Visual System

Front 1

What are the anterior and posterior chambers of the eye?

Back 1

Primary aqueous humor filled chambers in front of the lens

Front 2

What is the vitreous body of the eye?

Back 2

Chamber located behind the lens filled with vitreous humor

Front 3

How are images in the visual field focused?

Back 3

Through the cornea, pupil of the iris, lens then on the retina.

Front 4

What is the retina?

Back 4

Neural part of the eye that converts a visual image into nerve action potentials through an energy requiring chemical process

Front 5

Describe the layers of the retina

Back 5

7-10 layers of neuroglial cells and cell processes

Front 6

How are images transduced?

Back 6

Photoreceptors - divided into rods and cones

Front 7

Describe the function of photoreceptors

Back 7

Contain pigments that can be altered very rapidly by light to generate a depol of a nerve cell membrane

Front 8

Describe Rods

Back 8

Approx. 130 million per eye Sensitive to dim light and cannot differentiate color Rhodospin (Vit A)

Front 9

What can result if there is a loss of rods? \

Back 9

Night blindness - "legally blind"

-Can be due to Vit A insufficiency

Front 10

Describe Cones

Back 10

Approx. 7 million per eye Sensative to different frequencies associated with red,blue, green :lodopsins

Front 11

How is color perceived

Back 11

As combinations of different cone types activation

Front 12

What can occur in the absence of one of the photopigments of cones?

Back 12

Color blindness - usually red and green

Front 13

Why is color blindness more common in men?

Back 13

Because genes encoding the red or green pigments is on the X chromosome

Front 14

Where are cones most numerous?

Back 14

The Fovea

Front 15

What is the Fovea?

Back 15

Small depression in the retina in whch the primary visual image is focused

Front 16

In primates what makes up most of the fovea?

Back 16

Cones .

Front 17

What is the Fovea?

Back 17

Region of the eye with the highest visual acuity

Front 18

What retinal layers are present in the fovea?

Back 18

Photoreceptors containing cones

Front 19

True or false: Retinal vessels are present on the fovea

Back 19

False: Retinal Vessels are ABSENT on the fovea

Front 20

What is the Macula

Back 20

Area surrounding the fovea that has a yellowish appearance due to the presence of yellow pigment

Front 21

What may result in severe visual impairment (in relation to the macula)

Back 21

Macular Degeneration - Unknown Origin

Front 22

How is visual information received?

Back 22

Photoreceptors generate electrical potentials that are processed in the retina and finallt conducted out of the eye as action potentials by Retinal Ganglion Cells

Front 23

What do the axons of the Retinal ganglion cells form?

Back 23

Optic nerve, chiasm, and optic tracts

Front 24

What is the Optic disc

Back 24

Papilla

Point at which retinal ganglion cell axons leave the eye and retinal blood vessels enter.

Front 25

What forms the blind spot in the visual field?

Back 25

Lack of photo receptors in the Optic disc

Front 26

Why is the optic disc examined after head trauma?

Back 26

It can indicate the presence of increased intracranial pressure from hydrocephalus

Front 27

What is Papilledema

Back 27

Blockage of flow from retinal veins leading to swelling of the optic nerve head.

Front 28

What is Glaucoma

Back 28

Increased pressure from the fluid chambers of the eyes

Front 29

What is a visual fields

Back 29

What you can or cannot see with each eye

Front 30

What is Perimerty

Back 30

Quantitation of visual field

Front 31

How is Perimetry testing done?

Back 31

Usually done with a machine that shows brief flashes of light at different points within the visual field as the patient looks at a central point.

Front 32

How are visual fields usually represented?

Back 32

Graphically as two circles.

Blind spot and macula may or may not be shown

Front 33

How do axons from the retinal ganglion cells travel from the retina?

Back 33

Through the optic nerve to the optic chiasm.

Front 34

At the optic chasm where do the axons of the retinal ganglion cells travel?

Back 34

Half carry info from the retina of each eye cross, thereby dividing the visual field into halves - vertically

Front 35

Which hemispheres does each visual field get routed to?

Back 35

Right half of visual field to the left hemisphere

Left half of visual field to the right hemisphere

Front 36

What is binocular vision

Back 36

Depth Perception

Front 37

What creates depth perception?

Back 37

The division of the visual fields into left and right halves and the fact that the visual fields from each eye overlap

Front 38

How is a three dimensional perception of space created?

Back 38

By comparing the overlapping images in the occipital lobe

Front 39

How does the optic chiasm axons contact the lateral geniculate nucleus of the thalamus

Back 39

Travels around the brainstem near the crus cerebri

Front 40

What does the lateral geniculate nucleus do?

Back 40

Puts together the entire left or right visual field from both eyes

Front 41

What is the geniculo-calcarine tract?

Back 41

Where the lateral geniculate neurons project to primary visual cortex in the occipital lobe

Front 42

Where is the primary visual cortex located?

Back 42

On either side of the calcarine sulcus of the occipital lobe

Posterior cerebral artery territory)

Front 43

How is the macula and retina respresented

Back 43

Posteriorly and the surrounding retina more anteriorly

Front 44

Vision loss in one eye due to

Back 44

Lesion of the optic nerve

Front 45

Vision loss in both eyes

Back 45

Lesions at or beyond the chiasm

Front 46

Lesion including the primary visual cortex will produce

Back 46

Contralateral hemianopsia with macular sparing

Front 47

Why is the macula spared with a lesion of the primary visual cortex?

Back 47

Because of some collateral circulation from the middle cerebral arteries

Front 48

What is the pupillary light reflex

Back 48

Basic clinical test for visual function, where a light is shined in one eye and observed for pupillary constriction

Front 49

What is involved in the pupillary light refelx

Back 49

Ciliary ganglion, oculomotor nerve, optic nerve and some nuclei in the brainstem near the superior colliculus of the tectum.

Front 50

What can cause the disruption of the pupillary light reflex?

Back 50

Disruption of any of the pathways involved in the reflex

Front 51

What occurs to the light reflex if the optic nerve is disrupted

Back 51

A light shined into the blind eye will not produce constriction, but will when shined into the normal eye

-Swinging the light back to the blind eye will then result in dilation of both pupils

Front 52

What is the most common impairment of the pupilary reaction to light?

Back 52

Deteriorating conscious level after head injury

Front 53

When will the uninjured side eye still respond to light reflex?

Back 53

As long as the optic pathway is intact

Front 54

What controls pupillary dilation?

Back 54

Sympathetic nervous system