**Core Concept**
Primary narrow-angle glaucoma is a medical emergency characterized by an acute increase in intraocular pressure (IOP) due to a sudden blockage of the trabecular meshwork by the iris. This results in a rapid increase in IOP, leading to severe pain, redness, and vision loss. The condition is often associated with anatomical abnormalities such as a shallow anterior chamber.

**Why the Correct Answer is Right**
Option C is incorrect because glaucomatous cupping is a feature of chronic glaucoma, not acute primary narrow-angle glaucoma. In chronic glaucoma, the increased IOP causes damage to the optic nerve over a prolonged period, resulting in the formation of a cup in the optic disc. In contrast, acute primary narrow-angle glaucoma is characterized by a sudden and severe increase in IOP, which does not allow sufficient time for glaucomatous cupping to develop.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the IOP in acute primary narrow-angle glaucoma typically ranges from 40-90 mmHg, not 940-70 mmHg. The extremely high IOP value in this option is not a characteristic of this condition.

**Option B:** This option is correct and describes common features of acute primary narrow-angle glaucoma, including eye redness, pain, and tenderness.

**Option D:** This option is correct and describes a common feature of primary narrow-angle glaucoma, where the fellow eye often has a shallow anterior chamber.

**Clinical Pearl / High-Yield Fact**
In acute primary narrow-angle glaucoma, the IOP can increase rapidly, leading to optic nerve damage and potentially permanent vision loss. Prompt recognition and treatment of this condition are essential to prevent long-term complications.

**Correct Answer:**
✓ Correct Answer: C. Disc shows glaucomatous cupping