The Eye

Question 1

Cornea

Answer 1

Protection, helps focus light on the retina

Question 2

Lens

Answer 2

Convex, focuses light on the retina

Question 3

Retina

Answer 3

• light, sensitive layer of cells
• rods = are sensitive to low light, but only black and white
• cones = are sensitive to colour but require higher light intensity

Question 4

Optic Nerve

Answer 4

Sends optical information from retina to brain, the attachment causes a blind spot

Question 5

Iris

Answer 5

Dilates or constricts to control the amount of light that enters the eye

Question 6

Ciliary Muscles

Answer 6

• changes the lens thickness

* accommodation is when the ciliary muscles change the lens shape, altering the lens focal length

Question 7

Hyperopia

Answer 7

• far-sightedness
• image is formed behind the retina
• lens/cornea combination is too weak or distance from lens to retina is too short
• a converging lens can reposition the image on the retina

Question 8

Myopia

Answer 8

• near-sightedness
• image is formed in front of the retina
• a diverging lens can reposition the image on the retina

Question 9

Presbyopia

Answer 9

• lens has lost elasticity and can’t easily change focus
• close objects are focus behind the retina, but distant objects are not affected
• converging lenses for close things, or bifocals

Question 10

Astigmatism

Answer 10

• cornea or lens is a little more cylindrical
• lines in one direction are more clearly focused than lines in another direction
• fixed with slightly cylindrical lenses

Question 11

Macular Degeneration

Answer 11

Age-related, progressive damage to the macula causing gradual loss of central vision

Question 12

Detached Retina

Answer 12

• sudden separation of the retina from the underlying layers

* can be surgically reattached, but if not done promptly the retina can lose its blood supply and be permanently damaged

Question 13

Cataracts

Answer 13

• the lenses gradually become translucent causing a progressive lack of vision
• treated by replacing the lenses with artificial ones

Question 14

Conjunctivitis

Answer 14

• pinkeye
• an inflamed conjunctiva, usually caused by bacterial/viral infection
• the white part of the eye appears pink or red

Question 15

Glaucoma

Answer 15

• the aqueous humor in the eye is constantly being replaced
• if new fluid is produced faster than the old fluid is reabsorbed, the intraocular pressure increases
• excessive eye-pressure can damage the optic nerve and cause blindness