What are the physio-chemical properties of vitreous?
PHYSIO-CHEMICAL PROPERTIES OF VITREOUS:
Vitreous is a clear gel like optically empty structure. Its physio-chemical properties are as under:
Weight and Volume
Body weight of vitreous is 4 grams; voluine is 4 cc and is approximately two-third the volume of entire globe.
There is a fine random arrangement of vitreous fibres and high water content. This leads to a gel like fornlatiou having a high transparency.-It is optically empty.
Plasticity of vitreous is due to its three dimensional network of randomly oriented road like collagen fibers. These collagen Fibers are electro-statically neutral and are not cross linked. This property allows vitreous to expand and give it its plastic property.
This property is provided by the presence of hyaluronic acid molecular chains entangled around the collagen fibers. The numerous negatively charged group of hyaluronic acid molecules precipitates extreme volume changes, thus contributing to viscoelasticty.
The combination of collagen fibers and hyaluronic acid furnishes the stability of gel system. The manner in which the collage and hyaluronic acid interact to stabilize the system is termed as frictional interaction.
Vitreous Expansion and Contraction
This properly is a function of ionic charge of the vitreous structure.
Blood Vitreous Barrier
It is a functional term with the inability of the vitreous to equilibrate with the blood and the surrounding fluid.