ANGLE-CLOSURE GLAUCOMA

RISK FACTORS AND PATHOGENESIS

SPEAKER: KUMAR SAURABH

HISTORICAL OVERVIEW

Glaucoma A Greek word meaning ‘Clouded Vision’

Acute Glaucoma First used by Lawrence to describe severe ocular inflammation.

Narrow Angle Glaucoma First described by Barkan based

on observation of opening of closed angle

by iridectomy.

CLASSIFICATION OF GLAUCOMA

Based On Pathogenic Mechanism

ANGLE-CLOSURE GLAUCOMA

OPEN-ANGLE GLAUCOMA

COMBINED-MECHANISM GLAUCOMA

DEVELOPMENTAL GLAUCOMA

DEFINITION

Angle-closure glaucoma

is the glaucoma

characterised by

reduced aqueous outflow and

elevated intraocular pressure

due to blockade of trabecular meshwork

by peripheral iris.

CLASSIFICATION OF ANGLE-CLOSURE GLAUCOMABased On Pathogenic Mechanism

A. WITH PUPILLARY BLOCK

Acute

Sub acute

Chronic

Primary Angle-Closure Glaucoma

Secondary Angle-Closure Glaucoma

Swollen lens

Mobile lens syndrome

Miotic induced Continued:

B. WITHOUT PUPILLARY BLOCK

Primary Angle-Closure Glaucoma

Plateau iris configuration

Plateau iris syndrome

Secondary Angle-Closure Glaucoma

Due to anterior pulling mechanism

Due to posterior pushing mechanism

Continued:

Anterior Pulling mechanism

Neovascular Glaucoma

Iridocorneal endothelial syndrome

Posterior Polymorphous Dystrophy

Aniridia

Posterior pushing mechanism

Aqueous misdirection syndrome

Nanophthalmos

Cysts of iris and intraocular tumors

Intravitreal air injection

Suprachoroidal Hemorrhage

Scleral Buckling

Retrolental Fibroplasia

RISK FCTORS FOR DEVELOPMENT

OF ANGLE-CLOSURE GLAUCOMA

AGECommon in old age i.e. 6th-7th decade of life.

Reason: Continuous growth of lens Anterior displacement of lens Increased elasticity of iris Increased miosis

GENDERFemales have three times higher incidence than males

Reason: Females have shallower anterior chamber than males.

Continued:

RACEMost common in South-East Asians, Chinese and Eskimos.

Common in Caucasians.

Least common in Blacks.

HEREDITYMost cases of primary angle-closure glaucoma are sporadic.

No HLA association.

Narrow angle characteristics are inherited under polygenic gene influence.

REFRACTIVE ERRORCommon in hypermetropes; rare in myopes.

Reason: Smaller eye and shallow anterior chamber in hypermetropes.

Continued:

SEASON

More common in winter months due to low illumination.

SYSTEMIC DISORDERS

Inverse correlation between abnormal glucose tolerance and

anterior chamber depth.

EMOTIONAL UPSET

Due to excessive sympathetic activity.

Sympathomimetics, anticholinergics and strong miotics.

DRUGS

PATHOGENESIS

PRIMARY ANGLE-CLOSURE GLAUCOMA WITH PUPILLARY BLOCK

Two factors are responsible:

Lens-iris apposition

Anatomic considerations

LENS-IRIS APPOSITION

Contact of posterior iris surface with anterior lens surface

Resistance to passage of aqueous from posterior to anterior chamber

Relative pupillary block

Greater pressure difference between posterior and anterior chambers

Forward bowing of peripheral iris

Blockade of trabecular meshwork

Reduced aqueous outflow

Rise in intraocular pressure

Angle-Closure Glaucoma

ANATOMIC CONSIDERATIONS

Shallow anterior chamber (<2.5mm)

Decreased anterior chamber volume

Short axial length of globe

Small corneal diameter

Decreased corneal height

Increased posterior corneal curvature

Increased lens thickness

Anterior position of lens.

More anterior insertion of iris on ciliary body.

Increased curvature of anterior lens surface.

