3. INTRODUCTION
Aqueous is a thin, watery fluid that fills the
space between the cornea and the iris (anterior
chamber).
Aqueous humour dynamics plays an important
role in development of pathophysiological
mechanism of Glaucoma.
4.
5. FUNCTIONS
Maintains the intraocular pressure.
Provides nutrition (e.g. amino acids and
glucose).
Carries away waste products.
Transports ascorbate in the anterior segment to
act as an anti-oxidant agent.
Presence of immunoglobulin indicates a role in
6. PHYSIOLOGICAL
PROPERTIES
Volume 0.31ml (0.25 ml in anterior chamber and
0.06 ml in posterior chamber)
Refractive index 1.333
PH 7.2
Hyper osmotic
Rate of formation 2.0 to 3.0 μl/min
9. DYNAMICS
Anatomy of the structures involving aqueous
humour formation and drainage
Aqueous humour formation
Aqueous humour drainage
10. ANATOMY
Primary ocular structures involved are:
Ciliary body
Posterior chamber
Anterior chamber
Angle of anterior chamber
Aqueous outflow system
11.
12. CILIARY BODY
Site of aqueous production
Triangular in shape
Outer side- lies against the sclera with a supra
choroidal space in between
Inner side of ciliary body has two parts
A) Anteriorly- pars plicata (finger like ciliary process)
B) Posteriorly- pars plana
13.
14. Ciliary muscle- non striated muscle - three parts
1. Longitudinal or meridional fibers- helps in
aqueous outflow and accomodation
2. Circular muscles- helps in accomodation
3. Radial or oblique fibers- helps in accomodation
CLINICAL CORRELATION
Pilocarpine, acts at parasympathetic muscarinic receptor site to cause ciliary
muscle spasm and pupillary miosis.
Contraction of the ciliary muscle produces traction on the trabecular meshwork,
facilitating aqueous humour drainage and lowering IOP.
15.
16. CILIARY PROCESSES
70-80 whitish finger like projections
Composed of double layer epithelium over a
core of stroma and a rich supply of fenestrated
capillaries.
Apical surface of inner non-pigmented
epithelium (NPE) and outer pigmented
epithelium (PE) are joined by tight junctions
which contributes to Blood- Aqueous barrier.
17.
18.
19. Vascular Supply of Ciliary Body
The major arterial circle, which is formed by
anastomosis between the long posterior ciliary
artery and anterior ciliary arteries.
CLINICAL CORRELATION
Brimonidine, an α- adrenergic agonist commonly used for glaucoma treatment,
reduces aqueous formation by causing vasoconstriction of ciliary arterial supply.
20.
21. POSTERIOR CHAMBER
Triangular space
0.06 ml of aqueous humour
Boundaries:
Anterior : Posterior surface of iris and part of
ciliary body
Posterior : Crystalline lens and zonules
Lateral : Ciliary body
23. CILIARY BAND
Most posterior landmark in angle recess which
is viewed as a dark band on gonioscopy
Represents the anterior face of ciliary body
including insertion of ciliary muscle into scleral
spur
24. SCLERAL SPUR
Pale, translucent narrow strip of scleral tissue
Marks the posterior boundary of scleral sulcus
25. TRABECULAR MESHWORK
Broad band of tissue extending from Scleral
Spur to Schwalbe’s Line
No pigmentation at birth but develops pigment
with increasing age.
CLINICAL CORRELATION
Some pathological conditions can cause increased pigmentation like:
• Pseudo exfoliation syndrome
• Pigment dispersion syndrome
26. SCHWALBE’S LINE
Anterior limit of the drainage angle
Seen as fine scalloped border at the
termination of Descemet’s Membrane of
cornea
CLINICAL CORRELATION
In 15-20% of normal subjects, it may be hypertrophied and project as thin,
glistening ridge in Anterior Chamber.This condition is known as Posterior
Embryotoxon.
28. ANTERIOR CHAMBER
2.5-3 mm deep in centre
Contains 0.25ml of aqueous humour
Boundaries:
Anterior- Posterior surface of cornea,
Posterior- Anterior surface of ciliary body and
iris
Communicates with posterior chamber through
29. AQUEOUS FORMATION
Ciliary processes are the main site of aqueous
humour production.
Mainly by thee mechanisms:
1. Ultrafiltration-20%
2. Active secretion-70%
3. Diffusion-10%
30. ULTRAFILTRATION
Process by which fluids and its solutes crosses
semipermeable membrane under pressure
gradient.
Favored by hydrostatic pressure difference
between the capillary pressure and the
interstitial fluid pressure.
Resisted by the pressure difference between
oncotic pressure of plasma and aqueous
31. Ultra filtration helps to move fluid out of the
capillaries into the stroma but alone is
insufficient to account for volume of fluid moved
into the posterior chamber.
32. ACTIVE TRANSPORT
Energy dependent process.
Selective movement of a substance against its
electrochemical gradient across a cell-
membrane.
Depends on ion/s being actively secreted into
inter-cellular clefts of non-pigmented epithelial
cells beyond tight junctions.
33. Main ions to be actively transported across the
non-pigmented epithelium include Sodium,
Chloride, Bicarbonate
Active transport of Na+ is the key feature of
aqueous production
34. DIFFUSION
Passive movement of ions across a membrane
along its concentration gradient.
