1. Unit 2 Notes: Vision

2. (1) Outer Layers of The Eye
3 layers surrounding inner fluid:
Outermost = Sclera
Middle Tissue = Choroid
Innermost = Retina
Inner Fluid = Humor
Humor increases inner pressure
Maintains eyeball shape
Glaucoma  Increase in Pressure

4. (2) The Sclera White tissue on the outside Contains the cornea:
Light enters the eye here
Directly connected to nerve endings

5. (3) The Choroid Made of darker pigments:
Keeps light rays inside the eye
Contains the ciliary body and the iris:
Ciliary Body = Lens is attached to this Tissue
Iris = Pigmented portion of your eye
Muscle
Contract = Decrease Light Inflow
Relax = Increase Light Inflow

6. (4) The Retina Contains Photoreceptors (Rods & Cones)
Electrical signal passes from receptors  optic nerve  brain
Rods = Shades & Grays
Cones = Colors
Blue-Yellow
Green
Red-Green
Impulses from multiple receptors  In Between Colors

9. (5) Color Blindness Monochromacy Dichromacy
All cones are missing or damaged
No color
Still can see shades (rods function)
Dichromacy
Red-Green Colors look the same
Blue-Yellow Colors look the same

11. (6) Light Refraction & The Lens
Light passes through the cornea and Lens to enter eyeball…
Light passing thru different mediums  Refraction
Refraction = Bending of light
Eye controls amount of light entering with Iris + Lens:
Ciliary Body Contraction  Closing In of Iris  Decreased Pupil Size
Ciliary Body Relaxes  Widening of Iris  Increased Pupil Size

13. (7) Types of Eyesight Emmetropia = Perfect Eye Sight
Myopia = Nearsighted
Hyperopia = Farsighted
Astigmatism = All Messed Up 

14. (8) Myopia Cornea too convex or bulging… Solution:
Light is over focused and refracted before hitting retina
Light rays are scattered when hitting retina
Blurred Vision
Solution:
Concave Lens (thinner in middle)
Decreases refraction, Spreads out Light Rays

16. (9) Hyperopia Cornea is too concave (flattened out): Solution:
Light is not focused or refracted enough
Light rays are scattered when hitting retina
Blurred Vision
Solution:
Convex Lens (thicker in middle)
Refracts and Focuses light before hitting eye

18. (10) Astigmatism Uneven cornea or lens: Solution:
Causes blurred vision because light is refracted unevenly
Astigma = Not A Point
Solution:
Concave + Convex Lens
Cancels out Uneveness

21. EYEBALLS!!!