how the eye works experiment

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Teaching Resources & Guides > Science Lessons > Eyes & Vision  

Eyes & Vision

Do you know how your vision works?

Read on to find out about the incredible properties of the eye–and how its features affect your vision.

Eyes & Vision Science Lesson

Eye anatomy.

The human eye is one of the the most complex and sophisticated sensory organs in the body.

Its unique automatic focusing system outstrips that of any camera, and its light sensitivity is ten million times greater than the best film designed so far! Before taking a look at how the eye works, let’s start with a basic overview of how it is built.

The outside layer of the eye is made up of the sclera and the cornea.

The sclera is the firm white tissue that covers all of the eye except the very front. It helps maintain the shape of the eye and protects the inner parts.

The cornea is the transparent portion at the center front part of the eye that allows light through.

A thin outer mucous membrane called the conjunctiva covers the inside of the eyelids, the cornea, and the front portion of the sclera. It helps lubricate the eye.

The middle layer of the eye contains oxygen- and nutrient-rich blood vessels, most of which are located in the layer of tissue called the choroid .

Near the front of the eye is the ciliary body , a group of muscles and ligaments that attach to the lens. These muscles change the shape of the lens as they relax and contract.

The final component of this layer is the iris , a group of muscles that controls how much light enters the eye by adjusting the opening, or pupil . The iris contains pigments that determine your eye-color.

When you look at a person’s eye, you can see parts from each of the first two layers: the “white” of the eye is the sclera, the front transparent part is the cornea, the iris is the colored part, and the pupil is the dark hole in the center.

The eye’s inner layer is composed of the retina : thin tissue that contains blood vessels and light-sensitive photoreceptor cells called rods and cones.

Every human eye contains about 120 million rods and 7 million cones.

The rods are very sensitive to low-level light, but they cannot distinguish color.

Cones need much more light to function than rods do, but they provide color information and sharp detail.

You may have noticed that in dim light color looks much less vibrant; that is because the rods that help you see in the dark are more or less “color-blind.” The retina also contains a dark pigment called melanin (also found in skin and hair cells) – this reduces reflection of light when it enters your eye.

The blood vessels and the optic nerve (the nerve that conducts electrical impulses to the brain; see the following article to learn more) connect to the retina at a spot called the optic disc .

On this disc there are no rods and cones; this is your blind spot. You don’t usually notice your blind spot, because your two eyes work together to “cover up” each other’s blind spot.

The macula is a small spot in the center of your retina. On this spot is a small pit called the fovea . When light is focused on this spot we get the sharpest image, because the fovea contains very tightly-packed photoreceptor cells. Macular degeneration is a common eye disease that is caused by the deterioration of the macula and results in partial blindness.

The three layers fill only a small part of the eye; the large middle area isn’t empty, though! The area between the cornea and the lens is filled with a transparent liquid material called the aqueous humor. The area between the lens and the retina contains a clear gel-like substance called the vitreous humor. Both of these humors help give shape to the eye and are part of the focusing process.

Your eye is a very delicate organ. The sclera and cornea protect the inner parts of the eye, but there are other protective parts as well.

Most obvious are your eyelids. With the eyelashes , your eyelids help keep outside particles from getting in your eye.

They also help spread tears , which keep the eye moist and wash away anything that gets past the eyelids. Tears are produced in the lacrimal glands and contain antibodies and anti-bacterial enzymes. The tears that your lacrimal glands produce regularly are drained away into the nasal cavity.

When you produce extra tears, though, they will spill out – this is called crying!

How Vision Works

In order to see, your eye must focus light on the retina, convert the light into electrical impulses, and send those impulses to your brain to be interpreted.

It is an amazing and complex process, but you do it constantly without even trying!

Focusing the light. When light bounces off an object and reaches the eye, it must be bent so that its rays arrive at the retina in focus.

Four different surfaces bend the light as it enters the eye: the cornea, the aqueous humor, the lens, and the vitreous humor.

When all four of these bend the light appropriately, you see a focused image of the object.

The eye can focus objects at different distances because the ciliary muscles push and pull to make the lens change shape. When you look at an object that is far away, the ciliary muscles relax and the lens has a flattened shape.

When you look at an object that is close by, the ciliary muscles are contracted and the lens is thickened. This is one of the features that makes the eye superior to any manmade camera.

To adjust a camera lens for the distance of an object, you must move the whole lens forward or back. If our eyes worked the same way, we would need long tubes sticking out of our eyes so the lenses could move back and forth.

Instead, our lenses just change shape to adjust for the distance of an object. This takes up much less room, and is probably more attractive!

In addition to focusing the light, your eye can control how much light gets in.

The colored part of your eye, called the iris, controls the size of the pupil, the opening that lets light through.

In dim light, the iris will cause your pupil to expand, allowing as much light as possible into your eye. In bright light, the iris causes the pupil to contract so that less light can enter.

Converting the light. What happens when the focused light reaches your retina? It triggers a complex chemical reaction in the light-sensitive rod and cone cells.

Rods contain a chemical called rhodopsin , or “visual purple,” and cones contain chemicals called color pigments.

These chemicals undergo a transformation that results in electrical impulses being sent to the brain through the optic nerve.

Interpreting in the brain. When the electrical impulses arrive in the visual cortex of the brain, the brain analyzes the color and light information from the rods and cones and interprets them as light.

The brain flips the image (the light was projected on your retina upside down) and fills in for the blind spot if necessary (read more on this in the science project below).

All this happens almost instantaneously, allowing you to read a book or enjoy a beautiful sunset. Some of the information from the retina is sent to the visual reflex system in your brain. This allows you to react quickly to visual threats.

If you see something coming toward your head, your visual reflex system processes this and causes you to duck before you have time to think about it!

Eyes & Vision Science Projects

Eye chart vision test.

A Snellen eye chart is used to determine how “normal” your vision is. It sets a standard for what most people should be able to see when they stand 20 feet away from the chart.

20/20 vision just means that when you stand 20 feet away from a Snellen eye chart, you see what a normal human being can see.

If you see 20/40, that means that when you stand 20 feet away from the chart, you see what a normal person sees standing 40 feet away from it. The higher the second number, the worse your vision is. 20/200 (you see at 20 feet what a normal person sees at 200) is the number for legal blindness in the United States.

20/20 vision isn’t perfect, it’s just “normal.” You can have better vision than 20/20. If you have 20/10 you see at 20 feet what most people see at 10. Some animals, like hawks, might have 20/2 vision!

You can use our Snellen eye chart * to compare vision within your family or with your friends.

(This will only give you an approximate idea of your vision. Your optometrist has much more precise tools to find out exactly how well you can see.)

Each line of the chart is labeled on the left side. The second to last line is 20/20.

Tape the eye chart to a wall, making sure it is in plenty of light. Stand twenty feet away from the chart and begin reading each line.

Have a family member or friend watch to see that you are reading each letter correctly. The last line that you are able to read will give you an approximate idea of your vision.

If you can read the very bottom line, your vision is 20/10! Now try covering one eye and just testing the other one. Is one eye better than the other?

Have all of your family members try reading the chart. Do some of you have better vision than others? If you wear glasses, what is your vision with them on and what is it without them?

* Instructions for downloading : The Snellen Eye Chart PDF is 11″ x 17″, so to print correctly you will need to set your print options to “tile.” Printer choices will vary, but you should do something similar to this. Open the PDF and choose Print. Under the page scaling options, select “tile all pages.” This should print the chart on four sheets of paper. You will need to trim the edges so the pieces match up, and then tape or glue them together.

(You can also order an already-printed 11″ x 17″ copy of our Snellen Eye Chart.)

Blind Spot Experiments

The spot where your optic nerve connects to your retina is called the optic disc. There are no photoreceptor cells on this disc, so when an image hits that part of your retina, you can’t see it.

This is your blind spot. You don’t notice this blind spot in every-day life, because your two eyes work together to cover it up.

To find it, draw a filled-in, 1/4″-sized square and a circle three or four inches apart on a piece of white paper.

Hold the paper at arm’s length and close your left eye. Focus on the square with your right eye, and slowly move the paper toward you. When the circle reaches your blind spot, it will disappear!

Try again to find the blind spot for your other eye. Close your right eye and focus on the circle with your left eye. Move the paper until the square disappears.

What happened when the circle disappeared? Did you see nothing where the circle had been?

No, when the circle disappeared, you saw a plain white background that matched the rest of the sheet of paper.

This is because your brain “filled in” for the blind spot – your eye didn’t send any information about that part of the paper, so the brain just made the “hole” match the rest.

