Ophthalmology – Pupillary Block Glaucoma

Basics

Description

Pupillary block is the most common mechanism of primary angle closure.

It occurs when aqueous humor encounters increased resistance while passing:

Posterior chamber → through pupil → anterior chamber

The resulting pressure differential pushes the peripheral iris anteriorly, producing:

Iris bombe → iridotrabecular contact → angle closure → elevated IOP

If prolonged or recurrent, this can lead to:

• Peripheral anterior synechiae (PAS)
• Chronic angle closure
• Glaucomatous optic neuropathy
• Permanent visual loss

Key Clinical Concept

Pupillary block is a:

Mechanism of angle closure

rather than a single disease entity.

It may occur as:

• Acute primary angle closure
• Intermittent angle closure
• Chronic primary angle closure
• Secondary pupillary block

The definitive treatment for a significant pupillary-block component is usually:

Laser peripheral iridotomy (LPI)

which creates an alternative route for aqueous from the posterior to anterior chamber.

Modern Primary Angle-Closure Classification

It is useful to distinguish:

Primary Angle-Closure Suspect (PACS)

• Iridotrabecular contact/occludable angle
• No PAS
• No elevated IOP attributable to angle closure
• No glaucomatous optic neuropathy

Primary Angle Closure (PAC)

Angle closure with evidence such as:

• PAS
• Elevated IOP

but:

• No glaucomatous optic neuropathy

Primary Angle-Closure Glaucoma (PACG)

PAC plus:

Glaucomatous optic nerve and/or visual field damage

Epidemiology

Primary angle-closure disease is more common in:

• East and Southeast Asian populations
• Inuit populations
• Older adults
• Women

It is less common in many European-derived populations.

Risk rises substantially with age because the crystalline lens:

• Thickens
• Moves anteriorly
• Crowds the anterior segment

Risk Factors

Important risk factors include:

• Increasing age
• Female sex
• Asian or Inuit ancestry
• Hyperopia
• Short axial length
• Shallow anterior chamber
• Thick or anteriorly positioned lens
• Small corneal diameter
• Family history
• Plateau iris configuration
• Nanophthalmos

Lens-Related Predisposition

The crystalline lens plays a major role in angle closure.

With age it becomes:

• Thicker
• More anteriorly positioned

This narrows the space between:

• Iris
• Lens
• Cornea

and increases resistance to aqueous movement through the pupil.

Genetics

Primary angle-closure disease has significant:

Heritability

and first-degree relatives have increased risk.

The genetics are:

• Polygenic
• Complex
• Influenced by ocular biometric traits

Routine genetic testing is not clinically useful.

Pathophysiology

Normally, aqueous humor flows:

Ciliary body → posterior chamber → pupil → anterior chamber → trabecular meshwork

In relative pupillary block:

• Iris contacts the anterior lens more tightly
• Resistance to aqueous movement through the pupil rises
• Posterior chamber pressure exceeds anterior chamber pressure
• Peripheral iris bows forward

This produces:

Iris bombe

Iris Bombe

Iris bombe is anterior convexity of the iris caused by:

Posterior chamber pressure exceeding anterior chamber pressure

The peripheral iris then contacts:

• Trabecular meshwork
• Peripheral cornea in severe cases

causing acute or chronic closure of the drainage angle.

Appositional vs Synechial Closure

Appositional Closure

The iris contacts the trabecular meshwork but:

• Can still be mechanically separated

This may reverse with:

• Indentation
• Resolution of pupillary block
• LPI

Synechial Closure

Prolonged contact causes:

Peripheral anterior synechiae

which represent permanent adhesions between iris and angle structures.

Peripheral Anterior Synechiae

PAS can lead to:

• Persistent angle closure
• Chronic IOP elevation
• Reduced response to LPI alone

Greater PAS burden generally predicts:

Greater likelihood of persistent glaucoma after LPI.

Acute Primary Angle Closure

An acute attack occurs when the angle suddenly closes extensively, causing rapid IOP elevation.

