This document discusses the functions and disorders of the eye. It describes the external and internal structures of the eye, including the retina, cornea, lens, and muscles. The eye functions to take in light and form images, which are then transmitted to the brain via the optic nerve. Common disorders mentioned include cataracts, glaucoma, macular degeneration, color blindness, and detached retinas. Symptoms, causes, diagnoses, and treatments are covered for several eye conditions. The document also addresses how vision is tested to evaluate acuity and eye health.
2. 3.04 Understand the functions and
disorders of the sensory system
Essential Questions
•What are the functions of the sensory system?
•What are some disorders of the sensory system?
•How are sensory system disorders treated?
•How do you relate the body’s communication to
the sensory system?
3.04 Understand the functions and
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disorders of the sensory system
4. Understanding the
functions of the eye
External eye
Orbit
Eyelids and eyelashes
Conjunctiva
Lacrimal apparatus
Extrinsic muscles
3.04 Understand the functions and
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disorders of the sensory system
5. Understanding the
functions of the eye
External Eye
Extrinsic Muscles
Superior rectus
Inferior rectus
Lateral rectus
Medial rectus
Superior oblique
Inferior oblique
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disorders of the sensory system
6. Understanding the
functions of the eye
Internal eye
Cornea
Iris
Pupil
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disorders of the sensory system
7. Understanding the
functions of the eye
Internal eye
Ciliary body
Lens
Aqueous
humor
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disorders of the sensory system
8. Understanding the
functions of the eye
Internal eye
Sclera
Choroid
Retina
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disorders of the sensory system
9. Understanding the
functions of the eye
Internal eye
Vitreous
humor
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disorders of the sensory system
11. Understanding the
functions of the eye
Process of Seeing
Trace the field of
vision.
Is there anything
strange about this
picture? Explain
Why can’t you see in the dark?
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disorders of the sensory system
12. Understanding the
functions of the eye
Vision
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disorders of the sensory system
13. Understanding the
functions of the eye
Rods and cones of the retina
What are the functions of the rods and cones?
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disorders of the sensory system
14. !
now ledge
k
e ck your
Ch
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disorders of the sensory system
15. Vision ActiVity
Do you see what I see?
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disorders of the sensory system
16. Disorders of the eye
Pres
Astigmatism Glaucoma
byop
ia
Detached re Diabetic retinopathy
tina
n e ss opia
Color blind Cataract Hy per
My Conjun
opia ctivitis
Have you heard of these conditions?
What do you know about them?
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disorders of the sensory system
17. Disorders of the eye
Cataract
Describe this lens.
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disorders of the sensory system
18. Disorders of the eye
Cataract
How is a
cataract
treated?
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18
disorders of the sensory system
19. Disorders of the eye
Color blindness
Do you see the
number?
What is color
blindness?
What causes it?
3.04 Understand the functions and
19
disorders of the sensory system
20. Disorders of the eye
Conjunctivitis
What is conjunctivitis?
What are the symptoms?
What causes it?
How is it treated?
3.04 Understand the functions and
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disorders of the sensory system
21. Detached retina
Discuss what happens
in this process.
What is the relevance
to health?
3.04 Understand the functions and
21
disorders of the sensory system
22. Detached retina
Compare this process
to the previous picture.
What might cause this
condition?
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disorders of the sensory system
23. Disorders of the eye
Diabetic
retinopathy
What causes diabetic
retinopathy?
What are the
symptoms?
Explain the impact
on vision.
3.04 Understand the functions and
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disorders of the sensory system
24. Disorders of the eye
Glaucoma
What are the
common symptoms
of glaucoma?
How is it
diagnosed?
How is it treated?
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disorders of the sensory system
25. Disorders of the eye
Macular degeneration
What is macular degeneration?
Compare the two types.
How is it diagnosed?
What is the treatment?
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disorders of the sensory system
26. Problems with Focus
Compare the symptoms and treatments of these
common eye disorders.
3.04 Understand the functions and
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disorders of the sensory system
27. Testing vision
How do we test visual
acuity?
What is 20/20?
What does PERRLA
mean?
