A 65-year-old man with POAG has a cup-to-disc ratio of 0.8 with a healthy neuroretinal rim inferiorly. Visual field shows a nasal step corresponding to the superior arcuate fibre bundle. Which pattern of retinal nerve fibre layer loss is most characteristic of this finding?
- A Diffuse loss of the entire RNFL
- B Focal wedge-shaped defect in the inferior RNFL
- C Focal wedge-shaped defect in the superior RNFL ✓
- D Papillomacular bundle loss
Correct answer: C. Focal wedge-shaped defect in the superior RNFL
Explanation
Glaucomatous damage typically produces focal, wedge-shaped RNFL defects corresponding to the area of rim loss. Since the superior arcuate fibres are affected (nasal step), the defect is in the superior RNFL. Diffuse loss is less specific and seen in myopic or senile changes. The healthy inferior rim means inferior RNFL is spared. Papillomacular loss suggests a retinal or neurological process.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.