Secondary Angle-Closure Glaucomas

Secondary Angle-Closure Glaucomas - Angle Antagonists

• Definition: Trabecular meshwork (TM) obstruction; angle directly compromised by identifiable factors.
• Mechanisms:
  • Anterior Pulling (Membranes):
    • Neovascular Glaucoma (NVG): Fibrovascular membrane (FVM) contracts, zippering angle. Causes: PDR, CRVO, OIS.
    • ICE Syndromes: Corneal endothelium membrane over angle.
    • Peripheral Anterior Synechiae (PAS): Chronic uveitis, post-op.
  • Posterior Pushing (Direct Obstruction):
    • Ciliary Body Swelling/Rotation: Topiramate, uveal effusion.
    • Phacomorphic Glaucoma: Large lens crowds angle.
    • Tumors/Cysts: Iris/ciliary body masses obstruct.

⭐ NVG: Rubeosis iridis precedes angle neovascularization. 90-day glaucoma classic post-CRVO.

Secondary Angle-Closure Glaucomas - Behind The Scenes Push

• Posterior segment pathology or lens changes displace iris-lens diaphragm anteriorly, narrowing/closing the angle.
• Key Mechanisms & Causes (Posterior Push):
  • Lens-induced (Phacomorphic):
    • Intumescent cataract (swollen lens).
    • Subluxated/dislocated lens.
  • Ciliary Body Swelling/Anterior Rotation:
    • Uveitis (e.g., Vogt-Koyanagi-Harada, posterior scleritis).
    • Drugs (e.g., topiramate, sulfonamides 📌 SulfaTop).
    • Choroidal effusion/hemorrhage.
    • Tumors (ciliary body/choroidal).
  • Aqueous Misdirection (Malignant Glaucoma):
    • Posterior aqueous diversion; often post-op.
  • Post-Retinal Surgery:
    • Scleral buckle, intravitreal gas/oil.
  • Nanophthalmos: Anatomical predisposition.

⭐ Aqueous misdirection classically presents with a uniformly shallow anterior chamber and high IOP, often post-trabeculectomy.

Secondary Angle-Closure Glaucomas - Frontal Assault & Blockade

• Anterior Pulling (No Pupillary Block): Iris pulled into TM, closing angle.
  • Neovascular Glaucoma (NVG): Membrane contraction (rubeosis iridis).
  • ICE Syndrome: Endothelial membrane contracts iris.
  • Epithelial/Fibrous downgrowth: Post-trauma/surgery.
  • PAS: Post-inflammation/trauma.
• Pupillary Block: Aqueous flow obstructed at pupil.
  • Phacomorphic: Swollen lens (intumescent cataract).
  • Ectopia Lentis: Subluxated/dislocated lens.
  • Aphakic/Pseudophakic block: Vitreous/IOL.
  • Seclusio Pupillae: 360° posterior synechiae (uveitis).
  • Silicone oil.

⭐ NVG: rubeosis iridis & angle neovessels are key; linked to retinal ischemia (PDR, CRVO).

Secondary Angle-Closure Glaucomas - Spotting The Closure

• Clinical Clues:
  • Symptoms: Acute pain, blurred vision, halos, N/V (if IOP ↑↑).
  • Signs: Corneal edema, shallow AC, mid-dilated pupil, ↑IOP.
• Diagnostic Steps:
  • Gonioscopy: Essential to see Peripheral Anterior Synechiae (PAS) & angle status.
    • Indentation gonioscopy: Differentiates appositional vs. synechial closure.
  • Ultrasound Biomicroscopy (UBM): Visualizes angle structures if cornea hazy; ciliary body assessment.
  • Slit-lamp exam: Detailed anterior segment evaluation.

⭐ Gonioscopy is indispensable for diagnosing angle closure, revealing Peripheral Anterior Synechiae (PAS) which confirm synechial closure.

Secondary Angle-Closure Glaucomas - Unblocking The Path

• Causes: Uveitis, neovascular (NVG), lens-induced (phacomorphic, phacolytic), trauma, tumors, drugs (e.g., topiramate).
• Mechanisms:
  • Anterior pulling (e.g., peripheral anterior synechiae (PAS), membranes).
  • Posterior pushing (e.g., swollen lens, ciliary body edema/rotation).
• Treatment Focus:
  • Crucially, treat the primary underlying pathology first.
  • Aggressively ↓IOP: Medical (aqueous suppressants; ⚠️ avoid miotics in pupillary block/phacomorphic), Laser (LPI if pupillary block present), Surgery (filtration, GDDs).

⭐ Neovascular glaucoma (NVG), often due to Proliferative Diabetic Retinopathy (PDR) or Central Retinal Vein Occlusion (CRVO), is a common, aggressive SACG.

High‑Yield Points - ⚡ Biggest Takeaways

• Neovascular glaucoma (NVG): severe SACG, often from PDR/CRVO.
• Uveitic glaucoma: inflammation causes synechiae (PAS/PS) or pupillary block.
• Lens-induced: Phacomorphic (swollen lens), phacolytic (leaking proteins), lens subluxation/dislocation.
• Aqueous misdirection (malignant glaucoma): posterior aqueous diversion, shallow AC.
• ICE syndromes: progressive angle closure by abnormal corneal endothelium.
• Epithelial/Fibrous downgrowth: post-surgery/trauma, obstructs angle.
• Management: Treat underlying cause and aggressively lower IOP.