Vitreous humour 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

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