Chapter 2 Is It a Neuro-Ophthalmic Problem? (If Not, What Else Could It Be?)

Abstract

Publisher Summary This chapter clinically evaluates optic neuropathy. It discusses ocular media abnormalities; abnormalities of the macula and outer retina; retinovascular occlusion and retinal detachment; and retinal degenerations. It emphasizes the historical and clinical features that help differentiate an optic neuropathy from the more common ocular causes of visual loss. Optic neuropathies account for most instances of neurogenic visual loss. The classic features of an optic neuropathy are as follows: (1.) central visual loss, (2.) clear view through to the optic nerve, (3.) relative afferent pupillary defect, and (4.) swollen or pale appearing optic nerve. If all these features are met, there is little question as to localization of the lesion. Of course, it is not always so clear-cut. Some optic neuropathies may spare central visual acuity. Glaucoma is a prime example. Furthermore, in up to 50% of patients with nonarteritic anterior ischemic optic neuropathy, for example, visual acuity is good despite altitudinal visual field loss. In other acute optic neuropathies, such as the majority of cases of retrobulbar idiopathic optic neuritis, the optic nerve appears normal for at least 4 to 6 weeks before optic nerve head pallor ensues. However, in the last two examples, the presence of other features, especially a relative afferent pupillary defect, facilitates recognition of the optic nerve as the locus of pathology. A more difficult situation occurs when the optic neuropathy is bilateral and symmetrical, and therefore a relative afferent pupillary defect may not be present.