A patient with primary open-angle glaucoma is being monitored with serial OCT retinal nerve fiber layer (RNFL) analysis. Which quadrant of the RNFL is typically the thickest in a normal eye?
- A Superior
- B Nasal
- C Inferior ✓
- D Temporal
Correct answer: C. Inferior
Explanation
In a normal eye, the inferior RNFL is the thickest quadrant, followed by superior, nasal, and temporal (the ISNT rule: Inferior > Superior > Nasal > Temporal). This is because the inferior arcuate nerve fiber bundle contains fibers serving the superior visual field and is anatomically thicker. Violation of the ISNT rule suggests glaucomatous damage.
Reference: Ophthalmology, AAO BCSC Section 10: Glaucoma, 2023-2024 ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.