vision

Question 1

what is the optic nerve

Answer 1

ganglion nerve fibres

Question 2

what happens at the optic chiasm

Answer 2

half of nerve fibres cross

Question 3

what is optical tract

Answer 3

ganglion nerve fibres exit as optic tract

Question 4

what happens at lateral genticulate nucleus in thalamus

Answer 4

ganglion nerve fibres synapse onto optic radiation

Question 5

what is the optic radiation

Answer 5

4th order neuron

Question 6

where does optic radiation go

Answer 6

primary visual cortex (striate cortex) within occipital lobe

Question 7

visual pathway anatomy diagram

Answer 7

slide 2

Question 8

first order neurones in retina

Answer 8

rod and cone retinal photoreceptors

Question 9

second order neurones in retina

Answer 9

retinal bipolar cells, which modulate signal

Question 10

third order neurones in retina

Answer 10

retinal ganglion cells (optic nerve)

Question 11

what do lesions anterior to optic chiasma affect

Answer 11

visual field in one eye only

Question 12

what do lesions posterior to optic chiasma affect

Answer 12

visual field in both eyes

Question 13

what fibres cross at optic chiasma

Answer 13

originating from nasal retina, responsible for temporal visual field

Question 14

what fibres don’t cross at optic chiasma

Answer 14

originating from temporal retina, responsible for nasal visual field

Question 15

diagram of crossing and uncrossing at optic chiasma

Answer 15

slide 4

Question 16

what happens if lesion at optic chiasma

Answer 16

damaged crossed ganglion fibres from nasal retina in both eyes, causing temporal field deficit in both eyes (bitemporal hemianopia)

Question 17

what happes if right sided lesion posterior to optic chiasma

Answer 17

left homonymous hemianopia in both eyes

Question 18

what happes if left sided lesion posterior to optic chiasma

Answer 18

right homonymous hemianopia in both eyes

Question 19

disorders of visual pathway diagram

Answer 19

slide 5

Question 20

what typically causes a bitemporal hemianopia

Answer 20

enlargement of pituitary gland tumour

Question 21

what typically causes homonymous hemianopia

Answer 21

stroke (cerebrovascular incident)

Question 22

what typically is affected if superior or inferior field defect

Answer 22

eye problem e.g. glaucoma

Question 23

what typically is affected if left or right field defect

Answer 23

neurological problem

Question 24

type of vision defect if problem in occipital lobe (e.g. infarction)

Answer 24

macular sparing as part of central vision spared, unless massive occipital lobe trauma