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Nonarteritic Anterior Ischemic Optic Neuropathy

Nonarteritic Anterior Ischemic Optic Neuropathy

A 43-year-old white man presented to the emergency department with dyspnea, abdominal bloating, fever with chills, night sweats, decreased oral intake, and myalgia of 1 week's duration. He was found to have heart failure caused by systolic dysfunction. Viral myocarditis was the presumptive diagnosis after investigation for other causes.

Sepsis subsequently developed, followed by septic shock, acute renal failure, and respiratory failure. The patient was intubated and ventilated; he required multiple vasopressors to maintain blood pressure and continuous renal replacement therapy. Although the unifying diagnosis was a viral syndrome, no definite source was identified. He was eventually weaned from the ventilator, and his renal function recovered. During the recovery phase, he experienced sudden, painless loss of vision.

He had no light perception in the right eye and 20/25 vision in the left eye. The right pupil was unreactive to light, with a positive afferent defect; the left pupil was reactive. Visual field was completely obscured on the right; there was a minimal superior altitudinal defect on the left. Dilated funduscopic examination of the right eye showed a pale, resolving, edematous disc without hemorrhages or macular disturbance, such as a star formation. The left optic nerve head had mild edema superiorly and minimal atrophy inferiorly. Ocular motility was normal. MRI findings (shown) were normal, ruling out other causes, such as tumor, infarct, and bleeding. Nonarteritic anterior ischemic optic neuropathy (NAION) secondary to severe hypotension in the setting of sepsis and multiple organ failure was diagnosed.

NAION is an idiopathic ischemic insult that involves the short posterior ciliary vessels, which supply the optic nerve head. It is a leading cause of sudden vision loss and the second most common form of optic neuropathy in white men and women older than 50 years. Although NAION affects more than 6000 Americans each year, it is frequently unrecognized.

The most common risk factors are hypertension, diabetes, and nocturnal hypotension. A congenital small cup to disc ratio also predisposes patients to optic nerve ischemia.1 The classic presentation is sudden, painless loss of vision in 1 eye without premonitory symptoms. The vision loss may be central, peripheral, or both. An afferent pupillary defect (Marcus Gunn pupil)—an indication of optic nerve damage—is present when only 1 eye is involved or with asymmetric bilateral disease. Early findings show optic disc edema with hyperemia and often focal hemorrhages. Sectoral edema of the optic nerve is common, particularly of the superior disc margin.

There is no effective acute or preventive therapy for patients with NAION; however, some physicians use corticosteroid therapy. Recurrence in the same eye is unusual; recurrence in the other eye varies between 15% and 40% on average after 2.9 years.2 Control of hypertension, diabetes, and hyperlipidemia may slow progression and/or reduce the incidence of NAION but does not affect the visual losses.

This patient was given pulse therapy with methylprednisone followed by a prednisone taper. His vision only minimally improved.

References

REFERENCES:
1. Desai N, Patel MR, Prisant LM, Thomas DA. Nonarteritic anterior ischemic optic neuropathy. J Clin Hypertens (Greenwich). 2005;7:130-133.
2. Newman NJ, Scherer R, Langenberg P, et al; Ischemic Optic Neuropathy Decompression Trial Research Group. The fellow eye in NAION: report from the ischemic optic neuropathy decompression trial follow-up study. Am J Ophthalmol. 2002;134:317-328.

 
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