Visual Field Testing Flashcards

A patient with end-stage glaucoma (mean deviation -24 dB) shows a false-negative rate of 52% on Humphrey SITA Standard testing. The technician flags the test as unreliable and wants to repeat it immediately. What is the most accurate interpretation of this finding?

Answer: In advanced glaucomatous disease, elevated false-negative rates commonly reflect disease severity rather than unreliable performance

In advanced glaucoma, false-negative rates are frequently elevated even in cooperative, attentive patients. Severely damaged retinal areas may fail to respond when a stimulus is presented at a previously seen threshold location — not because the patient is inattentive, but because those areas are too damaged to respond consistently. Repeating the test based solely on this index in end-stage disease is unnecessary; clinical judgment alongside structural data is required.

A Humphrey 24-2 SITA Standard field on a 70-year-old patient with 2+ nuclear sclerotic cataracts shows diffuse depression on the total deviation plot, but the pattern deviation plot reveals a focal inferior arcuate defect. Which statement best explains this discrepancy?

Answer: Pattern deviation corrects for generalized depression, isolating focal defects such as a glaucomatous arcuate scotoma superimposed on cataract-related diffuse loss

The pattern deviation plot mathematically removes the overall height shift of the hill of vision — correcting for diffuse depression caused by media opacities, miosis, or refractive error. This makes focal, localized defects (like glaucomatous nerve fiber bundle loss) visible even when a cataract is causing a simultaneous global reduction. The total deviation plot cannot distinguish a focal glaucomatous defect from a cataract-driven diffuse depression on its own.

A Humphrey visual field printout shows: mean deviation −1.6 dB (no probability flag), pattern standard deviation flagged at p<2%, and the Glaucoma Hemifield Test reading 'Outside Normal Limits.' Which interpretation is most clinically accurate?

Answer: The flagged PSD and abnormal GHT together suggest early focal glaucomatous damage in the absence of significant overall depression

Early glaucoma often damages discrete nerve fiber bundles, producing a localized scotoma (reflected by an elevated PSD) while leaving the global field nearly intact (near-normal MD). In this scenario, PSD is actually more sensitive than MD for detecting early focal loss. A GHT of 'Outside Normal Limits' combined with a flagged PSD in the setting of a near-normal MD is a classic early-glaucoma presentation and warrants structural correlation and close follow-up.

A patient's visual field reveals a central scotoma in the right eye combined with a superior temporal defect in the left eye. This specific pattern — known as a junctional scotoma — most precisely localizes the lesion to which anatomical site?

Answer: The junction of the right optic nerve and the anterior optic chiasm

A junctional (or 'junction') scotoma occurs when a lesion affects the junction of the optic nerve and chiasm on one side. The ipsilateral eye develops a central scotoma from direct optic nerve involvement. The contralateral superior temporal defect arises because nasal fibers from the contralateral eye loop anteriorly into the ipsilateral optic nerve (Wilbrand's knee) before decussating — damaging them along with the ipsilateral nerve. This is a critical neuro-ophthalmic localizing pattern.

During kinetic Goldmann perimetry on a patient with severe concentric field constriction, a technician is mapping the remaining central island using a V4e isopter and then attempts the I4e target. The patient fails to respond to I4e at any location. What is the most appropriate next action?

Answer: Increase the stimulus size to II4e and systematically remap the central area before concluding

In Goldmann kinetic perimetry, the Roman numeral designates stimulus size (I = 0.25 mm², II = 1 mm², III = 4 mm², etc.). When a patient fails to detect a given target, the correct progression is to increase stimulus size (move to a higher Roman numeral), not to decrease it. Attempting II4e is the appropriate escalation before concluding that no further field can be mapped. Documenting no measurable field without trying larger stimuli would be a premature and clinically inaccurate conclusion.

A technician performs a Humphrey 24-2 SITA Standard field on a cooperative patient. The reliability indices show: fixation losses 0/12, false positives 22%, false negatives 4%. The field printout displays several scattered, seemingly deep defects. Which statement best describes how the high false-positive rate affects interpretation?

Answer: High false positives indicate trigger-happy responses, causing artificially improved (more sensitive) threshold values that may mask true defects

A high false-positive rate means the patient is pressing the response button even when no stimulus is presented (trigger-happy behavior). This artificially lowers the threshold estimates — making the perimeter 'think' the patient can see stimuli at lower intensities than they truly can. The result is artifactually better-than-true thresholds, which can mask real scotomas. Paradoxically, deep-looking defects on a high false-positive test should be regarded with suspicion as a 'clover-leaf' artifact pattern, where fatigue later in the test makes the early (artificially low) thresholds stand out.