Typical symptoms include:

• Severe ocular pain
• Red eye
• Blurred vision
• Halos around lights
• Frontal headache
• Nausea
• Vomiting

This is an:

Ophthalmic emergency

Precipitating Factors

Acute angle closure may be precipitated by pupillary dilation from:

• Darkness
• Emotional stress
• Pharmacologic mydriasis
• Anticholinergic medications
• Sympathomimetic medications

The pupil is often most vulnerable in a:

Mid-dilated position

because iridolenticular contact and peripheral iris crowding increase.

Medication-Associated Angle Closure

Drugs that may trigger pupillary-block angle closure in anatomically narrow eyes include:

• Anticholinergics
• Sympathomimetics
• Some inhaled anticholinergics
• Some antidepressants through pupillary dilation

Important Modern Distinction – Topiramate

Topiramate-associated angle closure is generally caused by:

Ciliochoroidal effusion with forward rotation of the ciliary body

not pupillary block.

Typical features include:

• Bilateral acute myopic shift
• Bilateral shallow chambers
• Angle closure

Treatment involves:

• Stopping the causative medication
• Cycloplegia
• IOP lowering
• Steroids in selected cases

and:

LPI is usually ineffective because the mechanism is not pupillary block.

Secondary Pupillary Block

Pupillary block can also result from:

• 360° posterior synechiae (seclusio pupillae)
• Uveitis
• Intumescent cataract
• Spherophakia
• Lens subluxation
• Aphakia with vitreous block
• Pseudophakic pupillary block
• Silicone oil
• Gas tamponade in selected circumstances

Uveitic Pupillary Block

Inflammation can produce:

Posterior synechiae

If synechiae become circumferential:

Seclusio pupillae → iris bombe → secondary angle closure

Management may require:

• Intensive topical corticosteroids
• Cycloplegia
• LPI or surgical iridectomy

Lens Subluxation and Spherophakia

A small spherical or anteriorly displaced lens can:

• Increase iridolenticular contact
• Produce pupillary block
• Cause angle closure

Lens extraction may ultimately be required.

Clinical History

Ask about:

• Eye pain
• Halos
• Blurred vision
• Intermittent attacks in dim lighting
• Headache
• Nausea/vomiting
• Previous similar episodes
• Family history of angle closure
• Hyperopia
• Recent dilation
• New medications
• Prior uveitis
• Cataract
• Ocular surgery

Intermittent Angle Closure

Before a full acute attack, patients may report recurrent episodes of:

• Blurred vision
• Colored halos
• Brow ache
• Mild headache

especially in:

• Darkness
• Evening
• Stress

Symptoms may resolve spontaneously as the pupil constricts.

Examination in Acute Angle Closure

Typical findings include:

• Conjunctival/ciliary injection
• Corneal edema
• Very shallow peripheral anterior chamber
• Markedly elevated IOP
• Mid-dilated poorly reactive pupil
• Closed angle
• Possible anterior chamber cells
• Glaukomflecken after severe/prolonged attack

Corneal Edema

Marked IOP elevation causes endothelial dysfunction and:

Microcystic corneal edema

This may:

• Reduce visual acuity
• Produce halos
• Obscure gonioscopy
• Make LPI difficult

Pupil

The pupil is often:

• Mid-dilated
• Sluggish
• Poorly reactive

because severe IOP elevation causes:

Iris sphincter ischemia

Glaukomflecken

Glaukomflecken are small anterior subcapsular lens opacities caused by acute lens epithelial ischemic injury after a severe IOP spike.

They suggest:

Previous acute angle closure

and may remain permanently visible.

Gonioscopy

Gonioscopy is essential in the diagnosis of angle-closure disease.

