Vitreous/Retina/Choroid

Question 1

What tunic of the eye delivers nutrients to the outer retina?

Answer 1

Choroid

Question 2

Where is the choroid thickest?

Answer 2

Nasal and temporal to the fovea

Question 3

What is the average thickness range of the choroid?

Answer 3

500-2500 microns

Question 4

What is the name of the specialized capillary bed that is the sole blood supply to the macula?

Answer 4

Choriocapillaris

Question 5

What is “special” about the choriocapillaris?

Answer 5

Fenestrated with capillaries that are 3-4x wider than normal

Question 6

How are collagen fibers arranged around the vessels in the choroidal stroma?

Answer 6

Circularly around the vessels

Question 7

What is the blood supply to the choroid?

Answer 7

Branches of the short posterior ciliary arteries

Question 8

What is the venous drainage of the choroid?

Answer 8

Venules to the vortex veins

Question 9

What is the innervation of the choroid?

Answer 9

Nasociliary branch of the trigeminal nerve

Question 10

What are the sympathetics to the choroid?

Answer 10

From superior cervical ganglion, via the ophthalmic and short ciliary nerves

Question 11

What does Bruch’s membrane fuse with?

Answer 11

Retina

Question 12

What is the course of Bruch’s membrane?

Answer 12

Optic nerve to ora; is modified, and continues into the ciliary body

Question 13

What are the layers of the choroid from inner to outer?

Answer 13

Bruch’s membrane
Choriocapillaris
Sattler’s layer, Haller’s layer
Suprachoroidal lamina

Question 14

What is found in the choroidal stroma?

Answer 14

Loose CT
Melanocytes
Fibroblasts
Macrophages
Lymphocytes
Mast cells

Question 15

The vitreous makes up what percentage of the eye?

Answer 15

80%

Question 16

The vitreous only interfaces with what?

Answer 16

Basement membranes

Question 17

What are the 5 attachments of the vitreous from strongest to weakest?

Answer 17

1. Vitreous base
2. Posterior lens
3. Optic disc
4. Macula
5. Retinal vessels

Question 18

What is the vitreous base?

Answer 18

Vitreal fibers embedded in the basement membrane of the nonpigmented epithelium of the ciliary body and ILM of retina

Question 19

What is the extent of the vitreous base?

Answer 19

3mm anterior to ora, 1-3mm posterior to ora, and several mm into the vitreous

Question 20

What is the location of the anterior hyaloid?

Answer 20

Vitreous base to posterior capsule of the lens

Question 21

What is the location of the posterior hyaloid?

Answer 21

Posterior end of the vitreous base to the optic disc

Question 22

What is the vitreous cortex made of?

Answer 22

Tightly packed collagen fibrils; some parallel, and some perpendicular to the retina

Question 23

What is another name for Cloquet’s Canal?

Answer 23

Hyaloid canal

Question 24

Where does the hyaloid canal terminate?

Answer 24

Area of Martegiani

Question 25

What is the area of Martegiani?

Answer 25

Funnel shaped space at the optic nerve head that extends into the vitreous

Question 26

What are the layers of the retina from outside to inside?

Answer 26

``` RPE PRs External limiting membrane Outer nuclear layer Outer plexiform layer Inner nuclear layer Inner plexiform layer GC layer NFL Internal limiting membrane ```

Question 27

How many PRs does a single RPE cell interact with?

Answer 27

30-40

Question 28

How many cells thick is the retinal RPE layer?

Answer 28

1

Question 29

How many total RPE cells are there?

Answer 29

4-6 million

Question 30

What is contained in the PR layer of the retina?

Answer 30

Inner and outer segments of the rods and cones

Question 31

Projections from what also extend into the PR layer, and separate the inner segments?

Answer 31

Apical surface of Muller cells

Question 32

What makes up the external limiting membrane?

Answer 32

Zonula adherens between PRs, and between PRs and Muller cells

Question 33

What makes up the outer nuclear layer?

Answer 33

Cell bodies of rods and cones

Question 34

Where is the outer nuclear layer the thickest?

Answer 34

Fovea

Question 35

How many cells thick is the outer nuclear layer on the nasal edge of the disc?

Answer 35

8-9 cells thick

Question 36

How many cells thick is the outer nuclear layer at the temporal edge?

Answer 36

4 cells thick

Question 37

What is found in the outer plexiform layer?

Answer 37

Synapses of PRs with bipolar cell dendrites and horizontal cell processes

Question 38

What is found in the inner nuclear layer?

Answer 38

Cell bodies of horizontal cells, bipolar cells, amacrine cells, muller cells, and interplexiform cells

Question 39

What is found in the inner plexiform layer?

Answer 39

Synapses between bipolar cells axons and ganglion cell dendrites

Question 40

How thick is the ganglion cell layer?

Answer 40

Single cell, except near the macula

Question 41

What makes up the NFL?

Answer 41

Axons of the ganglion cells

Question 42

What makes up the internal limiting membrane?

Answer 42

Footplates of Muller cells, covered by basement membrane

Question 43

What are the 4 main functions of the vitreous?

Answer 43

Physical support of retina Storage area for metabolites for the retina Shock absorber Refracts light

Question 44

What makes up the vitreous?

Answer 44

Salts, soluble proteins, hyaluronic acid, collagen, mostly water (98-99%)

Question 45

The vitreous contains a lot of ___ which may help regulate oxygen, and prevent oxidative changes to the lens.

Answer 45

Ascorbate

Question 46

By age 40, what percent of the vitreous is still a gel?

Answer 46

80%

Question 47

By age 70-80, what percent of the vitreous is still a gel?

Answer 47

50%

Question 48

Which layer of the choroid contains the largest blood vessels?

Answer 48

Haller's layer