Incorrect

Incorrect

Incorrect

Correct! The defect in the right eye has a substantial border aligned to the horizontal meridian in the nasal field. That feature marks it as a “nerve fiber bundle defect” that involves the upper arcuate bundles made up of retinal ganglion cell axons that converge upon the upper pole of the optic disc. This arcuate bundle can be damaged in many conditions, including optic nerve compression, inflammation, ischemia, trauma, congenital dysplasia, and retinal artery or vein occlusion. It is typically spared by hereditary (Leber, OPA 1), metabolic (nutritional and vitamin deficiency, alcoholism), and toxic (ethambutol and others) conditions, which usually damage the maculopapillar bundles to create central or centrocecal scotomas in both eyes. The swelling of the right optic nerve and the arcuate nerve fiber bundle visual field defects suggest five choices: 1) inflammation (“papillitis,” “optic neuritis”); 2) an orbital tumor; 3) an intracranial tumor entering the optic canal; 4) cancerous infiltration of the optic nerve; 5) optic nerve ischemia. Inflammation is a distinct possibility. So are tumors compressing the optic nerve in the orbit if they involve the nerve near the eye or the optic canal. So are intracranial tumors if they have entered the optic canal, a phenomenon especially common with sphenoid meningiomas. However, two features of this case favor a diagnosis of ischemic optic neuropathy: the sudden onset of vision loss and her medication list suggesting an arteriosclerotic risk profile. If she had a symptom complex to suggest polymyalgia rheumatica or cranial arteritis, you would have to consider the diagnosis of “arteritic ischemic optic neuropathy” and order a blood sedimentation rate and C-reactive protein (“acute phase reactants”), place the patient on prophylactic corticosteroid, and consider performing a temporal artery ultrasound looking for the characteristic “halo sign” of arteritis. However, even if the ultrasound is negative, you would likely move ahead with performing a temporal artery biopsy if the acute phase reactants are elevated or the patient has systemic symptoms of an arteritis. Otherwise—and most likely—she has non-arteritic ischemic optic neuropathy (NAION), a bland infarct in the optic disc caused by hypoperfusion. You would be more certain of that diagnosis in follow-up. If visual function improves, you would favor a diagnosis of papillitis.

If visual function worsens, worry about inflammation, a compressive tumor, or cancer infiltrating the optic nerve. If visual function remains unchanged, your presumptive diagnosis of NAION was probably correct. There are two reasons to make a diagnosis of NAION. First, it suggests that the patient has “small vessel” arterial disease, which may require prophylactic treatment. Second, there is a concern for overtreated systemic hypertension that results in low blood pressure and optic disc hypoperfusion especially during the early morning hours, which could also precipitate NAION in the unaffected eye. Monitoring of blood pressure to rule out nocturnal hypotension might reduce the chance that the second eye would be affected, a visually devastating occurrence. By the way, you should be asking whether orbit and brain imaging is indicated here. Strictly speaking, no, but the truth is that it will often be done in order to rule out those other choices without having to wait for the clinical course to establish visual stability.