Narrow-angle glaucoma - Causes, Treatment & When to See a Doctor

```html

What is Narrow‑Angle Glaucoma?

Narrow‑angle glaucoma (also called angle‑closure glaucoma or acute primary angle‑closure glaucoma) is a type of glaucoma in which the drainage angle formed by the iris and cornea becomes too narrow or suddenly closes. This blocks the outflow of aqueous humor—the clear fluid that nourishes the front of the eye—causing a rapid rise in intra‑ocular pressure (IOP). If the pressure remains high, the optic nerve can be damaged, leading to irreversible vision loss.

Unlike the more common open‑angle glaucoma, which typically rises slowly and often has no early symptoms, narrow‑angle glaucoma can present abruptly with severe eye pain, headache, and visual disturbances. Prompt recognition and treatment are essential to preserve sight.

Common Causes

Several anatomical, medical, and environmental factors can predispose a person to a narrow‑angle configuration and precipitate an acute attack:

• Shallow anterior chamber: A naturally shallow space between the cornea and iris is the most important anatomic risk factor.
• Thickened or anteriorly positioned lens: Common in people over 50, a bulky lens pushes the iris forward.
• Hyperopia (farsightedness): Shorter eyeballs often have a more crowded anterior segment.
• Family history: Genetic predisposition increases risk; about 50 % of patients report a first‑degree relative with angle‑closure glaucoma.
• Medications that dilate the pupil: Anticholinergics, antihistamines, certain antidepressants, and some eye drops can precipitate an attack.
• Dark‑adaptation (dim lighting): Pupil dilation in low light can narrow the angle further.
• Eye trauma or surgery: Procedures that alter the anatomy of the anterior chamber, such as cataract extraction or laser iridotomy, can occasionally trigger a closure.
• Inflammatory conditions: Uveitis or iris neovascularization may cause synechiae (adhesions) that close the angle.
• Systemic diseases: Conditions that affect fluid balance (e.g., diabetes, hypertension) may indirectly increase IOP.
• Age: Risk rises sharply after age 60 because the lens continues to thicken.

Associated Symptoms

Symptoms may develop suddenly (acute attack) or gradually (chronic angle‑closure).

• Severe, aching or throbbing eye pain, often described as “the worst pain I've ever felt.”
• Headache, usually behind the affected eye.
• Blurred or hazy vision; halos around lights, especially at night.
• Redness of the eye (conjunctival injection).
• Nausea and vomiting – the pain can be so intense it triggers a vagal response.
• Mid‑dilated, non‑reactive pupil on the affected side.
• Short‑term loss of peripheral (side) vision; central vision may remain relatively intact.
• In chronic cases, gradual loss of peripheral vision without pain.

When to See a Doctor

Any of the following should prompt an urgent eye‑care visit:

• Sudden onset of intense eye pain accompanied by headache or nausea.
• Rapidly worsening blurry vision or the appearance of colored halos around lights.
• Redness of the eye plus a mid‑dilated pupil that does not respond to light.
• Vision loss that progresses over days to weeks, even if pain is absent.
• History of narrow‑angle glaucoma or known risk factors (e.g., hyperopia, family history) and new visual symptoms.

Because irreversible optic‑nerve damage can occur within hours, do not wait to seek care.

Diagnosis

Eye specialists (ophthalmologists or optometrists with glaucoma expertise) use several objective tests to confirm narrow‑angle glaucoma and to assess its severity:

1. Tonometry

Measures intra‑ocular pressure (IOP). Pressures > 21 mm Hg are concerning, but normal pressures do not rule out angle‑closure.

2. Gonioscopy

The gold‑standard exam. A tiny contact lens is placed on the cornea, allowing the clinician to view the drainage angle directly and determine how open or closed it is.

3. Slit‑lamp examination

Provides a magnified view of anterior‑segment structures, identifying corneal edema, shallow chambers, or the presence of a peripheral anterior synechiae (PAS).

4. Anterior‑segment optical coherence tomography (AS‑OCT) or Ultrasound Biomicroscopy (UBM)

Non‑invasive imaging that quantifies angle width and detects subtle anatomic changes.

