Transcript Eye Presentation - Downey Unified School District

Sage Lee, Samantha Alvarez
Layers of the Eye
 Outer layer
 Sclera
 Cornea
 Iris
 Lens
 Middle layer
 Uvea

Contains the blood vessels
 Inner layer
 Retina
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Rods
Cones
 Optic nerve
Fibrous Tunic
 The outer, fibrous
layer composed of the
sclera and the cornea
 The cornea: smooth,
clear glass-like
transparent region
made of loose
connective tissue that
protects the eye
Corneasclera
 The Sclera: the “white of the eye”, forming a
supporting wall for the eye
Vascular Pigmented Tunic
 The iris: circular muscle
that controls the size of the
pupil
 Ciliary body: responsible
for secretion of aqueous
humor
 Ciliary Muscle: responsible
for accommodating lens
Ciliary body and Choroid
 Choroid: layer of
blood vessels
providing
nutrients to the
retina
 Pupil: controls
amount of light
entering the eye
 Lens: a structure
that helps focus
light on the retina
The nervous tunic
 The retinas major regions
consists of;
 Optic papilla: joint of optic
nerve and retina
 Fovea centralis with macula
lutea: area of greatest visual
acuity
 Pigment Epithelium
Cells of the eye
 Photoreceptors
 Neurons: Bipolar,
Ganglion cells,
Centrifugal cells, and
amocrine
 Supporting cells:
Muller’s cells and
Neurological cells
 Cones
Eye glands
 Meibomian glands
 Lacrimal Gland
Components of Retina
 9 layers:
 Layer of
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rods and
cones
Optic
Nerve
Fovea
Macula
Ganglion
Layer
Eye Muscles
 Inferior oblique muscle
 Inferior rectus muscle
 Lateral recuts muscle
 Medial rectus muscle
 Superior rectus muscle
 Superior oblique muscle
 Levator palpeprae muscle
Eye Secretions
 Vitreous
 Drusen
 Aqueous Humor
Neurons and Visual Process
 Photoreceptors
 Rods
 Cones
 Bipolar Neuron
 Amacrine Cells
 Ganglion Cells
 Optic Nerve
Bipolar Neuron
 Axon extends from one side, dendrite from the other
 Found also in the nose and ear
 Used for sense of smell and hearing
 Form in middle layer of the retina
Amacrine Cells
 Located at the inner
plexiform of the retina
(IPL)
 Transfer message
between bipolar cells
and ganglion cells
 Classified into two types
 By dendrite morphology
and stratification
(formation and
appearance)
Ganglion Cells and Optic Nerve
 Ganglion cells
 Transmit the message to
the optic nerve
 Optic nerve
 Longest part of process
 Reaches a far part in the
brain where the image is
processed


Processing is done in the
lateral geniculate body
Output is sent to the striate
cortex so we can see the
“picture”
Visual Receptors
Rods
Cones
 Location: retina
 Location: retina
 Thin projection at terminal
 Short, blunt projections
ends
 Approx. 100 million
 More sensitive to light
 Nerve fibers converge causing
blurry outlines
 3 different kinds to detect
color
 Red, blue, green
 Approx. 3 million
 Single fibers, no convergence.
Create sharp images
Visual Receptors Cont.
 Vision and the receptors only stimulated by light
 Each receptor sends a small portion of the big picture
to the brain
 The brain puts it all together
 Epithelial pigment absorbs light not taken in by
receptors


Epithelial pigment and pigment of choroid coat keep light
from reflecting off of surfaces in the eye
Pigment layer stores vitamin A
 Helps receptor cells to synthesize visual pigments
Interpreting Sight
● Refraction
○ occurrs when light rays travel
through through the curved, clear
front surface of the eye(cornea).
● Convergent vs. Divergent waves
○ Converging waves: light waves that
come together from different
directions and have a common
meeting point on the lens of the eye.
○ Divergent wave: light waves that
come from different directions, and
once it hits the lens, continues to
travel in different directions.
Interpreting Sight Cont.
● Convergent vs. divergent lenses
● Converging lens(convex)
● directs rays of light to a point at the optical center or axis of the lens
● thick across the middle and thin at the upper and lower edges
● Diverging lens(concave)
● directs light away from the optical center or
axis of the lens
● thin across middle and thick at the upper and lower edges
Interpreting Sight Cont.
● Dark vs. Light vision
○ Pupil expands and contracts
depending on the amount of
light, and could physically block
out light form the eye
○ Cone cells can perceive color in
bright light.
○ Rod cells perceive black and
white images and work best in
low light.
■ contains Rhodopsin
● it is the chemical that
the rods use to absorb
photons and perceive
light.
Interpreting Sight Cont.
● Stereoscopic vision
● The single perception of a
slightly different image from
each eye
● how we detect depth
perception
● perceives distance, depth,
height, and width of objects
● brain puts together the
pictures from both eyes into
one vision
● brings the three
dimensional vision
bibliography
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