Did you know that in 20AD a Roman named Seneca looked thru a globe of water in order to help him magnify the print in the ancient Roman Books?
Did you know that in 60 AD the Roman Emperor Nero wore eyeglasses with LENSES made of EMERALDS to view the gladiator games?
Did you know that in China (around 1430AD )judges used to darken their glasses for the purpose of concealing their eye expressions in court?
Did you know that in the late 1600’s they used to keep glasses on their noses by using silk ribbons tied to the rims of the glasses and then hung the ribbons over their ears….with weights on the end to help keep them in place?
Did you know that in the 1700’s wealthy American colonists would search through basketfuls of spectacles imported from Europe to find the ONE pair of glasses that had the right prescription in them? Did you know that they paid as much as $200 PER PAIR for their glasses…in the 1700’s ?!?!?
Do you know who invented the Bifocal Lens??
(The ABOVE link requires FLASH to operate properly – if you do NOT have FLASH on your computer, you can get it for FREE by clicking the link below)
Interactive timeline provided by www.eyedidntknowthat.info
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Everyone has a BLIND SPOT in their vision of each eye.
Take this FUN test to check it out for yourself !!
Look at graphic of the cross and the circle at the top of this post.
Sit at your computer with your nose pointing in between the cross and the black circle.
Cover your LEFT eye and stare at the cross with your RIGHT eye.
Now SLOWLY move towards the computer screen while still staring at the cross with your RIGHT eye.
At somewhere around 10-14 inches from the computer screen – the black circle will disappear and the area where the black circle was…will now be all white – this is your BLIND SPOT.
If you move closer to the screen or farther away – the circle will re-appear. At just the right distance – the circle will disappear.
Now try the OTHER eye…but this time cover your RIGHT eye and look at the CIRCLE with your LEFT eye…..move closer and you will see that the CROSS now disappears!!
Your eye has an inner lining which is made of a sheet of nerves. This sheet of nerves is responsible for your vision and what you see and it is called the RETINA. There is a “hole” in the sheet where the Optic Nerve enters the eye. This area is called the Optic Nerve Head.
Photoreceptors are cells in the retina that detect light and allow you to perceive “vision”. On the optic nerve head there are NO photoreceptors. Thus, there is no light or vision detected at this spot in the retina. This is your “Blind Spot”. Every eye has a blind spot….your blind spot in your right eye is slightly on your right and your blind spot in your left eye is slightly on your left.
Your brain automatically “fills in” the blind spot area for you…..
Now try it AGAIN with the above green and yellow graphic….but this time you will notice that when you move to just the right distance , the circle will disappear and your brain will fill in your blind spot WITH YELLOW when you are looking with your right eye (left eye covered)….and your brain will fill in your blind spot WITH GREEN when you are looking with your left eye (right eye covered)!! Your brain automatically matches the surrounding colors when it “fills in” visual information for you.
Your brain can even “fill in” missing information for you…..in the above graphic, you’ll notice that when you cover your left eye and look at the cross with your right eye – the brain will “fill in” your blind spot (the area where the circle is). You will see that your brain fills in the line for you. Keep looking at the cross – don’t look back at the circle – or you will will see the circle again.
Try it AGAIN with the above graphic while looking at the cross with your right eye (cover your left eye) – your brain will put a red circle where your blindspot is….it is “filling in” the “missing information” !!
Graphics from Serendip….check out their very informative website at http://serendip.brynmawr.edu/bb/blindspot1.html
Posted in Eye Test, Fun Eye Stuff
Tagged Blind Spot, Blind Spot Detection, Blind Spots, Brain, Disappearing, Eye, Eye Blind Spot, Eye Chart Test, Eye Doctor, Eye Exam Charts, Eye Examination, Eye Exams, Eye Exercises, Eye Spot, Eye Test, Eye Test Charts, Eye Testing, Finding Blind Spot, Human Blind Spot, Illusion, Light, Online Eye Test, Optic Nerve, Optic Nerve Head, Optometrist, Photoreceptors, Retina, Vision, Vision Blind Spot, Vision Exam, Vision Test, Visionary, Visionary Eye Care, Visionary Eyecare, Visual Information, Your Blind Spot
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