NAION: Don’t Forget the Other Eye

Non-arteritic anterior ischemic optic neuropathy (NAION) is the most common acute optic neuropathy in people 50 years of age or older.¹ Individuals with smaller optic discs (< 0.3 mm) are at greater risk of developing NAION due to crowding and obstruction of axoplasmic flow, which may lead to compression of the optic nerve’s vascular supply and, ultimately, acute ischemic attack.

It is important to investigate the possible underlying etiologies associated with NAION. If left untreated, 30% of patients develop NAION in the fellow eye (Figure).² NAION can have a poor prognosis with severe vision loss, especially if it occurs bilaterally, potentially leaving patients with significant visual limitations, such as the inability to drive or perform other everyday tasks.

ABOUT NAION

NAION is a multifactorial condition. Most cases are idiopathic, but various etiologies and medications may be associated with NAION, including: sleep apnea; nocturnal hypotension (in these cases, the patient will likely complain of loss of vision upon waking up from sleep); use of certain medications, such as phosphodiesterase type 5 (PDE5) inhibitors; presence of optic disc drusen; and vasculopathic risk factors (eg, hypertension and diabetes).

Male patients and those with vasculopathic risk factors are most at risk of developing a bilateral, sequential NAION.² It is critical to communicate to patients the importance of following up with their primary care provider to treat the underlying condition or conditions.

If the patient is 55 years of age or older, consider ordering testing for erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and platelets to rule out giant cell arteritis (usually, cases of NAION will demonstrate a normal ESR and CRP). If a patient experiences rapid, sequential vision loss in the fellow eye within 1 to 2 weeks or a recurrence in the same eye, giant cell arteritis should be high on your differential diagnosis. Advise patients with NAION to take an antihypertensive medication in the morning and to avoid taking PDE5 inhibitors. Be sure to communicate the adverse effects of PDE5 inhibitors and the subsequent need to cease this medication with the patient’s prescribing doctor.

DAMAGE CONTROL

There is no treatment shown to improve the prognosis of NAION, but a study by Hayreh et al showed that visual acuity and visual field changes largely stabilized after 6 months.³ Addressing the underlying risk factors is key to preserving vision in the fellow eye.