On Humphrey visual field testing, a patient with suspected normal-tension glaucoma shows a dense paracentral scotoma respecting the horizontal meridian in the superior field. Which parameter BEST indicates disease severity in this case?

• A Pattern standard deviation (PSD) ✓
• B Mean deviation (MD)
• C Visual field index (VFI)
• D Foveal sensitivity

Explanation

Pattern standard deviation (PSD) measures the variability of the sensitivity map from the expected pattern and is most sensitive for detecting focal, localized defects such as paracentral scotomas. Mean deviation reflects the overall average deviation from normal and is most affected by diffuse loss. VFI is a global percentage measure more useful for tracking progression. A focal superior paracentral defect in normal-tension glaucoma characteristically respects the horizontal raphe and is best captured by PSD.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.