Primary Angle Closure Glaucoma

Primary Angle Closure Glaucoma

Introduction • ACG as a cause of world

blindness is probably 3 times more likely than OAG especially in Asia.

Open angle Closed angle

What is Primary closure glaucoma?

• PRIMARY ANGLE CLOSURE GLAUCOMA(PACG) includes a spectrum of conditions in which the peripheral iris moves forwards to block the openings of trabecular meshwork at the angle causing a rise of intraocular pressure.

• The condition may manifest as an ophthalmic emergency.

• Unlike POAG the diagnosis largely depends on examination of anterior segment and careful gonioscopy.

• Management requires an understanding of underlying pathophysiological mechanisms.

Normal angle Closed angle

What are the Risk Factors?

a. Age: age of presentation is about 60yrs, prevalence increases thereafter.

b. Race: more common in south-east asians, chinese, eskimos but uncommon in blacks.

c. Sex: significant predominance of females by a ratio of 4:1.

d. Refractive Error: More common in hypermetropes because of shallower anterior chamber.

e. Family History: generally believed to be inherited.

f. Systemic disorders: type II Diabetes is associated with decreased anterior chamber depth.

g. Seasonal incidence: more common in

the winter months.

Anatomical predisposing factors

1. Relatively anterior location of iris lens diaphragm secondary to short axial length.

2. Shallow anterior chamber.3. Narrow enterance to chamber

angle.

Primary angle closure

Precipitating factorsI . Factors that produce mydriasis : a. Dim illumination b. Emotional stress c. Drugs (Mydriatics – anticholinergics ).II . Factors that produce miosis : strong

cholinesterase inhibitor miotics.III . Sulpha based compounds that produce

transient myopia due to lens swelling and forward movement of lens iris diaphragm.

a. RELATIVE PUPIL BLOCK

b. IRIS BOMBE

c.IRIDOCORNEAL CONTACT

MECHANISM

Types of Angle Closure Glaucoma

(Based on symptoms and Clinical Findings)

1. Primary angle closure glaucoma suspect

2. Sub-acute angle closure glaucoma (also called intermittent/ prodromal or subclinical glaucoma).

3. Acute angle closure glaucoma4. Chronic Angle Closure Glaucoma5. Combined Mechanism Glaucoma

Primary angle closure glaucoma suspect

1. Symptoms are absent.2. Slit lamp Biomicroscopy: a.Shallow anterior chamber and iris-lensDiaphragm is convex.b. Close proximity of iris to the cornea.

3. Gonioscopy: shows an an Occludable Angle in which the pigmented trabecular

meshwork is not visible without indenta- tion in atleast 3 out of 4 quadrants.The drainage angle insuch eyes is generallyGrade II or less i.e. less than 20 degrees.

Clinical course

IOP may remain Chronic angle

normal closure (may

Acute or develop without

subacute angle passing thro-

closure ugh acute or

subacute stage)

Treatment If ONE eye has had acute or sub acute angle closure

If BOTH eyes have occludable angles

The fellow eye should undergo prophylactic peripheral laser iridotomy.

Laser treatment may be considered.

Intermittent angle closure• Shallow anterior chamber with an occludable angle with a narrow angle

recess in which physiological mydriasis precipitates a pupillary block resulting in sharp rise in IOP for a short

period of time followed by spontaneous resolution.

Diagnosis • Based on characteristic history of

unilateral headache, browache, blurring of vision on same side & unbroken colored halos around lights during episode (d/t corneal edema).

• Between these attacks, eye is free of symptoms & only shows signs of a narrow angle recess, clumping of pigment in the angle or occasional PAS.

Treatment Prophylactic peripheral laser iridotomy

L P I

Acute angle closure• Caused by sudden occlusion of the entire angle

with a resultant rise of IOP to extremely high levels(50-60mmHg).

• C/O severe unilateral headache, nausea & diminision of vision in a RED EYE.

• O/E ciliary & conjuctivalcongestion, corneal edema,a shallow anterior chamber,& iris bombe with a vertically oval, mid-dilated pupil are present.

• After resolution of corneal edema, a gonioscopically closed angle can

be seen,i.e.extensiveIridocornealsynechiae.

• The optic disc may be hyperaemic or normal.

• Visual fields shows non-specific constriction. It may be constriction of upper field or nerve fibre bundle defect.

Treatment 1. Careful history of symptoms relating to

intermittent angle closure attacks in the other eye, use of prescription or non-prescription drugs which may precipitate attacks, and type of activity preceding the attack.

2. Examination of the affect-ed eye and other eye withattention to central andperipheral anterior chamberdepth as well as the shape of the peri- pheral iris.

