Decreased visual acuity from optic disc drusen.

Although visual field defects occur commonly from optic disc drusen, reduction in visual acuity is rare. We describe four patients with reduced visual acuity and one with visual field constriction to the point of legal blindness that resulted from optic disc drusen. The acute episodic and stepwise nature of visual loss in some of the cases in our series suggests a vascular mechanism. Reduced visual acuity from drusen remains a diagnosis of exclusion. It should be considered, however, when visual loss has been acute and nonprogressive or stepwise in a nerve fiber bundle distribution and when visual acuity is not reduced until visual field constriction is severe.