Try the experiment again on a piece of colored paper. When the circle disappears, the brain will fill in whatever color matches the rest of the paper.

The brain doesn’t just match colored backgrounds. It can also make other changes to what you see. Try drawing two filled-in rectangles side by side with a circle in between them. A few inches to the right of this, draw a square.

Close your right eye and focus your left eye on the square. Move the paper until the circle disappears and the two separated bars become one bar.

How did that happen? The circle in between the bars fell on your blind spot. When it disappeared, the brain filled in for the missing information by connecting the two bars!

Here is one final experiment with your blind spot. In this instance the brain doesn’t match the blind spot with its immediate white background, but instead with the pattern surrounding it.

Draw a line down the center of your page. On one side draw a small square and on the other draw rows of circles. Color the center circle red and all the others blue.

Close your left eye and look at the square with your right eye. As you move the paper, the red circle should disappear and be replaced by a blue one!

Technology: Improving Eyesight

The general design of the human eye is practically flawless – but each individual eye isn’t.

If you are using contacts or glasses to read this article, you know that your eyes aren’t perfect.

Perhaps you are nearsighted and can’t see objects that are far away very well.

Or maybe you are farsighted and have trouble seeing things close-up. Both of these conditions occur because of the shape of the eyeball.

If your eyeball is too short, the light rays will focus the image behind your retina, instead of on it. This produces farsightedness. If your eyeball is too long, the light rays focus the image in front of the retina, making you nearsighted.

The technology of vision correction has developed over centuries.

The first known eyeglasses were made in the 13th century out of quartz set into bone, metal, or leather.

Eventually the technology for glass-blowing allowed a fine enough quality of glass to be used for lenses.

The biggest problem with these early glasses was keeping them on. It took almost 400 years before someone developed the side arms to rest on the ears!

Most people bought ready-made glasses that would have helped their vision without correcting it precisely.

For example, Benjamin Franklin had two pair of glasses, one for near and one for far. He got tired of changing them, so he cut the lenses in half and repositioned them so that he could see both near and far using the same glasses – the first bifocals!

With the advance of technology, vision-testing equipment has become more and more precise.

Now to obtain a pair of glasses, you must go to an optometrist who will determine exactly what type and strength of lenses you need.

Concave lenses are used for nearsightedness because they bend light away from the center – this stops the light from focusing too far in front of the retina.

Convex lenses are used for farsightedness because they bend light toward the center, causing the light to focus sooner so the image is not focused behind your retina.

Lenses can also be made that will correct other problems in the eye, such as astigmatism , which is an irregular curvature of the cornea.

Contact lenses are a popular alternative to eyeglasses. These lenses fit directly on the cornea, where they “float” on a layer of tears.

They were under experimentation as early as the mid-19th century, though quality and comfort left much to be desired. Now millions of people in the United States use either soft or hard lenses.

Soft contact lenses are made of flexible, water-absorbing plastics. They are more comfortable to wear than hard lenses, which are made of more rigid plastic that does not form to the eye as well. Hard lenses, on the other hand, produce a sharper image.

Some people want a more permanent solution to their vision problems. In recent years, procedures such as LASIK (laser-assisted in-situ keratomileusis) surgery have been developed to remove the need for external lenses like glasses and contacts.

While external lenses change how the light is bent so that it focuses on your retina, laser surgery reshapes the cornea itself.

The process involves a tightly focused beam of ultraviolet light, called an excimer laser. The surgeon first uses a sharp scalpel to cut a flap in the top layer of the cornea, then directs the laser into the middle layer.

As the laser pulses onto this surface, it vaporizes a microscopic portion of the cornea. By controlling the number and location of the pulses, the surgeon controls how much of the cornea is removed.

Noteworthy Scientist: Charles Bell (1774-1842)

Do you ever wonder how great artists can paint a human face that looks perfectly realistic? One of Charles Bell’s contributions to art was an anatomy textbook especially for artists, called Essays on the Anatomy of Expression in Painting .

Charles Bell was an artist himself, as well as a surgeon and anatomist. He was born in Edinburgh, Scotland, the son of a Church of England minister.  His older brother John was a surgeon, author, and teacher of anatomy at the University of Edinburgh.

Studying with his brother, Bell developed both his artistic talent and his medical knowledge. After he graduated from the University with a degree in medicine, Bell assisted in teaching his brother’s anatomy class and publishing a four-volume Anatomy textbook.

Eventually Bell moved to London where he did extensive research on nerves, wrote many books and treatises, opened a school of anatomy, and worked as a surgeon.

In 1815 he cared for the wounded after the bloody battle of Waterloo, his skill in surgery holding him in good stead.

His battlefield experience led him to create illustrations of gunshot wounds to be used by surgeons.

Bell’s research on the brain and nerves proved foundational for modern neurology.  He determined that nerves only sent information one way: some took sensory information to the brain, and some took commands from the brain to the rest of the body. He also traced nerves from special sensory organs (such as the eye) to specific parts of the brain.

Through all his research and medical illustration, Bell recognized the hand of a Creator. In 1836 he was invited to contribute to a collection of works “On the Power, Wisdom, and Goodness of God as Manifested in the Creation.”

He agreed, and wrote a treatise called The Hand; its Mechanism and Vital Endowment, as Evincing Design .

Bell was knighted by King William IV in 1831, and in 1835 he accepted a position as professor of surgery and returned to Scotland.

He continued to work in his field up until his death in 1842.

More on Eyes & Vision:

•  Eyesight for Young Students
•   Two Eyes (vs One)
•  Cow Eye Dissection

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Science Fun

How Does An Eye Work Human Body Experiment

In this fun and easy science experiment, we’re going to explore and investigate the human body and how eyes work. 

• Rubber band

Instructions:

• Using the safety pin, poke a small hole in the center of the bottom of the paper cup.
• Place a piece of the wax paper over the mouth of the cup.
• Use the rubber band to hold the wax paper in place.
• Point the bottom of the paper cup at a bright light from about two to three feet away.
• Slowly walk toward the light and you should soon see an image of the light bulb appear upside down on the wax paper.

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How it Works:

Light enters our eyes through our pupils after it reflects off of an object. The light then makes it way through the different parts of our eyes and produces an image on our retina that is upside down. The image then travels to our brain through the optic nerve. Our brain compensates by reversing the image so that it is right-side up so we do not see an upside down image. In a pinhole viewer, the light enters through the small pinhole we made in the bottom of the cup. This is similar to the way that light enters the eye through the pupil. The light creates an image on the wax paper, similar to the way that light creates an image on the retina of the eye. Our pinhole viewer lacks a “brain” to “correct” the image, so it will appear upside down on the wax paper.

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Try a white plastic grocery bag. Try tracing paper. Try tissue paper. 

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How the Human Eye Works – Step by Step

Humans eyes work much like cameras. Here is a simple step-by-step explanation of how the human eye works and a look at the structure and function of the parts of the eye.

Parts of the Eye and Their Functions

To understand how the human eye works, you need to know the names and functions of its structures.

• Cornea : The cornea is the transparent outer surface of the eye. Because the eyeball is round, the cornea acts as a lens that bends or refracts light. Corneal cells regenerate quickly, because the cornea is exposed to the environment. But, the layer is thin enough to allow oxygen into the deeper structures.
• Aqueous Humor : The aqueous humor is the fluid layer below the cornea. It has a composition similar to human plasma. The aqueous human shapes the cornea and nourishes the cells of the eye.
• Iris and Pupil : Light passes through the cornea and aqueous humor through a hole called the pupil. The iris is a contractile ring that determines eye color and controls the size of the pupil. The iris dilates (opens) the pupil in low light so more light enters the eye and constricts in bright light.
• Lens : While the cornea initially focuses light, the lens makes it so you can change focus between near and distant objects. Ciliary muscles around the lens contract to thicken the lens to focus on near objects. The muscles relax to flatten the lens to focus on distant objects.
• Vitreous Humor : The vitreous humor is a transparent gel that fills the eye. It supports the shape of the eye and provides enough distance so that the lens can focus.
• Retina : The retina is the coating on the inside of the back of the eye. It contains two types of cells. Rods detect light and help form images in dim light. Cones detect colors. There are three types of cones. They are called red, green, and blue cones, but they actually detect a range of wavelengths of light and not just the colors for which they are named.
• Fovea : The fovea is the circle of cells on the retina responsible for clear focus. This region is rich with cones, so it allows sharp color vision. Rods outside the fovea are largely responsible for peripheral vision.
• Optic Nerve : Light striking a rod or cone produces an electrochemical signal. The cells transmit this signal through the optic nerve to the brain.
• Brain : The visual cortex of the brain receives nerve impulses from both eyes and compares them to construct a three-dimensional image. Because the eye is like a camera, the true image formed on the retina is inverted (upside down). The brain automatically rights the image.

