Difference between open angle and closed angle glaucoma, the two faces of glaucoma – Open angle vs closed angle complete explanation

👁 Open vs Closed Angle Glaucoma – What’s the Difference?

Glaucoma is a progressive optic neuropathy with visual field loss.
Depending on the configuration of the anterior chamber angle, it is classified as:

✅ Open-Angle Glaucoma (OAG)
✅ Angle-Closure Glaucoma (ACG)

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💡 Key Differences

CategoryOpen-Angle Glaucoma (OAG)Angle-Closure Glaucoma (ACG)

Angle Appearance	Appears open (grossly)	Closed due to iris obstruction (grossly)
Pathophysiology	Trabecular meshwork damage	Pupillary block or PAS
Prevalence	~90% of glaucoma cases	~10% of cases
Outflow Limitation	Microscopic blockage	Gross anatomical blockage

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🔍 Mechanisms of Angle-Closure Glaucoma

1. Pupillary Block: Iris bows forward due to blocked flow → angle closure
2. Peripheral Anterior Synechiae (PAS): Iris root adheres to cornea → blocks drainage

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🧪 Open-Angle Glaucoma Specifics

• Angle is open to the eye,
• But microscopically, trabecular meshwork is damaged
• Outflow resistance causes IOP elevation

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✅ Summary

• OAG = “open” but microscopically clogged
• ACG = “physically closed” angle by iris
• Both → ↑IOP → optic nerve damage
  ➡ Knowing the type is crucial for proper treatment