Overview
Acute Angle-Closure Glaucoma
1. Clinical Overview
Summary
Acute angle-closure glaucoma (AACG) is an ophthalmic emergency with sudden IOP elevation (40-80 mmHg) from iris blocking aqueous drainage. Classic triad: severe eye pain, halos, fixed mid-dilated pupil. Treat with topical timolol + apraclonidine, IV acetazolamide, then pilocarpine. Urgent ophthalmology for laser iridotomy.
Key Facts
- Definition: Sudden IOP elevation from iris blocking trabecular meshwork
- IOP: Typically 40-80 mmHg (normal 10-21)
- Treatment: Multi-drug approach + laser peripheral iridotomy
- Time-critical: Permanent vision loss within hours if untreated
2. Epidemiology
Acute angle-closure glaucoma (AACG) is an ophthalmic emergency characterized by sudden, marked elevation of intraocular pressure (IOP) due to physical blockage of the trabecular meshwork drainage pathway by the peripheral iris. This results from pupillary block where aqueous humor cannot flow from the posterior to the anterior chamber, causing forward bowing of the iris against the cornea and closing the drainage angle.
Epidemiology
- Incidence: 0.5-1 per 1,000 population per year
- Age: Most common in older adults (peak 55-70 years)
- Sex: More common in women (3-4:1 ratio)
- Ethnicity: Higher incidence in Asians (especially East Asians), Inuit populations
- Refractive error: More common in hyperopes (farsighted individuals)
Classification
| Type | Description |
|---|---|
| Primary AACG | Pupillary block in anatomically predisposed eye |
| Secondary AACG | Underlying pathology (lens swelling, tumor, medications) |
| Chronic angle closure | Gradual closure without acute episodes |
| Intermittent angle closure | Episodic attacks that resolve spontaneously |
3. Pathophysiology
Anatomical Predisposition
Certain anatomical features predispose to angle closure:
- Short axial length (hyperopic eye)
- Shallow anterior chamber (<2.5mm central depth)
- Thick crystalline lens (increases with age)
- Anteriorly positioned lens
- Small corneal diameter
- Narrow iridocorneal angle
Mechanism of Attack
Pupillary Block Sequence
- Mid-dilated pupil creates maximum iris-lens contact
- Aqueous humor trapped behind iris
- Posterior-to-anterior chamber pressure differential
- Iris bows forward (iris bombé)
- Peripheral iris apposes trabecular meshwork
- Aqueous outflow blocked → IOP rises rapidly
Triggers for Attack
- Dim lighting (pupil dilation)
- Emotional stress
- Medications (anticholinergics, sympathomimetics)
- Post-operative mydriasis
- Acute angle closure on instillation of mydriatic drops
Consequences of Elevated IOP
Corneal Effects
- Epithelial and stromal edema
- Decreased visual acuity
- Halos around lights (from light diffraction)
Anterior Segment Effects
- Iris ischemia (fixed, mid-dilated pupil)
- Trabecular meshwork damage
Posterior Segment Effects
- Optic nerve ischemia
- Retinal ganglion cell death
- Permanent vision loss if prolonged
Time-Dependent Damage
| Duration | Risk of Permanent Damage |
|---|---|
| <2 hours | Low (usually reversible) |
| 2-6 hours | Moderate |
| 6-24 hours | High |
| >4 hours | Very high (often irreversible) |
4. Clinical Presentation
Classic Presentation
Symptoms
Signs
Atypical Presentations
Intermittent Attacks
Subacute Presentation
Chronic Angle Closure
Associated Findings
History Red Flags
Severe, unilateral eye pain (throbbing, aching)
Common presentation.
Decreased vision (may be profound)
Common presentation.
Halos around lights (from corneal edema)
Common presentation.
Frontal headache (often ipsilateral)
Common presentation.
Nausea and vomiting (vagal response to severe pain/IOP)
Common presentation.
Photophobia
Common presentation.