Assess:

• Degree of angle narrowing
• Iridotrabecular contact
• PAS
• Pigmentation
• Plateau iris configuration
• Other secondary mechanisms

Indentation Gonioscopy

Indentation gonioscopy helps distinguish:

Appositional closure from PAS

If the angle opens with indentation:

• Closure is predominantly appositional

If it remains closed:

• PAS or another fixed structural mechanism is likely

Fellow Eye Examination

The fellow eye should be examined carefully because it often has similar:

• Biometry
• Angle anatomy
• Predisposition to acute closure

The fellow eye may require:

Prophylactic LPI if it remains anatomically occludable.

Intraocular Pressure

IOP during acute primary angle closure may become extremely high, often:

40–70 mmHg or higher

but the exact pressure varies.

Chronic PACG may have:

• Persistently elevated IOP
• Intermittent elevation
• Normal IOP between attacks

Optic Nerve Examination

After the acute attack is controlled, assess:

• Cup-to-disc ratio
• Rim thinning
• RNFL loss
• Disc hemorrhage

because the patient may already have:

Chronic glaucomatous damage.

Visual Fields

Obtain automated perimetry after:

• Cornea clears
• IOP stabilizes
• Acute symptoms resolve

to assess for:

• Arcuate defects
• Nasal step
• Advanced constriction

OCT

OCT may assess:

• RNFL
• GCIPL/GCC
• Glaucomatous optic neuropathy

Anterior segment OCT can also demonstrate:

• Angle width
• Iris configuration
• Lens-related crowding

Ultrasound Biomicroscopy

UBM is particularly useful when the mechanism is uncertain.

It can demonstrate:

• Plateau iris
• Ciliary body anatomy
• Lens position
• Ciliary body cysts
• Supraciliary effusion
• Anterior rotation of ciliary body

Provocative Testing

Historical tests include:

• Dark-room prone testing
• Pharmacologic dilation testing

These have limited diagnostic accuracy and are:

Not routinely recommended

because modern:

• Gonioscopy
• AS-OCT
• UBM

provide safer and more useful anatomic information.

Differential Diagnosis

Important alternatives include:

• Plateau iris syndrome
• Phacomorphic glaucoma
• Neovascular angle closure
• Uveitic glaucoma
• Aqueous misdirection
• Topiramate/sulfonamide-induced ciliochoroidal effusion
• Lens subluxation
• Choroidal effusion
• Suprachoroidal hemorrhage
• Posterior segment mass

Pupillary Block vs Plateau Iris

Pupillary Block

• Iris bombe
• Increased iridolenticular resistance
• Usually relieved by LPI

Plateau Iris

• Relatively flat central iris
• Anteriorly positioned ciliary processes
• Peripheral iris rises abruptly
• Angle may remain occludable despite patent LPI

Pupillary Block vs Phacomorphic Glaucoma

Phacomorphic glaucoma involves:

• Intumescent/thickened lens
• Shallow central and peripheral chamber
• Lens crowding plus pupillary block

Definitive treatment is:

Cataract extraction

after acute IOP control.

Pupillary Block vs Aqueous Misdirection

Aqueous misdirection usually causes:

• Uniformly shallow or flat central and peripheral chamber
• Often postoperative setting
• Patent iridotomy

The iris configuration is different from classic iris bombe.

Acute Treatment Goals

Management of acute primary angle closure has three goals:

1. Rapidly lower IOP
2. Reduce inflammation and symptoms
3. Eliminate pupillary block definitively

Initial Medical Therapy

Common acute treatment includes:

• Topical beta-blocker
• Topical alpha-2 agonist
• Topical carbonic anhydrase inhibitor
• Systemic acetazolamide

A typical adult acetazolamide loading dose is often:

500 mg

unless contraindicated.

Hyperosmotic Therapy

If IOP remains very high or the attack is severe, consider:

• IV mannitol
• Oral glycerol in selected patients

Hyperosmotic agents reduce vitreous volume and help:

• Deepen the anterior chamber
• Lower IOP

Use carefully in patients with:

• Heart failure
• Renal impairment
• Significant volume-status problems

Topical Steroids

Topical corticosteroids are useful because acute angle closure produces:

Significant anterior segment inflammation

They help reduce:

• Cells/flare
• Pain
• Synechial formation

Pilocarpine

Pilocarpine can constrict the pupil and pull the peripheral iris away from the angle.

