1. The Eye

2. Anatomy of the Eye Sclera Choroid Retina Aqueous humor Iris
Blood vessels
Pupil
Cornea
Optic nerve
Lens
Blind spot
Ciliary muscle
Vitreous humor
Label the diagram of the eye!

3. Sclera and Cornea (outer layer)
Tough, white outer layer; Protects and
supports the eye
Tough, clear outer layer; Refracts (bends)
light toward
the pupil
Sclera

4. Choroid layer
Did you know that many nocturnal animals also have an iridescent layer of tissue called the tapetum lucidum which helps reflect light back into the eye?
Choroid
- A black layer within the eye that prevents light from scattering and provides the retina with nutrients.

5. Anatomy of the Eye - Iris
The coloured part of the eye
A muscle that contracts to control the size of the pupil; controls the amount of light entering the eye
Iris scans can be used as a method of identification because each person has unique banding of colour in their eye

6. Anatomy of the Eye - Pupil
The hole in the middle of the iris
Where light enters the eye
Size changes depending on the amount of light present in the environment

7. Anatomy of the Eye - Lens
Transparent structure behind the iris
Helps focus light rays onto the retina
Changes shape based on the distance of the object

8. Aqueous Humour and Vitreous Humour
- Jelly-like material at the front of the eye behind the cornea; supplies cornea with nutrients, bends light and maintains shape
Vitreous Humour
- Bends light and gives the eye structure
Iris scans – identification because each person’s iris has a different color pattern

9. Anatomy of the Eye - Retina
Nerve layer at the back of the eye
Senses light and creates nerve impulses
Location of the:
Rods: detect black and white
Cones: detect red, blue, & green

10. Rods and Cones Humans have 125 million rods and 6 million cones
Rods allow us to see black and white
Peripheral vision appears to be black and white because the cones are concentrated at the fovea

11. Color blindness Color blindness occurs when
one or more cones are defective
Red-green color blindness is most common
Caused by a genetic defect on the X chromosome
What numbers do you see?

12. Color blindness
How do we see colour?

13. Normal Vision Reduced sensitivity to blue

14. Normal Vision Reduced senitivity to red

15. Fovea centralis (macula)
Most sensitive area
of the retina,
highest
concentration of
CONES = greatest
visual acuity
To find the fovea,
draw a straight line
from the center of the lens

16. Anatomy of the Eye – Optic Nerve
Carries nerve signals from the retina to the brain, where the image is interpreted

17. Where the retina attaches to the optic nerve. There are
Blind Spot
Where the retina attaches to
the optic nerve. There are
NO rods or cones in the
blind spot
Hold text book 30 cm away. Close your right eye and look at the black cross with the left eye. Slowly move your left eye towards the figure and when the dot disappears, the image is falling on the blind spot.
You don’t notice the blind spot because one eye will compensate for the other.
Blind Spot
test!
Open to page 472
Optic nerve carries info to the occipital lobe

18. Ciliary Muscle Ciliary Body
Alters the shape of the lens; important in accommodation

19. Pink eye (conjunctivitis) =
Conjunctiva
Conjunctiva
Thin layer on top of the cornea for protecting the eye; blocks entry of pathogens into the eye
Pink eye (conjunctivitis) =
infection of the conjunctiva

20. Anatomy of the Eye – Eye Muscle
Helps to move the eye
Eye muscles operate in antagonistic pairs (ex: one muscle must relax and the other muscle contracts to move the eye)

21. Who do you see?

22. Who do you see?

23. Who do you see?

24. Optical Illusions!

25. Vision Problems and Corrective Lenses
Hyperopia – “Far sightedness”
Description: Person CAN see far objects; has difficulty seeing nearby objects
Solution: Glasses with converging lenses

26. Vision Problems and Corrective Lenses
Myopia – “Near sightedness”
Description: Person CAN see close objects; has difficulty seeing far objects
Solution: Glasses with diverging lenses

27. Presbyopia

28. Astigmatism
Irregularly shaped eye causes different focal lengths in the horizontal and vertical directions

29. Cataracts
Clouding of the lens leading to decreased vision and eventual blindness.