Dr Md Ferdous Islam

Dept of Ophthalmolgy CMH,Dhaka

PRIMARY ANGLE CLOSURE GLAUCOMA

Angle Closure

Occlusion of the Trabecular Meshwork by the peripheral iris(iridotrabecular contact-ITC) obstructing the aqueous outflow

Stages In Natural History1 Primary angle-closure suspect (PACS) • Gonioscopy shows posterior meshwork ITC in

three or more quadrants but no PAS • Normal IOP, optic disc and visual field

2 Primary angle-closure (PAC) • Gonioscopy shows three or more quadrants of ITC

with raised IOP and/or PAS, or excessive pigment smudging on the TM • Normal optic disc and field

3 Primary angle-closure glaucoma (PACG) • Gonioscopy shows ITC in three or more quadrants

• Optic neuropathy

Risk Factors

• Positive family history for angle closure• Age : relative pupillary block 60 yrs or over. Younger

for non pupillary block• Women• History of Angle closure symptoms• Hypermetropia• Axial length• Racial group Indian Asians & Far Eastern

MechanismRelative Pupillary Block • Failure of aqueous flow through the mid dilated

pupil leads to a pressure differential between the anterior and posterior chambers, with resultant anterior bowing of the lax iris [Iris bombe] blocks trabecular meshwork and iridolenticular contact

Non-pupillary block • Specific anatomical factors include plateau iris

(anteriorly positioned ciliary processes), and a thicker or more anteriorly-positioned iris

• Plateau iris configuration is characterized by a flat central iris plane in association with normal central anterior chamber depth. The angle recess is very narrow, with a sharp iris angulation over anteriorly positioned and/or orientated ciliary processes

• Plateau iris syndrome describes the occurrence of angle-closure despite a patent iridotomy in a patient with morphological plateau iris

• Lens induced angle closure

• Retrolenticular

• Combined mechanism

• Reduced aqueous outflow

Shaffer grading

Ocular Manifestations• Symptoms Decreased vision Halos around lights Frontal headache Ocular pain Nausea and vomiting Precipitating factors Watching TV in a dark room Pharmacological Mydriasis Sympathetic agonist (Inhalers)

Signs

APAC Elevated IOP risen rapidly Conjunctival congestion Corneal epithelial /stromal edema Shallow or flat peripheral AC Mid dilated [vertical oval] pupil Absent /sluggish pupil reaction Fellow eye generally shows an occludable angle

Subacute Angle Closure

Resolved APAC

• Folds in Descemet membrane (if IOP has been reduced rapidly), optic nerve head congestion and choroidal folds.

• Later iris atrophy [spiral-like configuration], irregular pupil, posterior synechiae and glaukomflecken

• Iris torsion

Chronic Presentation• ‘Creeping’ angle-closure [gradual band-like anterior

advance of the apparent insertion of the iris]. From deepest part of the angle and spreads circumferentially

• Episodic (intermittent) ITC is associated with the formation of discrete PAS, individual lesions having a pyramidal (‘saw-tooth’) appearance

• Disc cupping /nerve fibre defects with or without visual field defect

Sequence Of Events• Acute angle closure sudden ,circumferential , iridotrabecular

apposition-rapid severe rise in IOP• Intermittent angle closure Self limiting episodes of ITC ,milder signs &

symptoms of former• Creeping angle closure slowly progressive ITC –Elevated IOP• Chronic angle closure irreversible , iridotrabecular

adhesion ,asymptomatic unless significant raised IOP

Investigations1. Anterior segment OCT2. Anterior chamber depth measurement3. Posterior segment USG4. Provocative tests Pharmacological test pupillary block mechanism in mid dilated state ,increased

tension of iris . Performed with short acting mydriatic [phenylephrine eye

drops] if test proves positive –acute attack may be triggered

Dark room prone test pupil dilates in dark,lens moves forwards in prone. - Patient sits for 30 minutes in dark with head

prone ,no sleeping - IOP checked rapidly ,positive if increases by 8 mm

Hg

Treatment

APACInitial Treatment1.Supine Position2. IV Acetazolamide 500mg if IOP >50mm of Hg. oral if <50mm

of Hg3.Additional oral dose of 500 mg of Acetazolamide4.Apraclonidine 0.5%-1%,timolol 0.5%,prednisolone 1%5.Pilocarpine 2-4% 1drop ½ hourly repeatedly,1% 1 drop to the

fellow eye6. Analgesic and antipyretic

Resistant case1.Central corneal indentation2.Further pilocarpine, timolol, apraclonidine, prednisolone3.Mannitol 20% IV 1-2gm/kg over 1 hr, oral glycerol 50%

1gm/kg or oral isosorbide 1gm/kg4.Paracentesis5.Clearing cornel oedeme with glycerol6.Surgical :PI, Laser iridotomy, iridoplasty, lens extraction,

goniosynechialysis,trabeculectomy

Subsequent Med Treatment1.Pilocarpine 2% 4 times to affected eye,1% 4 times to

fellow eye2.Topical steroid 4 times3.(Any of ) timolol or apraclonidine or oral acetazolamide

PACS1.Laser iridotomy2. If ITC persists –laser iridoplasty, long term pilocarpine

prophylaxis, lens extraction

PAC & PACG1.As for PACS but urgency & intensity of treatment with

frequent review with anti glaucoma medications and neuroprotective drugs.

Peripheral Laser Iridotomy• A hole is made in iris periphery allowing aqueous to drain

from PC into TM• Helps eliminate high aqueous pressure behind iris and iris

falls back.• Done using Nd:YAG laser ,150-200 microns size 3-6 mj of

power based on thickness• Topical pilocarpine 30 mins before laser therapy, identify

crypt in iris and create opening• Post op steroids and antiglaucoma meds

Surgical Peripheral Iridectomy

• Removal of iris tissue by knife or scissors• 2-3 mm peripheral corneal incision in

superotemporal site• Alternatively ,conjunctival peritomy and scleral

limbus incision wound closure• Externalised iris piece held with toothed forceps ,

incised with fine scissors