On spectral-domain OCT of the peripapillary retinal nerve fibre layer in a healthy adult eye, which quadrant is normally the thickest?
- A Temporal
- B Nasal
- C Superior ✓
- D Inferior
Correct answer: C. Superior
Explanation
In the normal eye, the superior quadrant of the circumpapillary retinal nerve fibre layer is the thickest, followed closely by the inferior, then nasal, with the temporal quadrant being the thinnest. This distribution corresponds to the anatomy of the arcuate axonal bundles entering the disc. Diffuse thinning confined to the temporal quadrant alone should raise suspicion of a compressive or hereditary optic neuropathy rather than glaucoma. Loss of the superior-inferior asymmetry is an important glaucoma sign.
Reference: Kanski's Clinical Ophthalmology, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.