Humphrey Visual Field Testing (Automated Static Perimetry)

Purpose

Automated static threshold perimetry — most commonly performed on the Humphrey Field Analyzer — quantifies visual sensitivity at many individual points across the visual field, producing a reproducible, quantitative map used to detect, characterize, and monitor visual field loss from glaucoma, neuro-ophthalmic disease, and other optic pathway disorders. It is the field-testing standard against which confrontation testing and other screening methods are compared.

Equipment

• A perimeter (e.g., Humphrey Field Analyzer)
• The patient's current, up-to-date refractive correction (a near-correction lens is used for standard test distances)
• An eye patch to occlude the untested eye
• A response button for the patient

Steps

1. Confirm the correct near-refractive lens is in the trial lens holder for the patient's age and correction, and position the patient with the tested eye centered and in focus.
2. Patch the untested eye.
3. Select the appropriate test strategy and pattern (e.g., 24-2 or 30-2 SITA Standard/Fast) based on the clinical question (glaucoma screening/monitoring versus a wider field for suspected neurological disease).
4. Instruct the patient to fixate steadily on the central target throughout and press the response button whenever they perceive a light stimulus, even if only dimly seen, without deliberately searching for stimuli with their eyes.
5. The machine presents light stimuli of varying intensity at pre-set locations, using an adaptive thresholding algorithm to estimate the sensitivity threshold at each point.
6. Monitor the patient during testing for fatigue, fixation loss, and false-response indicators (false positives, false negatives) tracked automatically by the machine.
7. At test completion, review the reliability indices (fixation losses, false positive/negative rates) before interpreting the sensitivity map, since an unreliable test cannot be meaningfully interpreted.

Normal vs. Abnormal Findings

• Normal: full, reproducible sensitivity across the tested field, corresponding to age-adjusted normative values, and reliability indices within acceptable limits.
• Glaucomatous defect: characteristic patterns including nasal step, arcuate (Bjerrum) scotoma, and paracentral defects, respecting the horizontal meridian due to retinal nerve fiber layer anatomy.
• Neuro-ophthalmic defect: patterns respecting the vertical meridian (homonymous hemianopia/quadrantanopia from retrochiasmal disease) or bitemporal patterns (chiasmal compression, e.g., pituitary lesion).
• Unreliable test: high fixation loss, false positive, or false negative rates, or a "clover-leaf" pattern from inattentive or inconsistent responses — such results should prompt repeat testing rather than clinical interpretation.

Common Mistakes

• Using outdated or incorrect refractive correction, artificially depressing sensitivity across the field (a lens rim or edge artifact can also cause a spurious peripheral defect).
• Failing to monitor and account for patient fatigue, particularly in longer test strategies or patients being tested for the first time.
• Over-interpreting a single field test without considering learning effect (first-time test unreliability that improves on repeat testing) or without comparing to prior fields to assess for a genuine trend versus test-retest variability.
• Ignoring poor reliability indices and interpreting an unreliable test as if it reflected genuine field loss.

OSCE Script

"I'm going to test your side vision one eye at a time using this machine. Please keep looking at the center light the whole time, and press the button whenever you see a flash of light anywhere in your vision, even if it's very faint — you don't need to look for it, just respond to what you notice out of the corner of your eye."

Then narrate for the examiner: "I'm performing automated static perimetry using a 24-2 SITA Standard strategy, and I'll check the reliability indices before interpreting the printout."

Clinical Pearls

• Always check reliability indices (fixation losses, false positives, false negatives) before interpreting a visual field printout — an unreliable test should not be used to make clinical decisions
• A learning effect is common on a patient's first one or two visual fields, with results typically improving and stabilizing on subsequent tests; a new patient's baseline should ideally not rely on a single field alone
• Glaucomatous field defects respect the horizontal meridian (nasal step, arcuate scotoma) due to retinal nerve fiber layer anatomy, while neuro-ophthalmic (retrochiasmal) defects respect the vertical meridian
• Deep learning-based analysis of serial visual fields has shown strong discrimination for detecting true glaucomatous progression compared to conventional statistical criteria (Anderson's criteria, Glaucoma Hemifield Test, pattern standard deviation-based analysis) in early studies, though this remains an emerging approach requiring further validation before routine adoption¹
• Non-standard testing conditions, such as yellow-tinted lens filters sometimes used for glare or comfort, can measurably alter standard automated perimetry indices, so testing should generally be performed under the standard conditions the normative database was built on²

Common Pitfalls

• Interpreting a field test with poor reliability indices as though it reflected true visual field loss
• Attributing a change between two fields to true progression without considering test-retest variability, learning effect, or a change in testing conditions (e.g., lens correction, filters)²
• Relying solely on emerging deep learning progression algorithms without corroborating conventional statistical criteria and the overall clinical picture¹
• Failing to select the appropriate test pattern (e.g., using a narrow glaucoma-focused 24-2 pattern when a wider field is needed to characterize suspected neurological disease)