EYE PROJECT
Austin Petty
Travis Byrne
Period 6
Table Of Contents
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Parts of Eye & Function
Dissection Lab
Disorders of Vision & Treatment
Diseases of Eye & Treatment
Neural Pathways of Vision & Perception in Brain
Study Questions
Interview With Doctor Zuzana R. Gellner
Field Of Vision
Visual Illusions
The Cookie Page!!
Bibliography
Parts & Functions of Eye
three major layers of eye:
outer- fibrous tunic
cornea
major role in focusing
bends (refracts) light
sclera
protection & attachment of eye
upholds the shape of eye
middle- vascular tunic
iris
regulates amount of light to retina
ciliary body
releases aqueous humor
transforms frame of lens
choroid
takes in light
blood vessels provide eye tunics
Parts/Function Continued
inner- retinal tunic
pigmented layer
accumulates vitamin A
sucks in light
nervous layer
catches light
converts light intoaction
Six extrinsic muscles of eye:
Retina:
pigmented layer
accumulates vitamin A
sucks in light
nervous layer
catches light
converts light into action
photoreceptors
contains rods and cones
rods
more than 100 million in each eye
enhanced by low light
enhanced by shapes and movement
can’t separate small details
cones- cone shaped cells
distinguish fine details
about 7 million in each eye
high density in posterior center of retina
less sensitive
fovea centralis
most precise vision
no rods
macula lutea
yellowish
lots of cones
Parts/Functions Continued
Parts/Functions Continued
optic disk
where optic nerve (CN II) exits eye
no photoreceptors ---> BLIND SPOT
optic nerve (CN II)
forms with axons of ganglion neurons
Conjunctiva- mucus membrane over inner face of eye lids
lubricated
moist
palpebral conjunctiva
thick
inner surface
bulbar (ocular) conjunctiva
thin
anterior surface
superior & inferior conjunctiva sacs
both defend eye from materials entering eye
medication goes here often
PINKEYE-conjunctivitis
bacterial virus
dry & scaly
in need of vitamin A
highly contagious
Parts/Functions Continued
Cornea
major role in focusing
bends (refracts) light
abundant nerve supply
stimuli causes blinking
increase secretion-lachrymal glands
tough - - 5-layered membrane
Iris
between cornea & lens
circular shape
inside
circular muscle
radial muscle
color in eyes
due to amount of pigment
high-appear brown or black
low-appear blue,green, or gray
Pupil
center hole in iris
light is directed through
circular muscles
gets small in bright light/seeing close things
gets big in dim light/seeing far away things
Lens
Parts/Functions Continued
biconvex structure-flattened sphere
held in by ligaments
easily bendable
change in shape due to ciliary muscles
focusing &distance adjustments
transparent fibers
Ciliary Body
ciliary muscles
change shape of lens (focusing)
ciliary process
makes aqueous humor (clear watery fluid)
Suspensory Ligaments
attaches lens & ciliary body
Anterior Cavity
two chambersanterior chamber
between iris & cornea
full of aqueous humor
posterior chamber
between suspensory ligaments & iris
full of aqueous humor
Parts/Functions Continued
Choroid Plexuses
secretes aqueous humor into posterior chamber
Aqueous Humor
provides oxygen & nutrients to lens & cornea
Canal of Schlemm
pipes aqueous humor from anterior chamber into blood stream
Vitreous Humor - jelly like fluid
fills posterior cavity
passes light to retina
keeps up intraocular pressure
Protective Structures:
eyebrows
just above eyes on outside
keep moisture from running into eyes
perspiration (sweat)
oily fluids
shading eyes
prevents materials from superior contact
Parts/Functions Continued
eyelids (palpebrae)
close over eyeball
act as screen to keep particles out of eye
eyelashes
protect eyes from particles in air
nerve endings
touched ---> cause closing of eyelids
tear glands
lubricates eye
when closed washes matter from eye’s surface
*FACT* - Humans blink about every 6 seconds
Dissection Lab
Step 1- Have your dissection tools and tray out in front of you
Step 2- Remove your eyeball from the air-tight plastic carefully
Step 3- Next, take your eye ball and examine it and try to get an understanding of what you are dissecting *remember
you won’t know if your eye ball is the left or right Unless all ready specified.
Step 4- Now, remove all of the fatty tissues (the white and yellowish stuff) carefully not to cut any muscles or other
valuable things. Remember, you are trying to keep all of the parts together and connected the eyeball, so don’t
cut anything off except for the fatty tissues. Keep the cut fatty tissues in your dissection tray for now. * a trick
in removing the fat is to make small insertions and to look for creases in the eye ball where the fatty tissues meet
with other parts of the eye. Such as muscles.
