Malignant Glaucoma (Aqueous Misdirection Syndrome)

Definition and Pathophysiology

• Forward displacement of the vitreous, lens (or IOL), and ciliary processes
• Secondary angle closure from behind (not pupillary block)

• Kanski's Clinical Ophthalmology, p. 435
• The Wills Eye Manual, p. 624

Precipitating Factors / Who Gets It

• Most commonly follows incisional surgery (cataract, trabeculectomy, retinal surgery) - particularly in eyes with small anterior segments
• Eyes predisposed: hyperopia, nanophthalmos, primary angle-closure glaucoma
• Can be triggered by miotics (which paradoxically worsen the condition)
• May occur spontaneously, without prior surgery
• Classically seen after trabeculectomy in patients with primary angle-closure glaucoma

Clinical Features

Symptoms

• May be mild early on
• Moderate pain, red eye, photophobia as it progresses
• The patient may notice improved unaided near vision (due to myopic shift from forward lens displacement)

Signs (Critical Triad)

1. Diffusely shallow or flat anterior chamber with myopic shift
2. Elevated IOP (though may not be significantly elevated early)
3. Patent peripheral iridectomy (PI) present - distinguishes from pupillary block

• Negative Seidel test (no wound leak)
• Absence of iris bombé (distinguishes from pupillary block)
• Absent bleb (post-trabeculectomy cases)
• Wills Eye Manual, p. 623

Differential Diagnosis

Workup

1. History: Previous ocular surgery?
2. Slit-lamp exam: Confirm shallow AC, look for patent PI; rule out iris bombé
3. Gonioscopy and IOP measurement
4. Dilated fundus exam (unless phakic angle closure likely)
5. B-scan ultrasound to rule out choroidal detachment and suprachoroidal hemorrhage
6. Seidel test to exclude wound leak

Treatment

Step 1 - Ensure Patent PI

Step 2 - Medical Therapy (First Line)

• Cycloplegia/mydriasis: Atropine 1% + phenylephrine 2.5% qid topically - dilates the ciliary ring, increases the distance between ciliary processes and lens equator, tightens zonules, and pulls the lens posteriorly
• Systemic CAI: Acetazolamide 500 mg IV or 500 mg PO
• Topical beta-blocker: Timolol 0.5% daily or BID
• Topical alpha-2 agonist: Apraclonidine 1% or brimonidine 0.1%-0.2% BID
• Hyperosmotic agent: Mannitol 20% (1-2 g/kg IV over 45 min) if needed - shrinks vitreous and draws the lens posteriorly

Important: Miotics are absolutely contraindicated - they worsen aqueous misdirection by rotating the ciliary body further anteriorly.

Step 3 - Laser Therapy (if medical therapy fails)

• Nd:YAG laser through the iridectomy to disrupt the anterior hyaloid face
• In pseudophakic eyes: laser posterior capsulotomy + disruption of anterior hyaloid face
• In aphakic eyes: YAG disruption of anterior hyaloid face and posterior capsule
• Cyclodiode laser to the ciliary processes may also be effective
• Argon laser of the ciliary processes (alternative)

Step 4 - Surgical Therapy (if laser fails)

• Pars plana vitrectomy - removal of sufficient anterior vitreous to allow free aqueous flow to the anterior chamber; goal is to create a "unicameral eye"
• Pars plana vitrectomy + irido-zonulo-hyaloidectomy: combined excision of iris, lens capsule, zonules, and anterior hyaloid face
• Lensectomy with disruption of anterior hyaloid

Note: An undetected anterior choroidal detachment may coexist, so sclerotomy to drain choroidal detachment may be considered before vitrectomy.

Follow-Up

• Timing depends on the treatment modality used
• Peripheral iridectomy should be performed in the contralateral eye (if the angle is occludable) within one week of treatment of the affected eye

Key Mnemonic Summary

• Kanski's Clinical Ophthalmology (10th ed.), p. 435
• The Wills Eye Manual, pp. 623-625