However:

Do not rely on pilocarpine while IOP is extremely high.

At very high IOP:

• Iris sphincter becomes ischemic
• Pilocarpine may be ineffective

It is typically used after IOP begins to fall.

Important Pilocarpine Exceptions

Pilocarpine may be inappropriate or harmful in angle closure caused by:

• Topiramate/ciliochoroidal effusion
• Aqueous misdirection
• Certain lens-induced mechanisms

because further anterior movement or ciliary-body contraction can worsen crowding.

Analgesia and Antiemetics

Patients often require:

• Analgesics
• Antiemetics

because nausea and vomiting can be severe.

Anterior Chamber Paracentesis

Anterior chamber paracentesis can produce:

Rapid IOP reduction

and may be considered by an experienced ophthalmologist when:

• IOP is dangerously high
• Medical therapy is inadequate
• Rapid corneal clearing is needed

It is an:

Adjunct, not a substitute for definitive treatment.

Corneal Indentation

Gentle indentation of the central cornea may sometimes temporarily:

• Force aqueous toward the angle
• Open appositional closure
• Reduce IOP

This is a short-term maneuver only.

Definitive Treatment – Laser Peripheral Iridotomy

LPI is the definitive treatment for pupillary block.

The iridotomy creates a direct channel between:

• Posterior chamber
• Anterior chamber

which equalizes pressure and flattens iris bombe.

Timing of LPI

LPI should be performed once:

• IOP is sufficiently controlled
• Cornea is clear enough
• Inflammation permits safe laser treatment

Iridotomy Site

LPI is usually placed:

• Superiorly or superotemporally

under the upper lid when possible.

Modern placement is individualized to:

• Iris crypts
• Lid position
• Laser visibility

Nd:YAG and Argon Laser

Iridotomy may be performed with:

• Nd:YAG laser
• Sequential argon + Nd:YAG in thick/dark irides

depending on:

• Iris pigmentation
• Thickness
• Surgeon preference

Fellow-Eye LPI

After an acute primary angle-closure attack in one eye, the fellow eye is at substantial risk.

If the fellow eye has a narrow/occludable angle:

Prophylactic LPI is generally recommended.

LPI Complications

Potential complications include:

• Transient IOP spike
• Anterior uveitis
• Hyphema
• Corneal endothelial injury
• Dysphotopsia
• Closure of iridotomy
• Rare lens injury

Persistent Narrow Angle After LPI

A patent LPI does not guarantee that the angle becomes fully open.

Persistent narrowing may indicate:

• Plateau iris
• Large/thick lens
• PAS
• Anteriorly positioned ciliary body
• Other secondary mechanism

Laser Peripheral Iridoplasty

Argon laser peripheral iridoplasty (ALPI) contracts the peripheral iris and pulls it away from the trabecular meshwork.

It can be useful when:

• Acute closure persists
• LPI cannot initially be performed
• Plateau iris contributes
• Corneal edema makes iridotomy difficult

ALPI is usually:

Adjunctive rather than definitive for true pupillary block.

Surgical Iridectomy

Surgical peripheral iridectomy is considered when:

• Laser iridotomy cannot be performed
• Iridotomy repeatedly closes
• Significant anatomic limitations exist

Lens Extraction

Modern management increasingly recognizes the role of the lens.

Lens extraction:

• Deepens the anterior chamber
• Widens the angle
• Reduces iridolenticular contact
• Removes an important component of pupillary block

Cataract Extraction

Cataract extraction is especially appropriate when:

• Visually significant cataract is present
• Lens crowding is prominent
• Angle remains narrow after LPI
• IOP remains difficult to control
• Recurrent closure occurs

Clear Lens Extraction

In selected patients with established PAC/PACG, clear lens extraction may be considered even without visually significant cataract.

