A 54-year-old man undergoes automated perimetry as part of glaucoma screening. The visual field shows a small paracentral scotoma located 10 degrees from fixation in the superior nasal quadrant, not respecting the horizontal midline. This finding corresponds to which pattern of retinal ganglion cell axon loss?
- A Nasal step
- B Paracentral scotoma (earliest defect) ✓
- C Arcuate scotoma
- D Temporal wedge
Correct answer: B. Paracentral scotoma (earliest defect)
Explanation
Paracentral scotomas located within 10-20 degrees of fixation are among the earliest reproducible visual field defects in primary open-angle glaucoma, resulting from focal loss of arcuate nerve fiber bundles. Arcuate scotomas are more advanced. Nasal steps are relative defects respecting the horizontal midline. Paracentral scotoma may be missed on standard screening thresholds and requires dedicated glaucoma testing.
Reference: The Glaucomas, 3rd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.