anatomy of anterior chamber angle and physiology of

7/29/2019 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

anatomy of anterior chamber angle and physiology of

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