INTRODUCTION
Hi one and all. Welcome to our blog!!! Don’t you guys think that it is so pretty and nice? I bet you all do. Anyway, we believed you guys will have an interesting and enriching time when visiting our blog. By visiting our blog, you all will be able to know more about one of our sense organs --- the eye. Over here, we will give you a brief introduction about our wonderful eye and also at the same time let you guys know some interesting facts and viewpoints.
Our amazing sense organ—THE EYE

Have you guys ever wondered how does our eye work? Why can we see things? Well, if you continue reading, you will be able to find out why. Eyes are organs that detect light. Different kinds of light-sensitive organs are found in a variety of animals. In the human eye, light enters the pupil and is focused on the retina by the lens. Light-sensitive nerve cells called rods (for brightness) and cones (for color) react to the light. They interact with each other and send messages to the brain that indicate brightness, color, and contour.
When you look at an object, light rays are reflected from the object to the cornea, which is where the miracle begins. The cornea is a transparent structure found in the very front of the eye that helps to focus incoming light.
Behind the cornea is a colored ring-shaped membrane called the iris. The iris has an adjustable circular opening called the pupil, which can expand or contract depending on the amount of light entering the eye. A clear fluid called the aqueous humor fills the space between the cornea and the iris.

Situated behind the pupil is a colorless, transparent structure called the lens. The lens' job is to make sure the rays come to a sharp focus on the retina. The resulting image on the retina is upside-down. Here at the retina, the light rays are converted to electrical impulses which are then transmitted through the optic nerve, to the brain, where the image is translated and perceived in an upright position!
Ciliary muscles surround the lens. The muscles hold the lens in place but they also play an important role in vision. When the muscles relax, they pull on and flatten the lens, allowing the eye to see objects that are far away. To see closer objects clearly, the ciliary muscle must contract in order to thicken the lens. This is called accommodation.
The interior chamber of the eyeball is filled with a jelly-like tissue called the vitreous humor. After passing through the lens, light must travel through this humor before striking the sensitive layer of cells called the retina. The retina is the innermost of three tissue layers that make up the eye. The outermost layer, called the sclera, is what gives most of the eyeball its white color. The cornea is also a part of outer layer.
The middle layer between the retina and sclera is called the choroid. The choroid contains blood vessels that supply the retina with nutrients and oxygen and removes its waste products. It is pigmented black so as to prevent internal reflection of light.

Embedded in the retina are millions of light sensitive cells, which come in two main varieties: rods and cones. Rods are good for monochrome vision in poor light, while cones are used for color and for the detection of fine detail. Cones are packed into a part of the retina directly behind the retina called the fovea. When light strikes either the rods or the cones of the retina, it's converted into an electric signal that is relayed to the brain via the optic nerve. The brain then translates the electrical signals into the images we see.
Wow, don’t you think that’s amazing? Read up on our various blog posts to know more about the eye! (:
Myopia / Shortsightedness
Thursday, March 6, 2008/
11:41 PM

Light entering the eye is focused onto the retina. Most of the light (70%) entering the eye is focused by the cornea ,while the rest is focused by the lens, which is situated just behind the cornea. If the light is focused properly on the retina, we see a clear image. If the light focuses in front of the retina, the image is fuzzy.
For people who suffer from myopia, it is usually the case of the corneas of their eyes being too curved or the eyeball too elongated. Images are focused in front of the retina rather than directly on it, and therefore, what appears to them will be blur, unclear images. To a short-sighted person, distant objects seem blurred, while near objects can be seen more clearly. Other symptoms can include headache and tired eyes. Children may not even realise that they have blurred vision. Therefore, parents or teachers have to be extra observant and send the child for eye checkups if they squint or frown a lot, hold books close to their face, or have trouble seeing a blackboard, television or cinema screen, which are all symptoms of myopia or shortsightedness.
Myopia most commonly develops in childhood or early teens (between 8 and 14) as the growth of the eyeball is most avid during this period. It normally stops getting worse when we reach adulthood. The risk of developing myopia is increased if there is a family history of it. A link has also been proposed between myopia and prolonged close-up work, such as reading or sitting close to the television, although there is little scientific evidence to reinstate this. Myopia can be associated with certain types of cataracts, where the lens becomes cloudy. It can also be caused by a condition called keratoconus, in which the cornea thins and becomes more curved.