How the Human Eye Works

Now that you know the names of the parts of the eye, it’s easy to follow the steps leading to vision.

• Cornea : Light enters the eye through the cornea. Because of the shape of the cornea, it exits pre-focused.
• Aqueous Humor/Pupil : From the cornea, light passes through the aqueous humor and through the pupil.
• Lens : From here, light strikes the lens. The lens further focuses light, depending on whether you’re looking at a near or distant object. Light exits the lens and passes through the vitreous humor.
• Vitreous Humor : Ideally, the vitreous humor is clear and allows light to travel unimpeded to the retina.
• Retina : Light reaches the retina, activating rods and cones to generate electrical impulses that code for an inverted image.
• Optic Nerve : Signals from the rods and cones travel through the optic nerve to the brain.
• Brain : The brain compares left/right vision to add depth and make the image three-dimensional. It also flips the image so it appears right-side up.

Common Eye Problems

The most common eye problems are myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. These conditions affect vision, but the eyes may be perfectly healthy.

• Myopia : Nearsightedness occurs when the focal point of the eye is in front of the retina. In other words, the eye is narrow rather than spherical.
• Hyperopia : Farsightedness occurs when the focal point of the eye is past the retina. In other words, the eye is slightly flattened rather than spherical.
• Presbyopia : Presbyopia is age-related farsightedness. It’s caused by stiffening of the eye’s lens over time. Presbyopia often improves myopia.
• Astigmatism : Astigmatism occurs when the eye curvature isn’t perfectly spherical. This makes light focus unevenly from one part of the eye to another.

Other common eye problems include glaucoma, cataracts, and macular degeneration. These conditions can lead to blindness.

• Cataracts : Cataracts are clouding and hardening of the lens.
• Macular Degeneration : Macular degeneration is progressive degeneration of the retina.
• Glaucoma : Glaucoma is increased fluid pressure within the eye. This can damage the optic nerve.

Interesting Eye Facts

Here are some fun and interesting eye facts you may not know:

• Babies are born with full-sized eyes. Eye size remains the same from birth until death.
• Blind people with eyes may still be able to sense light and dark . This is because there are cells in the eyes that detect light, but aren’t involved in image formation.
• Each eye has a blind spot where the eye attaches to the optic nerve. If you close one eye, you can find the blind spot. Normally, the second eye compensates and fills in the hole in your vision.
• The reason total eye transplants aren’t possible is because it’s presently too difficult to make the million-plus connections in the optic nerve.
• Humans don’t ordinarily see ultraviolet light , but the retina can detect it. The lens absorbs UV light before it reaches the retina, presumably to protect it from the high energy light capable of damaging rods and cones. However, people with artificial lenses report seeing ultraviolet.
• Blue eyes don’t contain any blue pigment. Instead, they lack pigment found in other eye colors. Rayleigh scattering of light causes the blue color in the same way as it makes the sky appear blue .
• Eye color can change over time. Usually, color change occurs from hormonal changes or chemical reactions from medications.
• Bito, L. Z.; Matheny, A.; Cruickshanks, K. J.; Nondahl, D. M.; Carino, O. B. (1997). “Eye Color Changes Past Early Childhood”.  Archives of Ophthalmology .  115  (5): 659–63. 
• Goldsmith, T. H. (1990). “Optimization, Constraint, and History in the Evolution of Eyes”.  The Quarterly Review of Biology .  65 (3): 281–322.

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Neuroscience for Everyone!

• Experiments

Experiment: How Your Eye Detects Color and Motion

Everyday your eyes and brain work together to create vision. But how does this all really happen? What role does your brain and eyes play in the creation of perceiving everything around you?. How does your visual system render color and how is motion captured? Follow along in this lesson plan and find out the answer to some of these questions and many more.

What will you learn?

In this lesson you will learn how your visual system interacts with your brain. The experiment will show you how your visual system detects and interprets motion/color.

Prerequisite Labs

You build everything yourself from household materials.

Light is the key to vision. The photons emitted from a light source bounce off of objects and eventually hit you in the eye! When a photon reaches your eye it passes through the transparent cornea and then through the lens which refracts and focuses the light onto your retina, where the light is selectively detected and absorbed by special photoreceptor cells: the rods and cones. After these photoreceptors transform the light into an electrical signal, nerves carry the signal into your brain, where some very complicated and awesome things occur, but we will discuss those in a later experiment.

Where does vision really start? The best answer would be with the photoreceptors that line your retina, the rods and cones! The retina, making up the back portion of each eye, is layered with approximately 90 million rods and 4.5 million cone! They get their names largely from the shape of their structure, not their discoverers (there is no Dr. Rod and Dr. Cone). However, Dr. Osterberg in 1935 first counted 120 million rods and 6 million cones, but in 1990 the number was updated with advances in microscopic computer imaging.

Your rods and cones work well together, and this is good for you. Both have diverse skills, functions, and placement in the retina. Rods are great at sensing movement, especially in dim light situations. Unfortunately, they do not sense color or focus well. Luckily, your cones have high color acuity and focus very well, especially in bright conditions. Most of your cones are centered around or in the fovea, which is a small dimple on the center of the retina. When you focus your eyes, for example reading or performing a science experiment, light entering your eye is being centered mainly on your fovea. The fovea consists of roughly thirty thousand specialized cones that are slightly smaller than other cones. There are also different subtypes of cones: each tuned to better absorb a different portion of the visible light spectrum: short wavelength (blue), middle (green), and long (red).

Below are pictures of your retina as if you were standing in front and facing it. Notice that each picture depicts a different part of your retina. They are divided in three pictures for ease of viewing, but in reality all three would overlap. Can you tell which retina is pictured below? Is it your left or right retina, how can you tell?

The optic disk/nerve has no rods nor cones as it is packed full of nerves traveling to the brain. The arteries supply fresh blood and nutrients to the eye. The Fovea has no rods, but it is full of cones.

How do your rods and cones transform light into electrical signals? They use special proteins called opsins , which turn the photons absorbed by the Rods and Cones into specific electrochemical signals that are then sent to the optic nerve and eventually the brain. This process is called Phototransduction and human vision has four essential types of opsin: one for rods and three for the cones. In your photoreceptors (your rods and cones), opsins are coupled with vitamin A (found in carrots). Vitamin A acts as a light absorbing molecule; after absorbing light its molecular structure changes and it separates from the opsin. As this separating occurs, an electrical signal is generated by the opsin in a very complex biochemical process known as the visual cycle.

Now that you have a foundation in eye anatomy/physiology, you are going to conduct an experiment with a friend of yours. This experiment will showcase the different specialties of your photoreceptors as well as their placement along your retina.

For this experiment you need:

Making the posterboard.

Making the Sticks

Now that you have materials ready, your group is good to go. One member will act as the subject and hold the poster board and the other one will record the data. You will carry out the experiment two times so that each member plays each role. Below is that chart that you will use for recording:

Experiment Steps

Questions to Consider

NOTIFICATIONS

How the eye works.

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Associate Professor Gordon Sanderson is Associate Professor in the Department of Ophthalmology at the University of Otago, Dunedin. He explains how the eye works, focusing on the receptors located in the retina at the back of the eye. There are two types of receptor – rods and cones – that allow us to see in black and white (rods) as well as in colour (cones).

ASSOCIATE PROFESSOR GORDON SANDERSON You’ve got a retina which is obviously the receptor – that’s the bit that receives all the images and takes the light bits and the dark bits and sorts them all out. But to get an image on that retina, you need a lens – you need a focusing system to make it look clear, and that’s essentially what the eye is doing.

In the front of it it’s got a cornea, which is part of the lens system, and then inside of it, it’s got a lens, which is the other component, and between them they focus a very clear image on the retina, which is at the back.

And from there, the images go down the optic nerve and ultimately to the back of your head, and that’s the bit that interprets the images for you.

The eye has actually only got two receptors – you’ve got rods and you’ve got cones. We’ll dismiss the rods straight away, because all they do is provide you with your peripheral vision. They will detect movement, and they’re actually black and white, so not able to detect colour. In the centre, you’ve got the cones, and the cones are the most sensitive receptors. They’re the ones that pick up the fine detail but they also pick up colour.

