Vitreous (Attachments, age changes, vitreous hemorrhage, Vitreous Detachment)Maryam Fida
Vitreous
Vitreous is an inert, avascular, transparent, jelly like structure.
Serve as one of refractive media of the eye and has optical functions.
It gives structural integrity to eye and provide nutrients to the lens, ciliary body and retina.
Constitute 80% volume of the eye.
Contain collagen fibrils, mucopoly-saccharides and hyaluronic acid.
It’s a hydrophilic gel which become ‘’fluid’’ when protein coagulates.
Reasons for coagulation of proteins could be,
• Advancing senile age
• Degenerations, e.g. as in high myopia
• Chemical and mechanical trauma
Internal limiting membrane on inner surface of retina separate it from vitreous. There is potential space ‘subhyaloid space’ between two.
Figure 1 structures of vitreous
Vitreous attachments
1. Anteriorly to the lens and ciliary epithelium in front of ora serrata. Part of vitreous about 4mm across ora serrata is called as ‘base of vitreous’. Here, attachment is strongest.
2. Posteriorly to the edge of optic disc and macula lutea (foveal region) forming ring shaped structure around them.
Figure 2 vitreous attachments
Age changes in Vitreous
Vitreous undergo certain physical and biochemical changes with aging.
1. At birth_ the Cloquet’s canal runs straight from lens to optic disc. It contains primary vitreous.
2. In young persons_ vitreous gel is homogenous but its fibers become coarse with process of advancing age.
3. In old age and high myopes_ secondary vitreous liquified (syneresis) and shrinks, producing a vitreous detachment, vitreous and retinal hemorrhage and retinal break.
Figure 3 Vitreous at birth Figure 4 Vitreous in young adults.
Figure 5 vitreous detachment in old age
Vitreous Hemorrhage
Vitreous hemorrhage is the extravasation, or leakage, of blood into the areas in and around the vitreous humor of the eye.
TYPES
There are two types of vitreous hemorrhage.
1. Peripheral or subhyaloid hemorrhage _ occurs between retina and vitreous.
Blood remains fluid, red in color
Blood moves with gravity forming boat-shaped figure in macular area.
Figure 3 subhyaloid hemorrhage
2. Intravitreal hemorrhage_ the hemorrhage may get absorbed or degenerate to form a white fibrous tissue mass.
Etiology
Common causes of vitreous hemorrhage are;
i. Trauma_ by contusion or penetrating injury
ii. Vitreous retraction_ vitreous fibrous bands or membrane retraction
iii. Eale’s disease_ due to retinal vasculitis and periphlebitis
iv. Blood dyscrasias_ leukemia, sickle cell anemia, purpura.
v. Diabetes mellitus_ common in diabetic proliferative retinopathy
vi. Central retinal vein thrombosis
vii. Malignant hypertension_ often results in large intravitreal hemorrhage.
Symptoms
I. Black spots or clouds maybe seen in front of eye.
II. Impaired vision maybe up to perception of light.
Signs
1. Fundus examination
a) Faint or no red reflex seen
b) Grey opacities maybe present in vitreous
Figure 4 (A) Fundus exami
Vitreous (Attachments, age changes, vitreous hemorrhage, Vitreous Detachment)Maryam Fida
Vitreous
Vitreous is an inert, avascular, transparent, jelly like structure.
Serve as one of refractive media of the eye and has optical functions.
It gives structural integrity to eye and provide nutrients to the lens, ciliary body and retina.
Constitute 80% volume of the eye.
Contain collagen fibrils, mucopoly-saccharides and hyaluronic acid.
It’s a hydrophilic gel which become ‘’fluid’’ when protein coagulates.
Reasons for coagulation of proteins could be,
• Advancing senile age
• Degenerations, e.g. as in high myopia
• Chemical and mechanical trauma
Internal limiting membrane on inner surface of retina separate it from vitreous. There is potential space ‘subhyaloid space’ between two.
Figure 1 structures of vitreous
Vitreous attachments
1. Anteriorly to the lens and ciliary epithelium in front of ora serrata. Part of vitreous about 4mm across ora serrata is called as ‘base of vitreous’. Here, attachment is strongest.
2. Posteriorly to the edge of optic disc and macula lutea (foveal region) forming ring shaped structure around them.
Figure 2 vitreous attachments
Age changes in Vitreous
Vitreous undergo certain physical and biochemical changes with aging.
