Vitreous humour is an inert ,transparent , colourless, jellylike, hydrophilic gel that serves the optical functions and also acts as important supporting structures for the eyeball. The vitreous cavity is bounded by anteriorly by the lens and ciliary body and posteriorly by the retina Its weighs nearly 4g Vitreous is an extacellular material composed of approximately 99 per cent water

1. Vitreous Humour

2. General features
 Vitreous humour is an inert ,transparent , colourless, jellylike, hydrophilic gel
that serves the optical functions and also acts as important supporting
structures for the eyeball.
 The vitreous cavity is bounded by anteriorly by the lens and ciliary body and
posteriorly by the retina
 Its weighs nearly 4g
 Vitreous is an extacellular material composed of approximately 99 per cent
water

3. Structure
 The vitreous body is the largest and simplest connective tissue present as a
single piece in the human body
 Divided into three parts-
1. The hyaloid layer or membrane
2. The cortical vitreous and
3. The medullary vitreous

4. 1.Hyaloid layer
 It is not a true membrane but the outermost surface of vitreous
 It has a structure of connective tissue and shows fibrils which run parallel
with the surface
 It has two layers
1.Anterior hyaloid membrane
2. Posterior hyaloid membrane

5. 2.Cortical vitreous
 It lie in peripheral zone approx 100 micron in width
 It is more condensed fibrillar vitreous
 It contain type two collagen fibrils interspersed with the sodium
hyaluronate mucopolysaccharides molecules , which provides a viscosity,
and elasticity
 2 percent of the total vitreous volume
3.Medullary vitreous
 Majority of the vitreous body is formed by the central medullary vitreous
 Similar to the cortical vitreous except it is a less fibrillar structure and cell
free

6. function
 Screen out UV and IR light
 Provide a clear media for optical transmission
 Protection of the media

7. composition
 The vitreous body is composed of three major structural components :
 Water
 Collagen- like fibers ,
 Hyaluronic acid a glycosaminoglycans ( GAGs)
 Collagens gives the vitreous its substance and the sodium hyaluronate
provides the viscoelasticity
 The human vitreous is typically gel
1.composed of randomly arranged collagen fibers and soluble hyaluronic acid
2. collagen : the protein of the vitreous is called vitrosin
3. determined to be collagen for several reason :

8.  has the amino acid hydroxyproline which is specific to collagen
 Has the same X-ray diffraction properties as collagen
 Normal ionic composition : the vitreous, except for collagen and sodium
hyaluronate , is very similar to the aqueous
 (a) oxygen : the oxygen in the vitreous comes from the arteries of the retina
 (b) water : the water in the vitreous is exchanged about every 30 min.
_ water movement of 85 mm3/min
 Sodium – enters anteriorly from the ciliary body and posterior chamber
- 90% of the sodium in the vitreous is exchanged in 24 hrs, mainly
flows to the aqueous

9.  Potassium
1. Enters by active transport through the ciliary epithelium into the posterior
chamber
2. Diffuses into the vitreous from lens and posterior chamber
3. Exists through the retina
 Chloride
1. There is a gradient of chloride from the vitreous to the aqueous
2. it is removed by retina and the posterior chamber

10.  Phosphate
1. Enters the vitreous via ciliary body
2. Low concentration in the vitreous because is used by the retina
3. If retina damaged , conc. of phosphate goes up in vitreous
 Glucose
1. Glucose diffuses into the vitreous from all the tissues
 Protein
1. The blood – vitreal barrier blocks the movement of most protein into the
vitreous