(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York
Subject
NAION; Disc Edema; Steroids
Description
Dr. Lee lectures medical students on incipient NAION.
Transcript
"So we're going to be talking about Incipient NAION which is Non-arthritic Anterior Ischemic Optic Neuropathy. Incipient means it hasn't happened yet, but it is going to happen. So as you know, the most common cause of an acute unilateral optic neuropathy with optic disc edema in an older vasculopathic patient is non-arthritic anterior ischemic optic neuropathy. It can have variable decreased acuity. You're going to have a relative afferent pupillary defect (RAPD). Normally, it's like an inferior altitudinal or some other nerve fiber layer defect. It's unilateral in the involved eye that's swollen, and the fellow eye usually has a small cup to disc ratio which is the structural disc at risk. That's typical garden variety NAION. However, sometimes when you're seeing this patient right here for acute unilateral loss of vision, swollen disc, RAPD - on the other side there happens to be swelling. That is usually incidental and asymptomatic. This we call incipient NAION. It's incipient because if you don't do anything a lot of these people are going to go ahead and go on to lose their vision, but they haven't yet. And so in this circumstance, normally I would do steroids. You obviously have to do a Sed Rate (ESR) and a CRP to make sure it's not Arthritic Anterior Ischemic Optic Neuropathy (A-AION). And we're going to do a temporal artery biopsy to make sure it's not giant cell arteritis. So if the biopsy is negative, the Sed rate and CRP are normal - you still might consider steroid here to treat that disc edema and make it go down. Even though steroids have never been proven in NAION, steroids do reduce the rate of the disc edema and the duration of the disc edema and so it is theoretically possible that incipient NAION would still respond to corticosteroid therapy. Even though the randomized trials that have been done on steroids and NAION have failed to show benefit. So, I still offer steroids to patients who have incipient NAION. We're going to admit this to the hospital because it's bilateral disc edema and that means you're going to do the usual suspects -an MRI and a lumbar puncture. If these are negative, we're still going to do the Sed Rate, CRP, the temporal artery biopsy and steroids but for a shorter period of time if the biopsy is negative to get the swelling down. Once the swelling goes down, if the vision returns to normal and no field defect occurs you could probably take credit for preventing the incipient NAION from becoming full-blown NAION."
