A 62-year-old man with a family history of glaucoma presents for routine eye examination. Fundoscopy reveals the finding marked **A** in the diagram. Gonioscopy confirms an open iridocorneal angle, and automated perimetry shows a paracentral scotoma in the superior field. Intraocular pressure is 18 mmHg in both eyes. Which of the following best describes the diagnostic significance of the finding marked **A** in establishing the diagnosis of primary open-angle glaucoma?
A. It represents acquired loss of retinal ganglion cells and is a characteristic optic nerve head sign that, combined with open angle and visual field defect, supports the diagnosis of POAG
B. It is a sign of acute angle closure and requires immediate laser peripheral iridotomy
C. It indicates elevated intraocular pressure and is the most important diagnostic criterion for POAG
D. It is pathognomonic for POAG and alone is sufficient for diagnosis regardless of visual field status
Explanation
Why option 1 is correct
The finding marked A (enlarged cup with cup-to-disc ratio > 0.7) represents acquired loss of retinal ganglion cells and their axons, a hallmark of primary open-angle glaucoma. According to AAO BCSC Section 10, POAG diagnosis requires the triad of: (1) open iridocorneal angle on gonioscopy, (2) characteristic optic nerve head changes (including cup-to-disc ratio > 0.6, focal notching, and disc asymmetry), and (3) corresponding visual field loss. The patient in this vignette has all three components—open angle, characteristic optic disc cupping (marked A), and paracentral scotoma—confirming POAG. Importantly, elevated IOP is NOT required for diagnosis; normal-tension glaucoma exists.
Why each distractor is wrong
Option 1: While the finding marked A is characteristic of POAG, it is NOT pathognomonic and is NOT sufficient alone. The diagnosis requires the complete triad; optic disc cupping alone without open angle confirmation and visual field defect cannot establish POAG diagnosis.
Option 3: Although elevated IOP is the single most important modifiable risk factor for POAG, it is NOT required for diagnosis. This patient has normal IOP (18 mmHg) yet has POAG. IOP is a risk factor, not a diagnostic criterion.
Option 4: The finding marked A (optic disc cupping) is a sign of chronic progressive optic neuropathy in POAG, not acute angle closure. Acute angle closure presents with a shallow anterior chamber, mid-dilated pupil, and corneal edema—not disc cupping.
High-YieldNEET PG
POAG diagnosis = open angle + optic nerve head changes (CDR > 0.6, notching, asymmetry) + visual field loss; elevated IOP is NOT required.
AAO BCSC Section 10: Glaucoma (2024)
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