Ischemic Optic Neuropathy

Ischemic optic neuropathy is sudden vision loss caused by inadequate blood flow to the optic nerve. It is one of the most common causes of acute vision loss in older adults. The condition is divided into two main types: arteritic (caused by giant cell arteritis) and non-arteritic (NAION).

Types of Ischemic Optic Neuropathy

Arteritic Anterior Ischemic Optic Neuropathy (AAION)

Caused by giant cell arteritis (GCA):

• Medical emergency—can cause blindness in both eyes if untreated
• Usually in patients over 70
• Associated symptoms: headache, scalp tenderness, jaw claudication, fatigue
• Vision loss often severe
• Requires immediate high-dose steroids

Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION)

More common form:

• Not caused by inflammation
• Related to vascular risk factors (diabetes, hypertension)
• Vision loss typically less severe than arteritic
• No proven treatment
• "Disc at risk" anatomy often present

Posterior Ischemic Optic Neuropathy

• Affects optic nerve behind the eye
• Less common
• Optic disc appears normal initially
• Various causes including surgery, severe blood loss

Symptoms

NAION Symptoms

• Sudden vision loss upon waking is classic
• Usually noticed first thing in morning
• One eye affected
• Typically painless
• Altitudinal visual field defect—loss of upper or lower half of vision
• Vision loss variable—from mild to severe

Arteritic (GCA) Symptoms

All NAION symptoms plus:

• Headache—especially new or different headache
• Scalp tenderness—hurts to brush hair or lie on pillow
• Jaw claudication—jaw pain/fatigue when chewing
• Fatigue, weight loss, fever
• Polymyalgia rheumatica—shoulder/hip stiffness
• Vision loss often more severe
• May have transient vision loss as warning

When to Seek Emergency Care

Diagnosis

Urgent Blood Tests (Same Day)

• ESR (erythrocyte sedimentation rate)—elevated in GCA
• CRP (C-reactive protein)—elevated in GCA
• CBC—may show anemia or elevated platelets in GCA

Eye Examination Findings

NAION:

• Swollen optic disc with hemorrhages
• Disc often "small and crowded"
• RAPD present

Arteritic:

• Swollen, pale optic disc
• May be more pale than NAION
• Often more severe vision loss

Confirmatory Tests

For suspected GCA:

• Temporal artery biopsy—gold standard
• Should be done within 2 weeks of starting steroids
• Don't delay steroids waiting for biopsy
• May need temporal artery ultrasound

Imaging:

• MRI not usually needed for typical NAION
• May be done to rule out other causes
• OCT shows nerve fiber layer changes

Treatment

For Arteritic (GCA)—EMERGENCY

Immediate treatment:

• High-dose IV methylprednisolone (1 gram/day for 3-5 days)
• Or high-dose oral prednisone (60-100mg) if IV not available
• Start BEFORE biopsy—do not wait

Long-term treatment:

• Prolonged steroid taper (often 1-2 years)
• Tocilizumab (Actemra) may allow steroid reduction
• Bone protection (calcium, vitamin D, bisphosphonate)
• Monitor for steroid side effects

For NAION

No proven treatment, but:

• Control of vascular risk factors essential
• Aspirin (evidence unclear but commonly used)
• Avoid nocturnal hypotension (don't take BP meds at bedtime)
• Sleep apnea evaluation and treatment
• Avoid phosphodiesterase inhibitors (Viagra, etc.) which may increase risk

What doesn't work:

• Steroids (not helpful for NAION)
• Optic nerve decompression surgery (may be harmful)

Risk Factors

NAION Risk Factors

• "Disc at risk" (small, crowded optic disc)
• Diabetes
• Hypertension
• Sleep apnea
• Nocturnal hypotension (blood pressure dropping at night)
• Cardiovascular disease
• Smoking

GCA Risk Factors

• Age over 50 (almost never occurs younger)
• Female sex (2-3x more common)
• Northern European ancestry
• Polymyalgia rheumatica

Prognosis

NAION

• Vision usually stabilizes within weeks
• Some improvement possible but often limited
• 15-20% risk of fellow eye involvement over 5 years
• Focus on preventing second eye involvement

Arteritic

• Without treatment: High risk of second eye blindness (often within days)
• With prompt treatment: Good chance of preserving other eye
• Vision in affected eye rarely recovers
• Requires long-term monitoring and treatment

Frequently Asked Questions

Will my vision recover?

For NAION, some patients have modest improvement, but significant recovery is uncommon. The vision usually stabilizes at the level it reaches in the first few weeks. For arteritic ION, vision in the affected eye rarely improves, but treatment protects the other eye.

Will my other eye be affected?

For NAION, the risk is about 15-20% over 5 years. For untreated GCA, the risk is very high (up to 50% within days). This is why urgent treatment of GCA is essential.

Why did this happen to me?

NAION is related to blood flow to the optic nerve, often influenced by anatomical factors (small optic disc) and vascular risk factors. GCA is an autoimmune inflammatory condition of blood vessels. Neither is caused by anything you did.

Can I prevent this from happening to my other eye?

For NAION: Control vascular risk factors, treat sleep apnea, avoid taking blood pressure medications at bedtime, and don't use phosphodiesterase inhibitors. For GCA: Continue your immunosuppressive treatment as prescribed.

Is ischemic optic neuropathy the same as a stroke?

It's similar in concept—both involve blood flow problems. NAION is sometimes called a "stroke of the optic nerve." However, the treatment and implications are different from brain stroke.

References