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).
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.