Sudden painless vision loss from optic nerve ischemia
NAION (Non-Arteritic Ischemic Optic Neuropathy) in Los Angeles
Waking up with sudden, painless vision loss in one eye is frightening. NAION — sometimes called an "optic nerve stroke" — is the most common cause of acute optic nerve-related vision loss in older adults. Prompt evaluation by a neuro-ophthalmologist is critical to distinguish NAION from giant cell arteritis, which requires emergency treatment.
What is NAION?
Non-arteritic anterior ischemic optic neuropathy (NAION) occurs when blood flow to the front portion of the optic nerve is disrupted, causing sudden vision loss. Unlike giant cell arteritis (GCA), NAION is not caused by vessel inflammation. It is strongly associated with a small, crowded optic disc anatomy known as a "disc at risk" — an anatomical predisposition present from birth. Systemic risk factors include diabetes, high blood pressure, high cholesterol, sleep apnea, and nocturnal hypotension. The vision loss is typically noticed upon waking in the morning.
Symptoms of NAION
- Sudden, painless vision loss in one eye — often noticed upon waking
- Loss of the upper or lower half of vision (altitudinal visual field defect)
- Blurred or dim vision in the affected eye
- Reduced color perception in the affected eye
- No pain with eye movement (unlike optic neuritis)
- Vision loss that is stable — not progressive over days
Common Causes of NAION
- Small, crowded optic disc ("disc at risk") — the key anatomical predisposition
- Diabetes mellitus
- High blood pressure (hypertension)
- High cholesterol (hyperlipidemia)
- Obstructive sleep apnea
- Nocturnal hypotension (blood pressure drops too low during sleep)
- Certain medications that lower blood pressure excessively at night
- Smoking
How We Evaluate NAION
Evaluation includes a comprehensive neuro-ophthalmic examination with visual acuity, pupil testing, color vision testing, and visual field testing, which typically shows an altitudinal (upper or lower) field defect. Dilated fundus examination reveals a swollen optic disc with small hemorrhages. OCT documents the degree of swelling. Blood work including ESR and CRP is essential to rule out giant cell arteritis. The fellow (unaffected) eye is examined for the "disc at risk" anatomy. Sleep studies may be recommended to evaluate for obstructive sleep apnea.
Treatment Options
Unfortunately, there is no proven treatment that restores vision lost from NAION. Management focuses on identifying and aggressively treating modifiable risk factors — controlling blood pressure, blood sugar, and cholesterol — and screening for and treating sleep apnea. The risk of NAION occurring in the fellow eye is approximately 15-20% over five years, making risk factor management essential.
- Aggressive management of cardiovascular risk factors (blood pressure, diabetes, cholesterol)
- Screening and treatment for obstructive sleep apnea
- Adjusting timing of blood pressure medications if nocturnal hypotension is suspected
- Close monitoring of the fellow eye for early signs
- Serial visual field testing and OCT to track recovery
- Risk factor counseling and lifestyle modification
Why Choose Dr. Ghiam for NAION
- Expert in distinguishing NAION from giant cell arteritis — a critical, time-sensitive distinction
- Thorough evaluation for all modifiable risk factors
- Collaboration with sleep medicine, cardiology, and primary care
- Ongoing monitoring of the fellow eye to detect early changes
- Honest, evidence-based counseling about prognosis and prevention
NAION requires expertise to distinguish it from other causes of sudden vision loss — most importantly from giant cell arteritis, which is a medical emergency. A neuro-ophthalmologist can make this critical distinction rapidly, identify the "disc at risk" anatomy in the fellow eye, and develop a comprehensive plan to reduce the risk of second-eye involvement.
Get Expert Help for NAION
If you have experienced sudden vision loss, especially upon waking, prompt evaluation by a neuro-ophthalmologist is essential. Contact our Los Angeles office today.