Understanding Glaucoma: Key Insights for Optometry Students and Pre-Reg Optometrists

Below is a summary of the main learning points from the webinar.

1. Classification of Glaucoma

Glaucoma can be broadly classified by onset and anatomy:

• Primary vs Secondary:
  • Primary glaucoma occurs without an identifiable underlying cause.
  • Secondary glaucoma develops as a result of another condition (e.g., trauma, steroid use, or ocular inflammation) that raises intraocular pressure (IOP).
• Open vs Closed Angle:
  The anatomy of the anterior chamber angle determines whether the condition is open or closed.
  • In open-angle glaucoma, the aqueous humour has access to the drainage angle, but outflow resistance still causes gradual optic nerve damage.
  • In closed-angle glaucoma, the aqueous cannot reach the trabecular meshwork, leading to a rapid rise in IOP, often accompanied by pain, redness, and visual disturbances such as halos.

2. Diagnosis: From Gonioscopy to Visual Fields

A solid understanding of diagnostic tools is essential in glaucoma management.

• Gonioscopy is the gold standard for evaluating the anterior chamber angle and confirming a diagnosis. While Van Herrick’s technique using the slit lamp is commonly used as a guide in practice, it should always be followed up with gonioscopy for definitive assessment.
• Optic Disc and Retinal Nerve Fibre Layer (RNFL) Examination:
  Early glaucomatous damage often presents as RNFL defects, typically visible within two disc diameters of the optic nerve head under green (red-free) light. These appear as:
  • Wedge defects, darker, wedge-shaped areas indicating focal loss.
  • Diffuse thinning, a general loss of brightness and striations.

RNFL defects occur in fewer than 3% of normal eyes, making them a strong indicator of pathology.

• Peripapillary Atrophy (PPA):
  The beta zone of PPA, found closer to the optic disc, can indicate glaucomatous damage, particularly when adjacent to areas of neuroretinal rim loss.
• Optic Disc Haemorrhages:
  Small splinter- or dot-shaped haemorrhages on or near the optic disc occur in less than 0.2% of normal eyes but are strongly associated with glaucoma progression.
• Visual Field Testing:
  While structural changes suggest glaucoma, functional confirmation comes through visual field tests. Characteristic patterns such as nasal steps or arcuate defects correlate with optic nerve damage.

3. Understanding Glaucoma Risk Factors

Developing a risk profile for each patient is vital in determining who may require closer monitoring or referral.

Key risk factors include:

• Increasing age
• Family history of ocular hypertension or glaucoma (particularly siblings)
• Thinner central corneal thickness (<555 µm)
• Myopia greater than 3 dioptres
• Long-term steroid use
• African-Caribbean or South-East Asian ethnicity
• Female sex and smaller anterior chambers, especially in hypermetropic eyes

In normal-tension glaucoma, factors such as migraine and Raynaud’s phenomenon may also play a role.

4. When to Refer

Referral decisions depend on both structural and functional findings:

• Any suspected glaucomatous optic disc changes, RNFL defects, or unexplained field loss warrant referral.
• For angle closure suspicion, Van Herrick Grade 1 or less — or any symptomatic case — should be referred urgently.
• Always tailor to local referral protocols, as these can vary by region.
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5 . The Bigger Picture: Learning Beyond the Exam

While mastering the technical aspects of glaucoma diagnosis and management is essential for your OSCEs and clinical placements, it’s equally important to develop your clinical judgment. Ask yourself:

• “Is this normal for the patient’s age and ethnicity?”
• “Has there been any change since previous exams?”
• “Do I need to act now, or should I monitor?”

Experience and confidence in making these decisions come with time — and exposure to real cases.

Final Thoughts

As you progress through your studies and pre-reg placements, remember that glaucoma care requires a blend of knowledge, observation, and patient communication. Early detection and management make a life-changing difference for patients — and your role as an optometrist is at the heart of that process.