3.04 Understand the functions and
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disorders of the sensory system
28. 3.04 Understand the functions and
disorders of the sensory system
Essential Questions
•What are the functions of the sensory system?
•What are some disorders of the sensory system?
•How are sensory system disorders treated?
•How do you relate the body’s communication to
the sensory system?
3.04 Understand the functions and
28
disorders of the sensory system
29. 3.04 Functions and
disorders of the eye
The End
The End
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disorders of the sensory system
Notes de l'éditeur
Orbit- the eye socket Eyelids – the covering of the eye Eyelashes-the hair on our eyelids Conjunctiva- the thin membrane that lines the eyelids and covers part of the eye. It secretes mucus to help lubricate the eye Lacrimal apparatus- gland located above the lateral area of the eye. Duct- corner of the eyes and empties into the nasal cavity. Extrinsic muscles- provide movement to the eyeball
Superior- rolls eyeball upward Inferior- rolls eyeball downward Lateral- rolls eyeball laterally Medial rectus-rolls eyeball medially Superior oblique-rolls eyeball on its axis, moves cornea downward and laterally Inferior oblique- rolls eyeball on its axis, moves cornea upward and laterally
Cornea - the very front of the eye. It is a clear area. Sometimes referred as the window of the eye. Consists of 5 layers of flat cells arranged much like sheets of plate glass. It contains pain and touch receptors. It is very sensitive to any foreign particles. Its function is to allow for the passage of light rays. Pupil - circular opening in front of the choroid. Which controls the amount of light let in to the eye. Bright light= pupils small Dim light=large pupils Iris - colored muscular layer surrounding the pupil. This is the structure which gives up eye color
Ciliary body- smooth muscle that holds the lens in place by means of suspensory ligaments. Lens - is located between the anterior and posterior chamber. It is a crystalline structure located behind the iris and pupil. It is disc shaped structure. The lens focuses images on the retina. Aqueous humor - watery fluid which fills the anterior chamber. It is constantly replenished by the blood vessels behind the iris. It helps to maintain the sphere shape of the eyeball. It also helps to bend or refract light rays as they pass through the eye
Sclera - the outer layer ( the whites of the eye). Tough fibrous capsule which maintains the shape of the eye. Choroid – the middle layer of the eye. Contains blood vessels to nourish the eye and it also has a dark pigment making it dark which prevents light reflection within the eye. Retina - is the innermost part of the eye. It is located between the posterior chamber and the choroid. This is where light rays from an object form an image. After the image is focused on the retina, it travels via the optic nerve to the visual part of the brain (occipital lobe). It is while the retina where rods and cones are located.
Vitreous humor- jelly like substance that fills the posterior chamber to help maintain the sphere shape of the eyeball. It also helps to bend or refract light rays as they pass through the eye
Macula - Yellow disk in the back of the eye Fovea centralis- where cones are located. Around the fovea is where rods are located Optic disk- located to the side of the fovea. Nerve fibers from the retina gather here to form the nerve. It has neither rods nor cones….there is no vision in this spot “blind spot”.
Images in the light-cornea-pupil-lens-where the light rays are bent/refracted-retina- rods and cones (nerve cells) pick up the stimulus- optic nerve- optic chiasma (where the two optic nerves cross)- optic tracts- occipital lobe for the brain to interpret.
Rods and cones are nerve cells with specific jobs related to sight Rods Active in dim light Peripheral vision Do not perceive color Cones Active in bright light Perceive color
Red white and blue activity- How your eyes' receptors (CONES) can get tired. When they don't work as usual, you may see an afterimage in colors that are different from the image you were looking at. An afterimage is when your eyes see something that isn't there. Two eyes better than one How two eyes give you more depth perception, which is the ability to judge how near or far objects are
Cataracts is a condition where the lens of eye gradually becomes cloudy. Cataracts will cause a painless gradual blurring and loss of vision. The pupil will change from black to a milky white color. People may complain of seeing halos around lights and being blinded at night by oncoming headlights. Frequently happens to people over 70 years old.
