Papilledema: Swollen Optic Nerve 

Papilledema or papilloedema is the swelling of the optic disc or the part of the optic nerve located inside the eye. It is caused by intracranial hypertension (IH) or increased pressure within and around the brain.
Papilledema can develop within hours or weeks, depending on the underlying cause. It is usually bilateral and affects both eyes.
In rare cases, it has a unilateral presentation and affects one eye.
Papilledema or optic nerve swelling indicates the presence of a serious and often life-threatening condition.
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