The EAGLE trial supported early lens extraction in selected patients aged ≥50 with:

• Primary angle closure with substantially elevated IOP
• Or PACG

It should not be interpreted as recommending clear-lens extraction for every PACS patient.

Goniosynechialysis

In selected eyes with relatively recent PAS, cataract extraction may be combined with:

Goniosynechialysis

to mechanically strip PAS from the trabecular meshwork.

Benefit depends on:

• Duration of PAS
• Extent of closure
• Residual trabecular function

Persistent Glaucoma After LPI

If IOP remains elevated after the pupillary-block component has been relieved, treat according to the remaining mechanism.

Options include:

• Topical medications
• Lens extraction
• Goniosynechialysis in selected cases
• Trabeculectomy
• Glaucoma drainage device
• Other glaucoma surgery

Chronic Angle-Closure Glaucoma

Patients may require a relatively low target IOP because of:

• Existing optic nerve damage
• Extensive PAS
• Reduced trabecular outflow

LPI alone may not adequately control established PACG.

Family Screening

First-degree relatives have increased risk of:

• Narrow angles
• PAC/PACG

They should have comprehensive eye examination including:

Gonioscopy when appropriate.

Follow-Up

After an acute attack or LPI, follow-up should assess:

• IOP
• Iridotomy patency
• Gonioscopy
• PAS
• Angle width
• Optic nerve
• OCT
• Visual fields

Serial Gonioscopy

Even after successful LPI:

The angle can continue to narrow over time.

Reasons include:

• Lens growth
• Plateau iris
• Progressive PAS

Therefore serial gonioscopy remains important.

Prognosis

Prognosis depends on:

• Duration of acute IOP elevation
• Peak IOP
• Extent of PAS
• Preexisting optic nerve damage
• Speed of treatment
• Residual angle function

An acute attack treated rapidly can recover excellent vision.

Prolonged untreated attacks may produce:

• Optic nerve injury
• Iris atrophy
• Corneal endothelial damage
• Lens changes
• Permanent glaucoma

Complications

Potential complications include:

• Glaucomatous optic neuropathy
• Permanent visual field loss
• PAS
• Chronic angle closure
• Optic atrophy
• Corneal endothelial damage
• Iris sphincter atrophy
• Glaukomflecken
• Central retinal vascular occlusion in severe cases

Ophthalmology Pearls

• Pupillary block is the most common mechanism of primary angle closure.
• The sequence is resistance to aqueous flow through the pupil → posterior chamber pressure rises → iris bombe → iridotrabecular contact → IOP elevation.
• Acute primary angle closure classically causes pain, red eye, blurred vision/halos, headache, nausea, corneal edema, high IOP, and a mid-dilated poorly reactive pupil.
• Indentation gonioscopy is essential for distinguishing reversible appositional closure from permanent PAS.
• Laser peripheral iridotomy is definitive treatment for the pupillary-block component because it equalizes anterior and posterior chamber pressure.
• During an acute attack, first lower IOP with aqueous suppressants ± acetazolamide ± hyperosmotic therapy, control inflammation, then perform LPI when feasible.
• Pilocarpine is often ineffective at extremely high IOP because of iris sphincter ischemia; use it after pressure begins to fall.
• A patent LPI does not guarantee a permanently open angle; persistent narrowing suggests plateau iris, lens crowding, PAS, or another mechanism.
• ALPI is a useful adjunct, especially when LPI cannot initially be performed or plateau iris contributes.
• The fellow eye after an acute primary angle-closure attack is high risk; if occludable, prophylactic LPI is generally recommended.
• Lens extraction increasingly plays an important role because it deepens the chamber and widens the angle.
• The EAGLE trial supports clear-lens extraction in selected established PAC/PACG patients, but not routine lens extraction for every asymptomatic PACS eye.
• Topiramate-induced angle closure is not pupillary block; it results from ciliochoroidal effusion, so LPI is generally ineffective.
• Even after successful LPI, continue serial gonioscopy, IOP monitoring, optic nerve/OCT assessment, and visual fields because PAS and chronic angle closure can still progress.