3.Administration of oral isosorbide and one or more topical aqueous suppressants. Intravenous acetazolamide can be given according to the surgeon’s preference.

4.The pt lies supine to permit the lens to fall posteriorly with vitreous dehydration.

5. The eye is reassesed after 1 hour. IOP is usually decreased, but the angle usually remains appositionally closed. One drop of 2% or 4% pilocarpine is given and the pt reexamined 30 min later.

If IOP is reduced and angle open

Low dose pilocarpine + aq. Suppressants

+ steroids.

Eye quiet

Do LPI

If IOP unchanged or ­ and angle remains

closed Suspect lens related angle closure

With hold pilocarpine

Do ALPI

If eye quiets – Do LPI

Chronic Angle Closure Glaucoma

• Asymptomatic, diagnosis is reached if IOP is chronically raised in eyes having synechial closure over at least 180 degrees. Changes in optic n. head & visual field may or may not be present.

MECHANISM :• Peripheral Anterior Synechiae (PAS) may

develop with prolonged or recurrent acute or subacute attack leading to chronic angle closure glaucoma.

• PAS in acute angle closure are broad based and are seen in superior quadrant and correlate with duration of acute attack.

• Synechial closure is referred to as shortening of the angle – creeping angle closure. This condition can be prevented by timely peripheral iridotomy.

Treatment • Laser iridotomy to eliminate pupil

block.• Medical therapy to treat any residual

elevation of IOP.• If this fails, trabeculectomy.

Combined MechanismGlaucomas

• Combined mechanism glaucomas refers to condition in which both, open angle and angle closure components are present.

• After successful treatment of angle closure glaucoma with iridotomy , eliminating all appositional closure the IOP still remains elevated. PAS may or may not be present.

• An eye with open angle glaucoma may develop angle closure due to natural development of pupillary block or result from miotic therapy.

PProvocative tests: ROVO1. Mydriatic Provocative test: topical Tropicamide

1% rise of IOT-8 mmHg/more is considered positive test.

2. Dark Room Provocative test: Exposure to dark for 60 – 90 min – rise of 8 mm Hg/more is considered positive test.

3. Prone Provocative test : Prone position for 60 min , rise of 8 mmHg/more is considered positive test.

4. Pilocarpine/Phenylephrine ProvocativeTest: 2% Pilocarpine and 10% Phenylephrine are instilled simultaneously every minute for 3 applications to achieve mid dilated pupil – rise of 8 mmHg/more is considered positive test.If negative repeat the test . If negative after 90 min,test is terminated by 0.5% Thymoxamine(alpha adrenergic agonist).

Management Goals

• Identification of patients at risk of developing primary angle closure (PAC) glaucoma or to identify patients with PAC

• To manage an acute attack• To prevent permanent damage to angle of

anterior chamber• To ensure that patient leads a symptom

free life• To observe for chronic IOP elevation,

progression of synechial angle closure / optic nerve damage and treat as indicated

MEDICAL THERAPY

• Approachese. To reduce IOPf. To relieve the angle closure

a. Reduction of IOP

• • ORAL THERAPY1. Acetazolamide2. Glycerol3. Isosorbid• • INTRAVENOUS THERAPY1. Mannitol2. Acetazolamide• TOPICAL THERAPY1. Pilocarpine2. Beta-adrenergic blockers

3. Alpha 2 Adrenergic Agonist4. Topical carbonic anhydrase inhibitor5. Topical miotic

b. Relief of Angle Closure• 1. Pilocarpine 1 or 2 %• 2. Topical thymoxamine 0.5%

(Eserine and Echothiopate Iodide are not indicated)

• 3. LASER PI• 4. If not possible then surgical /

incisional iridectomy• 5. Lensectomy

b. RELIEF OF ANGLE CLOSURE :

Filtration procedures

POST-TRAB BLEB

Plateau Iris

Plateau iris configuration

Plateau iris configuration is characterized by a near-normal-depth central anterior chamber,a flat iris profile, and crowding of the anterior chamber angle by the iris base. The IOP may be normal or elevated. The condition appears to be related to a forward displacement of the ciliary processes that causes anterior displacement of the peripheral iris and angle closure. Such closure occurs without a significant pupillary block component.

Plateau iris syndrome

Plateau iris syndrome is defined as having a plateau iris configuration with a closed anterior chamber angle and usually with elevated IOP, which persists despite the elimination of any pupillary block component by a patent iridotomy. Intraocular pressure elevation that was present before iridotomy may persist; the IOP typically increases after pupil dilation, which causes greater occlusion of the angle by the peripheral iris.

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