Transcript ACG - Dr. Kumar Saurabh

ANGLE-CLOSURE GLAUCOMA
RISK FACTORS AND PATHOGENESIS
SPEAKER: KUMAR SAURABH
HISTORICAL OVERVIEW
Glaucoma
Acute Glaucoma
Narrow Angle Glaucoma
A Greek word meaning ‘Clouded Vision’
First used by Lawrence to describe severe
ocular inflammation.
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 GLAUCOMA
Based On Pathogenic Mechanism
A. WITH PUPILLARY BLOCK
 Primary Angle-Closure Glaucoma
 Acute
 Sub acute
 Chronic
 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
 AGE
Common 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
 GENDER
Females have three times higher incidence than males
Reason: Females have shallower anterior chamber than males.
Continued:
 RACE
Most common in South-East Asians, Chinese and Eskimos.
Common in Caucasians.
Least common in Blacks.
 HEREDITY
Most cases of primary angle-closure glaucoma are sporadic.
No HLA association.
Narrow angle characteristics are inherited under polygenic gene influence.
 REFRACTIVE ERROR
Common 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.
 DRUGS
Sympathomimetics, anticholinergics and strong miotics.
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 BLOCK
Pupillary block occurs secondary to some pathological change in the eye.
 SWOLLEN LENS
(PHACOMORPHIC GLAUCOMA)
Swollen lens
Iris-lens apposition
Pupillary block
 MOBILE LENS SYNDROME
(ECTOPIA LENTIS AND MICROSPHEROPHAKIA)
Lens in anterior chamber
Pupillary block
 EXTREME MIOSIS (ANTICHOLINESTRASES)
Pupillary constriction
Ciliary contraction
Lens-iris apposition
Forward lens movement
Pupillary Block
 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 mm
Lens/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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