Page 115 - The Indian Optician Digital Edition November-December 2021

NON-ARTERITIC

ANTERIOR ISCHEMIC

OPTIC NEUROPATHY

INTRODUCTION

Non-arteritic anterior ischemic optic neuropathy
(NAION) is the most common acute optic neuropathy
in patients over the age of 50 and is the primary
cause of optic nerve-related acute vision loss. In fact,
1
it is the most common optic neuropathy second
only to glaucoma. The exact etiology of NAION is
2
still unknown. However, the pathophysiology of the
condition is believed to involve hypoperfusion and
ischemia of the anterior optic nerve. NAION has a
2
Christian DeJongh strong correlation to a number of systemic risk factors
BA, Fourth-year optometry student at including hypertension, diabetes, hyperlipidemia,
Pacific University College of Optometry cerebral vascular disease, migraine and other
in Forest Grove, Oregon
vasospastic disorders, increased blood viscosity, and
obstructive sleep apnea. All of these systemic risk
3,4
factors are known to affect the blood vessels and
potentially cause hypoperfusion at the optic nerve
head and throughout the body. Diagnosis of NAION
involves ruling out potentially devastating ocular
conditions. Therefore, it is important to understand
the signs and symptoms of NAION in order to make a
proper diagnosis.
CLINICAL PRESENTATION

Patients with NAION typically complain of sudden,
unilateral, and painless vision loss. Pupil testing
4
exhibits an afferent pupillary defect of the affected
Leonid Skorin
2
Jr., OD, DO, MS, FAAO, FAOCO eye. The hallmark finding of NAION is optic disc
edema of the affected eye (Figure 1). The optic disc
margins become indistinct and bulge anteriorly.
Examination of the fellow eye can also aid in the
diagnosis of NAION. A critical finding on examination
is the presence of a physiologically small cup with
a small cup-to-disc ratio (<0.3) in the fellow eye,

111 | CLINICAL