because the yellow and the blue color in the two large triangles affects visual perception. When the brain to pick up colors, it will take the big picture into account.





Faces or vase?
You see either two faces or a vase. But you can not see the faces and the vase at once, because our brain perceives a object by delineating it from its background. Here are both prospects are equally likely, so Visual perception switches back and forth between the two images.





Parallel or not?
The short lines that cross the long, confuses the brain cells, which stands for orienting the perception-and the through-lines are seen therefore as divergent. But that is not the case-try once to turn the drawing, then you see it from the lower left corner ... The long lines are actually parallel.





Where does the grey come from?
There, where the white lines intersect, you can see flashing grey spots. They are due to the way retinal cells respond to light in this geometric image. The contrast between black and white either accelerate or hinder these cell reaction and thus arises the illusion.


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Wednesday, 10 April 2013

What is night blindness?


Night blindness means that a person cannot properly orient there eye sight in the dark. The eye usually becomes accustomed to dark but with night blindness this doesn't happening the normal way.

One can be born with night blindness or have gotten eye disease retinitis pigmentosa, where the field of vision will become less and less eventually ending up with total blindness. More likely, it is a question of a lack of vitamin A,  flavonoids and carotenes that makes some see worse than others in the dark. These dietary factors are namely the chemical precursor and are needed for the eye's Visual purple, wich converts light to electrical impulses. They are sent to the brain's vision center, where they are registered as visual impressions and pictures.

When the light passes through the eye's pupil, the light goes  on the retina, which is made from the aforementioned dietary factors.

The eye has two kinds of sensory cells-rod and cone cells. The rods are the most sensitive, and we use them in the dark.

When a person cannot detect the weak night lights, is it due to a lack of Visual purple in the rods. It gives us night blindness.




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Saturday, 16 March 2013

Pinhole glasses how you can improve your eye sight


In my last post I explained the different parts of the eye now however i will be explaining how you can improve your eyesight using pinhole glasses. Pinhole glasses are now being used more than ever by people who are wanting to improve there eye sight.
As you get older your eye sight may get worse this is because this can be due to a number of different things a common cause could be the weakening of the muscles in your eyes that manages focus and makes you see clearer also exposure to UV light can over time damage your eyesight.

The problem of your muscles in your eye weakening however can be solved or even prevented. This is because you can wear pinhole glasses that will actually strengthen the muscles in your eyes by training your eyes for around 15 minutes a day by reading a book or watching TV whilst wearing the pinhole glasses you will find that you will not only strengthen and prevent your eye muscles weakening but also they will be stronger and you will in fact get better eyesight.

A added bonus to this as well is that your eye muscles will be faster to react as well to harmful sudden changes in brightness that could lead to the damaging of your eyes. Faster reaction times and the muscles making appropriate alterations to their shape will mean you will be better protected.



The cost of buying a pair of pinhole glasses is that much really and they can really make a difference to your eye sight if you make sure you keep on wearing them each day for only a little amount of time.

pinhole glasses are availbe to buy online here: buy a pair of pinhole glasses today!





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The different parts of the eye



Your eyes are very similar to the design of a camera with how they work.

This is interesting fact* 

When you look at an image the image that your eyes see is actually upside down and it is up to your brain to correct this and actually turn the image the correct way up"

To understand how your eyesight works let me explain a bit more about the different parts of the eye and what they actually do:



Cornea
The Cornea is a see through too let light pass through it and helps to protect your eyes.

Sclera
This is also a important part of your eye it is the white part of your eye... skin that covers the outside part of your eyeball and is quite tough.

Iris
You Iris (the colored bit) is crucial for managing the quantity of light that goes into your eye.

Pupil
The pupil of your eye is actually a hole that is located in the center of your iris. Pupil often changes size depending on the light conditions you are in.

The lens of the eye
The lens is used to focus light into the retina of your eye. the lens will often also change its size accordingly so that your eye sight is as clear as it can possibly be.

Retina
This is kind of where the the image is "displayed" to your brain. Because of how the light has entered onto the retina the image being displayed will be upside down. With rod and cone cells the retina uses these cells to convert the image into electrical messages for your brain to process.

Did you know that*

Rods cells are used to pick up and convert the black and white and the cones cells are used to pick up and then convert the colors of the image.

Blind spot
The blind spot that is found on your retina is a part of you eye that does not process or pick up any light it is instead a part of your eye where the retina is joined to the optic nerve.

Optic nerve
A crucial part of your eye this is where the electrical messages created by the retinas cone and rod cells will travel to your brain. 

Tear glands
It is important that the surface of your eye doesn't dry up so keeping it moist is needed to do this your eyes use tear glands on the side of your eyes to produce moisture for them.

Blinking will spread the moisture produced via the tear glands evenly over the surface of your eyeball.

Conjunctiva
Conjunctiva lines the inside and also the outside of your eye but the Conjunctiva is not found however on your Cornea as this would obstruct the light.

Aqueous humour
Is the liquid found in your eye and lens.

Vitreous humour
This is a crucial denser type of liquid that gives your eyeball its overall shape and structure.
This liquid makes up the largest proportion of your eyeball.

Eyelids and Eyelashes
Eyelids and Eyelashes are needed to keep light out when you are sleeping and to also constantly circulate the liquid produced from the tear glands around your eye. Also they help to keep dust out and protect your eyes.

Please see my newest post: improve your eye sight with pinhole glasses
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