A 55-year-old man with hypertension and diabetes presents with new awareness of blurred vision OD for two months. The visual acuity was 20/25 OD and 20/20 OS. Goldmann perimetry demonstrated an inferior altitudinal visual field loss OD. The pupil examination showed a relative afferent pupillary defect (RAPD) OD. Ophthalmoscopy showed a pale optic nerve OD. The eye exam was normal OS. A diagnosis of “optic atrophy” OD was made and the patient was instructed to return in 3 months for a repeat visual field. The patient returns in 3 months and the vision is now counting fingers OD. Magnetic resonance imaging of the head and orbit showed optic nerve sheath enhancement OD consistent with an optic nerve sheath meningioma.\nOptic atrophy is not a diagnosis. The clinician should document a cause for the optic atrophy and if no etiology is established a neuroimaging study and other evaluation should be performed. In a 55-year-old vasculopathic male the most likely etiology for a unilateral optic neuropathy with optic atrophy is non-arteritic anterior ischemic optic neuropathy (NA-AION). The “anterior” in NA-AION refers to optic disc edema and the absence of documented disc edema phase should prompt consideration for evaluation for alternative etiologies. In this case the patient experienced acute awareness of his visual loss OD rather than acute onset and the disc edema phase was not seen. Although serial visual field and follow up for a presumptive diagnosis of optic atrophy due to NA-AION is reasonable the clinical plan should be well documented in the chart, the patient should be informed of the possibility for a compressive or other etiology, and imaging and other evaluation should be pursued if the patient has progressive signs or symptoms (as in this case).\nLee et al. previously reported on the diagnostic yield for the evaluation of isolated and unexplained optic atrophy. This study was a retrospective review of all charts with the diagnosis of optic atrophy. Included patients were adults with isolated, but unexplained, optic atrophy and patients were excluded if they were children, had incomplete or inadequate documentation of the findings, had non-neurologically isolated optic atrophy (e.g., other localizing findings), or had a history (e.g., prior neuroimaging study showed a compressive lesion, prior ischemic optic neuropathy) or examination (e.g., central retinal artery occlusion) evidence for an etiology for the optic atrophy. A total of 1110 charts with the diagnosis of optic atrophy were reviewed from the two participating institutions (368 from the University of Cincinnati and 742 from the University of Iowa). Of these 1110 charts, 91 (8%) with isolated unexplained optic atrophy were included, and 1019 charts (92%) were excluded. Of the 91 cases included 18 (20%) had an underlying compressive lesion causing optic atrophy and 73 (80%) cases had no etiology for the optic atrophy on neuroimaging. Of the 18 patients with abnormal neuroimaging studies (e.g., meningioma, pituitary adenoma, or craniopharyngioma) 11 had bilateral and 7 had unilateral optic atrophy. Five of the 18 patients had progressive visual loss, 3 had hemianopic visual field loss, and 11 were younger than 50 years old. This study demonstrates that the risk of missing a compressive lesion in unexplained optic atrophy is high (20%) and that clinicians should not make the diagnosis of optic atrophy alone without an underlying proven or postulated mechanism.
A 25-year-old woman presents with chronic and unresolved loss of vision OD that occurred acutely two months prior to presentation. There is a right RAPD, a central scotoma OD on visual field testing, and a normal optic disc. Computed tomography (CT) scan of the head in the emergency room was normal. A diagnosis of chronic optic neuritis” is made.\nChronic “optic neuritis” is a real diagnosis but the clinician should be careful to insure that the patient has a confirmed diagnosis of multiple sclerosis and no alternative etiology for the optic neuropathy. Typical optic neuritis resolves (20/40 or better vision) in over 90% of cases and lack of improvement should be a big “red flag” that the diagnosis is incorrect. In my experience patients with chronic”“optic neuritis” due to demyelinating disease often have a systemic MS course that mirrors the course of their optic neuropathy (i.e., primary or secondary progressive rather than relapsing-remitting course). One should also be cautious of using the term “optic neuritis” when one truly means optic neuropathy. Misusing or mixing terms (e.g., papilledema) or creating neologisms (e.g., “ischemic optic neuritis”) also is potentially misleading to your colleagues. The bottom line is that typical optic neuritis usually gets better over time and patients with an atypical course (e.g., “chronic optic neuritis”) should have evaluation for alternative etiologies for their optic neuropathy including neuroimaging. There are potentially dangerous conditions that could mimic the presentation of acute painful optic neuropathy and suggest a diagnosis of demyelinating optic neuritis (e.g., pituitary apoplexy or ophthalmic artery aneurysm). In addition there are subsets of variants of demyelinating optic neuropathy that may not have as favorable a rate of recovery and therefore might suggest alternative diagnoses (e.g., neuromyelitis optica). Finally, some patients with the mitochondrial disorder, Leber hereditary optic neuropathy (bilateral acute visual loss with cecocentral scotomas in a young male) can be associated with MS like illness. Although rare, I would accept the diagnosis of “chronic optic neuritis” as a diagnosis of exclusion if a high quality MR scan of the head and orbit with gadolinium has excluded a compressive lesion, the patient has clear diagnosis of prior multiple sclerosis, and alternative MS mimics have been considered and adequately excluded. I typically will inform the treating neurologist of the findings and my concerns and if there is any history of transverse myelitis or if the optic neuropathy is bilateral then I would consider evaluation for neuromyelitis optica (NMO) including NMO antibody testing. I would also consider ordering the mitochondrial genetic testing for Leber hereditary optic neuropathy if the patient has bilateral central or cecocentral scotomas especially in a young man.