Now there are actually three types of cones. You’ve got the same as you have with the video monitor – red, green and blue – but they working in reverse, so they’re receiving red, they’re receiving green, they’re receiving blue, and they convert various components of red and green and blue and make the shades of colour that we’re all familiar with. Part of that processing is actually done on the retina, but part of it takes place behind the retina and even more takes place in what’s called the mid-brain, and then ultimately the visual cortex kind of receives the image and assembles it and turns it into stereoscopic imagery or visual memory or motion or form or whatever it is that we’re actually concerned about. But the whole thing is a massively complex composite of all these stimuli all derived from three receptors.

The cones have got their own personal nerve fibres. By the time you get out to the peripheral retina, there might be 20 or 40 000 rods per nerve fibre, so that’s why my peripheral vision is a lot worse that my central vision. People tend to think that, because you’ve got a composite image that your retina or your brain is receiving a photographic image. It isn’t. It’s actually only receiving a very clear part in the centre. It’s because you moved around and built up this sort of photographic memory if you like of what the room looks like that you think everything is clear.

Colours of light

Light is made up of wavelengths of light, and each wavelength is a particular colour. The colour we see is a result of which wavelengths are reflected back to our eyes. Visible light Visible ...

How the eye focuses light

The human eye is a sense organ adapted to allow vision by reacting to light. The cornea and the crystalline lens are both important for the eye to focus light. The eye focuses light in a similar ...

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How the Eyes Work

The human eye is almost as big as a Ping-Pong ball and weighs about one-quarter of an ounce.

5:09 · Human Body

Despite its small size, the eye is a complex machine that feeds data to the brain at lightning speed. Light enters the eye through the cornea and passes through the pupil to the lens. The lens focuses the rays onto the retina, but images on the retina are upside down, reversed, and two-dimensional. 

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• Human Eye Science Project Ideas

Brain Lesson Plans for Children

The human eye is an amazing sense organ that allows us to see and make decisions based on what we see. It allows us to appreciate colors, facial expressions and beauty, as well as things than can negatively effect our emotions. Without our eyes, we would not be able to do all the things we do in a single day, such as read, drive or work on computers. Science fair projects that involve the human eye can give students information into how the eye works as well as how outside factors may effect the eye and its important function.

Anatomy of the Eye

The eye is an organ with highly specialized cells that work both individually and together to form vision. Students can research the shape of the eye and information about how each part contributes to vision. They can experiment to see what happens if one of the steps in vision changes, such as altering the shape of the lens. Other ideas include teardrops--researching how are they formed and what are they made of. Measure peripheral vision and eye shape. Explore how the pupil changes size to control the light entering the eye. Can the brain work with the eye to retain a series of images to make a single picture? On higher level, research if corrective lenses have any impact on the ability to see hidden 3-D pictures.

Other Anatomy Ideas

Form an experiment around other anatomical issues such as gender or age and how they might affect eyesight. Do male and female test subjects show any difference in the ability to see peripherally, see illusions or more accurate depth perception? Discuss if pupil color has any effect on vision. Does age or gender affect selective visual attention? Is there are correlation between hand dominance and eye dominance? Research if the blind spot is more perceptible to any group of people according to age or gender.

The Eye and Psychology

The eyes and how what you see influences your thoughts would be a very interesting subject for older students to study. Study the affect that emotional images, both positive and negative, might have on pupil size. Does the color of the room have any affect on the emotions? Can you change a person's emotional state by using a specific color? Does pupil size change with interest in a subject?

The world of illusions or tricks of the eye and mind can be a great place to find experiments. Research magic tricks and illusions to explain how and why they work. Do gifted people see optical illusions any differently than the general population? Can their minds decipher tricks played on their eyes? Make a flip-book animation and explain the perception of motion used in the illusion.

Colors are something our eyes see every moment of every day. Can they affect things such as blood pressure, appetite or the urge to spend money? What is color blindness and is it more prevalent in any one gender or age group and can it be inherited? Determine if all the cells that perceive color in the eye such as cones and rods, tire at the same rate. Can color affect the mind's interpretation of how a food or drink tastes?

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Susan King is a teacher with 27 years experience with all ages, grade levels and ability levels, including teaching in China. She has written a book, "The Road to Rebecca," about adopting from China. She graduated from Texas A&M University. She also has a ThM from Colorado Theological Seminary in Christian Counseling and recently received her PhD.

Sense of Sight: Part 1.

Eye Anatomy and Function Developed by Marjorie A. Murray, Ph.D.; Neuroscience for Kids Staff Writer |

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Students learn some ways to investigate the sense of sight, and find out how to plan and conduct their own experiments.	for these activities: 45 minutes for introducing and discussing the activity, 45 minutes for the "Class Experiment;" and 45 minutes for Explor Time and "Try Your Own Experiment."

