Lecture 10 Visual Systems

Question 1

What are the layers of the retina?

Answer 1

Internal limiting membrane 
Nerve fiber layer: axons of ganglion cells
Ganglion cell layer
Inner plexiform layer: synaptic zone for bipolar, amacrine and galngion cells
Inner nuclear layer
Outer plexiform layer 
Outer nuclear layer: soma of receptors
External limiting membrane
Layer of rods and cones 
Pigmented epithelium

Question 2

Which photoreceptor is absent in fovea centralis?

Answer 2

rods

Question 3

Clinically, lesions of the visual system are always described int terms of what?

Answer 3

their visual field deficits from the perspective of the patient’s right or left

Question 4

What does the visual field project onto the retinal field?

Answer 4

inverted and reversed

Question 5

What constitutes the primary pathway for visual invormation?

Answer 5

retinogeniculocalcarine pathway

Question 6

Where do fibers of the hemiretina course in the optic chiasma ? (First rule of retinotopic projection)

Answer 6

Fibers from the temporal hemiretina do NOT cross in the optic chiasma
Fibers from nasal hemiretina cross in the optic chiasma

Question 7

What is the Rule of L’s?

Answer 7

information from the Lower hemiretina projects to the Lateral part of the Lateral geniculate body, the Loop of meyer and the Lingual gyrus

Question 8

What is maintained throughout the system from the retina to visual cortex?

Answer 8

retinotopic organizations

Question 9

Describe homonymous visual fields

Answer 9

left nasal visual field = right temporal visual field

Question 10

Describe heteronymous visual fields

Answer 10

refer to noncorresponding visual fields

Question 11

What is hemianopia?

Answer 11

blindness of one-half of the visual field

Question 12

What is quadrantanopia?

Answer 12

blindness of a quadrant of the visual field

Most common is upper nasal quadrant of one eye and the upper temporal quadrant of the other eye

Question 13

Cant see out of one eye

Answer 13

unilateral lesion of optic nerve = monocular blindess

Question 14

Binasal hemianopia

Answer 14

bilateral lesion of lateral aspect of the optic chiasma

Heteronymous blindness in nasal fields of each eye

Question 15

Unilateral nasal hemianopia frequently due to what?

Answer 15

atherosclerosis of the internal carotid arteries
Lateral aspect of optic chiasma necrosis
Nasal hemianopia of the ipsilateral eye

Question 16

describe right hemianopia of the left eye

Answer 16

blindness of right visual field (nasal field) of the left eye
Due to lesion of lateral aspect of the left optic chiasma

Question 17

Bitemporal hemianopia

Answer 17

Midline lesion of medial portion of the optic chiasma

Heteronymous deficit usually caused by pituitary tumors

Question 18

Contralateral homonymous heminaopia

Answer 18

unilateral lesions of the lateral geniculate body, complete optic radiations, or visual cortex

Cut on right side = left visual field gone

Question 19

Contralateral superior quadrantanopia

Answer 19

Unilateral lesions of the loop of Meyer
Tumor in posterior temporal lobe

Left Superior quadrant gone = right loop of Meyer lesion

Question 20

Incongruent contralateral homonymous hemianopia with macular sparing

Answer 20

unilateral lesion of the visual cortex

Obstruction of PCA

Question 21

What optic reflex does tabes dorsalis/ syphilis interrupts?

Answer 21

light reflex

Pretectum interference

Question 22

What Optic reflex does horner’s syndrome interrupt?

Answer 22

sympathetic neurons to cause pupillary dilator mm to dilate pupil

Question 23

What type of response is accommodation?

Answer 23

cortically mediated visual respone

Question 24

What is the triad of accommodation?

Answer 24

convergence of vision, pupillary constriction and thickening of the lens

Question 25

What is Argyll-Roberston pupil?

Answer 25

result of syphilis infection
Pupils unreactive to light but constrict during accommodation

Destruction of pretectum

Question 26

What is Holmes-Adie pupil

Answer 26

lesion of ciliary ganglion

pupils unreactive to light but slow to react to accommodation