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 65-year-old woman with hypertension and diabetes presents with new awareness of blurred vision OD for two days. The visual acuity was 20/40 OD and 20/20 OS. No visual field is performed. The pupil examination showed a relative afferent pupillary defect (RAPD) OD. Ophthalmoscopy showed a normal optic nerve OD. The remainder of the eye exam was normal OS. A diagnosis of “posterior ischemic optic neuropathy” (PION) is made and the patient is instructed to return for a “next available” visual field test. The patient returns two months later and reports that “his vision is worse”. The vision is now 20/400 OD and 20/25 OS. There is a right RAPD. The Goldmann visual field showed a bitemporal hemianopic visual field loss with a superimposed central loss OD. There is now optic atrophy OD. A cranial MRI showed a pituitary adenoma compressing the optic nerve OD. A new eye doctor sees the patient and tells her that “If only you'd come to me sooner you would not be blind.”\nThe diagnosis of posterior ischemic optic neuropathy (PION) is one of exclusion. PION does occur and can be classified as arteritic (i.e., related to giant cell arteritis) or non-arteritic. The non-arteritic form is generally seen in the setting of perioperative or post-operative ischemic optic neuropathy after spine or cardiovascular surgery. Post-operative PION however has been seen after multiple surgical procedures.\nSadda et al. reported a retrospective chart review of 72 patients (98 eyes) with a clinical diagnosis of PION: perioperative (28 patients), arteritic (6 patients), and nonarteritic systemic vascular disease (38 patients). Among eyes with nonarteritic PION, 34% experienced improvement in vision, 28% remained stable, and 38% worsened.\nIt is my opinion that before the diagnosis of PION can be made two conditions must be excluded. First giant cell arteritis and second a compressive lesion producing a retrobulbar optic neuropathy. The key feature differentiating AION from PION is the presence of optic disc edema in the acute setting. Retrobulbar optic neuritis is typically a disorder of young patients and most commonly associated with multiple sclerosis. Retrobulbar optic neuritis however is rare in the elderly and the diagnosis should not be made without an imaging study. Compressive lesions can mimic an acute onset as seen in ischemic disease. In addition, corticosteroids a common treatment of retrobulbar optic neuritis can be disastrous in a patient harboring a fungal orbital apex lesion producing the retrobulbar optic neuropathy. Thus the diagnosis of retrobulbar “optic neuritis” should be made with extreme caution in the elderly. I generally recommend that a fluorescein angiogram be considered in elderly patients with suspected PION. The finding of choroidal perfusion deficit in the setting of PION is strongly suggestive of giant cell arteritis. Corticosteroids might be useful empirically for both arteritic and nonarteritic PION but an imaging study as mentioned above might be advisable prior to starting treatment.\nI would accept the diagnosis of PION of the clinical findings are consistent with an optic neuropathy (i.e., visual loss, RAPD, optic neuropathy related visual field), there is a clear etiology (i.e., post-surgical PION or giant cell arteritis), and optic atrophy develops over time. If there is no clear etiology for the PION, then a neuroimaging study is recommended (preferably cranial MRI with contrast and orbital fat suppressed views).