Our visual systems perform all kinds of amazing jobs, from finding constellations in the night sky, to picking out just the right strawberry in the supermarket, to tracking a fly ball into a waiting glove. How do our eyes and brains recognize shape, movement, depth, and color? How do we so easily pick a friend's face out of a crowd, yet get fooled by optical illusions? In this first of three units on the Sense of Sight, we consider the anatomy and physiology of the eye, especially the retina, and the initial pathways visual information takes to the brain. Part 2 discusses how various aspects of a visual scene are processed at higher levels, and Part 3 delves into color vision. Most animals and many plants are photosensitive; that is, they can detect different light intensities. Some organisms accomplish this with single cells or with simple eyes that do not form images but do allow the organism to react to light by moving toward or away from it. In order for an eye to transmit more information about the world, however, it must have a way of forming an image, a representation of the scene being viewed. The mammalian eyeball (Figure 2) is an organ that focuses a visual scene onto a sheet of specialized neural tissue, the retina, which lines the back of the eye. Light from a scene passes through the cornea, pupil, and lens on its way to the retina. The cornea and lens focus light from objects onto photoreceptors, which absorb and then convert it into electrical signals that carry information to the brain. Two pockets of transparent fluid nourish eye tissues and maintain constant eye shape: these are the aqueous and vitreous humors, through which the light also passes. The lens projects an inverted image onto the retina in the same way a camera lens projects an inverted image onto film; the brain adjusts this inversion so we see the world in its correct orientation. To control the images that fall upon our retinas, we can either turn our heads or turn our eyes independently of our heads by contracting the extraocular muscles, six bands of muscles that attach to the tough outside covering, or sclera, of the eyeball and are innervated by cranial nerves. See Table 1 for a brief list of eyeball components and their functions. The cornea and lens bend or refract light rays as they enter the eye, in order to focus images on the retina. The eye can change the extent to which rays are bent and thus can focus images of objects that are various distances from the observer, by varying the curvature of the lens. The ciliary muscle accomplishes this by contracting to lessen tension on the lens and allowing it to round up so it can bend light rays more, or relaxing for the opposite effect. This ciliary muscle is smooth or non-voluntary muscle-you cannot "decide" to contract or relax it as you do the skeletal muscle in a finger or facial muscle. Refractive errors occur when the bending of light rays by the cornea and lens does not focus the image correctly onto the retina. An eyeball that is too long or too short for the optics of the cornea and lens or an irregularly shaped cornea can cause refractive errors, which include myopia (near-sightedness), hyperopia (far-sightedness), and astigmatism. Myopia results either when the eyeball is too long or when the cornea is curved too much, and the focused image falls in front of the retina. Hyperopia is the opposite, with the image falling behind the retina. Astigmatism results from a cornea that is not spherical. Fortunately, most refractive errors can be corrected with prescription lenses. TABLE 1. PARTS OF THE EYE FUNCTION Aqueous humor clear watery fluid found in the anterior chamber of the eye; maintains pressure and nourishes the cornea and lens Vitreous humor clear, jelly-like fluid found in the back portion of the eye: maintains shape of the eye and attaches to the retina Blind spot small area of the retina where the optic nerve leaves the eye: any image falling here will not be seen Ciliary muscles involuntary muscles that change the lens shape to allow focusing images of objects at different distances Cornea transparent tissue covering the front of the eye: does not have blood vessels; does have nerves Cones photoreceptors responsive to color and in bright conditions; used for fine detail Rods photoreceptors responsive in low light conditions; not useful for fine detail Fovea central part of the macula that provides sharpest vision; contains only cones Iris circular band of muscles that controls the size of the pupil. The pigmentation of the iris gives "color" to the eye. Blue eyes have the least amount of pigment; brown eyes have the most Lens transparent tissue that bends light passing through the eye: to focus light, the lens can change shape Macula small central area of the retina that provides vision for fine work and reading Optic nerve bundle of over one million axons from ganglion cells that carry visual signals from the eye to the brain Pupil hole in the center of the eye where light passes through Choroid Thin tissue layer containing blood vessels, sandwiched between the sclera and retina; also, because of the high melanocytes content, the choroid acts as a light-absorbing layer. Retina layer of tissue on the back portion of the eye that contains cells responsive to light (photoreceptors) Sclera tough, white outer covering of the eyeball; extraocular muscles attach here to move the eye Science experiments lend themselves to a "let's see what happens" atmosphere, and a good way to take advantage of this is to provide Explore Time or Brainstorming Time. Many labs benefit from Explore Time, when students are free to investigate lab supplies that are out on a table, and begin to think about how to use them in experiments. Because of their curiosity, students usually "play" with lab materials first even in a more traditional lab, so taking advantage of this natural behavior is usually successful. Explore Time can occur either before the Class Experiment or before the "Try Your Own Experiment" activity, depending on the plans of the teacher. To use Explore Time before the Class Experiment, set the lab supplies out on a bench before giving instructions for the experiment. Ask the students how these materials could be used to investigate the sense of sight in light of the previous lecture and discussion, then offer 10 or 15 minutes for investigating the materials. Give some basic safety precautions, then circulate among students to answer questions and encourage hypotheses. After students gain an interest in the materials and subject, lead the class into the Class Experiment with the Teacher Demonstration and help them to formulate the Lab Question. (See the accompanying Teacher Guide.) Alternately, conduct the Class Experiment in a more traditional way, and give students Explore Time before the "Try Your Own Experiment" activity. WWW references: from Neuroscience for Kids and from Neuroscience for Kids from the Howard Hughes Medical Institute By reaching Project 2061 Benchmarks for Science Literacy, students will also fulfill many of the National Science Education Standards and individual state standards for understanding the content and applying the methods of science. Because the Benchmarks most clearly state what is expected of students, they are used here. The Benchmarks are now on-line at: The Benchmarks are listed by chapter, grade level, and item number; for instance, 1A, 6-8, #1 indicates Chapter 1, section A, grades 6-8, benchmark 1. The PROCESS OF INQUIRY used in the Eye and its Connections activities will help students reach the following summarized Benchmarks: 1A, 6-8, #1 When similar investigations give different results, the scientific challenge is to judge whether the differences are trivial or significant, and it often takes further studies to decide. 1B, 6-8, #1 Sections in The Brain and Senses Introduction How the eye works How the ear works Smell and taste The sensitivity of your skin Making connections Find the matching pairs! Brain and sense word search Brain and sense jigsaw Brain How the eye works Claim your stamp. First code: * Second code: * Third code: * Fourth code: * Fifth code: * Enter your email: * Comments This field is for validation purposes and should be left unchanged. Science Experiments DIY Projects AI Learning Hub Sense of Sight – A Few Experiments Worth Seeing October 5, 2018 by ItsySparks Mini Scientists In studying about our Fives Senses, we have enjoyed exploring our sense of touch , hearing , and taste . Our most recent exploration has been with our sense of sight.  We rely very much on our sight to move around and see things every day.  Our eyes are very complex in how they work. Home Science Tools  gives a great explanation: How do our eyes work? The little dark circle in the center of each of your eyes lets light in. It is called a pupil. If you are in a dark place where no lights at all are on, can you see anything? No, you can’t because our eyes need light to be able to see! Once the light goes in, it hits a part inside at the back of your eye that is very sensitive to light. This part is called the retina. When light touches the retina, it makes an upside-down picture of whatever you are looking at. A large nerve called the optic nerve carries the image to your brain where it gets turned around so that you see it the right way instead of upside-down! We also found a great video for kids to explain how the sense of sight works too.  Click here to view . We did a few experiments to make us think about how we use our eyes every day. Our first experiment was writing with a blindfold on.  He realized right away how challenging it was to write without using our sense of sight. Next we looked at different objects.  We used our sense of sight to describe the color and shape of each object.  We then played a fun game where we placed all of the objects on a piece of paper.  I put the blindfold over his eyes.  I removed one object.  Then he had to remember what he saw and tell me which object went missing. Our last experiment was to walk slowly with our blindfold on.  This was done carefully, with adult supervision, so if you decide to try this one, make sure  your little one  walks very slowly! A lot of conversation came out of these experiments.  We talked about how some people have impaired vision and use glasses to help see better. We talked about how some people have complete loss of vision and are blind.  I explained about how blind people or partially sighted people use braille to read and write.  You can read more about braille and the braille alphabet here . Our eyes are fascinating indeed, in the way that they work.  We rely on our eyes very much, and also from the very moment we wake up!  