Types of Glaucoma: Open-Angle vs Angle-Closure

👁 Types of Glaucoma: Open-Angle vs Angle-Closure

Glaucoma is a progressive optic neuropathy marked by:

• Structural damage to the optic nerve
• Functional loss (visual field defects)

This condition can be classified anatomically based on the status of the anterior chamber angle.

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📌 Angle-Closure Glaucoma (ACG)

• The angle between the iris and cornea is visibly closed
• Accounts for ~10% of all glaucoma
• Aqueous humor cannot drain → sudden IOP spike

Main Mechanisms

1. Pupillary Block
   • Iris comes into contact with the lens → flow is blocked at the pupil
   • Iris bows forward → closes the angle
2. Peripheral Anterior Synechia (PAS)
   • Peripheral iris adheres to cornea → angle closure

 

 

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📌 Open-Angle Glaucoma (OAG)

• The angle appears open grossly, but is functionally obstructed
• Accounts for ~90% of all glaucoma
• Microscopic trabecular meshwork dysfunction → IOP elevation

Key Feature

• Aqueous outflow is impaired due to TM resistance, not anatomical closure

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✅ Summary Table

FeatureAngle-Closure GlaucomaOpen-Angle Glaucoma

Angle appearance	Visibly closed	Visibly open
Mechanism	Pupil block / PAS	TM malfunction (microscopic)
IOP behavior	Sudden, high	Chronic, progressive
Frequency	~10%	~90%
Clinical course	Acute, emergency	Gradual, often asymptomatic