Step 5- After you have taken most, if not all of the fat off, you should have your six extrinsic muscles. Now you will
be able to figure out if your eye ball is a left or right by the oblique muscles (superior and inferior for they go
towards the medial aspect of the body.
Step 6- Now find the back of the eyeball and you will find and area where it comes out.here you will cut into the eye
ball to find all of the vital parts inside of the eye. Take your razor and cut carefully and slowly downward make
a nice clean insertion. You will come to a hard texture which will be the sclera. Here you will stop and try to
separate the eye carefully keeping it all intact.
Step 7- Once you are inside of the eye, you will find all of the internal parts of the eye.
Step 8-You can come and ask us any questions you have concerning this dissection.Anything at all.Now go have fun!
Disorders Of Eye
Myopia- nearsightedness
Description: elongated shape of eye, improper refraction of light (focus to early)
Cause: inherited --detected between ages 8-12
Treatment: glasses, contacts, & REFRACTIVE SURGERY- serious cases
Hyperopia- Farsightedness (first form)
Description: ease in seeing distance & hard seeing nearer objects
Cause: eyeball is too short (light rays focus behind retina)
Treatment: glasses
Presbyopia- farsightedness (2nd form)
Description:lens of eye loses flexibility
Cause: aging
Treatment: reading glasses
Symptoms: vision diminishing,
cant see object up close
Disorders of Eye Continued
Watery Eyes
Description: excessively watery eyes, lack of necessary substances to keep eye moisturized
Cause: allergies, infections, small object lodged in eye
Treatment: see ophthalmologist
Dry Eyes
Description: very common, more common in women,
Cause: lack of tear production, allergic reaction to medications, tears can’t keep eye moist or at right p-h
balance
Treatment: replacing or conserving tears, lubricating ointments, SERIOUS CASES---> plug puncta to withhold-tears
Symptoms: burning of eyes, itching, excess tearing (sometimes)
Crossed Eyes (in children)-- strabismus---> eyes inward (esotropia) eyes outward (exotropia)
Description: misalignment,
Cause: born with it, develop early in life,
Treatment: see doctor when it comes up, earlier treatment, better the chance of treating
Cataract
Description: common, clouding of crystalline lens
Cause: aging, injury, diabetes
Treatment: surgery
frequently performed around the world
Disorders of Eye Continued
Drooping Eyelids
Description: loss of muscle elasticity
Cause: born with it, aging, allergic reaction, and other medications
Treatment: surgery
Symptoms: eyelid sags, if it impairs vision consult a health care provider for further information
Astigmatism
Description: irregular curvature of cornea (usually shaped like football)
Cause: look above
Treatment: contacts, glasses
Symptoms: blurry vision, headache, eye strain
Partial Color Blindness: Dichromatism
Description: mostly in males, inability to distinguish colors (hard w/ red and green), most common
Cause: defect in retina (other nerve portions of eye), heredity
Treatment: none
*TEST* - - - Given to public employees (police/firemen)
normal will see 57
partial color blindness will see 35
Diseases of Eye
Pink Eye - conjunctivitis
Description: inflammation of conjunctiva
Cause: bacterial or viral infection, allergy, irritated eye
Treatment: anti-biotic or ointment prescription
Symptoms: swelling, redness, irritation, yellow sticky discharge which causes eyelids to stick together
Flaking Eyelids (blepharitis)
Description: inflammation of eyelids
Cause: oily skin, dandruff (of eyelids), or dry eyes
Treatment: Medications & daily cleansing
Symptoms: irritation, itching, rarely red eye
Histoplasmosis
this disease is thought to have been spread from the lungs to the eye by a bacterial virus known as Histoplasma
Capsulatum spores which cause a mild inflammation
Blepharitis (swollen eyelids)
Description: inflammation of eye lids & lashes
Cause: excessive oil on eyelid, bacterial infection, allergic reaction, poor eyelid care
Treatment: see Optometrist
Diseases of Eye Continued
Chalazion
Description: inflammation of meibomian gland (in eyelid)
Cause: blockage of duct to eyelid surface---->it may be an infection
Treatment: soak in warm water, 6+ weeks surgical removal
Symptoms: pain, tenderness of eyelid, conjunctivitis
Dacryocystitis
Description: inflammation of lachrymal sac
Cause: not really known
Treatment: rub with warm pad, ointments, medication
Symptoms: swelling & redness at nasal side of eye
Ocular Albinism
Description: Lack melanin pigment
Cause: Inherited
Treatment: visual aids, Change in living conditions, surgery (not real effective)
Retinoblastoma
Description: rare, Causes malignant tumors --> retinal layer of eye
Cause: hereditary
Treatment: Removal of eye- if untreated could be fatal
Neural Pathway & Perception
Neural Pathway : takes sensory information to brain
Axons
the long, tubular extension of a neuron that transmits nerve impulses away from the cell body
Horizontal Cells
