Scrub In. What is the function of vitreous humor? What does the pupil do when exposed to bright light? a. Maintain eye shape and provide color vision

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1 Scrub In What is the function of vitreous humor? a. Maintain eye shape and provide color vision b. Maintain eye shape and refract light rays c. Provide night vision and color vision d. Provide night vision and refract light rays What does the pupil do when exposed to bright light? a. Constrict b. Dilate c. Enlarge d. Nothing 1

2 3.04 Functions and disorders of the eye 2

3 Essential Questions What are the functions of the sensory system? What are some? How are sensory system disorders treated? How do you relate the body s communication to the sensory system? 3

4 Understanding the functions of the eye 4

5 External eye Orbit protects the eye Understanding the functions of the eye Eyelids and eyelashes - protect the eyes from small particles; provide a danger warning Conjunctiva secretes mucous to lubricate the eye Lacrimal glands produce tears Extrinsic muscles responsible for moving the eye and are attached to the sclera 5

6 Internal eye Intrinsic muscles changes size of the iris and pupil to control amount of light entering through the pupil Understanding the functions of the eye 6

7 Internal eye Cornea helps the eye focus Iris - controls the diameter and size of the pupil Pupil - allows light to enter the retina/ constricts when exposed to bright light Understanding the functions of the eye 7

8 Internal eye Ciliary body holds the lens in place with the suspensory muscles Lens focuses light rays on the retina and controls the process of accommodation (change in the shape of the lens to allow for near and distance vision) Aqueous humor - nourishes the cornea and the lens and gives the eye it's shape. Understanding the functions of the eye 8

9 Internal eye Sclera helps maintain the shape of the eye and protects what s inside Choroid provides oxygen and nourishment to the outer layers of the retina Retina - transmits images to the brain Understanding the functions of the eye 9

10 Understanding the functions of the eye Internal eye Vitreous humor maintains eye shape and refracts light rays 10

11 Understanding the functions of the eye Macula: responsible for clear, sharp central vision 11

12 Pathway of vision: Understanding the functions of the eye Cornea Pupil Lens Retina Optic Nerve Why can t you see in the dark? 12

13 Understanding the functions of the eye Rods and cones of the retina Functions of the rods and cones: they are sensitive to light; cones are responsible for color vision 13

14 Scrub In What is the medical term for a tiny abscess at the base of an eyelash? a. Hordeolum b. Cataract c. Blind spot d. Rod What is another name for nearsightedness: a. Myopia b. Hyperopia c. Astigmatism d. Amblyopia 14

15 Disorders of the eye Glaucoma Diabetic retinopathy Cataract Have you heard of these conditions? What do you know about them? 15

16 Disorders of the eye Cataract Lens of eye gradually become cloudy Frequently occurs in people over 70 Causes a painful, gradual blurring and loss of vision Pupil turns black to milk white 16

17 Disorders of the eye Cataract Treatment: Surgical removal of the lens 17

18 Color blindness Do you see the number? What is color blindness: the inability to distinguish colors Causes: hereditary Who is most likely to have color blindness: males Disorders of the eye 18

19 Disorders of the eye Conjunctivitis (Pink eye) Inflammation of the conjunctival membranes in front of the eye/ very contagious Symptoms: redness, pain, swelling and discharge Causes: bacteria or virus Treatment: antibiotic eye drops if bacterial 19

20 Detached retina is when the retina pulls away from the layer of blood vessels that provides it with oxygen and nourishment. The longer it goes untreated the higher the risk is of permanent damage 20

21 Detached retina Causes: shrinkage or contraction of the vitreous humor, injury, advanced diabetes, an inflammatory eye disorder Treatment: surgery 21

22 Disorders of the eye Diabetic retinopathy - a complication of diabetes that affects the eyes; caused by changes in the blood vessels in the retina Causes: elevated glucose levels over an extended period of time Symptoms: floaters, blurred vision, dark areas in your vision, vision loss Treatment: laser surgery 22

23 Disorders of the eye Glaucoma excessive intraocular pressure causing destruction of the retina and atrophy of the optic nerve Symptoms: develop gradually mild aching, loss of peripheral vision, halo around light Diagnosed: Tonometer (measures intraocular pressure) Treatment: drugs or laser surgery to lower the intraocular pressure 23

24 Disorders of the eye Macular degeneration Is a chronic eye disease that causes vision loss in the center of your field of vision. There are 2 types: Dry causes gradual thinning of the retina Wet abnormal blood vessels grow behind the macula causing fluid or blood to leak. This leads to distortion of the maculas shape. Diagnosis: eye exam, Amsler grid, angiogram Treatment: high doses of antioxidants and zinc, surgery 24

25 Compare the symptoms and treatments of these common eye disorders. Can a person have more than one of these disorders? 25

26 Presbyopia lens loses elasticity, can t focus on close or distant objects Treatment: bifocals Hyperopia farsighted; focal point beyond the retina because eyeball is too short. Would need glasses to see things up close. Treatment: convex lenses Myopia nearsighted; eyeball is enlongated. Would need glasses to see things far away Treatment: concave lenses Astigmatism irregular curvature of the cornea or lens, causing blurred vision and eye strain Treatment: corrective lenses 26

27 Testing vision Someone with eye problems would need to see an Ophthalmologist. An ophthalmoscope is an instrument for viewing inside of the eye Snellen eye chart chart that uses letters or symbols in calibration to check for vision defects What is 20/20: normal vision. This means that the patient sees the same line of letters at 20 feet that a normal person sees at 20 feet. What does PERRLA mean: Pupils Equal, Round, Reactive to Light and Accommodation 27