3.04 Functions and disorders of the eye 3.04 Understand the functions and disorders of the sensory system 1

3.04 Functions and disorders of the eye

3.04 Understand the functions and disorders of the sensory system

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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?

Understanding the functions of the eye


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Understanding the functions of the eyeExternal eyeExternal eyeOrbit-surrounds the eye to Orbit-surrounds the eye to protect itprotect it

Eyelids and eyelashesEyelids and eyelashesWomen blink twice as often as men. Why do we blink?

Conjunctiva-sac that lines the Conjunctiva-sac that lines the eyelid and secretes mucus to eyelid and secretes mucus to lubricate the eyelubricate the eye

Lacrimal apparatus(glands)-Lacrimal apparatus(glands)-secrete tears to cleanse and secrete tears to cleanse and moisten the eye; also contain moisten the eye; also contain enzymes to fight bacteria; tears enzymes to fight bacteria; tears drain into nasal cavity.drain into nasal cavity.

Extrinsic muscles-moves the eyeExtrinsic muscles-moves the eye

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External eyeExternal eye

Extrinsic Extrinsic musclesmuscles


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Which extrinsic muscle

Which extrinsic muscle

allows you to look upward?

allows you to look upward?

Understanding the functions of the eyeInternal eyeInternal eyeCornea-allows for Cornea-allows for passage of light rayspassage of light rays

Iris-controls the Iris-controls the amount of light entering amount of light entering the pupilthe pupil

Pupil-regulates the Pupil-regulates the amount of light passing amount of light passing to the retinato the retina


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Understanding the functions of the eyeInternal eyeInternal eyeCiliary body-holds the Ciliary body-holds the lens in placelens in place

Lens-focuses images on Lens-focuses images on the retina; this is known as the retina; this is known as accommodationaccommodation

Aqueous humor-helps Aqueous humor-helps maintain the shape of the maintain the shape of the eyeballeyeball


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Understanding the functions of the eyeInternal eyeInternal eye

Sclera-maintains eye Sclera-maintains eye shape and protects shape and protects internal structures. internal structures.

Choroid-contains Choroid-contains blood vessels to nourish blood vessels to nourish the eyethe eye

Retina-form images of Retina-form images of objectsobjects


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Internal eyeInternal eye

Vitreous humor-Vitreous humor-maintains the maintains the eyeball’s shape and eyeball’s shape and refracts light raysrefracts light rays


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A yellow disc that contains the cones forcolor vision.


Process of SeeingProcess of Seeing

Trace the field of Trace the field of vision.vision.

Is there anything Is there anything strange about this strange about this picture? Explainpicture? Explain


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Why can’t you see in the dark?



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What happens as you move What happens as you move your paper away from and your paper away from and

toward to your eye?toward to your eye?

VisionVision

Rods and cones of the retina

What are the functions of the rods and cones?3.04 Understand the functions and

disorders of the sensory system13


Rods and cones of the retina


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*Rods-sensitive to DIM light; help us to see at night.

*Cones-sensitive to BRIGHT light; responsible for color vision.


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Check your knowledge!


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Vision ActivityVision Activity

Do you see what I see?Do you see what I see?

Disorders of the eye


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CataractCataract

GlaucomaGlaucoma

Hyperopia

Hyperopia

MyopiaMyopia

Presbyopia

PresbyopiaAstigmatismAstigmatism

DiabeticDiabetic retinopathyretinopathyDetachedDetached retinaretina

Have you heard of these conditions?What do you know about them?

Color blindnessColor blindness

ConjunctivitisConjunctivitis



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Cataract-the lens becomes cloudyCataract-the lens becomes cloudyCommon in people over70 yrs. of age.

Causes a painless, blurring or loss of vision,may see halos around lights at night.


CataractCataract

How is a cataract How is a cataract treatedtreated??

Laser surgery or Laser surgery or surgical removal of surgical removal of the lens; lens the lens; lens implantimplant


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Disorders of the eyeColor blindnessColor blindnessDo you see the number?Do you see the number?What is color blindness?What is color blindness?What What causes it? causes it?

Cone cells do not work Cone cells do not work properly; hereditaryproperly; hereditaryWho is most likely to have Who is most likely to have color blindness?color blindness?

Affects 8-10% of the male Affects 8-10% of the male populationpopulation


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Disorders of the eyeHordeolum (aka sty)-tiny abcess at the base of an Hordeolum (aka sty)-tiny abcess at the base of an

eyelasheyelash

What are the What are the symptomssymptoms??

Eyelid is red, painful, swollenEyelid is red, painful, swollen

How is it How is it treatedtreated??

