Idiopathic unilateral disc edema. The big blind spot syndrome.

Unilateral edema of the optic disc without any evidence of increased intracranial pressure or optic nerve dysfunction is an uncommon problem. We describe two patients with "the big blind spot syndrome" who presented with unilateral disc edema and normal optic nerve function except for an enlarged blind spot. The course was self-limited in both patients. The presenting neuro-ophthalmologic signs and symptoms were similar to those of intracranial hypertension. It can be distinguished from other causes of a unilateral swollen disc by the lack of intracranial hypertension, normal optic nerve function, and the absence of marked venous engorgement or peripapillary hemorhages. Its early recognition may spare the patient unnecessary diagnostic procedures.