eyeball Flashcards
1
Q
visual activity
A
ability to see, measured w/ Snellen Eye chart
2
Q
Snellen Eye Chart
A
1st number= distance from chart
2nd number=feet person w normal vision can see chart
3
Q
cone
A
a type of photo receptor cell in retina, sees directly in front of you, three types see different wavelengths -red -blue -blue malfunction = color blindness
4
Q
rod
A
photo receptor sees gray, sees to the side of you, optic nerve + chaism to reach oppcipital lobe
5
Q
optic nerves
A
assists rods+cones
6
Q
depth perception
A
the ability to tell how close/far objects are to you and each other
1= sees two dimenensional
2= see+processes dif views of same object
-allows us to see optical illusions
7
Q
refraction
A
- density of light rays change they switch mediums while traveling through different parts of the eye, denser mass than air speed will change causing direction to change
- denser medium=more angle it changes
8
Q
accommodation
A
- lens +cornea work to expand or shrink to refocus light on retina
- cornea carries process, lens finely adjusts
- combo of reflex actions
- lens keeps focal length+distance between its center + focal point constant
- CILIARY MUSCLES help lens
9
Q
Convex lens
A
- larger to smaller
- lens is responsible
- sees far away objects
- light rays pass through eye and shrink and focus
- light waves converge at back of retina
10
Q
concave lens
A
- when light rays expand as passing through eye
- for focusing on close up objects
- light diverges to reach retina
11
Q
hyperopia
A
- far sided vision, things close up appear blurry and unclear
- emmertropia= normal 20/20
- when eyeball is short (not deep enough) or lens does not converge enough
- images hit retina before being focus, images go beyond retina
12
Q
Myopia
A
- near sided vision things far away = blurry/unclear
- eyeball too deep/long or when lens= too convex/curved
- images are projected to front of retina
13
Q
astigmatism
A
- condition = when cornea or lens is irregularly shaped + cause light rays to refract/ dont converge properly + not focus at certain point on retina
- causes blurry/ distorted images
- can be fixed w glasses, contacts, refractive surgery
14
Q
blind spot
A
- optic nerves exists through retina otw to brain
- no light sensitive receptors
- images that fall here cant be seen
- brain ignores the hole in visual input
15
Q
peripheral vision
A
- ability to see things not directly in front of you
- rods are close to edge of retina to control this, brain adds color based on surroundings and past sighting of these images
- stronger in dark
