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 60-year-old male judge with hypertension and diabetes describes a single episode of monocular transient visual loss OD. A dark curtain descended from superior to inferior OD, lasted 10 minutes and then spontaneously resolved. The patient was seen by an outside ophthalmologist and a diagnosis of “retinal migraine” was made. The next day the patient suffers two more episodes of similar visual loss and calls the ophthalmologist back and is given a referral for a two week appointment to neurology for “migraine”. That night the patient suffers a hemispheric stroke with hemiparesis and aphasia. A carotid study shows near occlusion of the right internal carotid artery.\nThe diagnosis of “retinal migraine” is one of exclusion. In elderly patients the diagnosis should be made with caution in the absence of headache history, prior attacks without residual or sequelae, and in patients who have vasculopathic risk factors. The International Headache Society (IHS) criteria for the diagnosis include: “≥ 2 attacks of “fully reversible” monocular visual loss with migraine headache”. The presumptive vasospasm mechanism for migraine headache and visual aura has fallen out of favor and spreading depression of cortical neuronal activity is a more plausible explanation for the visual symptoms in migraine. Unfortunately there is no diagnostic test for the migraine aura and a convincing history is required for the diagnosis. The role of the ophthalmologist is to exclude permanent visual loss after the event by performing formal visual field, documenting that there is no permanent residual loss, and ruling out alternative etiologies or eye markers for ischemic disease (e.g., central or branch retinal artery occlusion, Hollenhorst plaque). The most characteristic historical features for migraine are positive (e.g., scintillation or fortification scotoma) rather than negative (e.g., a black curtain) visual phenomenon; march and build up across the visual field in a nonvascular distribution, stereotyped quality with repeated events without permanent sequelae; and preferably the headache follows the aura after a few minutes duration. The most worrisome historical features for ischemia as the cause for amaurosis fugax include older aged, vasculopathic patient with first onset of an altitudinal (e.g., curtain over my vision) onset and disappearance, duration of minutes (1-10”), and seconds in onset. I would consider ordering a work up in transient monocular visual loss for patients with altitudinal history (e.g., curtain of visual loss), visible embolus, residual visual field defect, vasculopathic risk factors, and an ischemic time course. I would expedite the evaluation if the course was one of an increasing crescendo of events. On the other hand, I often defer work up for visual loss symptoms which have been present for years (e.g., hundreds of events with no residual loss) or have longer duration (e.g., 1-2 hours to days); are non-altitudinal events, the patient has no vasculopathic risk factors, or gives only a vague history of blurring. The clinician should also try to elicit a history suggestive of fluctuating rather than transient visual loss that might suggest the more common benign etiologies like ocular surface disorders or dry eyes. I will give these latter patients a pinhole to try during the events and if it alleviates the problem then it can be safely assumed to be ocular surface or refractive in nature. I also ask the patients to keep a diary of their events to establish some of the historical details above and I often give an empiric artificial tear trial.