Chapter 14, Lesson 3

Guided Reading Activity 52

Eye Care

1. What percentage of sensory information your brain receives

comes by way of your eyes?More than 70%.

2. What is the function of the eyes?

• To gather light.

3. What controls the amount of light that enters the eye?

• The size of the pupil.

4. Describe the function of each of the following:

4a. Orbits

• Boney sockets• Hold eyes in place

4b. Layer of fat surrounding each eyeball

• Cushions the eye ball inside the socket.

4c. Eyebrows, eyelashes, and eyelids

• Protect the eyes from foreign particles and bright lights.

4d. Lacrimal gland

• Secrets tears into ducts that empty into the eye.

4e. Tears.

• Keep surface of eye moist.

• Clear of foreign particles.

5. What are the two main parts of the eye?

• The optic nerve

• The eyeball wall

6. List the function of the following parts of the eye.

a. Sclera

• The white of the eye• Protects inner

layers of the eye.• Supports and

shapes the eyeball.

Sclera-----------

b. Cornea

• Bends and focuses light before it enters the lens.

Cornea-----

c. Choroid

• Lines the inside of the sclera.

• Contains blood vessels which nourish the eye.

Choroid-----

d. Iris

• Muscles of the iris control the size of the pupil.

• Give eye color.

Iris---------------

e. Pupil

• Allows light to reach the inner eye.

Pupil----------

f. Retina• Allows images to be cast by the cornea.

Retina------------------------------

g. Rods

• Allows us to see in dim light.

• Black and white.

h. Cones

• Allow us to see color.

i. Lens

• Refines the focus of images on the retina.

Lens--------------

j. Aqueous humor

• Provides nutrients to the structures of the eye.

Aqueous Humor--------------

k. Vitreous humor.

• Helps the eyeball stay firm.

Vitreous Humor----------------------------

7. List four health behaviors you can practice every day to keep your eyes

healthy.

• Eat a well balanced diet.• Protect your eyes.• Rest your eyes regularly• Have regular eye exams

8. Explain the difference between myopia and hyperopia.

• Hyperopia—Farsightedness– Person can see far– Close objects appear blurry.

Myopia—NearsightednessPerson cannot see far.Person can see close

Compare the shape

of the eyeball

9. Describe the following vision problems and eye diseases.

9a. Astigmatism

• Cornea or lens is irregularly curved.

•Makes images appear blurry.

9b. Strabismus

• Muscles of the eyes appear weak.

• Cause one or both eyes to move off center.

• Cross-eye:– Eyes pull towards the nose.

• Wall-eye– Eye (s) pull away from the nose.

9. Colorblindness

• Red-green color blindness is very common among males, affecting approximately 7% of the male population.  It is much less common in females, affecting less than 1%.

9. Colorblindness

9. Colorblindness

9. Colorblindness

9. Colorblindness

• Red-green color blindness is very common among males, affecting approximately 7% of the male population.  It is much less common in females, affecting less than 1%.

If we have 400 students in our high school, with 250 males and 150 females, determine how many students in our school may be colorblind using the above information.

MATH PROBLEM ANSWER

• 250 X .07 = 17.5

• 150 X .01 = 1.5

• 17.5 + 1.5 = 19 Students

9c. Glaucoma:

• Pressure inside the eye is abnormally high leading to irreversible damage of the retina and optic nerve.

• Can cause vision loss.

9d. Cataracts:

• The lens becomes cloudy.

9. Cataracts:

• Surgery

9e. Macular degeneration

• Light sensing cells in portion of the retina directly opposite the lens begin to malfunction.

It can cause vision loss.

Macular degeneration

• The Amsler Grid is often used to monitor diseases affecting the retina, especially macular degeneration.  Any abnormal area in the grid, or any change in its appearance should be checked with an eye examination on an urgent basis.

10. Describe three other diseases of the eye.

• Sty– Swelling of a sebaceous gland near the

eyelash.

• Conjunctivitis--Pinkeye– Inflammation of the thin membrane that

covers the sclera lining of the eyelids.

• Detached retina– Portion of the retina separates from the

choroid.