Open-Angle vs Angle-Closure Glaucoma: Key Differences

Open-angle vs angle-closure glaucoma is the first distinction to make in any patient with raised pressure.

The two forms differ in mechanism, risk groups and treatment.

Gonioscopy separates them reliably.

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Mechanism of Open-Angle Glaucoma

The drainage angle is open, but outflow is reduced.

Resistance sits in the trabecular meshwork.

Pressure rises slowly over years.

Therefore, it is usually silent (see primary open-angle glaucoma).

Mechanism of Angle-Closure Glaucoma

The iris blocks the trabecular meshwork.

Pupillary block is the commonest cause.

Plateau iris and lens factors also contribute.

So pressure may rise suddenly.

Open-Angle vs Angle-Closure: Who Is at Risk

Open-angle disease is common in older adults and people of African ancestry.

Angle closure is more common in Asian populations and hyperopic eyes.

Women are affected more often.

Also family history matters in both.

Open-Angle vs Angle-Closure: Symptoms

Open-angle glaucoma causes no symptoms until late.

Acute angle closure causes severe pain, halos and vomiting.

Subacute episodes cause brief blur and headaches.

Therefore, ask about halos around lights.

Open-Angle vs Angle-Closure: Signs

Open-angle eyes have normal-looking anterior chambers and open angles.

Angle-closure eyes have shallow chambers and narrow angles.

Acute attacks show a fixed mid-dilated pupil and corneal edema.

So check the chamber depth in every patient.

Open-Angle vs Angle-Closure: Why Gonioscopy Decides

Gonioscopy views the angle structures directly.

It is the reference test for separating the two forms.

Without it, closure may be missed.

Also repeat it as the lens changes with age.

Imaging Open-Angle vs Angle-Closure Eyes

Anterior segment OCT shows angle width without contact.

Ultrasound biomicroscopy shows the ciliary body.

These tools help but do not replace gonioscopy.

Therefore, combine them with clinical examination.

Open-Angle vs Angle-Closure: Optic Nerve

Both forms cause cupping and rim loss.

In acute closure, the disc may be swollen at first.

Chronic closure causes slow cupping.

So disc findings do not separate them.

Treatment of Open-Angle Glaucoma

Start with drops such as prostaglandin analogues.

Add laser trabeculoplasty or surgery as needed.

The goal is to lower pressure to target.

Also review regularly (see glaucoma eye drops).

Treatment of Angle-Closure Glaucoma

Laser peripheral iridotomy relieves pupillary block.

Lens extraction is increasingly used.

Acute attacks need medical therapy first.

Therefore, treat the cause as well as the pressure.

Angle Closure Suspects

Narrow angles without damage are called suspects.

The ZAP trial suggested low progression risk.

Many clinicians still treat selected eyes (see primary angle closure suspect).

So discuss options with the patient.

Dilation in Open-Angle vs Angle-Closure Eyes

Dilation can trigger an attack in narrow angles.

Assess the angle before dilating.

Warn patients about the symptoms of acute closure.

Also give them an emergency contact.

Pitfalls to Avoid

• Do not dilate before checking the angle
• Never treat all raised pressure as open-angle disease
• Avoid skipping gonioscopy
• Do not forget to repeat gonioscopy over time

Open-Angle vs Angle-Closure Glaucoma and Medication

Some drugs trigger angle closure in susceptible eyes.

Topiramate and anticholinergics are examples (see topiramate angle closure).

Because the effect is rapid, ask about new medicines.

Then manage the attack urgently.

Open-Angle vs Angle-Closure Glaucoma in Cataract

A thick lens narrows the angle with age.

When cataract surgery is planned, it can open the angle.

Because the lens drives closure, extraction is often curative.

Therefore, consider early surgery in narrow angles.

Open-Angle vs Angle-Closure Glaucoma and Drops

Miotics help angle closure but can worsen some mechanisms.

In open-angle disease, prostaglandin analogues dominate.

Because the two forms respond differently, confirm the type first.

Then choose the drugs.

Open-Angle vs Angle-Closure Glaucoma and Follow-Up

Angle closure needs repeat gonioscopy after treatment.

Open-angle disease needs regular fields and OCT.

Because both forms can progress, follow them closely.

Therefore, plan visits by type.

Open-Angle vs Angle-Closure Glaucoma Prognosis

Acute attacks can blind within days if untreated.

Open-angle disease progresses slowly but silently.

Because outcomes depend on timing, educate patients.

Then reinforce attendance at every visit.

Open-Angle vs Angle-Closure: Practical Summary

Always examine the angle before labeling the glaucoma.

If the angle is narrow, think of closure and treat the block.

Because both forms need long-term care, schedule follow-up.

Finally, teach patients the symptoms of an acute attack.

Open-Angle vs Angle-Closure Glaucoma: Patient Advice

Explain which form the patient has and why it matters.

If the angle is narrow, mention the symptoms of an acute attack.

Because early care saves vision, give a clear emergency plan.

Finally, encourage family members to be examined.

For the latest studies, see the PubMed results for open-angle vs angle-closure.

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References

1. Weinreb RN, Aung T, Medeiros FA. The pathophysiology and treatment of glaucoma: a review. JAMA. 2014;311:1901-1911.
2. Sun X, Dai Y, Chen Y, et al. Primary angle closure glaucoma: what we know and what we don’t know. Prog Retin Eye Res. 2017;57:26-45.
3. Foster PJ, Buhrmann R, Quigley HA, Johnson GJ. The definition and classification of glaucoma in prevalence surveys. Br J Ophthalmol. 2002;86:238-242.
4. Gedde SJ, Chen PP, Heuer DK, et al. Primary angle-closure disease preferred practice pattern. Ophthalmology. 2021;128:P30-P70.