Perimetry, or visual field testing, is a diagnostic procedure used to assess the extent and functionality of a person’s visual field, including peripheral (side) and central vision. This test helps detect vision loss caused by eye conditions such as glaucoma, retinal diseases, and neurological disorders.
Visual field testing is crucial for identifying blind spots (scotomas) or other abnormalities in a person’s field of vision. These defects often develop unnoticed because the brain can compensate for gaps in sight. Perimetry is especially valuable for detecting early-stage conditions like glaucoma, where peripheral vision loss might precede more noticeable symptoms. Regular testing can track disease progression and monitor the effectiveness of treatments.
Static Automated Perimetry: Involves detecting stationary light stimuli at varying intensities in a bowl-like instrument.
Kinetic Perimetry: Uses moving light stimuli to map the boundaries of the visual field.
Confrontation Testing: A manual method where the practitioner uses hand-held objects to test peripheral vision.
Amsler Grid Testing: Assesses central vision by asking patients to focus on a grid and report distortions.
These methods vary in complexity and application but are essential tools in modern optometry practices.
Perimetry or visual field testing is recommended for individuals at risk of:
- Glaucoma: A leading cause of vision loss, detectable through characteristic patterns of peripheral vision loss.
- Neurological conditions: Such as strokes or brain tumours, which may affect visual pathways.
- Retinal diseases: Like diabetic retinopathy or retinitis pigmentosa.
- Driver’s license requirements: In Australia, visual field testing may be necessary for maintaining a license.
While vision loss can often be subtle, certain signs warrant testing:
- Unexplained difficulty seeing objects in the periphery.
- Frequent bumping into objects or tripping.
- Difficulty navigating stairs or driving.
- Persistent headaches or eye strain, which might indicate optic nerve issues.
- Sudden changes in vision, including dark spots or tunnel vision.
The test involves sitting in front of a machine that flashes light stimuli while covering one eye. The patient presses a button when they detect the stimuli. Results are mapped to show areas of vision loss, providing critical information for diagnosis and treatment planning.
Perimetry is non-invasive, reliable, and widely available in Australian optometry clinics, including Kellyville Optical. If you suspect visual field changes, scheduling a perimetry test with your optometrist could protect your long-term vision health.
