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I compared six subjects with pseudotumor cerebri and unilateral or highly asymmetric papilledema with 20 such patients with bilateral papilledema. Patients with unilateral papilledema were significantly older than those with bilateral papilledema, but there were no significant differences between the two groups in disease duration, elevation of intracranial pressure, visual fields and acuity, and presence of headaches or transient visual obscurations. I hypothesize that, in patients with unilateral papilledema, one optic nerve is protected from pressure effects by optic nerve sheath anomalies or lamina cribrosa changes due to increased collagen and decreased elasticity with aging.

Fifty-seven percent of 104 consecutive patients with retinal or neural visual loss reported spontaneous visual phenomena (SVP). Elementary SVP occurred more commonly (51% of patients) than complex SVP (21%). SVP occur with lesions of any portion of the visual pathways. Unlike irritative hallucinations, they do not aid in localization of the lesion. SVP occur significantly more frequently with visual acuity of 20/50 or less in both eyes. These purely visual hallucinations are unlikely to herald psychiatric disease and may be release phenomena stemming from loss of inhibitory visual input.