Idiopathic intracranial hypertension (IIH) is considered when evaluating a young patient with symptoms such as headache, transient visual obscuration or finding of palliedema. Lumbar puncture (LP) with opening pressure recording and cerebrospinal fluid (CSF) examination are required in patients with suspected IIH. Patients with IIH can have large variations in intracranial pressure (ICP), but rarely a single measurement of ICP is normal. Pathological conditions that resemble IIH clinically include cerebral mass lesions, hypertensive encephalopathy, hydrocephalus, and dural sinus thrombosis. Chronic forms of meningitis such as cryptococcal meningitis can resemble IIH initially because of headache and papilledema. Changes in visual acuity or visual-evoked potentials are signs of end-stage IIH-related optic nerve injury. Hospitalization is required when rapid visual loss or serious complications of IIH are suspected. Consultation with a neurologist, ophthalmologist, and neurosurgeon is indicated according to the severity of symptoms and the current treatment.

Diplopia, visual loss, and pupillary asymmetry are important presentations of neuroophthalmologic emergencies. When evaluating a patient with diplopia, the most important initial step is to determine whether the diplopia is monocular or binocular. Binocular diplopia resolves when either eye is covered. Monocular diplopia usually results from ophthalmologic causes or refractive errors. Binocular diplopia results from ocular misalignment. Diplopia is most pronounced when looking in the direction of the limited extraocular movement regardless of cause. Neuro-ophthalmologic visual loss is divided into prechiasmal, chiasmal, or postchiasmal etiologies. Monocular visual loss indicates a lesion anterior to the chiasm. Pupils are evaluated for reactivity and size in light and dark environments. Anisocoria is defined as unequal pupil size. A significant percent (approximately 20%) of the population has minimal anisocoria without pathology, termed physiological or simple anisocoria. Only physiological anisocoria or Horner's syndrome produce anisocoria with normally reactive pupils.