Lipid soluble substances are transported by
diffusion through the lipid portions of the cell
membrane of the ciliary processes.
35. STEPS OF AQUEOUS
FORMATION
Formation of stromal pool
Active transport of stromal filtrates
Passive transport across non-pigmented ciliary
epithelium
37. TRABECULAR MESHWORK
Sieve like structure through which aqueous
humor leaves the eye.
It converts the scleral sulcus into a circular
channel, called the Schlemm canal.
Allows the bulk flow aqueous out of the
anterior chamber but prevents blood reflux
into anterior chamber.
38. Hence, forms the crucial part of normal blood-
aqueous barrier
Fibronectin, elastin, laminin, collagen (types I,
III, IV, V and VI), smooth muscle myosin
containing cell are the integral components of
trabecular meshwork.
39. It is divided into three
portions:
1. Uveal Meshwork
2. Corneoscleral
Meshwork
3. Juxtacanalicular
Meshwork
40. UVEAL MESHWORK
Innermost part, extended from iris root and
ciliary body to Schlemm’s Canal
The trabeculae of uveal meshwork are cord like
and 2 to 3 layers thick containing irregular
openings varying in size from 25μ to 75μ.
41. CORNEO-SCLERAL
MESHWORK
Larger middle portion extending from scleral
spur to lateral wall of scleral sulcus
Consists of flat sheets of trabeculae with
elliptical openings ranging from 5μ to 50μ
42. JUXTA-CANALICULAR
MESHWORK
Outermost portion of trabecular meshwork
It mainly offers resistance to normal aqueous
outflow
This narrow part of trabeculum connects
corneoscleral meshwork with Schlemm’s Canal.
43. SCHLEMM’S CANAL
Endothelial lined oval channel present
circumferentially in the scleral sulcus
Cells of inner wall are irregular, spindle
shaped and contains giant vacuoles
Cells of outer wall are smooth and flat
containing numerous opening of collector
channels.
44. COLLECTOR CHANNELS
Also called
Intrascleral Aqueous
Vessels
25 to 35 in number
Leave Schlemm’s
Canal at oblique
angles to terminate
ultimately into
46. AQUEOUS HUMOR
OUTFLOW
Conventional or trabecular outflow
(90% of the aqueous outflow)
Unconventional or uveoscleral outflow
(10% of the aqueous outflow)
47. CONVENTIONAL OR
TRABECULAR OUTFLOW
The aqueous humor leaves the eye at the
anterior chamber angle through trabecular
meshwork, the Schlemm’s canal, intrascleral
channels, and episcleral and conjunctival veins.
48. UNCONVENTIONAL OR
UVEOSCLERAL OUTFLOW
The aqueous humor exits through the root of
iris, between the ciliary muscle bundles, then
through the suprachoroidal – scleral tissues.
CLINICAL CORRELATION
Prostaglandins used to reduce IOP in various conditions including glaucoma
reduce IOP by
increasing the aqueous drainage via this pathway.
49.
50. Ciliary Process
Posterior Chamber
Anterior Chamber
Ciliary Body
Suprachoroidal
Space
Venous circulation
of ciliary body,
sclera and orbit
Trabecular
Meshwork
Schlemm’s Canal
Collector Channels
Episcleral Veins
Uveoscleral
Outflow(10%)
Trabecular
Outflow(90%)
51. Different Mechanisms of Outflow
Obstruction
POAG - loss of trabecular endothelial cells, collapse
of schlemms canal, obstruction of collector channels.
Infantile glaucoma – outflow structures not developed
properly (Trabeculodysgenesis).
Angle closure glaucoma – peripheral iris pushed
against meshwork.
Secondary open angle – obstruction by fibrovascular
tissues, RBCs, WBCs, tumor cells, pigment & lens
particles.
52. PHARMACOLOGY
Pilocarpine:
Miotic induced
contraction of sphincter
pupillae -> pulls the
peripheral iris away from
the trabeculum -> opens
the angle.
Contraction of the cilairy
muscle-> traction on
trabecular meshwork ->
drains the aqueous.
Editor's Notes
Keeps eyeball distended….Cornea and lens……….blood macrophages, remnats of lens matter, products of infl……
RI slightly lower than cornea 1.37…..PH acidic
Plasma proteins 6-7 gm/100ml………….Ascorb, pyru, lact more in AH than plasma……Urea, glu less in AH
Forward continuation of choroid at ora serrata…..posterior smooth part
Parasympathetic fibres from ciliary ganglion….Ciliary muscle contracts->zonules relaxes->lens spherical->inc refractive power to accommodate closer view….longitudinal is attached to scleral spur, helps in outflow
Pigmented is cont of retinal pigmented layer and cont as ant pigmented layer of iris
Nonpigm is cont of sensory retina and cont as post pigmented layer of iris
Ophthalmic—nasociliary---
Post to ant……ant part of ciliary body, width depends upon insertion of root of iris…posterior portion of scleral sulcus....trab meshwork no pigment at biirth…..fine ridge, schwalbes line is formed by prominent end of descmet mebrane of cornea
Shaffers system of grading in gonioscopic view
Shallow in hypermetropia
AH is primarily derived from plasma within the capillary network of the ciliary process.