Visual Tracts

Question 1

What are the three layers present in the eye?

Answer 1

Fibrous layer, vascular layer, and retina

Question 2

What are the components of the fibrous layer?

Answer 2

Sclera and cornea

Question 3

What are the components of the vascular layer?

Answer 3

Choroid, ciliary body, and iris

Question 4

What does the retina give rise to?

Answer 4

The optic nerve

Question 5

What is the sclera comprised of and what is its role?

Answer 5

Dense regular CT with flat bundles of type I collagen. Sclera is insertion site for extraocular muscles

Question 6

What are the layers of the cornea?

Answer 6

Corneal epithelium, anterior limiting membrane (Bowman membrane), stroma, posterior limiting membrane (Descemet’s membrane), inner endothelium

Question 7

What is the stroma comprised of?

Answer 7

Keratocytes

Question 8

What kind of epithelium is corneal epithelium made of?

Answer 8

Nonkeratinized stratified squamous

Question 9

What is the limbus?

Answer 9

The area where the transparent cornea merges with the opaque sclera. This is where the Bowman’s membrane ends and the conjunctiva begins.

Question 10

What is the choroid made of?

Answer 10

Loose, well-vascularized connective tissue and contains numerous melanocytes (black appearance).

Question 11

What is the Bruch membrane?

Answer 11

It is a thin extracellular sheet that includes the basal lamina of the retina’s pigmented layer.

Question 12

What are the two layers of the retina and what epithelium are they?

Answer 12

Outer pigmented layer - simple cuboidal epithelium

Inner neural layer - thick and stratified with various neurons and photoreceptors.

Question 13

What does the neural layer of the retina extend to anteriorly?

Answer 13

The ora serrata

Question 14

What is the pigmented epithelium?

Answer 14

It is a layer of cuboid cells that surround the neural retina

Question 15

What are the layers of the neural retina?

Answer 15

Inner limiting membrane, nerve fiber layer, ganglionic layer, inner plexiform layer, inner nuclear layer, outer plexiform layer, outer nuclear layer, outer limiting layer, rod and cone layer , pigmented layer

Question 16

What does the inner segment of the rod contain?

Answer 16

Glycogen, mitochondria, and polyribosomes.

Question 17

What are stacked like coins in the outer segment of the rods?

Answer 17

Flattened membranous discs

Question 18

What is located within the membranous discs?

Answer 18

Rhodopsin

Question 19

What visual pigment is located in the cones?

Answer 19

Iodopsin

Question 20

What is the macula lutea?

Answer 20

The area that surround and protects the cones in the fovea centralis

Question 21

What is the optic disc?

Answer 21

Where the ganglion axons from all of the retinal converge and form the optic nerve.

Question 22

Where does the optic tract lead to?

Answer 22

The lateral geniculate nucleus (LGN)

Question 23

What are the outgoing fibers from the LGN?

Answer 23

Optic radiations

Question 24

Where is the primary visual cortex located?

Answer 24

Lower and upper banks of the calcarine sulcus

Question 25

What does the lower quadrant of the contralateral hemifield relay to?

Answer 25

The superior bank of the sulcus, the cuneus

Question 26

What is the path of photons from the upper quadrant of the contralateral hemifields?

Answer 26

Arch rostrally, pass through the temporal lobe, do a broad U-turn, the Meyer loop –> inferior bank of the sulcus, the lingual gyrus

Question 27

What is the role of the visual association cortex and where is it located?

Answer 27

Helps interpret location, motion, form, and color. It is located in the parieto-occipital-temporal area.

Question 28

What is the role of the superior colliculus related to the eyes?

Answer 28

It is important in directing eye movements

Question 29

What is the role of the pretectal area related to the eyes?

Answer 29

It is important for the pupillary reflex

Question 30

What is Hemianopia?

Answer 30

Blindness in one half of the visual field

Question 31

What is Quadrantanopia?

Answer 31

Blindness of a quadrant of the visual field

Question 32

What is homonymous visual fields?

Answer 32

Conditions in visual field losses are similar in both eyes

Question 33

What is heteronymous visual fields?

Answer 33

Conditions in which the two eyes have non-overlapping field losses

Question 34

What is macular sparing?

Answer 34

Visual field loss that preserves vision in the center of the visual field.

Question 35

What is a congruous deficit?

Answer 35

A deficit that causes a symmetrical visual field loss in both eyes. This is more common in lesions that occur closer to the visual cortex

Question 36

What is an incongruous deficit?

Answer 36

A deficit that is asymmetrical in both eyes. Usually occurs when the lesion is more anterior, closer to the eyes.

Question 37

What does damage anterior to the optic chiasm cause?

Answer 37

Effects of the ipsilateral eye

Question 38

What does damage at the optic chiasm cause?

Answer 38

Heteronymous deficits

Question 39

What does damage behind the optic chiasm cause?

Answer 39

Homonymous deficits

Question 40

What is associative visual agnosia, what causes it, and what are the effects of it?

Answer 40

It is a deficit that disconnect the language area from the visual association cortex. It is typically causes by PCA damage. Patients cannot name or describe an object in the visual field, BUT they can recognize and demonstrate its use. Patients may also present with alexia or agraphia.