1. The Eye
Chapter 8

2. Sclera
Thick, white tissue that covers the outermost part of the eyeball
The “white of the eye”
Central, anterior portion is clear

3. Cornea Transparent window through which light enters the eye
Did you know…
The cornea is the only tissue in the body that can be transplanted without the worry of rejection
Since no blood vessels can reach the cornea, it is out of the reach of the immune system

4. Choroid Middle coat of the eyeball
Prevents light from scattering inside the eye

5. Iris Band of muscles that control the size of your pupil
Pigment in iris determines the color of your eyes
Did you know…
People with blue eyes have the least amount of pigment in their iris
People with brown eyes have the most pigment in their iris

6. Pupil
Opening in the iris that regulates the amount of light that passes into the eye
Constricts: close vision & bright light
Dilates: far vision & dim light

7. Lens Focuses light entering the eye on the retina Cataracts:
Lens gets hard and opaque causing it to not be able to focus light as well resulting in hazy vision and eventually blindness

8. Nearsighted vs. Farsighted
Lens doesn’t focus light correctly on retina
Nearsighted (myopia)
Distance objects appear blurry
Point of focus before retina
Farsighted
Near objects appear blurry
Point of focus behind retina

9. Retina Innermost layer
Contains photoreceptor cells that respond to light
Rods
cones

10. Photoreceptors Rods Cones Allow us to see gray tones
Provide for peripheral vision
Cones
3 varieties (red, green, blue)
Allow us to see colors
Color blindness: caused by lack of cone type
Did you know…
Colorblindness is more frequent in men than women…it is a sex linked trait

11. Optic Nerve
Photoreceptors transfer message they receive from light to the optic nerve
Optic nerve sends message to brain
Result is vision.
Blind spot:
Location where optic nerve leaves eyeball (optic disk)
no photoreceptors

12. Aqueous Humor Anterior to the lens clear watery fluid
Helps maintain pressure inside the eye so it doesn’t collapse inward
Glaucoma: aqueous humor is blocked from draining and increases the pressure in the eye and compresses the retina and optic nerve

13. Vitreous Humor Posterior to the lens Gel like
Helps maintain pressure inside the eye so it doesn’t collapse inward