Diagnostic Testing for Glaucoma
Glaucoma cannot be diagnosed based on symptoms alone. In fact, most patients with early glaucoma feel completely normal. That is why comprehensive eye testing is essential.
Your eye doctor uses several specialized tests to detect early optic nerve damage and measure risk.
Why Testing Matters
Glaucoma often causes no pain and no noticeable vision changes in its early stages. By the time symptoms appear, permanent nerve damage may already have occurred.
Because vision lost to glaucoma cannot currently be restored, early diagnosis is critical.
The Key Tests Used to Diagnose Glaucoma
A glaucoma evaluation typically includes multiple components. No single test alone confirms the diagnosis.
Tonometry (Eye Pressure Measurement)
Tonometry measures intraocular pressure (IOP) — the pressure inside the eye.
Elevated pressure is one of the strongest risk factors for glaucoma. However, it’s important to know:
- Some people develop glaucoma with normal pressure
- Some people have high pressure but never develop optic nerve damage
This is why pressure is only one piece of the puzzle.
Optic Nerve Examination
Your doctor will carefully examine the optic nerve at the back of the eye using specialized lenses.
They look for:
- Thinning of nerve fibers
- Changes in the optic disc
- Asymmetry between eyes
The optic nerve’s appearance often reveals early signs of damage before vision changes are noticeable.
Optical Coherence Tomography (OCT)
OCT imaging creates high-resolution cross-sectional images of the optic nerve and retinal nerve fiber layer.
This painless scan can:
- Detect microscopic nerve fiber thinning
- Track progression over time
- Identify damage before vision loss is obvious
OCT has become one of the most valuable tools in modern glaucoma management.
Visual Field Testing
Visual field testing measures your peripheral vision.
During the test, you press a button when you see small flashes of light. The results map areas where sensitivity may be reduced.
Because glaucoma typically affects side vision first, visual field testing helps detect and monitor functional vision loss.
Gonioscopy
Gonioscopy allows your doctor to examine the drainage angle — where fluid exits the eye.
This helps determine:
- Whether the angle is open or closed
- The type of glaucoma present
- Whether angle-closure risk exists
What Happens After Diagnosis?
If glaucoma is diagnosed, your doctor will recommend a management plan. This may include:
- Prescription eye drops
- Laser treatment
- Surgical procedures
- Regular monitoring visits
Early-stage glaucoma is often managed successfully when detected in time.