Retrobulbar neuritis is an inflammation affecting the optic nerve behind the eyeball without ophthalmoscopic manifestations in the fundus. It is characterized by a sudden loss of vision occurring over a period of from one to eight days. The condition may be acute or chronic, the latter type usually being referred to as toxic amblyopia. Acute retrobulbar neuritis is usually unilateral, whereas toxic amblyopia is generally bilateral.
Patients with retrobulbar neuritis usually have a history of failing vision which has progressed rapidly and which may proceed to almost complete blindness. Although this blindness may be permanent, it is usually restored with treatment. Occasionally there is some pain on movement of the eyeball.
Examination will ordinarily reveal normal fundi, although there may be some hyperemia of the disk. Duke-Elder1 states, “In the majority of cases the fundus appears normal and the condition may be defined as a disease in which neither the examiner nor the patient sees anything.” The pupillary reflex is usually of significance and, according to Parsons,2 a lack of sustained constriction of the pupil to light, if it can be placed beyond dispute, is of the greatest diagnostic significance. Visual fields are an important part of the examination. A central scotoma is the usual finding early in the disease, although if the disease has progressed far enough the loss of vision may be so great that only a small island of vision remains. A cecocentral scotoma may be present and, if bilateral, is almost diagnostic of toxic amblyopia.
Etiologic. . .