8-Anterior chamber

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ANTERIOR CHAMBER AFFECTIONS

The anterior chamber is the space formed anteriorly by the come) and posteriori'y by the iris and is filled with aqueous humour. The filtration angle lies between the iris and cornea.

The anterior chamber is examined for its depth (either deep or shallow) and contents. Also the filtration angle is examined by gonioscopy.

I-SHALLOW ANTERIOR CHAMBER: -

Causes:

1-Anterior displacement of the lens forcing the iris forward and reducing the size of anterior chamber

2-Posterior synechia. When the edges of the iris are sealed to the lens in a complete circular ring, the aqueous humour cannot pass to the anterior chamber and causes pressure over the iris forward resulting in iris bombe.

3-Tumor of the iris

4-Corneal perforation and loss of aqueous humour.

II-DEEP ANTERIOR CHAMBER: -

1-Congenital microphakia (small lens)

2-Buphthalmia in chronic glaucoma

III-ABNORMAL CONTENTS OF THE ANTERIOR CHAMBER: -

Normally the anterior chamber contains aqueous humour. With bright focal beam of light, a faint relucence is seen along the path of light as a result of the light reflected from very minute particles suspended in the aqueous. In uveitis, large particles are present and reflect light in a fashion of searchlight beam at night.

1-Hypopyon: -

Definition:

Inflammatory exudates or pus in the anterior chamber

Causes:

1-Ulcerative keratitis              2-Anterior uveitis

Symptoms:

The inflammatory exudates settle to the lower part of the anterior chamber. In corneal ulceration, the hypopyon may have a roughly triangular shape with part of it adherent to the corneal ulcer.

Treatment:

Is directed first to treat the cause

1-Medical treatment by Alphachemotrypsine

2-Paracentesis and aspiration of the hypopyon by using sterile needle

3-Removal of the hypopyon through a stab puncture at the limbus by broken razor blade or cataract knife. The clotted exudates are removed by iris hook and the wound is sutured by simple interrupted stitches. The anterior chamber is reformed by antibiotic solution.

2-Hyphaema: -

Definition:

Hemorrhage or blood in the anterior chamber.

Causes:

1-Direct trauma by penetrating foreign body as thorn, stick or buckshotor indirect by severe blows to the eyeball or head

2-Iridocyclitis frequently produce hyphaema

3-Infectious disease as equine periodic ophthalmia

4-Chronic glaucoma especially when the eyeball increased in size (Megaloglobus). The hemorrhage may originate either from the ciliary body or from retinal detachment and is usually unclotted.

5-Primary and metastatic anterior uveal neoplasms as malignant lymphoma and haemangiosarcomas

6-Retinal vascular disease may produce hemorrhage and accompanied or not by retinal detachment.

7-Anterior chamber paracentesis. The iris is usually the source of hemorrhage.

Treatment:

1-Correction of the primary cause

2-Hemorrhage due to trauma usually clear up in 24 hours without treatment

3-Topical application -of 1-2% epinephrine solution for 24 hours only and then apply atropine to dilate the pupil until all hemorrhage has disappeared.

4-Injection of fibrlnolysin enzyme intracameral to remove blood clot

5-Surgical removal of the clot is rarely indicated. Small limbal incision can be performed and'the clot la hooked to an iris hook to bring it out.

3-Fibrin (plasmoid aqueous): -

Fibrin escape into the aqueous humour in cases of anterior uveitis and in such conditions resulting in reduction of intraocular pressure such as intraocular surgery, perforating wound, and paracentesis

Symptoms:

The fibrin clot may adhere to the cornea resulting in leucoma or to the lens and iris resulting in synechia and iris bombe. Also it may obliterate the filtration angle and cause glaucoma.

Treatment: Treat the cause      

Injection of fibrinolysin intracameral

4-Lipid aqueous:  -

Presence of lipids and lipoproteins in the aqueous humour is correlated with hyperlipaemia in dogs. The blood aqueous barrier appears to be destructed by iridiocyclitis and permit the entrance of lipid into the anterior chamber. The fat droplets in the aqueous give it a milky appearance. This can fill the lower part of the anterior chamber or the entire anterior chamber.

Treatment:

Low fat diet and thyroid therapy will clear up the aqueous within a week.

5-Lens: -

It may be luxated into the anterior chamber or ruptured and its material is mixed with the aqueous humour.

Treatment:

Removal of luxated lens.

6-Abnormal growth: -

Several types may be present such as:

1-Anterior uveal tumour (lymphosarcoma and melanomas)       2-granuloma. It is usually fibrin clot

3- Iris or ciliary body cyst

Treatment:

Surgical

7-Parasites:-

Migrating heart worm in dogs may gain access to the anterior chamber or flaria larvae in horses.

Treatment:

Parasites are removed surgically and the animal is treated by antiparasitic drugs

8-Foreign bodies: -

Thorns and birds shot (shotgun pellets). Such foreign bodies are removed surgically.