Visual Field Testing

Confrontation fields — a rapid screen comparing the patient's field to the examiner's, one eye at a time, four quadrants. Flags gross defects for formal testing.

Automated static perimetry (Humphrey and similar) — stationary stimuli of varying brightness map threshold sensitivity at fixed points. Kinetic (Goldmann) perimetry instead moves a target inward until seen, drawing isopters — now a special-case tool.

Test patterns — 24-2 covers the central ~24° (the glaucoma workhorse); 10-2 packs points into the central 10° for macular disease and advanced glaucoma. FDT offers fast screening; SITA strategies cut Humphrey test time dramatically, which itself improves reliability.

The blind spot — 15° temporal to fixation; the Heijl-Krakau method flashes stimuli there to catch fixation losses (a fixating eye can't see them).

Perimetry happens before dilation, and the fellow eye wears a proper patch — no fingers, no pressure. Right eye first by convention.

The printout is only as good as the technician's setup. The reliability indices — fixation losses, false positives, false negatives — record how the test went; watch them during the run, not just after.

Instruction is half the test — "keep looking at the center; press when you see a light; many lights are deliberately too dim to see, so missing some is normal; blink normally between lights." Patients told this stay calm; patients not told it hunt for stimuli and fail fixation.

High false positives = trigger-happy = an impossibly good 'white-out' field: pause, re-instruct, restart if needed.

Fatigue is an artifact — use pauses (hold the response button), encourage, and split long orders across a break.

Setup checklist — correct near add in the trial holder for the bowl distance and age (uncorrected presbyopia depresses everything); lens close and centered (a decentered lens draws a fake ring scotoma at the rim); lids taped if ptosis shadows the superior field; pupil size recorded (miosis under ~3 mm depresses thresholds — note miotic drops).

The technician recognizes patterns to check plausibility and flag surprises; interpretation is the physician's.

Glaucoma follows the nerve-fiber bundles: arcuate scotomas and nasal steps that respect the HORIZONTAL midline.

Neurologic disease respects the VERTICAL midline: bitemporal hemianopia (both temporal halves) points to the chiasm — classically pituitary; homonymous hemianopia (same side in both eyes) points behind the chiasm — stroke and tumor territory.

Artifacts masquerading as disease — lens-rim ring, ptosis shadow superiorly, miosis or missing add depressing everything, trigger-happy white-outs, fatigue fade in the second eye.

Global indices — Mean Deviation (MD) summarizes overall depression versus age-normal; Pattern Standard Deviation highlights localized loss.

Amsler grid — the central 10° at near, one eye at a time with reading correction: the macular complement to perimetry and the standard home-monitoring tool.