Okay, let's tackle this question. The patient is 75 and has worsening vision, with a sluggish pupillary reflex and normal intraocular pressure. The optic disc has a large, deep cup and paracentral scotomas. Hmm, what are the possibilities here?

First, I need to think about the main causes of optic disc cupping and visual field defects. Glaucoma is a big one, especially open-angle glaucoma. But wait, the intraocular pressure is normal here. So maybe normal-tension glaucoma? That's a type where IOP is within the normal range but there's still optic nerve damage. Classic signs include cupping of the optic disc and visual field loss like paracentral scotomas.

Wait, the pupillary reflex is sluggish. In glaucoma, especially if there's optic nerve damage, the afferent pupillary defect (APD) might be present. But the question says the pupillary reflex is sluggish, not an afferent defect. Or maybe the damage is in the optic nerve itself. Let me think about other causes. Ischemic optic neuropathy? That can cause sudden vision loss and optic disc swelling initially, but the cupping here is large and deep. That's more chronic. Maybe arteriosclerosis or diabetes contributing to optic nerve damage?

Another possibility is age-related macular degeneration, but that affects central vision more and the pupillary reflex would be intact. Diabetic retinopathy? Usually has other signs like microaneurysms or hemorrhages. The cupping points more towards optic nerve pathology rather than retinal.

So, normal-tension glaucoma fits here. The key features are normal IOP, optic disc cupping, and paracentral scotomas. The sluggish pupillary reflex could be due to optic nerve dysfunction. Other options like open-angle glaucoma with high IOP are ruled out by normal IOP. Ischemic optic neuropathy might cause sudden loss but not the chronic cupping. So the answer is normal-tension glaucoma.

**Core Concept**
This question assesses the differential diagnosis of optic nerve damage with normal intraocular pressure (IOP). Key features include optic disc cupping, paracentral scotomas, and a sluggish pupillary reflex, pointing to **normal-tension glaucoma (NTG)** as the most likely cause. NTG is characterized by progressive optic neuropathy with normal IOP, often linked to vascular dysregulation or mechanical factors.

**Why the Correct Answer is Right**
Normal-tension glaucoma (NTG) involves optic nerve damage despite IOP within the normal range. The large, deep optic cup reflects atrophy of retinal ganglion cells and their axons. Paracentral scotomas are classic early visual field defects in NTG. A sluggish pupillary reflex may arise from impaired afferent input via the damaged optic nerve. Pathogenesis includes reduced ocular blood flow, vascular dysregulation, or biomechanical stress on the lamina cribrosa.

**Why Each Wrong Option is Incorrect**
**Option A:** Acute angle-closure glaucoma is ruled out by normal IOP and absence of ocular pain or corneal edema.
**Option B:** Ischemic optic neuropathy (ION) typically presents with sudden vision loss and a swollen optic disc (not cup

✓ Correct Answer: B. Normal Tension Glaucoma