The Eye Flashcards
1
Q
Cornea
A
Protection, helps focus light on the retina
2
Q
Lens
A
Convex, focuses light on the retina
3
Q
Retina
A
- 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
4
Q
Optic Nerve
A
Sends optical information from retina to brain, the attachment causes a blind spot
5
Q
Iris
A
Dilates or constricts to control the amount of light that enters the eye
6
Q
Ciliary Muscles
A
- changes the lens thickness
* accommodation is when the ciliary muscles change the lens shape, altering the lens focal length
7
Q
Hyperopia
A
- 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
8
Q
Myopia
A
- near-sightedness
- image is formed in front of the retina
- a diverging lens can reposition the image on the retina
9
Q
Presbyopia
A
- 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
10
Q
Astigmatism
A
- 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
11
Q
Macular Degeneration
A
Age-related, progressive damage to the macula causing gradual loss of central vision
12
Q
Detached Retina
A
- 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
13
Q
Cataracts
A
- the lenses gradually become translucent causing a progressive lack of vision
- treated by replacing the lenses with artificial ones
14
Q
Conjunctivitis
A
- pinkeye
- an inflamed conjunctiva, usually caused by bacterial/viral infection
- the white part of the eye appears pink or red
15
Q
Glaucoma
A
- 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