transmits info laterally
nervous layer of retina
help in color seeing
increases input of moving info to brain
Amacrine Cells
increase changes in illumination of retina
Optic Chiasma
axons cross over
axons enter optic tracts
Optic Tracts
axons from lateral (ipsilateral) & medial (contralateral)
has information from both halves of visual fields
Neural Pathway & Perception Continued
Lateral Geniculate Nuclei
thalamus
Visual areas of the Occipital Lobe
cerebrum
information ends up here on visual fields
Steps: photoreceptor---> bipolar neuron---> ganglion neuron---> optic nerve (CNII)--->
optic chiasma---> optic tract---> lateral geniculate---> visual cortex of occipital lobe
Perception:
Optic Nerves
give messages from retinas to lateral geniculate nuclei of thalamus
*Messages must be sent to both the primary visual areas and visual association areas for images to be scene
*complex things are interpreted in the temporal association areas
*when the primary visual areas are messed up, it results in blindness (the failure of seeing)
*in posterior portion of temporal lobe printed words may be made out
Study Questions
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Parts and Functions
1. Name the six eccentric muscles of the eye
2. The retina has two layers. Give those layers and their functions.
3. What is the difference between cones & rods?
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Disorders of Vision
1. What is the difference between nearsightedness and farsightedness? Why?
2. What causes Astigmatism?
3. Some of the symptoms of this disorder are itching, burning of the eyes and sometimes excess tearing.
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Diseases of eye
1. Name two diseases the inflames the eye and tell some information about those diseases.
2. ________________ is a disease that inflames the lachrymal sac.
3. This is an inflammation of the conjunctiva.
Study Questions Continued
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Neural Pathways
1. Write down the path of the axons.
2. What are two types of cells that help transmit information in the retina?
3. When the information gets to the visual areas of the occipital lobes, what information is there?
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Dissection
1. Can you identify if your eye is either a left on or a right one? What do you need to do first to make
sure?
2. Did you make big insertions or small insertions? Why ?
3. What is the color of fat? Muscle?
4. When you make your insertion into the eye, what is hard texture that you come upon? What color is
it?
5. What is the part that is greenish-bluish? What is the function for that?
6. What is the jelly-like substance inside of the eye?
Interview With Doctor Gellner
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See Video of Interview and Answer Following Questions:
Questions1. Are glasses more common than contacts? Why?
2. Name one technological advance in contacts.
3. According to Dr. Gellner, what is the most common eye disorder she comes across?
4. What is the first thing that Dr. Gellner does before a patient sees her for an appointment?
5. What instrument measures a person’s vision?
6. What instrument does Dr. Gellner use to measure the shape of an individual’s eye? What is the
measuring for?
7. What is the name of the microscope that Dr. Gellner uses?
Field Of Vision
This is a diagram of your field of vision. The blue and dark purple represent where you can see
with your left eye. The light purple and dark purple represent what you can see with the right eye. Dark
purple shows your field of binocular vision.
Why do you think that with binocular vision you see a smaller area?
Visual Illusions
(1) Are the two lines intersecting?
What do you think?
(2) Which like segment is
longer? What do you think?
Answers: (1) the line segments do not intersect. (2) The line segments are the same
Visual Illusions Continued
(3) This is a lithograph that was drawn by M. C. Escher and represents Einstein’s theory of
relativity “perception changes depending upon one’s position and motion.”
The Cookie Page!!!
*Refer to the cookies
Statistics Six out of every ten people have Brown eyes
Two out of every ten people have Green eyes
Two out of every ten people have Blue eyes
*This shows that the majority of people in the world have
brown eyes. This goes to show that the color brown in eyes
is the DOMINATE GENE.*
Enjoy!!!!
Bibliography
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Human Anatomy & Physiology - Second Edition - Solomon - Schmidt Adragna - copyright 1990 by Saunders College Publishing
Encarta 1995 - CD
www.encarta.msn.com
Grolier's Encyclopedia - CD
Your Human Body - CD
Canadian Ophthalmological Society
www.I-care.net
Eye Clinic Surgery Information
www.rochestereyecare.com
yahoo.com
www.intelihealth.com
www.nei.nih.gov/
Glaucoma Research Foundation - Rita Loskill
John Hopkins Health Information
The Question & Answer CD About the Human Body
http://www.eyesite.com/Eye_Problems/eye_problems_disease.htm