Arteritic Anterior Ischemic Optic Neuropathy (AAION)

Arteritic Anterior Ischemic Optic Neuropathy (AAION)
SYMPTOMS Ocular symptoms: Amaurosis fugax (Early sign), Sudden painless vision loss (CF or worse)
Systemic symptoms: Polymyalgia rheumatica (most common systemic symptom), Headaches, Fever, Weight loss, Jaw pain, Scalp tenderness especially in the area of the temporal artery
SIGNS Typically unilateral
Chalky-white optic nerve pallor with associated diffuse edema, Loss of the cup, Blurring of the optic disc margins, Obscurations of the small vasculature at or around the optic nerve, Thickened and edematous retinal nerve fiber layer, Opacification of the retinal nerve fiber layer, Loss of sharp light reflexes around the optic disc, Splinter retinal hemorrhages, Cotton wool spots, Attenuated peripapillary retinal arterioles
Ultimately there will be optic nerve pallor with cupping following resolution of AAION or if AAION is chronic
WORK-UP Cranial nerve testing, Pupils (decrease in direct light response and an APD in the eye with the AAION), EOMs, Color vision (typically abnormal), Visual field (altitudinal or central defect ), Blood pressure evaluation (in order to rule out malignant hypertension), Slit lamp examination, Dilated retinal exam, Fundus photos, OCT, Fluorescein angiography (delayed choroidal filling)
OCT (Optic nerve analysis with EDI and RNFL analysis): *Elevation of the neuroretinal rim thickness *Smooth optic nerve contour *Elevation of the optic disc with involvement of the retinal nerve fiber layer with a smooth, hill-like appearance *Anterior displacement of the Bruch's/RPE complex especially near the Bruch's membrane opening *Presence of peripapillary hyper-reflective ovoid-mass like structures (PHOMS) which represent bulging optic nerve axons *Presence of subretinal fluid (presence of “lazy V sign” especially at the Bruch’s membrane opening) *Thickening of the of the RNFL with typically the nasal side being > 86 microns, temporal side being > 97 microns, superior side being > 149 microns, and inferior side being > 165 microns (Nasal RNFL thickening has the greatest specificity and sensitivity) *Subretinal hyporeflective space between the optic disc and Bruch's membrane opening (SHYPS) is >464 microns
TREATMENT Refer to a neuro-ophthalmologist/ER STAT for additional testing and treatment
Treatment involves high dose intravenous steroids followed by oral steroids
Treatment typically takes 6-12 months or longer
FOLLOW-UP After resolution of AAION, patient should be followed-up every 4-6 months
ADDITIONAL LAB | TESTS Testing will typically be ordered through the neuro-ophthalmologist/ER: ESR with C-reactive protein (ESR will typically be elevated at 70-120 mm/min), CBC with differential, Biopsy of the superficial temporal artery within 1 week after staring systemic steroids
ETIOLOGY Inflammation (composed of giant cells) of the short posterior ciliary arteries that eventually leads to thrombosis and blockage of these arteries. This leads to a decrease in perfusion to the optic nerve with resulting ischemia
DIFFERENTIAL DX Non-Arteritic Anterior Ischemic Optic Neuropathy, Papilledema, Infiltrative optic neuropathy, Diabetic papillopathy, Hypertensive optic neuropathy
NOTES AAIONs are associated with temporal arteritis
The profile of a typical patient with an AAION is a female over the age of 70 years old
The visual prognosis is typically very poor
OCT will go from showing swelling of the RNFL to thinning of the RNFL as optic atrophy develops
Normal ESR for males: age/2 , Normal ESR for females: (age+10)/2
This is considered an ocular emergency as the fellow eye can be involved within 24 hours
Arteritic Anterior Ischemic Optic Neuropathy