They sure do a lot a lot of great things for us and help us see many wonders of life and the world – make sure to take good care of them! 1 thought on “Sense of Sight – A Few Experiments Worth Seeing” Pingback:  ItsySparks | Sense of Smell – What Scent can you Sense? Leave a Reply Cancel reply Your email address will not be published. Required fields are marked * Save my name, email, and website in this browser for the next time I comment. Related Posts 8 Reasons Why Kids Should Science More [Infographic] October 9, 2018 Summer Fun Activities: Let it Snow! June 5, 2014 Easy Crafts for Kids: DIY Lava Lamp Itsy Sparks Dedicated to Igniting Young Minds, ItsySparks provides knowledge to foster learning, creativity, and exploration! Description This is a simulation demonstrating the optics of the human eye. It also shows how various lenses can be used to correct for faulty vision. Be aware that it is a simplified version of what actually happens. In the simulation, there is no bending when light moves from the air into the eye (when most of the actual bending happens). Instead, in the simulation only the bendings that happen in the lens of the eye (or in the corrective lenses) is shown. Move the object closer to or farther from the eye (drag the object or use the Object Position slider). Use the focus slider to change the shape of the lens of the eye to adjust its focal length. When the refracted rays in the eye come together on the retina, the image is in focus. In some special cases you have the option to see how corrective eyewear can be used to overcome vision problems like nearsightedness and farsightedness. Adjust the Overlay Eye Anatomy slider to see a detailed image of the anatomy of the eye. Some Questions: What is different about the rays of light that reach the eye from an object near the eye, as compared to rays that come from an object far from the eye? What is nearsightedness? In nearsightedness, what is the issue with the lens? What type of lens can correct for this? What is farsightedness? In farsightedness, what is the issue with the lens? What type of lens can correct for this? What about a person that needs bi-focals? What is the issue with the lens? What type of lens can correct for this? Open-and-go lessons that inspire kids to love science. Sign up now for tons of free lessons like this one, sign up now for a free trial through june 30, 2025. get tons of lessons. What do people who are blind see? DISCUSS (1 of 3): Why do you think some people have problems with vision? DISCUSS (2 of 3): How could we figure out how eyes work? Here’s what we came up with... The first thing we thought about was--let’s take a closer look at our own eyes! See the next slide. DISCUSS (3 of 3): Look at these eyes, and the eyes of the person next to you. What's the same? What's different? Do you think that any of the differences could explain why some people have trouble with vision, or not? Unit Reading Assessments, why does a lens make an image appear upside-down. The lenses in your eyes are known as “convex” lenses: they’re curved outward. As light rays enter the far edges of a convex lens, the light rays are bent inwards. In other words, light rays entering the top of the lens bend down toward the bottom of the retina, and light rays coming in from the bottom of the lens bend toward the top of the retina. This is why the image looks upside-down! (You might wonder: Why don’t we see everything upside-down? That is a question which puzzled scientists… learn more ! Discussion with Video Why don't we see everything upside-down. Light makes an upside-down picture on the retina of your model eye. The picture on the retina of your real eye is also upside down. So why don’t you see everything upside-down? Ask your students if they can think of an experiment that might answer this question. Here's an experiment some scientists tried. They had someone wear eyeglasses that flipped the picture in their eyes so it was right-side-up. To find out what happened, watch this video . It turns out that the answer is not in your eyes -- but in your brain. Your brain learns to make sense of the picture in your eyes -- whether it's right-side-up or upside-down. Image & Video Credits Mystery Science respects the intellectual property rights of the owners of visual assets. We make every effort to use images and videos under appropriate licenses from the owner or by reaching out to the owner to get explicit permission. If you are the owner of a visual and believe we are using it without permission, please contact us —we will reply promptly and make things right. Featured Reviews Human Body, Vision, & The Brain Light, Eyes, & Vision 4-PS4-2, 4-LS1-1 Activity Prep In this lesson, students discover the basics of how their eyes work, and figure out some of the causes of vision problems. In the activity, Eye Model, students develop a working model of a human eye. They use a magnifying lens as a model of the cornea to explore how the structure of this lens is related to the function of our eyes. I have a Mystery Pack printout Print 30 copies 30 pairs 30 cards Try Making An Image With the Lens Before Class As soon as you have a 3X magnifying lens, use it to make an image. For the best image, you need a dimly lit room and an interesting light source — like a window that lets light in, a lamp with a shade, or a television. Watch this short video for a demonstration. After you’ve made an image, check to see what will work in your classroom. Do you have a door to the outside that you can prop open? A bright window? An interesting light fixture? If you have a large class, you can set up a few stations with lamps around the room, or send students in batches to a window. Hold On To The Eye Models If you will be teaching the next lesson "How can some animals see in the dark?" , then you must save the eye models that students make in this lesson. Keep them in a safe place until you are ready to teach the next lesson. Share this lesson Student link, google classroom, email parents, extend this lesson, discussions, mini-lessons, transcripts. How can we improve it? If you'd like our team to reply to you, please Contact Support instead. Thanks for your feedback! If you have a question or need help, please contact us . Please consider sharing your review: Sorry the lesson didn’t go well. We read every single review in an effort to improve our Mysteries. Thanks for letting us know. We’ll wait to ask you for feedback until after you've actually taught it. Thanks for the feedback! We read every single review in an effort to improve our Mysteries. Is the video not playing properly? Very rarely a video will fail to completely load in your browser. Try to reload this page to see if that fixes the problem. If reloading does not help, try our other video player . 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Chrome (recommended) Microsoft Edge WATCH: Olympic shooting glasses, explained "closing our one eye for a couple hours at a time becomes really painful and tedious," lexi lagan said. "having that little blinder allows us to keep both eyes open but still focus on what we're doing.", by nicole tan • published july 31, 2024 • updated on july 31, 2024 at 5:56 pm. Interest surrounding Olympic shooting took off when photos of South Korean sharpshooter Kim Yeji circulated on the internet. Her stone-cold and unbothered demeanor was accented by her shooting glasses, seemingly taken right out of a sci-fi movie. But the glasses aren't just for style points. Philadelphia news 24/7: Watch NBC10 free wherever you are "We typically want to have a blinder on one side, and the other side can either be a prescription lens for your glasses ... [or] a colored lens, depending on what the environment is like when we're shooting," Team USA air pistol athlete Lexi Lagan said. Specifically, the blinder is crucial for pistol shooters who are aiming long distances with no magnification . 329 medal events. 32 sports. Endless drama. Catch all the action at the Paris Olympics . Sign up for our free Olympics Headlines newsletter. "Closing our one eye for a couple hours at a time becomes really painful and tedious," Lagan said. "Having that little blinder allows us to keep both eyes open but still focus on what we're doing." This way, shooters can pick and choose what factor to focus on, whether it is the target, their front sight or their rear sight. Lagan said she got so used to the glasses that she once walked to a college class with her glasses still on. This article tagged under: What are Phryges? Everything to know about the Paris 2024 mascot The mascot of the Paris Olympic Games may not seem all that mighty to those outside the host country, but that little red hat, known as a Phrygian cap (or a liberty cap), is a symbol of the French liberation. The Phryges (pronounced "FREE-jes") were announced as the mascots of the Paris Games in November 2022. Paris 2024 said the caps are "sporty, love to party ... and are so French." But the little red caps — one each for the Olympics and the Paralympics — have so much more to them than meets the eye. Follow live updates on the 2024 Olympics "We chose the Phrygian cap because it’s a very strong symbol for the French Republic," Tony Estanguet, president of the Paris 2024 organizing committee, said when the mascots were revealed . "For French people, it’s a very well-known object that is a symbol of freedom, an object that will represent mascots all across the world. The fact that the Paralympics mascot has a visible disability also sends a strong message: to promote inclusion." Estanguet added the caps are on "a mission of revolution through sport." When French revolutionaries stormed the Bastille prison in July 1789, kicking off the French Revolution, they wore the caps, which have since been known as a symbol of liberty and the revolution. Even today, protesters will don the caps as they march. The Phrygian cap was worn during many French historical moments aside from the revolution, such as the constructions of the Notre-Dame de Paris cathedral and the Eiffel Tower, and at the 1924 Olympic Games in Paris. Today, the Phrygian caps can be seen in every town hall and on French coins and stamps. The Paris 2024 Phryges are blue, white and red — the colors of the French flag — and feature a gold "Paris 2024" logo on their chests. Their eyes are made out of a "cockade of France," or a knot of ribbons that is the French national ornament, according to Olympics.com. France has a rich history when it comes to Olympic mascots. The first, Shuss , was unveiled for the 1968 Winter Games in Grenoble, according to NBC Olympics. Mascots on a mission of inclusivity Organizers of the Paris Games called out the Phryges' mission of inclusivity. "We chose an ideal rather than an animal," Estanguet said, according to Olympics.com. Organizers have described the mascots for the Olympic and Paralympic Games as belonging to a larger family of Phryges. "They are the two main characters in a large tribe; they’re part of the family of Phryges," Paris 2024 brand director Julie Matikhine said, according to Olympics.com. "According to our narrative, they have existed for thousands of years and were present during several key events in French history." She continued: "Now they have returned for this big event in France to lead a mission of revolution through sport. The aim is to show that sport can change everything in society. The objective is to show that sport and its values can do great things. It’s about fraternity, solidarity and it helps society grow." The Olympic Phryge "is a tactician with a calculating, mathematical brain. Its methodical mind and alluring charm are sure to inspire people to get involved with sport," while the Paralympic Phryge, identifiable by its prosthesis and racing blade, "is spontaneous and full of energy and enthusiasm," according to NBC Olympics . Their joint motto is: "Alone we go faster, but together we go further." Rebecca Cohen is a breaking news reporter for NBC News. Skip to main content Keyboard shortcuts for audio player The Indicator from Planet Money LISTEN & FOLLOW Apple Podcasts Amazon Music Amazon Alexa Your support helps make our show possible and unlocks access to our sponsor-free feed. Getting more men into so-called pink-collar jobs Darian Woods Wailin Wong Angel Carreras Paddy Hirsch Jobs numbers came out today and they weren't great: Unemployment hit 4.3% and only 114,000 jobs were added to the economy in July. The U.S. economy's downshifting gears ... but there are bright spots. Care jobs grew. Like social assistance: 9,000 new jobs in July. Social work organizations