Vitreous (F)

Question 1

What are the functions of the vitreous?

Answer 1

1. Regulation of eye growth and shape
2. Barrier function to prevent cellular invasion/migration and diffusion of large macromolecules to maintain transparency
3. Lowering the oxygen tension around the lens

Question 2

Where does the gradient of pO2 and glucose decrease in the vitreous?

Answer 2

anteriorly (greater distance from retinal vasculature and diffusion properties of vitreous)

Question 3

What small molecule is especially high in the vitreous?

Answer 3

ascorbate

Question 4

Is the pH of the vitreous low or high?

Answer 4

low

Question 5

What type of collagen makes up 60-75% of total collagen in the vitreous? 1. ~25% of total? 2.

Answer 5

1. II
2. IX
3. V/XI
4. VI

Question 6

What type of collagen is covalently bound to surface of fibrils and links them together and is bound to chondroitin sulfate?

Answer 6

Collagen IX

Question 7

What type of collagen is covalently bound to surface of fibrils and links them together and is bound to chondroitin sulfate?

Answer 7

Collagen IX

Question 8

What two substances make up the bulk of vitreous?

Answer 8

Collagen and Hyaluronate

Question 9

Where is the lowest concentration of collagen?

Answer 9

central vitreous

Question 10

What is the major GAG found in vitreous? 1. What is the other one commonly found? 2

Answer 10

1. hyaluronote

2. condroitin sulfate

Question 11

What are some of the lesser proteins found in vitreous?

Answer 11

1. Fibrillin
2. Opticin (glycoprotein)
3. Versican (proteoglycan)

Question 12

What is the primary vitreous generated from?

Answer 12

mesenchymal cells, optic vesicle and hyaloid vasculature

Question 13

What is the failure of the embryological, primary vitreous and hyaloid vasculature to regress called? 1. What diseases is it associated with? 2

Answer 13

1. Persistent hyperplastic primary vitreous

2. Trisomy 13, Norrie disease, Walker-Warburg syndrome

Question 14

What is the failure of the embryological, primary vitreous and hyaloid vasculature to regress called? 1. What diseases is it associated with? 2

Answer 14

1. Persistent hyperplastic primary vitreous

2. Trisomy 13, Norrie disease, Walker-Warburg syndrome

Question 15

What is the outer part of the vitreous cortex in the posterior hyaloid and the inner limiting membrane of the retina (ILM)?

Answer 15

Vitreoretinal interface

Question 16

What is the vitreoretinal interface mediated by?

Answer 16

opticin protein

Question 17

What are cells with a lobulated nucleus with cytoplasmic projections and a moderate number of mitochondria? 1. Where are they derived? 2

Answer 17

1. hyalocytes

2. bone marrow

Question 18

Where are hyalocytes concentrated in the vitreous?

Answer 18

anteriorly at the vitreous base and posteriorly near the optic disc

Question 19

What are the functions of hyalocytes?

Answer 19

1. Synthesizes extracellular matrix
2. Remodels ECM
3. Can contract the extracellular matrix

Question 20

What are the functions of hyalocytes?

Answer 20

1. Synthesizes extracellular matrix
2. Remodels ECM
3. Can contract the extracellular matrix

Question 21

What mediated the immune privilege of the vitreous? 1. What is this called? 2

Answer 21

1. hyalocytes

2. vitreous cavity associated immune deviation (VCAID)

Question 22

What weakens posterior vitreoretinal adhesions with age? 1. What does this lead to? 2

Answer 22

1. fibrillar aggregation and an accummulation of water between fibrils from a loss of collagen IX
2. Posterior vitreal detachment (PVD)

Question 23

What area has hypocellular gel contraction? 1 What is it stimulated by? 2

Answer 23

1. cortical vitreous

2. TGFβ