Choroid

Question 1

What are the three things that make up the uvea?

Answer 1

• choroid
• ciliary body
• iris

Question 2

The choroid extends from what to what? And lies between what two structures?

Answer 2

• extends from the ora-serrate to the optic nerve

- lies between the sclera and the retina

Question 3

What is the ora-serrata?

Answer 3

• tapering of the retina and the choroid.
• the two layers stop at this point and from that point forward is known as the ciliary body.
• point at which the retinal pigmented epithelium becomes pigmented ciliary epithelium

Question 4

What does the choroid mostly consist of ?

Answer 4

Blood vessels to supply the outer retinal layers

Question 5

What supplies the inner retinal layers?

Answer 5

Central retinal artery

Question 6

What is the connective tissue between the sclera and the choroid?

Answer 6

-suprachoroid

Question 7

What is the connective tissue between choroid and retina?

Answer 7

Bruch’s membrane

Question 8

What are the layers of the choroid from Superficial (scleral) to deep (retina)?

Answer 8

• suprachoroid lamina
• choroidal Stroma
• Choriocapillaris
• Bruch’s membrane

Question 9

The suprachoroid lamina is a hybrid zone meaning what?

Answer 9

-it contains components from sclera (collagen and fibroblasts) and choroid( melanocytes)

Question 10

The looseness of the suprachoroid lamina allows for what?

Answer 10

-swelling of the vascular net without causing detachment

Question 11

The suprachoroid also space carries what structures?

Answer 11

-carries long posterior ciliary arteries and nerves from posterior to anterior globe

Question 12

What kind of cells are in the choroidal stroma?

Answer 12

• melanocytes
• fibroblasts
• macrophages
• lymphocytes
• mast cells

Question 13

How are the collagen fibrils arranged in the choroidal stroma?

Answer 13

-collagen fibrils are arranged circularly around the vessels (branches of short posterior ciliary arteries)

Question 14

What are the three vessel layers of the choroidal stroma?

Answer 14

• haller’s layer
• sattler’s layer
• capillary bed

Question 15

The deeper you go into the stroma, what happens to the size of the vessels?

Answer 15

-the deeper you go, the smaller the vessels get

Question 16

What is the most superficial layer of vessels in choroidal stroma? Middle? Deepest? Talk about their size too

Answer 16

1. Haller’s layer-largest lumina
2. Sattler’s layer-middle
3. Capillary bed-smallest, closest to retina

Question 17

The veins in the stroma are different because of what characteristic? They also join together to exit the choroid as what veins?

Answer 17

• choroidal veins have no valves

- they join to make vortex veins

Question 18

Describe the sympathetic innervation of the choroidal stroma

Answer 18

• vasoconstriction and decreased choroidal blood flow

- comes from sympathetic trunk of carotid plexus via ciliary ganglion

Question 19

Describe the parasympathetic innervation of choroidal stroma

Answer 19

• vasodilation and increased choroidal blood flow

- comes from division of CN III via ciliary ganglion

Question 20

Both parasympathetic and sympathetic systems use what nerves to innervate the choroidal stroma?

Answer 20

Short ciliary nerves

Question 21

What is the choriocapillaris layer?

Answer 21

• specialized capillary bed

- single layer of anastomoses, fenestrated capillaries with wide lumina

Question 22

In the choriocapillaris, what direction do most fenestrations face?

Answer 22

Face towards the retina

Question 23

Why is the size of the lumen in choriocapillaris important?

Answer 23

-it is larger than normal capillaries so blood cells can pass through side by side instead of a single file line like normal capillaries

Question 24

What is the function of pericytes in the choriocapillaris?

Answer 24

-contractile function to alter local blood flow

Question 25

Where is the choriocapillaris the densest? Why?

Answer 25

In the macular area because it is the sole blood supply for that region of the retina

Question 26

Does the choriocapillaris continue into the ciliary body?

Answer 26

Nah

Question 27

What is the course of Bruch's membrane?

Answer 27

- from optic nerve to ora serrata | - undergoes some modification before continuing into the ciliary body

Question 28

Name the layers of Bruch's membrane from superficial to deep

Answer 28

- basement membrane of choriocapillaris - outer collagenous zone - elastic layer - inner collagenous zone - basement membrane of RPE cells

Question 29

What contributes to the tight adhesion of choroid and outer pigmented layer of the retina?

Answer 29

-fine filaments from basement membrane to RPE merge with inner collagenous zone

Question 30

What is the functional/histological change at the ora serrata

Answer 30

- basement membrane of RPE becomes continuous with basement membrane of pigmented epithelium of the ciliary body - collagenous and elastic layers of bruch's membrane disappear into the stroma - basement membrane of the choriocapillaris continues as basement membrane of ciliary body capillaries

Question 31

What are the functions of the choroid?

Answer 31

1. Provides nutrient to outer retina and lets catabolites pass from retina to choriocapillaris 2. Dark pigment absorbs light like the RPE layer 3. Suprachoroid space lets posterior vessels and nerves go through to supply anterior globe

Question 32

What provides sensory innervation for the uvea?

Answer 32

-nasociliary branch off V1

Question 33

What nerve innervates choroidal blood vessels (sympathetic) and what nerve innervates iris dilator and ciliary muscles (sympathetic)

Answer 33

- short posterior ciliary nerves | - long ciliary nerves

Question 34

What ganglion has parasympathetic fibers for the ciliary muscle, iris sphincter, and choroidal vessels?

Answer 34

Ciliary ganglion

Question 35

What are drusen?

Answer 35

-as we age, excessive basement membrane material is deposited in the collagenous zones (inner) of Bruch's membrane

Question 36

Where are drusen located? What do they contain? What do they do to the retina?

Answer 36

- contain cellular fragments and an accumulation of basal laminar material - located outer to the RPE basement membrane and displace the retina inward