have been calling out for more men in particular ... and with unemployment rising for men, a lot of them want jobs. So why aren't they meeting? Today on the show: Getting more men into so-called pink-collar jobs. We learn about an experiment that showed a surprising way to encourage men into industries traditionally represented by women. Related Episodes: Wanted: Social workers Ghost jobs For sponsor-free episodes of The Indicator from Planet Money, subscribe to Planet Money+ via Apple Podcasts or at plus.npr.org . Music by Drop Electric . Find us: TikTok , Instagram , Facebook , Newsletter . jobs report social workers Jobs Friday pink collar jobs Olympics 2024 Stephen Nedoroscik Wears Glasses Due to Strabismus. Here’s What That Is O lympian Stephen Nedoroscik—a.k.a. “ The Pommel Horse guy ”—introduced Americans to more than just a niche sporting event when he helped the U.S. men’s gymnastics team clinch a bronze medal on July 29. He also raised awareness for an eye condition called strabismus, the apparent reason for the now-viral glasses he wears while waiting for his turn to compete, and which he hoisted in the air while celebrating with his team. Dr. William Flanary, an ophthalmologist with EyeHealth Northwest in Oregon—best known for the satirical videos he posts as his comedic alter-ego, Dr. Glaucomflecken— posted on X that Nedoroscik’s fame is “possibly the greatest moment for glasses in Olympic history.” “Just seeing someone like him on such a huge stage, winning an Olympic medal and unabashedly wearing his glasses…does a lot for making it normal,” Flanary tells TIME. Here’s what to know about strabismus. What is strabismus? Strabismus is the medical term for being cross-eyed, or having eyes that point in different directions. Typically, the brain sorts through information transmitted by each eye to create a cohesive visual picture and assess distance and depth. When there’s misalignment between the eyes, as with strabismus, “you can actually see two images” instead of one, explains Dr. Dean Cestari, director of adult strabismus care at Massachusetts Eye and Ear. This often leads to sight issues like double vision, blurry vision, and light sensitivity, Cestari says. Nedoroscik recently told Today that his vision is not clear without his glasses. He has also posted on TikTok about having light sensitivity. Read More : What Olympic Athletes Eat to Have All That Energy For some people with strabismus, one eye is always the one to turn in, out, up, or down. In other people, however, the turned eye can alternate, according to the American Optometric Association (AOA). The latter is the case for Nedoroscik, who has posted on TikTok about his ability to “switch [his] dominant eye,” a skill that he said at the time he could find little information about. (Note to Nedoroscik: Flanary says this ability is fairly common among people with strabismus and is known as “alternating fixation.”)  More From TIME What causes strabismus. Babies can be born with strabismus or it can develop later in life. Overall, an estimated 2% to 5% of the population has strabismus. Strabismus can occur due to problems with the muscles and nerves that control the eyes, as a side effect of an eye injury or other medical condition, or as a complication from significant far-sightedness, the AOA says. It can also run in families. An estimated 30% of children with strabismus have a family member with a similar diagnosis, the Cleveland Clinic says . a really, really special moment as @GymnastSteve got to meet (and give pins to) a young fan with the same eye condition as him 🫶 pic.twitter.com/cM8LEVz0vx — USA Gymnastics (@USAGym) July 30, 2024 Nedoroscik has also posted about having coloboma, a condition that leads to missing eye tissue . “Colomba can cause decreased vision or blurry vision, but it can also cause an elongation of the eyeball. Depending on how elongated the eye is, that can result in a strabismus,” Cestari explains. How is strabismus treated? The earlier strabismus is treated, the better, Flanary says. Kids with untreated strabismus will often learn to “basically turn off vision in [their turned] eye and ignore that eye,” Flanary explains. Over time, that coping mechanism can lead to long-term vision problems in the turned eye, or what is colloquially known as a lazy eye. That said, it’s never too late to treat strabismus, says Cestari, who specializes in treating adults. “The most common sentence I hear is, ‘Oh my God, I didn’t know this could be fixed as an adult,’” he says. “It’s absolutely not true” that only kids can be treated. Read More : How Much Hair Loss Is Normal for Women? Depending on the person and the details of their case, a pair of glasses in the right prescription may be all that’s necessary to straighten vision and address strabismus, Flanary says. But in some cases, according to the Cleveland Clinic, people may also need eye exercises, surgery, medications, or “patching”—purposely covering one eye to strengthen the other. Nedoroscik’s glasses have become his much-memed trademark during the Olympics, although he doesn’t wear them when he’s competing. “When I go up on the pommel horse, it’s all about feeling the equipment,” he told Today. I don’t even really see when I’m doing my gymnastics. It’s all in the hands—I can feel everything.” More Must-Reads from TIME The Rise of a New Kind of Parenting Guru The 50 Best Romance Novels to Read Right Now Mark Kelly and the History of Astronauts Making the Jump to Politics The Young Women Challenging Iran’s Regime How to Be More Spontaneous As a Busy Adult Can Food Really Change Your Hormones? Column: Why Watching Simone Biles Makes Me Cry Get Our Paris Olympics Newsletter in Your Inbox Write to Jamie Ducharme at [email protected] Election 2024 Entertainment Newsletters Photography AP Buyline Personal Finance AP Buyline Shopping Press Releases Israel-Hamas War Russia-Ukraine War Global elections Asia Pacific Latin America Middle East Delegate Tracker AP & Elections 2024 Paris Olympic Games Auto Racing Movie reviews Book reviews Financial Markets Business Highlights Financial wellness Artificial Intelligence Social Media Blood tests for Alzheimer’s may be coming to your doctor’s office. Here’s what to know FILE - A doctor points to PET scan results that are part of a study on Alzheimer’s disease at Georgetown University Hospital, on Tuesday, May 19, 2015, in Washington. (AP Photo/Evan Vucci, File) Copy Link copied WASHINGTON (AP) — New blood tests could help doctors diagnose Alzheimer’s disease faster and more accurately, researchers reported Sunday – but some appear to work far better than others. It’s tricky to tell if memory problems are caused by Alzheimer’s. That requires confirming one of the disease’s hallmark signs — buildup of a sticky protein called beta-amyloid — with a hard-to-get brain scan or uncomfortable spinal tap. Many patients instead are diagnosed based on symptoms and cognitive exams. Labs have begun offering a variety of tests that can detect certain signs of Alzheimer’s in blood. Scientists are excited by their potential but the tests aren’t widely used yet because there’s little data to guide doctors about which kind to order and when. The U.S. Food and Drug Administration hasn’t formally approved any of them and there’s little insurance coverage. “What tests can we trust?” asked Dr. Suzanne Schindler, a neurologist at Washington University in St. Louis who’s part of a research project examining that. While some are very accurate, “other tests are not much better than a flip of a coin.” Demand for earlier Alzheimer’s diagnosis is increasing More than 6 million people in the United States and millions more around the world have Alzheimer’s, the most common form of dementia. Its telltale “biomarkers” are brain-clogging amyloid plaques and abnormal tau protein that leads to neuron-killing tangles. This article is part of AP’s Be Well coverage, focusing on wellness, fitness, diet and mental health. Read more Be Well. New drugs, Leqembi and Kisunla, can modestly slow worsening symptoms by removing gunky amyloid from the brain. But they only work in the earliest stages of Alzheimer’s and proving patients qualify in time can be difficult. Measuring amyloid in spinal fluid is invasive. A special PET scan to spot plaques is costly and getting an appointment can take months. Even specialists can struggle to tell if Alzheimer’s or something else is to blame for a patient’s symptoms. “I have patients not infrequently who I am convinced have Alzheimer’s disease and I do testing and it’s negative,” Schindler said. New study suggests blood tests for Alzheimer’s can be simpler and faster Blood tests so far have been used mostly in carefully controlled research settings. But a new study of about 1,200 patients in Sweden shows they also can work in the real-world bustle of doctors’ offices — especially primary care doctors who see far more people with memory problems than specialists but have fewer tools to evaluate them. In the study, patients who visited either a primary care doctor or a specialist for memory complaints got an initial diagnosis using traditional exams, gave blood for testing and were sent for a confirmatory spinal tap or brain scan. Blood testing was far more accurate, Lund University researchers reported Sunday at the Alzheimer’s Association International Conference in Philadelphia. The primary care doctors’ initial diagnosis was 61% accurate and the specialists’ 73% — but the blood test was 91% accurate, according to the findings, which also were published in the Journal of the American Medical Association. Which blood tests for Alzheimer’s work best? There’s almost “a wild West” in the variety being offered, said Dr. John Hsiao of the National Institute on Aging. They measure different biomarkers, in different ways. Doctors and researchers should only use blood tests proven to have a greater than 90% accuracy rate, said Alzheimer’s Association chief science officer Maria Carrillo. Today’s tests most likely to meet that benchmark measure what’s called p-tau217, Carrillo and Hsiao agreed. Schindler helped lead an unusual direct comparison of several kinds of blood tests, funded by the Foundation for the National Institutes of Health, that came to the same conclusion. That type of test measures a form of tau that correlates with how much plaque buildup someone has, Schindler explained. A high level signals a strong likelihood the person has Alzheimer’s while a low level indicates that’s probably not the cause of memory loss. Several companies are developing p-tau217 tests including ALZpath Inc., Roche, Eli Lilly and C2N Diagnostics, which supplied the version used in the Swedish study. Who should use blood tests for Alzheimer’s? Only doctors can order them from labs. The Alzheimer’s Association is working on guidelines and several companies plan to seek FDA approval, which would clarify proper use. For now, Carrillo said doctors should use blood testing only in people with memory problems, after checking the accuracy of the type they order. Especially for primary care physicians, “it really has great potential to help them in sorting out who to give a reassuring message and who to send on to memory specialists,” said Dr. Sebastian Palmqvist of Lund University, who led the Swedish study with Lund’s Dr. Oskar Hansson. The tests aren’t yet for people who don’t have symptoms but worry about Alzheimer’s in the family — unless it’s part of enrollment in research studies, Schindler stressed. That’s partly because amyloid buildup can begin two decades before the first sign of memory problems, and so far there are no preventive steps other than basic advice