The Eye - Retina

Question 0

Where is photosensitve retina found?

Answer 0

Lining the posterior portion of the eye

Question 1

What does the retina line?

Answer 1

Neuro-epithelial structure that lines the entire inner surface of the globe except for the anterior chamber

Question 2

What is the ora serrata?

Answer 2

The transition between the multi-layered photosensitive retina and the bi-layer of retina that lines the inner surface of the ciliary body and the posterior margin of the iris

Question 3

What is retina proper?

Answer 3

The photosensitive neural retina

Question 4

Where is pigmented epithelium located in the retina?

Answer 4

Lining the ciliary body and the iris, non-photosenstive

Question 5

What is the fovea?

Answer 5

Site of most acute vision in the retina

Question 6

What is the optic disk?

Answer 6

Also called the papilla and is the exit of the optic nerve (blind spot)

Question 7

Embryologically, from where is the retina derived?

Answer 7

From the brain, specifically the optic vesicle.

Question 8

What is the optic vesicle

Answer 8

Grows out of the diencephalon of the brain essentially as a neuroepithelial sphere and when extending and reaching the anterior body surface it invaginates forming a double walled cup

Question 9

Outer layer of the walled cup during development becomes? Inner layer?

Answer 9

Outer layer is the pigmented epithelium

Inner layer is the photosesitive retina.

Question 10

What forms around the double walled cup?

Answer 10

The CT that will produce the uvea and cornea-sclera

Question 11

Describe the pathway of light to the retina

Answer 11

Cornea, anterior chamber, lens, vitreous body, then retina. 8 layers of retina before reaching the photosensitive layer of receptor cells

Question 12

T or F: Our eyes are inside out compared to other animals like the cephalopods

Answer 12

T

Question 13

Pigmented epithelium is found?

Answer 13

Internal covering of the ciliary body and iris, also external to the photosensitive retina. Not photosensitive

Question 14

From the posterior most portion of the eye, what are the layers of retina?

Answer 14

1. Pigmented epithelium
2. Receptor layer
3. External limiting membrane
4. Outer nuclear layer
5. Outer plexiform layer
6. Inner nuclear layer
7. Inner plexiform layer
8. Ganglion cell layer
9. Optic nerve fiber layer
10. Internal limiting membrane

Question 15

Function of layer 1 (outermost layer of retina, i.e. last layer of interaction with light)

Answer 15

Pigmented epithelium (outer wall of double walled cup). ONly layer derived from the outer wall cup

Question 16

Layer 2

Answer 16

Receptor layer with the photosensitive parts of neuroepithelial rods and cones

Question 17

Layer 3

Answer 17

External limiting membrane, region of intercellular junctional complexes

Question 18

Layer 4

Answer 18

Outer nuclear layer where the cell bodies of nuclei of the rods and cones

Question 19

Layer 5

Answer 19

Outer plexiform layer consisting of synaptic connections between the receptor cells (rods and cones) and some inter-nerons, primarily bipolar and horizontal cells.

Question 20

Layer 6

Answer 20

inner nuclear layer, layer of cell bodies and nuclei of bipolar neurons and other inter-neurons

Question 21

Layer 7

Answer 21

Inner plexiform layer, another layer of synaptic connections between the bipolar cells, some amacrine cells, and the dendrites of retinal ganglion cells

Question 22

Layer 8

Answer 22

Ganglion cell layer, the layer of cell bodies and nuclei of neurons whose axons form the optic nerve

Question 23

Layer 9

Answer 23

The optic nerve fiber layer which contains the axons of retinal ganglion cells as they gather to form the optic nerve

Question 24

Layer 10

Answer 24

Internal limiting membrane, basically the end processes of the glial-like supporting Muller cells and the basement membrane of the retinal neuroepithelium

Question 25

What layer does light first enter in the retina?

Answer 25

Layer 10, the internal limiting membrane

Question 26

Where is the synaptic zone of bipolar neurons and dendrites of ganglion cells?

Answer 26

Layer 7, the inner plexiform layer

Question 27

Where are ganglion cells in the retina?

Answer 27

Layer 8, the ganglion cell layer

Question 28

Where are rods and cones?

Answer 28

Layer 2, the receptor layer

Question 29

Where are the cell bodies of the rods and cones?

Answer 29

The outer nuclear layer, layer 4

Question 30

Rods and cones are stimulated by light and then?

Answer 30

Synapse with bipolar cells which synapse with retinal ganglion cells, the axons of which form the optic nerve

Question 31

Which layer do bipolar nerves synapse with receptor rods and cones?

Answer 31

At the Layer 5, Outer plexiform layer

Question 32

Rods and cones and their photosensitive elements extend and are embedded partially within the?

Answer 32

Pigmented epithelial layer which is important as the pigmented epithelial cells phagocytosis cast off receptor elements of rods and cones

Question 33

Describe photoreceptors

Answer 33

Consists of outer and inner segments as well as cell body

Photosensitive rhodopsin is located in the outer segments

Question 34

What is the outer segment of the rods/cones?

Answer 34

The apical region of the cell and contain complex foldings of plasmalemma that contain the photosensitive proteins

Question 35

Two types of photoreceptors and function

Answer 35

Rod cells - mediate vision in dim light, detect motion

Cone cells - differentiate between different wavelengths of light and are used for color vision, daylight vision

Question 36

Where are rods found?

Answer 36

more numerous than cones and are found in greatest concentration about 20 degrees off the foveal axis

Question 37

Where are cones found?

Answer 37

Almost exclusively in a narrow region around the fovea. Around the middle posterior of the eye

Question 38

Where are neither rods or cones found?

Answer 38

The blind spot, where the optic nerve is. A little less than 20 degrees counterclockwise fro the middle posterior of the eye

Question 39

What is the fovea centralis?

Answer 39

The site of concentration of cone receptor cells and site of most acute vision. Manifests as a small impression in the retina just lateral to the optic disk

Question 40

How does the fovea attain increased acuity?

Answer 40

The top layers are displaced laterally allowing light more direct access to photoreceptors
Contains the highest density of cone photoreceptors

Question 41

What is the optic nerve?

Answer 41

Composed of the axons of the ganglion cells that transverse the inner layer of the retina to form the optic nerve at the optic disk.

Question 42

Where does the optic nerve leave the eye?

Answer 42

At the optic disk (papilla), no photoreceptors there

Question 43

What is a detached retina?

Answer 43

Result of traumatic injury and allows fluid to get in between the layers of the eye wall pushing the retina away from the focal plane of eye. Separation of the neural retina and the pigmented epithelium

Question 44

What is diabetic retinopathy?

Answer 44

Most common diabetic eye disease and can result in blindness.
Results from hyperglycemia killing pericytes around capillaries and making basement membranes thicker thus leading to weakening of capillary walls and thus permeability. Lack of oxygen in tissue, leads to new capillaries forming over the surface of the retina and will lead to blind spots and finally small hemorrhages. Occurs in 20-40% of diabetics.

Question 45

What is hypertensive retinopathy?

Answer 45

Results from vessel change to adapt to increased pressure by hardening. Extremely common and difficult to distinguish from other types
Occurs in 3-14% of adults over 40 yoa.