ROLE OF IRIS MUSCULATURE

Forces Exerted By Iris Muscles: Parallel to the plane of iris Posteriorly

SPHINCTER MUSCLE

Posterior vector is: Minimum in miosis. Increases with dilatation. Maximum in mid-dilated(3-6mm)state.

Crowding of angle by peripheral iris: Maximum in mid-dilated state.

DILATOR MUSCLE

Posterior vector of dilator muscle is more pronounced in a predisposed eye, i.e. an eye with shallow anterior chamber.

During active dilation dilator muscle moves faster than the adjacent stroma, there by pulling the sphincter muscle closer to the lens and increasing the posterior vector of the latter.

SECONDARY ANGLE CLOSURE GLAUCOMA WITH PUPILLARY BLOCKPupillary block occurs secondary to some pathological change in the eye.

(PHACOMORPHIC GLAUCOMA)

Swollen lens Iris-lens apposition Pupillary block

MOBILE LENS SYNDROME

Lens in anterior chamber Pupillary block

EXTREME MIOSIS (ANTICHOLINESTRASES)

Pupillary constriction Lens-iris appositionCiliary contraction Forward lens movement

Pupillary Block

(ECTOPIA LENTIS AND MICROSPHEROPHAKIA)

SWOLLEN LENS

APHAKIA

Adhesion of iris to anterior vitreous face Pupillary block

PSEUDOPHAKIA (ACIOL usually)

Adhesion of iris to pseudophakos Pupillary block

Secondary angle closure glaucoma with pupillary block due to dislocated PCIOL.

Secondary angle closure glaucoma with pupillary block due to silicon oil.

PRIMARY ANGLE CLOSURE GLAUCOMA WITHOUT PUPILLARY BLOCK

There is little or no pupillary block, still peripheral iris occludes the trabecular meshwork.

PLATEAU IRIS CONFIGURATION Shaffer & Chandler

Central anterior chamber depth : Normal

Iris : Flat from pupillary margin to mid-periphery (plateau)Sharp turn posteriorly at mid-periphery and insertion at ciliary body creating a narrow angle recess.

Glaucoma is cured by iridectomy.

Associations : Anteriorly displaced ciliary body pressing on iris periphery. Ciliary body cysts.

PLATEAU IRIS SYNDROME

Features are similar to Plateau Iris Configuration except that it is not cured by iridectomy.

SECONDARY ANGLE CLOSURE GLAUCOMA WITHOUT PUPILLARY BLOCK

ANTERIOR PULLING MECHANISM

NEOVASCULAR GLAUCOMA

Formation of ectropian uveae and latter peripheral anterior synechiae due to pull of the fibrovascular membrane over iris.

IRIDOCORNEAL ENDOTHELIAL SYNDROME

Pull by the tonofilaments in the “epithelialised” endothelium and Descemet’s membrane of cornea over iris.

POSTERIOR POLYMORPHOUS DYSTROPHY

Dysplastic corneal endothelium produces basement membrane like material

which covers the angle.

POSTERIOR PUSHING MECHANISM

AQUEOUS MISDIRECTION SYNDROME

Surgery/Insult to the eye Ciliary body swelling and forward rotation Contact with zonules/lens Aqueous secretion in vitreous pockets Anterior hyaloid and lens move forward Anterior chamber collapse.

NANOPHTHALMOS

Eye is normal in shape but smaller in size.Antero-posterior diameter < 20 mm.Corneal diameter < 11 mmLens/Eye volume ratio :10-25% (Normal 3-4%)Angle closure is precipitated by choroidal effusion leading to forward rotation of ciliary body and loosening of zonules.

CENTRAL RETINAL VEIN OCCLUSION

Decreased venous drainage of uveae Swelling and forward rotation of ciliary body Loosening of zonules Forward lens movement.

Continued:

SUPRACHOROIDAL HEMORRHAGE

POSTERIOR SCLERITIS

SCLERAL BUCKLING

PANRETINAL PHOTOCOAGULATION

RETINOPATHY OF PREMATURITY.

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