to eat healthy, exercise and get enough sleep. But there are studies underway testing possible therapies for people at high risk of Alzheimer’s, and some include blood testing. The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Educational Media Group. The AP is solely responsible for all content. Revisiting the Heider and Simmel experiment for social meaning attribution in virtual reality Marañes, Carlos Gutierrez, Diego Serrano, Ana In their seminal experiment in 1944, Heider and Simmel revealed that humans have a pronounced tendency to impose narrative meaning even in the presence of simple animations of geometric shapes. Despite the shapes having no discernible features or emotions, participants attributed strong social context, meaningful interactions, and even emotions to them. This experiment, run on traditional 2D displays has since had a significant impact on fields ranging from psychology to narrative storytelling. Virtual Reality (VR), on the other hand, offers a significantly new viewing paradigm, a fundamentally different type of experience with the potential to enhance presence, engagement and immersion. In this work, we explore and analyze to what extent the findings of the original experiment by Heider and Simmel carry over into a VR setting. We replicate such experiment in both traditional 2D displays and with a head mounted display (HMD) in VR, and use both subjective (questionnaire-based) and objective (eye-tracking) metrics to record the observers' visual behavior. We perform a thorough analysis of this data, and propose novel metrics for assessing the observers' visual behavior. Our questionnaire-based results suggest that participants who viewed the animation through a VR headset developed stronger emotional connections with the geometric shapes than those who viewed it on a traditional 2D screen. Additionally, the analysis of our eye-tracking data indicates that participants who watched the animation in VR exhibited fewer shifts in gaze, suggesting greater engagement with the action. However, we did not find evidence of differences in how subjects perceived the roles of the shapes, with both groups interpreting the animation's plot at the same level of accuracy. Our findings may have important implications for future psychological research using VR, especially regarding our understanding of social cognition and emotions. No Sources Found 232 COMMENTS How Vision Works: Eye Science Projects & Experiments The human eye is one of the the most complex and sophisticated sensory organs in the body. Its unique automatic focusing system outstrips that of any camera, and its light sensitivity is ten million times greater than the best film designed so far! Before taking a look at how the eye works, let's start with a basic overview of how it is built. Amazing Vision Eye Science Experiments for Kids Eye Science Experiments. Children will have fun learning about how their eyes work with this easy science project exploring their sense of sight! This Eye Science Experiments is such a fun addition to a lesson on my body for preschoolers, kindergartners, grade 1, grade 2, grade 3, grade 4, grade 5, and grade 6 students. Plus you will appreciate ... How Does An Eye Work Human Body Experiment In this fun and easy science experiment, we're going to explore and investigate the human body and how eyes work. Materials: Wax paper Safety pin Paper cup Rubber band Instructions: Using the safety pin, poke a small hole in the center of the bottom of the paper cup. Place a piece of the wax paper over the mouth of the cup. Use the rubber band to hold the wax paper in place. Point the bottom ... How the Human Eye Works Now that you know the names of the parts of the eye, it's easy to follow the steps leading to vision. Cornea: Light enters the eye through the cornea. Because of the shape of the cornea, it exits pre-focused. Aqueous Humor/Pupil: From the cornea, light passes through the aqueous humor and through the pupil. Easy science experiment to show how the eye works Here's an easy experiment for kids to show how the eye works How the Eye Works Jared tells us how light passes through the lens of our eye and places an upside down image on the back of the eyeball. Our amazing brain then flips the imag... How Do Our Eyes Work? Lab Experiment Subscribe for more crazy, fun and exciting science facts: https://goo.gl/4XwBh1Ever wondered how we can see? Dr Chris and Dr Xand of Operation Ouch are learn... PDF Vision: How does your eye work? Have someone hold the tester 500 mm (0.5 m or 50 cm) in front of your eye (place the + between your eyes, with the paper extending to the left). Close your right eye and look at the + with your left eye. Place a pencil eraser or bright object on the far left side of the tester. Slowly move the pencil eraser to the right. Experiment: How Your Eye Detects Color and Motion Experiment Steps. The test subject holds the poster board in front of them while bending it around their face, so that the ends meet their ears and rests about a foot away from their face. Your eyes should be level with the fixation point as well. The test subject now focuses on the black dot in front of them. How the eye focuses light The eye focuses light in a similar way to when you use a magnifying glass to concentrate the Sun's rays onto a piece of paper. The distance from the magnifying lens to the piece of paper is the focal length. For the eye, light from distant objects is focused onto the retina at the back of the eye. The eye is about the size of a table tennis ... How the eye works The eye has actually only got two receptors - you've got rods and you've got cones. We'll dismiss the rods straight away, because all they do is provide you with your peripheral vision. They will detect movement, and they're actually black and white, so not able to detect colour. In the centre, you've got the cones, and the cones ... PDF Vision: How does your eye work? 3. Have someone hold the tester 500 mm (0.5 m or 50 cm) in front of your eye (place the + between your eyes, with the paper extending to the left). 4. Close your right eye and look at the + with your left eye. 5. Place a pencil eraser or bright object on the far left side of the tester. 6. Slowly move the pencil eraser to the right. 7. How the Eyes Work 5:09 · Human Body. Despite its small size, the eye is a complex machine that feeds data to the brain at lightning speed. Light enters the eye through the cornea and passes through the pupil to the lens. The lens focuses the rays onto the retina, but images on the retina are upside down, reversed, and two-dimensional. Human Eye Science Project Ideas Anatomy of the Eye. The eye is an organ with highly specialized cells that work both individually and together to form vision. Students can research the shape of the eye and information about how each part contributes to vision. They can experiment to see what happens if one of the steps in vision changes, such as altering the shape of the lens. Neuroscience for Kids Figure 1. The electromagnetic spectrum and the visible spectrum. 2. The eyeball is an optical device for focusing light. The mammalian eyeball (Figure 2) is an organ that focuses a visual scene onto a sheet of specialized neural tissue, the retina, which lines the back of the eye. Light from a scene passes through the cornea, pupil, and lens on ... PDF Lesson 3 Hold the ruler in front of your nose a little. Hold the paper at the end of the ruler so that the cross is on the right hand side. Keep your right eye closed or covered and look at the paper with ... Simple Science Experiment: How Our Eyes Perceive Color There's nothing like the beautiful colors of summer to make us really appreciate our vision. This month's simple science experiment is a cool way to show how your eye works in its perception of colors! Materials: A drawing of an object (a star, a heart, etc) that has a yellow border, a green interior, and a black dot in the center. How the eye works How the eye works. Rating: 3.4 /5. From 467 votes. Voting is currently disabled, data maintenance in progress. Sense of Sight October 5, 2018. 3 min read. by ItsySparks. Mini Scientists. In studying about our Fives Senses, we have enjoyed exploring our sense of touch, hearing, and taste. Our most recent exploration has been with our sense of sight. We rely very much on our sight to move around and see things every day. Our eyes are very complex in how they work. How the Eye Works Animation The eye is the organ of sight and is shaped as a slightly irregular hollow sphere. Various structures in the eye enable it to translate light into recognizab... Optics of the Human Eye Optics of the Human Eye. Description. This is a simulation demonstrating the optics of the human eye. It also shows how various lenses can be used to correct for faulty vision. Be aware that it is a simplified version of what actually happens. In the simulation, there is no bending when light moves from the air into the eye (when most of the ... What do people who are blind see? the back of the eye that senses light and sends messages to the brain. a clear object that changes the direction of light as it passes through. a test used to discover new information about a question. a pretend version of something that scientists use when the real thing is too big, small, or complicated to work with. Olympic shooting glasses, explained "Closing our one eye for a couple hours at a time becomes really painful and tedious," Lexi Lagan said. "Having that little blinder allows us to keep both eyes open but still focus on what we're ... What are Phryges? Everything to know about the Paris 2024 mascot The Paris 2024 Phryges are blue, white and red — the colors of the French flag — and feature a gold "Paris 2024" logo on their chests. Their eyes are made out of a "cockade of France," or a ... Social work organizations have been calling out for more men : The Social work organizations have been calling out for more men : The Indicator from Planet Money Jobs numbers came out today and they weren't great: Unemployment hit 4.3% and only 114,000 jobs were ... Here's Why Stephen Nedoroscik Wears Glasses Strabismus can occur due to problems with the muscles and nerves that control the eyes, as a side effect of an eye injury or other medical condition, or as a complication from significant far ... New blood tests could diagnose Alzheimer's. Here's what to know WASHINGTON (AP) — New blood tests could help doctors diagnose Alzheimer's disease faster and more accurately, researchers reported Sunday - but some appear to work far better than others.. It's tricky to tell if memory problems are caused by Alzheimer's. That requires confirming one of the disease's hallmark signs — buildup of a sticky protein called beta-amyloid — with a hard ... Body Parts Operation Ouch is a science show for kids that is full of experiments and biological learnings. In this educational TV show, twin brothers Dr. Chris and Dr. ... Revisiting the Heider and Simmel experiment for social meaning In this work, we explore and analyze to what extent the findings of the original experiment by Heider and Simmel carry over into a VR setting. We replicate such experiment in both traditional 2D displays and with a head mounted display (HMD) in VR, and use both subjective (questionnaire-based) and objective (eye-tracking) metrics to record the ... Olympic water polo star Ashleigh Johnson's skin and hair routine The final but perhaps most essential step in any swimmers' hair- and skin care routine, Johnson says, is to experiment and innovate, shedding those steps or products that don't seem to work ... essay homework paper phd review speech study thesis