Most people have mild myopia and there are no serious problems. However, in some rare cases, the eyeball continues to grow and myopia becomes progressively worse. This is called pathological myopia. People with this type of myopia are at an increased risk of developing certain other eye problems, like retinal detachment, when the retinal lining separates from the back wall of the eye, which can sometimes lead to blindness. For example, a few people with severe myopia may get retinal detachment, which is when the retinal lining separates from the back wall of the eye. This requires urgent surgical treatment to prevent permanent loss of vision.
Myopia can usually be corrected with glasses or contact lenses. These work by refocusing the image on the retina. Glasses can be worn by people of all ages, and are less expensive than contact lenses. However, they may get in the way of some types of work, and they fog up in humid or cold weather. Contact lenses give better side vision than glasses, and come in a wide range to meet individual needs. However, contact lenses may need cleaning and disinfecting (if they are not disposable), and they require care in insertion and removal. Also, they can cause infection, dry eyes, and scratches of the cornea. Surgery can correct myopia by altering the shape of the cornea. The most common is LASIK (Laser in-situ keratomileusis) treatment. A small flap is made in the cornea, and a tiny piece of tissue is removed accurately with a laser. Vision may be hazy or blurry for a few days after surgery. The long-term safety and effectiveness of this procedure has not been proved. However, before taking the risk to undergo surgery, here are some side-effects that you might want to take note of: slight discomfort and watering eyes for a few hours, light sensitivity and possible dryness in the eyes for up to six months afterwards.
Complications are another factor to consider before going for surgery rashly. Most people are not affected, but the main possible complications can include:
clouding of the cornea
glare around bright lights
over-correction (long-sightedness) or under-correction (under-treated myopia)
infection of the cornea, which is usually treated with antibiotic eyedrops
increased pressure in the eye (glaucoma)
puncture of the cornea or eyeball
retinal detachment
Basically, we just have to take good care of our eyes by giving them appropriate rest and not over-straining them by reading under dim light or using the computer for long hours etc. This will certainly help in reducing risk of myopia. Just like our body, our eyes need adequate rest to be able to function well. Let us start from today to give our eyes 'a better, and healthier tomorrow'! :D
Credits: http://hcd2.bupa.co.uk/fact_sheets/html/myopia.html
rachel [4F/23] --*
short-sightedness!
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11:32 PM
Here's a short joke to lighten up all our stressed, hectic lives... enjoy! (:
A man went to see an ophthalmologist and complained that he was short-sighted.
The doctor took him outside, pointed upward and asked, "What do you see there?"
"The sun," the man replied.
The eye doctor asked, "How far do you want to see!?"
Haha! Isn't that REALLY FUNNY!!!! :DDD
rachel [4F/23] --*
Your Eye's "Megapixel" Resolution
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11:30 PM
We have always been using cameras and video cams to document images, but how about our eyes? Our eyes are one of the most amazing things in nature, as it that enables us to see. 8)
As a matter of fact, the typical human retina has an average of five million cone receptors on it, which are responsible for colour vision. There are also a hundred million rods that detect monochrome contrast, which plays an important role in the sharpness of the image you see.
The eye moves rapidly in small angular amounts and continually updates the image in one's brain to "paint" the detail. We also have two eyes, and our brains combine the signals to increase the resolution further. We will also naturally move our eyes around the scene to gather more information. Because of these factors, the eye and the brain assemble a higher resolution image than possible.
In good light, we can distinguish two fine lines if they are separated by at least 0.6 arc-minutes (0.01.Degrees). Blackwell (1046) derived the eye's resolution, which is 0.35 arc-minute (or smaller) at the limit of visual acuity.
This is equivalent to a pixel size of 0.3 arc-minutes! If you take a conservative 120 degrees as your horizontal field of view and 60 degrees in the vertical plane:
120 * 120 * 60 * 60 / (0.3 * 0.3)
This translates to 576 megapixels! :O!
Imagine! 576 megapixels of available image data!
Curiously – ironic to this - most people cannot distinguish the difference in quality between a 300dpi (dots per ink) and a 150dpi photo when printed at 6x4", when viewed at normal viewing distances.
