THE EYE
CHAPTER 8
PAGES 272-284
COLOR CODE – PLATE 137
Sclera – orange
fovea centralis – light green
Cornea – green
optic disc - tan
Choroid – brown
posterior chamber - peach
Iris – blue
Retina – purple
Vitreous body – light blue
Aqueous humor – yellow
Lens – gray
Pupil – black
Conjunctiva – pink
Optic nerve - red
COLOR CODE – PLATE 139
Superior rectus – red
Inferior rectus – pink
Lateral rectus – blue
Medial rectus – light blue
Superior oblique – green
Inferior oblique – light green
Ciliary – orange
Sphincter pupillae – yellow
Dilator pupillae – peach
Visual object – aqua
Light waves - gray
Retina – purple
Optic nerve – brown
Visual cortex - tan
I. PARTS OF THE EYE (page 275/276)
Sclerotic layer (sclera)
1. white, tough, outer layer
2. functions: provides shape of eyeball
protection
B. Choroid layer
1. contains blood vessels
2. function: nourishing eyeball
A.
C. Retina
1. inner layer
2. contains specialized cells that
function in forming the image
a. rods – sensitive to dim light
form a shaded image
b. cones – sensitive to bright light
responsible for color vision
D. Fovea
1. focal point of the retina
2. vision is clearest at this point
3. where cones are > #ous
E. Optic Nerve
1. connects eyeball to brain
2. carries nerve messages to/from the brain
3. controls vision
F. Blind Spot (pg.277)
1. where optic nerve joins the eyeball
2. where retina lacks rods & cones
3. no vision @ this point
G. Cornea
1. clear bulge of the sclerotic layer
2. in front portion of eyeball
3. clear, to allow passage of light rays
H. Iris
1. colored portion of eyeball
2. posterior to cornea
3. regulates the amt. of light entering the eye
I. Pupil
1. opening in the iris
2. allows light to pass on to the retina
3. changes shape to optimize amt. of light
a. dilates – gets larger in dim light
b. constricts – gets smaller in bright light
4. must adjust when changing from dim to
bright light and vise-versa
J. Lens (pg. 280)
1. a convex, crystalline (glassy) structure
2. posterior to the pupil & iris
3. focuses light rays on the retina
4. changes thickness when focusing close vs.
@ a distance
K. Ligaments
1. attaches lens to muscles wh/ support the lens
2. regulates the shape of the lens from thin to
flat in order to view objects close & @ a
distance
L. Aqueous humor
1. H2O-y fluid b/t cornea & iris
2. helps to maintain shape of cornea
M. Vitreous humor
1. jelly-like substance in the inner part of
the eyeball
2. maintains shape of the entire eyeball
N. Lacrimal glands
1. located on the inner lining of the
eyeball
2. secretes tear fluid wh/ moisten &
washes the eyeball
O. Eyelids
protect & moisten eyeball
P. Conjunctiva
1. lines the eyelids & covers part of outer
surface of the eyeball
2. secretes mucus wh/ helps to lubricate
eyeball & keep it moist
II. Diseases/Conditions . . . . . . . .
A. color blindness
1. lack of 1 or more types of cones
2. lack of 1 type  partial color blindness
3. lack of all 3 types  total color bldnss.
4. sex-linked trait  almost exclusively in
males
B. conjunctivitis
1. commonly called pinkeye
2. inflammation of the conjunctiva
3. causes red, irritated, itchy eyes
4. highly contagious (bacterial/viral)
C. cataracts
1. lens b/c hard & opaque
2. causes vision to be hazy  blindness
3. treatments:
a. surgical removal of lens &
replacement w/ lens implant
b. special cataract glasses
c. laser surgery to remove hardened
area of lens
D. Glaucoma
1. pressure w/i the eye increases dramatically
due to blocked drainage of aqueous humor
2. compresses retina & optic nerve
3. causes pain & possible blindness
4. symptoms:
a. seeing halos around lights
b. headaches
c. blurred vision
5. treatments:
a. eyedrops wh/ increase drainage rate
b. surgical enlargement of drainage channel