1. How your eyes work and the structures that allow us to see
The Eye
How your eyes work and the structures that allow us to see

2. The Eye
Our eyes give us insight to the world around us.
Our eyes bring in the light that is present and see the reflected colors and create images in our brains
Our eyes our the organs of our visual system

3. The Eye The eye is almost totally spherical in shape
Our eye allows us to see in stereo vision (3D)
Our eyes take light and transmit the light to electrical impulses for us to see images.

4. The Eye
How we see:
First, light passes through the cornea of the eye. The cornea is a clear, protective covering on the outside of the eye.
Next, light passes through the pupil. The pupil is a black opening in the eye that lets light enter the eye
The pupil is adjustable to allow different amounts of light in. It is controlled by muscles in the iris of the eye.
The iris gives us our eye color. This adjustment is called the iris reflex
Think/pair/share- give a real life example of your iris reflex

5. The Eye
How we see:
After passing into the eye through the pupil, light passes through the lens. The lens of the eye is a clear, curved structure. Along with the cornea, the lens helps focus light at the back of the eye.
The lens must bend light from nearby objects more than it bends light from far- away objects. The lens changes shape to bend the light by just the right amount to bring objects into focus.

6. The Eye
How we see:
The lens focuses light on the retina, which covers the back of the inside of the eye. The retina has light-sensing photoreceptor cells called rods and cones. Rods let us see in dim light. Cones let us detect light of different colors.
When light hits rods and cones, it causes chemical changes. The chemical changes start nerve impulses. The nerve impulses travel to the brain through the optic nerve.
The brain makes sense of the nerve impulses and tells you what you are seeing.

7. The Eye Parts of the eye:
Cornea: The cornea is the clear front surface of the eye. It lies directly in front of the iris and pupil, and it allows light to enter the eye.
Sclera: The sclera, along with the intraocular pressure (IOP) of the eye, maintains the shape of the eyeball.The tough, fibrous nature of the sclera also protects the eye from serious damage — such as laceration or rupture — from external trauma.The sclera also provides a sturdy attachment for the extraocular muscles that control the movement of the eyes.

8. The Eye Parts of the eye:
Lens: The lens is a transparent structure behind the iris, the coloured part of the eye. The lens bends light rays so that they form a clear image at the back of the eye – on the retina. As the lens is elastic, it can change shape, getting fatter to focus close objects and thinner for distant objects.
Iris: In addition to giving the eye its color, the iris acts like the diaphragm of a camera and controls the size of the pupil. One muscle within the iris constricts the pupil in bright light (full sunlight, for example), and another iris muscle dilates (enlarges) the pupil in dim lighting and in the dark.

9. The Eye Parts of the eye:
Pupil: The pupil is the opening in the center of the iris (the structure that gives our eyes their color). The function of the pupil is to allow light to enter the eye so it can be focused on the retina to begin the process of sight.
Retina: The retina is the sensory membrane that lines the inner surface of the back of the eyeball. It's composed of several layers, including one that contains specialized cells called photoreceptors. Photoreceptor cells take light focused by the cornea and lens and convert it into chemical and nervous signals which are transported to visual centers in the brain by way of the optic nerve.

10. The Eye Parts of the eye:
Optic Nerve: The job of the optic nerve is to transfer visual information from the retina to the vision centers of the brain via electrical impulses.
Aqueous Humour: The aqueous humour is a thin, transparent fluid similar to plasma. This fluid nourishes the cornea and the lens, and gives the eye its shape.
Vitreous Humour: The vitreous humor comprises a large portion of the eyeball. It is a clear gel-like substance that occupies the space behind the lens and in front of the retina at the back of the eye.

11. The Eye Parts of the eye:
Blindspot: Is a small portion of the visual field of each eye that corresponds to the position of the optic disk (also known as the optic nerve head) within the retina. There are no photoreceptors (i.e., rods or cones) in the optic disk, and, therefore, there is no image detection in this area.

12. The Eye Issues with vision
In the human eye, the lens cannot move, so the ciliary muscles change the shape of the lens (by making the lens bulge in the middle if the image comes closer to you and stretch if the object is further away).  This is done so that the eyeball isn't stretched. 
The process of changing the shape of the lens is called accommodation.

13. The Eye
Issues with vision
If an eye is too long, the image forms in front of the retina. This produces a condition called Myopia, or near- sightedness (distant objects are hard to see)
If an eye is too short, the image forms behind the retina. This produces a condition called Hyperopia, or far-sightedness (close objects are difficult to see)

14. The Eye
Animal eyes
Eyes that have a cornea, a lens and a retina are called camera eyes. Vertebrates (animals with backbones) for the most part have camera eyes.

15. The Eye
Fish have camera eyes with a perfectly round lens, which bulges
out from the pupil, allowing it to see in practically every direction.
Birds have sharper vision than humans because
they have five types of cones (humans have only 3),
each sensitive to different wavelengths of light.
The hawk's eye has many more cone cells than
the human eye and its vision is very sharp;
it is eight times sharper than human vision.
Nocturnal animals have eyes that collect as much light as possible because of their very large pupils. They also have a layer, called tapetum lucidum, inside their eye, which acts as a mirror. They also have many more rods than cones in their retina making their eyes more sensitive to low levels of light. Owls have large eyes that allow for excellent night vision.

16. The Eye
Insects and crustaceans have compound eyes. Each eye is made up of many smaller units called ommatidium. An ommatidium looks like a long tube with a lens on the outer surface, a focusing cone below it, and then a light sensitive cell below that. The compound eye is great for spotting movement, but with so many lenses it is difficult to form a single coherent image. Instead it forms a mosaic image (much like a tv screen).

17. The Eye
Types of eyes:

18. The Eye

19. The Eye https://visioneyeinstitute.com.au