1. At birth_ the Cloquet’s canal runs straight from lens to optic disc. It contains primary vitreous.
2. In young persons_ vitreous gel is homogenous but its fibers become coarse with process of advancing age.
3. In old age and high myopes_ secondary vitreous liquified (syneresis) and shrinks, producing a vitreous detachment, vitreous and retinal hemorrhage and retinal break.
Figure 3 Vitreous at birth Figure 4 Vitreous in young adults.
Figure 5 vitreous detachment in old age
Vitreous Hemorrhage
Vitreous hemorrhage is the extravasation, or leakage, of blood into the areas in and around the vitreous humor of the eye.
TYPES
There are two types of vitreous hemorrhage.
1. Peripheral or subhyaloid hemorrhage _ occurs between retina and vitreous.
Blood remains fluid, red in color
Blood moves with gravity forming boat-shaped figure in macular area.
Figure 3 subhyaloid hemorrhage
2. Intravitreal hemorrhage_ the hemorrhage may get absorbed or degenerate to form a white fibrous tissue mass.
Etiology
Common causes of vitreous hemorrhage are;
i. Trauma_ by contusion or penetrating injury
ii. Vitreous retraction_ vitreous fibrous bands or membrane retraction
iii. Eale’s disease_ due to retinal vasculitis and periphlebitis
iv. Blood dyscrasias_ leukemia, sickle cell anemia, purpura.
v. Diabetes mellitus_ common in diabetic proliferative retinopathy
vi. Central retinal vein thrombosis
vii. Malignant hypertension_ often results in large intravitreal hemorrhage.
Symptoms
I. Black spots or clouds maybe seen in front of eye.
II. Impaired vision maybe up to perception of light.
Signs
1. Fundus examination
a) Faint or no red reflex seen
b) Grey opacities maybe present in vitreous
Figure 4 (A) Fundus exami
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4. Most of this humor consists of water, as well as a lower
amount of collagen, salt, and sugar.
Vitreous humor is the transparent, jelly like visual media
Occupies the posterior 4/5 of eyeball
Lies between lens and retina
Volume – 4ml
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This humor is a stagnant (immobile) fluid that is not
served by any blood vessels and is not actively
regenerated or replenished. (This is in contrast to the
aqueous humor, which fills the anterior chamber in
front of the lens.)
If a substance enters the vitreous humor, it will remain
suspended in the gel until it can be surgically removed.
These substances, which can include blood or clumps of
cells, are collectively referred to as floaters. If left alone,
floaters can affect a person's field of vision.
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It also contains hyaluronic acid and possesses a network of
fine collagen fibrils that form a scaffolding, which give it its
jelly-like properties.
Contains hyaluronic acid, aminoacids, salts, ascorbic acid.
Hyalocytes are basically mononuclear phagocytes or
macrophages.
7. Parts of vitreous humor
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Cortical vitreous
The outer part of vitreous close to the retina posteriorly
and the lens and ciliary body anteriorly
Arrangement of collagen fibers is denser
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These fibrils condense to form a false anatomical
membrane
anterior hyaloid membrane
in front of ora serrata
firmly attached to lens in young people and loosely attached in
elderly
posterior hyaloid membrane
behind ora serrata
loosely attached to internal limiting membrane of retina at all
ages
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Body of vitreous (nucleus)
The inner zone of vitreous.
True biological gel
Less dense
Liquefactions first start here
Cloquet’s canal / hyaloid canal passes through the
vitreous from the optic disc to posterior pole of lens
11. Attachments of vitreous
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Vitreous base-strongest
Posterior lens capsule with
the help of hyaloideocapsular
ligament of Weiger
Margins of the optic disc
At the macula
Along the retinal vessels –
Most variable and weakest
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Vitreous base
Vitreous base forms a band of
4 to 6 mm width (1 to 2 mm
anterior to the ora serrata
and 1 to 3 mm posterior to it)
which lies in the posterior
aspect of the parsplana and
adjacent anterior aspect of
the ora serrata.
13. Functions of vitreous
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Support function for the retina and filling up function of the
vitreous body cavity
Diffusion barrier between the anterior and the posterior
segments of the eye
Metabolic buffer function.
Shock absorbing .
Establishment of an unhindered path of light