5. Visual field testing (perimetry)

Assesses functional loss of peripheral vision; essential for monitoring progression.

6. Fundus examination

The optic nerve head is examined for cupping or other signs of glaucomatous damage.

7. Dilated fundus photography & OCT of the retinal nerve fiber layer

Helps document baseline optic‑nerve status and follow changes over time.

Treatment Options

Therapy aims to quickly lower IOP, relieve the angle blockage, and prevent future attacks. Both emergency and long‑term strategies are used.

Emergency (Acute) Management

• Topical medications: Beta‑blockers (timolol), alpha‑agonists (apraclonidine), prostaglandin analogs (latanoprost) and carbonic anhydrase inhibitors (brinzolamide) to lower IOP.
• Systemic medications: Oral or IV carbonic anhydrase inhibitors (acetazolamide 500 mg) and hyperosmotic agents (mannitol 1–2 g/kg) are given if pressure is critically high.
• Laser peripheral iridotomy (LPI): A tiny hole is created in the peripheral iris using a laser (typically Nd:YAG or argon). This allows alternate aqueous flow, opening the angle and preventing re‑closure.
• Surgical iridectomy: If laser iridotomy fails or is contraindicated, a surgical opening in the iris may be performed.

Chronic / Preventive Management

• Laser peripheral iridotomy (prophylactic): Recommended for eyes with narrow angles but no current attack, especially in high‑risk individuals.
• Medications to keep the pupil constricted: Pilocarpine 1–2 % drops can help maintain a wider angle, but they are used cautiously because they may worsen an acute attack if given too early.
• Intra‑ocular pressure‑lowering eye drops: Long‑term prostaglandin analogues or beta‑blockers maintain lower baseline IOP.
• Cataract extraction: Removing a thickened lens deepens the anterior chamber and is an increasingly popular definitive treatment for many patients with angle‑closure.
• Microsurgical procedures: Goniosynechialysis, trabeculectomy, or tube shunt surgery may be required if IOP remains uncontrolled despite laser and medication.

Home / Lifestyle Measures

• Avoid medications that dilate the pupil (e.g., over‑the‑counter antihistamines) unless directed by a clinician.
• Stay well‑hydrated; rapid fluid shifts can affect IOP.
• Limit activities that involve prolonged darkness (e.g., watching movies in a dark theater) if you have a known narrow angle.
• Wear sunglasses to reduce glare, which can trigger pupil dilation.

Prevention Tips

While you cannot change your genetic makeup, several steps can reduce the likelihood of an acute attack:

• Regular eye exams: Adults over 40 should have a comprehensive dilated exam at least every two years; those with risk factors may need annual gonioscopy.
• Screen for family history: Inform your eye doctor if a close relative has glaucoma.
• Promptly treat cataracts: Early cataract surgery can alleviate angle crowding.
• Medication review: Discuss all prescription and OTC drugs with your physician; ask whether they affect pupil size.
• Control systemic diseases: Manage hypertension, diabetes, and sleep apnea, which can indirectly influence ocular fluid dynamics.
• Protect eyes from trauma: Wear safety glasses during high‑risk activities.
• Limit caffeine excess: Large amounts may increase IOP in susceptible eyes.

Emergency Warning Signs

Key Takeaways

Narrow‑angle glaucoma is a vision‑threatening condition that can develop quickly and without warning. Understanding the risk factors—particularly a shallow anterior chamber, hyperopia, and a family history—helps identify those who need closer monitoring. Prompt recognition of acute symptoms, immediate evaluation by an eye‑care professional, and timely interventions such as laser peripheral iridotomy can save sight. Ongoing follow‑up, medication adherence, and lifestyle modifications further protect against future attacks.

References:

• Mayo Clinic. “Angle‑closure glaucoma.” https://www.mayoclinic.org
• National Eye Institute (NEI). “Glaucoma.” https://www.nei.nih.gov
• American Academy of Ophthalmology. “Primary Angle‑Closure Glaucoma.” https://www.aao.org
• Cleveland Clinic. “Narrow‑Angle (Acute) Glaucoma.” https://my.clevelandclinic.org
• World Health Organization. “Blindness and vision impairment.” https://www.who.int

```