Aging Changes, Function, and Blood Supply to the Vitreous

Question 1

in an infant, the vitreous chamber looks like what?

Answer 1

Very homogenous, gel-like body. Chamber appears optically empty. May be able to see vitreous cortex because collagen is so dense there.

Question 2

With age, the gel volume decreases and the liquid volume increases due to ___

Answer 2

A loss of hyaluronic acid and redistribution of collagen. This happens quicker in myopes. This mostly occurs in central vitreous where the collagen concentration is lowest.

Question 3

Without as much hyaluronate with age, what happens to collagen?

Answer 3

Hyaluronate helped keep spacing between the collagen. Without it, the collagen will clump together into bundles. They can be seen as white strands and are visible to pts as floaters as they will cast shadows on the retina.

Question 4

Liquid vitreous pools between collagen bundles forming

Answer 4

Lacunae

Question 5

Term used to describe gel decrease and liquid increase in the vitreous

Answer 5

Liquefaction or virtual syneresis

Question 6

By age 40, the vitreous is __% gel and __ % liquid

By age 80, the vitreous is __% gel and __% liquid

Answer 6

80 gel, 20 liquid

50 gel, 50 liquid

Question 7

In what percent of patients can liquefaction eventually lead to a PVD?

Answer 7

1%

Question 8

What to tell patients if they come in complaining of annoying floaters?

Answer 8

Surgery is risky. They may eventually settle to the bottom of the eye due to gravity or the brain will learn to ignore them.

Question 9

5 main functions of the vitreous

Answer 9

1. Transmits and refracts light, aiding in the focusing light rays on the retina.
2. Shock absorber
3. Diffusion barrier between anterior and posterior segments
4. MAY hold retina in place next to RPE (little significance since RPE stays in place if pt has vitrectomy)
5. Store metabolites for retina such as ascorbate (little significance)

Question 10

Why can you not use an eye drop to treat the retina?

Answer 10

Will not be able to reach the retina since it will not be able to diffuse through the vitreous. Serves as a barrier.

Question 11

Blood supply to the vitreous

Answer 11

Avascular due to very few cells and no regeneration of collagen. Little metabolic activity in the vitreous.

Receives nutrition from ciliary body and inner retina.