Tx- laser surgery or surgical removal of the lens and a postoperative substitution of contact lens or glasses. They can also have a intraocular lens implanted directly behind the cornea.
Color blindness is the inability to distinguish colors. There are three specific types of cone cells in the retina related to primary colors; red blue and green. The cone cells are affected in color blindness. It is hereditary.
Is the inflammation of the conjuctival membranes. Redness, pain, swelling, and discharge of mucus occurs. Known as “pink eye”. Usually starts in one eye but quickly spreads to the other. It is highly contagious. Caused by bacteria or virus Good handwashing is an important way to prevent it from being spread. Don’t share wash clothes or eye makeup. Bacterial is treated with antibiotics. Otherwise the use of eye washes or eye irrigants will cleanse the conjuctiva and the relief the inflammation and pain.
Can occur with aging or by trauma to the eye. The retina of the eye will actually tear. S/S- loss of peripheral vision and then the loss of central vision. Early detection is the vital to prevent permanent loss of vision. Tx- repaired with laser or a freezing technique
The vitreous humor in the posterior chamber contracts as it ages and will pull on the retina.
Is the leading cause of blindness in American adults. It is caused by the changes in the blood vessels in the retina. Blood vessels may swell and leak or abnormal blood vessels may grow on the retina. Since there are no symptoms in the early stages, this is why diabetic should have annual eye exams. Advanced diabetic retinopathy may cause bleeding and the person would see red spots. Laser surgery is usually effective and can reduce the risk of blindness by 90%.
Glaucoma is a condition of excessive intraocular pressure resulting in the destruction of the retina and atrophy of the optic nerve. The condition results from the overproduction of aqueous humor ( the fluid in the anterior chamber) or an obstruction preventing the fluid from being absorbed Symptoms are gradual. They include mild aching, loss of peripheral vision, and a halo around light. Glaucoma may occur with aging and has no symptoms. It is important for people to be tested annually- especially those over 40 . Puff of air in the eye, visualization of the optic nerve and central field testing are three tests to diagnose glaucoma. Tx- miotic drugs to constrict the pupil thus increasing the outflow of aqueous humor or drugs to reduce the production of aqueous humor by the eye. The goal is to reduce the intraocular pressure. Laser surgery or incisional surgery to increase the flow of aqueous humor has been successful also.
Occurs as the person ages. In the central part of the retina is the macula which is responsible for sharp central vision. There will be a dimming or distortion of vision that is most obvious with reading. One form- straight lines will look wavy and there may be blind spots in the visual field. Dry- the main defect is a gradual thinning of the retina. This slowly progresses, there will be reduced central vision but you will not become totally blind and there is no tx. Wet- new blood vessels grow behind the macula which causes leaking, bleeding, and distortion of the macula. Drug treatment to destroy those new blood vessels may work to correct this form. Also laser treatment may be used.
Hyperopia (farsightedness)- the focal point is beyond the retina because the eyeball is shorter than normal. Objects must be moved further away from the eye to be seen clearly. Convex lenses will correct this. Myopia (nearsightedness)- the focal point is in front of the retina because the eyeball is elongated. Objects must be brought closer to the eye to be seen clearly. Concave lenses will correct this Presbyopia- the lenses lose their elasticity resulting in a decrease in the ability to focus on objects close up. Usually occurs after the age of 40. “reading glasses” Astigmatism - condition in which there is an irregular curvature of the cornea or lens which causes blurred vision and possible eyestrain. A special prescription eyeglass will help correct this
20/20 vision is a term used to express normal visual acuity (the clarity or sharpness of vision) measured at a distance of 20 feet. If you have 20/20 vision, you can see clearly at 20 feet what should normally be seen at that distance. If you have 20/100 vision, it means that you must be as close as 20 feet to see what a person with normal vision can see at 100 feet. 20/20 does not necessarily mean perfect vision. 20/20 vision only indicates the sharpness or clarity of vision at a distance. There are other important vision skills, including peripheral awareness or side vision, eye coordination, depth perception, focusing ability and color vision that contribute to your overall visual ability. Pupils Equal Round Reactive Light Accomodation
