What Happens During a Glaucoma Eye Exam?

A glaucoma eye exam is a thorough series of tests designed to detect damage to the optic nerve and assess your risk of vision loss. Early detection and treatment can slow or prevent irreversible vision loss, so understanding what to expect can help you feel more prepared and in control.

Why a Glaucoma Eye Exam Matters

• Glaucoma is often called the “silent thief of sight” because it can progress without symptoms until significant vision loss has occurred.
• Regular glaucoma screenings are recommended if you have any of the following risk factors:
  • Family history of glaucoma
  • African, Hispanic or Asian heritage
  • High eye pressure (ocular hypertension)
  • Thin corneas
  • Chronic steroid use
  • Diabetes or high blood pressure

Key Components of a Glaucoma Eye Exam

A comprehensive glaucoma eye exam generally includes the following steps:

1. Patient History and Symptom Review
2. Visual Acuity Test
3. Intraocular Pressure Measurement (Tonometry)
4. Corneal Thickness Measurement (Pachymetry)
5. Examination of the Drainage Angle (Gonioscopy)
6. Optic Nerve Assessment
7. Visual Field Testing
8. Imaging of the Optic Nerve and Retinal Nerve Fiber Layer

Each component provides unique information about your eye health and glaucoma risk.

---

1. Patient History and Symptom Review

Your ophthalmologist or optometrist will begin by asking about:

• Any vision changes (blurriness, halos around lights, patchy vision)
• Eye pain or redness
• Use of medications, especially steroids
• General health conditions (diabetes, hypertension)
• Family history of glaucoma or other eye diseases

This conversation helps tailor the exam to your individual needs and identify risk factors.

---

2. Visual Acuity Test

• Purpose: Measures how well you see at near and far distances.
• Process: You read letters or symbols on a chart (Snellen chart).
• What to Expect: No discomfort—just covering one eye at a time and reading aloud.

---

3. Intraocular Pressure Measurement (Tonometry)

• Purpose: High intraocular pressure (IOP) is a major risk factor for glaucoma.
• Types:
  • Goldmann applanation tonometry (the gold standard)
  • Non-contact “air puff” tonometry
• Process:
  • Goldmann: A small probe gently touches the eye after numbing drops.
  • Air puff: A quick puff of air flattens the cornea briefly.
• What to Expect:
  • Goldmann: Mild pressure sensation, no pain (numbing drops used).
  • Air puff: A surprising but harmless puff of air.

---

4. Corneal Thickness Measurement (Pachymetry)

• Purpose: Corneal thickness affects IOP readings. Thicker or thinner corneas can lead to over- or underestimation of eye pressure.
• Process: A handheld ultrasound probe or non-contact device touches or scans the cornea.
• What to Expect: A brief touch (with numbing drops if needed) or scan; painless and quick.

---

5. Examination of the Drainage Angle (Gonioscopy)

• Purpose: Determines if fluid drainage channels in the eye are open or blocked.
• Process:
  • A special lens (gonio lens) is placed gently on the eye after numbing drops.
  • The doctor views the angle where the iris meets the cornea under a slit lamp microscope.
• What to Expect: Mild pressure, no pain due to numbing drops; takes a few minutes.

---

6. Optic Nerve Assessment

• Purpose: Detects structural damage to the optic nerve head—an early sign of glaucoma.
• Methods:
  • Direct examination with a slit lamp and special lens.
  • Fundus photography for documentation.
• What to Expect: Bright light; you’ll need to focus straight ahead while the doctor examines each eye.

---

7. Visual Field Testing

Visual field tests check for “blind spots” in your peripheral (side) vision. Two common methods:

• Standard Automated Perimetry (SAP)

  • Reference: Kim JM, Park KH & Kim H. (2005). SAP remains the clinical standard for mapping sensitivity across the visual field.
  • Process: You look into a bowl-shaped machine and press a button whenever you see a light stimulus.
  • What to Expect: Quiet room; test lasts about 5–10 minutes per eye.

• Frequency Doubling Technology (FDT)

  • Reference: Kim JM, Park KH & Kim H. (2005). FDT may detect early glaucomatous changes faster in some patients.
  • Process: Similar to SAP but uses flickering bars, making the test faster.
  • What to Expect: Test takes about 2–3 minutes per eye; you’ll press a button when lights appear.

Both tests are non-invasive, painless, and require minimal effort—just focus and respond when prompted.

---

8. Imaging with Optical Coherence Tomography (OCT)

• Purpose: Provides high-resolution cross-sectional images of the optic nerve and retinal nerve fiber layer (RNFL) to detect thinning.
• Reference: Mwanza JC, Oakley JD, Budenz DL, et al. (2012). Spectral-domain OCT offers excellent diagnostic performance and can detect early nerve fiber loss.
• Process: You rest your chin on a support and stare at a target. The machine scans without touching your eye.
• What to Expect: Non-contact, painless scan lasting a few seconds per eye.

---

After the Exam: Interpreting Results and Next Steps

Once all tests are complete, your eye care professional will:

• Review IOP, corneal thickness, gonioscopy findings, optic nerve appearance, and imaging results.
• Compare your visual field test responses to normative databases to detect patterns consistent with glaucoma.
• Discuss whether you have normal-tension glaucoma, primary open-angle glaucoma, angle-closure glaucoma, or are simply a glaucoma suspect.
• Recommend treatment options if needed:
  • Prescription eye drops to lower IOP
  • Laser therapy (e.g., selective laser trabeculoplasty)
  • Surgery in more advanced cases

Even if your results are normal, regular follow-up exams (every 6–12 months) may be advised based on your risk profile.

---

What You Can Do Now

• If you’ve noticed vision changes or have risk factors, consider a free, online symptom check for glaucoma to help you decide whether to schedule a full exam.
• Maintain healthy habits: exercise regularly, eat a balanced diet, and manage chronic conditions like diabetes and hypertension.
• Wear protective eyewear during activities that could injure your eyes.

---

When to Speak to a Doctor

A glaucoma eye exam is a routine, painless way to preserve your vision. However, if you experience any of the following, contact your eye doctor or seek immediate medical attention:

• Sudden vision loss or severe eye pain
• Halos around lights with nausea or headache (possible acute angle-closure glaucoma)
• Red, inflamed eyes accompanied by sensitivity to light

Always speak to a doctor about any serious or life-threatening symptoms. Early detection and treatment of glaucoma can protect the vision you rely on every day.