vision A

Question 1

how is vision on the back of the eye (retina)

Answer 1

reduced, upside down

Question 2

where is visual information transmitted to

Answer 2

the visual cortex

Question 3

what does the vestibular apparatus cotnrol

Answer 3

balance

Question 4

VOR purpose

Answer 4

keeps vision steady as head moves

Question 5

orbit

Answer 5

bony cavity protecting the eye

Question 6

nasolacrimal duct

Answer 6

drains tears into nasal cavity

Question 7

lacrimal gland

Answer 7

secretes tears

Question 8

retinal photoreceptor layers

Answer 8

ganglion cells
amacrine cells
bipolar cells
horizontal cells
cones and rods

Question 9

rays must pass through

Answer 9

cornea
anterior chamber
pupil
lens
vitreous
inner retinal layers (ganglion, amacrine, bipolar, horizontal) to reach photocereptors

Question 10

rays do not have to pass through

Answer 10

iris, retinal pigment epithelium, choriocapillaris, sclera

Question 11

visual based neural signals pass thorugh

Answer 11

photoreceptors, intermediate retinal neurons, retinal ganglion cells (optic nerve) to LGN to visual cortex

Question 12

where are blood vessels located in the eye

Answer 12

choroid layer

Question 13

what absorbs excess light in the retina

Answer 13

pigment epithelium

Question 14

what cell axons become the optic nerve

Answer 14

retinal ganglion

Question 15

where must light rays focus

Answer 15

fovea

Question 16

what initiates resolution of the finest detail

Answer 16

on the fovea, maximally focused image. bc light strikes the photoreceptors directly in the fovea bc the overlying neurons are pushed aside. photoreceptors at the fovea are less obscured by inner retinal layers

Question 17

is the lens convex or concave when it becomes more powerful

Answer 17

convex. converges divergent rays coming from close objects onto fovea

Question 18

focal length

Answer 18

distance from the centre of the lens to the focal point

Question 19

what needs no lens accomidation

Answer 19

far objects farther than 20 ft lead to parallel rays

Question 20

what controls lens shape

Answer 20

muscles in ciliary body

Question 21

far focus

Answer 21

ciliary body muscles relax. zonule ligaments tighten, lens is stretched.
decrease power
rays focus on fovea

Question 22

far focus PANS OR SANS

Answer 22

sympathetically controlled

Question 23

near focus

Answer 23

ciliary body muscles contract moving it inwards. zonule ligaments loosen, lens is fatter and convex. converge rays from behind fovea
increase power

Question 24

near focus PANS OR SANS

Answer 24

Parasympathetically controlled

Question 25

ciliary body shape

Answer 25

donut of muscle around base of iris

Question 26

normal eye

Answer 26

emmetropic far focused as default near needs accomidation lens gets fatter to converge and move light rays forward onto fovea as objects get closer

Question 27

neural pathways mediating accomodation

Answer 27

optic nerves to oculomotor nuclei to oculomotor nerves to ciliary body muscles

Question 28

oculomotor nuclei

Answer 28

edinger westphal nuclei

Question 29

optic nerve afferents

Answer 29

are driven from each eye and lead to binocular efferents controlling both eyes which leads to accomodation reflex

Question 30

low light conditions

Answer 30

iris dilator pupilae muscles contract radial fibres shorten pupil diameter increases

Question 31

high light conditions

Answer 31

iris constrictor pupilae muscles contract concentric fibres shorten pupil diameter decreases

Question 32

neural pathways mediating pupillary reflex

Answer 32

optic nerve to oculomotor nuclei to oculomotor nerves to iris muscles contrictor pupilae and dialator pupilae binocular efferents from optic nerve afferents

Question 33

visual acuity

Answer 33

spatial resolving capacity of visual system ability to see fine detail

Question 34

what is visual acuity limited by

Answer 34

diffraction, abherrations and photoreceptor density in the eye

Question 35

what does visual acuity target

Answer 35

recognition tasks, used in clinical visual acuity measurements that require the recognition or naming of a target such as snellen letters

Question 36

factors affecting visual acuity

Answer 36

refractive error size of pupil illumination time of exposure of the target area of the retina stimulated state of adaptation of the eye eye movement

Question 37

normal visual acuity

Answer 37

20/20 or 6/6 is the ability to resolve a spatial pattern separated by a visula angle of one minute of arc at 20 feet or 6 meters

Question 38

first number in snellen

Answer 38

test distance

Question 39

second number snellen

Answer 39

distance that the normal eye can see the same letters on the eye chart

Question 40

visual acuity

Answer 40

distance away from object that a normal subject can be to clearly see the detail

Question 41

how many min of arc are in the letter e

Answer 41

5 since there are 5 vertically contrasting parts to the e

Question 42

why are snellen letters sometimes sideways

Answer 42

to test ability to resolve a spatial pattern separted by a visual angle of one minute of arc

Question 43

legal blindness

Answer 43

20/200

Question 44

what does light not have to pass through that you keep forgetting

Answer 44

retinal pigment epitheliium and choriocapillaris