Anatomy of Anterior Chamber Angle and Physiology Of
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Transcript of Anatomy of Anterior Chamber Angle and Physiology Of
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Anatomy of anteriorchamber angle andphysiology of aqueousformation & secretionBy: Dr Anumeha
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ANATOMY OF ANTERIOR
CHAMBER ANGLE Angle forms the lateral boundary of the
ant chamber.
It consists specifically of :
Schwalbes line
Scleral spur
Trabecular meshwork and
Ciliary muscle bands
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A) Schwalbes line:
.Forms peripheral boundary of cornea.
.marks the end of normal corneal
endothelium..here the ant chamber angle
begins with the initial beams of the
trabecular meshwork.
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B) Trabecular meshworkis sieve like and consists of:
Uveoscleral meshwork: innermostExtends from root of iris to Schwalbe
lineHas cord like meshes which arerelatively large
corneoscleral meshwork: larger middle portionextends from schwalbe line to scleral
spurhere meshes are sheet like and small
endothelail meshwork: it is outer part called juxtracanalicularlinks corneoscleral part with theendothelium of inner wall of schlemmcanal
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C)scleral spur: forms the projection of collagen
fibers from inner sclera
Provides ant insertion of longitudinalciliary muscle fibers and is origin
of corneoscleral meshwork
D) Ciliary body band: represents ant aspect of ciliary
muscle into which iris root isinserted.
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Anatomy of ant chamber angle: a) uveal meshwork b)corneoscleralmeshworkc)schwalbe line d) schlemm canal e) collector channels f)
longitudinal muscles of ciliary body g) scleral spur
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Gonioscopic view of ant chamber angle
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PhysiologyAqueous humor regulation consists of
.Aqueous formation/secretion
.Aqueous outflow
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Aqueous humor formation / secretion
. It begins with the ultra filtration of plasma from the ciliaryprocess capillaries.
. The inner surface of ciliary body borders a part of postchamber.it has two parts:
Pars plicata and pars plana
Pars plicata: IT has ciliary processes which project into postchamber and is lined by pigment epitheliumwhich is cont with pig epithelium of retina and a non-pig epith which is cont with neuroretina
Each ciliary process has central arteriole, ending inthe capillary network.
Plicata is responsible for the formation of aqueous.
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The tight junction called as ZONA OCCLUDENS betwthe non pigmen epith cells forms the blood aqueous
barrier
The non pigmented epith actively secrets the aqueous.
Histologically fenestrated capillaries,a loose connectivetissue stroma and a metabolically double layeredepithelium forms the basis of aqueous humorformation.
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Ultrafiltration represents an important first step inaqueous humor production by which plasma
constituents gain entry into the ciliary processstroma,
The capillaries of the ciliary processes are unusually
permeable and the ultrafiltrate is rich in proteins
Following ultrafiltration, the next step in aqueousformation is active secretion of ions by the
nonpigmented layer of the ciliary epithelium.
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The tight junctions between the nonpigmented ciliaryepithelial cells ensure that the accumulation of ions inthe intercellular cleft creates a strong osmoticgradient, along which water will flow into theposterior chamber
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Na/K ATPase pump(present on the epith) plays imp rolein the aqu secrtn.the Na gets actively secreted inpost chamber..this causes passive flow of water inpost chamber
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Inhibition of ATPase enzymes causes decr in aqueousformation
The presence of tight junctns bet epithel is essentialfor the formation and maintain of osmotic gradient.
Oxy and glucose do not enter aqueous as they arerequired by lens and cornea
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Aqueous humor flow
Avg aqueous flow is approx 2.75 microLit /min
In morning it is 3.o microLit /min
At night it is 1.2 microlit /min
Aqueous flows from post chamber via pupil in to antchamber.
Two ways of aqueous flow:1) Conventional (canalicular,trabecular)
2) Unconventional (extracanalicular,uveoscleral)
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Conventional flow (canalicular,trabecular)
Accounts for 90% of flow
Flow is through trabeculum into Schlemm canal intoaqueous vein and then drains to episcleral veins
This is pressure sensitive route.inc in pressure willcause inc in the outflow
Out flow can be inc by miotics, trabeculotomy andlaser trabeculoplasty
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Unconventional way(uveoscleral)
Accounts for 10% of flow
Flow is through ciliary body to suprachoroidal spacedrained by venous circulation in sclera and cornea
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a) Conventional way
b) Unconventional way
c) Through iris(very very less flow occurs)
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Diagram showing both conventional and unconventional outflow
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Aqueous flow
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Special considerationBlood supply to the ant uvea
Ant uvea consists of iris and ciliary body along with its
processes
These receive blood from the anastomosis formed bet longant and post ciliary arteries.
Anastomosis is present in the ciliary muscles.
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Blood supply is through the three anastomoticcircles:
A) Episcleral circle: formed by branches of antciliary art
B) Intramuscular circle: formed by branches of longpost ciliary art and branches from perforating antiliary arte.
C) Major arteriolar circle: present at the root ofiris,formed by ant extention of intramascular circle.
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Branches from the maj arteriol circle supplyarterioles to the iris and to ciliary processes
On entering the processes these form the dilatedirregular capillaries..these capillaried are enestratedwhich forms the basis for the aqueous formation