Warm, wet compressesWarm, wet compresses

to relieve pain andto relieve pain and

promote drainagepromote drainage


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Disorders of the eyeConjunctivitis-inflammation of the Conjunctivitis-inflammation of the conjunctival membrane; conjunctival membrane;

aka “pink eye”aka “pink eye” What are the What are the symptomssymptoms??

Redness, pain, swelling, discharge of Redness, pain, swelling, discharge of mucus; usually begins in one eye and mucus; usually begins in one eye and spreads to the other by a washcloth or spreads to the other by a washcloth or hands.hands. How is it How is it treatedtreated??

Eyewashes and antibioticsEyewashes and antibiotics


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Detached retinaDetached retina


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Discuss what happens in this Discuss what happens in this process. process. The vitreous fluid The vitreous fluid contracts with age and pulls contracts with age and pulls on the retina causing a tear.on the retina causing a tear.

What is the relevance to What is the relevance to health? health? May cause blindnessMay cause blindness


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Detached retinaDetached retina

Compare this process Compare this process to the previous picture.to the previous picture.

What might What might causecause this this condition?condition?Aging or a traumatic Aging or a traumatic injury to the eyeinjury to the eye

Disorders of the eyeDiabetic retinopathy-caused by Diabetic retinopathy-caused by changes in blood vessels in the changes in blood vessels in the retina; blood vessels may swell retina; blood vessels may swell and leak or abnormal vessels and leak or abnormal vessels may grow on the retinamay grow on the retinaWhat are theWhat are the symptomssymptoms??No symptoms in early stages; in No symptoms in early stages; in later stages may see red spots.later stages may see red spots.

Explain the impact on vision.Explain the impact on vision.Leading cause of blindness in Leading cause of blindness in American’s.American’s.


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Diabetics must have regular eye checks!

Disorders of the eyeGlaucoma-overproduction of Glaucoma-overproduction of aqueous humor causing destruction aqueous humor causing destruction of the retina and atrophy of the optic of the retina and atrophy of the optic nervenerveWhat are the common What are the common symptomssymptoms of of glaucoma?glaucoma?

Mild aching of the eye, loss of Mild aching of the eye, loss of peripheral vision, halo around the eyeperipheral vision, halo around the eyeHow is it How is it diagnoseddiagnosed??

Use of 3 tests to diagnose: tonometry, Use of 3 tests to diagnose: tonometry, opthalmoscopy, field testopthalmoscopy, field test How is it How is it treatedtreated??

Miotic meds to decrease aqueous Miotic meds to decrease aqueous humor productionhumor production


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Disorders of the eyeMacular degeneration-occurs with aging; Macular degeneration-occurs with aging; straight lines look wavy, blind spots appear.straight lines look wavy, blind spots appear.

Compare the Compare the two typestwo types..

Dry-gradual thinning of the retina; central Dry-gradual thinning of the retina; central vision decreases; no known treatmentvision decreases; no known treatment

Wet-new blood vessels grow behind the macula Wet-new blood vessels grow behind the macula and distorts its shape; treated with injectable and distorts its shape; treated with injectable med (Avastin), laser surgerymed (Avastin), laser surgery

How is it How is it diagnoseddiagnosed? On routine exam the ? On routine exam the doctor notices doctor notices yellow depositsyellow deposits under the retina under the retina

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Compare the symptoms and treatments of these common eye disorders.

Can a person have more than one of these disorders? Explain.

Problems with FocusProblems with Focus


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Compare the symptoms and treatments of these common eye disorders.

Can a person have more than one of these disorders? Explain.

Problems with FocusProblems with Focus

Hyperopia-”farsightedness”; objects must be moved farther awayto be seen.Myopia-”nearsightedness”; objects must be brought close to theeye to be seen.Presbyopia-the lenses lose their elasticity causing problems focusingon close objects; usually occurs after the age of 40. Astigmatism-irregular curvature of the lens or cornea; causes blurredVision; special eye glasses helps the condition.

Testing vision

How do we test visual How do we test visual acuity?acuity?

What is 20/20?What is 20/20?

What does PERRLA What does PERRLA mean?mean?


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Testing vision


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Ophthalmoscope-lighted instrumentused to view the eye.

Ishihara-test for color-blindness

Snellen chart->>>>>>>>>>>>>>>>>>>>>>

Optician-a maker or dealer of lensesor contacts

Ophthalmologist-specialist of the eye



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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 Functions and disorders of the eye

The EndThe End


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3.04 Functions and disorders of the eye 3.04 Understand the functions and disorders of the sensory system 1