5. Clinical Examination
(Integrated into Clinical Presentation and Diagnostic sections)
Red Flags (Vision-Threatening)
Vision-Threatening Features
| Red Flag | Significance | Action |
|---|---|---|
| IOP >0 mmHg | Severe attack | Aggressive IOP lowering, urgent ophthalmology |
| Duration > hours | High damage risk | Emergent ophthalmology, consider surgical intervention |
| No pupil response | Iris ischemia | Poor prognostic sign, aggressive treatment |
| Hand motions vision | Severe attack | Maximum medical therapy |
| Corneal opacification | Severe edema | Indicates prolonged elevated IOP |
| Previous attack to fellow eye | Very high risk | Prophylactic treatment needed |
Medications That Can Precipitate Attack
Anticholinergics
- Atropine, cyclopentolate (eye drops)
- Scopolamine, glycopyrrolate (systemic)
- Antihistamines, antipsychotics
- Tricyclic antidepressants
Sympathomimetics
- Phenylephrine (topical, systemic)
- Epinephrine, norepinephrine
- Decongestants (pseudoephedrine)
- Amphetamines
Others
- Topiramate
- Sulfas-containing drugs
- Selective serotonin reuptake inhibitors (SSRIs)
- Botulinum toxin (facial injections)
6. Investigations
Differential Diagnosis
| Condition | Key Distinguishing Features |
|---|---|
| Acute anterior uveitis | Miotic pupil, cells/flare in anterior chamber, normal/low IOP |
| Corneal ulcer/keratitis | Focal corneal defect on fluorescein, discharge |
| Conjunctivitis | No vision loss, normal pupil, normal IOP, discharge |
| Cluster headache | Ipsilateral autonomic features, normal eye exam |
| Migraine | Neurological symptoms, normal eye exam, normal IOP |
| Scleritis/episcleritis | Deep tenderness, normal or near-normal IOP |
| Neovascular glaucoma | Rubeosis iridis, diabetes/CRVO history, elevated IOP |
| Traumatic iritis | History of trauma, cells in anterior chamber |
| Phacolytic glaucoma | Mature cataract visible, elevated IOP |
Key Differentiating Physical Exam Features
| Feature | AACG | Uveitis | Conjunctivitis |
|---|---|---|---|
| Pupil | Mid-dilated, fixed | Miotic | Normal |
| IOP | Very elevated (40-80) | Normal or low | Normal |
| Cornea | Cloudy, edematous | Clear or slight haze | Clear |
| Anterior chamber | Shallow | Cells/flare present | Normal |
| Discharge | None | None | Present |
| Vision | Decreased | May be decreased | Normal |
Diagnostic Approach
Initial Assessment
History
- Onset and duration of symptoms
- Precipitating factors (medications, dim light)
- Previous similar episodes
- Eye history (refractive error, previous surgeries)
- Medical history (diabetes, cardiovascular disease)
- Current medications
Physical Examination
- Visual acuity (each eye separately)
- Pupil examination (size, reactivity)
- External eye examination (injection pattern)
- Corneal clarity
- Anterior chamber depth (penlight test)
- Globe firmness (through closed lid)
Diagnostic Tests
Essential Tests
| Test | Findings in AACG |
|---|---|
| Tonometry | IOP 40-80 mmHg (markedly elevated) |
| Visual acuity | Reduced, may be counting fingers or worse |
| Pupil examination | Mid-dilated (4-6mm), fixed, minimally reactive |
| Penlight test | Shallow anterior chamber (see below) |
| Fluorescein staining | Diffuse punctate staining from corneal edema |
Penlight (Van Herick) Test
- Shine light tangentially from temporal side
- In normal eye: Anterior chamber depth > ¼ corneal thickness
- In narrow angle: Anterior chamber depth < ¼ corneal thickness
- If peripheral iris shadows nasal cornea, angle is likely narrow
Slit-lamp Examination (if available)
- Corneal epithelial and stromal edema
- Shallow anterior chamber centrally and peripherally
- Mid-dilated, fixed pupil
- Iris may appear atrophic (spiral/sector atrophy if ischemic)
- May see cellular reaction in anterior chamber
Gonioscopy
- Definitive test for angle anatomy
- Performed by ophthalmologist
- May not be possible if cornea very cloudy
Assessing the Fellow Eye
Critical step: The fellow eye often has similar anatomy and is at high risk for an attack.
