EYE PROJECT

Austin PettyTravis Byrne

Period 6

Table Of Contents• 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 Eyethree 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 Continuedinner- retinal tunic

pigmented layer

accumulates vitamin A

sucks in light

nervous layer

catches light

converts light into-

action

Six extrinsic muscles of eye:

Parts/Functions ContinuedRetina:

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 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 ContinuedCornea

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

Parts/Functions ContinuedLens

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 chambers-

anterior chamber

between iris & cornea

full of aqueous humor

posterior chamber

between suspensory ligaments & iris

full of aqueous humor

Parts/Functions ContinuedChoroid 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 LabStep 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 EyeMyopia- 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 ContinuedWatery 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 with- hold-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 ContinuedDrooping 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 EyePink 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 ContinuedChalazion

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 & PerceptionNeural 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• 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?

• 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.

• 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

• 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?

• 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

• See Video of Interview and Answer Following Questions:

Questions-

1. 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• 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