Diagnosis and Treatment of Arteritic Anterior Ischemic Optic Neuropathy

- CE credits 1.5 hours
- COPE code 64795-NO / 118207
- Available until Sep 20, 2022

Introduction

Learning Objectives

To describe the presentation, causes, and work-up of anterior ischemic optic neuropathy.
To review giant cell arteritis, its ophthalmic manifestations and management.

Case

A 76 year-old woman presented to the Emergency Department with sudden onset vision loss in the right eye. She has been otherwise well, her only other complaint is recent onset of a left-sided headache a few days preceding her vision changes. Her medical history is significant for hypertension and dyslipidemia, for which she takes amlodipine, hydrochlorothiazide and atorvastatin.

Examination reveals a well-looking individual in no distress, afebrile with blood pressure 142/86 and pulse of 78. Her best-corrected vision in the right eye is 20/30, hand motion in the left eye. There is a brisk left relative afferent pupillary defect. Slit lamp examination of the anterior segment shows only mild nuclear sclerosis of the lens. Fundoscopy is shown below.

Quick Question

What is the most important investigation to order immediately in order to make a diagnosis?

Carotid Dopplers

Carotid Dopplers are indicated where there is suspicion of embolic diseases, such as in amaurosis fugax or central retinal artery occlusion, as both are known to be associated with embolic carotid artery stenosis. In our patient, there is swelling of the left optic disc, which if associated with ischemia, would imply non-perfusion at the level of the posterior ciliary arterial system - which is not typically associated with an embolic pathogenesis. With ischemic optic neuropathy, hypoperfusion is caused by thrombosis (NAAION) or inflammation (AAION) of the short posterior ciliary arteries supplying the optic nerve head.
Fluorescein angiography

While fluorescein angiography can be a useful test to assess the integrity of the choroidal circulation, and impaired choroidal perfusion strongly indicates an arteritic cause of ischemic optic neuropathy, it is neither sensitive nor specific. This test is often not readily available, and a delay in diagnosis is unacceptable in this case.
-2 Visual field test

A visual field test is often performed as part of a baseline assessment, but is not helpful in making the diagnosis of arteritic versus nonarteritic ischemic optic neuropathy. Furthermore, a patient with hand motion vision will be unlikely to reliably perform automated perimetry.
Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)

CORRECT

An elderly patient with sudden visual loss with a headache must be assumed to have an arteritic cause for a CRAO or anterior ischemic optic neuropathy until proven otherwise In the setting of disc swelling, the role of the evaluating clinician is to distinguish between the more common nonarteritic form and the potentially devastating arteritic form related to giant cell arteritis. Serum inflammatory markers, most commonly being an ESR and CRP, can be rapidly obtained and have very high sensitivity and specificity. Most clinicians would also include a complete blood count as thrombocytosis and anemia are common findings in GCA.
Non-contrast CT scan of the head

Monocular vision loss localizes to the anterior visual pathway. A non-contrast CT head is of minimal value in this scenario and is primarily used in the emergency department in order to rule out acute intracranial hemorrhage.

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