- Check anterior chamber depth
- Measure IOP
- Examine pupil response
- Document findings for ophthalmology
7. Management
Immediate Management Algorithm
Acute Angle-Closure Glaucoma Confirmed
↓
Step 1: Position patient supine
(helps move lens posteriorly)
↓
Step 2: Topical therapy (affected eye)
- Timolol 0.5% x1 drop
- Apraclonidine 1% x1 drop
(Do NOT give pilocarpine initially -
ischemic iris won't respond)
↓
Step 3: Systemic IOP reduction
- Acetazolamide 500mg IV
OR
- Acetazolamide 250-500mg PO if no IV
↓
Step 4: Support care
- IV access and fluids
- Antiemetics (ondansetron 4mg IV)
- Analgesia (morphine if needed)
↓
Step 5: After 30-60 minutes (when IOP begins to drop)
- Pilocarpine 2% every 15 min x 3
(Constricts pupil, opens angle)
↓
Step 6: If refractory (IOP still very elevated)
- IV Mannitol 1-2 g/kg over 45 min
↓
Step 7: Urgent ophthalmology consultation
- Laser peripheral iridotomy (definitive)
Pharmacotherapy Details
Topical Medications
| Medication | Mechanism | Dose | Notes |
|---|---|---|---|
| Timolol 0.5% | Decreases aqueous production | 1 drop | Caution in asthma, bradycardia |
| Apraclonidine 1% | Decreases aqueous production | 1 drop | Alternative: Brimonidine 0.2% |
| Pilocarpine 2% | Constricts pupil, opens angle | 1 drop q15min x3 | Only after IOP starts to decrease |
| Dorzolamide 2% | Carbonic anhydrase inhibitor | 1 drop | Additional topical option |
Systemic Medications
| Medication | Mechanism | Dose | Notes |
|---|---|---|---|
| Acetazolamide | Carbonic anhydrase inhibitor | 500mg IV or PO | Avoid in sulfa allergy, renal disease |
| Mannitol 20% | Osmotic agent | 1-2 g/kg IV over 45 min | Refractory cases; avoid in CHF, renal failure |
| Glycerol | Oral osmotic agent | 1-1.5 g/kg PO | Alternative if no IV; avoid in diabetics |
| Isosorbide | Oral osmotic agent | 1-1.5 g/kg PO | Does not affect blood glucose |
Definitive Treatment
Laser Peripheral Iridotomy (LPI)
- Definitive treatment for pupillary block
- Creates alternate pathway for aqueous flow
- Usually performed once IOP controlled
- Also performed prophylactically on fellow eye
Surgical Options
- Surgical iridectomy if laser not possible
- Lens extraction (lensectomy) may be considered
- Trabeculectomy for persistent IOP elevation
Special Considerations
When Pilocarpine Won't Work
- Ischemic iris (IOP very high for prolonged period)
- Lens-induced angle closure (needs lens extraction)
- Plateau iris configuration (different mechanism)
- Neovascular glaucoma (treat underlying cause)
Contraindications to Medications
| Medication | Contraindications |
|---|---|
| Timolol | Bradycardia, heart block, asthma, COPD |
| Acetazolamide | Sulfa allergy, renal failure, severe hypokalemia |
| Mannitol | CHF, anuria, pulmonary edema |
| Pilocarpine | Uveitis, neovascular glaucoma |
8. Complications
Disposition
Ophthalmology Consultation
Emergent Consultation (same day)
- All confirmed cases of AACG
- Refractory to medical management
- IOP not decreasing after 1-2 hours of treatment
- Severe vision impairment
Timing of Definitive Treatment
- Laser iridotomy typically within 24-48 hours
- May be same day if IOP controlled and ophthalmologist available
- Fellow eye should receive prophylactic iridotomy
Admission Criteria
Indications for Admission
- Refractory IOP elevation despite maximum medical therapy
- Need for IV mannitol (monitor fluid status)
- Significant comorbidities (cardiac, renal)
- Unable to arrange urgent ophthalmology follow-up
- Complications (persistent corneal edema, uncertain diagnosis)
Discharge Criteria
Safe for Discharge
- IOP <30 mmHg and stable
- Pain controlled
- Ophthalmology follow-up within 24 hours guaranteed
- Reliable patient/family
- Clear understanding of medications and warning signs
Discharge Medications
- Continue prescribed topical medications
- Oral acetazolamide 250mg every 6-8 hours if prescribed
- Analgesics as needed
- Antiemetics as needed
Follow-up Requirements
| Priority | Timeline | Purpose |
|---|---|---|
| Ophthalmology | Within 24 hours | Laser iridotomy, IOP check |
| Emergency department | If worsening symptoms | Treatment failure |
| Post-iridotomy | 1-2 weeks | Assess angle, IOP |
| Long-term | Every 3-6 months | Monitor for chronic glaucoma |
11. Patient/Layperson Explanation
Understanding the Condition
- Acute angle-closure glaucoma is an eye emergency
- Fluid in your eye cannot drain properly, causing dangerous pressure
- Without treatment, permanent vision loss can occur
- Treatment aims to lower the pressure and prevent recurrence
Medication Instructions
- Apply eye drops exactly as prescribed
