**Core Concept**
Papilledema refers to the swelling of the optic disc due to increased intracranial pressure (ICP). It results from the accumulation of cerebrospinal fluid (CSF) or blood within the cranial vault, leading to compression of the optic nerve and subsequent optic disc swelling.

**Why the Correct Answer is Right**
Papilledema is characterized by the presence of flame-shaped hemorrhages, cotton-wool spots, and hard exudates on the surface of the optic disc. The increased ICP can also lead to the development of retinal vein engorgement and retinal ischemia. The optic disc may become elevated and may have a blurred or irregular margin. The symptoms of papilledema may include visual disturbances such as blurred vision, loss of peripheral vision, and transient visual obscurations.

**Why Each Wrong Option is Incorrect**
**Option A:** This statement is true about papilledema. It is a common sign of increased intracranial pressure, which can be caused by various conditions such as brain tumors, hydrocephalus, and hemorrhage.
**Option B:** This statement is also true about papilledema. The optic disc swelling is often accompanied by signs of optic nerve damage, including visual field defects and loss of color vision.
**Option C:** This statement is incorrect about papilledema. Papilledema is not a sign of glaucoma, which is a separate condition characterized by increased intraocular pressure.

**Clinical Pearl / High-Yield Fact**
It's essential to differentiate papilledema from other causes of optic disc swelling, such as optic neuritis or glaucoma. A thorough medical history, physical examination, and imaging studies, including computed tomography (CT) or magnetic resonance imaging (MRI), can help diagnose the underlying cause of the optic disc swelling.

**Correct Answer: C. Papilledema is not a sign of glaucoma.**