A 45-year-old woman is referred for Humphrey visual field testing for suspected normal-tension glaucoma. The report shows a MD of −4.2 dB, PSD of 5.8 dB, and a clustered inferior nasal step with GHT result 'outside normal limits.' The reliability indices show fixation losses of 3/18, false positives 8%, and false negatives 2%. What is the MOST appropriate interpretation?

• A The field is unreliable due to high false positives; repeat testing required
• B The nasal step alone without PSD elevation is not diagnostic
• C The field is reliable and shows early glaucomatous defect ✓
• D Fixation losses of 3/18 invalidate the test

Explanation

Reliability criteria for Humphrey perimetry: fixation losses <20%, false positives <15%, false negatives <33%. Here, fixation losses 3/18 (16.7% — borderline but acceptable), false positives 8%, false negatives 2% — all within acceptable limits, making the field reliable. A PSD of 5.8 dB is significantly elevated (normal <2 dB), GHT 'outside normal limits,' and an inferior nasal step are classic early glaucomatous findings. False positives of 8% are below the 15% threshold for unreliability.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.