So, although the human eye and brain when combined can produce massive amounts of data for imaging purposes, 150dpi output is more than enough to provide adequate data for us to accept the result as photographic quality.
How cool is that? :)
http://news.deviantart.com/article/27174/
http://www.clarkvision.com/imagedetail/eye-resolution.html
yilin-
Revelation of class test answers (:
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11:08 PM
So now, kids, I have finished marking your biology spring tests, and we are going to go through them now! Applause please!
*Groans from class*
And here are the long-awaited answers!
Please check your answers and come to me for any mark discrepancies! :D
rachel [4F/23] --*
Quotes!!!
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10:52 PM
Interesting quotes on the eye! Enjoy!
There are many things in life that will catch your eye, but only a few will catch your heart...pursue those.
- Michael Nolan
He who experiences the unity of life sees his own self in all beings, and all beings in his own Self, and looks on everything with an impartial eye.
-Buddha quotes
For every beauty there is an eye somewhere to see it. For every truth there is an ear somewhere to hear it. For every love there is a heart somewhere to receive it.
-Ivan Panin
The sun illuminates only the eye of the man, but shines into the eye and the heart of the child
-Ralph Waldo Emerson
The loveliest faces are to be seen by moonlight, when one sees half with the eye and half with the fancy.
-Persian Proverb quotes
Few people know how to take a walk. The qualifications are endurance, plain clothes, old shoes, an eye for nature, good humor, vast curiosity, good speech, good silence and nothing too much
-Ralph Waldo Emerson
And now here is my secret, a very simple secret; it is only with the heart that one can see rightly, what is essential is invisible to the eye.
-Antoine de Saint-Exupery
An eye for eye only ends up making the whole world blind.
-Mahatma Gandhi
Never bend your head. Always hold it high. Look the world straight in the eye.
-Helen Keller
Nature will bear the closest inspection. She invites us to lay our eye level with her smallest leaf, and take an insect view of its plain.
-Henry David Thoreau
Why does the eye see a thing more clearly in dreams than the imagination when awake?
-Leonardo da Vinci
Love is not blind; it is an extra eye, which shows us what is most worthy of regard.
-James Matthew Barrie
All things, oh priests, are on fire . . . The eye is on fire; forms are on fire; eye-consciousness is on fire; impressions received by the eye are on fire.
-Buddha quotes (Hindu Prince Gautama Siddharta, the founder of Buddhism, 563-483 B.C.)
To the attentive eye, each moment of the year has its own beauty, and in the same field, it beholds, every hour, a picture which was never seen before, and which shall never be seen again.
-Ralph Waldo Emerson
If the eye does not want to see, neither light nor glasses will help
-German Proverb quotes
All that we do is done with an eye to something else
-Aristotle quotes
There are moments when, even to the sober eye of Reason, the world of our sad humanity must assume the aspect of Hell
-Edgar Allan Poe
Every closed eye is not sleeping, and every open eye is not seeing.
-Bill Cosby
Never look down to test the ground before taking your next step; only he who keeps his eye fixed on the far horizon will find the right road.
-Dag Hammarskjold
The eye of a master will do more work than both his hands
-Benjamin Franklin
An eye can threaten like a loaded and levelled gun, or it can insult like hissing or kicking; or, in its altered mood, by beams of kindness, it can make the heart dance for joy
-Ralph Waldo Emerson
The eye of a human being is a microscope, which makes the world seem bigger than it really is.
-Kahlil Gibran
What the eye does not see, the heart does not rue
-Mary Collyer
The way to see by Faith is to shut the Eye of Reason.
-Benjamin Franklin
The eye altering, alters all.
-William Blake
Be slow of tongue and quick of eye.
-Miguel de Cervantes Saavedra
In marriage the eye finds, the heart chooses, the hand binds, and death looses.
-Anonymous
Faults are beauties in a lover’s eye.
-Theocritus quotes
For every beauty there is an eye somewhere to see it.
-Anonymous
We hardly ever realize that we can cut anything out of our lives, anytime, in the blink of an eye.
-Carlos Castaneda
-Gui Ju 4F (10)
credits:http://thinkexist.com/quotes/with/keyword/eye