anat and physiology of vision 2

Question 1

what are 2 visual fields and what do they project onto

Answer 1

nasal - onto temporal retina

temporal - onto nasal retina

Question 2

how is image that is projected oriented

Answer 2

upside down and laterally inverted

Question 3

where does retinal processing occur

Answer 3

middle 3 layers of the retina

Question 4

what does retinal processing do

Answer 4

drown out much of the excess light noise

Question 5

3 reasons visual acuity is high in fovea

Answer 5

1. anatomical structre
2. types of photo receptors
3. ratio of ganglion cells to receptors

Question 6

what is anatomically significant about fovea (3)

Answer 6

1. avascular
2. only photoreceptors and a few glia -not 8 layers on top
3. ganglion cells divert around fovea

Question 7

where are most rods and cones

Answer 7

cones - in fovea

rods - around the fovea

Question 8

average ratio of ganglia to receptor in retina andfovea

Answer 8

retina 370:1
fovea 1:1
periphery 1000:1

Question 9

what is function of retinal pigmented epithelium

Answer 9

provides metabolic and ionic conditions neccesary for rods and cones

Question 10

what happens to RPE with age

Answer 10

age related macular degen - get debris (drusen) that collects in macula and causes vision problems

Question 11

3 types of macular disease

Answer 11

1. wet ARMD - get blood into spaces
2. dry ARMD - drusen accumulation
3. subretinal fibrosis - end stage macular degen

Question 12

5 potential causes of optic nerve pathology

Answer 12

1. glaucoma
2. optic neutitis
3. ischemia
4. inflammation
5. compression

Question 13

3 areas of brain where signals from retina are sent

Answer 13

1. suprachiasmatic nucleus of hypothalamus - bio clock
2. lateral geniculat of thalamus - relays to visual cortex
3. pretectal region of midbrain - pupillary light reflex

Question 14

where are projections

Answer 14

review color slides

Question 15

how does field loss project

Answer 15

upside down and backwards to the site of visual pathway lesion

Question 16

what does loss respecting horizontal midline of visual suggest

Answer 16

retina/optic nerve lesion

Question 17

what does loss respecting vertical midline of visual suggest

Answer 17

optic chiasm or retro chisamic

Question 18

4 possible causes of chiasmal defects

Answer 18

1. pit. adenoma
2. suprasellar meningioma
3. craniopharyngioma
4. aneurysm of ICA

Question 19

which hemisphere does right visual field project to?

Answer 19

left

Question 20

how much does fovea get represented in cortex

Answer 20

1%, but gets half