Retinal/Choroid Vascular Physiology (F)

Question 1

What is the vasculature that forms from the optic nerve head? 1. What do the vertical sprouts from the superficial plexus give rise to? 2

Answer 1

1. primary vascular plexus

2. inner capillary plexus

Question 2

Where do long and short posterior ciliary arteries first coalesce?

Answer 2

mesenchymal meshwork adjacent to the primitive RPE

Question 3

When does substantial interarterial anasamosing occur during development?

Answer 3

4th month

Question 4

What does the ophthalmic artery split into that supply the eye?

Answer 4

1. central retinal artery (CRA, 2)

2. ciliary arteries (CA, 3)

Question 5

What artery provide oxygen and nutrients to the inner retina?

Answer 5

central retinal artery

Question 6

What arteries providesoxygen and nutrients to the RPE and outer retina (photoreceptors)?

Answer 6

ciliary arteries

Question 7

Are retinal vessels innervated? 1. Is the choroid? 2

Answer 7

1. no

2. yes

Question 8

What is the percentage of O2 is delivered to the retina by the choroid? 1. Percentage of glucose? 2. Percentage of blood flow? 3

Answer 8

1. 65%
2. 75%
3. 4%

Question 9

What is the percentage of O2 is delivered to the retina by the choroid? 1. Percentage of glucose? 2. Percentage of blood flow? 3

Answer 9

1. 65%
2. 75%
3. 4%

Question 10

How is the foveola nourished?

Answer 10

through choroid only

Question 11

What cells are tight junctions found in regards to the blood vessels of the retina?

Answer 11

endothelial cells

Question 12

What is the superficial glia sheathed by? 1. What are the inner plexuses sheathed by? 2

Answer 12

1. astrocytes

2. Muller cells

Question 13

Are blood vessels of the choriocapillaris fenestrated?

Answer 13

yes

Question 14

What are transported via transcellular mechanisms in the RPE?

Answer 14

nutrients and vitamin A

Question 15

What mediates glucose transport (transcellularly) into retinal vasculature endothelial cells? 1. Where are these located? 2

Answer 15

1. GLUT1

2. luminal and abluminal membranes

Question 16

What are the major complications are associated with pathology of the inner retina and inner blood-retinal barrier?

Answer 16

1. Loss of pericytes, and capillaries
2. Increased tortuosity of retinal capillaries
3. Microaneurysms
4. Plasma protein leakage
5. Neovascularization (advanced)

Question 17

What is it called when the retina of premature infants are exposed to excess O2?

Answer 17

retinopathy of prematurity

Question 18

What is it called when the retina of premature infants are exposed to excess O2?

Answer 18

retinopathy of prematurity (abnormal vascularization)

Question 19

What is 90% of total glucose utilized by retina converted to?

Answer 19

lactate

Question 20

Does the retina have higher metabolism in the light or dark?

Answer 20

dark

Question 21

What is blood flow in the retina and choroid a function of?

Answer 21

muscular tonus of the arterioles and the state of contraction of the pericytes (because no sphincters)

Question 22

What does an increase in lactate lead to?

Answer 22

Vasodilatory response

Question 23

What does an increase in lactate lead to?

Answer 23

Vasodilatory response

Question 24

What determines if light induces vasodilation or vasoconstriction?

Answer 24

presence of nitric oxide

Question 25

What is a reduction in blood oxygen that preferentially affects the outer retina?

Answer 25

hypoxia

Question 26

What does hypoxia cause in the retina? 1. How does it do this? 2

Answer 26

1. Causes vasodilation in the retina and increases blood flow 2. Due to release of retinal lactate and endothelium derived nitric oxide

Question 27

What does hyperoxia cause in the retinal arterioles? 1. In the choroid? 2. What mediates these responses? 3

Answer 27

1. Causes vasoconstriction of the retinal arterioles 2. Choroidal blood flow does not change with increase in pO2 3. ET-1 receptors (endothelin -1) in the retina

Question 28

What does hypercapnia cause in the retina? 1. In the choroid? 2. What mediates these responses? 3

Answer 28

1. Causes vasodilation in the retina and increases blood flow and decrease pH 2. increases blood flow in the choroid 3. endothelial release of prostaglandins and Nitric oxide

Question 29

What does hypercapnia cause in the retina? 1. In the choroid? 2. What mediates these responses? 3

Answer 29

1. Causes vasodilation in the retina and increases blood flow and decrease pH 2. increases blood flow in the choroid 3. endothelial release of prostaglandins and Nitric oxide

Question 30

What is is the mean blood pressure in the ophthalmic artery minus the blood pressure in the central retinal vein called?

Answer 30

mean perfusion pressure driving blood through the retina

Question 31

What does high IOP cause in the retina?

Answer 31

1. Inner retina pO2 is unaffected due to autoregulation | 2. Outer retina blood flow and pO2 decreases

Question 32

What are the metabolic components that are tone relaxing? 1. Tone contracting? 2

Answer 32

1. lactate, prostaglandins, and nitric oxide | 2. Endothelin-1

Question 33

What are the two mechanisms of production of nitric oxide (and where do each exist)?

Answer 33

1. NOS1 (expressed in retinal neurons = ganglion, amacrine, horizontal, muller, photoreceptors, RPE) 2. NOS3 (endothelial cells of the retina and choroidal vessels and pericytes of the retinal capillaries, and endothelium of optic nerve head)

Question 34

Where is Endothelin-1 expressed in the eye?

Answer 34

endothelium, retinal neurons, astrocytes, and pericytes

Question 35

What are prostaglandins mediated by?

Answer 35

adenyl cyclase and inhibition of calcium flux in smooth muscle cells

Question 36

What are prostaglandins mediated by?

Answer 36

adenyl cyclase and inhibition of calcium flux in smooth muscle cells

Question 37

What does sympathetic innervation do to the choroidal blood flow? 1. What is it mediated by? 2. What is it stimulated by? 3

Answer 37

1. reduces choroidal blood flow 2. vasoconstrictive alpha-receptors in smooth muscle cells 3. neurotransmitter neuropeptide Y (NPY)

Question 38

What does parasympathetic innervation do to the choroidal blood flow? 1. What is it mediated by? 2. What is it stimulated by? 3

Answer 38

1. increases choroidal blood flow 2. vasodilation 3. acetyl choline, vasoactive intestinal peptide (VIP), PACAP, and NO

Question 39

What acts as a modulator of synaptic transmission in vasodilation in the retina and choroid?

Answer 39

adenosine