- Wait 5 minutes between different drops
- Gentle pressure at the inner corner of eye after drops
- Do not stop medications without ophthalmologist approval
- Take oral medications with food if stomach upset
Prevention of Recurrence
Avoid triggers:
- Dim lighting for prolonged periods
- Over-the-counter cold medications with anticholinergics
- Medications that dilate pupils (check with doctor first)
After iridotomy:
- Risk of recurrence is very low
- Still need regular eye exams
- Fellow eye should also be treated
Warning Signs to Return
- Return immediately if:
- Eye pain returns or worsens
- Vision decreases
- Halos around lights return
- Nausea/vomiting returns
- Headache worsens
Long-term Outlook
- With prompt treatment, vision can usually be preserved
- Laser iridotomy is usually curative for this type of glaucoma
- Regular follow-up is essential
- Some patients may develop chronic glaucoma requiring ongoing treatment
9. Prognosis & Outcomes
Special Populations
Elderly Patients
- Higher risk due to larger lens, shallower anterior chamber
- May present with atypical symptoms (confusion, systemic illness)
- Consider comorbidities when prescribing (β-blockers, carbonic anhydrase inhibitors)
- Higher risk of complications from osmotic agents
Pediatric Considerations
- AACG rare in children
- Secondary causes more common (lens dislocation, uveitis, tumors)
- Involves different anatomical considerations
- Requires pediatric ophthalmology consultation
Pregnant Patients
Medication Safety
| Medication | Pregnancy Considerations |
|---|---|
| Timolol | Category C; use if benefit > risk |
| Brimonidine | Category B; preferred topical |
| Pilocarpine | Category C |
| Acetazolamide | Category C; avoid in first trimester |
| Mannitol | Category C; use cautiously |
- Coordinate care with obstetrics
- Use minimum effective medications
- Definitive treatment (laser iridotomy) can proceed
Patients of Asian Descent
- Higher prevalence of AACG
- May have different angle anatomy (plateau iris more common)
- Lower threshold for screening and prophylaxis
- Consider cultural/language considerations in education
Quality Metrics
Performance Indicators
| Metric | Target |
|---|---|
| Time to IOP measurement | <15 minutes of presentation |
| Time to initial treatment | <30 minutes of diagnosis |
| Ophthalmology consultation | 100% of confirmed cases |
| Documentation of IOP | 100% |
| Fellow eye examination | 100% |
| Appropriate medication selection | >5% |
Documentation Requirements
- Pre-treatment visual acuity (both eyes)
- Pupil size and reactivity (both eyes)
- IOP measurement (both eyes)
- Medications administered (timing and response)
- Post-treatment IOP
- Ophthalmology consultation documentation
- Disposition plan and follow-up instructions
10. Evidence & Guidelines
Key Clinical Pearls
Diagnostic Pearls
- Triad: Eye pain + halos + mid-dilated fixed pupil = AACG until proven otherwise
- Penlight test can quickly screen for shallow anterior chamber
- Firm globe on palpation (through closed lid) suggests high IOP
- Check both eyes - fellow eye usually has similar anatomy
- Consider in patients presenting with headache/vomiting - examine the eyes!
Treatment Pearls
- Position supine - allows lens to fall back, may help open angle
- Pilocarpine won't work initially - ischemic iris sphincter cannot constrict
- Multi-drug approach is necessary - different mechanisms
- Acetazolamide IV works faster than oral
- Mannitol reserved for refractory cases - monitor fluid status
Disposition Pearls
- All patients need ophthalmology - either emergent or within 24 hours
- Laser iridotomy is definitive - usually done once IOP controlled
- Treat the fellow eye prophylactically - high risk of attack
- Education on trigger avoidance is essential
- Document pre- and post-treatment IOP for ophthalmology
12. References
- Prum BE, et al. Primary Angle Closure Preferred Practice Pattern Guidelines. Ophthalmology. 2016;123(1):P1-P40.
- Wright C, et al. Primary angle-closure glaucoma: an update. Acta Ophthalmol. 2016;94(3):217-225.
- Sun X, et al. Primary angle closure glaucoma: What we know and what we don't know. Prog Retin Eye Res. 2017;57:26-45.
- Weinreb RN, et al. Primary open-angle glaucoma. Lancet. 2014;383(9925):1402-1412.
- Ramesh S, et al. Emergency management of acute primary angle closure. J Curr Glaucoma Pract. 2015;9(3):68-72.
- AAO Preferred Practice Pattern Committee. Primary Angle Closure PPP. American Academy of Ophthalmology. 2020.
Version History
| Version | Date | Changes |
|---|---|---|
| 1.0 | 2025-01-15 | Initial comprehensive version with 14-section template |